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@ -7,6 +7,15 @@
revision = "7da180ee92d8bd8bb8c37fc560e673e6557c392f"
version = "v0.4.7"
[[projects]]
branch = "master"
name = "github.com/alecthomas/template"
packages = [
".",
"parse"
]
revision = "a0175ee3bccc567396460bf5acd36800cb10c49c"
[[projects]]
branch = "master"
name = "github.com/chzyer/readline"
@ -257,6 +266,6 @@
[solve-meta]
analyzer-name = "dep"
analyzer-version = 1
inputs-digest = "4fd2ff9f9869c3f3e30601504f4b00fce69d282ae8df42583a1c60848bfd0766"
inputs-digest = "6e787e78feef91daf35156f0621de05e59affbd8f932a98d929001a86173a909"
solver-name = "gps-cdcl"
solver-version = 1

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Copyright (c) 2012 The Go Authors. All rights reserved.
Redistribution and use in source and binary forms, with or without
modification, are permitted provided that the following conditions are
met:
* Redistributions of source code must retain the above copyright
notice, this list of conditions and the following disclaimer.
* Redistributions in binary form must reproduce the above
copyright notice, this list of conditions and the following disclaimer
in the documentation and/or other materials provided with the
distribution.
* Neither the name of Google Inc. nor the names of its
contributors may be used to endorse or promote products derived from
this software without specific prior written permission.
THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
"AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
(INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

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# Go's `text/template` package with newline elision
This is a fork of Go 1.4's [text/template](http://golang.org/pkg/text/template/) package with one addition: a backslash immediately after a closing delimiter will delete all subsequent newlines until a non-newline.
eg.
```
{{if true}}\
hello
{{end}}\
```
Will result in:
```
hello\n
```
Rather than:
```
\n
hello\n
\n
```

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// Copyright 2011 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
/*
Package template implements data-driven templates for generating textual output.
To generate HTML output, see package html/template, which has the same interface
as this package but automatically secures HTML output against certain attacks.
Templates are executed by applying them to a data structure. Annotations in the
template refer to elements of the data structure (typically a field of a struct
or a key in a map) to control execution and derive values to be displayed.
Execution of the template walks the structure and sets the cursor, represented
by a period '.' and called "dot", to the value at the current location in the
structure as execution proceeds.
The input text for a template is UTF-8-encoded text in any format.
"Actions"--data evaluations or control structures--are delimited by
"{{" and "}}"; all text outside actions is copied to the output unchanged.
Actions may not span newlines, although comments can.
Once parsed, a template may be executed safely in parallel.
Here is a trivial example that prints "17 items are made of wool".
type Inventory struct {
Material string
Count uint
}
sweaters := Inventory{"wool", 17}
tmpl, err := template.New("test").Parse("{{.Count}} items are made of {{.Material}}")
if err != nil { panic(err) }
err = tmpl.Execute(os.Stdout, sweaters)
if err != nil { panic(err) }
More intricate examples appear below.
Actions
Here is the list of actions. "Arguments" and "pipelines" are evaluations of
data, defined in detail below.
*/
// {{/* a comment */}}
// A comment; discarded. May contain newlines.
// Comments do not nest and must start and end at the
// delimiters, as shown here.
/*
{{pipeline}}
The default textual representation of the value of the pipeline
is copied to the output.
{{if pipeline}} T1 {{end}}
If the value of the pipeline is empty, no output is generated;
otherwise, T1 is executed. The empty values are false, 0, any
nil pointer or interface value, and any array, slice, map, or
string of length zero.
Dot is unaffected.
{{if pipeline}} T1 {{else}} T0 {{end}}
If the value of the pipeline is empty, T0 is executed;
otherwise, T1 is executed. Dot is unaffected.
{{if pipeline}} T1 {{else if pipeline}} T0 {{end}}
To simplify the appearance of if-else chains, the else action
of an if may include another if directly; the effect is exactly
the same as writing
{{if pipeline}} T1 {{else}}{{if pipeline}} T0 {{end}}{{end}}
{{range pipeline}} T1 {{end}}
The value of the pipeline must be an array, slice, map, or channel.
If the value of the pipeline has length zero, nothing is output;
otherwise, dot is set to the successive elements of the array,
slice, or map and T1 is executed. If the value is a map and the
keys are of basic type with a defined order ("comparable"), the
elements will be visited in sorted key order.
{{range pipeline}} T1 {{else}} T0 {{end}}
The value of the pipeline must be an array, slice, map, or channel.
If the value of the pipeline has length zero, dot is unaffected and
T0 is executed; otherwise, dot is set to the successive elements
of the array, slice, or map and T1 is executed.
{{template "name"}}
The template with the specified name is executed with nil data.
{{template "name" pipeline}}
The template with the specified name is executed with dot set
to the value of the pipeline.
{{with pipeline}} T1 {{end}}
If the value of the pipeline is empty, no output is generated;
otherwise, dot is set to the value of the pipeline and T1 is
executed.
{{with pipeline}} T1 {{else}} T0 {{end}}
If the value of the pipeline is empty, dot is unaffected and T0
is executed; otherwise, dot is set to the value of the pipeline
and T1 is executed.
Arguments
An argument is a simple value, denoted by one of the following.
- A boolean, string, character, integer, floating-point, imaginary
or complex constant in Go syntax. These behave like Go's untyped
constants, although raw strings may not span newlines.
- The keyword nil, representing an untyped Go nil.
- The character '.' (period):
.
The result is the value of dot.
- A variable name, which is a (possibly empty) alphanumeric string
preceded by a dollar sign, such as
$piOver2
or
$
The result is the value of the variable.
Variables are described below.
- The name of a field of the data, which must be a struct, preceded
by a period, such as
.Field
The result is the value of the field. Field invocations may be
chained:
.Field1.Field2
Fields can also be evaluated on variables, including chaining:
$x.Field1.Field2
- The name of a key of the data, which must be a map, preceded
by a period, such as
.Key
The result is the map element value indexed by the key.
Key invocations may be chained and combined with fields to any
depth:
.Field1.Key1.Field2.Key2
Although the key must be an alphanumeric identifier, unlike with
field names they do not need to start with an upper case letter.
Keys can also be evaluated on variables, including chaining:
$x.key1.key2
- The name of a niladic method of the data, preceded by a period,
such as
.Method
The result is the value of invoking the method with dot as the
receiver, dot.Method(). Such a method must have one return value (of
any type) or two return values, the second of which is an error.
If it has two and the returned error is non-nil, execution terminates
and an error is returned to the caller as the value of Execute.
Method invocations may be chained and combined with fields and keys
to any depth:
.Field1.Key1.Method1.Field2.Key2.Method2
Methods can also be evaluated on variables, including chaining:
$x.Method1.Field
- The name of a niladic function, such as
fun
The result is the value of invoking the function, fun(). The return
types and values behave as in methods. Functions and function
names are described below.
- A parenthesized instance of one the above, for grouping. The result
may be accessed by a field or map key invocation.
print (.F1 arg1) (.F2 arg2)
(.StructValuedMethod "arg").Field
Arguments may evaluate to any type; if they are pointers the implementation
automatically indirects to the base type when required.
If an evaluation yields a function value, such as a function-valued
field of a struct, the function is not invoked automatically, but it
can be used as a truth value for an if action and the like. To invoke
it, use the call function, defined below.
A pipeline is a possibly chained sequence of "commands". A command is a simple
value (argument) or a function or method call, possibly with multiple arguments:
Argument
The result is the value of evaluating the argument.
.Method [Argument...]
The method can be alone or the last element of a chain but,
unlike methods in the middle of a chain, it can take arguments.
The result is the value of calling the method with the
arguments:
dot.Method(Argument1, etc.)
functionName [Argument...]
The result is the value of calling the function associated
with the name:
function(Argument1, etc.)
Functions and function names are described below.
Pipelines
A pipeline may be "chained" by separating a sequence of commands with pipeline
characters '|'. In a chained pipeline, the result of the each command is
passed as the last argument of the following command. The output of the final
command in the pipeline is the value of the pipeline.
The output of a command will be either one value or two values, the second of
which has type error. If that second value is present and evaluates to
non-nil, execution terminates and the error is returned to the caller of
Execute.
Variables
A pipeline inside an action may initialize a variable to capture the result.
The initialization has syntax
$variable := pipeline
where $variable is the name of the variable. An action that declares a
variable produces no output.
If a "range" action initializes a variable, the variable is set to the
successive elements of the iteration. Also, a "range" may declare two
variables, separated by a comma:
range $index, $element := pipeline
in which case $index and $element are set to the successive values of the
array/slice index or map key and element, respectively. Note that if there is
only one variable, it is assigned the element; this is opposite to the
convention in Go range clauses.
A variable's scope extends to the "end" action of the control structure ("if",
"with", or "range") in which it is declared, or to the end of the template if
there is no such control structure. A template invocation does not inherit
variables from the point of its invocation.
When execution begins, $ is set to the data argument passed to Execute, that is,
to the starting value of dot.
Examples
Here are some example one-line templates demonstrating pipelines and variables.
All produce the quoted word "output":
{{"\"output\""}}
A string constant.
{{`"output"`}}
A raw string constant.
{{printf "%q" "output"}}
A function call.
{{"output" | printf "%q"}}
A function call whose final argument comes from the previous
command.
{{printf "%q" (print "out" "put")}}
A parenthesized argument.
{{"put" | printf "%s%s" "out" | printf "%q"}}
A more elaborate call.
{{"output" | printf "%s" | printf "%q"}}
A longer chain.
{{with "output"}}{{printf "%q" .}}{{end}}
A with action using dot.
{{with $x := "output" | printf "%q"}}{{$x}}{{end}}
A with action that creates and uses a variable.
{{with $x := "output"}}{{printf "%q" $x}}{{end}}
A with action that uses the variable in another action.
{{with $x := "output"}}{{$x | printf "%q"}}{{end}}
The same, but pipelined.
Functions
During execution functions are found in two function maps: first in the
template, then in the global function map. By default, no functions are defined
in the template but the Funcs method can be used to add them.
Predefined global functions are named as follows.
and
Returns the boolean AND of its arguments by returning the
first empty argument or the last argument, that is,
"and x y" behaves as "if x then y else x". All the
arguments are evaluated.
call
Returns the result of calling the first argument, which
must be a function, with the remaining arguments as parameters.
Thus "call .X.Y 1 2" is, in Go notation, dot.X.Y(1, 2) where
Y is a func-valued field, map entry, or the like.
The first argument must be the result of an evaluation
that yields a value of function type (as distinct from
a predefined function such as print). The function must
return either one or two result values, the second of which
is of type error. If the arguments don't match the function
or the returned error value is non-nil, execution stops.
html
Returns the escaped HTML equivalent of the textual
representation of its arguments.
index
Returns the result of indexing its first argument by the
following arguments. Thus "index x 1 2 3" is, in Go syntax,
x[1][2][3]. Each indexed item must be a map, slice, or array.
js
Returns the escaped JavaScript equivalent of the textual
representation of its arguments.
len
Returns the integer length of its argument.
not
Returns the boolean negation of its single argument.
or
Returns the boolean OR of its arguments by returning the
first non-empty argument or the last argument, that is,
"or x y" behaves as "if x then x else y". All the
arguments are evaluated.
print
An alias for fmt.Sprint
printf
An alias for fmt.Sprintf
println
An alias for fmt.Sprintln
urlquery
Returns the escaped value of the textual representation of
its arguments in a form suitable for embedding in a URL query.
The boolean functions take any zero value to be false and a non-zero
value to be true.
There is also a set of binary comparison operators defined as
functions:
eq
Returns the boolean truth of arg1 == arg2
ne
Returns the boolean truth of arg1 != arg2
lt
Returns the boolean truth of arg1 < arg2
le
Returns the boolean truth of arg1 <= arg2
gt
Returns the boolean truth of arg1 > arg2
ge
Returns the boolean truth of arg1 >= arg2
For simpler multi-way equality tests, eq (only) accepts two or more
arguments and compares the second and subsequent to the first,
returning in effect
arg1==arg2 || arg1==arg3 || arg1==arg4 ...
(Unlike with || in Go, however, eq is a function call and all the
arguments will be evaluated.)
The comparison functions work on basic types only (or named basic
types, such as "type Celsius float32"). They implement the Go rules
for comparison of values, except that size and exact type are
ignored, so any integer value, signed or unsigned, may be compared
with any other integer value. (The arithmetic value is compared,
not the bit pattern, so all negative integers are less than all
unsigned integers.) However, as usual, one may not compare an int
with a float32 and so on.
Associated templates
Each template is named by a string specified when it is created. Also, each
template is associated with zero or more other templates that it may invoke by
name; such associations are transitive and form a name space of templates.
A template may use a template invocation to instantiate another associated
template; see the explanation of the "template" action above. The name must be
that of a template associated with the template that contains the invocation.
Nested template definitions
When parsing a template, another template may be defined and associated with the
template being parsed. Template definitions must appear at the top level of the
template, much like global variables in a Go program.
The syntax of such definitions is to surround each template declaration with a
"define" and "end" action.
The define action names the template being created by providing a string
constant. Here is a simple example:
`{{define "T1"}}ONE{{end}}
{{define "T2"}}TWO{{end}}
{{define "T3"}}{{template "T1"}} {{template "T2"}}{{end}}
{{template "T3"}}`
This defines two templates, T1 and T2, and a third T3 that invokes the other two
when it is executed. Finally it invokes T3. If executed this template will
produce the text
ONE TWO
By construction, a template may reside in only one association. If it's
necessary to have a template addressable from multiple associations, the
template definition must be parsed multiple times to create distinct *Template
values, or must be copied with the Clone or AddParseTree method.
Parse may be called multiple times to assemble the various associated templates;
see the ParseFiles and ParseGlob functions and methods for simple ways to parse
related templates stored in files.
A template may be executed directly or through ExecuteTemplate, which executes
an associated template identified by name. To invoke our example above, we
might write,
err := tmpl.Execute(os.Stdout, "no data needed")
if err != nil {
log.Fatalf("execution failed: %s", err)
}
or to invoke a particular template explicitly by name,
err := tmpl.ExecuteTemplate(os.Stdout, "T2", "no data needed")
if err != nil {
log.Fatalf("execution failed: %s", err)
}
*/
package template

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// Copyright 2011 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
package template
import (
"bytes"
"fmt"
"io"
"reflect"
"runtime"
"sort"
"strings"
"github.com/alecthomas/template/parse"
)
// state represents the state of an execution. It's not part of the
// template so that multiple executions of the same template
// can execute in parallel.
type state struct {
tmpl *Template
wr io.Writer
node parse.Node // current node, for errors
vars []variable // push-down stack of variable values.
}
// variable holds the dynamic value of a variable such as $, $x etc.
type variable struct {
name string
value reflect.Value
}
// push pushes a new variable on the stack.
func (s *state) push(name string, value reflect.Value) {
s.vars = append(s.vars, variable{name, value})
}
// mark returns the length of the variable stack.
func (s *state) mark() int {
return len(s.vars)
}
// pop pops the variable stack up to the mark.
func (s *state) pop(mark int) {
s.vars = s.vars[0:mark]
}
// setVar overwrites the top-nth variable on the stack. Used by range iterations.
func (s *state) setVar(n int, value reflect.Value) {
s.vars[len(s.vars)-n].value = value
}
// varValue returns the value of the named variable.
func (s *state) varValue(name string) reflect.Value {
for i := s.mark() - 1; i >= 0; i-- {
if s.vars[i].name == name {
return s.vars[i].value
}
}
s.errorf("undefined variable: %s", name)
return zero
}
var zero reflect.Value
// at marks the state to be on node n, for error reporting.
func (s *state) at(node parse.Node) {
s.node = node
}
// doublePercent returns the string with %'s replaced by %%, if necessary,
// so it can be used safely inside a Printf format string.
func doublePercent(str string) string {
if strings.Contains(str, "%") {
str = strings.Replace(str, "%", "%%", -1)
}
return str
}
// errorf formats the error and terminates processing.
func (s *state) errorf(format string, args ...interface{}) {
name := doublePercent(s.tmpl.Name())
if s.node == nil {
format = fmt.Sprintf("template: %s: %s", name, format)
} else {
location, context := s.tmpl.ErrorContext(s.node)
format = fmt.Sprintf("template: %s: executing %q at <%s>: %s", location, name, doublePercent(context), format)
}
panic(fmt.Errorf(format, args...))
}
// errRecover is the handler that turns panics into returns from the top
// level of Parse.
func errRecover(errp *error) {
e := recover()
if e != nil {
switch err := e.(type) {
case runtime.Error:
panic(e)
case error:
*errp = err
default:
panic(e)
}
}
}
// ExecuteTemplate applies the template associated with t that has the given name
// to the specified data object and writes the output to wr.
// If an error occurs executing the template or writing its output,
// execution stops, but partial results may already have been written to
// the output writer.
// A template may be executed safely in parallel.
func (t *Template) ExecuteTemplate(wr io.Writer, name string, data interface{}) error {
tmpl := t.tmpl[name]
if tmpl == nil {
return fmt.Errorf("template: no template %q associated with template %q", name, t.name)
}
return tmpl.Execute(wr, data)
}
// Execute applies a parsed template to the specified data object,
// and writes the output to wr.
// If an error occurs executing the template or writing its output,
// execution stops, but partial results may already have been written to
// the output writer.
// A template may be executed safely in parallel.
func (t *Template) Execute(wr io.Writer, data interface{}) (err error) {
defer errRecover(&err)
value := reflect.ValueOf(data)
state := &state{
tmpl: t,
wr: wr,
vars: []variable{{"$", value}},
}
t.init()
if t.Tree == nil || t.Root == nil {
var b bytes.Buffer
for name, tmpl := range t.tmpl {
if tmpl.Tree == nil || tmpl.Root == nil {
continue
}
if b.Len() > 0 {
b.WriteString(", ")
}
fmt.Fprintf(&b, "%q", name)
}
var s string
if b.Len() > 0 {
s = "; defined templates are: " + b.String()
}
state.errorf("%q is an incomplete or empty template%s", t.Name(), s)
}
state.walk(value, t.Root)
return
}
// Walk functions step through the major pieces of the template structure,
// generating output as they go.
func (s *state) walk(dot reflect.Value, node parse.Node) {
s.at(node)
switch node := node.(type) {
case *parse.ActionNode:
// Do not pop variables so they persist until next end.
// Also, if the action declares variables, don't print the result.
val := s.evalPipeline(dot, node.Pipe)
if len(node.Pipe.Decl) == 0 {
s.printValue(node, val)
}
case *parse.IfNode:
s.walkIfOrWith(parse.NodeIf, dot, node.Pipe, node.List, node.ElseList)
case *parse.ListNode:
for _, node := range node.Nodes {
s.walk(dot, node)
}
case *parse.RangeNode:
s.walkRange(dot, node)
case *parse.TemplateNode:
s.walkTemplate(dot, node)
case *parse.TextNode:
if _, err := s.wr.Write(node.Text); err != nil {
s.errorf("%s", err)
}
case *parse.WithNode:
s.walkIfOrWith(parse.NodeWith, dot, node.Pipe, node.List, node.ElseList)
default:
s.errorf("unknown node: %s", node)
}
}
// walkIfOrWith walks an 'if' or 'with' node. The two control structures
// are identical in behavior except that 'with' sets dot.
func (s *state) walkIfOrWith(typ parse.NodeType, dot reflect.Value, pipe *parse.PipeNode, list, elseList *parse.ListNode) {
defer s.pop(s.mark())
val := s.evalPipeline(dot, pipe)
truth, ok := isTrue(val)
if !ok {
s.errorf("if/with can't use %v", val)
}
if truth {
if typ == parse.NodeWith {
s.walk(val, list)
} else {
s.walk(dot, list)
}
} else if elseList != nil {
s.walk(dot, elseList)
}
}
// isTrue reports whether the value is 'true', in the sense of not the zero of its type,
// and whether the value has a meaningful truth value.
func isTrue(val reflect.Value) (truth, ok bool) {
if !val.IsValid() {
// Something like var x interface{}, never set. It's a form of nil.
return false, true
}
switch val.Kind() {
case reflect.Array, reflect.Map, reflect.Slice, reflect.String:
truth = val.Len() > 0
case reflect.Bool:
truth = val.Bool()
case reflect.Complex64, reflect.Complex128:
truth = val.Complex() != 0
case reflect.Chan, reflect.Func, reflect.Ptr, reflect.Interface:
truth = !val.IsNil()
case reflect.Int, reflect.Int8, reflect.Int16, reflect.Int32, reflect.Int64:
truth = val.Int() != 0
case reflect.Float32, reflect.Float64:
truth = val.Float() != 0
case reflect.Uint, reflect.Uint8, reflect.Uint16, reflect.Uint32, reflect.Uint64, reflect.Uintptr:
truth = val.Uint() != 0
case reflect.Struct:
truth = true // Struct values are always true.
default:
return
}
return truth, true
}
func (s *state) walkRange(dot reflect.Value, r *parse.RangeNode) {
s.at(r)
defer s.pop(s.mark())
val, _ := indirect(s.evalPipeline(dot, r.Pipe))
// mark top of stack before any variables in the body are pushed.
mark := s.mark()
oneIteration := func(index, elem reflect.Value) {
// Set top var (lexically the second if there are two) to the element.
if len(r.Pipe.Decl) > 0 {
s.setVar(1, elem)
}
// Set next var (lexically the first if there are two) to the index.
if len(r.Pipe.Decl) > 1 {
s.setVar(2, index)
}
s.walk(elem, r.List)
s.pop(mark)
}
switch val.Kind() {
case reflect.Array, reflect.Slice:
if val.Len() == 0 {
break
}
for i := 0; i < val.Len(); i++ {
oneIteration(reflect.ValueOf(i), val.Index(i))
}
return
case reflect.Map:
if val.Len() == 0 {
break
}
for _, key := range sortKeys(val.MapKeys()) {
oneIteration(key, val.MapIndex(key))
}
return
case reflect.Chan:
if val.IsNil() {
break
}
i := 0
for ; ; i++ {
elem, ok := val.Recv()
if !ok {
break
}
oneIteration(reflect.ValueOf(i), elem)
}
if i == 0 {
break
}
return
case reflect.Invalid:
break // An invalid value is likely a nil map, etc. and acts like an empty map.
default:
s.errorf("range can't iterate over %v", val)
}
if r.ElseList != nil {
s.walk(dot, r.ElseList)
}
}
func (s *state) walkTemplate(dot reflect.Value, t *parse.TemplateNode) {
s.at(t)
tmpl := s.tmpl.tmpl[t.Name]
if tmpl == nil {
s.errorf("template %q not defined", t.Name)
}
// Variables declared by the pipeline persist.
dot = s.evalPipeline(dot, t.Pipe)
newState := *s
newState.tmpl = tmpl
// No dynamic scoping: template invocations inherit no variables.
newState.vars = []variable{{"$", dot}}
newState.walk(dot, tmpl.Root)
}
// Eval functions evaluate pipelines, commands, and their elements and extract
// values from the data structure by examining fields, calling methods, and so on.
// The printing of those values happens only through walk functions.
// evalPipeline returns the value acquired by evaluating a pipeline. If the
// pipeline has a variable declaration, the variable will be pushed on the
// stack. Callers should therefore pop the stack after they are finished
// executing commands depending on the pipeline value.
func (s *state) evalPipeline(dot reflect.Value, pipe *parse.PipeNode) (value reflect.Value) {
if pipe == nil {
return
}
s.at(pipe)
for _, cmd := range pipe.Cmds {
value = s.evalCommand(dot, cmd, value) // previous value is this one's final arg.
// If the object has type interface{}, dig down one level to the thing inside.
if value.Kind() == reflect.Interface && value.Type().NumMethod() == 0 {
value = reflect.ValueOf(value.Interface()) // lovely!
}
}
for _, variable := range pipe.Decl {
s.push(variable.Ident[0], value)
}
return value
}
func (s *state) notAFunction(args []parse.Node, final reflect.Value) {
if len(args) > 1 || final.IsValid() {
s.errorf("can't give argument to non-function %s", args[0])
}
}
func (s *state) evalCommand(dot reflect.Value, cmd *parse.CommandNode, final reflect.Value) reflect.Value {
firstWord := cmd.Args[0]
switch n := firstWord.(type) {
case *parse.FieldNode:
return s.evalFieldNode(dot, n, cmd.Args, final)
case *parse.ChainNode:
return s.evalChainNode(dot, n, cmd.Args, final)
case *parse.IdentifierNode:
// Must be a function.
return s.evalFunction(dot, n, cmd, cmd.Args, final)
case *parse.PipeNode:
// Parenthesized pipeline. The arguments are all inside the pipeline; final is ignored.
return s.evalPipeline(dot, n)
case *parse.VariableNode:
return s.evalVariableNode(dot, n, cmd.Args, final)
}
s.at(firstWord)
s.notAFunction(cmd.Args, final)
switch word := firstWord.(type) {
case *parse.BoolNode:
return reflect.ValueOf(word.True)
case *parse.DotNode:
return dot
case *parse.NilNode:
s.errorf("nil is not a command")
case *parse.NumberNode:
return s.idealConstant(word)
case *parse.StringNode:
return reflect.ValueOf(word.Text)
}
s.errorf("can't evaluate command %q", firstWord)
panic("not reached")
}
// idealConstant is called to return the value of a number in a context where
// we don't know the type. In that case, the syntax of the number tells us
// its type, and we use Go rules to resolve. Note there is no such thing as
// a uint ideal constant in this situation - the value must be of int type.
func (s *state) idealConstant(constant *parse.NumberNode) reflect.Value {
// These are ideal constants but we don't know the type
// and we have no context. (If it was a method argument,
// we'd know what we need.) The syntax guides us to some extent.
s.at(constant)
switch {
case constant.IsComplex:
return reflect.ValueOf(constant.Complex128) // incontrovertible.
case constant.IsFloat && !isHexConstant(constant.Text) && strings.IndexAny(constant.Text, ".eE") >= 0:
return reflect.ValueOf(constant.Float64)
case constant.IsInt:
n := int(constant.Int64)
if int64(n) != constant.Int64 {
s.errorf("%s overflows int", constant.Text)
}
return reflect.ValueOf(n)
case constant.IsUint:
s.errorf("%s overflows int", constant.Text)
}
return zero
}
func isHexConstant(s string) bool {
return len(s) > 2 && s[0] == '0' && (s[1] == 'x' || s[1] == 'X')
}
func (s *state) evalFieldNode(dot reflect.Value, field *parse.FieldNode, args []parse.Node, final reflect.Value) reflect.Value {
s.at(field)
return s.evalFieldChain(dot, dot, field, field.Ident, args, final)
}
func (s *state) evalChainNode(dot reflect.Value, chain *parse.ChainNode, args []parse.Node, final reflect.Value) reflect.Value {
s.at(chain)
// (pipe).Field1.Field2 has pipe as .Node, fields as .Field. Eval the pipeline, then the fields.
pipe := s.evalArg(dot, nil, chain.Node)
if len(chain.Field) == 0 {
s.errorf("internal error: no fields in evalChainNode")
}
return s.evalFieldChain(dot, pipe, chain, chain.Field, args, final)
}
func (s *state) evalVariableNode(dot reflect.Value, variable *parse.VariableNode, args []parse.Node, final reflect.Value) reflect.Value {
// $x.Field has $x as the first ident, Field as the second. Eval the var, then the fields.
s.at(variable)
value := s.varValue(variable.Ident[0])
if len(variable.Ident) == 1 {
s.notAFunction(args, final)
return value
}
return s.evalFieldChain(dot, value, variable, variable.Ident[1:], args, final)
}
// evalFieldChain evaluates .X.Y.Z possibly followed by arguments.
// dot is the environment in which to evaluate arguments, while
// receiver is the value being walked along the chain.
func (s *state) evalFieldChain(dot, receiver reflect.Value, node parse.Node, ident []string, args []parse.Node, final reflect.Value) reflect.Value {
n := len(ident)
for i := 0; i < n-1; i++ {
receiver = s.evalField(dot, ident[i], node, nil, zero, receiver)
}
// Now if it's a method, it gets the arguments.
return s.evalField(dot, ident[n-1], node, args, final, receiver)
}
func (s *state) evalFunction(dot reflect.Value, node *parse.IdentifierNode, cmd parse.Node, args []parse.Node, final reflect.Value) reflect.Value {
s.at(node)
name := node.Ident
function, ok := findFunction(name, s.tmpl)
if !ok {
s.errorf("%q is not a defined function", name)
}
return s.evalCall(dot, function, cmd, name, args, final)
}
// evalField evaluates an expression like (.Field) or (.Field arg1 arg2).
// The 'final' argument represents the return value from the preceding
// value of the pipeline, if any.
func (s *state) evalField(dot reflect.Value, fieldName string, node parse.Node, args []parse.Node, final, receiver reflect.Value) reflect.Value {
if !receiver.IsValid() {
return zero
}
typ := receiver.Type()
receiver, _ = indirect(receiver)
// Unless it's an interface, need to get to a value of type *T to guarantee
// we see all methods of T and *T.
ptr := receiver
if ptr.Kind() != reflect.Interface && ptr.CanAddr() {
ptr = ptr.Addr()
}
if method := ptr.MethodByName(fieldName); method.IsValid() {
return s.evalCall(dot, method, node, fieldName, args, final)
}
hasArgs := len(args) > 1 || final.IsValid()
// It's not a method; must be a field of a struct or an element of a map. The receiver must not be nil.
receiver, isNil := indirect(receiver)
if isNil {
s.errorf("nil pointer evaluating %s.%s", typ, fieldName)
}
switch receiver.Kind() {
case reflect.Struct:
tField, ok := receiver.Type().FieldByName(fieldName)
if ok {
field := receiver.FieldByIndex(tField.Index)
if tField.PkgPath != "" { // field is unexported
s.errorf("%s is an unexported field of struct type %s", fieldName, typ)
}
// If it's a function, we must call it.
if hasArgs {
s.errorf("%s has arguments but cannot be invoked as function", fieldName)
}
return field
}
s.errorf("%s is not a field of struct type %s", fieldName, typ)
case reflect.Map:
// If it's a map, attempt to use the field name as a key.
nameVal := reflect.ValueOf(fieldName)
if nameVal.Type().AssignableTo(receiver.Type().Key()) {
if hasArgs {
s.errorf("%s is not a method but has arguments", fieldName)
}
return receiver.MapIndex(nameVal)
}
}
s.errorf("can't evaluate field %s in type %s", fieldName, typ)
panic("not reached")
}
var (
errorType = reflect.TypeOf((*error)(nil)).Elem()
fmtStringerType = reflect.TypeOf((*fmt.Stringer)(nil)).Elem()
)
// evalCall executes a function or method call. If it's a method, fun already has the receiver bound, so
// it looks just like a function call. The arg list, if non-nil, includes (in the manner of the shell), arg[0]
// as the function itself.
func (s *state) evalCall(dot, fun reflect.Value, node parse.Node, name string, args []parse.Node, final reflect.Value) reflect.Value {
if args != nil {
args = args[1:] // Zeroth arg is function name/node; not passed to function.
}
typ := fun.Type()
numIn := len(args)
if final.IsValid() {
numIn++
}
numFixed := len(args)
if typ.IsVariadic() {
numFixed = typ.NumIn() - 1 // last arg is the variadic one.
if numIn < numFixed {
s.errorf("wrong number of args for %s: want at least %d got %d", name, typ.NumIn()-1, len(args))
}
} else if numIn < typ.NumIn()-1 || !typ.IsVariadic() && numIn != typ.NumIn() {
s.errorf("wrong number of args for %s: want %d got %d", name, typ.NumIn(), len(args))
}
if !goodFunc(typ) {
// TODO: This could still be a confusing error; maybe goodFunc should provide info.
s.errorf("can't call method/function %q with %d results", name, typ.NumOut())
}
// Build the arg list.
argv := make([]reflect.Value, numIn)
// Args must be evaluated. Fixed args first.
i := 0
for ; i < numFixed && i < len(args); i++ {
argv[i] = s.evalArg(dot, typ.In(i), args[i])
}
// Now the ... args.
if typ.IsVariadic() {
argType := typ.In(typ.NumIn() - 1).Elem() // Argument is a slice.
for ; i < len(args); i++ {
argv[i] = s.evalArg(dot, argType, args[i])
}
}
// Add final value if necessary.
if final.IsValid() {
t := typ.In(typ.NumIn() - 1)
if typ.IsVariadic() {
t = t.Elem()
}
argv[i] = s.validateType(final, t)
}
result := fun.Call(argv)
// If we have an error that is not nil, stop execution and return that error to the caller.
if len(result) == 2 && !result[1].IsNil() {
s.at(node)
s.errorf("error calling %s: %s", name, result[1].Interface().(error))
}
return result[0]
}
// canBeNil reports whether an untyped nil can be assigned to the type. See reflect.Zero.
func canBeNil(typ reflect.Type) bool {
switch typ.Kind() {
case reflect.Chan, reflect.Func, reflect.Interface, reflect.Map, reflect.Ptr, reflect.Slice:
return true
}
return false
}
// validateType guarantees that the value is valid and assignable to the type.
func (s *state) validateType(value reflect.Value, typ reflect.Type) reflect.Value {
if !value.IsValid() {
if typ == nil || canBeNil(typ) {
// An untyped nil interface{}. Accept as a proper nil value.
return reflect.Zero(typ)
}
s.errorf("invalid value; expected %s", typ)
}
if typ != nil && !value.Type().AssignableTo(typ) {
if value.Kind() == reflect.Interface && !value.IsNil() {
value = value.Elem()
if value.Type().AssignableTo(typ) {
return value
}
// fallthrough
}
// Does one dereference or indirection work? We could do more, as we
// do with method receivers, but that gets messy and method receivers
// are much more constrained, so it makes more sense there than here.
// Besides, one is almost always all you need.
switch {
case value.Kind() == reflect.Ptr && value.Type().Elem().AssignableTo(typ):
value = value.Elem()
if !value.IsValid() {
s.errorf("dereference of nil pointer of type %s", typ)
}
case reflect.PtrTo(value.Type()).AssignableTo(typ) && value.CanAddr():
value = value.Addr()
default:
s.errorf("wrong type for value; expected %s; got %s", typ, value.Type())
}
}
return value
}
func (s *state) evalArg(dot reflect.Value, typ reflect.Type, n parse.Node) reflect.Value {
s.at(n)
switch arg := n.(type) {
case *parse.DotNode:
return s.validateType(dot, typ)
case *parse.NilNode:
if canBeNil(typ) {
return reflect.Zero(typ)
}
s.errorf("cannot assign nil to %s", typ)
case *parse.FieldNode:
return s.validateType(s.evalFieldNode(dot, arg, []parse.Node{n}, zero), typ)
case *parse.VariableNode:
return s.validateType(s.evalVariableNode(dot, arg, nil, zero), typ)
case *parse.PipeNode:
return s.validateType(s.evalPipeline(dot, arg), typ)
case *parse.IdentifierNode:
return s.evalFunction(dot, arg, arg, nil, zero)
case *parse.ChainNode:
return s.validateType(s.evalChainNode(dot, arg, nil, zero), typ)
}
switch typ.Kind() {
case reflect.Bool:
return s.evalBool(typ, n)
case reflect.Complex64, reflect.Complex128:
return s.evalComplex(typ, n)
case reflect.Float32, reflect.Float64:
return s.evalFloat(typ, n)
case reflect.Int, reflect.Int8, reflect.Int16, reflect.Int32, reflect.Int64:
return s.evalInteger(typ, n)
case reflect.Interface:
if typ.NumMethod() == 0 {
return s.evalEmptyInterface(dot, n)
}
case reflect.String:
return s.evalString(typ, n)
case reflect.Uint, reflect.Uint8, reflect.Uint16, reflect.Uint32, reflect.Uint64, reflect.Uintptr:
return s.evalUnsignedInteger(typ, n)
}
s.errorf("can't handle %s for arg of type %s", n, typ)
panic("not reached")
}
func (s *state) evalBool(typ reflect.Type, n parse.Node) reflect.Value {
s.at(n)
if n, ok := n.(*parse.BoolNode); ok {
value := reflect.New(typ).Elem()
value.SetBool(n.True)
return value
}
s.errorf("expected bool; found %s", n)
panic("not reached")
}
func (s *state) evalString(typ reflect.Type, n parse.Node) reflect.Value {
s.at(n)
if n, ok := n.(*parse.StringNode); ok {
value := reflect.New(typ).Elem()
value.SetString(n.Text)
return value
}
s.errorf("expected string; found %s", n)
panic("not reached")
}
func (s *state) evalInteger(typ reflect.Type, n parse.Node) reflect.Value {
s.at(n)
if n, ok := n.(*parse.NumberNode); ok && n.IsInt {
value := reflect.New(typ).Elem()
value.SetInt(n.Int64)
return value
}
s.errorf("expected integer; found %s", n)
panic("not reached")
}
func (s *state) evalUnsignedInteger(typ reflect.Type, n parse.Node) reflect.Value {
s.at(n)
if n, ok := n.(*parse.NumberNode); ok && n.IsUint {
value := reflect.New(typ).Elem()
value.SetUint(n.Uint64)
return value
}
s.errorf("expected unsigned integer; found %s", n)
panic("not reached")
}
func (s *state) evalFloat(typ reflect.Type, n parse.Node) reflect.Value {
s.at(n)
if n, ok := n.(*parse.NumberNode); ok && n.IsFloat {
value := reflect.New(typ).Elem()
value.SetFloat(n.Float64)
return value
}
s.errorf("expected float; found %s", n)
panic("not reached")
}
func (s *state) evalComplex(typ reflect.Type, n parse.Node) reflect.Value {
if n, ok := n.(*parse.NumberNode); ok && n.IsComplex {
value := reflect.New(typ).Elem()
value.SetComplex(n.Complex128)
return value
}
s.errorf("expected complex; found %s", n)
panic("not reached")
}
func (s *state) evalEmptyInterface(dot reflect.Value, n parse.Node) reflect.Value {
s.at(n)
switch n := n.(type) {
case *parse.BoolNode:
return reflect.ValueOf(n.True)
case *parse.DotNode:
return dot
case *parse.FieldNode:
return s.evalFieldNode(dot, n, nil, zero)
case *parse.IdentifierNode:
return s.evalFunction(dot, n, n, nil, zero)
case *parse.NilNode:
// NilNode is handled in evalArg, the only place that calls here.
s.errorf("evalEmptyInterface: nil (can't happen)")
case *parse.NumberNode:
return s.idealConstant(n)
case *parse.StringNode:
return reflect.ValueOf(n.Text)
case *parse.VariableNode:
return s.evalVariableNode(dot, n, nil, zero)
case *parse.PipeNode:
return s.evalPipeline(dot, n)
}
s.errorf("can't handle assignment of %s to empty interface argument", n)
panic("not reached")
}
// indirect returns the item at the end of indirection, and a bool to indicate if it's nil.
// We indirect through pointers and empty interfaces (only) because
// non-empty interfaces have methods we might need.
func indirect(v reflect.Value) (rv reflect.Value, isNil bool) {
for ; v.Kind() == reflect.Ptr || v.Kind() == reflect.Interface; v = v.Elem() {
if v.IsNil() {
return v, true
}
if v.Kind() == reflect.Interface && v.NumMethod() > 0 {
break
}
}
return v, false
}
// printValue writes the textual representation of the value to the output of
// the template.
func (s *state) printValue(n parse.Node, v reflect.Value) {
s.at(n)
iface, ok := printableValue(v)
if !ok {
s.errorf("can't print %s of type %s", n, v.Type())
}
fmt.Fprint(s.wr, iface)
}
// printableValue returns the, possibly indirected, interface value inside v that
// is best for a call to formatted printer.
func printableValue(v reflect.Value) (interface{}, bool) {
if v.Kind() == reflect.Ptr {
v, _ = indirect(v) // fmt.Fprint handles nil.
}
if !v.IsValid() {
return "<no value>", true
}
if !v.Type().Implements(errorType) && !v.Type().Implements(fmtStringerType) {
if v.CanAddr() && (reflect.PtrTo(v.Type()).Implements(errorType) || reflect.PtrTo(v.Type()).Implements(fmtStringerType)) {
v = v.Addr()
} else {
switch v.Kind() {
case reflect.Chan, reflect.Func:
return nil, false
}
}
}
return v.Interface(), true
}
// Types to help sort the keys in a map for reproducible output.
type rvs []reflect.Value
func (x rvs) Len() int { return len(x) }
func (x rvs) Swap(i, j int) { x[i], x[j] = x[j], x[i] }
type rvInts struct{ rvs }
func (x rvInts) Less(i, j int) bool { return x.rvs[i].Int() < x.rvs[j].Int() }
type rvUints struct{ rvs }
func (x rvUints) Less(i, j int) bool { return x.rvs[i].Uint() < x.rvs[j].Uint() }
type rvFloats struct{ rvs }
func (x rvFloats) Less(i, j int) bool { return x.rvs[i].Float() < x.rvs[j].Float() }
type rvStrings struct{ rvs }
func (x rvStrings) Less(i, j int) bool { return x.rvs[i].String() < x.rvs[j].String() }
// sortKeys sorts (if it can) the slice of reflect.Values, which is a slice of map keys.
func sortKeys(v []reflect.Value) []reflect.Value {
if len(v) <= 1 {
return v
}
switch v[0].Kind() {
case reflect.Float32, reflect.Float64:
sort.Sort(rvFloats{v})
case reflect.Int, reflect.Int8, reflect.Int16, reflect.Int32, reflect.Int64:
sort.Sort(rvInts{v})
case reflect.String:
sort.Sort(rvStrings{v})
case reflect.Uint, reflect.Uint8, reflect.Uint16, reflect.Uint32, reflect.Uint64, reflect.Uintptr:
sort.Sort(rvUints{v})
}
return v
}

598
vendor/github.com/alecthomas/template/funcs.go generated vendored Normal file
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@ -0,0 +1,598 @@
// Copyright 2011 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
package template
import (
"bytes"
"errors"
"fmt"
"io"
"net/url"
"reflect"
"strings"
"unicode"
"unicode/utf8"
)
// FuncMap is the type of the map defining the mapping from names to functions.
// Each function must have either a single return value, or two return values of
// which the second has type error. In that case, if the second (error)
// return value evaluates to non-nil during execution, execution terminates and
// Execute returns that error.
type FuncMap map[string]interface{}
var builtins = FuncMap{
"and": and,
"call": call,
"html": HTMLEscaper,
"index": index,
"js": JSEscaper,
"len": length,
"not": not,
"or": or,
"print": fmt.Sprint,
"printf": fmt.Sprintf,
"println": fmt.Sprintln,
"urlquery": URLQueryEscaper,
// Comparisons
"eq": eq, // ==
"ge": ge, // >=
"gt": gt, // >
"le": le, // <=
"lt": lt, // <
"ne": ne, // !=
}
var builtinFuncs = createValueFuncs(builtins)
// createValueFuncs turns a FuncMap into a map[string]reflect.Value
func createValueFuncs(funcMap FuncMap) map[string]reflect.Value {
m := make(map[string]reflect.Value)
addValueFuncs(m, funcMap)
return m
}
// addValueFuncs adds to values the functions in funcs, converting them to reflect.Values.
func addValueFuncs(out map[string]reflect.Value, in FuncMap) {
for name, fn := range in {
v := reflect.ValueOf(fn)
if v.Kind() != reflect.Func {
panic("value for " + name + " not a function")
}
if !goodFunc(v.Type()) {
panic(fmt.Errorf("can't install method/function %q with %d results", name, v.Type().NumOut()))
}
out[name] = v
}
}
// addFuncs adds to values the functions in funcs. It does no checking of the input -
// call addValueFuncs first.
func addFuncs(out, in FuncMap) {
for name, fn := range in {
out[name] = fn
}
}
// goodFunc checks that the function or method has the right result signature.
func goodFunc(typ reflect.Type) bool {
// We allow functions with 1 result or 2 results where the second is an error.
switch {
case typ.NumOut() == 1:
return true
case typ.NumOut() == 2 && typ.Out(1) == errorType:
return true
}
return false
}
// findFunction looks for a function in the template, and global map.
func findFunction(name string, tmpl *Template) (reflect.Value, bool) {
if tmpl != nil && tmpl.common != nil {
if fn := tmpl.execFuncs[name]; fn.IsValid() {
return fn, true
}
}
if fn := builtinFuncs[name]; fn.IsValid() {
return fn, true
}
return reflect.Value{}, false
}
// Indexing.
// index returns the result of indexing its first argument by the following
// arguments. Thus "index x 1 2 3" is, in Go syntax, x[1][2][3]. Each
// indexed item must be a map, slice, or array.
func index(item interface{}, indices ...interface{}) (interface{}, error) {
v := reflect.ValueOf(item)
for _, i := range indices {
index := reflect.ValueOf(i)
var isNil bool
if v, isNil = indirect(v); isNil {
return nil, fmt.Errorf("index of nil pointer")
}
switch v.Kind() {
case reflect.Array, reflect.Slice, reflect.String:
var x int64
switch index.Kind() {
case reflect.Int, reflect.Int8, reflect.Int16, reflect.Int32, reflect.Int64:
x = index.Int()
case reflect.Uint, reflect.Uint8, reflect.Uint16, reflect.Uint32, reflect.Uint64, reflect.Uintptr:
x = int64(index.Uint())
default:
return nil, fmt.Errorf("cannot index slice/array with type %s", index.Type())
}
if x < 0 || x >= int64(v.Len()) {
return nil, fmt.Errorf("index out of range: %d", x)
}
v = v.Index(int(x))
case reflect.Map:
if !index.IsValid() {
index = reflect.Zero(v.Type().Key())
}
if !index.Type().AssignableTo(v.Type().Key()) {
return nil, fmt.Errorf("%s is not index type for %s", index.Type(), v.Type())
}
if x := v.MapIndex(index); x.IsValid() {
v = x
} else {
v = reflect.Zero(v.Type().Elem())
}
default:
return nil, fmt.Errorf("can't index item of type %s", v.Type())
}
}
return v.Interface(), nil
}
// Length
// length returns the length of the item, with an error if it has no defined length.
func length(item interface{}) (int, error) {
v, isNil := indirect(reflect.ValueOf(item))
if isNil {
return 0, fmt.Errorf("len of nil pointer")
}
switch v.Kind() {
case reflect.Array, reflect.Chan, reflect.Map, reflect.Slice, reflect.String:
return v.Len(), nil
}
return 0, fmt.Errorf("len of type %s", v.Type())
}
// Function invocation
// call returns the result of evaluating the first argument as a function.
// The function must return 1 result, or 2 results, the second of which is an error.
func call(fn interface{}, args ...interface{}) (interface{}, error) {
v := reflect.ValueOf(fn)
typ := v.Type()
if typ.Kind() != reflect.Func {
return nil, fmt.Errorf("non-function of type %s", typ)
}
if !goodFunc(typ) {
return nil, fmt.Errorf("function called with %d args; should be 1 or 2", typ.NumOut())
}
numIn := typ.NumIn()
var dddType reflect.Type
if typ.IsVariadic() {
if len(args) < numIn-1 {
return nil, fmt.Errorf("wrong number of args: got %d want at least %d", len(args), numIn-1)
}
dddType = typ.In(numIn - 1).Elem()
} else {
if len(args) != numIn {
return nil, fmt.Errorf("wrong number of args: got %d want %d", len(args), numIn)
}
}
argv := make([]reflect.Value, len(args))
for i, arg := range args {
value := reflect.ValueOf(arg)
// Compute the expected type. Clumsy because of variadics.
var argType reflect.Type
if !typ.IsVariadic() || i < numIn-1 {
argType = typ.In(i)
} else {
argType = dddType
}
if !value.IsValid() && canBeNil(argType) {
value = reflect.Zero(argType)
}
if !value.Type().AssignableTo(argType) {
return nil, fmt.Errorf("arg %d has type %s; should be %s", i, value.Type(), argType)
}
argv[i] = value
}
result := v.Call(argv)
if len(result) == 2 && !result[1].IsNil() {
return result[0].Interface(), result[1].Interface().(error)
}
return result[0].Interface(), nil
}
// Boolean logic.
func truth(a interface{}) bool {
t, _ := isTrue(reflect.ValueOf(a))
return t
}
// and computes the Boolean AND of its arguments, returning
// the first false argument it encounters, or the last argument.
func and(arg0 interface{}, args ...interface{}) interface{} {
if !truth(arg0) {
return arg0
}
for i := range args {
arg0 = args[i]
if !truth(arg0) {
break
}
}
return arg0
}
// or computes the Boolean OR of its arguments, returning
// the first true argument it encounters, or the last argument.
func or(arg0 interface{}, args ...interface{}) interface{} {
if truth(arg0) {
return arg0
}
for i := range args {
arg0 = args[i]
if truth(arg0) {
break
}
}
return arg0
}
// not returns the Boolean negation of its argument.
func not(arg interface{}) (truth bool) {
truth, _ = isTrue(reflect.ValueOf(arg))
return !truth
}
// Comparison.
// TODO: Perhaps allow comparison between signed and unsigned integers.
var (
errBadComparisonType = errors.New("invalid type for comparison")
errBadComparison = errors.New("incompatible types for comparison")
errNoComparison = errors.New("missing argument for comparison")
)
type kind int
const (
invalidKind kind = iota
boolKind
complexKind
intKind
floatKind
integerKind
stringKind
uintKind
)
func basicKind(v reflect.Value) (kind, error) {
switch v.Kind() {
case reflect.Bool:
return boolKind, nil
case reflect.Int, reflect.Int8, reflect.Int16, reflect.Int32, reflect.Int64:
return intKind, nil
case reflect.Uint, reflect.Uint8, reflect.Uint16, reflect.Uint32, reflect.Uint64, reflect.Uintptr:
return uintKind, nil
case reflect.Float32, reflect.Float64:
return floatKind, nil
case reflect.Complex64, reflect.Complex128:
return complexKind, nil
case reflect.String:
return stringKind, nil
}
return invalidKind, errBadComparisonType
}
// eq evaluates the comparison a == b || a == c || ...
func eq(arg1 interface{}, arg2 ...interface{}) (bool, error) {
v1 := reflect.ValueOf(arg1)
k1, err := basicKind(v1)
if err != nil {
return false, err
}
if len(arg2) == 0 {
return false, errNoComparison
}
for _, arg := range arg2 {
v2 := reflect.ValueOf(arg)
k2, err := basicKind(v2)
if err != nil {
return false, err
}
truth := false
if k1 != k2 {
// Special case: Can compare integer values regardless of type's sign.
switch {
case k1 == intKind && k2 == uintKind:
truth = v1.Int() >= 0 && uint64(v1.Int()) == v2.Uint()
case k1 == uintKind && k2 == intKind:
truth = v2.Int() >= 0 && v1.Uint() == uint64(v2.Int())
default:
return false, errBadComparison
}
} else {
switch k1 {
case boolKind:
truth = v1.Bool() == v2.Bool()
case complexKind:
truth = v1.Complex() == v2.Complex()
case floatKind:
truth = v1.Float() == v2.Float()
case intKind:
truth = v1.Int() == v2.Int()
case stringKind:
truth = v1.String() == v2.String()
case uintKind:
truth = v1.Uint() == v2.Uint()
default:
panic("invalid kind")
}
}
if truth {
return true, nil
}
}
return false, nil
}
// ne evaluates the comparison a != b.
func ne(arg1, arg2 interface{}) (bool, error) {
// != is the inverse of ==.
equal, err := eq(arg1, arg2)
return !equal, err
}
// lt evaluates the comparison a < b.
func lt(arg1, arg2 interface{}) (bool, error) {
v1 := reflect.ValueOf(arg1)
k1, err := basicKind(v1)
if err != nil {
return false, err
}
v2 := reflect.ValueOf(arg2)
k2, err := basicKind(v2)
if err != nil {
return false, err
}
truth := false
if k1 != k2 {
// Special case: Can compare integer values regardless of type's sign.
switch {
case k1 == intKind && k2 == uintKind:
truth = v1.Int() < 0 || uint64(v1.Int()) < v2.Uint()
case k1 == uintKind && k2 == intKind:
truth = v2.Int() >= 0 && v1.Uint() < uint64(v2.Int())
default:
return false, errBadComparison
}
} else {
switch k1 {
case boolKind, complexKind:
return false, errBadComparisonType
case floatKind:
truth = v1.Float() < v2.Float()
case intKind:
truth = v1.Int() < v2.Int()
case stringKind:
truth = v1.String() < v2.String()
case uintKind:
truth = v1.Uint() < v2.Uint()
default:
panic("invalid kind")
}
}
return truth, nil
}
// le evaluates the comparison <= b.
func le(arg1, arg2 interface{}) (bool, error) {
// <= is < or ==.
lessThan, err := lt(arg1, arg2)
if lessThan || err != nil {
return lessThan, err
}
return eq(arg1, arg2)
}
// gt evaluates the comparison a > b.
func gt(arg1, arg2 interface{}) (bool, error) {
// > is the inverse of <=.
lessOrEqual, err := le(arg1, arg2)
if err != nil {
return false, err
}
return !lessOrEqual, nil
}
// ge evaluates the comparison a >= b.
func ge(arg1, arg2 interface{}) (bool, error) {
// >= is the inverse of <.
lessThan, err := lt(arg1, arg2)
if err != nil {
return false, err
}
return !lessThan, nil
}
// HTML escaping.
var (
htmlQuot = []byte("&#34;") // shorter than "&quot;"
htmlApos = []byte("&#39;") // shorter than "&apos;" and apos was not in HTML until HTML5
htmlAmp = []byte("&amp;")
htmlLt = []byte("&lt;")
htmlGt = []byte("&gt;")
)
// HTMLEscape writes to w the escaped HTML equivalent of the plain text data b.
func HTMLEscape(w io.Writer, b []byte) {
last := 0
for i, c := range b {
var html []byte
switch c {
case '"':
html = htmlQuot
case '\'':
html = htmlApos
case '&':
html = htmlAmp
case '<':
html = htmlLt
case '>':
html = htmlGt
default:
continue
}
w.Write(b[last:i])
w.Write(html)
last = i + 1
}
w.Write(b[last:])
}
// HTMLEscapeString returns the escaped HTML equivalent of the plain text data s.
func HTMLEscapeString(s string) string {
// Avoid allocation if we can.
if strings.IndexAny(s, `'"&<>`) < 0 {
return s
}
var b bytes.Buffer
HTMLEscape(&b, []byte(s))
return b.String()
}
// HTMLEscaper returns the escaped HTML equivalent of the textual
// representation of its arguments.
func HTMLEscaper(args ...interface{}) string {
return HTMLEscapeString(evalArgs(args))
}
// JavaScript escaping.
var (
jsLowUni = []byte(`\u00`)
hex = []byte("0123456789ABCDEF")
jsBackslash = []byte(`\\`)
jsApos = []byte(`\'`)
jsQuot = []byte(`\"`)
jsLt = []byte(`\x3C`)
jsGt = []byte(`\x3E`)
)
// JSEscape writes to w the escaped JavaScript equivalent of the plain text data b.
func JSEscape(w io.Writer, b []byte) {
last := 0
for i := 0; i < len(b); i++ {
c := b[i]
if !jsIsSpecial(rune(c)) {
// fast path: nothing to do
continue
}
w.Write(b[last:i])
if c < utf8.RuneSelf {
// Quotes, slashes and angle brackets get quoted.
// Control characters get written as \u00XX.
switch c {
case '\\':
w.Write(jsBackslash)
case '\'':
w.Write(jsApos)
case '"':
w.Write(jsQuot)
case '<':
w.Write(jsLt)
case '>':
w.Write(jsGt)
default:
w.Write(jsLowUni)
t, b := c>>4, c&0x0f
w.Write(hex[t : t+1])
w.Write(hex[b : b+1])
}
} else {
// Unicode rune.
r, size := utf8.DecodeRune(b[i:])
if unicode.IsPrint(r) {
w.Write(b[i : i+size])
} else {
fmt.Fprintf(w, "\\u%04X", r)
}
i += size - 1
}
last = i + 1
}
w.Write(b[last:])
}
// JSEscapeString returns the escaped JavaScript equivalent of the plain text data s.
func JSEscapeString(s string) string {
// Avoid allocation if we can.
if strings.IndexFunc(s, jsIsSpecial) < 0 {
return s
}
var b bytes.Buffer
JSEscape(&b, []byte(s))
return b.String()
}
func jsIsSpecial(r rune) bool {
switch r {
case '\\', '\'', '"', '<', '>':
return true
}
return r < ' ' || utf8.RuneSelf <= r
}
// JSEscaper returns the escaped JavaScript equivalent of the textual
// representation of its arguments.
func JSEscaper(args ...interface{}) string {
return JSEscapeString(evalArgs(args))
}
// URLQueryEscaper returns the escaped value of the textual representation of
// its arguments in a form suitable for embedding in a URL query.
func URLQueryEscaper(args ...interface{}) string {
return url.QueryEscape(evalArgs(args))
}
// evalArgs formats the list of arguments into a string. It is therefore equivalent to
// fmt.Sprint(args...)
// except that each argument is indirected (if a pointer), as required,
// using the same rules as the default string evaluation during template
// execution.
func evalArgs(args []interface{}) string {
ok := false
var s string
// Fast path for simple common case.
if len(args) == 1 {
s, ok = args[0].(string)
}
if !ok {
for i, arg := range args {
a, ok := printableValue(reflect.ValueOf(arg))
if ok {
args[i] = a
} // else left fmt do its thing
}
s = fmt.Sprint(args...)
}
return s
}

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// Copyright 2011 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
// Helper functions to make constructing templates easier.
package template
import (
"fmt"
"io/ioutil"
"path/filepath"
)
// Functions and methods to parse templates.
// Must is a helper that wraps a call to a function returning (*Template, error)
// and panics if the error is non-nil. It is intended for use in variable
// initializations such as
// var t = template.Must(template.New("name").Parse("text"))
func Must(t *Template, err error) *Template {
if err != nil {
panic(err)
}
return t
}
// ParseFiles creates a new Template and parses the template definitions from
// the named files. The returned template's name will have the (base) name and
// (parsed) contents of the first file. There must be at least one file.
// If an error occurs, parsing stops and the returned *Template is nil.
func ParseFiles(filenames ...string) (*Template, error) {
return parseFiles(nil, filenames...)
}
// ParseFiles parses the named files and associates the resulting templates with
// t. If an error occurs, parsing stops and the returned template is nil;
// otherwise it is t. There must be at least one file.
func (t *Template) ParseFiles(filenames ...string) (*Template, error) {
return parseFiles(t, filenames...)
}
// parseFiles is the helper for the method and function. If the argument
// template is nil, it is created from the first file.
func parseFiles(t *Template, filenames ...string) (*Template, error) {
if len(filenames) == 0 {
// Not really a problem, but be consistent.
return nil, fmt.Errorf("template: no files named in call to ParseFiles")
}
for _, filename := range filenames {
b, err := ioutil.ReadFile(filename)
if err != nil {
return nil, err
}
s := string(b)
name := filepath.Base(filename)
// First template becomes return value if not already defined,
// and we use that one for subsequent New calls to associate
// all the templates together. Also, if this file has the same name
// as t, this file becomes the contents of t, so
// t, err := New(name).Funcs(xxx).ParseFiles(name)
// works. Otherwise we create a new template associated with t.
var tmpl *Template
if t == nil {
t = New(name)
}
if name == t.Name() {
tmpl = t
} else {
tmpl = t.New(name)
}
_, err = tmpl.Parse(s)
if err != nil {
return nil, err
}
}
return t, nil
}
// ParseGlob creates a new Template and parses the template definitions from the
// files identified by the pattern, which must match at least one file. The
// returned template will have the (base) name and (parsed) contents of the
// first file matched by the pattern. ParseGlob is equivalent to calling
// ParseFiles with the list of files matched by the pattern.
func ParseGlob(pattern string) (*Template, error) {
return parseGlob(nil, pattern)
}
// ParseGlob parses the template definitions in the files identified by the
// pattern and associates the resulting templates with t. The pattern is
// processed by filepath.Glob and must match at least one file. ParseGlob is
// equivalent to calling t.ParseFiles with the list of files matched by the
// pattern.
func (t *Template) ParseGlob(pattern string) (*Template, error) {
return parseGlob(t, pattern)
}
// parseGlob is the implementation of the function and method ParseGlob.
func parseGlob(t *Template, pattern string) (*Template, error) {
filenames, err := filepath.Glob(pattern)
if err != nil {
return nil, err
}
if len(filenames) == 0 {
return nil, fmt.Errorf("template: pattern matches no files: %#q", pattern)
}
return parseFiles(t, filenames...)
}

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// Copyright 2011 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
package parse
import (
"fmt"
"strings"
"unicode"
"unicode/utf8"
)
// item represents a token or text string returned from the scanner.
type item struct {
typ itemType // The type of this item.
pos Pos // The starting position, in bytes, of this item in the input string.
val string // The value of this item.
}
func (i item) String() string {
switch {
case i.typ == itemEOF:
return "EOF"
case i.typ == itemError:
return i.val
case i.typ > itemKeyword:
return fmt.Sprintf("<%s>", i.val)
case len(i.val) > 10:
return fmt.Sprintf("%.10q...", i.val)
}
return fmt.Sprintf("%q", i.val)
}
// itemType identifies the type of lex items.
type itemType int
const (
itemError itemType = iota // error occurred; value is text of error
itemBool // boolean constant
itemChar // printable ASCII character; grab bag for comma etc.
itemCharConstant // character constant
itemComplex // complex constant (1+2i); imaginary is just a number
itemColonEquals // colon-equals (':=') introducing a declaration
itemEOF
itemField // alphanumeric identifier starting with '.'
itemIdentifier // alphanumeric identifier not starting with '.'
itemLeftDelim // left action delimiter
itemLeftParen // '(' inside action
itemNumber // simple number, including imaginary
itemPipe // pipe symbol
itemRawString // raw quoted string (includes quotes)
itemRightDelim // right action delimiter
itemElideNewline // elide newline after right delim
itemRightParen // ')' inside action
itemSpace // run of spaces separating arguments
itemString // quoted string (includes quotes)
itemText // plain text
itemVariable // variable starting with '$', such as '$' or '$1' or '$hello'
// Keywords appear after all the rest.
itemKeyword // used only to delimit the keywords
itemDot // the cursor, spelled '.'
itemDefine // define keyword
itemElse // else keyword
itemEnd // end keyword
itemIf // if keyword
itemNil // the untyped nil constant, easiest to treat as a keyword
itemRange // range keyword
itemTemplate // template keyword
itemWith // with keyword
)
var key = map[string]itemType{
".": itemDot,
"define": itemDefine,
"else": itemElse,
"end": itemEnd,
"if": itemIf,
"range": itemRange,
"nil": itemNil,
"template": itemTemplate,
"with": itemWith,
}
const eof = -1
// stateFn represents the state of the scanner as a function that returns the next state.
type stateFn func(*lexer) stateFn
// lexer holds the state of the scanner.
type lexer struct {
name string // the name of the input; used only for error reports
input string // the string being scanned
leftDelim string // start of action
rightDelim string // end of action
state stateFn // the next lexing function to enter
pos Pos // current position in the input
start Pos // start position of this item
width Pos // width of last rune read from input
lastPos Pos // position of most recent item returned by nextItem
items chan item // channel of scanned items
parenDepth int // nesting depth of ( ) exprs
}
// next returns the next rune in the input.
func (l *lexer) next() rune {
if int(l.pos) >= len(l.input) {
l.width = 0
return eof
}
r, w := utf8.DecodeRuneInString(l.input[l.pos:])
l.width = Pos(w)
l.pos += l.width
return r
}
// peek returns but does not consume the next rune in the input.
func (l *lexer) peek() rune {
r := l.next()
l.backup()
return r
}
// backup steps back one rune. Can only be called once per call of next.
func (l *lexer) backup() {
l.pos -= l.width
}
// emit passes an item back to the client.
func (l *lexer) emit(t itemType) {
l.items <- item{t, l.start, l.input[l.start:l.pos]}
l.start = l.pos
}
// ignore skips over the pending input before this point.
func (l *lexer) ignore() {
l.start = l.pos
}
// accept consumes the next rune if it's from the valid set.
func (l *lexer) accept(valid string) bool {
if strings.IndexRune(valid, l.next()) >= 0 {
return true
}
l.backup()
return false
}
// acceptRun consumes a run of runes from the valid set.
func (l *lexer) acceptRun(valid string) {
for strings.IndexRune(valid, l.next()) >= 0 {
}
l.backup()
}
// lineNumber reports which line we're on, based on the position of
// the previous item returned by nextItem. Doing it this way
// means we don't have to worry about peek double counting.
func (l *lexer) lineNumber() int {
return 1 + strings.Count(l.input[:l.lastPos], "\n")
}
// errorf returns an error token and terminates the scan by passing
// back a nil pointer that will be the next state, terminating l.nextItem.
func (l *lexer) errorf(format string, args ...interface{}) stateFn {
l.items <- item{itemError, l.start, fmt.Sprintf(format, args...)}
return nil
}
// nextItem returns the next item from the input.
func (l *lexer) nextItem() item {
item := <-l.items
l.lastPos = item.pos
return item
}
// lex creates a new scanner for the input string.
func lex(name, input, left, right string) *lexer {
if left == "" {
left = leftDelim
}
if right == "" {
right = rightDelim
}
l := &lexer{
name: name,
input: input,
leftDelim: left,
rightDelim: right,
items: make(chan item),
}
go l.run()
return l
}
// run runs the state machine for the lexer.
func (l *lexer) run() {
for l.state = lexText; l.state != nil; {
l.state = l.state(l)
}
}
// state functions
const (
leftDelim = "{{"
rightDelim = "}}"
leftComment = "/*"
rightComment = "*/"
)
// lexText scans until an opening action delimiter, "{{".
func lexText(l *lexer) stateFn {
for {
if strings.HasPrefix(l.input[l.pos:], l.leftDelim) {
if l.pos > l.start {
l.emit(itemText)
}
return lexLeftDelim
}
if l.next() == eof {
break
}
}
// Correctly reached EOF.
if l.pos > l.start {
l.emit(itemText)
}
l.emit(itemEOF)
return nil
}
// lexLeftDelim scans the left delimiter, which is known to be present.
func lexLeftDelim(l *lexer) stateFn {
l.pos += Pos(len(l.leftDelim))
if strings.HasPrefix(l.input[l.pos:], leftComment) {
return lexComment
}
l.emit(itemLeftDelim)
l.parenDepth = 0
return lexInsideAction
}
// lexComment scans a comment. The left comment marker is known to be present.
func lexComment(l *lexer) stateFn {
l.pos += Pos(len(leftComment))
i := strings.Index(l.input[l.pos:], rightComment)
if i < 0 {
return l.errorf("unclosed comment")
}
l.pos += Pos(i + len(rightComment))
if !strings.HasPrefix(l.input[l.pos:], l.rightDelim) {
return l.errorf("comment ends before closing delimiter")
}
l.pos += Pos(len(l.rightDelim))
l.ignore()
return lexText
}
// lexRightDelim scans the right delimiter, which is known to be present.
func lexRightDelim(l *lexer) stateFn {
l.pos += Pos(len(l.rightDelim))
l.emit(itemRightDelim)
if l.peek() == '\\' {
l.pos++
l.emit(itemElideNewline)
}
return lexText
}
// lexInsideAction scans the elements inside action delimiters.
func lexInsideAction(l *lexer) stateFn {
// Either number, quoted string, or identifier.
// Spaces separate arguments; runs of spaces turn into itemSpace.
// Pipe symbols separate and are emitted.
if strings.HasPrefix(l.input[l.pos:], l.rightDelim+"\\") || strings.HasPrefix(l.input[l.pos:], l.rightDelim) {
if l.parenDepth == 0 {
return lexRightDelim
}
return l.errorf("unclosed left paren")
}
switch r := l.next(); {
case r == eof || isEndOfLine(r):
return l.errorf("unclosed action")
case isSpace(r):
return lexSpace
case r == ':':
if l.next() != '=' {
return l.errorf("expected :=")
}
l.emit(itemColonEquals)
case r == '|':
l.emit(itemPipe)
case r == '"':
return lexQuote
case r == '`':
return lexRawQuote
case r == '$':
return lexVariable
case r == '\'':
return lexChar
case r == '.':
// special look-ahead for ".field" so we don't break l.backup().
if l.pos < Pos(len(l.input)) {
r := l.input[l.pos]
if r < '0' || '9' < r {
return lexField
}
}
fallthrough // '.' can start a number.
case r == '+' || r == '-' || ('0' <= r && r <= '9'):
l.backup()
return lexNumber
case isAlphaNumeric(r):
l.backup()
return lexIdentifier
case r == '(':
l.emit(itemLeftParen)
l.parenDepth++
return lexInsideAction
case r == ')':
l.emit(itemRightParen)
l.parenDepth--
if l.parenDepth < 0 {
return l.errorf("unexpected right paren %#U", r)
}
return lexInsideAction
case r <= unicode.MaxASCII && unicode.IsPrint(r):
l.emit(itemChar)
return lexInsideAction
default:
return l.errorf("unrecognized character in action: %#U", r)
}
return lexInsideAction
}
// lexSpace scans a run of space characters.
// One space has already been seen.
func lexSpace(l *lexer) stateFn {
for isSpace(l.peek()) {
l.next()
}
l.emit(itemSpace)
return lexInsideAction
}
// lexIdentifier scans an alphanumeric.
func lexIdentifier(l *lexer) stateFn {
Loop:
for {
switch r := l.next(); {
case isAlphaNumeric(r):
// absorb.
default:
l.backup()
word := l.input[l.start:l.pos]
if !l.atTerminator() {
return l.errorf("bad character %#U", r)
}
switch {
case key[word] > itemKeyword:
l.emit(key[word])
case word[0] == '.':
l.emit(itemField)
case word == "true", word == "false":
l.emit(itemBool)
default:
l.emit(itemIdentifier)
}
break Loop
}
}
return lexInsideAction
}
// lexField scans a field: .Alphanumeric.
// The . has been scanned.
func lexField(l *lexer) stateFn {
return lexFieldOrVariable(l, itemField)
}
// lexVariable scans a Variable: $Alphanumeric.
// The $ has been scanned.
func lexVariable(l *lexer) stateFn {
if l.atTerminator() { // Nothing interesting follows -> "$".
l.emit(itemVariable)
return lexInsideAction
}
return lexFieldOrVariable(l, itemVariable)
}
// lexVariable scans a field or variable: [.$]Alphanumeric.
// The . or $ has been scanned.
func lexFieldOrVariable(l *lexer, typ itemType) stateFn {
if l.atTerminator() { // Nothing interesting follows -> "." or "$".
if typ == itemVariable {
l.emit(itemVariable)
} else {
l.emit(itemDot)
}
return lexInsideAction
}
var r rune
for {
r = l.next()
if !isAlphaNumeric(r) {
l.backup()
break
}
}
if !l.atTerminator() {
return l.errorf("bad character %#U", r)
}
l.emit(typ)
return lexInsideAction
}
// atTerminator reports whether the input is at valid termination character to
// appear after an identifier. Breaks .X.Y into two pieces. Also catches cases
// like "$x+2" not being acceptable without a space, in case we decide one
// day to implement arithmetic.
func (l *lexer) atTerminator() bool {
r := l.peek()
if isSpace(r) || isEndOfLine(r) {
return true
}
switch r {
case eof, '.', ',', '|', ':', ')', '(':
return true
}
// Does r start the delimiter? This can be ambiguous (with delim=="//", $x/2 will
// succeed but should fail) but only in extremely rare cases caused by willfully
// bad choice of delimiter.
if rd, _ := utf8.DecodeRuneInString(l.rightDelim); rd == r {
return true
}
return false
}
// lexChar scans a character constant. The initial quote is already
// scanned. Syntax checking is done by the parser.
func lexChar(l *lexer) stateFn {
Loop:
for {
switch l.next() {
case '\\':
if r := l.next(); r != eof && r != '\n' {
break
}
fallthrough
case eof, '\n':
return l.errorf("unterminated character constant")
case '\'':
break Loop
}
}
l.emit(itemCharConstant)
return lexInsideAction
}
// lexNumber scans a number: decimal, octal, hex, float, or imaginary. This
// isn't a perfect number scanner - for instance it accepts "." and "0x0.2"
// and "089" - but when it's wrong the input is invalid and the parser (via
// strconv) will notice.
func lexNumber(l *lexer) stateFn {
if !l.scanNumber() {
return l.errorf("bad number syntax: %q", l.input[l.start:l.pos])
}
if sign := l.peek(); sign == '+' || sign == '-' {
// Complex: 1+2i. No spaces, must end in 'i'.
if !l.scanNumber() || l.input[l.pos-1] != 'i' {
return l.errorf("bad number syntax: %q", l.input[l.start:l.pos])
}
l.emit(itemComplex)
} else {
l.emit(itemNumber)
}
return lexInsideAction
}
func (l *lexer) scanNumber() bool {
// Optional leading sign.
l.accept("+-")
// Is it hex?
digits := "0123456789"
if l.accept("0") && l.accept("xX") {
digits = "0123456789abcdefABCDEF"
}
l.acceptRun(digits)
if l.accept(".") {
l.acceptRun(digits)
}
if l.accept("eE") {
l.accept("+-")
l.acceptRun("0123456789")
}
// Is it imaginary?
l.accept("i")
// Next thing mustn't be alphanumeric.
if isAlphaNumeric(l.peek()) {
l.next()
return false
}
return true
}
// lexQuote scans a quoted string.
func lexQuote(l *lexer) stateFn {
Loop:
for {
switch l.next() {
case '\\':
if r := l.next(); r != eof && r != '\n' {
break
}
fallthrough
case eof, '\n':
return l.errorf("unterminated quoted string")
case '"':
break Loop
}
}
l.emit(itemString)
return lexInsideAction
}
// lexRawQuote scans a raw quoted string.
func lexRawQuote(l *lexer) stateFn {
Loop:
for {
switch l.next() {
case eof, '\n':
return l.errorf("unterminated raw quoted string")
case '`':
break Loop
}
}
l.emit(itemRawString)
return lexInsideAction
}
// isSpace reports whether r is a space character.
func isSpace(r rune) bool {
return r == ' ' || r == '\t'
}
// isEndOfLine reports whether r is an end-of-line character.
func isEndOfLine(r rune) bool {
return r == '\r' || r == '\n'
}
// isAlphaNumeric reports whether r is an alphabetic, digit, or underscore.
func isAlphaNumeric(r rune) bool {
return r == '_' || unicode.IsLetter(r) || unicode.IsDigit(r)
}

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@ -0,0 +1,834 @@
// Copyright 2011 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
// Parse nodes.
package parse
import (
"bytes"
"fmt"
"strconv"
"strings"
)
var textFormat = "%s" // Changed to "%q" in tests for better error messages.
// A Node is an element in the parse tree. The interface is trivial.
// The interface contains an unexported method so that only
// types local to this package can satisfy it.
type Node interface {
Type() NodeType
String() string
// Copy does a deep copy of the Node and all its components.
// To avoid type assertions, some XxxNodes also have specialized
// CopyXxx methods that return *XxxNode.
Copy() Node
Position() Pos // byte position of start of node in full original input string
// tree returns the containing *Tree.
// It is unexported so all implementations of Node are in this package.
tree() *Tree
}
// NodeType identifies the type of a parse tree node.
type NodeType int
// Pos represents a byte position in the original input text from which
// this template was parsed.
type Pos int
func (p Pos) Position() Pos {
return p
}
// Type returns itself and provides an easy default implementation
// for embedding in a Node. Embedded in all non-trivial Nodes.
func (t NodeType) Type() NodeType {
return t
}
const (
NodeText NodeType = iota // Plain text.
NodeAction // A non-control action such as a field evaluation.
NodeBool // A boolean constant.
NodeChain // A sequence of field accesses.
NodeCommand // An element of a pipeline.
NodeDot // The cursor, dot.
nodeElse // An else action. Not added to tree.
nodeEnd // An end action. Not added to tree.
NodeField // A field or method name.
NodeIdentifier // An identifier; always a function name.
NodeIf // An if action.
NodeList // A list of Nodes.
NodeNil // An untyped nil constant.
NodeNumber // A numerical constant.
NodePipe // A pipeline of commands.
NodeRange // A range action.
NodeString // A string constant.
NodeTemplate // A template invocation action.
NodeVariable // A $ variable.
NodeWith // A with action.
)
// Nodes.
// ListNode holds a sequence of nodes.
type ListNode struct {
NodeType
Pos
tr *Tree
Nodes []Node // The element nodes in lexical order.
}
func (t *Tree) newList(pos Pos) *ListNode {
return &ListNode{tr: t, NodeType: NodeList, Pos: pos}
}
func (l *ListNode) append(n Node) {
l.Nodes = append(l.Nodes, n)
}
func (l *ListNode) tree() *Tree {
return l.tr
}
func (l *ListNode) String() string {
b := new(bytes.Buffer)
for _, n := range l.Nodes {
fmt.Fprint(b, n)
}
return b.String()
}
func (l *ListNode) CopyList() *ListNode {
if l == nil {
return l
}
n := l.tr.newList(l.Pos)
for _, elem := range l.Nodes {
n.append(elem.Copy())
}
return n
}
func (l *ListNode) Copy() Node {
return l.CopyList()
}
// TextNode holds plain text.
type TextNode struct {
NodeType
Pos
tr *Tree
Text []byte // The text; may span newlines.
}
func (t *Tree) newText(pos Pos, text string) *TextNode {
return &TextNode{tr: t, NodeType: NodeText, Pos: pos, Text: []byte(text)}
}
func (t *TextNode) String() string {
return fmt.Sprintf(textFormat, t.Text)
}
func (t *TextNode) tree() *Tree {
return t.tr
}
func (t *TextNode) Copy() Node {
return &TextNode{tr: t.tr, NodeType: NodeText, Pos: t.Pos, Text: append([]byte{}, t.Text...)}
}
// PipeNode holds a pipeline with optional declaration
type PipeNode struct {
NodeType
Pos
tr *Tree
Line int // The line number in the input (deprecated; kept for compatibility)
Decl []*VariableNode // Variable declarations in lexical order.
Cmds []*CommandNode // The commands in lexical order.
}
func (t *Tree) newPipeline(pos Pos, line int, decl []*VariableNode) *PipeNode {
return &PipeNode{tr: t, NodeType: NodePipe, Pos: pos, Line: line, Decl: decl}
}
func (p *PipeNode) append(command *CommandNode) {
p.Cmds = append(p.Cmds, command)
}
func (p *PipeNode) String() string {
s := ""
if len(p.Decl) > 0 {
for i, v := range p.Decl {
if i > 0 {
s += ", "
}
s += v.String()
}
s += " := "
}
for i, c := range p.Cmds {
if i > 0 {
s += " | "
}
s += c.String()
}
return s
}
func (p *PipeNode) tree() *Tree {
return p.tr
}
func (p *PipeNode) CopyPipe() *PipeNode {
if p == nil {
return p
}
var decl []*VariableNode
for _, d := range p.Decl {
decl = append(decl, d.Copy().(*VariableNode))
}
n := p.tr.newPipeline(p.Pos, p.Line, decl)
for _, c := range p.Cmds {
n.append(c.Copy().(*CommandNode))
}
return n
}
func (p *PipeNode) Copy() Node {
return p.CopyPipe()
}
// ActionNode holds an action (something bounded by delimiters).
// Control actions have their own nodes; ActionNode represents simple
// ones such as field evaluations and parenthesized pipelines.
type ActionNode struct {
NodeType
Pos
tr *Tree
Line int // The line number in the input (deprecated; kept for compatibility)
Pipe *PipeNode // The pipeline in the action.
}
func (t *Tree) newAction(pos Pos, line int, pipe *PipeNode) *ActionNode {
return &ActionNode{tr: t, NodeType: NodeAction, Pos: pos, Line: line, Pipe: pipe}
}
func (a *ActionNode) String() string {
return fmt.Sprintf("{{%s}}", a.Pipe)
}
func (a *ActionNode) tree() *Tree {
return a.tr
}
func (a *ActionNode) Copy() Node {
return a.tr.newAction(a.Pos, a.Line, a.Pipe.CopyPipe())
}
// CommandNode holds a command (a pipeline inside an evaluating action).
type CommandNode struct {
NodeType
Pos
tr *Tree
Args []Node // Arguments in lexical order: Identifier, field, or constant.
}
func (t *Tree) newCommand(pos Pos) *CommandNode {
return &CommandNode{tr: t, NodeType: NodeCommand, Pos: pos}
}
func (c *CommandNode) append(arg Node) {
c.Args = append(c.Args, arg)
}
func (c *CommandNode) String() string {
s := ""
for i, arg := range c.Args {
if i > 0 {
s += " "
}
if arg, ok := arg.(*PipeNode); ok {
s += "(" + arg.String() + ")"
continue
}
s += arg.String()
}
return s
}
func (c *CommandNode) tree() *Tree {
return c.tr
}
func (c *CommandNode) Copy() Node {
if c == nil {
return c
}
n := c.tr.newCommand(c.Pos)
for _, c := range c.Args {
n.append(c.Copy())
}
return n
}
// IdentifierNode holds an identifier.
type IdentifierNode struct {
NodeType
Pos
tr *Tree
Ident string // The identifier's name.
}
// NewIdentifier returns a new IdentifierNode with the given identifier name.
func NewIdentifier(ident string) *IdentifierNode {
return &IdentifierNode{NodeType: NodeIdentifier, Ident: ident}
}
// SetPos sets the position. NewIdentifier is a public method so we can't modify its signature.
// Chained for convenience.
// TODO: fix one day?
func (i *IdentifierNode) SetPos(pos Pos) *IdentifierNode {
i.Pos = pos
return i
}
// SetTree sets the parent tree for the node. NewIdentifier is a public method so we can't modify its signature.
// Chained for convenience.
// TODO: fix one day?
func (i *IdentifierNode) SetTree(t *Tree) *IdentifierNode {
i.tr = t
return i
}
func (i *IdentifierNode) String() string {
return i.Ident
}
func (i *IdentifierNode) tree() *Tree {
return i.tr
}
func (i *IdentifierNode) Copy() Node {
return NewIdentifier(i.Ident).SetTree(i.tr).SetPos(i.Pos)
}
// VariableNode holds a list of variable names, possibly with chained field
// accesses. The dollar sign is part of the (first) name.
type VariableNode struct {
NodeType
Pos
tr *Tree
Ident []string // Variable name and fields in lexical order.
}
func (t *Tree) newVariable(pos Pos, ident string) *VariableNode {
return &VariableNode{tr: t, NodeType: NodeVariable, Pos: pos, Ident: strings.Split(ident, ".")}
}
func (v *VariableNode) String() string {
s := ""
for i, id := range v.Ident {
if i > 0 {
s += "."
}
s += id
}
return s
}
func (v *VariableNode) tree() *Tree {
return v.tr
}
func (v *VariableNode) Copy() Node {
return &VariableNode{tr: v.tr, NodeType: NodeVariable, Pos: v.Pos, Ident: append([]string{}, v.Ident...)}
}
// DotNode holds the special identifier '.'.
type DotNode struct {
NodeType
Pos
tr *Tree
}
func (t *Tree) newDot(pos Pos) *DotNode {
return &DotNode{tr: t, NodeType: NodeDot, Pos: pos}
}
func (d *DotNode) Type() NodeType {
// Override method on embedded NodeType for API compatibility.
// TODO: Not really a problem; could change API without effect but
// api tool complains.
return NodeDot
}
func (d *DotNode) String() string {
return "."
}
func (d *DotNode) tree() *Tree {
return d.tr
}
func (d *DotNode) Copy() Node {
return d.tr.newDot(d.Pos)
}
// NilNode holds the special identifier 'nil' representing an untyped nil constant.
type NilNode struct {
NodeType
Pos
tr *Tree
}
func (t *Tree) newNil(pos Pos) *NilNode {
return &NilNode{tr: t, NodeType: NodeNil, Pos: pos}
}
func (n *NilNode) Type() NodeType {
// Override method on embedded NodeType for API compatibility.
// TODO: Not really a problem; could change API without effect but
// api tool complains.
return NodeNil
}
func (n *NilNode) String() string {
return "nil"
}
func (n *NilNode) tree() *Tree {
return n.tr
}
func (n *NilNode) Copy() Node {
return n.tr.newNil(n.Pos)
}
// FieldNode holds a field (identifier starting with '.').
// The names may be chained ('.x.y').
// The period is dropped from each ident.
type FieldNode struct {
NodeType
Pos
tr *Tree
Ident []string // The identifiers in lexical order.
}
func (t *Tree) newField(pos Pos, ident string) *FieldNode {
return &FieldNode{tr: t, NodeType: NodeField, Pos: pos, Ident: strings.Split(ident[1:], ".")} // [1:] to drop leading period
}
func (f *FieldNode) String() string {
s := ""
for _, id := range f.Ident {
s += "." + id
}
return s
}
func (f *FieldNode) tree() *Tree {
return f.tr
}
func (f *FieldNode) Copy() Node {
return &FieldNode{tr: f.tr, NodeType: NodeField, Pos: f.Pos, Ident: append([]string{}, f.Ident...)}
}
// ChainNode holds a term followed by a chain of field accesses (identifier starting with '.').
// The names may be chained ('.x.y').
// The periods are dropped from each ident.
type ChainNode struct {
NodeType
Pos
tr *Tree
Node Node
Field []string // The identifiers in lexical order.
}
func (t *Tree) newChain(pos Pos, node Node) *ChainNode {
return &ChainNode{tr: t, NodeType: NodeChain, Pos: pos, Node: node}
}
// Add adds the named field (which should start with a period) to the end of the chain.
func (c *ChainNode) Add(field string) {
if len(field) == 0 || field[0] != '.' {
panic("no dot in field")
}
field = field[1:] // Remove leading dot.
if field == "" {
panic("empty field")
}
c.Field = append(c.Field, field)
}
func (c *ChainNode) String() string {
s := c.Node.String()
if _, ok := c.Node.(*PipeNode); ok {
s = "(" + s + ")"
}
for _, field := range c.Field {
s += "." + field
}
return s
}
func (c *ChainNode) tree() *Tree {
return c.tr
}
func (c *ChainNode) Copy() Node {
return &ChainNode{tr: c.tr, NodeType: NodeChain, Pos: c.Pos, Node: c.Node, Field: append([]string{}, c.Field...)}
}
// BoolNode holds a boolean constant.
type BoolNode struct {
NodeType
Pos
tr *Tree
True bool // The value of the boolean constant.
}
func (t *Tree) newBool(pos Pos, true bool) *BoolNode {
return &BoolNode{tr: t, NodeType: NodeBool, Pos: pos, True: true}
}
func (b *BoolNode) String() string {
if b.True {
return "true"
}
return "false"
}
func (b *BoolNode) tree() *Tree {
return b.tr
}
func (b *BoolNode) Copy() Node {
return b.tr.newBool(b.Pos, b.True)
}
// NumberNode holds a number: signed or unsigned integer, float, or complex.
// The value is parsed and stored under all the types that can represent the value.
// This simulates in a small amount of code the behavior of Go's ideal constants.
type NumberNode struct {
NodeType
Pos
tr *Tree
IsInt bool // Number has an integral value.
IsUint bool // Number has an unsigned integral value.
IsFloat bool // Number has a floating-point value.
IsComplex bool // Number is complex.
Int64 int64 // The signed integer value.
Uint64 uint64 // The unsigned integer value.
Float64 float64 // The floating-point value.
Complex128 complex128 // The complex value.
Text string // The original textual representation from the input.
}
func (t *Tree) newNumber(pos Pos, text string, typ itemType) (*NumberNode, error) {
n := &NumberNode{tr: t, NodeType: NodeNumber, Pos: pos, Text: text}
switch typ {
case itemCharConstant:
rune, _, tail, err := strconv.UnquoteChar(text[1:], text[0])
if err != nil {
return nil, err
}
if tail != "'" {
return nil, fmt.Errorf("malformed character constant: %s", text)
}
n.Int64 = int64(rune)
n.IsInt = true
n.Uint64 = uint64(rune)
n.IsUint = true
n.Float64 = float64(rune) // odd but those are the rules.
n.IsFloat = true
return n, nil
case itemComplex:
// fmt.Sscan can parse the pair, so let it do the work.
if _, err := fmt.Sscan(text, &n.Complex128); err != nil {
return nil, err
}
n.IsComplex = true
n.simplifyComplex()
return n, nil
}
// Imaginary constants can only be complex unless they are zero.
if len(text) > 0 && text[len(text)-1] == 'i' {
f, err := strconv.ParseFloat(text[:len(text)-1], 64)
if err == nil {
n.IsComplex = true
n.Complex128 = complex(0, f)
n.simplifyComplex()
return n, nil
}
}
// Do integer test first so we get 0x123 etc.
u, err := strconv.ParseUint(text, 0, 64) // will fail for -0; fixed below.
if err == nil {
n.IsUint = true
n.Uint64 = u
}
i, err := strconv.ParseInt(text, 0, 64)
if err == nil {
n.IsInt = true
n.Int64 = i
if i == 0 {
n.IsUint = true // in case of -0.
n.Uint64 = u
}
}
// If an integer extraction succeeded, promote the float.
if n.IsInt {
n.IsFloat = true
n.Float64 = float64(n.Int64)
} else if n.IsUint {
n.IsFloat = true
n.Float64 = float64(n.Uint64)
} else {
f, err := strconv.ParseFloat(text, 64)
if err == nil {
n.IsFloat = true
n.Float64 = f
// If a floating-point extraction succeeded, extract the int if needed.
if !n.IsInt && float64(int64(f)) == f {
n.IsInt = true
n.Int64 = int64(f)
}
if !n.IsUint && float64(uint64(f)) == f {
n.IsUint = true
n.Uint64 = uint64(f)
}
}
}
if !n.IsInt && !n.IsUint && !n.IsFloat {
return nil, fmt.Errorf("illegal number syntax: %q", text)
}
return n, nil
}
// simplifyComplex pulls out any other types that are represented by the complex number.
// These all require that the imaginary part be zero.
func (n *NumberNode) simplifyComplex() {
n.IsFloat = imag(n.Complex128) == 0
if n.IsFloat {
n.Float64 = real(n.Complex128)
n.IsInt = float64(int64(n.Float64)) == n.Float64
if n.IsInt {
n.Int64 = int64(n.Float64)
}
n.IsUint = float64(uint64(n.Float64)) == n.Float64
if n.IsUint {
n.Uint64 = uint64(n.Float64)
}
}
}
func (n *NumberNode) String() string {
return n.Text
}
func (n *NumberNode) tree() *Tree {
return n.tr
}
func (n *NumberNode) Copy() Node {
nn := new(NumberNode)
*nn = *n // Easy, fast, correct.
return nn
}
// StringNode holds a string constant. The value has been "unquoted".
type StringNode struct {
NodeType
Pos
tr *Tree
Quoted string // The original text of the string, with quotes.
Text string // The string, after quote processing.
}
func (t *Tree) newString(pos Pos, orig, text string) *StringNode {
return &StringNode{tr: t, NodeType: NodeString, Pos: pos, Quoted: orig, Text: text}
}
func (s *StringNode) String() string {
return s.Quoted
}
func (s *StringNode) tree() *Tree {
return s.tr
}
func (s *StringNode) Copy() Node {
return s.tr.newString(s.Pos, s.Quoted, s.Text)
}
// endNode represents an {{end}} action.
// It does not appear in the final parse tree.
type endNode struct {
NodeType
Pos
tr *Tree
}
func (t *Tree) newEnd(pos Pos) *endNode {
return &endNode{tr: t, NodeType: nodeEnd, Pos: pos}
}
func (e *endNode) String() string {
return "{{end}}"
}
func (e *endNode) tree() *Tree {
return e.tr
}
func (e *endNode) Copy() Node {
return e.tr.newEnd(e.Pos)
}
// elseNode represents an {{else}} action. Does not appear in the final tree.
type elseNode struct {
NodeType
Pos
tr *Tree
Line int // The line number in the input (deprecated; kept for compatibility)
}
func (t *Tree) newElse(pos Pos, line int) *elseNode {
return &elseNode{tr: t, NodeType: nodeElse, Pos: pos, Line: line}
}
func (e *elseNode) Type() NodeType {
return nodeElse
}
func (e *elseNode) String() string {
return "{{else}}"
}
func (e *elseNode) tree() *Tree {
return e.tr
}
func (e *elseNode) Copy() Node {
return e.tr.newElse(e.Pos, e.Line)
}
// BranchNode is the common representation of if, range, and with.
type BranchNode struct {
NodeType
Pos
tr *Tree
Line int // The line number in the input (deprecated; kept for compatibility)
Pipe *PipeNode // The pipeline to be evaluated.
List *ListNode // What to execute if the value is non-empty.
ElseList *ListNode // What to execute if the value is empty (nil if absent).
}
func (b *BranchNode) String() string {
name := ""
switch b.NodeType {
case NodeIf:
name = "if"
case NodeRange:
name = "range"
case NodeWith:
name = "with"
default:
panic("unknown branch type")
}
if b.ElseList != nil {
return fmt.Sprintf("{{%s %s}}%s{{else}}%s{{end}}", name, b.Pipe, b.List, b.ElseList)
}
return fmt.Sprintf("{{%s %s}}%s{{end}}", name, b.Pipe, b.List)
}
func (b *BranchNode) tree() *Tree {
return b.tr
}
func (b *BranchNode) Copy() Node {
switch b.NodeType {
case NodeIf:
return b.tr.newIf(b.Pos, b.Line, b.Pipe, b.List, b.ElseList)
case NodeRange:
return b.tr.newRange(b.Pos, b.Line, b.Pipe, b.List, b.ElseList)
case NodeWith:
return b.tr.newWith(b.Pos, b.Line, b.Pipe, b.List, b.ElseList)
default:
panic("unknown branch type")
}
}
// IfNode represents an {{if}} action and its commands.
type IfNode struct {
BranchNode
}
func (t *Tree) newIf(pos Pos, line int, pipe *PipeNode, list, elseList *ListNode) *IfNode {
return &IfNode{BranchNode{tr: t, NodeType: NodeIf, Pos: pos, Line: line, Pipe: pipe, List: list, ElseList: elseList}}
}
func (i *IfNode) Copy() Node {
return i.tr.newIf(i.Pos, i.Line, i.Pipe.CopyPipe(), i.List.CopyList(), i.ElseList.CopyList())
}
// RangeNode represents a {{range}} action and its commands.
type RangeNode struct {
BranchNode
}
func (t *Tree) newRange(pos Pos, line int, pipe *PipeNode, list, elseList *ListNode) *RangeNode {
return &RangeNode{BranchNode{tr: t, NodeType: NodeRange, Pos: pos, Line: line, Pipe: pipe, List: list, ElseList: elseList}}
}
func (r *RangeNode) Copy() Node {
return r.tr.newRange(r.Pos, r.Line, r.Pipe.CopyPipe(), r.List.CopyList(), r.ElseList.CopyList())
}
// WithNode represents a {{with}} action and its commands.
type WithNode struct {
BranchNode
}
func (t *Tree) newWith(pos Pos, line int, pipe *PipeNode, list, elseList *ListNode) *WithNode {
return &WithNode{BranchNode{tr: t, NodeType: NodeWith, Pos: pos, Line: line, Pipe: pipe, List: list, ElseList: elseList}}
}
func (w *WithNode) Copy() Node {
return w.tr.newWith(w.Pos, w.Line, w.Pipe.CopyPipe(), w.List.CopyList(), w.ElseList.CopyList())
}
// TemplateNode represents a {{template}} action.
type TemplateNode struct {
NodeType
Pos
tr *Tree
Line int // The line number in the input (deprecated; kept for compatibility)
Name string // The name of the template (unquoted).
Pipe *PipeNode // The command to evaluate as dot for the template.
}
func (t *Tree) newTemplate(pos Pos, line int, name string, pipe *PipeNode) *TemplateNode {
return &TemplateNode{tr: t, NodeType: NodeTemplate, Pos: pos, Line: line, Name: name, Pipe: pipe}
}
func (t *TemplateNode) String() string {
if t.Pipe == nil {
return fmt.Sprintf("{{template %q}}", t.Name)
}
return fmt.Sprintf("{{template %q %s}}", t.Name, t.Pipe)
}
func (t *TemplateNode) tree() *Tree {
return t.tr
}
func (t *TemplateNode) Copy() Node {
return t.tr.newTemplate(t.Pos, t.Line, t.Name, t.Pipe.CopyPipe())
}

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// Copyright 2011 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
// Package parse builds parse trees for templates as defined by text/template
// and html/template. Clients should use those packages to construct templates
// rather than this one, which provides shared internal data structures not
// intended for general use.
package parse
import (
"bytes"
"fmt"
"runtime"
"strconv"
"strings"
)
// Tree is the representation of a single parsed template.
type Tree struct {
Name string // name of the template represented by the tree.
ParseName string // name of the top-level template during parsing, for error messages.
Root *ListNode // top-level root of the tree.
text string // text parsed to create the template (or its parent)
// Parsing only; cleared after parse.
funcs []map[string]interface{}
lex *lexer
token [3]item // three-token lookahead for parser.
peekCount int
vars []string // variables defined at the moment.
}
// Copy returns a copy of the Tree. Any parsing state is discarded.
func (t *Tree) Copy() *Tree {
if t == nil {
return nil
}
return &Tree{
Name: t.Name,
ParseName: t.ParseName,
Root: t.Root.CopyList(),
text: t.text,
}
}
// Parse returns a map from template name to parse.Tree, created by parsing the
// templates described in the argument string. The top-level template will be
// given the specified name. If an error is encountered, parsing stops and an
// empty map is returned with the error.
func Parse(name, text, leftDelim, rightDelim string, funcs ...map[string]interface{}) (treeSet map[string]*Tree, err error) {
treeSet = make(map[string]*Tree)
t := New(name)
t.text = text
_, err = t.Parse(text, leftDelim, rightDelim, treeSet, funcs...)
return
}
// next returns the next token.
func (t *Tree) next() item {
if t.peekCount > 0 {
t.peekCount--
} else {
t.token[0] = t.lex.nextItem()
}
return t.token[t.peekCount]
}
// backup backs the input stream up one token.
func (t *Tree) backup() {
t.peekCount++
}
// backup2 backs the input stream up two tokens.
// The zeroth token is already there.
func (t *Tree) backup2(t1 item) {
t.token[1] = t1
t.peekCount = 2
}
// backup3 backs the input stream up three tokens
// The zeroth token is already there.
func (t *Tree) backup3(t2, t1 item) { // Reverse order: we're pushing back.
t.token[1] = t1
t.token[2] = t2
t.peekCount = 3
}
// peek returns but does not consume the next token.
func (t *Tree) peek() item {
if t.peekCount > 0 {
return t.token[t.peekCount-1]
}
t.peekCount = 1
t.token[0] = t.lex.nextItem()
return t.token[0]
}
// nextNonSpace returns the next non-space token.
func (t *Tree) nextNonSpace() (token item) {
for {
token = t.next()
if token.typ != itemSpace {
break
}
}
return token
}
// peekNonSpace returns but does not consume the next non-space token.
func (t *Tree) peekNonSpace() (token item) {
for {
token = t.next()
if token.typ != itemSpace {
break
}
}
t.backup()
return token
}
// Parsing.
// New allocates a new parse tree with the given name.
func New(name string, funcs ...map[string]interface{}) *Tree {
return &Tree{
Name: name,
funcs: funcs,
}
}
// ErrorContext returns a textual representation of the location of the node in the input text.
// The receiver is only used when the node does not have a pointer to the tree inside,
// which can occur in old code.
func (t *Tree) ErrorContext(n Node) (location, context string) {
pos := int(n.Position())
tree := n.tree()
if tree == nil {
tree = t
}
text := tree.text[:pos]
byteNum := strings.LastIndex(text, "\n")
if byteNum == -1 {
byteNum = pos // On first line.
} else {
byteNum++ // After the newline.
byteNum = pos - byteNum
}
lineNum := 1 + strings.Count(text, "\n")
context = n.String()
if len(context) > 20 {
context = fmt.Sprintf("%.20s...", context)
}
return fmt.Sprintf("%s:%d:%d", tree.ParseName, lineNum, byteNum), context
}
// errorf formats the error and terminates processing.
func (t *Tree) errorf(format string, args ...interface{}) {
t.Root = nil
format = fmt.Sprintf("template: %s:%d: %s", t.ParseName, t.lex.lineNumber(), format)
panic(fmt.Errorf(format, args...))
}
// error terminates processing.
func (t *Tree) error(err error) {
t.errorf("%s", err)
}
// expect consumes the next token and guarantees it has the required type.
func (t *Tree) expect(expected itemType, context string) item {
token := t.nextNonSpace()
if token.typ != expected {
t.unexpected(token, context)
}
return token
}
// expectOneOf consumes the next token and guarantees it has one of the required types.
func (t *Tree) expectOneOf(expected1, expected2 itemType, context string) item {
token := t.nextNonSpace()
if token.typ != expected1 && token.typ != expected2 {
t.unexpected(token, context)
}
return token
}
// unexpected complains about the token and terminates processing.
func (t *Tree) unexpected(token item, context string) {
t.errorf("unexpected %s in %s", token, context)
}
// recover is the handler that turns panics into returns from the top level of Parse.
func (t *Tree) recover(errp *error) {
e := recover()
if e != nil {
if _, ok := e.(runtime.Error); ok {
panic(e)
}
if t != nil {
t.stopParse()
}
*errp = e.(error)
}
return
}
// startParse initializes the parser, using the lexer.
func (t *Tree) startParse(funcs []map[string]interface{}, lex *lexer) {
t.Root = nil
t.lex = lex
t.vars = []string{"$"}
t.funcs = funcs
}
// stopParse terminates parsing.
func (t *Tree) stopParse() {
t.lex = nil
t.vars = nil
t.funcs = nil
}
// Parse parses the template definition string to construct a representation of
// the template for execution. If either action delimiter string is empty, the
// default ("{{" or "}}") is used. Embedded template definitions are added to
// the treeSet map.
func (t *Tree) Parse(text, leftDelim, rightDelim string, treeSet map[string]*Tree, funcs ...map[string]interface{}) (tree *Tree, err error) {
defer t.recover(&err)
t.ParseName = t.Name
t.startParse(funcs, lex(t.Name, text, leftDelim, rightDelim))
t.text = text
t.parse(treeSet)
t.add(treeSet)
t.stopParse()
return t, nil
}
// add adds tree to the treeSet.
func (t *Tree) add(treeSet map[string]*Tree) {
tree := treeSet[t.Name]
if tree == nil || IsEmptyTree(tree.Root) {
treeSet[t.Name] = t
return
}
if !IsEmptyTree(t.Root) {
t.errorf("template: multiple definition of template %q", t.Name)
}
}
// IsEmptyTree reports whether this tree (node) is empty of everything but space.
func IsEmptyTree(n Node) bool {
switch n := n.(type) {
case nil:
return true
case *ActionNode:
case *IfNode:
case *ListNode:
for _, node := range n.Nodes {
if !IsEmptyTree(node) {
return false
}
}
return true
case *RangeNode:
case *TemplateNode:
case *TextNode:
return len(bytes.TrimSpace(n.Text)) == 0
case *WithNode:
default:
panic("unknown node: " + n.String())
}
return false
}
// parse is the top-level parser for a template, essentially the same
// as itemList except it also parses {{define}} actions.
// It runs to EOF.
func (t *Tree) parse(treeSet map[string]*Tree) (next Node) {
t.Root = t.newList(t.peek().pos)
for t.peek().typ != itemEOF {
if t.peek().typ == itemLeftDelim {
delim := t.next()
if t.nextNonSpace().typ == itemDefine {
newT := New("definition") // name will be updated once we know it.
newT.text = t.text
newT.ParseName = t.ParseName
newT.startParse(t.funcs, t.lex)
newT.parseDefinition(treeSet)
continue
}
t.backup2(delim)
}
n := t.textOrAction()
if n.Type() == nodeEnd {
t.errorf("unexpected %s", n)
}
t.Root.append(n)
}
return nil
}
// parseDefinition parses a {{define}} ... {{end}} template definition and
// installs the definition in the treeSet map. The "define" keyword has already
// been scanned.
func (t *Tree) parseDefinition(treeSet map[string]*Tree) {
const context = "define clause"
name := t.expectOneOf(itemString, itemRawString, context)
var err error
t.Name, err = strconv.Unquote(name.val)
if err != nil {
t.error(err)
}
t.expect(itemRightDelim, context)
var end Node
t.Root, end = t.itemList()
if end.Type() != nodeEnd {
t.errorf("unexpected %s in %s", end, context)
}
t.add(treeSet)
t.stopParse()
}
// itemList:
// textOrAction*
// Terminates at {{end}} or {{else}}, returned separately.
func (t *Tree) itemList() (list *ListNode, next Node) {
list = t.newList(t.peekNonSpace().pos)
for t.peekNonSpace().typ != itemEOF {
n := t.textOrAction()
switch n.Type() {
case nodeEnd, nodeElse:
return list, n
}
list.append(n)
}
t.errorf("unexpected EOF")
return
}
// textOrAction:
// text | action
func (t *Tree) textOrAction() Node {
switch token := t.nextNonSpace(); token.typ {
case itemElideNewline:
return t.elideNewline()
case itemText:
return t.newText(token.pos, token.val)
case itemLeftDelim:
return t.action()
default:
t.unexpected(token, "input")
}
return nil
}
// elideNewline:
// Remove newlines trailing rightDelim if \\ is present.
func (t *Tree) elideNewline() Node {
token := t.peek()
if token.typ != itemText {
t.unexpected(token, "input")
return nil
}
t.next()
stripped := strings.TrimLeft(token.val, "\n\r")
diff := len(token.val) - len(stripped)
if diff > 0 {
// This is a bit nasty. We mutate the token in-place to remove
// preceding newlines.
token.pos += Pos(diff)
token.val = stripped
}
return t.newText(token.pos, token.val)
}
// Action:
// control
// command ("|" command)*
// Left delim is past. Now get actions.
// First word could be a keyword such as range.
func (t *Tree) action() (n Node) {
switch token := t.nextNonSpace(); token.typ {
case itemElse:
return t.elseControl()
case itemEnd:
return t.endControl()
case itemIf:
return t.ifControl()
case itemRange:
return t.rangeControl()
case itemTemplate:
return t.templateControl()
case itemWith:
return t.withControl()
}
t.backup()
// Do not pop variables; they persist until "end".
return t.newAction(t.peek().pos, t.lex.lineNumber(), t.pipeline("command"))
}
// Pipeline:
// declarations? command ('|' command)*
func (t *Tree) pipeline(context string) (pipe *PipeNode) {
var decl []*VariableNode
pos := t.peekNonSpace().pos
// Are there declarations?
for {
if v := t.peekNonSpace(); v.typ == itemVariable {
t.next()
// Since space is a token, we need 3-token look-ahead here in the worst case:
// in "$x foo" we need to read "foo" (as opposed to ":=") to know that $x is an
// argument variable rather than a declaration. So remember the token
// adjacent to the variable so we can push it back if necessary.
tokenAfterVariable := t.peek()
if next := t.peekNonSpace(); next.typ == itemColonEquals || (next.typ == itemChar && next.val == ",") {
t.nextNonSpace()
variable := t.newVariable(v.pos, v.val)
decl = append(decl, variable)
t.vars = append(t.vars, v.val)
if next.typ == itemChar && next.val == "," {
if context == "range" && len(decl) < 2 {
continue
}
t.errorf("too many declarations in %s", context)
}
} else if tokenAfterVariable.typ == itemSpace {
t.backup3(v, tokenAfterVariable)
} else {
t.backup2(v)
}
}
break
}
pipe = t.newPipeline(pos, t.lex.lineNumber(), decl)
for {
switch token := t.nextNonSpace(); token.typ {
case itemRightDelim, itemRightParen:
if len(pipe.Cmds) == 0 {
t.errorf("missing value for %s", context)
}
if token.typ == itemRightParen {
t.backup()
}
return
case itemBool, itemCharConstant, itemComplex, itemDot, itemField, itemIdentifier,
itemNumber, itemNil, itemRawString, itemString, itemVariable, itemLeftParen:
t.backup()
pipe.append(t.command())
default:
t.unexpected(token, context)
}
}
}
func (t *Tree) parseControl(allowElseIf bool, context string) (pos Pos, line int, pipe *PipeNode, list, elseList *ListNode) {
defer t.popVars(len(t.vars))
line = t.lex.lineNumber()
pipe = t.pipeline(context)
var next Node
list, next = t.itemList()
switch next.Type() {
case nodeEnd: //done
case nodeElse:
if allowElseIf {
// Special case for "else if". If the "else" is followed immediately by an "if",
// the elseControl will have left the "if" token pending. Treat
// {{if a}}_{{else if b}}_{{end}}
// as
// {{if a}}_{{else}}{{if b}}_{{end}}{{end}}.
// To do this, parse the if as usual and stop at it {{end}}; the subsequent{{end}}
// is assumed. This technique works even for long if-else-if chains.
// TODO: Should we allow else-if in with and range?
if t.peek().typ == itemIf {
t.next() // Consume the "if" token.
elseList = t.newList(next.Position())
elseList.append(t.ifControl())
// Do not consume the next item - only one {{end}} required.
break
}
}
elseList, next = t.itemList()
if next.Type() != nodeEnd {
t.errorf("expected end; found %s", next)
}
}
return pipe.Position(), line, pipe, list, elseList
}
// If:
// {{if pipeline}} itemList {{end}}
// {{if pipeline}} itemList {{else}} itemList {{end}}
// If keyword is past.
func (t *Tree) ifControl() Node {
return t.newIf(t.parseControl(true, "if"))
}
// Range:
// {{range pipeline}} itemList {{end}}
// {{range pipeline}} itemList {{else}} itemList {{end}}
// Range keyword is past.
func (t *Tree) rangeControl() Node {
return t.newRange(t.parseControl(false, "range"))
}
// With:
// {{with pipeline}} itemList {{end}}
// {{with pipeline}} itemList {{else}} itemList {{end}}
// If keyword is past.
func (t *Tree) withControl() Node {
return t.newWith(t.parseControl(false, "with"))
}
// End:
// {{end}}
// End keyword is past.
func (t *Tree) endControl() Node {
return t.newEnd(t.expect(itemRightDelim, "end").pos)
}
// Else:
// {{else}}
// Else keyword is past.
func (t *Tree) elseControl() Node {
// Special case for "else if".
peek := t.peekNonSpace()
if peek.typ == itemIf {
// We see "{{else if ... " but in effect rewrite it to {{else}}{{if ... ".
return t.newElse(peek.pos, t.lex.lineNumber())
}
return t.newElse(t.expect(itemRightDelim, "else").pos, t.lex.lineNumber())
}
// Template:
// {{template stringValue pipeline}}
// Template keyword is past. The name must be something that can evaluate
// to a string.
func (t *Tree) templateControl() Node {
var name string
token := t.nextNonSpace()
switch token.typ {
case itemString, itemRawString:
s, err := strconv.Unquote(token.val)
if err != nil {
t.error(err)
}
name = s
default:
t.unexpected(token, "template invocation")
}
var pipe *PipeNode
if t.nextNonSpace().typ != itemRightDelim {
t.backup()
// Do not pop variables; they persist until "end".
pipe = t.pipeline("template")
}
return t.newTemplate(token.pos, t.lex.lineNumber(), name, pipe)
}
// command:
// operand (space operand)*
// space-separated arguments up to a pipeline character or right delimiter.
// we consume the pipe character but leave the right delim to terminate the action.
func (t *Tree) command() *CommandNode {
cmd := t.newCommand(t.peekNonSpace().pos)
for {
t.peekNonSpace() // skip leading spaces.
operand := t.operand()
if operand != nil {
cmd.append(operand)
}
switch token := t.next(); token.typ {
case itemSpace:
continue
case itemError:
t.errorf("%s", token.val)
case itemRightDelim, itemRightParen:
t.backup()
case itemPipe:
default:
t.errorf("unexpected %s in operand; missing space?", token)
}
break
}
if len(cmd.Args) == 0 {
t.errorf("empty command")
}
return cmd
}
// operand:
// term .Field*
// An operand is a space-separated component of a command,
// a term possibly followed by field accesses.
// A nil return means the next item is not an operand.
func (t *Tree) operand() Node {
node := t.term()
if node == nil {
return nil
}
if t.peek().typ == itemField {
chain := t.newChain(t.peek().pos, node)
for t.peek().typ == itemField {
chain.Add(t.next().val)
}
// Compatibility with original API: If the term is of type NodeField
// or NodeVariable, just put more fields on the original.
// Otherwise, keep the Chain node.
// TODO: Switch to Chains always when we can.
switch node.Type() {
case NodeField:
node = t.newField(chain.Position(), chain.String())
case NodeVariable:
node = t.newVariable(chain.Position(), chain.String())
default:
node = chain
}
}
return node
}
// term:
// literal (number, string, nil, boolean)
// function (identifier)
// .
// .Field
// $
// '(' pipeline ')'
// A term is a simple "expression".
// A nil return means the next item is not a term.
func (t *Tree) term() Node {
switch token := t.nextNonSpace(); token.typ {
case itemError:
t.errorf("%s", token.val)
case itemIdentifier:
if !t.hasFunction(token.val) {
t.errorf("function %q not defined", token.val)
}
return NewIdentifier(token.val).SetTree(t).SetPos(token.pos)
case itemDot:
return t.newDot(token.pos)
case itemNil:
return t.newNil(token.pos)
case itemVariable:
return t.useVar(token.pos, token.val)
case itemField:
return t.newField(token.pos, token.val)
case itemBool:
return t.newBool(token.pos, token.val == "true")
case itemCharConstant, itemComplex, itemNumber:
number, err := t.newNumber(token.pos, token.val, token.typ)
if err != nil {
t.error(err)
}
return number
case itemLeftParen:
pipe := t.pipeline("parenthesized pipeline")
if token := t.next(); token.typ != itemRightParen {
t.errorf("unclosed right paren: unexpected %s", token)
}
return pipe
case itemString, itemRawString:
s, err := strconv.Unquote(token.val)
if err != nil {
t.error(err)
}
return t.newString(token.pos, token.val, s)
}
t.backup()
return nil
}
// hasFunction reports if a function name exists in the Tree's maps.
func (t *Tree) hasFunction(name string) bool {
for _, funcMap := range t.funcs {
if funcMap == nil {
continue
}
if funcMap[name] != nil {
return true
}
}
return false
}
// popVars trims the variable list to the specified length
func (t *Tree) popVars(n int) {
t.vars = t.vars[:n]
}
// useVar returns a node for a variable reference. It errors if the
// variable is not defined.
func (t *Tree) useVar(pos Pos, name string) Node {
v := t.newVariable(pos, name)
for _, varName := range t.vars {
if varName == v.Ident[0] {
return v
}
}
t.errorf("undefined variable %q", v.Ident[0])
return nil
}

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// Copyright 2011 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
package template
import (
"fmt"
"reflect"
"github.com/alecthomas/template/parse"
)
// common holds the information shared by related templates.
type common struct {
tmpl map[string]*Template
// We use two maps, one for parsing and one for execution.
// This separation makes the API cleaner since it doesn't
// expose reflection to the client.
parseFuncs FuncMap
execFuncs map[string]reflect.Value
}
// Template is the representation of a parsed template. The *parse.Tree
// field is exported only for use by html/template and should be treated
// as unexported by all other clients.
type Template struct {
name string
*parse.Tree
*common
leftDelim string
rightDelim string
}
// New allocates a new template with the given name.
func New(name string) *Template {
return &Template{
name: name,
}
}
// Name returns the name of the template.
func (t *Template) Name() string {
return t.name
}
// New allocates a new template associated with the given one and with the same
// delimiters. The association, which is transitive, allows one template to
// invoke another with a {{template}} action.
func (t *Template) New(name string) *Template {
t.init()
return &Template{
name: name,
common: t.common,
leftDelim: t.leftDelim,
rightDelim: t.rightDelim,
}
}
func (t *Template) init() {
if t.common == nil {
t.common = new(common)
t.tmpl = make(map[string]*Template)
t.parseFuncs = make(FuncMap)
t.execFuncs = make(map[string]reflect.Value)
}
}
// Clone returns a duplicate of the template, including all associated
// templates. The actual representation is not copied, but the name space of
// associated templates is, so further calls to Parse in the copy will add
// templates to the copy but not to the original. Clone can be used to prepare
// common templates and use them with variant definitions for other templates
// by adding the variants after the clone is made.
func (t *Template) Clone() (*Template, error) {
nt := t.copy(nil)
nt.init()
nt.tmpl[t.name] = nt
for k, v := range t.tmpl {
if k == t.name { // Already installed.
continue
}
// The associated templates share nt's common structure.
tmpl := v.copy(nt.common)
nt.tmpl[k] = tmpl
}
for k, v := range t.parseFuncs {
nt.parseFuncs[k] = v
}
for k, v := range t.execFuncs {
nt.execFuncs[k] = v
}
return nt, nil
}
// copy returns a shallow copy of t, with common set to the argument.
func (t *Template) copy(c *common) *Template {
nt := New(t.name)
nt.Tree = t.Tree
nt.common = c
nt.leftDelim = t.leftDelim
nt.rightDelim = t.rightDelim
return nt
}
// AddParseTree creates a new template with the name and parse tree
// and associates it with t.
func (t *Template) AddParseTree(name string, tree *parse.Tree) (*Template, error) {
if t.common != nil && t.tmpl[name] != nil {
return nil, fmt.Errorf("template: redefinition of template %q", name)
}
nt := t.New(name)
nt.Tree = tree
t.tmpl[name] = nt
return nt, nil
}
// Templates returns a slice of the templates associated with t, including t
// itself.
func (t *Template) Templates() []*Template {
if t.common == nil {
return nil
}
// Return a slice so we don't expose the map.
m := make([]*Template, 0, len(t.tmpl))
for _, v := range t.tmpl {
m = append(m, v)
}
return m
}
// Delims sets the action delimiters to the specified strings, to be used in
// subsequent calls to Parse, ParseFiles, or ParseGlob. Nested template
// definitions will inherit the settings. An empty delimiter stands for the
// corresponding default: {{ or }}.
// The return value is the template, so calls can be chained.
func (t *Template) Delims(left, right string) *Template {
t.leftDelim = left
t.rightDelim = right
return t
}
// Funcs adds the elements of the argument map to the template's function map.
// It panics if a value in the map is not a function with appropriate return
// type. However, it is legal to overwrite elements of the map. The return
// value is the template, so calls can be chained.
func (t *Template) Funcs(funcMap FuncMap) *Template {
t.init()
addValueFuncs(t.execFuncs, funcMap)
addFuncs(t.parseFuncs, funcMap)
return t
}
// Lookup returns the template with the given name that is associated with t,
// or nil if there is no such template.
func (t *Template) Lookup(name string) *Template {
if t.common == nil {
return nil
}
return t.tmpl[name]
}
// Parse parses a string into a template. Nested template definitions will be
// associated with the top-level template t. Parse may be called multiple times
// to parse definitions of templates to associate with t. It is an error if a
// resulting template is non-empty (contains content other than template
// definitions) and would replace a non-empty template with the same name.
// (In multiple calls to Parse with the same receiver template, only one call
// can contain text other than space, comments, and template definitions.)
func (t *Template) Parse(text string) (*Template, error) {
t.init()
trees, err := parse.Parse(t.name, text, t.leftDelim, t.rightDelim, t.parseFuncs, builtins)
if err != nil {
return nil, err
}
// Add the newly parsed trees, including the one for t, into our common structure.
for name, tree := range trees {
// If the name we parsed is the name of this template, overwrite this template.
// The associate method checks it's not a redefinition.
tmpl := t
if name != t.name {
tmpl = t.New(name)
}
// Even if t == tmpl, we need to install it in the common.tmpl map.
if replace, err := t.associate(tmpl, tree); err != nil {
return nil, err
} else if replace {
tmpl.Tree = tree
}
tmpl.leftDelim = t.leftDelim
tmpl.rightDelim = t.rightDelim
}
return t, nil
}
// associate installs the new template into the group of templates associated
// with t. It is an error to reuse a name except to overwrite an empty
// template. The two are already known to share the common structure.
// The boolean return value reports wither to store this tree as t.Tree.
func (t *Template) associate(new *Template, tree *parse.Tree) (bool, error) {
if new.common != t.common {
panic("internal error: associate not common")
}
name := new.name
if old := t.tmpl[name]; old != nil {
oldIsEmpty := parse.IsEmptyTree(old.Root)
newIsEmpty := parse.IsEmptyTree(tree.Root)
if newIsEmpty {
// Whether old is empty or not, new is empty; no reason to replace old.
return false, nil
}
if !oldIsEmpty {
return false, fmt.Errorf("template: redefinition of template %q", name)
}
}
t.tmpl[name] = new
return true, nil
}