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-rw-r--r--src/pkg/json/parse.go419
1 files changed, 419 insertions, 0 deletions
diff --git a/src/pkg/json/parse.go b/src/pkg/json/parse.go
new file mode 100644
index 000000000..e33b9dbc1
--- /dev/null
+++ b/src/pkg/json/parse.go
@@ -0,0 +1,419 @@
+// Copyright 2009 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.
+
+// JSON (JavaScript Object Notation) parser.
+// See http://www.json.org/
+
+// The json package implements a simple parser and
+// representation for JSON (JavaScript Object Notation),
+// as defined at http://www.json.org/.
+package json
+
+import (
+ "fmt";
+ "io";
+ "math";
+ "strconv";
+ "strings";
+ "utf8";
+)
+
+// Strings
+//
+// Double quoted with escapes: \" \\ \/ \b \f \n \r \t \uXXXX.
+// No literal control characters, supposedly.
+// Have also seen \' and embedded newlines.
+
+func _UnHex(p string, r, l int) (v int, ok bool) {
+ v = 0;
+ for i := r; i < l; i++ {
+ if i >= len(p) {
+ return 0, false
+ }
+ v *= 16;
+ switch {
+ case '0' <= p[i] && p[i] <= '9':
+ v += int(p[i] - '0');
+ case 'a' <= p[i] && p[i] <= 'f':
+ v += int(p[i] - 'a' + 10);
+ case 'A' <= p[i] && p[i] <= 'F':
+ v += int(p[i] - 'A' + 10);
+ default:
+ return 0, false;
+ }
+ }
+ return v, true;
+}
+
+// Unquote unquotes the JSON-quoted string s,
+// returning a raw string t. If s is not a valid
+// JSON-quoted string, Unquote returns with ok set to false.
+func Unquote(s string) (t string, ok bool) {
+ if len(s) < 2 || s[0] != '"' || s[len(s)-1] != '"' {
+ return
+ }
+ b := make([]byte, len(s));
+ w := 0;
+ for r := 1; r < len(s)-1; {
+ switch {
+ case s[r] == '\\':
+ 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, ok := _UnHex(s, r, 4);
+ if !ok {
+ return
+ }
+ r += 4;
+ w += utf8.EncodeRune(rune, b[w:len(b)]);
+ }
+ // Control characters are invalid, but we've seen raw \n.
+ case s[r] < ' ' && s[r] != '\n':
+ if s[r] == '\n' {
+ b[w] = '\n';
+ r++;
+ w++;
+ break;
+ }
+ return;
+ // ASCII
+ case s[r] < utf8.RuneSelf:
+ b[w] = s[r];
+ r++;
+ w++;
+ // Coerce to well-formed UTF-8.
+ default:
+ rune, size := utf8.DecodeRuneInString(s[r:len(s)]);
+ r += size;
+ w += utf8.EncodeRune(rune, b[w:len(b)]);
+ }
+ }
+ return string(b[0:w]), true
+}
+
+// Quote quotes the raw string s using JSON syntax,
+// so that Unquote(Quote(s)) = s, true.
+func Quote(s string) string {
+ chr := make([]byte, utf8.UTFMax);
+ chr0 := chr[0:1];
+ b := new(io.ByteBuffer);
+ chr[0] = '"';
+ b.Write(chr0);
+ for i := 0; i < len(s); i++ {
+ switch {
+ case s[i]=='"' || s[i]=='\\':
+ chr[0] = '\\';
+ chr[1] = s[i];
+ b.Write(chr[0:2]);
+
+ case s[i] == '\b':
+ chr[0] = '\\';
+ chr[1] = 'b';
+ b.Write(chr[0:2]);
+
+ case s[i] == '\f':
+ chr[0] = '\\';
+ chr[1] = 'f';
+ b.Write(chr[0:2]);
+
+ case s[i] == '\n':
+ chr[0] = '\\';
+ chr[1] = 'n';
+ b.Write(chr[0:2]);
+
+ case s[i] == '\r':
+ chr[0] = '\\';
+ chr[1] = 'r';
+ b.Write(chr[0:2]);
+
+ case s[i] == '\t':
+ chr[0] = '\\';
+ chr[1] = 't';
+ b.Write(chr[0:2]);
+
+ case 0x20 <= s[i] && s[i] < utf8.RuneSelf:
+ chr[0] = s[i];
+ b.Write(chr0);
+ }
+ }
+ chr[0] = '"';
+ b.Write(chr0);
+ return string(b.Data());
+}
+
+
+// _Lexer
+
+type _Lexer struct {
+ s string;
+ i int;
+ kind int;
+ token string;
+}
+
+func punct(c byte) bool {
+ return c=='"' || c=='[' || c==']' || c==':' || c=='{' || c=='}' || c==','
+}
+
+func white(c byte) bool {
+ return c==' ' || c=='\t' || c=='\n' || c=='\v'
+}
+
+func skipwhite(p string, i int) int {
+ for i < len(p) && white(p[i]) {
+ i++
+ }
+ return i
+}
+
+func skiptoken(p string, i int) int {
+ for i < len(p) && !punct(p[i]) && !white(p[i]) {
+ i++
+ }
+ return i
+}
+
+func skipstring(p string, i int) int {
+ for i++; i < len(p) && p[i] != '"'; i++ {
+ if p[i] == '\\' {
+ i++
+ }
+ }
+ if i >= len(p) {
+ return i
+ }
+ return i+1
+}
+
+func (t *_Lexer) Next() {
+ i, s := t.i, t.s;
+ i = skipwhite(s, i);
+ if i >= len(s) {
+ t.kind = 0;
+ t.token = "";
+ t.i = len(s);
+ return;
+ }
+
+ c := s[i];
+ switch {
+ case c == '-' || '0' <= c && c <= '9':
+ j := skiptoken(s, i);
+ t.kind = '1';
+ t.token = s[i:j];
+ i = j;
+
+ case 'a' <= c && c <= 'z' || 'A' <= c && c <= 'Z':
+ j := skiptoken(s, i);
+ t.kind = 'a';
+ t.token = s[i:j];
+ i = j;
+
+ case c == '"':
+ j := skipstring(s, i);
+ t.kind = '"';
+ t.token = s[i:j];
+ i = j;
+
+ case c == '[', c == ']', c == ':', c == '{', c == '}', c == ',':
+ t.kind = int(c);
+ t.token = s[i:i+1];
+ i++;
+
+ default:
+ t.kind = '?';
+ t.token = s[i:i+1];
+ }
+
+ t.i = i;
+}
+
+
+// Parser
+//
+// Implements parsing but not the actions. Those are
+// carried out by the implementation of the Builder interface.
+// A Builder represents the object being created.
+// Calling a method like Int64(i) sets that object to i.
+// Calling a method like Elem(i) or Key(s) creates a
+// new builder for a subpiece of the object (logically,
+// an array element or a map key).
+//
+// There are two Builders, in other files.
+// The JsonBuilder builds a generic Json structure
+// in which maps are maps.
+// The StructBuilder copies data into a possibly
+// nested data structure, using the "map keys"
+// as struct field names.
+
+type _Value interface {}
+
+// BUG(rsc): The json Builder interface needs to be
+// reconciled with the xml Builder interface.
+
+// A Builder is an interface implemented by clients and passed
+// to the JSON parser. It gives clients full control over the
+// eventual representation returned by the parser.
+type Builder interface {
+ // Set value
+ Int64(i int64);
+ Uint64(i uint64);
+ Float64(f float64);
+ String(s string);
+ Bool(b bool);
+ Null();
+ Array();
+ Map();
+
+ // Create sub-Builders
+ Elem(i int) Builder;
+ Key(s string) Builder;
+}
+
+func parse(lex *_Lexer, build Builder) bool {
+ ok := false;
+Switch:
+ switch lex.kind {
+ case 0:
+ break;
+ case '1':
+ // If the number is exactly an integer, use that.
+ if i, err := strconv.Atoi64(lex.token); err == nil {
+ build.Int64(i);
+ ok = true;
+ }
+ else if i, err := strconv.Atoui64(lex.token); err == nil {
+ build.Uint64(i);
+ ok = true;
+ }
+ // Fall back to floating point.
+ else if f, err := strconv.Atof64(lex.token); err == nil {
+ build.Float64(f);
+ ok = true;
+ }
+
+ case 'a':
+ switch lex.token {
+ case "true":
+ build.Bool(true);
+ ok = true;
+ case "false":
+ build.Bool(false);
+ ok = true;
+ case "null":
+ build.Null();
+ ok = true;
+ }
+
+ case '"':
+ if str, ok1 := Unquote(lex.token); ok1 {
+ build.String(str);
+ ok = true;
+ }
+
+ case '[':
+ // array
+ build.Array();
+ lex.Next();
+ n := 0;
+ for lex.kind != ']' {
+ if n > 0 {
+ if lex.kind != ',' {
+ break Switch;
+ }
+ lex.Next();
+ }
+ if !parse(lex, build.Elem(n)) {
+ break Switch;
+ }
+ n++;
+ }
+ ok = true;
+
+ case '{':
+ // map
+ lex.Next();
+ build.Map();
+ n := 0;
+ for lex.kind != '}' {
+ if n > 0 {
+ if lex.kind != ',' {
+ break Switch;
+ }
+ lex.Next();
+ }
+ if lex.kind != '"' {
+ break Switch;
+ }
+ key, ok := Unquote(lex.token);
+ if !ok {
+ break Switch;
+ }
+ lex.Next();
+ if lex.kind != ':' {
+ break Switch;
+ }
+ lex.Next();
+ if !parse(lex, build.Key(key)) {
+ break Switch;
+ }
+ n++;
+ }
+ ok = true;
+ }
+
+ if ok {
+ lex.Next();
+ }
+ return ok;
+}
+
+// Parse parses the JSON syntax string s and makes calls to
+// the builder to construct a parsed representation.
+// On success, it returns with ok set to true.
+// On error, it returns with ok set to false, errindx set
+// to the byte index in s where a syntax error occurred,
+// and errtok set to the offending token.
+func Parse(s string, builder Builder) (ok bool, errindx int, errtok string) {
+ lex := new(_Lexer);
+ lex.s = s;
+ lex.Next();
+ if parse(lex, builder) {
+ if lex.kind == 0 { // EOF
+ return true, 0, ""
+ }
+ }
+ return false, lex.i, lex.token
+}
+
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