acorn.js | |
|---|---|
| Acorn is a tiny, fast JavaScript parser written in JavaScript. -Acorn+Acorn was written by Marijn Haverbeke and released under an MIT +license. The Unicode regexps (for identifiers and whitespace) were +taken from Esprima by Ariya Hidayat. -(This is a temporary placeholder project page. Better is to come in -the future.) +Git repositories for Acorn are available at -Acorn is a tiny, fast JavaScript parser written in JavaScript. If
-defines The output conforms largely to
-the Mozilla
-parser API with the caveat that non-ECMAscript features
-( Please use the github bug tracker to report issues. | (function(exports) {
+ "strict mode";
- |
| The main exported interface (under | var options, input, inputLen;
- |
| A second optional argument can be given to further configure +the parser process. These options are recognized: | var defaultOptions = exports.defaultOptions = { |
|
| ecmaVersion: 5, |
| Turn on | strictSemicolons: false, |
| When | allowTrailingCommas: true, |
| By default, reserved words are not enforced. Enable
+ | forbidReserved: false, |
| When | trackComments: false, |
| By default, the | linePositions: false
+ }; |
| The | var getLineInfo = exports.getLineInfo = function(input, offset) {
+ for (var line = 1, cur = 0;;) {
+ lineBreak.lastIndex = cur;
+ var match = lineBreak.exec(input);
+ if (match && match.index < offset) {
+ ++line;
+ cur = match.index + match[0].length;
+ } else break;
+ }
+ return {line: line, column: offset - cur};
+ }; |
| Acorn is organized as a tokenizer and a recursive-descent parser.
+Both use (closure-)global variables to keep their state and
+communicate. We already saw the | |
| The current position of the tokenizer in the input. | var tokPos; |
| The start and end positions of the current token. These hold
+integers when | var tokStart, tokEnd; |
| The type and value of the current token. Token types are objects,
+named by variables against which they can be compared, and
+holding properties that describe them (indicating, for example,
+the precedence of an infix operator, and the original name of a
+keyword token). The kind of value that's held in | var tokType, tokVal; |
| These are used to hold arrays of comments when
+ | var tokCommentsBefore, tokCommentsAfter; |
| Interal state for the tokenizer. To distinguish between division
+operators and regular expressions, it remembers whether the last
+token was one that is allowed to be followed by an expression.
+(If it is, a slash is probably a regexp, if it isn't it's a
+division operator. See the | var tokRegexpAllowed, tokComments; |
| When | var tokCurLine, tokLineStart, tokLineStartNext; |
| These store the position of the previous token, which is useful
+when finishing a node and assigning its | var lastStart, lastEnd; |
| This is the parser's state. | var inFunction, labels, strict; |
| This function is used to raise exceptions on parse errors. It
+takes either a | function raise(pos, message) {
+ if (typeof pos == "number") pos = getLineInfo(input, pos);
+ message += " (" + pos.line + ":" + pos.column + ")";
+ throw new SyntaxError(message);
+ } |
Token types | |
| The assignment of fine-grained, information-carrying type objects +allows the tokenizer to store the information it has about a +token in a way that is very cheap for the parser to look up. | |
| All token type variables start with an underscore, to make them +easy to recognize. | |
| These are the general types. The | var _num = {type: "num"}, _regexp = {type: "regexp"}, _string = {type: "string"};
+ var _name = {type: "name"}, _eof = {type: "eof"}; |
| Keyword tokens. The The
| var _break = {keyword: "break"}, _case = {keyword: "case", beforeExpr: true}, _catch = {keyword: "catch"};
+ var _continue = {keyword: "continue"}, _debugger = {keyword: "debugger"}, _default = {keyword: "default"};
+ var _do = {keyword: "do", isLoop: true}, _else = {keyword: "else", beforeExpr: true};
+ var _finally = {keyword: "finally"}, _for = {keyword: "for", isLoop: true}, _function = {keyword: "function"};
+ var _if = {keyword: "if"}, _return = {keyword: "return", beforeExpr: true}, _switch = {keyword: "switch"};
+ var _throw = {keyword: "throw", beforeExpr: true}, _try = {keyword: "try"}, _var = {keyword: "var"};
+ var _while = {keyword: "while", isLoop: true}, _with = {keyword: "with"}, _new = {keyword: "new", beforeExpr: true}; |
| The keywords that denote values. | var _null = {keyword: "null", atomValue: null}, _true = {keyword: "true", atomValue: true};
+ var _false = {keyword: "false", atomValue: false}; |
| Some keywords are treated as regular operators. | var _in = {keyword: "in", binop: 7, beforeExpr: true}; |
| Map keyword names to token types. | var keywordTypes = {"break": _break, "case": _case, "catch": _catch,
+ "continue": _continue, "debugger": _debugger, "default": _default,
+ "do": _do, "else": _else, "finally": _finally, "for": _for,
+ "function": _function, "if": _if, "return": _return, "switch": _switch,
+ "throw": _throw, "try": _try, "var": _var, "while": _while, "with": _with,
+ "null": _null, "true": _true, "false": _false, "new": _new, "in": _in,
+ "instanceof": {keyword: "instanceof", binop: 7},
+ "typeof": {keyword: "typeof", prefix: true},
+ "void": {keyword: "void", prefix: true},
+ "delete": {keyword: "delete", prefix: true}}; |
| Punctuation token types. Again, the | var _bracketL = {type: "[", beforeExpr: true}, _bracketR = {type: "]"}, _braceL = {type: "{", beforeExpr: true};
+ var _braceR = {type: "}"}, _parenL = {type: "(", beforeExpr: true}, _parenR = {type: ")"};
+ var _comma = {type: ",", beforeExpr: true}, _semi = {type: ";", beforeExpr: true};
+ var _colon = {type: ":", beforeExpr: true}, _dot = {type: "."}, _question = {type: "?", beforeExpr: true}; |
| Operators. These carry several kinds of properties to help the +parser use them properly (the presence of these properties is +what categorizes them as operators). + +
| var _slash = {binop: 10, beforeExpr: true}, _eq = {isAssign: true, beforeExpr: true};
+ var _assign = {isAssign: true, beforeExpr: true}, _plusmin = {binop: 9, prefix: true, beforeExpr: true};
+ var _incdec = {postfix: true, prefix: true, isUpdate: true}, _prefix = {prefix: true, beforeExpr: true};
+ var _bin1 = {binop: 1, beforeExpr: true}, _bin2 = {binop: 2, beforeExpr: true};
+ var _bin3 = {binop: 3, beforeExpr: true}, _bin4 = {binop: 4, beforeExpr: true};
+ var _bin5 = {binop: 5, beforeExpr: true}, _bin6 = {binop: 6, beforeExpr: true};
+ var _bin7 = {binop: 7, beforeExpr: true}, _bin8 = {binop: 8, beforeExpr: true};
+ var _bin10 = {binop: 10, beforeExpr: true}; |
| This is a trick taken from Esprima. It turns out that, on
+non-Chrome browsers, to check whether a string is in a set, a
+predicate containing a big ugly It starts by sorting the words by length. | function makePredicate(words) {
+ words = words.split(" ");
+ var f = "(function(str){", cats = [];
+ out: for (var i = 0; i < words.length; ++i) {
+ for (var j = 0; j < cats.length; ++j)
+ if (cats[j][0].length == words[i].length) {
+ cats[j].push(words[i]);
+ continue out;
+ }
+ cats.push([words[i]]);
+ }
+ function compareTo(arr) {
+ if (arr.length == 1) return f += "return str === " + JSON.stringify(arr[0]) + ";";
+ f += "switch(str){";
+ for (var i = 0; i < arr.length; ++i) f += "case " + JSON.stringify(arr[i]) + ":";
+ f += "return true}return false;";
+ } |
| When there are more than three length categories, an outer +switch first dispatches on the lengths, to save on comparisons. | if (cats.length > 3) {
+ cats.sort(function(a, b) {return b.length - a.length;});
+ f += "switch(str.length){";
+ for (var i = 0; i < cats.length; ++i) {
+ var cat = cats[i];
+ f += "case " + cat[0].length + ":";
+ compareTo(cat);
+ }
+ f += "}"; |
| Otherwise, simply generate a flat | } else {
+ compareTo(words);
+ }
+ return (1, eval)(f + "})");
+ } |
| The ECMAScript 3 reserved word list. | var isReservedWord3 = makePredicate("abstract boolean byte char class double enum export extends final float goto implements import int interface long native package private protected public short static super synchronized throws transient volatile"); |
| ECMAScript 5 reserved words. | var isReservedWord5 = makePredicate("class enum extends super const export import"); |
| The additional reserved words in strict mode. | var isStrictReservedWord = makePredicate("implements interface let package private protected public static yield"); |
| The forbidden variable names in strict mode. | var isStrictBadIdWord = makePredicate("eval arguments"); |
| And the keywords. | var isKeyword = makePredicate("break case catch continue debugger default do else finally for function if return switch throw try var while with null true false instanceof typeof void delete new in"); |
Character categories | |
| Big ugly regular expressions that match characters in the +whitespace, identifier, and identifier-start categories. These +are only applied when a character is found to actually have a +code point above 128. | var nonASCIIwhitespace = /[\u1680\u180E\u2000-\u200A\u202F\u205F\u3000\uFEFF]/;
+ var nonASCIIidentifierStartChars = "\xaa\xb5\xba\xc0-\xd6\xd8-\xf6\xf8-\u02c1\u02c6-\u02d1\u02e0-\u02e4\u02ec\u02ee\u0370-\u0374\u0376\u0377\u037a-\u037d\u0386\u0388-\u038a\u038c\u038e-\u03a1\u03a3-\u03f5\u03f7-\u0481\u048a-\u0527\u0531-\u0556\u0559\u0561-\u0587\u05d0-\u05ea\u05f0-\u05f2\u0620-\u064a\u066e\u066f\u0671-\u06d3\u06d5\u06e5\u06e6\u06ee\u06ef\u06fa-\u06fc\u06ff\u0710\u0712-\u072f\u074d-\u07a5\u07b1\u07ca-\u07ea\u07f4\u07f5\u07fa\u0800-\u0815\u081a\u0824\u0828\u0840-\u0858\u08a0\u08a2-\u08ac\u0904-\u0939\u093d\u0950\u0958-\u0961\u0971-\u0977\u0979-\u097f\u0985-\u098c\u098f\u0990\u0993-\u09a8\u09aa-\u09b0\u09b2\u09b6-\u09b9\u09bd\u09ce\u09dc\u09dd\u09df-\u09e1\u09f0\u09f1\u0a05-\u0a0a\u0a0f\u0a10\u0a13-\u0a28\u0a2a-\u0a30\u0a32\u0a33\u0a35\u0a36\u0a38\u0a39\u0a59-\u0a5c\u0a5e\u0a72-\u0a74\u0a85-\u0a8d\u0a8f-\u0a91\u0a93-\u0aa8\u0aaa-\u0ab0\u0ab2\u0ab3\u0ab5-\u0ab9\u0abd\u0ad0\u0ae0\u0ae1\u0b05-\u0b0c\u0b0f\u0b10\u0b13-\u0b28\u0b2a-\u0b30\u0b32\u0b33\u0b35-\u0b39\u0b3d\u0b5c\u0b5d\u0b5f-\u0b61\u0b71\u0b83\u0b85-\u0b8a\u0b8e-\u0b90\u0b92-\u0b95\u0b99\u0b9a\u0b9c\u0b9e\u0b9f\u0ba3\u0ba4\u0ba8-\u0baa\u0bae-\u0bb9\u0bd0\u0c05-\u0c0c\u0c0e-\u0c10\u0c12-\u0c28\u0c2a-\u0c33\u0c35-\u0c39\u0c3d\u0c58\u0c59\u0c60\u0c61\u0c85-\u0c8c\u0c8e-\u0c90\u0c92-\u0ca8\u0caa-\u0cb3\u0cb5-\u0cb9\u0cbd\u0cde\u0ce0\u0ce1\u0cf1\u0cf2\u0d05-\u0d0c\u0d0e-\u0d10\u0d12-\u0d3a\u0d3d\u0d4e\u0d60\u0d61\u0d7a-\u0d7f\u0d85-\u0d96\u0d9a-\u0db1\u0db3-\u0dbb\u0dbd\u0dc0-\u0dc6\u0e01-\u0e30\u0e32\u0e33\u0e40-\u0e46\u0e81\u0e82\u0e84\u0e87\u0e88\u0e8a\u0e8d\u0e94-\u0e97\u0e99-\u0e9f\u0ea1-\u0ea3\u0ea5\u0ea7\u0eaa\u0eab\u0ead-\u0eb0\u0eb2\u0eb3\u0ebd\u0ec0-\u0ec4\u0ec6\u0edc-\u0edf\u0f00\u0f40-\u0f47\u0f49-\u0f6c\u0f88-\u0f8c\u1000-\u102a\u103f\u1050-\u1055\u105a-\u105d\u1061\u1065\u1066\u106e-\u1070\u1075-\u1081\u108e\u10a0-\u10c5\u10c7\u10cd\u10d0-\u10fa\u10fc-\u1248\u124a-\u124d\u1250-\u1256\u1258\u125a-\u125d\u1260-\u1288\u128a-\u128d\u1290-\u12b0\u12b2-\u12b5\u12b8-\u12be\u12c0\u12c2-\u12c5\u12c8-\u12d6\u12d8-\u1310\u1312-\u1315\u1318-\u135a\u1380-\u138f\u13a0-\u13f4\u1401-\u166c\u166f-\u167f\u1681-\u169a\u16a0-\u16ea\u16ee-\u16f0\u1700-\u170c\u170e-\u1711\u1720-\u1731\u1740-\u1751\u1760-\u176c\u176e-\u1770\u1780-\u17b3\u17d7\u17dc\u1820-\u1877\u1880-\u18a8\u18aa\u18b0-\u18f5\u1900-\u191c\u1950-\u196d\u1970-\u1974\u1980-\u19ab\u19c1-\u19c7\u1a00-\u1a16\u1a20-\u1a54\u1aa7\u1b05-\u1b33\u1b45-\u1b4b\u1b83-\u1ba0\u1bae\u1baf\u1bba-\u1be5\u1c00-\u1c23\u1c4d-\u1c4f\u1c5a-\u1c7d\u1ce9-\u1cec\u1cee-\u1cf1\u1cf5\u1cf6\u1d00-\u1dbf\u1e00-\u1f15\u1f18-\u1f1d\u1f20-\u1f45\u1f48-\u1f4d\u1f50-\u1f57\u1f59\u1f5b\u1f5d\u1f5f-\u1f7d\u1f80-\u1fb4\u1fb6-\u1fbc\u1fbe\u1fc2-\u1fc4\u1fc6-\u1fcc\u1fd0-\u1fd3\u1fd6-\u1fdb\u1fe0-\u1fec\u1ff2-\u1ff4\u1ff6-\u1ffc\u2071\u207f\u2090-\u209c\u2102\u2107\u210a-\u2113\u2115\u2119-\u211d\u2124\u2126\u2128\u212a-\u212d\u212f-\u2139\u213c-\u213f\u2145-\u2149\u214e\u2160-\u2188\u2c00-\u2c2e\u2c30-\u2c5e\u2c60-\u2ce4\u2ceb-\u2cee\u2cf2\u2cf3\u2d00-\u2d25\u2d27\u2d2d\u2d30-\u2d67\u2d6f\u2d80-\u2d96\u2da0-\u2da6\u2da8-\u2dae\u2db0-\u2db6\u2db8-\u2dbe\u2dc0-\u2dc6\u2dc8-\u2dce\u2dd0-\u2dd6\u2dd8-\u2dde\u2e2f\u3005-\u3007\u3021-\u3029\u3031-\u3035\u3038-\u303c\u3041-\u3096\u309d-\u309f\u30a1-\u30fa\u30fc-\u30ff\u3105-\u312d\u3131-\u318e\u31a0-\u31ba\u31f0-\u31ff\u3400-\u4db5\u4e00-\u9fcc\ua000-\ua48c\ua4d0-\ua4fd\ua500-\ua60c\ua610-\ua61f\ua62a\ua62b\ua640-\ua66e\ua67f-\ua697\ua6a0-\ua6ef\ua717-\ua71f\ua722-\ua788\ua78b-\ua78e\ua790-\ua793\ua7a0-\ua7aa\ua7f8-\ua801\ua803-\ua805\ua807-\ua80a\ua80c-\ua822\ua840-\ua873\ua882-\ua8b3\ua8f2-\ua8f7\ua8fb\ua90a-\ua925\ua930-\ua946\ua960-\ua97c\ua984-\ua9b2\ua9cf\uaa00-\uaa28\uaa40-\uaa42\uaa44-\uaa4b\uaa60-\uaa76\uaa7a\uaa80-\uaaaf\uaab1\uaab5\uaab6\uaab9-\uaabd\uaac0\uaac2\uaadb-\uaadd\uaae0-\uaaea\uaaf2-\uaaf4\uab01-\uab06\uab09-\uab0e\uab11-\uab16\uab20-\uab26\uab28-\uab2e\uabc0-\uabe2\uac00-\ud7a3\ud7b0-\ud7c6\ud7cb-\ud7fb\uf900-\ufa6d\ufa70-\ufad9\ufb00-\ufb06\ufb13-\ufb17\ufb1d\ufb1f-\ufb28\ufb2a-\ufb36\ufb38-\ufb3c\ufb3e\ufb40\ufb41\ufb43\ufb44\ufb46-\ufbb1\ufbd3-\ufd3d\ufd50-\ufd8f\ufd92-\ufdc7\ufdf0-\ufdfb\ufe70-\ufe74\ufe76-\ufefc\uff21-\uff3a\uff41-\uff5a\uff66-\uffbe\uffc2-\uffc7\uffca-\uffcf\uffd2-\uffd7\uffda-\uffdc";
+ var nonASCIIidentifierChars = "\u0371-\u0374\u0483-\u0487\u0591-\u05bd\u05bf\u05c1\u05c2\u05c4\u05c5\u05c7\u0610-\u061a\u0620-\u0649\u0672-\u06d3\u06e7-\u06e8\u06fb-\u06fc\u0730-\u074a\u0800-\u0814\u081b-\u0823\u0825-\u0827\u0829-\u082d\u0840-\u0857\u08e4-\u08fe\u0900-\u0903\u093a-\u093c\u093e-\u094f\u0951-\u0957\u0962-\u0963\u0966-\u096f\u0981-\u0983\u09bc\u09be-\u09c4\u09c7\u09c8\u09d7\u09df-\u09e0\u0a01-\u0a03\u0a3c\u0a3e-\u0a42\u0a47\u0a48\u0a4b-\u0a4d\u0a51\u0a66-\u0a71\u0a75\u0a81-\u0a83\u0abc\u0abe-\u0ac5\u0ac7-\u0ac9\u0acb-\u0acd\u0ae2-\u0ae3\u0ae6-\u0aef\u0b01-\u0b03\u0b3c\u0b3e-\u0b44\u0b47\u0b48\u0b4b-\u0b4d\u0b56\u0b57\u0b5f-\u0b60\u0b66-\u0b6f\u0b82\u0bbe-\u0bc2\u0bc6-\u0bc8\u0bca-\u0bcd\u0bd7\u0be6-\u0bef\u0c01-\u0c03\u0c46-\u0c48\u0c4a-\u0c4d\u0c55\u0c56\u0c62-\u0c63\u0c66-\u0c6f\u0c82\u0c83\u0cbc\u0cbe-\u0cc4\u0cc6-\u0cc8\u0cca-\u0ccd\u0cd5\u0cd6\u0ce2-\u0ce3\u0ce6-\u0cef\u0d02\u0d03\u0d46-\u0d48\u0d57\u0d62-\u0d63\u0d66-\u0d6f\u0d82\u0d83\u0dca\u0dcf-\u0dd4\u0dd6\u0dd8-\u0ddf\u0df2\u0df3\u0e34-\u0e3a\u0e40-\u0e45\u0e50-\u0e59\u0eb4-\u0eb9\u0ec8-\u0ecd\u0ed0-\u0ed9\u0f18\u0f19\u0f20-\u0f29\u0f35\u0f37\u0f39\u0f41-\u0f47\u0f71-\u0f84\u0f86-\u0f87\u0f8d-\u0f97\u0f99-\u0fbc\u0fc6\u1000-\u1029\u1040-\u1049\u1067-\u106d\u1071-\u1074\u1082-\u108d\u108f-\u109d\u135d-\u135f\u170e-\u1710\u1720-\u1730\u1740-\u1750\u1772\u1773\u1780-\u17b2\u17dd\u17e0-\u17e9\u180b-\u180d\u1810-\u1819\u1920-\u192b\u1930-\u193b\u1951-\u196d\u19b0-\u19c0\u19c8-\u19c9\u19d0-\u19d9\u1a00-\u1a15\u1a20-\u1a53\u1a60-\u1a7c\u1a7f-\u1a89\u1a90-\u1a99\u1b46-\u1b4b\u1b50-\u1b59\u1b6b-\u1b73\u1bb0-\u1bb9\u1be6-\u1bf3\u1c00-\u1c22\u1c40-\u1c49\u1c5b-\u1c7d\u1cd0-\u1cd2\u1d00-\u1dbe\u1e01-\u1f15\u200c\u200d\u203f\u2040\u2054\u20d0-\u20dc\u20e1\u20e5-\u20f0\u2d81-\u2d96\u2de0-\u2dff\u3021-\u3028\u3099\u309a\ua640-\ua66d\ua674-\ua67d\ua69f\ua6f0-\ua6f1\ua7f8-\ua800\ua806\ua80b\ua823-\ua827\ua880-\ua881\ua8b4-\ua8c4\ua8d0-\ua8d9\ua8f3-\ua8f7\ua900-\ua909\ua926-\ua92d\ua930-\ua945\ua980-\ua983\ua9b3-\ua9c0\uaa00-\uaa27\uaa40-\uaa41\uaa4c-\uaa4d\uaa50-\uaa59\uaa7b\uaae0-\uaae9\uaaf2-\uaaf3\uabc0-\uabe1\uabec\uabed\uabf0-\uabf9\ufb20-\ufb28\ufe00-\ufe0f\ufe20-\ufe26\ufe33\ufe34\ufe4d-\ufe4f\uff10-\uff19\uff3f";
+ var nonASCIIidentifierStart = new RegExp("[" + nonASCIIidentifierStartChars + "]");
+ var nonASCIIidentifier = new RegExp("[" + nonASCIIidentifierStartChars + nonASCIIidentifierChars + "]"); |
| Whether a single character denotes a newline. | var newline = /[\n\r\u2028\u2029]/; |
| Matches a whole line break (where CRLF is considered a single +line break). Used to count lines. | var lineBreak = /\r\n?|[\n\r\u2028\u2029]/g; |
| Test whether a given character code starts an identifier. | function isIdentifierStart(code) {
+ return (code >= 65 && code <= 90) || (code >= 97 && code <= 122) ||
+ code === 36 || code === 95 ||
+ (code >= 0xaa && nonASCIIidentifierStart.test(String.fromCharCode(code)));
+ } |
| Test whether a given character is part of an identifier. | function isIdentifierChar(ch) {
+ return ((ch >= "a" && ch <= "z") || (ch >= "A" && ch <= "Z") ||
+ (ch >= "0" && ch <= "9") || ch === "$" || ch === "_" ||
+ (ch >= "\xaa" && nonASCIIidentifier.test(ch)));
+ } |
Tokenizer | |
| These are used when | function nextLineStart() {
+ lineBreak.lastIndex = tokLineStart;
+ var match = lineBreak.exec(input);
+ return match ? match.index + match[0].length : input.length + 1;
+ }
+
+ function curLinePos() {
+ while (tokLineStartNext <= tokPos) {
+ ++tokCurLine;
+ tokLineStart = tokLineStartNext;
+ tokLineStartNext = nextLineStart();
+ }
+ return {offset: tokPos, line: tokCurLine, column: tokPos - tokLineStart};
+ } |
| Reset the token state. Used at the start of a parse. | function initTokenState() {
+ tokCurLine = 1;
+ tokPos = tokLineStart = 0;
+ tokLineStartNext = nextLineStart();
+ tokRegexpAllowed = true;
+ tokComments = null;
+ skipSpace();
+ } |
| Called at the end of every token. Sets | function finishToken(type, val) {
+ tokEnd = options.linePositions ? curLinePos() : tokPos;
+ tokType = type;
+ skipSpace();
+ tokVal = val;
+ tokCommentsAfter = tokComments;
+ tokRegexpAllowed = type.beforeExpr;
+ }
+
+ function skipBlockComment() {
+ var end = input.indexOf("*/", tokPos += 2);
+ if (end === -1) raise(tokPos - 2, "Unterminated comment");
+ if (options.trackComments)
+ (tokComments || (tokComments = [])).push(input.slice(tokPos, end));
+ tokPos = end + 2;
+ }
+
+ function skipLineComment() {
+ var start = tokPos;
+ tokPos += 2;
+ while (tokPos < inputLen && !newline.test(input.charAt(tokPos))) ++tokPos;
+ if (options.trackComments)
+ (tokComments || (tokComments = [])).push(input.slice(start, tokPos));
+ } |
| Called at the start of the parse and after every token. Skips
+whitespace and comments, and, if | function skipSpace() {
+ tokComments = null;
+ while (tokPos < inputLen) {
+ var ch = input.charAt(tokPos);
+ if (ch === "/") {
+ var nextCh = input.charAt(tokPos+1);
+ if (nextCh === "*") {
+ skipBlockComment();
+ } else if (nextCh === "/") {
+ skipLineComment();
+ } else break;
+ } else if (ch === " " || ch === '\t' || ch === "\n" || ch === "\r" || ch === "\f" ||
+ ch === "\xa0" || ch === "\x0b" || (ch >= "\u1680" && nonASCIIwhitespace.test(ch))) {
+ ++tokPos;
+ } else {
+ break;
+ }
+ }
+ } |
Token reading | |
| This is the function that is called to fetch the next token. It +is somewhat obscure, because it works in character codes rather +than characters, and because operator parsing has been inlined +into it. + +All in the name of speed. + +The | function readToken(forceRegexp) {
+ tokStart = options.linePositions ? curLinePos() : tokPos;
+ tokCommentsBefore = tokComments;
+ if (forceRegexp) return readRegexp();
+ if (tokPos >= inputLen) return finishToken(_eof);
+
+ var code = input.charCodeAt(tokPos); |
| Identifier or keyword. '\uXXXX' sequences are allowed in +identifiers, so '\' also dispatches to that. | if (isIdentifierStart(code) || code === 92 /* '\' */) return readWord();
+ var next = input.charCodeAt(tokPos+1);
+
+ switch(code) { |
| The interpretation of a dot depends on whether it is followed +by a digit. | case 46: // '.'
+ if (next >= 48 && next <= 57) return readNumber(String.fromCharCode(code));
+ ++tokPos;
+ return finishToken(_dot); |
| Punctuation tokens. | case 40: ++tokPos; return finishToken(_parenL);
+ case 41: ++tokPos; return finishToken(_parenR);
+ case 59: ++tokPos; return finishToken(_semi);
+ case 44: ++tokPos; return finishToken(_comma);
+ case 91: ++tokPos; return finishToken(_bracketL);
+ case 93: ++tokPos; return finishToken(_bracketR);
+ case 123: ++tokPos; return finishToken(_braceL);
+ case 125: ++tokPos; return finishToken(_braceR);
+ case 58: ++tokPos; return finishToken(_colon);
+ case 63: ++tokPos; return finishToken(_question); |
| '0x' is a hexadecimal number. | case 48: // '0'
+ if (next === 120 || next === 88) return readHexNumber(); |
| Anything else beginning with a digit is an integer, octal +number, or float. | case 49: case 50: case 51: case 52: case 53: case 54: case 55: case 56: case 57: // 1-9
+ return readNumber(String.fromCharCode(code)); |
| Quotes produce strings. | case 34: case 39: // '"', "'"
+ return readString(String.fromCharCode(code)); |
| Operators are parsed inline in tiny state machines. '=' (61) is
+often referred to. | case 47: // '/'
+ if (tokRegexpAllowed) {++tokPos; return readRegexp();}
+ if (next === 61) return finishOp(_assign, 2);
+ return finishOp(_slash, 1);
+
+ case 37: case 42: // '%*'
+ if (next === 61) return finishOp(_assign, 2);
+ return finishOp(_bin10, 1);
+
+ case 124: case 38: // '|&'
+ if (next === code) return finishOp(code === 124 ? _bin1 : _bin2, 2);
+ if (next === 61) return finishOp(_assign, 2);
+ return finishOp(code === 124 ? _bin3 : _bin5, 1);
+
+ case 94: // '^'
+ if (next === 61) return finishOp(_assign, 2);
+ return finishOp(_bin4, 1);
+
+ case 43: case 45: // '+-'
+ if (next === code) return finishOp(_incdec, 2);
+ if (next === 61) return finishOp(_assign, 2);
+ return finishOp(_plusmin, 1);
+
+ case 60: case 62: // '<>'
+ var size = 1;
+ if (next === code) {
+ size = code === 62 && input.charCodeAt(tokPos+2) === 62 ? 3 : 2;
+ if (input.charCodeAt(tokPos + size) === 61) return finishOp(_assign, size + 1);
+ return finishOp(_bin8, size);
+ }
+ if (next === 61)
+ size = input.charCodeAt(tokPos+2) === 61 ? 3 : 2;
+ return finishOp(_bin7, size);
+
+ case 61: case 33: // '=!'
+ if (next === 61) return finishOp(_bin6, input.charCodeAt(tokPos+2) === 61 ? 3 : 2);
+ return finishOp(code === 61 ? _eq : _prefix, 1);
+
+ case 126: // '~'
+ if (next === 61) return finishOp(_assign, 2);
+ return finishOp(_prefix, 1);
+ } |
| If we are here, we either found a non-ASCII identifier +character, or something that's entirely disallowed. | var ch = String.fromCharCode(code);
+ if (ch === "\\" || nonASCIIidentifierStart.test(ch)) return readWord();
+ raise(tokPos, "Unexpected character '" + ch + "'");
+ }
+
+ function finishOp(type, size) {
+ var str = input.slice(tokPos, tokPos + size);
+ tokPos += size;
+ finishToken(type, str);
+ } |
| Parse a regular expression. Some context-awareness is necessary, +since a '/' inside a '[]' set does not end the expression. | function readRegexp() {
+ var content = "", escaped, inClass, start = tokPos;
+ for (;;) {
+ if (tokPos >= inputLen) raise(start, "Unterminated regular expression");
+ var ch = input.charAt(tokPos);
+ if (newline.test(ch)) raise(start, "Unterminated regular expression");
+ if (!escaped) {
+ if (ch === "[") inClass = true;
+ else if (ch === "]" && inClass) inClass = false;
+ else if (ch === "/" && !inClass) break;
+ escaped = ch === "\\";
+ } else escaped = false;
+ ++tokPos;
+ }
+ var content = input.slice(start, tokPos);
+ ++tokPos; |
| Need to use | var mods = readWord1();
+ if (mods && !/^[gmsiy]*$/.test(mods)) raise(start, "Invalid regexp flag");
+ return finishToken(_regexp, new RegExp(content, mods));
+ } |
| Read an integer in the given radix. Return null if zero digits
+were read, the integer value otherwise. When | function readInt(radix, len) {
+ var start = tokPos, total = 0;
+ for (;;) {
+ var code = input.charCodeAt(tokPos), val;
+ if (code >= 97) val = code - 97 + 10; // a
+ else if (code >= 65) val = code - 65 + 10; // A
+ else if (code >= 48 && code <= 57) val = code - 48; // 0-9
+ else val = Infinity;
+ if (val >= radix) break;
+ ++tokPos;
+ total = total * radix + val;
+ }
+ if (tokPos === start || len != null && tokPos - start !== len) return null;
+
+ return total;
+ }
+
+ function readHexNumber() {
+ tokPos += 2; // 0x
+ var val = readInt(16);
+ if (val == null) raise(tokStart + 2, "Expected hexadecimal number");
+ if (isIdentifierStart(input.charCodeAt(tokPos))) raise(tokPos, "Identifier directly after number");
+ return finishToken(_num, val);
+ } |
| Read an integer, octal integer, or floating-point number. |
+ function readNumber(ch) {
+ var start = tokPos, isFloat = ch === ".";
+ if (!isFloat && readInt(10) == null) raise(start, "Invalid number");
+ if (isFloat || input.charAt(tokPos) === ".") {
+ var next = input.charAt(++tokPos);
+ if (next === "-" || next === "+") ++tokPos;
+ if (readInt(10) === null) raise(start, "Invalid number");
+ isFloat = true;
+ }
+ if (/e/i.test(input.charAt(tokPos))) {
+ var next = input.charAt(++tokPos);
+ if (next === "-" || next === "+") ++tokPos;
+ if (readInt(10) === null) raise(start, "Invalid number")
+ isFloat = true;
+ }
+ if (isIdentifierStart(input.charCodeAt(tokPos))) raise(tokPos, "Identifier directly after number");
+
+ var str = input.slice(start, tokPos), val;
+ if (isFloat) val = parseFloat(str);
+ else if (ch !== "0" || str.length === 1) val = parseInt(str, 10);
+ else if (/[89]/.test(str) || strict) raise(start, "Invalid number");
+ else val = parseInt(str, 8);
+ return finishToken(_num, val);
+ } |
| Read a string value, interpreting backslash-escapes. | function readString(quote) {
+ tokPos++;
+ var str = "";
+ for (;;) {
+ if (tokPos >= inputLen) raise(tokStart, "Unterminated string constant");
+ var ch = input.charAt(tokPos);
+ if (ch === quote) {
+ ++tokPos;
+ return finishToken(_string, str);
+ }
+ if (ch === "\\") {
+ ch = input.charAt(++tokPos);
+ var octal = /^[0-7]+/.exec(input.slice(tokPos, tokPos + 3));
+ if (octal) octal = octal[0];
+ while (octal && parseInt(octal, 8) > 255) octal = octal.slice(0, octal.length - 1);
+ ++tokPos;
+ if (octal) {
+ if (strict) raise(tokPos - 2, "Octal literal in strict mode");
+ str += String.fromCharCode(parseInt(octal, 8));
+ tokPos += octal.length - 1;
+ } else if (ch === "x") {
+ str += readHexChar(2);
+ } else if (ch === "u") {
+ str += readHexChar(4);
+ } else if (ch === "U") {
+ str += readHexChar(8);
+ } else {
+ switch (ch) {
+ case "n" : str += "\n"; break;
+ case "r" : str += "\r"; break;
+ case "t" : str += "\t"; break;
+ case "b" : str += "\b"; break;
+ case "v" : str += "\u000b"; break;
+ case "f" : str += "\f"; break;
+ case "0" : str += "\0"; break;
+ case "\r": if (input.charAt(tokPos) === "\n") ++tokPos;
+ case "\n": break;
+ default: str += ch; break;
+ }
+ }
+ } else {
+ if (newline.test(ch)) raise(tokStart, "Unterminated string constant");
+ if (ch !== "\\") str += ch;
+ ++tokPos;
+ }
+ }
+ } |
| Used to read character escape sequences ('\x', '\u', '\U'). | function readHexChar(len) {
+ var n = readInt(16, len);
+ if (n === null) raise(tokStart, "Bad character escape sequence");
+ return String.fromCharCode(n);
+ } |
| Used to signal to callers of | var containsEsc; |
| Read an identifier, and return it as a string. Sets Only builds up the word character-by-character when it actually +containeds an escape, as a micro-optimization. | function readWord1() {
+ containsEsc = false;
+ var word, first = true, start = tokPos;
+ for (;;) {
+ var ch = input.charAt(tokPos);
+ if (isIdentifierChar(ch)) {
+ if (containsEsc) word += ch;
+ ++tokPos;
+ } else if (ch === "\\") {
+ if (!containsEsc) word = input.slice(start, tokPos);
+ containsEsc = true;
+ if (input.charAt(++tokPos) != "u")
+ raise(tokPos, "Expecting Unicode escape sequence \\uXXXX");
+ ++tokPos;
+ var esc = readHexChar(4);
+ if (!esc) raise(tokPos - 1, "Invalid Unicode escape");
+ if (!(first ? isIdentifierStart(esc.charCodeAt(0)) : isIdentifierChar(esc)))
+ raise(tokPos - 4, "Invalid Unicode escape");
+ word += esc;
+ } else {
+ break;
+ }
+ first = false;
+ }
+ return containsEsc ? word : input.slice(start, tokPos);
+ } |
| Read an identifier or keyword token. Will check for reserved +words when necessary. | function readWord() {
+ var word = readWord1();
+ var type = _name;
+ if (!containsEsc) {
+ if (isKeyword(word)) type = keywordTypes[word];
+ else if (options.forbidReserved &&
+ (options.ecmaVersion === 3 ? isReservedWord3 : isReservedWord5)(word) ||
+ strict && isStrictReservedWord(word))
+ raise(tokStart, "The keyword '" + word + "' is reserved");
+ }
+ return finishToken(type, word);
+ } |
Parser | |
| A recursive descent parser operates by defining functions for all
+syntactic elements, and recursively calling those, each function
+advancing the input stream and returning an AST node. Precedence
+of constructs (for example, the fact that Acorn uses an operator precedence parser to handle binary +operator precedence, because it is much more compact than using +the technique outlined above, which uses different, nesting +functions to specify precedence, for all of the ten binary +precedence levels that JavaScript defines. | |
Parser utilities | |
| Continue to the next token. |
+ function next() {
+ lastStart = tokStart;
+ lastEnd = tokEnd;
+ readToken();
+ } |
| Enter strict mode. Re-reads the next token to please pedantic +tests ("use strict"; 010; -- should fail). | function setStrict(strct) {
+ strict = strct;
+ tokPos = options.linePositions ? lastEnd.offset : lastEnd;
+ skipSpace();
+ readToken();
+ } |
| Start an AST node, attaching a start offset and optionally a
+ | function startNode() {
+ var node = {type: null, start: tokStart, end: null};
+ if (options.trackComments && tokCommentsBefore) {
+ node.commentsBefore = tokCommentsBefore;
+ tokCommentsBefore = null;
+ }
+ return node;
+ } |
| Start a node whose start offset/comments information should be +based on the start of another node. For example, a binary +operator node is only started after its left-hand side has +already been parsed. | function startNodeFrom(other) {
+ var node = {type: null, start: other.start};
+ if (other.commentsBefore) {
+ node.commentsBefore = other.commentsBefore;
+ other.commentsBefore = null;
+ }
+ return node;
+ } |
| Finish an AST node, adding We keep track of the last node that we finished, in order
+'bubble' | var lastFinishedNode;
+
+ function finishNode(node, type) {
+ node.type = type;
+ node.end = lastEnd;
+ if (options.trackComments) {
+ if (tokCommentsAfter) {
+ node.commentsAfter = tokCommentsAfter;
+ tokCommentsAfter = null;
+ } else if (lastFinishedNode && lastFinishedNode.end === lastEnd) {
+ node.commentsAfter = lastFinishedNode.commentsAfter;
+ lastFinishedNode.commentsAfter = null;
+ }
+ lastFinishedNode = node;
+ }
+ return node;
+ } |
| Test whether a statement node is the string literal | function isUseStrict(stmt) {
+ return options.ecmaVersion >= 5 && stmt.type === "ExpressionStatement" &&
+ stmt.expression.type === "Literal" && stmt.expression.value === "use strict";
+ } |
| Predicate that tests whether the next token is of the given +type, and if yes, consumes it as a side effect. | function eat(type) {
+ if (tokType === type) {
+ next();
+ return true;
+ }
+ } |
| Test whether a semicolon can be inserted at the current position. | function canInsertSemicolon() {
+ return tokType === _eof || tokType === _braceR ||
+ !options.strictSemicolons &&
+ newline.test(options.linePositions ? input.slice(lastEnd.offset, tokStart.offset)
+ : input.slice(lastEnd, tokStart));
+ } |
| Consume a semicolon, or, failing that, see if we are allowed to +pretend that there is a semicolon at this position. | function semicolon() {
+ if (!eat(_semi) && !canInsertSemicolon()) unexpected();
+ } |
| Expect a token of a given type. If found, consume it, otherwise, +raise an unexpected token error. | function expect(type) {
+ if (tokType === type) next();
+ else unexpected();
+ } |
| Raise an unexpected token error. | function unexpected() {
+ raise(tokStart, "Unexpected token");
+ } |
| Verify that a node is an lval — something that can be assigned +to. | function checkLVal(expr) {
+ if (expr.type !== "Identifier" && expr.type !== "MemberExpression")
+ raise(expr.start, "Assigning to rvalue");
+ if (strict && expr.type === "Identifier" && isStrictBadIdWord(expr.name))
+ raise(expr.start, "Assigning to " + expr.name + " in strict mode");
+ } |
Statement parsing | |
| Parse a program. Initializes the parser, reads any number of +statements, and wraps them in a Program node. | function parseTopLevel() {
+ initTokenState();
+ lastStart = lastEnd = options.linePositions ? curLinePos() : tokPos;
+ inFunction = strict = null;
+ labels = [];
+ readToken();
+
+ var node = startNode(), first = true;
+ node.body = [];
+ while (tokType !== _eof) {
+ var stmt = parseStatement();
+ node.body.push(stmt);
+ if (first && isUseStrict(stmt)) setStrict(true);
+ first = false;
+ }
+ return finishNode(node, "Program");
+ };
+
+ var loopLabel = {kind: "loop"}, switchLabel = {kind: "switch"}; |
| Parse a single statement. + +If expecting a statement and finding a slash operator, parse a
+regular expression literal. This is to handle cases like
+ | function parseStatement() {
+ if (tokType === _slash)
+ readToken(true);
+
+ var starttype = tokType, node = startNode(); |
| Most types of statements are recognized by the keyword they +start with. Many are trivial to parse, some require a bit of +complexity. | switch (starttype) {
+ case _break: case _continue:
+ next();
+ var isBreak = starttype === _break;
+ if (eat(_semi) || canInsertSemicolon()) node.label = null;
+ else if (tokType !== _name) unexpected();
+ else {
+ node.label = parseIdent();
+ semicolon();
+ } |
| Verify that there is an actual destination to break or +continue to. | for (var i = 0; i < labels.length; ++i) {
+ var lab = labels[i];
+ if ((node.label == null || lab.name === node.label.name) &&
+ lab.kind != null && (isBreak || lab.kind === "loop")) break;
+ }
+ if (i === labels.length) raise(node.start, "Unsyntactic " + starttype.keyword);
+ return finishNode(node, isBreak ? "BreakStatement" : "ContinueStatement");
+
+ case _debugger:
+ next();
+ return finishNode(node, "DebuggerStatement");
+
+ case _do:
+ next();
+ labels.push(loopLabel);
+ node.body = parseStatement();
+ labels.pop();
+ expect(_while);
+ node.test = parseParenExpression();
+ return finishNode(node, "DoWhileStatement"); |
| Disambiguating between a | case _for:
+ next();
+ labels.push(loopLabel);
+ expect(_parenL);
+ if (tokType === _semi) return parseFor(node, null);
+ if (tokType === _var) {
+ var init = startNode();
+ next();
+ parseVar(init, true);
+ if (init.declarations.length === 1 && eat(_in))
+ return parseForIn(node, init);
+ return parseFor(node, init);
+ }
+ var init = parseExpression(false, true);
+ if (eat(_in)) {checkLVal(init); return parseForIn(node, init);}
+ return parseFor(node, init);
+
+ case _function:
+ next();
+ return parseFunction(node, true);
+
+ case _if:
+ next();
+ node.test = parseParenExpression();
+ node.consequent = parseStatement();
+ node.alternate = eat(_else) ? parseStatement() : null;
+ return finishNode(node, "IfStatement");
+
+ case _return:
+ if (!inFunction) raise(tokStart, "'return' outside of function");
+ next(); |
| In |
+ if (eat(_semi) || canInsertSemicolon()) node.argument = null;
+ else { node.argument = parseExpression(); semicolon(); }
+ return finishNode(node, "ReturnStatement");
+
+ case _switch:
+ next();
+ node.discriminant = parseParenExpression();
+ node.cases = [];
+ expect(_braceL);
+ labels.push(switchLabel); |
| Statements under must be grouped (by label) in SwitchCase
+nodes. |
+ for (var cur, sawDefault; tokType != _braceR;) {
+ if (tokType === _case || tokType === _default) {
+ var isCase = tokType === _case;
+ if (cur) finishNode(cur, "SwitchCase");
+ node.cases.push(cur = startNode());
+ cur.consequent = [];
+ next();
+ if (isCase) cur.test = parseExpression();
+ else {
+ if (sawDefault) raise(lastStart, "Multiple default clauses"); sawDefault = true;
+ cur.test = null;
+ }
+ expect(_colon);
+ } else {
+ if (!cur) unexpected();
+ cur.consequent.push(parseStatement());
+ }
+ }
+ if (cur) finishNode(cur, "SwitchCase");
+ next(); // Closing brace
+ labels.pop();
+ return finishNode(node, "SwitchStatement");
+
+ case _throw:
+ next();
+ node.argument = parseExpression();
+ return finishNode(node, "ThrowStatement");
+
+ case _try:
+ next();
+ node.block = parseBlock();
+ node.handlers = [];
+ while (tokType === _catch) {
+ var clause = startNode();
+ next();
+ expect(_parenL);
+ clause.param = parseIdent();
+ if (strict && isStrictBadIdWord(clause.param.name))
+ raise(clause.param.start, "Binding " + clause.param.name + " in strict mode");
+ expect(_parenR);
+ clause.guard = null;
+ clause.body = parseBlock();
+ node.handlers.push(finishNode(clause, "CatchClause"));
+ }
+ node.finalizer = eat(_finally) ? parseBlock() : null;
+ if (!node.handlers.length && !node.finalizer)
+ raise(node.start, "Missing catch or finally clause");
+ return finishNode(node, "TryStatement");
+
+ case _var:
+ next();
+ node = parseVar(node);
+ semicolon();
+ return node;
+
+ case _while:
+ next();
+ node.test = parseParenExpression();
+ labels.push(loopLabel);
+ node.body = parseStatement();
+ labels.pop();
+ return finishNode(node, "WhileStatement");
+
+ case _with:
+ if (strict) raise(tokStart, "'with' in strict mode");
+ next();
+ node.object = parseParenExpression();
+ node.body = parseStatement();
+ return finishNode(node, "WithStatement");
+
+ case _braceL:
+ return parseBlock();
+
+ case _semi:
+ next();
+ return finishNode(node, "EmptyStatement"); |
| If the statement does not start with a statement keyword or a +brace, it's an ExpressionStatement or LabeledStatement. We +simply start parsing an expression, and afterwards, if the +next token is a colon and the expression was a simple +Identifier node, we switch to interpreting it as a label. | default:
+ var maybeName = tokVal, expr = parseExpression();
+ if (starttype === _name && expr.type === "Identifier" && eat(_colon)) {
+ for (var i = 0; i < labels.length; ++i)
+ if (labels[i].name === maybeName) raise(expr.start, "Label '" + maybeName + "' is already declared");
+ var kind = tokType.isLoop ? "loop" : tokType === _switch ? "switch" : null;
+ labels.push({name: maybeName, kind: kind});
+ node.body = parseStatement();
+ node.label = expr;
+ return finishNode(node, "LabeledStatement");
+ } else {
+ node.expression = expr;
+ semicolon();
+ return finishNode(node, "ExpressionStatement");
+ }
+ }
+ } |
| Used for constructs like | function parseParenExpression() {
+ expect(_parenL);
+ var val = parseExpression();
+ expect(_parenR);
+ return val;
+ } |
| Parse a semicolon-enclosed block of statements, handling | function parseBlock(allowStrict) {
+ var node = startNode(), first = true, strict = false, oldStrict;
+ node.body = [];
+ expect(_braceL);
+ while (!eat(_braceR)) {
+ var stmt = parseStatement();
+ node.body.push(stmt);
+ if (first && isUseStrict(stmt)) {
+ oldStrict = strict;
+ setStrict(strict = true);
+ }
+ first = false
+ }
+ if (strict && !oldStrict) setStrict(false);
+ return finishNode(node, "BlockStatement");
+ } |
| Parse a regular | function parseFor(node, init) {
+ node.init = init;
+ expect(_semi);
+ node.test = tokType === _semi ? null : parseExpression();
+ expect(_semi);
+ node.update = tokType === _parenR ? null : parseExpression();
+ expect(_parenR);
+ node.body = parseStatement();
+ labels.pop();
+ return finishNode(node, "ForStatement");
+ } |
| Parse a | function parseForIn(node, init) {
+ node.left = init;
+ node.right = parseExpression();
+ expect(_parenR);
+ node.body = parseStatement();
+ labels.pop();
+ return finishNode(node, "ForInStatement");
+ } |
| Parse a list of variable declarations. | function parseVar(node, noIn) {
+ node.declarations = [];
+ node.kind = "var";
+ for (;;) {
+ var decl = startNode();
+ decl.id = parseIdent();
+ if (strict && isStrictBadIdWord(decl.id.name))
+ raise(decl.id.start, "Binding " + decl.id.name + " in strict mode");
+ decl.init = eat(_eq) ? parseExpression(true, noIn) : null;
+ node.declarations.push(finishNode(decl, "VariableDeclarator"));
+ if (!eat(_comma)) break;
+ }
+ return finishNode(node, "VariableDeclaration");
+ } |
Expression parsing | |
| These nest, from the most general expression type at the top to +'atomic', nondivisible expression types at the bottom. Most of +the functions will simply let the function(s) below them parse, +and, if the syntactic construct they handle is present, wrap +the AST node that the inner parser gave them in another node. | |
| Parse a full expression. The arguments are used to forbid comma
+sequences (in argument lists, array literals, or object literals)
+or the | function parseExpression(noComma, noIn) {
+ var expr = parseMaybeAssign(noIn);
+ if (!noComma && tokType === _comma) {
+ var node = startNodeFrom(expr);
+ node.expressions = [expr];
+ while (eat(_comma)) node.expressions.push(parseMaybeAssign(noIn));
+ return finishNode(node, "SequenceExpression");
+ }
+ return expr;
+ } |
| Parse an assignment expression. This includes applications of
+operators like | function parseMaybeAssign(noIn) {
+ var left = parseMaybeConditional(noIn);
+ if (tokType.isAssign) {
+ var node = startNodeFrom(left);
+ node.operator = tokVal;
+ node.left = left;
+ next();
+ node.right = parseMaybeAssign(noIn);
+ checkLVal(left);
+ return finishNode(node, "AssignmentExpression");
+ }
+ return left;
+ } |
| Parse a ternary conditional ( | function parseMaybeConditional(noIn) {
+ var expr = parseExprOps(noIn);
+ if (eat(_question)) {
+ var node = startNodeFrom(expr);
+ node.test = expr;
+ node.consequent = parseExpression(true);
+ expect(_colon);
+ node.alternate = parseExpression(true, noIn);
+ return finishNode(node, "ConditionalExpression");
+ }
+ return expr;
+ } |
| Start the precedence parser. | function parseExprOps(noIn) {
+ return parseExprOp(parseMaybeUnary(noIn), -1, noIn);
+ } |
| Parse binary operators with the operator precedence parsing
+algorithm. | function parseExprOp(left, minPrec, noIn) {
+ var prec = tokType.binop;
+ if (prec != null && (!noIn || tokType !== _in)) {
+ if (prec > minPrec) {
+ var node = startNodeFrom(left);
+ node.left = left;
+ node.operator = tokVal;
+ next();
+ node.right = parseExprOp(parseMaybeUnary(noIn), prec, noIn);
+ var node = finishNode(node, /&&|\|\|/.test(node.operator) ? "LogicalExpression" : "BinaryExpression");
+ return parseExprOp(node, minPrec, noIn);
+ }
+ }
+ return left;
+ } |
| Parse unary operators, both prefix and postfix. | function parseMaybeUnary(noIn) {
+ if (tokType.prefix) {
+ var node = startNode(), update = tokType.isUpdate;
+ node.operator = tokVal;
+ node.prefix = true;
+ next();
+ node.argument = parseMaybeUnary(noIn);
+ if (update) checkLVal(node.argument);
+ else if (strict && node.operator === "delete" &&
+ node.argument.type === "Identifier")
+ raise(node.start, "Deleting local variable in strict mode");
+ return finishNode(node, update ? "UpdateExpression" : "UnaryExpression");
+ }
+ var expr = parseExprSubscripts();
+ while (tokType.postfix && !canInsertSemicolon()) {
+ var node = startNodeFrom(expr);
+ node.operator = tokVal;
+ node.prefix = false;
+ node.argument = expr;
+ checkLVal(expr);
+ next();
+ expr = finishNode(node, "UpdateExpression");
+ }
+ return expr;
+ } |
| Parse call, dot, and | function parseExprSubscripts() {
+ return parseSubscripts(parseExprAtom());
+ }
+
+ function parseSubscripts(base, noCalls) {
+ if (eat(_dot)) {
+ var node = startNodeFrom(base);
+ node.object = base;
+ node.property = parseIdent(true);
+ node.computed = false;
+ return parseSubscripts(finishNode(node, "MemberExpression"), noCalls);
+ } else if (eat(_bracketL)) {
+ var node = startNodeFrom(base);
+ node.object = base;
+ node.property = parseExpression();
+ node.computed = true;
+ expect(_bracketR);
+ return parseSubscripts(finishNode(node, "MemberExpression"), noCalls);
+ } else if (!noCalls && eat(_parenL)) {
+ var node = startNodeFrom(base);
+ node.callee = base;
+ node.arguments = parseExprList(_parenR, false);
+ return parseSubscripts(finishNode(node, "CallExpression"), noCalls);
+ } else return base;
+ } |
| Parse an atomic expression — either a single token that is an
+expression, an expression started by a keyword like | function parseExprAtom() {
+ switch (tokType) {
+ case _name:
+ if (tokVal === "this") {
+ var node = startNode();
+ next();
+ return finishNode(node, "ThisExpression");
+ } else return parseIdent();
+
+ case _num: case _string: case _regexp:
+ var node = startNode();
+ node.value = tokVal;
+ next();
+ return finishNode(node, "Literal");
+
+ case _null: case _true: case _false:
+ var node = startNode();
+ node.value = tokType.atomValue;
+ next();
+ return finishNode(node, "Literal");
+
+ case _parenL:
+ next();
+ var val = parseExpression();
+ expect(_parenR);
+ return val;
+
+ case _bracketL:
+ var node = startNode();
+ next();
+ node.elements = parseExprList(_bracketR, true, true);
+ return finishNode(node, "ArrayExpression");
+
+ case _braceL:
+ return parseObj();
+
+ case _function:
+ var node = startNode();
+ next();
+ return parseFunction(node, false);
+
+ case _new:
+ return parseNew();
+
+ default:
+ unexpected();
+ }
+ } |
| New's precedence is slightly tricky. It must allow its argument
+to be a | function parseNew() {
+ var node = startNode();
+ next();
+ node.callee = parseSubscripts(parseExprAtom(false), true);
+ if (eat(_parenL)) node.arguments = parseExprList(_parenR, false);
+ else node.arguments = [];
+ return finishNode(node, "NewExpression");
+ } |
| Parse an object literal. | function parseObj() {
+ var node = startNode(), first = true, sawGetSet = false;
+ node.properties = [];
+ next();
+ while (!eat(_braceR)) {
+ if (!first) {
+ expect(_comma);
+ if (options.allowTrailingCommas && eat(_braceR)) break;
+ } else first = false;
+
+ var prop = {key: parsePropertyName()}, isGetSet = false, kind;
+ if (eat(_colon)) {
+ prop.value = parseExpression(true);
+ kind = prop.kind = "init";
+ } else if (options.ecmaVersion >= 5 && prop.key.type === "Identifier" &&
+ (prop.key.name === "get" || prop.key.name === "set")) {
+ isGetSet = sawGetSet = true;
+ kind = prop.kind = prop.key.name;
+ prop.key = parsePropertyName();
+ if (!tokType === _parenL) unexpected();
+ prop.value = parseFunction(startNode(), false);
+ } else unexpected(); |
| getters and setters are not allowed to clash — either with +each other or with an init property — and in strict mode, +init properties are also not allowed to be repeated. | if (prop.key.type === "Identifier" && (strict || sawGetSet)) {
+ for (var i = 0; i < node.properties.length; ++i) {
+ var other = node.properties[i];
+ if (other.key.name === prop.key.name) {
+ var conflict = kind == other.kind || isGetSet && other.kind === "init" ||
+ kind === "init" && (other.kind === "get" || other.kind === "set");
+ if (conflict && !strict && kind === "init" && other.kind === "init") conflict = false;
+ if (conflict) raise(prop.key.start, "Redefinition of property");
+ }
+ }
+ }
+ node.properties.push(prop);
+ }
+ return finishNode(node, "ObjectExpression");
+ }
+
+ function parsePropertyName() {
+ if (tokType === _num || tokType === _string) return parseExprAtom();
+ return parseIdent(true);
+ } |
| Parse a function declaration or literal (depending on the
+ | function parseFunction(node, isStatement) {
+ if (tokType === _name) node.id = parseIdent();
+ else if (isStatement) unexpected();
+ else node.id = null;
+ node.params = [];
+ var first = true;
+ expect(_parenL);
+ while (!eat(_parenR)) {
+ if (!first) expect(_comma); else first = false;
+ node.params.push(parseIdent());
+ } |
| Start a new scope with regard to labels and the | var oldInFunc = inFunction, oldLabels = labels;
+ inFunction = true; labels = [];
+ node.body = parseBlock(true);
+ inFunction = oldInFunc; labels = oldLabels; |
| If this is a strict mode function, verify that argument names
+are not repeated, and it does not try to bind the words | if (strict || node.body.body.length && isUseStrict(node.body.body[0])) {
+ for (var i = node.id ? -1 : 0; i < node.params.length; ++i) {
+ var id = i < 0 ? node.id : node.params[i];
+ if (isStrictReservedWord(id.name) || isStrictBadIdWord(id.name))
+ raise(id.start, "Defining '" + id.name + "' in strict mode");
+ if (i >= 0) for (var j = 0; j < i; ++j) if (id.name === node.params[j].name)
+ raise(id.start, "Argument name clash in strict mode");
+ }
+ }
+
+ return finishNode(node, isStatement ? "FunctionDeclaration" : "FunctionExpression");
+ } |
| Parses a comma-separated list of expressions, and returns them as
+an array. | function parseExprList(close, allowTrailingComma, allowEmpty) {
+ var elts = [], first = true;
+ while (!eat(close)) {
+ if (!first) {
+ expect(_comma);
+ if (allowTrailingComma && options.allowTrailingCommas && eat(close)) break;
+ } else first = false;
+
+ if (allowEmpty && tokType === _comma) elts.push(null);
+ else elts.push(parseExpression(true));
+ }
+ return elts;
+ } |
| Parse the next token as an identifier. If | function parseIdent(liberal) {
+ var node = startNode();
+ node.name = tokType === _name ? tokVal : (liberal && tokType.keyword) || unexpected();
+ next();
+ return finishNode(node, "Identifier");
+ }
+
+})(typeof exports === "undefined" ? (window.acorn = {}) : exports);
+
+ |