From 554fd8c5195424bdbcabf5de30fdc183aba391bd Mon Sep 17 00:00:00 2001 From: upstream source tree Date: Sun, 15 Mar 2015 20:14:05 -0400 Subject: obtained gcc-4.6.4.tar.bz2 from upstream website; verified gcc-4.6.4.tar.bz2.sig; imported gcc-4.6.4 source tree from verified upstream tarball. downloading a git-generated archive based on the 'upstream' tag should provide you with a source tree that is binary identical to the one extracted from the above tarball. if you have obtained the source via the command 'git clone', however, do note that line-endings of files in your working directory might differ from line-endings of the respective files in the upstream repository. --- libgo/go/json/decode.go | 861 ++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 861 insertions(+) create mode 100644 libgo/go/json/decode.go (limited to 'libgo/go/json/decode.go') diff --git a/libgo/go/json/decode.go b/libgo/go/json/decode.go new file mode 100644 index 000000000..ff91dd83c --- /dev/null +++ b/libgo/go/json/decode.go @@ -0,0 +1,861 @@ +// 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. + +// Represents JSON data structure using native Go types: booleans, floats, +// strings, arrays, and maps. + +package json + +import ( + "container/vector" + "os" + "reflect" + "runtime" + "strconv" + "strings" + "unicode" + "utf16" + "utf8" +) + +// Unmarshal parses the JSON-encoded data and stores the result +// in the value pointed to by v. +// +// Unmarshal traverses the value v recursively. +// If an encountered value implements the Unmarshaler interface, +// Unmarshal calls its UnmarshalJSON method with a well-formed +// JSON encoding. +// +// Otherwise, Unmarshal uses the inverse of the encodings that +// Marshal uses, allocating maps, slices, and pointers as necessary, +// with the following additional rules: +// +// To unmarshal a JSON value into a nil interface value, the +// type stored in the interface value is one of: +// +// bool, for JSON booleans +// float64, for JSON numbers +// string, for JSON strings +// []interface{}, for JSON arrays +// map[string]interface{}, for JSON objects +// nil for JSON null +// +// If a JSON value is not appropriate for a given target type, +// or if a JSON number overflows the target type, Unmarshal +// skips that field and completes the unmarshalling as best it can. +// If no more serious errors are encountered, Unmarshal returns +// an UnmarshalTypeError describing the earliest such error. +// +func Unmarshal(data []byte, v interface{}) os.Error { + d := new(decodeState).init(data) + + // Quick check for well-formedness. + // Avoids filling out half a data structure + // before discovering a JSON syntax error. + err := checkValid(data, &d.scan) + if err != nil { + return err + } + + return d.unmarshal(v) +} + +// Unmarshaler is the interface implemented by objects +// that can unmarshal a JSON description of themselves. +// The input can be assumed to be a valid JSON object +// encoding. UnmarshalJSON must copy the JSON data +// if it wishes to retain the data after returning. +type Unmarshaler interface { + UnmarshalJSON([]byte) os.Error +} + + +// An UnmarshalTypeError describes a JSON value that was +// not appropriate for a value of a specific Go type. +type UnmarshalTypeError struct { + Value string // description of JSON value - "bool", "array", "number -5" + Type reflect.Type // type of Go value it could not be assigned to +} + +func (e *UnmarshalTypeError) String() string { + return "json: cannot unmarshal " + e.Value + " into Go value of type " + e.Type.String() +} + +// An UnmarshalFieldError describes a JSON object key that +// led to an unexported (and therefore unwritable) struct field. +type UnmarshalFieldError struct { + Key string + Type *reflect.StructType + Field reflect.StructField +} + +func (e *UnmarshalFieldError) String() string { + return "json: cannot unmarshal object key " + strconv.Quote(e.Key) + " into unexported field " + e.Field.Name + " of type " + e.Type.String() +} + +// An InvalidUnmarshalError describes an invalid argument passed to Unmarshal. +// (The argument to Unmarshal must be a non-nil pointer.) +type InvalidUnmarshalError struct { + Type reflect.Type +} + +func (e *InvalidUnmarshalError) String() string { + if e.Type == nil { + return "json: Unmarshal(nil)" + } + + if _, ok := e.Type.(*reflect.PtrType); !ok { + return "json: Unmarshal(non-pointer " + e.Type.String() + ")" + } + return "json: Unmarshal(nil " + e.Type.String() + ")" +} + +func (d *decodeState) unmarshal(v interface{}) (err os.Error) { + defer func() { + if r := recover(); r != nil { + if _, ok := r.(runtime.Error); ok { + panic(r) + } + err = r.(os.Error) + } + }() + + rv := reflect.NewValue(v) + pv, ok := rv.(*reflect.PtrValue) + if !ok || pv.IsNil() { + return &InvalidUnmarshalError{reflect.Typeof(v)} + } + + d.scan.reset() + // We decode rv not pv.Elem because the Unmarshaler interface + // test must be applied at the top level of the value. + d.value(rv) + return d.savedError +} + +// decodeState represents the state while decoding a JSON value. +type decodeState struct { + data []byte + off int // read offset in data + scan scanner + nextscan scanner // for calls to nextValue + savedError os.Error +} + +// errPhase is used for errors that should not happen unless +// there is a bug in the JSON decoder or something is editing +// the data slice while the decoder executes. +var errPhase = os.NewError("JSON decoder out of sync - data changing underfoot?") + +func (d *decodeState) init(data []byte) *decodeState { + d.data = data + d.off = 0 + d.savedError = nil + return d +} + +// error aborts the decoding by panicking with err. +func (d *decodeState) error(err os.Error) { + panic(err) +} + +// saveError saves the first err it is called with, +// for reporting at the end of the unmarshal. +func (d *decodeState) saveError(err os.Error) { + if d.savedError == nil { + d.savedError = err + } +} + +// next cuts off and returns the next full JSON value in d.data[d.off:]. +// The next value is known to be an object or array, not a literal. +func (d *decodeState) next() []byte { + c := d.data[d.off] + item, rest, err := nextValue(d.data[d.off:], &d.nextscan) + if err != nil { + d.error(err) + } + d.off = len(d.data) - len(rest) + + // Our scanner has seen the opening brace/bracket + // and thinks we're still in the middle of the object. + // invent a closing brace/bracket to get it out. + if c == '{' { + d.scan.step(&d.scan, '}') + } else { + d.scan.step(&d.scan, ']') + } + + return item +} + +// scanWhile processes bytes in d.data[d.off:] until it +// receives a scan code not equal to op. +// It updates d.off and returns the new scan code. +func (d *decodeState) scanWhile(op int) int { + var newOp int + for { + if d.off >= len(d.data) { + newOp = d.scan.eof() + d.off = len(d.data) + 1 // mark processed EOF with len+1 + } else { + c := int(d.data[d.off]) + d.off++ + newOp = d.scan.step(&d.scan, c) + } + if newOp != op { + break + } + } + return newOp +} + +// value decodes a JSON value from d.data[d.off:] into the value. +// it updates d.off to point past the decoded value. +func (d *decodeState) value(v reflect.Value) { + if v == nil { + _, rest, err := nextValue(d.data[d.off:], &d.nextscan) + if err != nil { + d.error(err) + } + d.off = len(d.data) - len(rest) + + // d.scan thinks we're still at the beginning of the item. + // Feed in an empty string - the shortest, simplest value - + // so that it knows we got to the end of the value. + if d.scan.step == stateRedo { + panic("redo") + } + d.scan.step(&d.scan, '"') + d.scan.step(&d.scan, '"') + return + } + + switch op := d.scanWhile(scanSkipSpace); op { + default: + d.error(errPhase) + + case scanBeginArray: + d.array(v) + + case scanBeginObject: + d.object(v) + + case scanBeginLiteral: + d.literal(v) + } +} + +// indirect walks down v allocating pointers as needed, +// until it gets to a non-pointer. +// if it encounters an Unmarshaler, indirect stops and returns that. +// if wantptr is true, indirect stops at the last pointer. +func (d *decodeState) indirect(v reflect.Value, wantptr bool) (Unmarshaler, reflect.Value) { + for { + var isUnmarshaler bool + if v.Type().NumMethod() > 0 { + // Remember that this is an unmarshaler, + // but wait to return it until after allocating + // the pointer (if necessary). + _, isUnmarshaler = v.Interface().(Unmarshaler) + } + + if iv, ok := v.(*reflect.InterfaceValue); ok && !iv.IsNil() { + v = iv.Elem() + continue + } + pv, ok := v.(*reflect.PtrValue) + if !ok { + break + } + _, isptrptr := pv.Elem().(*reflect.PtrValue) + if !isptrptr && wantptr && !isUnmarshaler { + return nil, pv + } + if pv.IsNil() { + pv.PointTo(reflect.MakeZero(pv.Type().(*reflect.PtrType).Elem())) + } + if isUnmarshaler { + // Using v.Interface().(Unmarshaler) + // here means that we have to use a pointer + // as the struct field. We cannot use a value inside + // a pointer to a struct, because in that case + // v.Interface() is the value (x.f) not the pointer (&x.f). + // This is an unfortunate consequence of reflect. + // An alternative would be to look up the + // UnmarshalJSON method and return a FuncValue. + return v.Interface().(Unmarshaler), nil + } + v = pv.Elem() + } + return nil, v +} + +// array consumes an array from d.data[d.off-1:], decoding into the value v. +// the first byte of the array ('[') has been read already. +func (d *decodeState) array(v reflect.Value) { + // Check for unmarshaler. + unmarshaler, pv := d.indirect(v, false) + if unmarshaler != nil { + d.off-- + err := unmarshaler.UnmarshalJSON(d.next()) + if err != nil { + d.error(err) + } + return + } + v = pv + + // Decoding into nil interface? Switch to non-reflect code. + iv, ok := v.(*reflect.InterfaceValue) + if ok { + iv.Set(reflect.NewValue(d.arrayInterface())) + return + } + + // Check type of target. + av, ok := v.(reflect.ArrayOrSliceValue) + if !ok { + d.saveError(&UnmarshalTypeError{"array", v.Type()}) + d.off-- + d.next() + return + } + + sv, _ := v.(*reflect.SliceValue) + + i := 0 + for { + // Look ahead for ] - can only happen on first iteration. + op := d.scanWhile(scanSkipSpace) + if op == scanEndArray { + break + } + + // Back up so d.value can have the byte we just read. + d.off-- + d.scan.undo(op) + + // Get element of array, growing if necessary. + if i >= av.Cap() && sv != nil { + newcap := sv.Cap() + sv.Cap()/2 + if newcap < 4 { + newcap = 4 + } + newv := reflect.MakeSlice(sv.Type().(*reflect.SliceType), sv.Len(), newcap) + reflect.Copy(newv, sv) + sv.Set(newv) + } + if i >= av.Len() && sv != nil { + // Must be slice; gave up on array during i >= av.Cap(). + sv.SetLen(i + 1) + } + + // Decode into element. + if i < av.Len() { + d.value(av.Elem(i)) + } else { + // Ran out of fixed array: skip. + d.value(nil) + } + i++ + + // Next token must be , or ]. + op = d.scanWhile(scanSkipSpace) + if op == scanEndArray { + break + } + if op != scanArrayValue { + d.error(errPhase) + } + } + if i < av.Len() { + if sv == nil { + // Array. Zero the rest. + z := reflect.MakeZero(av.Type().(*reflect.ArrayType).Elem()) + for ; i < av.Len(); i++ { + av.Elem(i).SetValue(z) + } + } else { + sv.SetLen(i) + } + } +} + +// matchName returns true if key should be written to a field named name. +func matchName(key, name string) bool { + return strings.ToLower(key) == strings.ToLower(name) +} + +// object consumes an object from d.data[d.off-1:], decoding into the value v. +// the first byte of the object ('{') has been read already. +func (d *decodeState) object(v reflect.Value) { + // Check for unmarshaler. + unmarshaler, pv := d.indirect(v, false) + if unmarshaler != nil { + d.off-- + err := unmarshaler.UnmarshalJSON(d.next()) + if err != nil { + d.error(err) + } + return + } + v = pv + + // Decoding into nil interface? Switch to non-reflect code. + iv, ok := v.(*reflect.InterfaceValue) + if ok { + iv.Set(reflect.NewValue(d.objectInterface())) + return + } + + // Check type of target: struct or map[string]T + var ( + mv *reflect.MapValue + sv *reflect.StructValue + ) + switch v := v.(type) { + case *reflect.MapValue: + // map must have string type + t := v.Type().(*reflect.MapType) + if t.Key() != reflect.Typeof("") { + d.saveError(&UnmarshalTypeError{"object", v.Type()}) + break + } + mv = v + if mv.IsNil() { + mv.SetValue(reflect.MakeMap(t)) + } + case *reflect.StructValue: + sv = v + default: + d.saveError(&UnmarshalTypeError{"object", v.Type()}) + } + + if mv == nil && sv == nil { + d.off-- + d.next() // skip over { } in input + return + } + + for { + // Read opening " of string key or closing }. + op := d.scanWhile(scanSkipSpace) + if op == scanEndObject { + // closing } - can only happen on first iteration. + break + } + if op != scanBeginLiteral { + d.error(errPhase) + } + + // Read string key. + start := d.off - 1 + op = d.scanWhile(scanContinue) + item := d.data[start : d.off-1] + key, ok := unquote(item) + if !ok { + d.error(errPhase) + } + + // Figure out field corresponding to key. + var subv reflect.Value + if mv != nil { + subv = reflect.MakeZero(mv.Type().(*reflect.MapType).Elem()) + } else { + var f reflect.StructField + var ok bool + // First try for field with that tag. + st := sv.Type().(*reflect.StructType) + for i := 0; i < sv.NumField(); i++ { + f = st.Field(i) + if f.Tag == key { + ok = true + break + } + } + if !ok { + // Second, exact match. + f, ok = st.FieldByName(key) + } + if !ok { + // Third, case-insensitive match. + f, ok = st.FieldByNameFunc(func(s string) bool { return matchName(key, s) }) + } + + // Extract value; name must be exported. + if ok { + if f.PkgPath != "" { + d.saveError(&UnmarshalFieldError{key, st, f}) + } else { + subv = sv.FieldByIndex(f.Index) + } + } + } + + // Read : before value. + if op == scanSkipSpace { + op = d.scanWhile(scanSkipSpace) + } + if op != scanObjectKey { + d.error(errPhase) + } + + // Read value. + d.value(subv) + + // Write value back to map; + // if using struct, subv points into struct already. + if mv != nil { + mv.SetElem(reflect.NewValue(key), subv) + } + + // Next token must be , or }. + op = d.scanWhile(scanSkipSpace) + if op == scanEndObject { + break + } + if op != scanObjectValue { + d.error(errPhase) + } + } +} + +// literal consumes a literal from d.data[d.off-1:], decoding into the value v. +// The first byte of the literal has been read already +// (that's how the caller knows it's a literal). +func (d *decodeState) literal(v reflect.Value) { + // All bytes inside literal return scanContinue op code. + start := d.off - 1 + op := d.scanWhile(scanContinue) + + // Scan read one byte too far; back up. + d.off-- + d.scan.undo(op) + item := d.data[start:d.off] + + // Check for unmarshaler. + wantptr := item[0] == 'n' // null + unmarshaler, pv := d.indirect(v, wantptr) + if unmarshaler != nil { + err := unmarshaler.UnmarshalJSON(item) + if err != nil { + d.error(err) + } + return + } + v = pv + + switch c := item[0]; c { + case 'n': // null + switch v.(type) { + default: + d.saveError(&UnmarshalTypeError{"null", v.Type()}) + case *reflect.InterfaceValue, *reflect.PtrValue, *reflect.MapValue: + v.SetValue(nil) + } + + case 't', 'f': // true, false + value := c == 't' + switch v := v.(type) { + default: + d.saveError(&UnmarshalTypeError{"bool", v.Type()}) + case *reflect.BoolValue: + v.Set(value) + case *reflect.InterfaceValue: + v.Set(reflect.NewValue(value)) + } + + case '"': // string + s, ok := unquote(item) + if !ok { + d.error(errPhase) + } + switch v := v.(type) { + default: + d.saveError(&UnmarshalTypeError{"string", v.Type()}) + case *reflect.StringValue: + v.Set(s) + case *reflect.InterfaceValue: + v.Set(reflect.NewValue(s)) + } + + default: // number + if c != '-' && (c < '0' || c > '9') { + d.error(errPhase) + } + s := string(item) + switch v := v.(type) { + default: + d.error(&UnmarshalTypeError{"number", v.Type()}) + case *reflect.InterfaceValue: + n, err := strconv.Atof64(s) + if err != nil { + d.saveError(&UnmarshalTypeError{"number " + s, v.Type()}) + break + } + v.Set(reflect.NewValue(n)) + + case *reflect.IntValue: + n, err := strconv.Atoi64(s) + if err != nil || v.Overflow(n) { + d.saveError(&UnmarshalTypeError{"number " + s, v.Type()}) + break + } + v.Set(n) + + case *reflect.UintValue: + n, err := strconv.Atoui64(s) + if err != nil || v.Overflow(n) { + d.saveError(&UnmarshalTypeError{"number " + s, v.Type()}) + break + } + v.Set(n) + + case *reflect.FloatValue: + n, err := strconv.AtofN(s, v.Type().Bits()) + if err != nil || v.Overflow(n) { + d.saveError(&UnmarshalTypeError{"number " + s, v.Type()}) + break + } + v.Set(n) + } + } +} + +// The xxxInterface routines build up a value to be stored +// in an empty interface. They are not strictly necessary, +// but they avoid the weight of reflection in this common case. + +// valueInterface is like value but returns interface{} +func (d *decodeState) valueInterface() interface{} { + switch d.scanWhile(scanSkipSpace) { + default: + d.error(errPhase) + case scanBeginArray: + return d.arrayInterface() + case scanBeginObject: + return d.objectInterface() + case scanBeginLiteral: + return d.literalInterface() + } + panic("unreachable") +} + +// arrayInterface is like array but returns []interface{}. +func (d *decodeState) arrayInterface() []interface{} { + var v vector.Vector + for { + // Look ahead for ] - can only happen on first iteration. + op := d.scanWhile(scanSkipSpace) + if op == scanEndArray { + break + } + + // Back up so d.value can have the byte we just read. + d.off-- + d.scan.undo(op) + + v.Push(d.valueInterface()) + + // Next token must be , or ]. + op = d.scanWhile(scanSkipSpace) + if op == scanEndArray { + break + } + if op != scanArrayValue { + d.error(errPhase) + } + } + return v +} + +// objectInterface is like object but returns map[string]interface{}. +func (d *decodeState) objectInterface() map[string]interface{} { + m := make(map[string]interface{}) + for { + // Read opening " of string key or closing }. + op := d.scanWhile(scanSkipSpace) + if op == scanEndObject { + // closing } - can only happen on first iteration. + break + } + if op != scanBeginLiteral { + d.error(errPhase) + } + + // Read string key. + start := d.off - 1 + op = d.scanWhile(scanContinue) + item := d.data[start : d.off-1] + key, ok := unquote(item) + if !ok { + d.error(errPhase) + } + + // Read : before value. + if op == scanSkipSpace { + op = d.scanWhile(scanSkipSpace) + } + if op != scanObjectKey { + d.error(errPhase) + } + + // Read value. + m[key] = d.valueInterface() + + // Next token must be , or }. + op = d.scanWhile(scanSkipSpace) + if op == scanEndObject { + break + } + if op != scanObjectValue { + d.error(errPhase) + } + } + return m +} + + +// literalInterface is like literal but returns an interface value. +func (d *decodeState) literalInterface() interface{} { + // All bytes inside literal return scanContinue op code. + start := d.off - 1 + op := d.scanWhile(scanContinue) + + // Scan read one byte too far; back up. + d.off-- + d.scan.undo(op) + item := d.data[start:d.off] + + switch c := item[0]; c { + case 'n': // null + return nil + + case 't', 'f': // true, false + return c == 't' + + case '"': // string + s, ok := unquote(item) + if !ok { + d.error(errPhase) + } + return s + + default: // number + if c != '-' && (c < '0' || c > '9') { + d.error(errPhase) + } + n, err := strconv.Atof64(string(item)) + if err != nil { + d.saveError(&UnmarshalTypeError{"number " + string(item), reflect.Typeof(0.0)}) + } + return n + } + panic("unreachable") +} + +// getu4 decodes \uXXXX from the beginning of s, returning the hex value, +// or it returns -1. +func getu4(s []byte) int { + if len(s) < 6 || s[0] != '\\' || s[1] != 'u' { + return -1 + } + rune, err := strconv.Btoui64(string(s[2:6]), 16) + if err != nil { + return -1 + } + return int(rune) +} + +// unquote converts a quoted JSON string literal s into an actual string t. +// The rules are different than for Go, so cannot use strconv.Unquote. +func unquote(s []byte) (t string, ok bool) { + if len(s) < 2 || s[0] != '"' || s[len(s)-1] != '"' { + return + } + b := make([]byte, len(s)+2*utf8.UTFMax) + w := 0 + for r := 1; r < len(s)-1; { + // Out of room? Can only happen if s is full of + // malformed UTF-8 and we're replacing each + // byte with RuneError. + if w >= len(b)-2*utf8.UTFMax { + nb := make([]byte, (len(b)+utf8.UTFMax)*2) + copy(nb, b[0:w]) + b = nb + } + switch c := s[r]; { + case c == '\\': + r++ + if r >= len(s)-1 { + return + } + switch s[r] { + default: + return + case '"', '\\', '/', '\'': + b[w] = s[r] + r++ + w++ + case 'b': + b[w] = '\b' + r++ + w++ + case 'f': + b[w] = '\f' + r++ + w++ + case 'n': + b[w] = '\n' + r++ + w++ + case 'r': + b[w] = '\r' + r++ + w++ + case 't': + b[w] = '\t' + r++ + w++ + case 'u': + r-- + rune := getu4(s[r:]) + if rune < 0 { + return + } + r += 6 + if utf16.IsSurrogate(rune) { + rune1 := getu4(s[r:]) + if dec := utf16.DecodeRune(rune, rune1); dec != unicode.ReplacementChar { + // A valid pair; consume. + r += 6 + w += utf8.EncodeRune(b[w:], dec) + break + } + // Invalid surrogate; fall back to replacement rune. + rune = unicode.ReplacementChar + } + w += utf8.EncodeRune(b[w:], rune) + } + + // Quote, control characters are invalid. + case c == '"', c < ' ': + return + + // ASCII + case c < utf8.RuneSelf: + b[w] = c + r++ + w++ + + // Coerce to well-formed UTF-8. + default: + rune, size := utf8.DecodeRune(s[r:]) + r += size + w += utf8.EncodeRune(b[w:], rune) + } + } + return string(b[0:w]), true +} -- cgit v1.2.3