1 // Copyright 2003 Adam Megacz, see the COPYING file for licensing [GPL]
8 * Parses a stream of lexed tokens into a tree of JSFunction's.
10 * There are three kinds of things we parse: blocks, statements, and
13 * - Expressions are a special type of statement that evaluates to a
14 * value (for example, "break" is not an expression, * but "3+2"
15 * is). Some tokens sequences start expressions (for * example,
16 * literal numbers) and others continue an expression which * has
17 * already been begun (for example, '+'). Finally, some *
18 * expressions are valid targets for an assignment operation; after
19 * * each of these expressions, continueExprAfterAssignable() is
20 * called * to check for an assignment operation.
22 * - A statement ends with a semicolon and does not return a value.
24 * - A block is a single statement or a sequence of statements
25 * surrounded by curly braces.
27 * Each parsing method saves the parserLine before doing its actual
28 * work and restores it afterwards. This ensures that parsing a
29 * subexpression does not modify the line number until a token
30 * *after* the subexpression has been consumed by the parent
33 * Technically it would be a better design for this class to build an
34 * intermediate parse tree and use that to emit bytecode. Here's the
37 * Advantages of building a parse tree:
38 * - easier to apply optimizations
39 * - would let us handle more sophisticated languages than JavaScript
41 * Advantages of leaving out the parse tree
42 * - faster compilation
43 * - less load on the garbage collector
44 * - much simpler code, easier to understand
47 * Fortunately JS is such a simple language that we can get away with
48 * the half-assed approach and still produce a working, complete
51 * The bytecode language emitted doesn't really cause any appreciable
52 * semantic loss, and is itself a parseable language very similar to
53 * Forth or a postfix variant of LISP. This means that the bytecode
54 * can be transformed into a parse tree, which can be manipulated.
55 * So if we ever want to add an optimizer, it could easily be done by
56 * producing a parse tree from the bytecode, optimizing that tree,
57 * and then re-emitting the bytecode. The parse tree node class
58 * would also be much simpler since the bytecode language has so few
61 * Actually, the above paragraph is slightly inaccurate -- there are
62 * places where we push a value and then perform an arbitrary number
63 * of operations using it before popping it; this doesn't parse well.
64 * But these cases are clearly marked and easy to change if we do
65 * need to move to a parse tree format.
67 class Parser extends Lexer implements ByteCodes {
70 // Constructors //////////////////////////////////////////////////////
72 public Parser(Reader r, String sourceName, int line) throws IOException { super(r, sourceName, line); }
75 public static void main(String[] s) throws Exception {
76 JSFunction block = JSFunction.fromReader("stdin", 0, new InputStreamReader(System.in));
77 if (block == null) return;
78 System.out.println(block);
82 // Statics ////////////////////////////////////////////////////////////
84 static byte[] precedence = new byte[MAX_TOKEN + 1];
85 static boolean[] isRightAssociative = new boolean[MAX_TOKEN + 1];
86 // Use this as the precedence when we want anything up to the comma
87 private final static int NO_COMMA = 2;
89 isRightAssociative[ASSIGN] =
90 isRightAssociative[ASSIGN_BITOR] =
91 isRightAssociative[ASSIGN_BITXOR] =
92 isRightAssociative[ASSIGN_BITAND] =
93 isRightAssociative[ASSIGN_LSH] =
94 isRightAssociative[ASSIGN_RSH] =
95 isRightAssociative[ASSIGN_URSH] =
96 isRightAssociative[ASSIGN_ADD] =
97 isRightAssociative[ASSIGN_SUB] =
98 isRightAssociative[ASSIGN_MUL] =
99 isRightAssociative[ASSIGN_DIV] =
100 isRightAssociative[ASSIGN_MOD] = true;
102 precedence[COMMA] = 1;
103 // 2 is intentionally left unassigned. we use minPrecedence==2 for comma separated lists
105 precedence[ASSIGN_BITOR] =
106 precedence[ASSIGN_BITXOR] =
107 precedence[ASSIGN_BITAND] =
108 precedence[ASSIGN_LSH] =
109 precedence[ASSIGN_RSH] =
110 precedence[ASSIGN_URSH] =
111 precedence[ASSIGN_ADD] =
112 precedence[ASSIGN_SUB] =
113 precedence[ASSIGN_MUL] =
114 precedence[ASSIGN_DIV] =
115 precedence[ASSIGN_MOD] = 3;
116 precedence[HOOK] = 4;
119 precedence[BITOR] = 7;
120 precedence[BITXOR] = 8;
121 precedence[BITAND] = 9;
122 precedence[EQ] = precedence[NE] = precedence[SHEQ] = precedence[SHNE] = 10;
123 precedence[LT] = precedence[LE] = precedence[GT] = precedence[GE] = 11;
124 precedence[LSH] = precedence[RSH] = precedence[URSH] = 12;
125 precedence[ADD] = precedence[SUB] = 12;
126 precedence[MUL] = precedence[DIV] = precedence[MOD] = 13;
127 precedence[BITNOT] = precedence[BANG] = precedence[TYPEOF] = 14;
128 precedence[DOT] = precedence[LB] = precedence[LP] = precedence[INC] = precedence[DEC] = 15;
132 // Parsing Logic /////////////////////////////////////////////////////////
134 /** gets a token and throws an exception if it is not <tt>code</tt> */
135 private void consume(int code) throws IOException {
136 if (getToken() != code) throw pe("expected " + codeToString[code] + ", got " + (op == -1 ? "EOF" : codeToString[op]));
140 * Parse the largest possible expression containing no operators
141 * of precedence below <tt>minPrecedence</tt> and append the
142 * bytecodes for that expression to <tt>appendTo</tt>; the
143 * appended bytecodes MUST grow the stack by exactly one element.
145 private void startExpr(JSFunction appendTo, int minPrecedence) throws IOException {
146 int saveParserLine = parserLine;
147 _startExpr(appendTo, minPrecedence);
148 parserLine = saveParserLine;
150 private void _startExpr(JSFunction appendTo, int minPrecedence) throws IOException {
151 int tok = getToken();
152 JSFunction b = appendTo;
155 case -1: throw pe("expected expression");
157 // all of these simply push values onto the stack
158 case NUMBER: b.add(parserLine, LITERAL, number); break;
159 case STRING: b.add(parserLine, LITERAL, string); break;
160 case NULL: b.add(parserLine, LITERAL, null); break;
161 case TRUE: case FALSE: b.add(parserLine, LITERAL, JS.B(tok == TRUE)); break;
164 b.add(parserLine, ARRAY, JS.ZERO); // push an array onto the stack
167 if (peekToken() != RB)
168 while(true) { // iterate over the initialization values
170 b.add(parserLine, LITERAL, JS.N(i++)); // push the index in the array to place it into
171 if (peekToken() == COMMA || peekToken() == RB)
172 b.add(parserLine, LITERAL, null); // for stuff like [1,,2,]
174 startExpr(b, NO_COMMA); // push the value onto the stack
175 b.add(parserLine, PUT); // put it into the array
176 b.add(parserLine, POP); // discard the value remaining on the stack
177 if (peekToken() == RB) break;
180 b.set(size0 - 1, JS.N(i)); // back at the ARRAY instruction, write the size of the array
184 case SUB: { // negative literal (like "3 * -1")
186 b.add(parserLine, LITERAL, JS.N(number.doubleValue() * -1));
189 case LP: { // grouping (not calling)
194 case INC: case DEC: { // prefix (not postfix)
195 startExpr(b, precedence[tok]);
196 int prev = b.size - 1;
197 if (b.get(prev) == GET && b.getArg(prev) != null)
198 b.set(prev, LITERAL, b.getArg(prev));
199 else if(b.get(prev) == GET)
202 throw pe("prefixed increment/decrement can only be performed on a valid assignment target");
203 b.add(parserLine, GET_PRESERVE, Boolean.TRUE);
204 b.add(parserLine, LITERAL, JS.N(1));
205 b.add(parserLine, tok == INC ? ADD : SUB, JS.N(2));
206 b.add(parserLine, PUT, null);
207 b.add(parserLine, SWAP, null);
208 b.add(parserLine, POP, null);
211 case BANG: case BITNOT: case TYPEOF: {
212 startExpr(b, precedence[tok]);
213 b.add(parserLine, tok);
216 case LC: { // object constructor
217 b.add(parserLine, OBJECT, null); // put an object on the stack
218 if (peekToken() != RC)
220 if (peekToken() != NAME && peekToken() != STRING)
221 throw pe("expected NAME or STRING");
223 b.add(parserLine, LITERAL, string); // grab the key
225 startExpr(b, NO_COMMA); // grab the value
226 b.add(parserLine, PUT); // put the value into the object
227 b.add(parserLine, POP); // discard the remaining value
228 if (peekToken() == RC) break;
230 if (peekToken() == RC) break; // we permit {,,} -- I'm not sure if ECMA does
236 b.add(parserLine, TOPSCOPE);
237 b.add(parserLine, LITERAL, string);
238 continueExprAfterAssignable(b,minPrecedence);
244 JSFunction b2 = new JSFunction(sourceName, parserLine, null);
245 b.add(parserLine, NEWFUNCTION, b2);
247 // function prelude; arguments array is already on the stack
248 b2.add(parserLine, TOPSCOPE);
249 b2.add(parserLine, SWAP);
250 b2.add(parserLine, DECLARE, "arguments"); // declare arguments (equivalent to 'var arguments;')
251 b2.add(parserLine, SWAP); // set this.arguments and leave the value on the stack
252 b2.add(parserLine, PUT);
254 while(peekToken() != RP) { // run through the list of argument names
256 if (peekToken() == NAME) {
257 consume(NAME); // a named argument
258 String varName = string;
260 b2.add(parserLine, DUP); // dup the args array
261 b2.add(parserLine, GET, JS.N(numArgs - 1)); // retrieve it from the arguments array
262 b2.add(parserLine, TOPSCOPE);
263 b2.add(parserLine, SWAP);
264 b2.add(parserLine, DECLARE, varName); // declare the name
265 b2.add(parserLine, SWAP);
266 b2.add(parserLine, PUT);
267 b2.add(parserLine, POP); // pop the value
268 b2.add(parserLine, POP); // pop the scope
270 if (peekToken() == RP) break;
275 b2.numFormalArgs = numArgs;
276 b2.add(parserLine, POP); // pop off the arguments array
277 b2.add(parserLine, POP); // pop off TOPSCOPE
279 if(peekToken() != LC)
280 throw pe("JSFunctions must have a block surrounded by curly brackets");
282 parseBlock(b2, null); // the function body
284 b2.add(parserLine, LITERAL, null); // in case we "fall out the bottom", return NULL
285 b2.add(parserLine, RETURN);
289 default: throw pe("expected expression, found " + codeToString[tok] + ", which cannot start an expression");
292 // attempt to continue the expression
293 continueExpr(b, minPrecedence);
298 * Assuming that a complete assignable (lvalue) has just been
299 * parsed and the object and key are on the stack,
300 * <tt>continueExprAfterAssignable</tt> will attempt to parse an
301 * expression that modifies the assignable. This method always
302 * decreases the stack depth by exactly one element.
304 private void continueExprAfterAssignable(JSFunction b,int minPrecedence) throws IOException {
305 int saveParserLine = parserLine;
306 _continueExprAfterAssignable(b,minPrecedence);
307 parserLine = saveParserLine;
309 private void _continueExprAfterAssignable(JSFunction b,int minPrecedence) throws IOException {
310 if (b == null) throw new Error("got null b; this should never happen");
311 int tok = getToken();
312 if (minPrecedence != -1 && (precedence[tok] < minPrecedence || (precedence[tok] == minPrecedence && !isRightAssociative[tok])))
313 // force the default case
316 case ASSIGN_BITOR: case ASSIGN_BITXOR: case ASSIGN_BITAND: case ASSIGN_LSH: case ASSIGN_RSH: case ASSIGN_URSH:
317 case ASSIGN_MUL: case ASSIGN_DIV: case ASSIGN_MOD: case ASSIGN_ADD: case ASSIGN_SUB: {
318 b.add(parserLine, GET_PRESERVE);
319 startExpr(b, precedence[tok]);
321 if (tok == ASSIGN_ADD || tok == ASSIGN_SUB) {
322 b.add(parserLine, tok);
324 // tok-1 is always s/^ASSIGN_// (0 is BITOR, 1 is ASSIGN_BITOR, etc)
325 b.add(parserLine, tok - 1, tok-1==ADD ? JS.N(2) : null);
326 b.add(parserLine, PUT);
327 b.add(parserLine, SWAP);
328 b.add(parserLine, POP);
329 if (tok == ASSIGN_ADD || tok == ASSIGN_SUB) b.set(size, tok, JS.N(b.size - size));
332 case INC: case DEC: { // postfix
333 b.add(parserLine, GET_PRESERVE, Boolean.TRUE);
334 b.add(parserLine, LITERAL, JS.N(1));
335 b.add(parserLine, tok == INC ? ADD : SUB, JS.N(2));
336 b.add(parserLine, PUT, null);
337 b.add(parserLine, SWAP, null);
338 b.add(parserLine, POP, null);
339 b.add(parserLine, LITERAL, JS.N(1));
340 b.add(parserLine, tok == INC ? SUB : ADD, null); // undo what we just did, since this is postfix
344 startExpr(b, precedence[tok]);
345 b.add(parserLine, PUT);
346 b.add(parserLine, SWAP);
347 b.add(parserLine, POP);
352 // Method calls are implemented by doing a GET_PRESERVE
353 // first. If the object supports method calls, it will
355 int n = parseArgs(b, 2);
356 b.add(parserLine, GET_PRESERVE);
357 b.add(parserLine, CALLMETHOD, JS.N(n));
362 if(b.get(b.size-1) == LITERAL && b.getArg(b.size-1) != null)
363 b.set(b.size-1,GET,b.getArg(b.size-1));
365 b.add(parserLine, GET);
373 * Assuming that a complete expression has just been parsed,
374 * <tt>continueExpr</tt> will attempt to extend this expression by
375 * parsing additional tokens and appending additional bytecodes.
377 * No operators with precedence less than <tt>minPrecedence</tt>
380 * If any bytecodes are appended, they will not alter the stack
383 private void continueExpr(JSFunction b, int minPrecedence) throws IOException {
384 int saveParserLine = parserLine;
385 _continueExpr(b, minPrecedence);
386 parserLine = saveParserLine;
388 private void _continueExpr(JSFunction b, int minPrecedence) throws IOException {
389 if (b == null) throw new Error("got null b; this should never happen");
390 int tok = getToken();
391 if (tok == -1) return;
392 if (minPrecedence != -1 && (precedence[tok] < minPrecedence || (precedence[tok] == minPrecedence && !isRightAssociative[tok]))) {
398 case LP: { // invocation (not grouping)
399 int n = parseArgs(b, 1);
400 b.add(parserLine, CALL, JS.N(n));
403 case BITOR: case BITXOR: case BITAND: case SHEQ: case SHNE: case LSH:
404 case RSH: case URSH: case MUL: case DIV: case MOD:
405 case GT: case GE: case EQ: case NE: case LT: case LE: case SUB: {
406 startExpr(b, precedence[tok]);
407 b.add(parserLine, tok);
414 startExpr(b,precedence[tok]);
416 nextTok = getToken();
417 } while(nextTok == tok);
419 b.add(parserLine, tok, JS.N(count));
423 b.add(parserLine, tok == AND ? b.JF : b.JT, JS.ZERO); // test to see if we can short-circuit
425 startExpr(b, precedence[tok]); // otherwise check the second value
426 b.add(parserLine, JMP, JS.N(2)); // leave the second value on the stack and jump to the end
427 b.add(parserLine, LITERAL, tok == AND ?
428 JS.B(false) : JS.B(true)); // target of the short-circuit jump is here
429 b.set(size - 1, JS.N(b.size - size)); // write the target of the short-circuit jump
433 // support foo..bar syntax for foo[""].bar
434 if (peekToken() == DOT) {
439 b.add(parserLine, LITERAL, string);
440 continueExprAfterAssignable(b,minPrecedence);
443 case LB: { // subscripting (not array constructor)
446 continueExprAfterAssignable(b,minPrecedence);
450 b.add(parserLine, JF, JS.ZERO); // jump to the if-false expression
452 startExpr(b, minPrecedence); // write the if-true expression
453 b.add(parserLine, JMP, JS.ZERO); // if true, jump *over* the if-false expression
454 b.set(size - 1, JS.N(b.size - size + 1)); // now we know where the target of the jump is
457 startExpr(b, minPrecedence); // write the if-false expression
458 b.set(size - 1, JS.N(b.size - size + 1)); // this is the end; jump to here
462 // pop the result of the previous expression, it is ignored
463 b.add(parserLine,POP);
473 continueExpr(b, minPrecedence); // try to continue the expression
476 // parse a set of comma separated function arguments, assume LP has already been consumed
477 // if swap is true, (because the function is already on the stack) we will SWAP after each argument to keep it on top
478 private int parseArgs(JSFunction b, int pushdown) throws IOException {
480 while(peekToken() != RP) {
482 if (peekToken() != COMMA) {
483 startExpr(b, NO_COMMA);
484 b.add(parserLine, SWAP, JS.N(pushdown));
485 if (peekToken() == RP) break;
493 /** Parse a block of statements which must be surrounded by LC..RC. */
494 void parseBlock(JSFunction b) throws IOException { parseBlock(b, null); }
495 void parseBlock(JSFunction b, String label) throws IOException {
496 int saveParserLine = parserLine;
497 _parseBlock(b, label);
498 parserLine = saveParserLine;
500 void _parseBlock(JSFunction b, String label) throws IOException {
501 if (peekToken() == -1) return;
502 else if (peekToken() != LC) parseStatement(b, null);
505 while(peekToken() != RC && peekToken() != -1) parseStatement(b, null);
510 /** Parse a single statement, consuming the RC or SEMI which terminates it. */
511 void parseStatement(JSFunction b, String label) throws IOException {
512 int saveParserLine = parserLine;
513 _parseStatement(b, label);
514 parserLine = saveParserLine;
516 void _parseStatement(JSFunction b, String label) throws IOException {
517 int tok = peekToken();
518 if (tok == -1) return;
519 switch(tok = getToken()) {
521 case THROW: case ASSERT: case RETURN: {
522 if (tok == RETURN && peekToken() == SEMI)
523 b.add(parserLine, LITERAL, null);
526 b.add(parserLine, tok);
530 case BREAK: case CONTINUE: {
531 if (peekToken() == NAME) consume(NAME);
532 b.add(parserLine, tok, string);
537 b.add(parserLine, TOPSCOPE); // push the current scope
540 b.add(parserLine, DECLARE, string); // declare it
541 if (peekToken() == ASSIGN) { // if there is an '=' after the variable name
543 startExpr(b, NO_COMMA);
544 b.add(parserLine, PUT); // assign it
545 b.add(parserLine, POP); // clean the stack
547 b.add(parserLine, POP); // pop the string pushed by declare
549 if (peekToken() != COMMA) break;
552 b.add(parserLine, POP); // pop off the topscope
553 if ((mostRecentlyReadToken != RC || peekToken() == SEMI) && peekToken() != -1 && mostRecentlyReadToken != SEMI) consume(SEMI);
561 b.add(parserLine, JF, JS.ZERO); // if false, jump to the else-block
563 parseStatement(b, null);
565 if (peekToken() == ELSE) {
567 b.add(parserLine, JMP, JS.ZERO); // if we took the true-block, jump over the else-block
568 b.set(size - 1, JS.N(b.size - size + 1));
570 parseStatement(b, null);
572 b.set(size - 1, JS.N(b.size - size + 1)); // regardless of which branch we took, b[size] needs to point here
577 if (label != null) b.add(parserLine, LABEL, label);
578 b.add(parserLine, LOOP);
580 b.add(parserLine, POP); // discard the first-iteration indicator
582 b.add(parserLine, JT, JS.N(2)); // if the while() clause is true, jump over the BREAK
583 b.add(parserLine, BREAK);
585 parseStatement(b, null);
586 b.add(parserLine, CONTINUE); // if we fall out of the end, definately continue
587 b.set(size - 1, JS.N(b.size - size + 1)); // end of the loop
592 if (label != null) b.add(parserLine, LABEL, label);
593 b.add(parserLine, LOOP);
599 if (peekToken() == CASE) { // we compile CASE statements like a bunch of if..else's
601 b.add(parserLine, DUP); // duplicate the switch() value; we'll consume one copy
604 b.add(parserLine, EQ); // check if we should do this case-block
605 b.add(parserLine, JF, JS.ZERO); // if not, jump to the next one
607 while(peekToken() != CASE && peekToken() != DEFAULT && peekToken() != RC) parseStatement(b, null);
608 b.set(size - 1, JS.N(1 + b.size - size));
609 } else if (peekToken() == DEFAULT) {
612 while(peekToken() != CASE && peekToken() != DEFAULT && peekToken() != RC) parseStatement(b, null);
613 } else if (peekToken() == RC) {
615 b.add(parserLine, BREAK); // break out of the loop if we 'fall through'
618 throw pe("expected CASE, DEFAULT, or RC; got " + codeToString[peekToken()]);
620 b.set(size0 - 1, JS.N(b.size - size0 + 1)); // end of the loop
625 if (label != null) b.add(parserLine, LABEL, label);
626 b.add(parserLine, LOOP);
628 parseStatement(b, null);
632 b.add(parserLine, JT, JS.N(2)); // check the while() clause; jump over the BREAK if true
633 b.add(parserLine, BREAK);
634 b.add(parserLine, CONTINUE);
637 b.set(size - 1, JS.N(b.size - size + 1)); // end of the loop; write this location to the LOOP instruction
642 b.add(parserLine, TRY); // try bytecode causes a TryMarker to be pushed
643 int tryInsn = b.size - 1;
644 // parse the expression to be TRYed
645 parseStatement(b, null);
646 // pop the try marker. this is pushed when the TRY bytecode is executed
647 b.add(parserLine, POP);
648 // jump forward to the end of the catch block, start of the finally block
649 b.add(parserLine, JMP);
650 int successJMPInsn = b.size - 1;
652 if (peekToken() != CATCH && peekToken() != FINALLY)
653 throw pe("try without catch or finally");
655 int catchJMPDistance = -1;
656 if (peekToken() == CATCH) {
657 catchJMPDistance = b.size - tryInsn;
662 exceptionVar = string;
664 b.add(parserLine, TOPSCOPE); // the exception is on top of the stack; put it to the chosen name
665 b.add(parserLine, SWAP);
666 b.add(parserLine, LITERAL,exceptionVar);
667 b.add(parserLine, SWAP);
668 b.add(parserLine, PUT);
669 b.add(parserLine, POP);
670 b.add(parserLine, POP);
671 parseStatement(b, null);
672 // pop the try and catch markers
673 b.add(parserLine,POP);
674 b.add(parserLine,POP);
677 // jump here if no exception was thrown
678 b.set(successJMPInsn, JS.N(b.size - successJMPInsn));
680 int finallyJMPDistance = -1;
681 if (peekToken() == FINALLY) {
682 b.add(parserLine, LITERAL, null); // null FinallyData
683 finallyJMPDistance = b.size - tryInsn;
685 parseStatement(b, null);
686 b.add(parserLine,FINALLY_DONE);
689 // setup the TRY arguments
690 b.set(tryInsn, new int[] { catchJMPDistance, finallyJMPDistance });
699 boolean hadVar = false; // if it's a for..in, we ignore the VAR
700 if (tok == VAR) { hadVar = true; tok = getToken(); }
701 String varName = string;
702 boolean forIn = peekToken() == IN; // determine if this is a for..in loop or not
703 pushBackToken(tok, varName);
706 b.add(parserLine, NEWSCOPE); // for-loops always create new scopes
707 b.add(parserLine, LITERAL, varName); // declare the new variable
708 b.add(parserLine, DECLARE);
710 b.add(parserLine, LOOP); // we actually only add this to ensure that BREAK works
711 b.add(parserLine, POP); // discard the first-iteration indicator
716 b.add(parserLine, PUSHKEYS); // push the keys as an array; check the length
717 b.add(parserLine, LITERAL, "length");
718 b.add(parserLine, GET);
721 b.add(parserLine, LITERAL, JS.N(1)); // decrement the length
722 b.add(parserLine, SUB);
723 b.add(parserLine, DUP);
724 b.add(parserLine, LITERAL, JS.ZERO); // see if we've exhausted all the elements
725 b.add(parserLine, LT);
726 b.add(parserLine, JF, JS.N(2));
727 b.add(parserLine, BREAK); // if we have, then BREAK
728 b.add(parserLine, GET_PRESERVE); // get the key out of the keys array
729 b.add(parserLine, LITERAL, varName);
730 b.add(parserLine, PUT); // write it to this[varName]
731 parseStatement(b, null); // do some stuff
732 b.add(parserLine, CONTINUE); // continue if we fall out the bottom
734 b.set(size - 1, JS.N(b.size - size + 1)); // BREAK to here
735 b.add(parserLine, OLDSCOPE); // restore the scope
738 if (hadVar) pushBackToken(VAR, null); // yeah, this actually matters
739 b.add(parserLine, NEWSCOPE); // grab a fresh scope
741 parseStatement(b, null); // initializer
742 JSFunction e2 = // we need to put the incrementor before the test
743 new JSFunction(sourceName, parserLine, null); // so we save the test here
744 if (peekToken() != SEMI)
747 e2.add(parserLine, b.LITERAL, Boolean.TRUE); // handle the for(foo;;foo) case
749 if (label != null) b.add(parserLine, LABEL, label);
750 b.add(parserLine, LOOP);
753 b.add(parserLine, JT, JS.ZERO); // if we're on the first iteration, jump over the incrementor
755 if (peekToken() != RP) { // do the increment thing
757 b.add(parserLine, POP);
759 b.set(size - 1, JS.N(b.size - size + 1));
762 b.paste(e2); // ok, *now* test if we're done yet
763 b.add(parserLine, JT, JS.N(2)); // break out if we don't meet the test
764 b.add(parserLine, BREAK);
765 parseStatement(b, null);
766 b.add(parserLine, CONTINUE); // if we fall out the bottom, CONTINUE
767 b.set(size2 - 1, JS.N(b.size - size2 + 1)); // end of the loop
769 b.add(parserLine, OLDSCOPE); // get our scope back
774 case NAME: { // either a label or an identifier; this is the one place we're not LL(1)
775 String possiblyTheLabel = string;
776 if (peekToken() == COLON) { // label
778 parseStatement(b, possiblyTheLabel);
780 } else { // expression
781 pushBackToken(NAME, possiblyTheLabel);
783 b.add(parserLine, POP);
784 if ((mostRecentlyReadToken != RC || peekToken() == SEMI) && peekToken() != -1 && mostRecentlyReadToken != SEMI) consume(SEMI);
789 case SEMI: return; // yep, the null statement is valid
791 case LC: { // blocks are statements too
793 b.add(parserLine, NEWSCOPE);
794 parseBlock(b, label);
795 b.add(parserLine, OLDSCOPE);
799 default: { // hope that it's an expression
802 b.add(parserLine, POP);
803 if ((mostRecentlyReadToken != RC || peekToken() == SEMI) && peekToken() != -1 && mostRecentlyReadToken != SEMI) consume(SEMI);
810 // ParserException //////////////////////////////////////////////////////////////////////
811 private IOException pe(String s) { return new IOException(sourceName + ":" + parserLine + " " + s); }