diff options
Diffstat (limited to 'vendor/gopkg.in/mgo.v2/internal/json/encode.go')
| -rw-r--r-- | vendor/gopkg.in/mgo.v2/internal/json/encode.go | 1256 |
1 files changed, 1256 insertions, 0 deletions
diff --git a/vendor/gopkg.in/mgo.v2/internal/json/encode.go b/vendor/gopkg.in/mgo.v2/internal/json/encode.go new file mode 100644 index 0000000..67a0f00 --- /dev/null +++ b/vendor/gopkg.in/mgo.v2/internal/json/encode.go @@ -0,0 +1,1256 @@ +// Copyright 2010 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 json implements encoding and decoding of JSON as defined in +// RFC 4627. The mapping between JSON and Go values is described +// in the documentation for the Marshal and Unmarshal functions. +// +// See "JSON and Go" for an introduction to this package: +// https://golang.org/doc/articles/json_and_go.html +package json + +import ( + "bytes" + "encoding" + "encoding/base64" + "fmt" + "math" + "reflect" + "runtime" + "sort" + "strconv" + "strings" + "sync" + "unicode" + "unicode/utf8" +) + +// Marshal returns the JSON encoding of v. +// +// Marshal traverses the value v recursively. +// If an encountered value implements the Marshaler interface +// and is not a nil pointer, Marshal calls its MarshalJSON method +// to produce JSON. If no MarshalJSON method is present but the +// value implements encoding.TextMarshaler instead, Marshal calls +// its MarshalText method. +// The nil pointer exception is not strictly necessary +// but mimics a similar, necessary exception in the behavior of +// UnmarshalJSON. +// +// Otherwise, Marshal uses the following type-dependent default encodings: +// +// Boolean values encode as JSON booleans. +// +// Floating point, integer, and Number values encode as JSON numbers. +// +// String values encode as JSON strings coerced to valid UTF-8, +// replacing invalid bytes with the Unicode replacement rune. +// The angle brackets "<" and ">" are escaped to "\u003c" and "\u003e" +// to keep some browsers from misinterpreting JSON output as HTML. +// Ampersand "&" is also escaped to "\u0026" for the same reason. +// This escaping can be disabled using an Encoder with DisableHTMLEscaping. +// +// Array and slice values encode as JSON arrays, except that +// []byte encodes as a base64-encoded string, and a nil slice +// encodes as the null JSON value. +// +// Struct values encode as JSON objects. Each exported struct field +// becomes a member of the object unless +// - the field's tag is "-", or +// - the field is empty and its tag specifies the "omitempty" option. +// The empty values are false, 0, any +// nil pointer or interface value, and any array, slice, map, or string of +// length zero. The object's default key string is the struct field name +// but can be specified in the struct field's tag value. The "json" key in +// the struct field's tag value is the key name, followed by an optional comma +// and options. Examples: +// +// // Field is ignored by this package. +// Field int `json:"-"` +// +// // Field appears in JSON as key "myName". +// Field int `json:"myName"` +// +// // Field appears in JSON as key "myName" and +// // the field is omitted from the object if its value is empty, +// // as defined above. +// Field int `json:"myName,omitempty"` +// +// // Field appears in JSON as key "Field" (the default), but +// // the field is skipped if empty. +// // Note the leading comma. +// Field int `json:",omitempty"` +// +// The "string" option signals that a field is stored as JSON inside a +// JSON-encoded string. It applies only to fields of string, floating point, +// integer, or boolean types. This extra level of encoding is sometimes used +// when communicating with JavaScript programs: +// +// Int64String int64 `json:",string"` +// +// The key name will be used if it's a non-empty string consisting of +// only Unicode letters, digits, dollar signs, percent signs, hyphens, +// underscores and slashes. +// +// Anonymous struct fields are usually marshaled as if their inner exported fields +// were fields in the outer struct, subject to the usual Go visibility rules amended +// as described in the next paragraph. +// An anonymous struct field with a name given in its JSON tag is treated as +// having that name, rather than being anonymous. +// An anonymous struct field of interface type is treated the same as having +// that type as its name, rather than being anonymous. +// +// The Go visibility rules for struct fields are amended for JSON when +// deciding which field to marshal or unmarshal. If there are +// multiple fields at the same level, and that level is the least +// nested (and would therefore be the nesting level selected by the +// usual Go rules), the following extra rules apply: +// +// 1) Of those fields, if any are JSON-tagged, only tagged fields are considered, +// even if there are multiple untagged fields that would otherwise conflict. +// 2) If there is exactly one field (tagged or not according to the first rule), that is selected. +// 3) Otherwise there are multiple fields, and all are ignored; no error occurs. +// +// Handling of anonymous struct fields is new in Go 1.1. +// Prior to Go 1.1, anonymous struct fields were ignored. To force ignoring of +// an anonymous struct field in both current and earlier versions, give the field +// a JSON tag of "-". +// +// Map values encode as JSON objects. The map's key type must either be a string +// or implement encoding.TextMarshaler. The map keys are used as JSON object +// keys, subject to the UTF-8 coercion described for string values above. +// +// Pointer values encode as the value pointed to. +// A nil pointer encodes as the null JSON value. +// +// Interface values encode as the value contained in the interface. +// A nil interface value encodes as the null JSON value. +// +// Channel, complex, and function values cannot be encoded in JSON. +// Attempting to encode such a value causes Marshal to return +// an UnsupportedTypeError. +// +// JSON cannot represent cyclic data structures and Marshal does not +// handle them. Passing cyclic structures to Marshal will result in +// an infinite recursion. +// +func Marshal(v interface{}) ([]byte, error) { + e := &encodeState{} + err := e.marshal(v, encOpts{escapeHTML: true}) + if err != nil { + return nil, err + } + return e.Bytes(), nil +} + +// MarshalIndent is like Marshal but applies Indent to format the output. +func MarshalIndent(v interface{}, prefix, indent string) ([]byte, error) { + b, err := Marshal(v) + if err != nil { + return nil, err + } + var buf bytes.Buffer + err = Indent(&buf, b, prefix, indent) + if err != nil { + return nil, err + } + return buf.Bytes(), nil +} + +// HTMLEscape appends to dst the JSON-encoded src with <, >, &, U+2028 and U+2029 +// characters inside string literals changed to \u003c, \u003e, \u0026, \u2028, \u2029 +// so that the JSON will be safe to embed inside HTML <script> tags. +// For historical reasons, web browsers don't honor standard HTML +// escaping within <script> tags, so an alternative JSON encoding must +// be used. +func HTMLEscape(dst *bytes.Buffer, src []byte) { + // The characters can only appear in string literals, + // so just scan the string one byte at a time. + start := 0 + for i, c := range src { + if c == '<' || c == '>' || c == '&' { + if start < i { + dst.Write(src[start:i]) + } + dst.WriteString(`\u00`) + dst.WriteByte(hex[c>>4]) + dst.WriteByte(hex[c&0xF]) + start = i + 1 + } + // Convert U+2028 and U+2029 (E2 80 A8 and E2 80 A9). + if c == 0xE2 && i+2 < len(src) && src[i+1] == 0x80 && src[i+2]&^1 == 0xA8 { + if start < i { + dst.Write(src[start:i]) + } + dst.WriteString(`\u202`) + dst.WriteByte(hex[src[i+2]&0xF]) + start = i + 3 + } + } + if start < len(src) { + dst.Write(src[start:]) + } +} + +// Marshaler is the interface implemented by types that +// can marshal themselves into valid JSON. +type Marshaler interface { + MarshalJSON() ([]byte, error) +} + +// An UnsupportedTypeError is returned by Marshal when attempting +// to encode an unsupported value type. +type UnsupportedTypeError struct { + Type reflect.Type +} + +func (e *UnsupportedTypeError) Error() string { + return "json: unsupported type: " + e.Type.String() +} + +type UnsupportedValueError struct { + Value reflect.Value + Str string +} + +func (e *UnsupportedValueError) Error() string { + return "json: unsupported value: " + e.Str +} + +// Before Go 1.2, an InvalidUTF8Error was returned by Marshal when +// attempting to encode a string value with invalid UTF-8 sequences. +// As of Go 1.2, Marshal instead coerces the string to valid UTF-8 by +// replacing invalid bytes with the Unicode replacement rune U+FFFD. +// This error is no longer generated but is kept for backwards compatibility +// with programs that might mention it. +type InvalidUTF8Error struct { + S string // the whole string value that caused the error +} + +func (e *InvalidUTF8Error) Error() string { + return "json: invalid UTF-8 in string: " + strconv.Quote(e.S) +} + +type MarshalerError struct { + Type reflect.Type + Err error +} + +func (e *MarshalerError) Error() string { + return "json: error calling MarshalJSON for type " + e.Type.String() + ": " + e.Err.Error() +} + +var hex = "0123456789abcdef" + +// An encodeState encodes JSON into a bytes.Buffer. +type encodeState struct { + bytes.Buffer // accumulated output + scratch [64]byte + ext Extension +} + +var encodeStatePool sync.Pool + +func newEncodeState() *encodeState { + if v := encodeStatePool.Get(); v != nil { + e := v.(*encodeState) + e.Reset() + return e + } + return new(encodeState) +} + +func (e *encodeState) marshal(v interface{}, opts encOpts) (err error) { + defer func() { + if r := recover(); r != nil { + if _, ok := r.(runtime.Error); ok { + panic(r) + } + if s, ok := r.(string); ok { + panic(s) + } + err = r.(error) + } + }() + e.reflectValue(reflect.ValueOf(v), opts) + return nil +} + +func (e *encodeState) error(err error) { + panic(err) +} + +func isEmptyValue(v reflect.Value) bool { + switch v.Kind() { + case reflect.Array, reflect.Map, reflect.Slice, reflect.String: + return v.Len() == 0 + case reflect.Bool: + return !v.Bool() + case reflect.Int, reflect.Int8, reflect.Int16, reflect.Int32, reflect.Int64: + return v.Int() == 0 + case reflect.Uint, reflect.Uint8, reflect.Uint16, reflect.Uint32, reflect.Uint64, reflect.Uintptr: + return v.Uint() == 0 + case reflect.Float32, reflect.Float64: + return v.Float() == 0 + case reflect.Interface, reflect.Ptr: + return v.IsNil() + } + return false +} + +func (e *encodeState) reflectValue(v reflect.Value, opts encOpts) { + valueEncoder(v)(e, v, opts) +} + +type encOpts struct { + // quoted causes primitive fields to be encoded inside JSON strings. + quoted bool + // escapeHTML causes '<', '>', and '&' to be escaped in JSON strings. + escapeHTML bool +} + +type encoderFunc func(e *encodeState, v reflect.Value, opts encOpts) + +var encoderCache struct { + sync.RWMutex + m map[reflect.Type]encoderFunc +} + +func valueEncoder(v reflect.Value) encoderFunc { + if !v.IsValid() { + return invalidValueEncoder + } + return typeEncoder(v.Type()) +} + +func typeEncoder(t reflect.Type) encoderFunc { + encoderCache.RLock() + f := encoderCache.m[t] + encoderCache.RUnlock() + if f != nil { + return f + } + + // To deal with recursive types, populate the map with an + // indirect func before we build it. This type waits on the + // real func (f) to be ready and then calls it. This indirect + // func is only used for recursive types. + encoderCache.Lock() + if encoderCache.m == nil { + encoderCache.m = make(map[reflect.Type]encoderFunc) + } + var wg sync.WaitGroup + wg.Add(1) + encoderCache.m[t] = func(e *encodeState, v reflect.Value, opts encOpts) { + wg.Wait() + f(e, v, opts) + } + encoderCache.Unlock() + + // Compute fields without lock. + // Might duplicate effort but won't hold other computations back. + innerf := newTypeEncoder(t, true) + f = func(e *encodeState, v reflect.Value, opts encOpts) { + encode, ok := e.ext.encode[v.Type()] + if !ok { + innerf(e, v, opts) + return + } + + b, err := encode(v.Interface()) + if err == nil { + // copy JSON into buffer, checking validity. + err = compact(&e.Buffer, b, opts.escapeHTML) + } + if err != nil { + e.error(&MarshalerError{v.Type(), err}) + } + } + wg.Done() + encoderCache.Lock() + encoderCache.m[t] = f + encoderCache.Unlock() + return f +} + +var ( + marshalerType = reflect.TypeOf(new(Marshaler)).Elem() + textMarshalerType = reflect.TypeOf(new(encoding.TextMarshaler)).Elem() +) + +// newTypeEncoder constructs an encoderFunc for a type. +// The returned encoder only checks CanAddr when allowAddr is true. +func newTypeEncoder(t reflect.Type, allowAddr bool) encoderFunc { + if t.Implements(marshalerType) { + return marshalerEncoder + } + if t.Kind() != reflect.Ptr && allowAddr { + if reflect.PtrTo(t).Implements(marshalerType) { + return newCondAddrEncoder(addrMarshalerEncoder, newTypeEncoder(t, false)) + } + } + + if t.Implements(textMarshalerType) { + return textMarshalerEncoder + } + if t.Kind() != reflect.Ptr && allowAddr { + if reflect.PtrTo(t).Implements(textMarshalerType) { + return newCondAddrEncoder(addrTextMarshalerEncoder, newTypeEncoder(t, false)) + } + } + + switch t.Kind() { + case reflect.Bool: + return boolEncoder + case reflect.Int, reflect.Int8, reflect.Int16, reflect.Int32, reflect.Int64: + return intEncoder + case reflect.Uint, reflect.Uint8, reflect.Uint16, reflect.Uint32, reflect.Uint64, reflect.Uintptr: + return uintEncoder + case reflect.Float32: + return float32Encoder + case reflect.Float64: + return float64Encoder + case reflect.String: + return stringEncoder + case reflect.Interface: + return interfaceEncoder + case reflect.Struct: + return newStructEncoder(t) + case reflect.Map: + return newMapEncoder(t) + case reflect.Slice: + return newSliceEncoder(t) + case reflect.Array: + return newArrayEncoder(t) + case reflect.Ptr: + return newPtrEncoder(t) + default: + return unsupportedTypeEncoder + } +} + +func invalidValueEncoder(e *encodeState, v reflect.Value, _ encOpts) { + e.WriteString("null") +} + +func marshalerEncoder(e *encodeState, v reflect.Value, opts encOpts) { + if v.Kind() == reflect.Ptr && v.IsNil() { + e.WriteString("null") + return + } + m := v.Interface().(Marshaler) + b, err := m.MarshalJSON() + if err == nil { + // copy JSON into buffer, checking validity. + err = compact(&e.Buffer, b, opts.escapeHTML) + } + if err != nil { + e.error(&MarshalerError{v.Type(), err}) + } +} + +func addrMarshalerEncoder(e *encodeState, v reflect.Value, _ encOpts) { + va := v.Addr() + if va.IsNil() { + e.WriteString("null") + return + } + m := va.Interface().(Marshaler) + b, err := m.MarshalJSON() + if err == nil { + // copy JSON into buffer, checking validity. + err = compact(&e.Buffer, b, true) + } + if err != nil { + e.error(&MarshalerError{v.Type(), err}) + } +} + +func textMarshalerEncoder(e *encodeState, v reflect.Value, opts encOpts) { + if v.Kind() == reflect.Ptr && v.IsNil() { + e.WriteString("null") + return + } + m := v.Interface().(encoding.TextMarshaler) + b, err := m.MarshalText() + if err != nil { + e.error(&MarshalerError{v.Type(), err}) + } + e.stringBytes(b, opts.escapeHTML) +} + +func addrTextMarshalerEncoder(e *encodeState, v reflect.Value, opts encOpts) { + va := v.Addr() + if va.IsNil() { + e.WriteString("null") + return + } + m := va.Interface().(encoding.TextMarshaler) + b, err := m.MarshalText() + if err != nil { + e.error(&MarshalerError{v.Type(), err}) + } + e.stringBytes(b, opts.escapeHTML) +} + +func boolEncoder(e *encodeState, v reflect.Value, opts encOpts) { + if opts.quoted { + e.WriteByte('"') + } + if v.Bool() { + e.WriteString("true") + } else { + e.WriteString("false") + } + if opts.quoted { + e.WriteByte('"') + } +} + +func intEncoder(e *encodeState, v reflect.Value, opts encOpts) { + b := strconv.AppendInt(e.scratch[:0], v.Int(), 10) + if opts.quoted { + e.WriteByte('"') + } + e.Write(b) + if opts.quoted { + e.WriteByte('"') + } +} + +func uintEncoder(e *encodeState, v reflect.Value, opts encOpts) { + b := strconv.AppendUint(e.scratch[:0], v.Uint(), 10) + if opts.quoted { + e.WriteByte('"') + } + e.Write(b) + if opts.quoted { + e.WriteByte('"') + } +} + +type floatEncoder int // number of bits + +func (bits floatEncoder) encode(e *encodeState, v reflect.Value, opts encOpts) { + f := v.Float() + if math.IsInf(f, 0) || math.IsNaN(f) { + e.error(&UnsupportedValueError{v, strconv.FormatFloat(f, 'g', -1, int(bits))}) + } + b := strconv.AppendFloat(e.scratch[:0], f, 'g', -1, int(bits)) + if opts.quoted { + e.WriteByte('"') + } + e.Write(b) + if opts.quoted { + e.WriteByte('"') + } +} + +var ( + float32Encoder = (floatEncoder(32)).encode + float64Encoder = (floatEncoder(64)).encode +) + +func stringEncoder(e *encodeState, v reflect.Value, opts encOpts) { + if v.Type() == numberType { + numStr := v.String() + // In Go1.5 the empty string encodes to "0", while this is not a valid number literal + // we keep compatibility so check validity after this. + if numStr == "" { + numStr = "0" // Number's zero-val + } + if !isValidNumber(numStr) { + e.error(fmt.Errorf("json: invalid number literal %q", numStr)) + } + e.WriteString(numStr) + return + } + if opts.quoted { + sb, err := Marshal(v.String()) + if err != nil { + e.error(err) + } + e.string(string(sb), opts.escapeHTML) + } else { + e.string(v.String(), opts.escapeHTML) + } +} + +func interfaceEncoder(e *encodeState, v reflect.Value, opts encOpts) { + if v.IsNil() { + e.WriteString("null") + return + } + e.reflectValue(v.Elem(), opts) +} + +func unsupportedTypeEncoder(e *encodeState, v reflect.Value, _ encOpts) { + e.error(&UnsupportedTypeError{v.Type()}) +} + +type structEncoder struct { + fields []field + fieldEncs []encoderFunc +} + +func (se *structEncoder) encode(e *encodeState, v reflect.Value, opts encOpts) { + e.WriteByte('{') + first := true + for i, f := range se.fields { + fv := fieldByIndex(v, f.index) + if !fv.IsValid() || f.omitEmpty && isEmptyValue(fv) { + continue + } + if first { + first = false + } else { + e.WriteByte(',') + } + e.string(f.name, opts.escapeHTML) + e.WriteByte(':') + opts.quoted = f.quoted + se.fieldEncs[i](e, fv, opts) + } + e.WriteByte('}') +} + +func newStructEncoder(t reflect.Type) encoderFunc { + fields := cachedTypeFields(t) + se := &structEncoder{ + fields: fields, + fieldEncs: make([]encoderFunc, len(fields)), + } + for i, f := range fields { + se.fieldEncs[i] = typeEncoder(typeByIndex(t, f.index)) + } + return se.encode +} + +type mapEncoder struct { + elemEnc encoderFunc +} + +func (me *mapEncoder) encode(e *encodeState, v reflect.Value, opts encOpts) { + if v.IsNil() { + e.WriteString("null") + return + } + e.WriteByte('{') + + // Extract and sort the keys. + keys := v.MapKeys() + sv := make([]reflectWithString, len(keys)) + for i, v := range keys { + sv[i].v = v + if err := sv[i].resolve(); err != nil { + e.error(&MarshalerError{v.Type(), err}) + } + } + sort.Sort(byString(sv)) + + for i, kv := range sv { + if i > 0 { + e.WriteByte(',') + } + e.string(kv.s, opts.escapeHTML) + e.WriteByte(':') + me.elemEnc(e, v.MapIndex(kv.v), opts) + } + e.WriteByte('}') +} + +func newMapEncoder(t reflect.Type) encoderFunc { + if t.Key().Kind() != reflect.String && !t.Key().Implements(textMarshalerType) { + return unsupportedTypeEncoder + } + me := &mapEncoder{typeEncoder(t.Elem())} + return me.encode +} + +func encodeByteSlice(e *encodeState, v reflect.Value, _ encOpts) { + if v.IsNil() { + e.WriteString("null") + return + } + s := v.Bytes() + e.WriteByte('"') + if len(s) < 1024 { + // for small buffers, using Encode directly is much faster. + dst := make([]byte, base64.StdEncoding.EncodedLen(len(s))) + base64.StdEncoding.Encode(dst, s) + e.Write(dst) + } else { + // for large buffers, avoid unnecessary extra temporary + // buffer space. + enc := base64.NewEncoder(base64.StdEncoding, e) + enc.Write(s) + enc.Close() + } + e.WriteByte('"') +} + +// sliceEncoder just wraps an arrayEncoder, checking to make sure the value isn't nil. +type sliceEncoder struct { + arrayEnc encoderFunc +} + +func (se *sliceEncoder) encode(e *encodeState, v reflect.Value, opts encOpts) { + if v.IsNil() { + e.WriteString("null") + return + } + se.arrayEnc(e, v, opts) +} + +func newSliceEncoder(t reflect.Type) encoderFunc { + // Byte slices get special treatment; arrays don't. + if t.Elem().Kind() == reflect.Uint8 && + !t.Elem().Implements(marshalerType) && + !t.Elem().Implements(textMarshalerType) { + return encodeByteSlice + } + enc := &sliceEncoder{newArrayEncoder(t)} + return enc.encode +} + +type arrayEncoder struct { + elemEnc encoderFunc +} + +func (ae *arrayEncoder) encode(e *encodeState, v reflect.Value, opts encOpts) { + e.WriteByte('[') + n := v.Len() + for i := 0; i < n; i++ { + if i > 0 { + e.WriteByte(',') + } + ae.elemEnc(e, v.Index(i), opts) + } + e.WriteByte(']') +} + +func newArrayEncoder(t reflect.Type) encoderFunc { + enc := &arrayEncoder{typeEncoder(t.Elem())} + return enc.encode +} + +type ptrEncoder struct { + elemEnc encoderFunc +} + +func (pe *ptrEncoder) encode(e *encodeState, v reflect.Value, opts encOpts) { + if v.IsNil() { + e.WriteString("null") + return + } + pe.elemEnc(e, v.Elem(), opts) +} + +func newPtrEncoder(t reflect.Type) encoderFunc { + enc := &ptrEncoder{typeEncoder(t.Elem())} + return enc.encode +} + +type condAddrEncoder struct { + canAddrEnc, elseEnc encoderFunc +} + +func (ce *condAddrEncoder) encode(e *encodeState, v reflect.Value, opts encOpts) { + if v.CanAddr() { + ce.canAddrEnc(e, v, opts) + } else { + ce.elseEnc(e, v, opts) + } +} + +// newCondAddrEncoder returns an encoder that checks whether its value +// CanAddr and delegates to canAddrEnc if so, else to elseEnc. +func newCondAddrEncoder(canAddrEnc, elseEnc encoderFunc) encoderFunc { + enc := &condAddrEncoder{canAddrEnc: canAddrEnc, elseEnc: elseEnc} + return enc.encode +} + +func isValidTag(s string) bool { + if s == "" { + return false + } + for _, c := range s { + switch { + case strings.ContainsRune("!#$%&()*+-./:<=>?@[]^_{|}~ ", c): + // Backslash and quote chars are reserved, but + // otherwise any punctuation chars are allowed + // in a tag name. + default: + if !unicode.IsLetter(c) && !unicode.IsDigit(c) { + return false + } + } + } + return true +} + +func fieldByIndex(v reflect.Value, index []int) reflect.Value { + for _, i := range index { + if v.Kind() == reflect.Ptr { + if v.IsNil() { + return reflect.Value{} + } + v = v.Elem() + } + v = v.Field(i) + } + return v +} + +func typeByIndex(t reflect.Type, index []int) reflect.Type { + for _, i := range index { + if t.Kind() == reflect.Ptr { + t = t.Elem() + } + t = t.Field(i).Type + } + return t +} + +type reflectWithString struct { + v reflect.Value + s string +} + +func (w *reflectWithString) resolve() error { + if w.v.Kind() == reflect.String { + w.s = w.v.String() + return nil + } + buf, err := w.v.Interface().(encoding.TextMarshaler).MarshalText() + w.s = string(buf) + return err +} + +// byString is a slice of reflectWithString where the reflect.Value is either +// a string or an encoding.TextMarshaler. +// It implements the methods to sort by string. +type byString []reflectWithString + +func (sv byString) Len() int { return len(sv) } +func (sv byString) Swap(i, j int) { sv[i], sv[j] = sv[j], sv[i] } +func (sv byString) Less(i, j int) bool { return sv[i].s < sv[j].s } + +// NOTE: keep in sync with stringBytes below. +func (e *encodeState) string(s string, escapeHTML bool) int { + len0 := e.Len() + e.WriteByte('"') + start := 0 + for i := 0; i < len(s); { + if b := s[i]; b < utf8.RuneSelf { + if 0x20 <= b && b != '\\' && b != '"' && + (!escapeHTML || b != '<' && b != '>' && b != '&') { + i++ + continue + } + if start < i { + e.WriteString(s[start:i]) + } + switch b { + case '\\', '"': + e.WriteByte('\\') + e.WriteByte(b) + case '\n': + e.WriteByte('\\') + e.WriteByte('n') + case '\r': + e.WriteByte('\\') + e.WriteByte('r') + case '\t': + e.WriteByte('\\') + e.WriteByte('t') + default: + // This encodes bytes < 0x20 except for \t, \n and \r. + // If escapeHTML is set, it also escapes <, >, and & + // because they can lead to security holes when + // user-controlled strings are rendered into JSON + // and served to some browsers. + e.WriteString(`\u00`) + e.WriteByte(hex[b>>4]) + e.WriteByte(hex[b&0xF]) + } + i++ + start = i + continue + } + c, size := utf8.DecodeRuneInString(s[i:]) + if c == utf8.RuneError && size == 1 { + if start < i { + e.WriteString(s[start:i]) + } + e.WriteString(`\ufffd`) + i += size + start = i + continue + } + // U+2028 is LINE SEPARATOR. + // U+2029 is PARAGRAPH SEPARATOR. + // They are both technically valid characters in JSON strings, + // but don't work in JSONP, which has to be evaluated as JavaScript, + // and can lead to security holes there. It is valid JSON to + // escape them, so we do so unconditionally. + // See http://timelessrepo.com/json-isnt-a-javascript-subset for discussion. + if c == '\u2028' || c == '\u2029' { + if start < i { + e.WriteString(s[start:i]) + } + e.WriteString(`\u202`) + e.WriteByte(hex[c&0xF]) + i += size + start = i + continue + } + i += size + } + if start < len(s) { + e.WriteString(s[start:]) + } + e.WriteByte('"') + return e.Len() - len0 +} + +// NOTE: keep in sync with string above. +func (e *encodeState) stringBytes(s []byte, escapeHTML bool) int { + len0 := e.Len() + e.WriteByte('"') + start := 0 + for i := 0; i < len(s); { + if b := s[i]; b < utf8.RuneSelf { + if 0x20 <= b && b != '\\' && b != '"' && + (!escapeHTML || b != '<' && b != '>' && b != '&') { + i++ + continue + } + if start < i { + e.Write(s[start:i]) + } + switch b { + case '\\', '"': + e.WriteByte('\\') + e.WriteByte(b) + case '\n': + e.WriteByte('\\') + e.WriteByte('n') + case '\r': + e.WriteByte('\\') + e.WriteByte('r') + case '\t': + e.WriteByte('\\') + e.WriteByte('t') + default: + // This encodes bytes < 0x20 except for \t, \n and \r. + // If escapeHTML is set, it also escapes <, >, and & + // because they can lead to security holes when + // user-controlled strings are rendered into JSON + // and served to some browsers. + e.WriteString(`\u00`) + e.WriteByte(hex[b>>4]) + e.WriteByte(hex[b&0xF]) + } + i++ + start = i + continue + } + c, size := utf8.DecodeRune(s[i:]) + if c == utf8.RuneError && size == 1 { + if start < i { + e.Write(s[start:i]) + } + e.WriteString(`\ufffd`) + i += size + start = i + continue + } + // U+2028 is LINE SEPARATOR. + // U+2029 is PARAGRAPH SEPARATOR. + // They are both technically valid characters in JSON strings, + // but don't work in JSONP, which has to be evaluated as JavaScript, + // and can lead to security holes there. It is valid JSON to + // escape them, so we do so unconditionally. + // See http://timelessrepo.com/json-isnt-a-javascript-subset for discussion. + if c == '\u2028' || c == '\u2029' { + if start < i { + e.Write(s[start:i]) + } + e.WriteString(`\u202`) + e.WriteByte(hex[c&0xF]) + i += size + start = i + continue + } + i += size + } + if start < len(s) { + e.Write(s[start:]) + } + e.WriteByte('"') + return e.Len() - len0 +} + +// A field represents a single field found in a struct. +type field struct { + name string + nameBytes []byte // []byte(name) + equalFold func(s, t []byte) bool // bytes.EqualFold or equivalent + + tag bool + index []int + typ reflect.Type + omitEmpty bool + quoted bool +} + +func fillField(f field) field { + f.nameBytes = []byte(f.name) + f.equalFold = foldFunc(f.nameBytes) + return f +} + +// byName sorts field by name, breaking ties with depth, +// then breaking ties with "name came from json tag", then +// breaking ties with index sequence. +type byName []field + +func (x byName) Len() int { return len(x) } + +func (x byName) Swap(i, j int) { x[i], x[j] = x[j], x[i] } + +func (x byName) Less(i, j int) bool { + if x[i].name != x[j].name { + return x[i].name < x[j].name + } + if len(x[i].index) != len(x[j].index) { + return len(x[i].index) < len(x[j].index) + } + if x[i].tag != x[j].tag { + return x[i].tag + } + return byIndex(x).Less(i, j) +} + +// byIndex sorts field by index sequence. +type byIndex []field + +func (x byIndex) Len() int { return len(x) } + +func (x byIndex) Swap(i, j int) { x[i], x[j] = x[j], x[i] } + +func (x byIndex) Less(i, j int) bool { + for k, xik := range x[i].index { + if k >= len(x[j].index) { + return false + } + if xik != x[j].index[k] { + return xik < x[j].index[k] + } + } + return len(x[i].index) < len(x[j].index) +} + +// typeFields returns a list of fields that JSON should recognize for the given type. +// The algorithm is breadth-first search over the set of structs to include - the top struct +// and then any reachable anonymous structs. +func typeFields(t reflect.Type) []field { + // Anonymous fields to explore at the current level and the next. + current := []field{} + next := []field{{typ: t}} + + // Count of queued names for current level and the next. + count := map[reflect.Type]int{} + nextCount := map[reflect.Type]int{} + + // Types already visited at an earlier level. + visited := map[reflect.Type]bool{} + + // Fields found. + var fields []field + + for len(next) > 0 { + current, next = next, current[:0] + count, nextCount = nextCount, map[reflect.Type]int{} + + for _, f := range current { + if visited[f.typ] { + continue + } + visited[f.typ] = true + + // Scan f.typ for fields to include. + for i := 0; i < f.typ.NumField(); i++ { + sf := f.typ.Field(i) + if sf.PkgPath != "" && !sf.Anonymous { // unexported + continue + } + tag := sf.Tag.Get("json") + if tag == "-" { + continue + } + name, opts := parseTag(tag) + if !isValidTag(name) { + name = "" + } + index := make([]int, len(f.index)+1) + copy(index, f.index) + index[len(f.index)] = i + + ft := sf.Type + if ft.Name() == "" && ft.Kind() == reflect.Ptr { + // Follow pointer. + ft = ft.Elem() + } + + // Only strings, floats, integers, and booleans can be quoted. + quoted := false + if opts.Contains("string") { + switch ft.Kind() { + case reflect.Bool, + reflect.Int, reflect.Int8, reflect.Int16, reflect.Int32, reflect.Int64, + reflect.Uint, reflect.Uint8, reflect.Uint16, reflect.Uint32, reflect.Uint64, + reflect.Float32, reflect.Float64, + reflect.String: + quoted = true + } + } + + // Record found field and index sequence. + if name != "" || !sf.Anonymous || ft.Kind() != reflect.Struct { + tagged := name != "" + if name == "" { + name = sf.Name + } + fields = append(fields, fillField(field{ + name: name, + tag: tagged, + index: index, + typ: ft, + omitEmpty: opts.Contains("omitempty"), + quoted: quoted, + })) + if count[f.typ] > 1 { + // If there were multiple instances, add a second, + // so that the annihilation code will see a duplicate. + // It only cares about the distinction between 1 or 2, + // so don't bother generating any more copies. + fields = append(fields, fields[len(fields)-1]) + } + continue + } + + // Record new anonymous struct to explore in next round. + nextCount[ft]++ + if nextCount[ft] == 1 { + next = append(next, fillField(field{name: ft.Name(), index: index, typ: ft})) + } + } + } + } + + sort.Sort(byName(fields)) + + // Delete all fields that are hidden by the Go rules for embedded fields, + // except that fields with JSON tags are promoted. + + // The fields are sorted in primary order of name, secondary order + // of field index length. Loop over names; for each name, delete + // hidden fields by choosing the one dominant field that survives. + out := fields[:0] + for advance, i := 0, 0; i < len(fields); i += advance { + // One iteration per name. + // Find the sequence of fields with the name of this first field. + fi := fields[i] + name := fi.name + for advance = 1; i+advance < len(fields); advance++ { + fj := fields[i+advance] + if fj.name != name { + break + } + } + if advance == 1 { // Only one field with this name + out = append(out, fi) + continue + } + dominant, ok := dominantField(fields[i : i+advance]) + if ok { + out = append(out, dominant) + } + } + + fields = out + sort.Sort(byIndex(fields)) + + return fields +} + +// dominantField looks through the fields, all of which are known to +// have the same name, to find the single field that dominates the +// others using Go's embedding rules, modified by the presence of +// JSON tags. If there are multiple top-level fields, the boolean +// will be false: This condition is an error in Go and we skip all +// the fields. +func dominantField(fields []field) (field, bool) { + // The fields are sorted in increasing index-length order. The winner + // must therefore be one with the shortest index length. Drop all + // longer entries, which is easy: just truncate the slice. + length := len(fields[0].index) + tagged := -1 // Index of first tagged field. + for i, f := range fields { + if len(f.index) > length { + fields = fields[:i] + break + } + if f.tag { + if tagged >= 0 { + // Multiple tagged fields at the same level: conflict. + // Return no field. + return field{}, false + } + tagged = i + } + } + if tagged >= 0 { + return fields[tagged], true + } + // All remaining fields have the same length. If there's more than one, + // we have a conflict (two fields named "X" at the same level) and we + // return no field. + if len(fields) > 1 { + return field{}, false + } + return fields[0], true +} + +var fieldCache struct { + sync.RWMutex + m map[reflect.Type][]field +} + +// cachedTypeFields is like typeFields but uses a cache to avoid repeated work. +func cachedTypeFields(t reflect.Type) []field { + fieldCache.RLock() + f := fieldCache.m[t] + fieldCache.RUnlock() + if f != nil { + return f + } + + // Compute fields without lock. + // Might duplicate effort but won't hold other computations back. + f = typeFields(t) + if f == nil { + f = []field{} + } + + fieldCache.Lock() + if fieldCache.m == nil { + fieldCache.m = map[reflect.Type][]field{} + } + fieldCache.m[t] = f + fieldCache.Unlock() + return f +} |