mirror of
https://github.com/strongdm/comply
synced 2024-08-27 09:46:47 +00:00
467 lines
13 KiB
Go
467 lines
13 KiB
Go
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// Package yaml implements YAML support for the Go language.
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//
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// Source code and other details for the project are available at GitHub:
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//
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// https://github.com/go-yaml/yaml
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//
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package yaml
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import (
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"errors"
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"fmt"
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"io"
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"reflect"
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"strings"
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"sync"
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)
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// MapSlice encodes and decodes as a YAML map.
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// The order of keys is preserved when encoding and decoding.
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type MapSlice []MapItem
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// MapItem is an item in a MapSlice.
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type MapItem struct {
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Key, Value interface{}
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}
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// The Unmarshaler interface may be implemented by types to customize their
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// behavior when being unmarshaled from a YAML document. The UnmarshalYAML
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// method receives a function that may be called to unmarshal the original
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// YAML value into a field or variable. It is safe to call the unmarshal
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// function parameter more than once if necessary.
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type Unmarshaler interface {
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UnmarshalYAML(unmarshal func(interface{}) error) error
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}
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// The Marshaler interface may be implemented by types to customize their
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// behavior when being marshaled into a YAML document. The returned value
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// is marshaled in place of the original value implementing Marshaler.
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//
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// If an error is returned by MarshalYAML, the marshaling procedure stops
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// and returns with the provided error.
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type Marshaler interface {
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MarshalYAML() (interface{}, error)
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}
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// Unmarshal decodes the first document found within the in byte slice
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// and assigns decoded values into the out value.
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//
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// Maps and pointers (to a struct, string, int, etc) are accepted as out
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// values. If an internal pointer within a struct is not initialized,
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// the yaml package will initialize it if necessary for unmarshalling
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// the provided data. The out parameter must not be nil.
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//
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// The type of the decoded values should be compatible with the respective
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// values in out. If one or more values cannot be decoded due to a type
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// mismatches, decoding continues partially until the end of the YAML
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// content, and a *yaml.TypeError is returned with details for all
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// missed values.
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//
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// Struct fields are only unmarshalled if they are exported (have an
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// upper case first letter), and are unmarshalled using the field name
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// lowercased as the default key. Custom keys may be defined via the
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// "yaml" name in the field tag: the content preceding the first comma
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// is used as the key, and the following comma-separated options are
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// used to tweak the marshalling process (see Marshal).
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// Conflicting names result in a runtime error.
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//
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// For example:
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//
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// type T struct {
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// F int `yaml:"a,omitempty"`
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// B int
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// }
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// var t T
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// yaml.Unmarshal([]byte("a: 1\nb: 2"), &t)
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//
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// See the documentation of Marshal for the format of tags and a list of
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// supported tag options.
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//
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func Unmarshal(in []byte, out interface{}) (err error) {
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return unmarshal(in, out, false)
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}
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// UnmarshalStrict is like Unmarshal except that any fields that are found
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// in the data that do not have corresponding struct members, or mapping
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// keys that are duplicates, will result in
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// an error.
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func UnmarshalStrict(in []byte, out interface{}) (err error) {
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return unmarshal(in, out, true)
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}
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// A Decorder reads and decodes YAML values from an input stream.
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type Decoder struct {
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strict bool
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parser *parser
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}
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// NewDecoder returns a new decoder that reads from r.
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//
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// The decoder introduces its own buffering and may read
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// data from r beyond the YAML values requested.
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func NewDecoder(r io.Reader) *Decoder {
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return &Decoder{
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parser: newParserFromReader(r),
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}
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}
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// SetStrict sets whether strict decoding behaviour is enabled when
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// decoding items in the data (see UnmarshalStrict). By default, decoding is not strict.
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func (dec *Decoder) SetStrict(strict bool) {
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dec.strict = strict
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}
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// Decode reads the next YAML-encoded value from its input
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// and stores it in the value pointed to by v.
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//
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// See the documentation for Unmarshal for details about the
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// conversion of YAML into a Go value.
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func (dec *Decoder) Decode(v interface{}) (err error) {
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d := newDecoder(dec.strict)
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defer handleErr(&err)
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node := dec.parser.parse()
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if node == nil {
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return io.EOF
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}
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out := reflect.ValueOf(v)
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if out.Kind() == reflect.Ptr && !out.IsNil() {
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out = out.Elem()
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}
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d.unmarshal(node, out)
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if len(d.terrors) > 0 {
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return &TypeError{d.terrors}
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}
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return nil
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}
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func unmarshal(in []byte, out interface{}, strict bool) (err error) {
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defer handleErr(&err)
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d := newDecoder(strict)
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p := newParser(in)
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defer p.destroy()
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node := p.parse()
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if node != nil {
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v := reflect.ValueOf(out)
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if v.Kind() == reflect.Ptr && !v.IsNil() {
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v = v.Elem()
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}
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d.unmarshal(node, v)
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}
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if len(d.terrors) > 0 {
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return &TypeError{d.terrors}
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}
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return nil
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}
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// Marshal serializes the value provided into a YAML document. The structure
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// of the generated document will reflect the structure of the value itself.
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// Maps and pointers (to struct, string, int, etc) are accepted as the in value.
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//
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// Struct fields are only unmarshalled if they are exported (have an upper case
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// first letter), and are unmarshalled using the field name lowercased as the
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// default key. Custom keys may be defined via the "yaml" name in the field
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// tag: the content preceding the first comma is used as the key, and the
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// following comma-separated options are used to tweak the marshalling process.
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// Conflicting names result in a runtime error.
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//
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// The field tag format accepted is:
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//
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// `(...) yaml:"[<key>][,<flag1>[,<flag2>]]" (...)`
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//
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// The following flags are currently supported:
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//
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// omitempty Only include the field if it's not set to the zero
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// value for the type or to empty slices or maps.
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// Zero valued structs will be omitted if all their public
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// fields are zero, unless they implement an IsZero
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// method (see the IsZeroer interface type), in which
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// case the field will be included if that method returns true.
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//
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// flow Marshal using a flow style (useful for structs,
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// sequences and maps).
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//
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// inline Inline the field, which must be a struct or a map,
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// causing all of its fields or keys to be processed as if
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// they were part of the outer struct. For maps, keys must
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// not conflict with the yaml keys of other struct fields.
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//
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// In addition, if the key is "-", the field is ignored.
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//
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// For example:
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//
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// type T struct {
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// F int `yaml:"a,omitempty"`
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// B int
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// }
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// yaml.Marshal(&T{B: 2}) // Returns "b: 2\n"
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// yaml.Marshal(&T{F: 1}} // Returns "a: 1\nb: 0\n"
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//
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func Marshal(in interface{}) (out []byte, err error) {
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defer handleErr(&err)
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e := newEncoder()
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defer e.destroy()
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e.marshalDoc("", reflect.ValueOf(in))
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e.finish()
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out = e.out
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return
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}
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// An Encoder writes YAML values to an output stream.
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type Encoder struct {
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encoder *encoder
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}
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// NewEncoder returns a new encoder that writes to w.
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// The Encoder should be closed after use to flush all data
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// to w.
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func NewEncoder(w io.Writer) *Encoder {
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return &Encoder{
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encoder: newEncoderWithWriter(w),
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}
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}
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// Encode writes the YAML encoding of v to the stream.
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// If multiple items are encoded to the stream, the
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// second and subsequent document will be preceded
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// with a "---" document separator, but the first will not.
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//
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// See the documentation for Marshal for details about the conversion of Go
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// values to YAML.
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func (e *Encoder) Encode(v interface{}) (err error) {
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defer handleErr(&err)
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e.encoder.marshalDoc("", reflect.ValueOf(v))
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return nil
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}
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// Close closes the encoder by writing any remaining data.
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// It does not write a stream terminating string "...".
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func (e *Encoder) Close() (err error) {
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defer handleErr(&err)
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e.encoder.finish()
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return nil
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}
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func handleErr(err *error) {
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if v := recover(); v != nil {
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if e, ok := v.(yamlError); ok {
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*err = e.err
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} else {
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panic(v)
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}
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}
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}
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type yamlError struct {
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err error
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}
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func fail(err error) {
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panic(yamlError{err})
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}
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func failf(format string, args ...interface{}) {
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panic(yamlError{fmt.Errorf("yaml: "+format, args...)})
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}
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// A TypeError is returned by Unmarshal when one or more fields in
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// the YAML document cannot be properly decoded into the requested
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// types. When this error is returned, the value is still
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// unmarshaled partially.
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type TypeError struct {
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Errors []string
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}
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func (e *TypeError) Error() string {
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return fmt.Sprintf("yaml: unmarshal errors:\n %s", strings.Join(e.Errors, "\n "))
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}
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// --------------------------------------------------------------------------
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// Maintain a mapping of keys to structure field indexes
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// The code in this section was copied from mgo/bson.
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// structInfo holds details for the serialization of fields of
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// a given struct.
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type structInfo struct {
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FieldsMap map[string]fieldInfo
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FieldsList []fieldInfo
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// InlineMap is the number of the field in the struct that
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// contains an ,inline map, or -1 if there's none.
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InlineMap int
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}
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type fieldInfo struct {
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Key string
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Num int
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OmitEmpty bool
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Flow bool
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// Id holds the unique field identifier, so we can cheaply
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// check for field duplicates without maintaining an extra map.
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Id int
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// Inline holds the field index if the field is part of an inlined struct.
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Inline []int
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}
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var structMap = make(map[reflect.Type]*structInfo)
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var fieldMapMutex sync.RWMutex
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func getStructInfo(st reflect.Type) (*structInfo, error) {
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fieldMapMutex.RLock()
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sinfo, found := structMap[st]
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fieldMapMutex.RUnlock()
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if found {
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return sinfo, nil
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}
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n := st.NumField()
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fieldsMap := make(map[string]fieldInfo)
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fieldsList := make([]fieldInfo, 0, n)
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inlineMap := -1
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for i := 0; i != n; i++ {
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field := st.Field(i)
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if field.PkgPath != "" && !field.Anonymous {
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continue // Private field
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}
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info := fieldInfo{Num: i}
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tag := field.Tag.Get("yaml")
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if tag == "" && strings.Index(string(field.Tag), ":") < 0 {
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tag = string(field.Tag)
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}
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if tag == "-" {
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continue
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}
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inline := false
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fields := strings.Split(tag, ",")
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if len(fields) > 1 {
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for _, flag := range fields[1:] {
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switch flag {
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case "omitempty":
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info.OmitEmpty = true
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case "flow":
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info.Flow = true
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case "inline":
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inline = true
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default:
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return nil, errors.New(fmt.Sprintf("Unsupported flag %q in tag %q of type %s", flag, tag, st))
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}
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}
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tag = fields[0]
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}
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if inline {
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switch field.Type.Kind() {
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case reflect.Map:
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if inlineMap >= 0 {
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return nil, errors.New("Multiple ,inline maps in struct " + st.String())
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}
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if field.Type.Key() != reflect.TypeOf("") {
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return nil, errors.New("Option ,inline needs a map with string keys in struct " + st.String())
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}
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inlineMap = info.Num
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case reflect.Struct:
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sinfo, err := getStructInfo(field.Type)
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if err != nil {
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return nil, err
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}
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for _, finfo := range sinfo.FieldsList {
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if _, found := fieldsMap[finfo.Key]; found {
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msg := "Duplicated key '" + finfo.Key + "' in struct " + st.String()
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return nil, errors.New(msg)
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}
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if finfo.Inline == nil {
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finfo.Inline = []int{i, finfo.Num}
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} else {
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finfo.Inline = append([]int{i}, finfo.Inline...)
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}
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finfo.Id = len(fieldsList)
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fieldsMap[finfo.Key] = finfo
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fieldsList = append(fieldsList, finfo)
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}
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default:
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//return nil, errors.New("Option ,inline needs a struct value or map field")
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return nil, errors.New("Option ,inline needs a struct value field")
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}
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continue
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}
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if tag != "" {
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info.Key = tag
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} else {
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info.Key = strings.ToLower(field.Name)
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}
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if _, found = fieldsMap[info.Key]; found {
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msg := "Duplicated key '" + info.Key + "' in struct " + st.String()
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return nil, errors.New(msg)
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}
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info.Id = len(fieldsList)
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fieldsList = append(fieldsList, info)
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fieldsMap[info.Key] = info
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}
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sinfo = &structInfo{
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FieldsMap: fieldsMap,
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FieldsList: fieldsList,
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InlineMap: inlineMap,
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}
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fieldMapMutex.Lock()
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structMap[st] = sinfo
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fieldMapMutex.Unlock()
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return sinfo, nil
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}
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// IsZeroer is used to check whether an object is zero to
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// determine whether it should be omitted when marshaling
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// with the omitempty flag. One notable implementation
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// is time.Time.
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type IsZeroer interface {
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IsZero() bool
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}
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func isZero(v reflect.Value) bool {
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kind := v.Kind()
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if z, ok := v.Interface().(IsZeroer); ok {
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if (kind == reflect.Ptr || kind == reflect.Interface) && v.IsNil() {
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return true
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}
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return z.IsZero()
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}
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switch kind {
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case reflect.String:
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return len(v.String()) == 0
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case reflect.Interface, reflect.Ptr:
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return v.IsNil()
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case reflect.Slice:
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return v.Len() == 0
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case reflect.Map:
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return v.Len() == 0
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case reflect.Int, reflect.Int8, reflect.Int16, reflect.Int32, reflect.Int64:
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return v.Int() == 0
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case reflect.Float32, reflect.Float64:
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return v.Float() == 0
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case reflect.Uint, reflect.Uint8, reflect.Uint16, reflect.Uint32, reflect.Uint64, reflect.Uintptr:
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return v.Uint() == 0
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case reflect.Bool:
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||
|
return !v.Bool()
|
||
|
case reflect.Struct:
|
||
|
vt := v.Type()
|
||
|
for i := v.NumField() - 1; i >= 0; i-- {
|
||
|
if vt.Field(i).PkgPath != "" {
|
||
|
continue // Private field
|
||
|
}
|
||
|
if !isZero(v.Field(i)) {
|
||
|
return false
|
||
|
}
|
||
|
}
|
||
|
return true
|
||
|
}
|
||
|
return false
|
||
|
}
|