179 lines
4.3 KiB
Plaintext
179 lines
4.3 KiB
Plaintext
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/* JSON parser based on the grammar described at http://json.org/. */
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{
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/*
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* We can't return |null| in the |value| rule because that would mean parse
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* failure. So we return a special object instead and convert it to |null|
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* later.
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*/
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var null_ = new Object;
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function fixNull(value) {
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return value === null_ ? null : value;
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}
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}
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/* ===== Syntactical Elements ===== */
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start
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= _ object:object { return object; }
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/ _ array:array { return array; }
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object
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= "{" _ "}" _ { return {}; }
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/ "{" _ members:members "}" _ { return members; }
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members
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= ","? head:pair? tail:("," _ pair)* ","? _ {
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var result = {};
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if( head ) { result[head[0]] = fixNull(head[1]); }
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for (var i = 0; i < tail.length; i++) {
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result[tail[i][2][0]] = fixNull(tail[i][2][1]);
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}
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return result;
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}
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pair
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= name:key _ ":" _ value:value { return [name, value]; }
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array
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= "[" _ "]" _ { return []; }
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/ "[" _ elements:elements "]" _ { return elements; }
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elements
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= ","? head:value? tail:("," _ value)* ","? _ {
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var result = [];
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if( typeof head !== 'undefined' && head !== null ) { result.push( fixNull(head) ) }
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for (var i = 0; i < tail.length; i++) {
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result.push(fixNull(tail[i][2]));
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}
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return result;
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}
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value
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= string
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/ single
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/ object
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/ array
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/ "true" _ { return true; }
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/ "false" _ { return false; }
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/ "null" _ { return null_; }
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/ number
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/ lit:literal { return lit.join('').trim() }
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/* ===== Lexical Elements ===== */
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string "double-quote string"
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= '"' '"' _ { return ""; }
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/ '"' chars:chars '"' _ { return chars; }
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single "single-quote string"
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= '\'' '\'' _ { return ""; }
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/ '\'' chars:schars '\'' _ { return chars; }
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chars
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= chars:char+ { return chars.join(""); }
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char
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// In the original JSON grammar: "any-Unicode-character-except-"-or-\-or-control-character"
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= [^"\\\0-\x1F\x7f]
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/ '\\"' { return '"'; }
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/ "\\\\" { return "\\"; }
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/ "\\/" { return "/"; }
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/ "\\b" { return "\b"; }
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/ "\\f" { return "\f"; }
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/ "\\n" { return "\n"; }
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/ "\\r" { return "\r"; }
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/ "\\t" { return "\t"; }
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/ "\\u" h1:hexDigit h2:hexDigit h3:hexDigit h4:hexDigit {
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return String.fromCharCode(parseInt("0x" + h1 + h2 + h3 + h4)); }
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schars
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= chars:schar+ { return chars.join(""); }
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schar
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// In the original JSON grammar: "any-Unicode-character-except-"-or-\-or-control-character"
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= [^'\\\0-\x1F\x7f]
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/ '\\\'' { return '\''; }
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/ "\\\\" { return "\\"; }
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/ "\\/" { return "/"; }
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/ "\\b" { return "\b"; }
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/ "\\f" { return "\f"; }
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/ "\\n" { return "\n"; }
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/ "\\r" { return "\r"; }
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/ "\\t" { return "\t"; }
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/ "\\u" h1:hexDigit h2:hexDigit h3:hexDigit h4:hexDigit {
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return String.fromCharCode(parseInt("0x" + h1 + h2 + h3 + h4)); }
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key "key"
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= string
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/ single
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/ chars:[a-zA-Z0-9_\$\-]+ { return chars.join('') }
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literal
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= lit:litchar+
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litchar
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= [^,}\]]
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number "number"
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= int_:int frac:frac exp:exp _ suffix:litchar*
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{ return 0 === suffix.length ? parseFloat(int_ + frac + exp) : (int_ + frac + exp + suffix.join('')).trim(); }
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/ int_:int frac:frac _ suffix:litchar*
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{ return 0 === suffix.length ? parseFloat(int_ + frac) : (int_ + frac + suffix.join('')).trim(); }
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/ int_:int exp:exp _ suffix:litchar*
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{ return 0 === suffix.length ? parseFloat(int_ + exp) : (int_ + exp + suffix.join('')).trim(); }
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/ int_:int _ suffix:litchar*
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{ return 0 === suffix.length ? parseFloat(int_) : (int_ + suffix.join('')).trim(); }
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int
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= digit19:digit19 digits:digits { return digit19 + digits; }
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/ digit:digit
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/ "-" digit19:digit19 digits:digits { return "-" + digit19 + digits; }
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/ "-" digit:digit { return "-" + digit; }
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frac
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= "." digits:digits { return "." + digits; }
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exp
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= e:e digits:digits { return e + digits; }
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digits
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= digits:digit+ { return digits.join(""); }
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e
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= e:[eE] sign:[+-]? { return e + (sign?sign:''); }
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digit
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= [0-9]
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digit19
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= [1-9]
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hexDigit
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= [0-9a-fA-F]
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/* ===== Whitespace ===== */
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_ "whitespace"
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= whitespace*
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// Whitespace is undefined in the original JSON grammar, so I assume a simple
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// conventional definition consistent with ECMA-262, 5th ed.
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whitespace
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= [ \t\n\r]
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