1 files changed, 79 insertions, 53 deletions

diff --git a/libgo/go/encoding/json/encode.go b/libgo/go/encoding/json/encode.go
index 6bb6de8f079..8f21ddaed94 100644
--- a/libgo/go/encoding/json/encode.go
+++ b/libgo/go/encoding/json/encode.go
@@ -34,7 +34,7 @@ import (
 // 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.
+// its MarshalText method and encodes the result as a JSON string.
 // The nil pointer exception is not strictly necessary
 // but mimics a similar, necessary exception in the behavior of
 // UnmarshalJSON.
@@ -50,25 +50,33 @@ import (
 // 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.
+// This escaping can be disabled using an Encoder that had SetEscapeHTML(false)
+// called on it.
 //
 // 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:
+// Struct values encode as JSON objects.
+// Each exported struct field becomes a member of the object, using the
+// field name as the object key, unless the field is omitted for one of the
+// reasons given below.
 //
-//   // Field is ignored by this package.
-//   Field int `json:"-"`
+// The encoding of each struct field can be customized by the format string
+// stored under the "json" key in the struct field's tag.
+// The format string gives the name of the field, possibly followed by a
+// comma-separated list of options. The name may be empty in order to
+// specify options without overriding the default field name.
+//
+// The "omitempty" option specifies that the field should be omitted
+// from the encoding if the field has an empty value, defined as
+// false, 0, a nil pointer, a nil interface value, and any empty array,
+// slice, map, or string.
+//
+// As a special case, if the field tag is "-", the field is always omitted.
+// Note that a field with name "-" can still be generated using the tag "-,".
+//
+// Examples of struct field tags and their meanings:
 //
 //   // Field appears in JSON as key "myName".
 //   Field int `json:"myName"`
@@ -83,6 +91,12 @@ import (
 //   // Note the leading comma.
 //   Field int `json:",omitempty"`
 //
+//   // Field is ignored by this package.
+//   Field int `json:"-"`
+//
+//   // Field appears in JSON as key "-".
+//   Field int `json:"-,"`
+//
 // 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
@@ -110,7 +124,9 @@ import (
 //
 // 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.
@@ -427,7 +443,11 @@ func marshalerEncoder(e *encodeState, v reflect.Value, opts encOpts) {
 		e.WriteString("null")
 		return
 	}
-	m := v.Interface().(Marshaler)
+	m, ok := v.Interface().(Marshaler)
+	if !ok {
+		e.WriteString("null")
+		return
+	}
 	b, err := m.MarshalJSON()
 	if err == nil {
 		// copy JSON into buffer, checking validity.
@@ -525,7 +545,31 @@ func (bits floatEncoder) encode(e *encodeState, v reflect.Value, opts encOpts) {
 	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))
+
+	// Convert as if by ES6 number to string conversion.
+	// This matches most other JSON generators.
+	// See golang.org/issue/6384 and golang.org/issue/14135.
+	// Like fmt %g, but the exponent cutoffs are different
+	// and exponents themselves are not padded to two digits.
+	b := e.scratch[:0]
+	abs := math.Abs(f)
+	fmt := byte('f')
+	// Note: Must use float32 comparisons for underlying float32 value to get precise cutoffs right.
+	if abs != 0 {
+		if bits == 64 && (abs < 1e-6 || abs >= 1e21) || bits == 32 && (float32(abs) < 1e-6 || float32(abs) >= 1e21) {
+			fmt = 'e'
+		}
+	}
+	b = strconv.AppendFloat(b, f, fmt, -1, int(bits))
+	if fmt == 'e' {
+		// clean up e-09 to e-9
+		n := len(b)
+		if n >= 4 && b[n-4] == 'e' && b[n-3] == '-' && b[n-2] == '0' {
+			b[n-2] = b[n-1]
+			b = b[:n-1]
+		}
+	}
+
 	if opts.quoted {
 		e.WriteByte('"')
 	}
@@ -635,7 +679,7 @@ func (me *mapEncoder) encode(e *encodeState, v reflect.Value, opts encOpts) {
 			e.error(&MarshalerError{v.Type(), err})
 		}
 	}
-	sort.Sort(byString(sv))
+	sort.Slice(sv, func(i, j int) bool { return sv[i].s < sv[j].s })
 
 	for i, kv := range sv {
 		if i > 0 {
@@ -834,15 +878,6 @@ func (w *reflectWithString) resolve() error {
 	panic("unexpected map key type")
 }
 
-// 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()
@@ -850,8 +885,7 @@ func (e *encodeState) string(s string, escapeHTML bool) int {
 	start := 0
 	for i := 0; i < len(s); {
 		if b := s[i]; b < utf8.RuneSelf {
-			if 0x20 <= b && b != '\\' && b != '"' &&
-				(!escapeHTML || b != '<' && b != '>' && b != '&') {
+			if htmlSafeSet[b] || (!escapeHTML && safeSet[b]) {
 				i++
 				continue
 			}
@@ -928,8 +962,7 @@ func (e *encodeState) stringBytes(s []byte, escapeHTML bool) int {
 	start := 0
 	for i := 0; i < len(s); {
 		if b := s[i]; b < utf8.RuneSelf {
-			if 0x20 <= b && b != '\\' && b != '"' &&
-				(!escapeHTML || b != '<' && b != '>' && b != '&') {
+			if htmlSafeSet[b] || (!escapeHTML && safeSet[b]) {
 				i++
 				continue
 			}
@@ -1018,28 +1051,6 @@ func fillField(f field) field {
 	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
 
@@ -1157,7 +1168,22 @@ func typeFields(t reflect.Type) []field {
 		}
 	}
 
-	sort.Sort(byName(fields))
+	sort.Slice(fields, func(i, j int) bool {
+		x := fields
+		// sort field by name, breaking ties with depth, then
+		// breaking ties with "name came from json tag", then
+		// breaking ties with index sequence.
+		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)
+	})
 
 	// Delete all fields that are hidden by the Go rules for embedded fields,
 	// except that fields with JSON tags are promoted.