diff --git a/go/vendor/github.com/globalsign/mgo/internal/json/decode.go b/go/vendor/github.com/globalsign/mgo/internal/json/decode.go
new file mode 100644
index 0000000..d5ca1f9
--- /dev/null
+++ b/go/vendor/github.com/globalsign/mgo/internal/json/decode.go
@@ -0,0 +1,1685 @@
+// 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 (
+	"bytes"
+	"encoding"
+	"encoding/base64"
+	"errors"
+	"fmt"
+	"reflect"
+	"runtime"
+	"strconv"
+	"unicode"
+	"unicode/utf16"
+	"unicode/utf8"
+)
+
+// Unmarshal parses the JSON-encoded data and stores the result
+// in the value pointed to by v.
+//
+// Unmarshal uses the inverse of the encodings that
+// Marshal uses, allocating maps, slices, and pointers as necessary,
+// with the following additional rules:
+//
+// To unmarshal JSON into a pointer, Unmarshal first handles the case of
+// the JSON being the JSON literal null. In that case, Unmarshal sets
+// the pointer to nil. Otherwise, Unmarshal unmarshals the JSON into
+// the value pointed at by the pointer. If the pointer is nil, Unmarshal
+// allocates a new value for it to point to.
+//
+// To unmarshal JSON into a struct, Unmarshal matches incoming object
+// keys to the keys used by Marshal (either the struct field name or its tag),
+// preferring an exact match but also accepting a case-insensitive match.
+// Unmarshal will only set exported fields of the struct.
+//
+// To unmarshal JSON into an interface value,
+// Unmarshal stores one of these in the interface value:
+//
+//	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
+//
+// To unmarshal a JSON array into a slice, Unmarshal resets the slice length
+// to zero and then appends each element to the slice.
+// As a special case, to unmarshal an empty JSON array into a slice,
+// Unmarshal replaces the slice with a new empty slice.
+//
+// To unmarshal a JSON array into a Go array, Unmarshal decodes
+// JSON array elements into corresponding Go array elements.
+// If the Go array is smaller than the JSON array,
+// the additional JSON array elements are discarded.
+// If the JSON array is smaller than the Go array,
+// the additional Go array elements are set to zero values.
+//
+// To unmarshal a JSON object into a map, Unmarshal first establishes a map to
+// use, If the map is nil, Unmarshal allocates a new map. Otherwise Unmarshal
+// reuses the existing map, keeping existing entries. Unmarshal then stores key-
+// value pairs from the JSON object into the map.  The map's key type must
+// either be a string or implement encoding.TextUnmarshaler.
+//
+// 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 unmarshaling as best it can.
+// If no more serious errors are encountered, Unmarshal returns
+// an UnmarshalTypeError describing the earliest such error.
+//
+// The JSON null value unmarshals into an interface, map, pointer, or slice
+// by setting that Go value to nil. Because null is often used in JSON to mean
+// ``not present,'' unmarshaling a JSON null into any other Go type has no effect
+// on the value and produces no error.
+//
+// When unmarshaling quoted strings, invalid UTF-8 or
+// invalid UTF-16 surrogate pairs are not treated as an error.
+// Instead, they are replaced by the Unicode replacement
+// character U+FFFD.
+//
+func Unmarshal(data []byte, v interface{}) error {
+	// Check for well-formedness.
+	// Avoids filling out half a data structure
+	// before discovering a JSON syntax error.
+	var d decodeState
+	err := checkValid(data, &d.scan)
+	if err != nil {
+		return err
+	}
+
+	d.init(data)
+	return d.unmarshal(v)
+}
+
+// Unmarshaler is the interface implemented by types
+// that can unmarshal a JSON description of themselves.
+// The input can be assumed to be a valid encoding of
+// a JSON value. UnmarshalJSON must copy the JSON data
+// if it wishes to retain the data after returning.
+type Unmarshaler interface {
+	UnmarshalJSON([]byte) 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
+	Offset int64        // error occurred after reading Offset bytes
+}
+
+func (e *UnmarshalTypeError) Error() 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.
+// (No longer used; kept for compatibility.)
+type UnmarshalFieldError struct {
+	Key   string
+	Type  reflect.Type
+	Field reflect.StructField
+}
+
+func (e *UnmarshalFieldError) Error() 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) Error() string {
+	if e.Type == nil {
+		return "json: Unmarshal(nil)"
+	}
+
+	if e.Type.Kind() != reflect.Ptr {
+		return "json: Unmarshal(non-pointer " + e.Type.String() + ")"
+	}
+	return "json: Unmarshal(nil " + e.Type.String() + ")"
+}
+
+func (d *decodeState) unmarshal(v interface{}) (err error) {
+	defer func() {
+		if r := recover(); r != nil {
+			if _, ok := r.(runtime.Error); ok {
+				panic(r)
+			}
+			err = r.(error)
+		}
+	}()
+
+	rv := reflect.ValueOf(v)
+	if rv.Kind() != reflect.Ptr || rv.IsNil() {
+		return &InvalidUnmarshalError{reflect.TypeOf(v)}
+	}
+
+	d.scan.reset()
+	// We decode rv not rv.Elem because the Unmarshaler interface
+	// test must be applied at the top level of the value.
+	d.value(rv)
+	return d.savedError
+}
+
+// A Number represents a JSON number literal.
+type Number string
+
+// String returns the literal text of the number.
+func (n Number) String() string { return string(n) }
+
+// Float64 returns the number as a float64.
+func (n Number) Float64() (float64, error) {
+	return strconv.ParseFloat(string(n), 64)
+}
+
+// Int64 returns the number as an int64.
+func (n Number) Int64() (int64, error) {
+	return strconv.ParseInt(string(n), 10, 64)
+}
+
+// isValidNumber reports whether s is a valid JSON number literal.
+func isValidNumber(s string) bool {
+	// This function implements the JSON numbers grammar.
+	// See https://tools.ietf.org/html/rfc7159#section-6
+	// and http://json.org/number.gif
+
+	if s == "" {
+		return false
+	}
+
+	// Optional -
+	if s[0] == '-' {
+		s = s[1:]
+		if s == "" {
+			return false
+		}
+	}
+
+	// Digits
+	switch {
+	default:
+		return false
+
+	case s[0] == '0':
+		s = s[1:]
+
+	case '1' <= s[0] && s[0] <= '9':
+		s = s[1:]
+		for len(s) > 0 && '0' <= s[0] && s[0] <= '9' {
+			s = s[1:]
+		}
+	}
+
+	// . followed by 1 or more digits.
+	if len(s) >= 2 && s[0] == '.' && '0' <= s[1] && s[1] <= '9' {
+		s = s[2:]
+		for len(s) > 0 && '0' <= s[0] && s[0] <= '9' {
+			s = s[1:]
+		}
+	}
+
+	// e or E followed by an optional - or + and
+	// 1 or more digits.
+	if len(s) >= 2 && (s[0] == 'e' || s[0] == 'E') {
+		s = s[1:]
+		if s[0] == '+' || s[0] == '-' {
+			s = s[1:]
+			if s == "" {
+				return false
+			}
+		}
+		for len(s) > 0 && '0' <= s[0] && s[0] <= '9' {
+			s = s[1:]
+		}
+	}
+
+	// Make sure we are at the end.
+	return s == ""
+}
+
+// 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 error
+	useNumber  bool
+	ext        Extension
+}
+
+// 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 = errors.New("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 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 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 if c == '[' {
+		d.scan.step(&d.scan, ']')
+	} else {
+		// Was inside a function name. Get out of it.
+		d.scan.step(&d.scan, '(')
+		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 := 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.IsValid() {
+		_, 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.redo {
+			// rewind.
+			d.scan.redo = false
+			d.scan.step = stateBeginValue
+		}
+		d.scan.step(&d.scan, '"')
+		d.scan.step(&d.scan, '"')
+
+		n := len(d.scan.parseState)
+		if n > 0 && d.scan.parseState[n-1] == parseObjectKey {
+			// d.scan thinks we just read an object key; finish the object
+			d.scan.step(&d.scan, ':')
+			d.scan.step(&d.scan, '"')
+			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)
+
+	case scanBeginName:
+		d.name(v)
+	}
+}
+
+type unquotedValue struct{}
+
+// valueQuoted is like value but decodes a
+// quoted string literal or literal null into an interface value.
+// If it finds anything other than a quoted string literal or null,
+// valueQuoted returns unquotedValue{}.
+func (d *decodeState) valueQuoted() interface{} {
+	switch op := d.scanWhile(scanSkipSpace); op {
+	default:
+		d.error(errPhase)
+
+	case scanBeginArray:
+		d.array(reflect.Value{})
+
+	case scanBeginObject:
+		d.object(reflect.Value{})
+
+	case scanBeginName:
+		switch v := d.nameInterface().(type) {
+		case nil, string:
+			return v
+		}
+
+	case scanBeginLiteral:
+		switch v := d.literalInterface().(type) {
+		case nil, string:
+			return v
+		}
+	}
+	return unquotedValue{}
+}
+
+// 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 decodingNull is true, indirect stops at the last pointer so it can be set to nil.
+func (d *decodeState) indirect(v reflect.Value, decodingNull bool) (Unmarshaler, encoding.TextUnmarshaler, reflect.Value) {
+	// If v is a named type and is addressable,
+	// start with its address, so that if the type has pointer methods,
+	// we find them.
+	if v.Kind() != reflect.Ptr && v.Type().Name() != "" && v.CanAddr() {
+		v = v.Addr()
+	}
+	for {
+		// Load value from interface, but only if the result will be
+		// usefully addressable.
+		if v.Kind() == reflect.Interface && !v.IsNil() {
+			e := v.Elem()
+			if e.Kind() == reflect.Ptr && !e.IsNil() && (!decodingNull || e.Elem().Kind() == reflect.Ptr) {
+				v = e
+				continue
+			}
+		}
+
+		if v.Kind() != reflect.Ptr {
+			break
+		}
+
+		if v.Elem().Kind() != reflect.Ptr && decodingNull && v.CanSet() {
+			break
+		}
+		if v.IsNil() {
+			v.Set(reflect.New(v.Type().Elem()))
+		}
+		if v.Type().NumMethod() > 0 {
+			if u, ok := v.Interface().(Unmarshaler); ok {
+				return u, nil, v
+			}
+			if u, ok := v.Interface().(encoding.TextUnmarshaler); ok {
+				return nil, u, v
+			}
+		}
+		v = v.Elem()
+	}
+	return nil, 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.
+	u, ut, pv := d.indirect(v, false)
+	if u != nil {
+		d.off--
+		err := u.UnmarshalJSON(d.next())
+		if err != nil {
+			d.error(err)
+		}
+		return
+	}
+	if ut != nil {
+		d.saveError(&UnmarshalTypeError{"array", v.Type(), int64(d.off)})
+		d.off--
+		d.next()
+		return
+	}
+
+	v = pv
+
+	// Check type of target.
+	switch v.Kind() {
+	case reflect.Interface:
+		if v.NumMethod() == 0 {
+			// Decoding into nil interface?  Switch to non-reflect code.
+			v.Set(reflect.ValueOf(d.arrayInterface()))
+			return
+		}
+		// Otherwise it's invalid.
+		fallthrough
+	default:
+		d.saveError(&UnmarshalTypeError{"array", v.Type(), int64(d.off)})
+		d.off--
+		d.next()
+		return
+	case reflect.Array:
+	case reflect.Slice:
+		break
+	}
+
+	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 v.Kind() == reflect.Slice {
+			// Grow slice if necessary
+			if i >= v.Cap() {
+				newcap := v.Cap() + v.Cap()/2
+				if newcap < 4 {
+					newcap = 4
+				}
+				newv := reflect.MakeSlice(v.Type(), v.Len(), newcap)
+				reflect.Copy(newv, v)
+				v.Set(newv)
+			}
+			if i >= v.Len() {
+				v.SetLen(i + 1)
+			}
+		}
+
+		if i < v.Len() {
+			// Decode into element.
+			d.value(v.Index(i))
+		} else {
+			// Ran out of fixed array: skip.
+			d.value(reflect.Value{})
+		}
+		i++
+
+		// Next token must be , or ].
+		op = d.scanWhile(scanSkipSpace)
+		if op == scanEndArray {
+			break
+		}
+		if op != scanArrayValue {
+			d.error(errPhase)
+		}
+	}
+
+	if i < v.Len() {
+		if v.Kind() == reflect.Array {
+			// Array. Zero the rest.
+			z := reflect.Zero(v.Type().Elem())
+			for ; i < v.Len(); i++ {
+				v.Index(i).Set(z)
+			}
+		} else {
+			v.SetLen(i)
+		}
+	}
+	if i == 0 && v.Kind() == reflect.Slice {
+		v.Set(reflect.MakeSlice(v.Type(), 0, 0))
+	}
+}
+
+var nullLiteral = []byte("null")
+var textUnmarshalerType = reflect.TypeOf(new(encoding.TextUnmarshaler)).Elem()
+
+// 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.
+	u, ut, pv := d.indirect(v, false)
+	if d.storeKeyed(pv) {
+		return
+	}
+	if u != nil {
+		d.off--
+		err := u.UnmarshalJSON(d.next())
+		if err != nil {
+			d.error(err)
+		}
+		return
+	}
+	if ut != nil {
+		d.saveError(&UnmarshalTypeError{"object", v.Type(), int64(d.off)})
+		d.off--
+		d.next() // skip over { } in input
+		return
+	}
+	v = pv
+
+	// Decoding into nil interface?  Switch to non-reflect code.
+	if v.Kind() == reflect.Interface && v.NumMethod() == 0 {
+		v.Set(reflect.ValueOf(d.objectInterface()))
+		return
+	}
+
+	// Check type of target:
+	//   struct or
+	//   map[string]T or map[encoding.TextUnmarshaler]T
+	switch v.Kind() {
+	case reflect.Map:
+		// Map key must either have string kind or be an encoding.TextUnmarshaler.
+		t := v.Type()
+		if t.Key().Kind() != reflect.String &&
+			!reflect.PtrTo(t.Key()).Implements(textUnmarshalerType) {
+			d.saveError(&UnmarshalTypeError{"object", v.Type(), int64(d.off)})
+			d.off--
+			d.next() // skip over { } in input
+			return
+		}
+		if v.IsNil() {
+			v.Set(reflect.MakeMap(t))
+		}
+	case reflect.Struct:
+
+	default:
+		d.saveError(&UnmarshalTypeError{"object", v.Type(), int64(d.off)})
+		d.off--
+		d.next() // skip over { } in input
+		return
+	}
+
+	var mapElem reflect.Value
+
+	empty := true
+	for {
+		// Read opening " of string key or closing }.
+		op := d.scanWhile(scanSkipSpace)
+		if op == scanEndObject {
+			if !empty && !d.ext.trailingCommas {
+				d.syntaxError("beginning of object key string")
+			}
+			break
+		}
+		empty = false
+		if op == scanBeginName {
+			if !d.ext.unquotedKeys {
+				d.syntaxError("beginning of object key string")
+			}
+		} else if op != scanBeginLiteral {
+			d.error(errPhase)
+		}
+		unquotedKey := op == scanBeginName
+
+		// Read key.
+		start := d.off - 1
+		op = d.scanWhile(scanContinue)
+		item := d.data[start : d.off-1]
+		var key []byte
+		if unquotedKey {
+			key = item
+			// TODO Fix code below to quote item when necessary.
+		} else {
+			var ok bool
+			key, ok = unquoteBytes(item)
+			if !ok {
+				d.error(errPhase)
+			}
+		}
+
+		// Figure out field corresponding to key.
+		var subv reflect.Value
+		destring := false // whether the value is wrapped in a string to be decoded first
+
+		if v.Kind() == reflect.Map {
+			elemType := v.Type().Elem()
+			if !mapElem.IsValid() {
+				mapElem = reflect.New(elemType).Elem()
+			} else {
+				mapElem.Set(reflect.Zero(elemType))
+			}
+			subv = mapElem
+		} else {
+			var f *field
+			fields := cachedTypeFields(v.Type())
+			for i := range fields {
+				ff := &fields[i]
+				if bytes.Equal(ff.nameBytes, key) {
+					f = ff
+					break
+				}
+				if f == nil && ff.equalFold(ff.nameBytes, key) {
+					f = ff
+				}
+			}
+			if f != nil {
+				subv = v
+				destring = f.quoted
+				for _, i := range f.index {
+					if subv.Kind() == reflect.Ptr {
+						if subv.IsNil() {
+							subv.Set(reflect.New(subv.Type().Elem()))
+						}
+						subv = subv.Elem()
+					}
+					subv = subv.Field(i)
+				}
+			}
+		}
+
+		// Read : before value.
+		if op == scanSkipSpace {
+			op = d.scanWhile(scanSkipSpace)
+		}
+		if op != scanObjectKey {
+			d.error(errPhase)
+		}
+
+		// Read value.
+		if destring {
+			switch qv := d.valueQuoted().(type) {
+			case nil:
+				d.literalStore(nullLiteral, subv, false)
+			case string:
+				d.literalStore([]byte(qv), subv, true)
+			default:
+				d.saveError(fmt.Errorf("json: invalid use of ,string struct tag, trying to unmarshal unquoted value into %v", subv.Type()))
+			}
+		} else {
+			d.value(subv)
+		}
+
+		// Write value back to map;
+		// if using struct, subv points into struct already.
+		if v.Kind() == reflect.Map {
+			kt := v.Type().Key()
+			var kv reflect.Value
+			switch {
+			case kt.Kind() == reflect.String:
+				kv = reflect.ValueOf(key).Convert(v.Type().Key())
+			case reflect.PtrTo(kt).Implements(textUnmarshalerType):
+				kv = reflect.New(v.Type().Key())
+				d.literalStore(item, kv, true)
+				kv = kv.Elem()
+			default:
+				panic("json: Unexpected key type") // should never occur
+			}
+			v.SetMapIndex(kv, subv)
+		}
+
+		// Next token must be , or }.
+		op = d.scanWhile(scanSkipSpace)
+		if op == scanEndObject {
+			break
+		}
+		if op != scanObjectValue {
+			d.error(errPhase)
+		}
+	}
+}
+
+// isNull returns whether there's a null literal at the provided offset.
+func (d *decodeState) isNull(off int) bool {
+	if off+4 >= len(d.data) || d.data[off] != 'n' || d.data[off+1] != 'u' || d.data[off+2] != 'l' || d.data[off+3] != 'l' {
+		return false
+	}
+	d.nextscan.reset()
+	for i, c := range d.data[off:] {
+		if i > 4 {
+			return false
+		}
+		switch d.nextscan.step(&d.nextscan, c) {
+		case scanContinue, scanBeginName:
+			continue
+		}
+		break
+	}
+	return true
+}
+
+// name consumes a const or function from d.data[d.off-1:], decoding into the value v.
+// the first byte of the function name has been read already.
+func (d *decodeState) name(v reflect.Value) {
+	if d.isNull(d.off - 1) {
+		d.literal(v)
+		return
+	}
+
+	// Check for unmarshaler.
+	u, ut, pv := d.indirect(v, false)
+	if d.storeKeyed(pv) {
+		return
+	}
+	if u != nil {
+		d.off--
+		err := u.UnmarshalJSON(d.next())
+		if err != nil {
+			d.error(err)
+		}
+		return
+	}
+	if ut != nil {
+		d.saveError(&UnmarshalTypeError{"object", v.Type(), int64(d.off)})
+		d.off--
+		d.next() // skip over function in input
+		return
+	}
+	v = pv
+
+	// Decoding into nil interface?  Switch to non-reflect code.
+	if v.Kind() == reflect.Interface && v.NumMethod() == 0 {
+		out := d.nameInterface()
+		if out == nil {
+			v.Set(reflect.Zero(v.Type()))
+		} else {
+			v.Set(reflect.ValueOf(out))
+		}
+		return
+	}
+
+	nameStart := d.off - 1
+
+	op := d.scanWhile(scanContinue)
+
+	name := d.data[nameStart : d.off-1]
+	if op != scanParam {
+		// Back up so the byte just read is consumed next.
+		d.off--
+		d.scan.undo(op)
+		if l, ok := d.convertLiteral(name); ok {
+			d.storeValue(v, l)
+			return
+		}
+		d.error(&SyntaxError{fmt.Sprintf("json: unknown constant %q", name), int64(d.off)})
+	}
+
+	funcName := string(name)
+	funcData := d.ext.funcs[funcName]
+	if funcData.key == "" {
+		d.error(fmt.Errorf("json: unknown function %q", funcName))
+	}
+
+	// Check type of target:
+	//   struct or
+	//   map[string]T or map[encoding.TextUnmarshaler]T
+	switch v.Kind() {
+	case reflect.Map:
+		// Map key must either have string kind or be an encoding.TextUnmarshaler.
+		t := v.Type()
+		if t.Key().Kind() != reflect.String &&
+			!reflect.PtrTo(t.Key()).Implements(textUnmarshalerType) {
+			d.saveError(&UnmarshalTypeError{"object", v.Type(), int64(d.off)})
+			d.off--
+			d.next() // skip over { } in input
+			return
+		}
+		if v.IsNil() {
+			v.Set(reflect.MakeMap(t))
+		}
+	case reflect.Struct:
+
+	default:
+		d.saveError(&UnmarshalTypeError{"object", v.Type(), int64(d.off)})
+		d.off--
+		d.next() // skip over { } in input
+		return
+	}
+
+	// TODO Fix case of func field as map.
+	//topv := v
+
+	// Figure out field corresponding to function.
+	key := []byte(funcData.key)
+	if v.Kind() == reflect.Map {
+		elemType := v.Type().Elem()
+		v = reflect.New(elemType).Elem()
+	} else {
+		var f *field
+		fields := cachedTypeFields(v.Type())
+		for i := range fields {
+			ff := &fields[i]
+			if bytes.Equal(ff.nameBytes, key) {
+				f = ff
+				break
+			}
+			if f == nil && ff.equalFold(ff.nameBytes, key) {
+				f = ff
+			}
+		}
+		if f != nil {
+			for _, i := range f.index {
+				if v.Kind() == reflect.Ptr {
+					if v.IsNil() {
+						v.Set(reflect.New(v.Type().Elem()))
+					}
+					v = v.Elem()
+				}
+				v = v.Field(i)
+			}
+			if v.Kind() == reflect.Ptr {
+				if v.IsNil() {
+					v.Set(reflect.New(v.Type().Elem()))
+				}
+				v = v.Elem()
+			}
+		}
+	}
+
+	// Check for unmarshaler on func field itself.
+	u, _, _ = d.indirect(v, false)
+	if u != nil {
+		d.off = nameStart
+		err := u.UnmarshalJSON(d.next())
+		if err != nil {
+			d.error(err)
+		}
+		return
+	}
+
+	var mapElem reflect.Value
+
+	// Parse function arguments.
+	for i := 0; ; i++ {
+		// closing ) - can only happen on first iteration.
+		op := d.scanWhile(scanSkipSpace)
+		if op == scanEndParams {
+			break
+		}
+
+		// Back up so d.value can have the byte we just read.
+		d.off--
+		d.scan.undo(op)
+
+		if i >= len(funcData.args) {
+			d.error(fmt.Errorf("json: too many arguments for function %s", funcName))
+		}
+		key := []byte(funcData.args[i])
+
+		// Figure out field corresponding to key.
+		var subv reflect.Value
+		destring := false // whether the value is wrapped in a string to be decoded first
+
+		if v.Kind() == reflect.Map {
+			elemType := v.Type().Elem()
+			if !mapElem.IsValid() {
+				mapElem = reflect.New(elemType).Elem()
+			} else {
+				mapElem.Set(reflect.Zero(elemType))
+			}
+			subv = mapElem
+		} else {
+			var f *field
+			fields := cachedTypeFields(v.Type())
+			for i := range fields {
+				ff := &fields[i]
+				if bytes.Equal(ff.nameBytes, key) {
+					f = ff
+					break
+				}
+				if f == nil && ff.equalFold(ff.nameBytes, key) {
+					f = ff
+				}
+			}
+			if f != nil {
+				subv = v
+				destring = f.quoted
+				for _, i := range f.index {
+					if subv.Kind() == reflect.Ptr {
+						if subv.IsNil() {
+							subv.Set(reflect.New(subv.Type().Elem()))
+						}
+						subv = subv.Elem()
+					}
+					subv = subv.Field(i)
+				}
+			}
+		}
+
+		// Read value.
+		if destring {
+			switch qv := d.valueQuoted().(type) {
+			case nil:
+				d.literalStore(nullLiteral, subv, false)
+			case string:
+				d.literalStore([]byte(qv), subv, true)
+			default:
+				d.saveError(fmt.Errorf("json: invalid use of ,string struct tag, trying to unmarshal unquoted value into %v", subv.Type()))
+			}
+		} else {
+			d.value(subv)
+		}
+
+		// Write value back to map;
+		// if using struct, subv points into struct already.
+		if v.Kind() == reflect.Map {
+			kt := v.Type().Key()
+			var kv reflect.Value
+			switch {
+			case kt.Kind() == reflect.String:
+				kv = reflect.ValueOf(key).Convert(v.Type().Key())
+			case reflect.PtrTo(kt).Implements(textUnmarshalerType):
+				kv = reflect.New(v.Type().Key())
+				d.literalStore(key, kv, true)
+				kv = kv.Elem()
+			default:
+				panic("json: Unexpected key type") // should never occur
+			}
+			v.SetMapIndex(kv, subv)
+		}
+
+		// Next token must be , or ).
+		op = d.scanWhile(scanSkipSpace)
+		if op == scanEndParams {
+			break
+		}
+		if op != scanParam {
+			d.error(errPhase)
+		}
+	}
+}
+
+// keyed attempts to decode an object or function using a keyed doc extension,
+// and returns the value and true on success, or nil and false otherwise.
+func (d *decodeState) keyed() (interface{}, bool) {
+	if len(d.ext.keyed) == 0 {
+		return nil, false
+	}
+
+	unquote := false
+
+	// Look-ahead first key to check for a keyed document extension.
+	d.nextscan.reset()
+	var start, end int
+	for i, c := range d.data[d.off-1:] {
+		switch op := d.nextscan.step(&d.nextscan, c); op {
+		case scanSkipSpace, scanContinue, scanBeginObject:
+			continue
+		case scanBeginLiteral, scanBeginName:
+			unquote = op == scanBeginLiteral
+			start = i
+			continue
+		}
+		end = i
+		break
+	}
+
+	name := bytes.Trim(d.data[d.off-1+start:d.off-1+end], " \n\t")
+
+	var key []byte
+	var ok bool
+	if unquote {
+		key, ok = unquoteBytes(name)
+		if !ok {
+			d.error(errPhase)
+		}
+	} else {
+		funcData, ok := d.ext.funcs[string(name)]
+		if !ok {
+			return nil, false
+		}
+		key = []byte(funcData.key)
+	}
+
+	decode, ok := d.ext.keyed[string(key)]
+	if !ok {
+		return nil, false
+	}
+
+	d.off--
+	out, err := decode(d.next())
+	if err != nil {
+		d.error(err)
+	}
+	return out, true
+}
+
+func (d *decodeState) storeKeyed(v reflect.Value) bool {
+	keyed, ok := d.keyed()
+	if !ok {
+		return false
+	}
+	d.storeValue(v, keyed)
+	return true
+}
+
+var (
+	trueBytes  = []byte("true")
+	falseBytes = []byte("false")
+	nullBytes  = []byte("null")
+)
+
+func (d *decodeState) storeValue(v reflect.Value, from interface{}) {
+	switch from {
+	case nil:
+		d.literalStore(nullBytes, v, false)
+		return
+	case true:
+		d.literalStore(trueBytes, v, false)
+		return
+	case false:
+		d.literalStore(falseBytes, v, false)
+		return
+	}
+	fromv := reflect.ValueOf(from)
+	for fromv.Kind() == reflect.Ptr && !fromv.IsNil() {
+		fromv = fromv.Elem()
+	}
+	fromt := fromv.Type()
+	for v.Kind() == reflect.Ptr && !v.IsNil() {
+		v = v.Elem()
+	}
+	vt := v.Type()
+	if fromt.AssignableTo(vt) {
+		v.Set(fromv)
+	} else if fromt.ConvertibleTo(vt) {
+		v.Set(fromv.Convert(vt))
+	} else {
+		d.saveError(&UnmarshalTypeError{"object", v.Type(), int64(d.off)})
+	}
+}
+
+func (d *decodeState) convertLiteral(name []byte) (interface{}, bool) {
+	if len(name) == 0 {
+		return nil, false
+	}
+	switch name[0] {
+	case 't':
+		if bytes.Equal(name, trueBytes) {
+			return true, true
+		}
+	case 'f':
+		if bytes.Equal(name, falseBytes) {
+			return false, true
+		}
+	case 'n':
+		if bytes.Equal(name, nullBytes) {
+			return nil, true
+		}
+	}
+	if l, ok := d.ext.consts[string(name)]; ok {
+		return l, true
+	}
+	return nil, false
+}
+
+// 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)
+
+	d.literalStore(d.data[start:d.off], v, false)
+}
+
+// convertNumber converts the number literal s to a float64 or a Number
+// depending on the setting of d.useNumber.
+func (d *decodeState) convertNumber(s string) (interface{}, error) {
+	if d.useNumber {
+		return Number(s), nil
+	}
+	f, err := strconv.ParseFloat(s, 64)
+	if err != nil {
+		return nil, &UnmarshalTypeError{"number " + s, reflect.TypeOf(0.0), int64(d.off)}
+	}
+	return f, nil
+}
+
+var numberType = reflect.TypeOf(Number(""))
+
+// literalStore decodes a literal stored in item into v.
+//
+// fromQuoted indicates whether this literal came from unwrapping a
+// string from the ",string" struct tag option. this is used only to
+// produce more helpful error messages.
+func (d *decodeState) literalStore(item []byte, v reflect.Value, fromQuoted bool) {
+	// Check for unmarshaler.
+	if len(item) == 0 {
+		//Empty string given
+		d.saveError(fmt.Errorf("json: invalid use of ,string struct tag, trying to unmarshal %q into %v", item, v.Type()))
+		return
+	}
+	wantptr := item[0] == 'n' // null
+	u, ut, pv := d.indirect(v, wantptr)
+	if u != nil {
+		err := u.UnmarshalJSON(item)
+		if err != nil {
+			d.error(err)
+		}
+		return
+	}
+	if ut != nil {
+		if item[0] != '"' {
+			if fromQuoted {
+				d.saveError(fmt.Errorf("json: invalid use of ,string struct tag, trying to unmarshal %q into %v", item, v.Type()))
+			} else {
+				d.saveError(&UnmarshalTypeError{"string", v.Type(), int64(d.off)})
+			}
+			return
+		}
+		s, ok := unquoteBytes(item)
+		if !ok {
+			if fromQuoted {
+				d.error(fmt.Errorf("json: invalid use of ,string struct tag, trying to unmarshal %q into %v", item, v.Type()))
+			} else {
+				d.error(errPhase)
+			}
+		}
+		err := ut.UnmarshalText(s)
+		if err != nil {
+			d.error(err)
+		}
+		return
+	}
+
+	v = pv
+
+	switch c := item[0]; c {
+	case 'n': // null
+		switch v.Kind() {
+		case reflect.Interface, reflect.Ptr, reflect.Map, reflect.Slice:
+			v.Set(reflect.Zero(v.Type()))
+			// otherwise, ignore null for primitives/string
+		}
+	case 't', 'f': // true, false
+		value := c == 't'
+		switch v.Kind() {
+		default:
+			if fromQuoted {
+				d.saveError(fmt.Errorf("json: invalid use of ,string struct tag, trying to unmarshal %q into %v", item, v.Type()))
+			} else {
+				d.saveError(&UnmarshalTypeError{"bool", v.Type(), int64(d.off)})
+			}
+		case reflect.Bool:
+			v.SetBool(value)
+		case reflect.Interface:
+			if v.NumMethod() == 0 {
+				v.Set(reflect.ValueOf(value))
+			} else {
+				d.saveError(&UnmarshalTypeError{"bool", v.Type(), int64(d.off)})
+			}
+		}
+
+	case '"': // string
+		s, ok := unquoteBytes(item)
+		if !ok {
+			if fromQuoted {
+				d.error(fmt.Errorf("json: invalid use of ,string struct tag, trying to unmarshal %q into %v", item, v.Type()))
+			} else {
+				d.error(errPhase)
+			}
+		}
+		switch v.Kind() {
+		default:
+			d.saveError(&UnmarshalTypeError{"string", v.Type(), int64(d.off)})
+		case reflect.Slice:
+			if v.Type().Elem().Kind() != reflect.Uint8 {
+				d.saveError(&UnmarshalTypeError{"string", v.Type(), int64(d.off)})
+				break
+			}
+			b := make([]byte, base64.StdEncoding.DecodedLen(len(s)))
+			n, err := base64.StdEncoding.Decode(b, s)
+			if err != nil {
+				d.saveError(err)
+				break
+			}
+			v.SetBytes(b[:n])
+		case reflect.String:
+			v.SetString(string(s))
+		case reflect.Interface:
+			if v.NumMethod() == 0 {
+				v.Set(reflect.ValueOf(string(s)))
+			} else {
+				d.saveError(&UnmarshalTypeError{"string", v.Type(), int64(d.off)})
+			}
+		}
+
+	default: // number
+		if c != '-' && (c < '0' || c > '9') {
+			if fromQuoted {
+				d.error(fmt.Errorf("json: invalid use of ,string struct tag, trying to unmarshal %q into %v", item, v.Type()))
+			} else {
+				d.error(errPhase)
+			}
+		}
+		s := string(item)
+		switch v.Kind() {
+		default:
+			if v.Kind() == reflect.String && v.Type() == numberType {
+				v.SetString(s)
+				if !isValidNumber(s) {
+					d.error(fmt.Errorf("json: invalid number literal, trying to unmarshal %q into Number", item))
+				}
+				break
+			}
+			if fromQuoted {
+				d.error(fmt.Errorf("json: invalid use of ,string struct tag, trying to unmarshal %q into %v", item, v.Type()))
+			} else {
+				d.error(&UnmarshalTypeError{"number", v.Type(), int64(d.off)})
+			}
+		case reflect.Interface:
+			n, err := d.convertNumber(s)
+			if err != nil {
+				d.saveError(err)
+				break
+			}
+			if v.NumMethod() != 0 {
+				d.saveError(&UnmarshalTypeError{"number", v.Type(), int64(d.off)})
+				break
+			}
+			v.Set(reflect.ValueOf(n))
+
+		case reflect.Int, reflect.Int8, reflect.Int16, reflect.Int32, reflect.Int64:
+			n, err := strconv.ParseInt(s, 10, 64)
+			if err != nil || v.OverflowInt(n) {
+				d.saveError(&UnmarshalTypeError{"number " + s, v.Type(), int64(d.off)})
+				break
+			}
+			v.SetInt(n)
+
+		case reflect.Uint, reflect.Uint8, reflect.Uint16, reflect.Uint32, reflect.Uint64, reflect.Uintptr:
+			n, err := strconv.ParseUint(s, 10, 64)
+			if err != nil || v.OverflowUint(n) {
+				d.saveError(&UnmarshalTypeError{"number " + s, v.Type(), int64(d.off)})
+				break
+			}
+			v.SetUint(n)
+
+		case reflect.Float32, reflect.Float64:
+			n, err := strconv.ParseFloat(s, v.Type().Bits())
+			if err != nil || v.OverflowFloat(n) {
+				d.saveError(&UnmarshalTypeError{"number " + s, v.Type(), int64(d.off)})
+				break
+			}
+			v.SetFloat(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)
+		panic("unreachable")
+	case scanBeginArray:
+		return d.arrayInterface()
+	case scanBeginObject:
+		return d.objectInterface()
+	case scanBeginLiteral:
+		return d.literalInterface()
+	case scanBeginName:
+		return d.nameInterface()
+	}
+}
+
+func (d *decodeState) syntaxError(expected string) {
+	msg := fmt.Sprintf("invalid character '%c' looking for %s", d.data[d.off-1], expected)
+	d.error(&SyntaxError{msg, int64(d.off)})
+}
+
+// arrayInterface is like array but returns []interface{}.
+func (d *decodeState) arrayInterface() []interface{} {
+	var v = make([]interface{}, 0)
+	for {
+		// Look ahead for ] - can only happen on first iteration.
+		op := d.scanWhile(scanSkipSpace)
+		if op == scanEndArray {
+			if len(v) > 0 && !d.ext.trailingCommas {
+				d.syntaxError("beginning of value")
+			}
+			break
+		}
+
+		// Back up so d.value can have the byte we just read.
+		d.off--
+		d.scan.undo(op)
+
+		v = append(v, 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() interface{} {
+	v, ok := d.keyed()
+	if ok {
+		return v
+	}
+
+	m := make(map[string]interface{})
+	for {
+		// Read opening " of string key or closing }.
+		op := d.scanWhile(scanSkipSpace)
+		if op == scanEndObject {
+			if len(m) > 0 && !d.ext.trailingCommas {
+				d.syntaxError("beginning of object key string")
+			}
+			break
+		}
+		if op == scanBeginName {
+			if !d.ext.unquotedKeys {
+				d.syntaxError("beginning of object key string")
+			}
+		} else if op != scanBeginLiteral {
+			d.error(errPhase)
+		}
+		unquotedKey := op == scanBeginName
+
+		// Read string key.
+		start := d.off - 1
+		op = d.scanWhile(scanContinue)
+		item := d.data[start : d.off-1]
+		var key string
+		if unquotedKey {
+			key = string(item)
+		} else {
+			var ok bool
+			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 := d.convertNumber(string(item))
+		if err != nil {
+			d.saveError(err)
+		}
+		return n
+	}
+}
+
+// nameInterface is like function but returns map[string]interface{}.
+func (d *decodeState) nameInterface() interface{} {
+	v, ok := d.keyed()
+	if ok {
+		return v
+	}
+
+	nameStart := d.off - 1
+
+	op := d.scanWhile(scanContinue)
+
+	name := d.data[nameStart : d.off-1]
+	if op != scanParam {
+		// Back up so the byte just read is consumed next.
+		d.off--
+		d.scan.undo(op)
+		if l, ok := d.convertLiteral(name); ok {
+			return l
+		}
+		d.error(&SyntaxError{fmt.Sprintf("json: unknown constant %q", name), int64(d.off)})
+	}
+
+	funcName := string(name)
+	funcData := d.ext.funcs[funcName]
+	if funcData.key == "" {
+		d.error(fmt.Errorf("json: unknown function %q", funcName))
+	}
+
+	m := make(map[string]interface{})
+	for i := 0; ; i++ {
+		// Look ahead for ) - can only happen on first iteration.
+		op := d.scanWhile(scanSkipSpace)
+		if op == scanEndParams {
+			break
+		}
+
+		// Back up so d.value can have the byte we just read.
+		d.off--
+		d.scan.undo(op)
+
+		if i >= len(funcData.args) {
+			d.error(fmt.Errorf("json: too many arguments for function %s", funcName))
+		}
+		m[funcData.args[i]] = d.valueInterface()
+
+		// Next token must be , or ).
+		op = d.scanWhile(scanSkipSpace)
+		if op == scanEndParams {
+			break
+		}
+		if op != scanParam {
+			d.error(errPhase)
+		}
+	}
+	return map[string]interface{}{funcData.key: m}
+}
+
+// getu4 decodes \uXXXX from the beginning of s, returning the hex value,
+// or it returns -1.
+func getu4(s []byte) rune {
+	if len(s) < 6 || s[0] != '\\' || s[1] != 'u' {
+		return -1
+	}
+	r, err := strconv.ParseUint(string(s[2:6]), 16, 64)
+	if err != nil {
+		return -1
+	}
+	return rune(r)
+}
+
+// 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) {
+	s, ok = unquoteBytes(s)
+	t = string(s)
+	return
+}
+
+func unquoteBytes(s []byte) (t []byte, ok bool) {
+	if len(s) < 2 || s[0] != '"' || s[len(s)-1] != '"' {
+		return
+	}
+	s = s[1 : len(s)-1]
+
+	// Check for unusual characters. If there are none,
+	// then no unquoting is needed, so return a slice of the
+	// original bytes.
+	r := 0
+	for r < len(s) {
+		c := s[r]
+		if c == '\\' || c == '"' || c < ' ' {
+			break
+		}
+		if c < utf8.RuneSelf {
+			r++
+			continue
+		}
+		rr, size := utf8.DecodeRune(s[r:])
+		if rr == utf8.RuneError && size == 1 {
+			break
+		}
+		r += size
+	}
+	if r == len(s) {
+		return s, true
+	}
+
+	b := make([]byte, len(s)+2*utf8.UTFMax)
+	w := copy(b, s[0:r])
+	for r < len(s) {
+		// 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) {
+				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--
+				rr := getu4(s[r:])
+				if rr < 0 {
+					return
+				}
+				r += 6
+				if utf16.IsSurrogate(rr) {
+					rr1 := getu4(s[r:])
+					if dec := utf16.DecodeRune(rr, rr1); dec != unicode.ReplacementChar {
+						// A valid pair; consume.
+						r += 6
+						w += utf8.EncodeRune(b[w:], dec)
+						break
+					}
+					// Invalid surrogate; fall back to replacement rune.
+					rr = unicode.ReplacementChar
+				}
+				w += utf8.EncodeRune(b[w:], rr)
+			}
+
+		// 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:
+			rr, size := utf8.DecodeRune(s[r:])
+			r += size
+			w += utf8.EncodeRune(b[w:], rr)
+		}
+	}
+	return b[0:w], true
+}