forked from mishoo/UglifyJS
/
compress.js
6946 lines (6724 loc) · 291 KB
/
compress.js
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
824
825
826
827
828
829
830
831
832
833
834
835
836
837
838
839
840
841
842
843
844
845
846
847
848
849
850
851
852
853
854
855
856
857
858
859
860
861
862
863
864
865
866
867
868
869
870
871
872
873
874
875
876
877
878
879
880
881
882
883
884
885
886
887
888
889
890
891
892
893
894
895
896
897
898
899
900
901
902
903
904
905
906
907
908
909
910
911
912
913
914
915
916
917
918
919
920
921
922
923
924
925
926
927
928
929
930
931
932
933
934
935
936
937
938
939
940
941
942
943
944
945
946
947
948
949
950
951
952
953
954
955
956
957
958
959
960
961
962
963
964
965
966
967
968
969
970
971
972
973
974
975
976
977
978
979
980
981
982
983
984
985
986
987
988
989
990
991
992
993
994
995
996
997
998
999
1000
/***********************************************************************
A JavaScript tokenizer / parser / beautifier / compressor.
https://github.com/mishoo/UglifyJS2
-------------------------------- (C) ---------------------------------
Author: Mihai Bazon
<mihai.bazon@gmail.com>
http://mihai.bazon.net/blog
Distributed under the BSD license:
Copyright 2012 (c) Mihai Bazon <mihai.bazon@gmail.com>
Redistribution and use in source and binary forms, with or without
modification, are permitted provided that the following conditions
are met:
* Redistributions of source code must retain the above
copyright notice, this list of conditions and the following
disclaimer.
* Redistributions in binary form must reproduce the above
copyright notice, this list of conditions and the following
disclaimer in the documentation and/or other materials
provided with the distribution.
THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDER “AS IS” AND ANY
EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER BE
LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY,
OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR
TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF
THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
SUCH DAMAGE.
***********************************************************************/
"use strict";
function Compressor(options, false_by_default) {
if (!(this instanceof Compressor))
return new Compressor(options, false_by_default);
TreeTransformer.call(this, this.before, this.after);
this.options = defaults(options, {
arguments : !false_by_default,
assignments : !false_by_default,
booleans : !false_by_default,
collapse_vars : !false_by_default,
comparisons : !false_by_default,
conditionals : !false_by_default,
dead_code : !false_by_default,
directives : !false_by_default,
drop_console : false,
drop_debugger : !false_by_default,
evaluate : !false_by_default,
expression : false,
functions : !false_by_default,
global_defs : false,
hoist_funs : false,
hoist_props : !false_by_default,
hoist_vars : false,
ie8 : false,
if_return : !false_by_default,
inline : !false_by_default,
join_vars : !false_by_default,
keep_fargs : false_by_default || "strict",
keep_fnames : false,
keep_infinity : false,
loops : !false_by_default,
negate_iife : !false_by_default,
passes : 1,
properties : !false_by_default,
pure_getters : !false_by_default && "strict",
pure_funcs : null,
reduce_funcs : !false_by_default,
reduce_vars : !false_by_default,
sequences : !false_by_default,
side_effects : !false_by_default,
switches : !false_by_default,
top_retain : null,
toplevel : !!(options && options["top_retain"]),
typeofs : !false_by_default,
unsafe : false,
unsafe_comps : false,
unsafe_Function : false,
unsafe_math : false,
unsafe_proto : false,
unsafe_regexp : false,
unsafe_undefined: false,
unused : !false_by_default,
}, true);
var global_defs = this.options["global_defs"];
if (typeof global_defs == "object") for (var key in global_defs) {
if (/^@/.test(key) && HOP(global_defs, key)) {
global_defs[key.slice(1)] = parse(global_defs[key], {
expression: true
});
}
}
if (this.options["inline"] === true) this.options["inline"] = 3;
var keep_fargs = this.options["keep_fargs"];
this.drop_fargs = keep_fargs == "strict" ? function(lambda, parent) {
if (lambda.length_read) return false;
var name = lambda.name;
if (!name) return parent && parent.TYPE == "Call" && parent.expression === lambda;
if (name.fixed_value() !== lambda) return false;
var def = name.definition();
if (def.direct_access) return false;
var escaped = def.escaped;
return escaped && escaped.depth != 1;
} : keep_fargs ? return_false : return_true;
var pure_funcs = this.options["pure_funcs"];
if (typeof pure_funcs == "function") {
this.pure_funcs = pure_funcs;
} else if (typeof pure_funcs == "string") {
this.pure_funcs = function(node) {
return pure_funcs !== node.expression.print_to_string();
};
} else if (Array.isArray(pure_funcs)) {
this.pure_funcs = function(node) {
return !member(node.expression.print_to_string(), pure_funcs);
};
} else {
this.pure_funcs = return_true;
}
var sequences = this.options["sequences"];
this.sequences_limit = sequences == 1 ? 800 : sequences | 0;
var top_retain = this.options["top_retain"];
if (top_retain instanceof RegExp) {
this.top_retain = function(def) {
return top_retain.test(def.name);
};
} else if (typeof top_retain == "function") {
this.top_retain = top_retain;
} else if (top_retain) {
if (typeof top_retain == "string") {
top_retain = top_retain.split(/,/);
}
this.top_retain = function(def) {
return member(def.name, top_retain);
};
}
var toplevel = this.options["toplevel"];
this.toplevel = typeof toplevel == "string" ? {
funcs: /funcs/.test(toplevel),
vars: /vars/.test(toplevel)
} : {
funcs: toplevel,
vars: toplevel
};
}
Compressor.prototype = new TreeTransformer;
merge(Compressor.prototype, {
option: function(key) { return this.options[key] },
exposed: function(def) {
if (def.global) for (var i = 0; i < def.orig.length; i++)
if (!this.toplevel[def.orig[i] instanceof AST_SymbolDefun ? "funcs" : "vars"])
return true;
return false;
},
compress: function(node) {
node = node.resolve_defines(this);
if (this.option("expression")) {
node.process_expression(true);
}
var passes = +this.options.passes || 1;
var min_count = 1 / 0;
var stopping = false;
var mangle = { ie8: this.option("ie8") };
for (var pass = 0; pass < passes; pass++) {
node.figure_out_scope(mangle);
if (pass > 0 || this.option("reduce_vars"))
node.reset_opt_flags(this);
node = node.transform(this);
if (passes > 1) {
var count = 0;
node.walk(new TreeWalker(function() {
count++;
}));
AST_Node.info("pass " + pass + ": last_count: " + min_count + ", count: " + count);
if (count < min_count) {
min_count = count;
stopping = false;
} else if (stopping) {
break;
} else {
stopping = true;
}
}
}
if (this.option("expression")) {
node.process_expression(false);
}
return node;
},
before: function(node, descend, in_list) {
if (node._squeezed) return node;
var is_scope = node instanceof AST_Scope;
if (is_scope) {
node.hoist_properties(this);
node.hoist_declarations(this);
}
// Before https://github.com/mishoo/UglifyJS2/pull/1602 AST_Node.optimize()
// would call AST_Node.transform() if a different instance of AST_Node is
// produced after OPT().
// This corrupts TreeWalker.stack, which cause AST look-ups to malfunction.
// Migrate and defer all children's AST_Node.transform() to below, which
// will now happen after this parent AST_Node has been properly substituted
// thus gives a consistent AST snapshot.
descend(node, this);
// Existing code relies on how AST_Node.optimize() worked, and omitting the
// following replacement call would result in degraded efficiency of both
// output and performance.
descend(node, this);
var opt = node.optimize(this);
if (is_scope) {
opt.drop_unused(this);
descend(opt, this);
}
if (opt === node) opt._squeezed = true;
return opt;
}
});
(function(OPT) {
OPT(AST_Node, function(self, compressor) {
return self;
});
AST_Node.DEFMETHOD("equivalent_to", function(node) {
return this.TYPE == node.TYPE && this.print_to_string() == node.print_to_string();
});
AST_Scope.DEFMETHOD("process_expression", function(insert, compressor) {
var self = this;
var tt = new TreeTransformer(function(node) {
if (insert && node instanceof AST_SimpleStatement) {
return make_node(AST_Return, node, {
value: node.body
});
}
if (!insert && node instanceof AST_Return) {
if (compressor) {
var value = node.value && node.value.drop_side_effect_free(compressor, true);
return value ? make_node(AST_SimpleStatement, node, {
body: value
}) : make_node(AST_EmptyStatement, node);
}
return make_node(AST_SimpleStatement, node, {
body: node.value || make_node(AST_UnaryPrefix, node, {
operator: "void",
expression: make_node(AST_Number, node, {
value: 0
})
})
});
}
if (node instanceof AST_Lambda && node !== self) {
return node;
}
if (node instanceof AST_Block) {
var index = node.body.length - 1;
if (index >= 0) {
node.body[index] = node.body[index].transform(tt);
}
} else if (node instanceof AST_If) {
node.body = node.body.transform(tt);
if (node.alternative) {
node.alternative = node.alternative.transform(tt);
}
} else if (node instanceof AST_With) {
node.body = node.body.transform(tt);
}
return node;
});
self.transform(tt);
});
function read_property(obj, node) {
var key = node.getProperty();
if (key instanceof AST_Node) return;
var value;
if (obj instanceof AST_Array) {
var elements = obj.elements;
if (key == "length") return make_node_from_constant(elements.length, obj);
if (typeof key == "number" && key in elements) value = elements[key];
} else if (obj instanceof AST_Lambda) {
if (key == "length") {
obj.length_read = true;
return make_node_from_constant(obj.argnames.length, obj);
}
} else if (obj instanceof AST_Object) {
key = "" + key;
var props = obj.properties;
for (var i = props.length; --i >= 0;) {
var prop = props[i];
if (!(prop instanceof AST_ObjectKeyVal)) return;
if (!value && props[i].key === key) value = props[i].value;
}
}
return value instanceof AST_SymbolRef && value.fixed_value() || value;
}
function is_read_only_fn(value, name) {
if (value instanceof AST_Boolean) return native_fns.Boolean[name];
if (value instanceof AST_Number) return native_fns.Number[name];
if (value instanceof AST_String) return native_fns.String[name];
if (name == "valueOf") return false;
if (value instanceof AST_Array) return native_fns.Array[name];
if (value instanceof AST_Function) return native_fns.Function[name];
if (value instanceof AST_Object) return native_fns.Object[name];
if (value instanceof AST_RegExp) return native_fns.RegExp[name];
}
function is_modified(compressor, tw, node, value, level, immutable) {
var parent = tw.parent(level);
if (compressor.option("unsafe") && parent instanceof AST_Dot && is_read_only_fn(value, parent.property)) {
return;
}
var lhs = is_lhs(node, parent);
if (lhs) return lhs;
if (!immutable
&& parent instanceof AST_Call
&& parent.expression === node
&& !parent.is_expr_pure(compressor)
&& (!(value instanceof AST_Function)
|| !(parent instanceof AST_New) && value.contains_this())) {
return true;
}
if (parent instanceof AST_Array) {
return is_modified(compressor, tw, parent, parent, level + 1);
}
if (parent instanceof AST_ObjectKeyVal && node === parent.value) {
var obj = tw.parent(level + 1);
return is_modified(compressor, tw, obj, obj, level + 2);
}
if (parent instanceof AST_PropAccess && parent.expression === node) {
var prop = read_property(value, parent);
return !immutable && is_modified(compressor, tw, parent, prop, level + 1);
}
}
function is_arguments(def) {
if (def.name != "arguments") return false;
var orig = def.orig;
return orig.length == 1 && orig[0] instanceof AST_SymbolFunarg;
}
(function(def) {
def(AST_Node, noop);
function reset_def(tw, compressor, def) {
def.assignments = 0;
def.chained = false;
def.direct_access = false;
def.escaped = [];
def.fixed = !def.scope.pinned()
&& !compressor.exposed(def)
&& !(def.init instanceof AST_Function && def.init !== def.scope)
&& def.init;
if (def.fixed instanceof AST_Defun && !all(def.references, function(ref) {
var scope = ref.scope;
do {
if (def.scope === scope) return true;
} while (scope instanceof AST_Function && (scope = scope.parent_scope));
})) {
tw.defun_ids[def.id] = false;
}
def.recursive_refs = 0;
def.references = [];
def.should_replace = undefined;
def.single_use = undefined;
}
function reset_variables(tw, compressor, scope) {
scope.variables.each(function(def) {
reset_def(tw, compressor, def);
if (def.fixed === null) {
def.safe_ids = tw.safe_ids;
mark(tw, def, true);
} else if (def.fixed) {
tw.loop_ids[def.id] = tw.in_loop;
mark(tw, def, true);
}
});
scope.may_call_this = function() {
scope.may_call_this = noop;
if (!scope.contains_this()) return;
scope.functions.each(function(def) {
if (def.init instanceof AST_Defun && !(def.id in tw.defun_ids)) {
tw.defun_ids[def.id] = false;
}
});
};
}
function mark_defun(tw, def) {
if (def.id in tw.defun_ids) {
var marker = tw.defun_ids[def.id];
if (!marker) return;
var visited = tw.defun_visited[def.id];
if (marker === tw.safe_ids) {
if (!visited) return def.fixed;
} else if (visited) {
def.init.enclosed.forEach(function(d) {
if (def.init.variables.get(d.name) === d) return;
if (!safe_to_read(tw, d)) d.fixed = false;
});
} else {
tw.defun_ids[def.id] = false;
}
} else {
if (!tw.in_loop) {
tw.defun_ids[def.id] = tw.safe_ids;
return def.fixed;
}
tw.defun_ids[def.id] = false;
}
}
function walk_defuns(tw, scope) {
scope.functions.each(function(def) {
if (def.init instanceof AST_Defun && !tw.defun_visited[def.id]) {
tw.defun_ids[def.id] = tw.safe_ids;
def.init.walk(tw);
}
});
}
function push(tw) {
tw.safe_ids = Object.create(tw.safe_ids);
}
function pop(tw) {
tw.safe_ids = Object.getPrototypeOf(tw.safe_ids);
}
function mark(tw, def, safe) {
tw.safe_ids[def.id] = safe;
}
function safe_to_read(tw, def) {
if (def.single_use == "m") return false;
if (tw.safe_ids[def.id]) {
if (def.fixed == null) {
if (is_arguments(def)) return false;
if (def.global && def.name == "arguments") return false;
def.fixed = make_node(AST_Undefined, def.orig);
}
return true;
}
return def.fixed instanceof AST_Defun;
}
function safe_to_assign(tw, def, scope, value) {
if (def.fixed === undefined) return true;
if (def.fixed === null && def.safe_ids) {
def.safe_ids[def.id] = false;
delete def.safe_ids;
return true;
}
if (!HOP(tw.safe_ids, def.id)) return false;
if (!safe_to_read(tw, def)) return false;
if (def.fixed === false) return false;
if (def.fixed != null && (!value || def.references.length > def.assignments)) return false;
if (def.fixed instanceof AST_Defun) {
return value instanceof AST_Node && def.fixed.parent_scope === scope;
}
return all(def.orig, function(sym) {
return !(sym instanceof AST_SymbolDefun || sym instanceof AST_SymbolLambda);
});
}
function ref_once(tw, compressor, def) {
return compressor.option("unused")
&& !def.scope.pinned()
&& def.references.length - def.recursive_refs == 1
&& tw.loop_ids[def.id] === tw.in_loop;
}
function is_immutable(value) {
if (!value) return false;
return value.is_constant()
|| value instanceof AST_Lambda
|| value instanceof AST_This;
}
function mark_escaped(tw, d, scope, node, value, level, depth) {
var parent = tw.parent(level);
if (value && value.is_constant()) return;
if (parent instanceof AST_Assign && parent.operator == "=" && node === parent.right
|| parent instanceof AST_Call && (node !== parent.expression || parent instanceof AST_New)
|| parent instanceof AST_Exit && node === parent.value && node.scope !== d.scope
|| parent instanceof AST_VarDef && node === parent.value) {
d.escaped.push(parent);
if (depth > 1 && !(value && value.is_constant_expression(scope))) depth = 1;
if (!d.escaped.depth || d.escaped.depth > depth) d.escaped.depth = depth;
return;
} else if (parent instanceof AST_Array
|| parent instanceof AST_Binary && lazy_op[parent.operator]
|| parent instanceof AST_Conditional && node !== parent.condition
|| parent instanceof AST_Sequence && node === parent.tail_node()) {
mark_escaped(tw, d, scope, parent, parent, level + 1, depth);
} else if (parent instanceof AST_ObjectKeyVal && node === parent.value) {
var obj = tw.parent(level + 1);
mark_escaped(tw, d, scope, obj, obj, level + 2, depth);
} else if (parent instanceof AST_PropAccess && node === parent.expression) {
value = read_property(value, parent);
mark_escaped(tw, d, scope, parent, value, level + 1, depth + 1);
if (value) return;
}
if (level > 0) return;
if (parent instanceof AST_Call && node === parent.expression) return;
if (parent instanceof AST_Sequence && node !== parent.tail_node()) return;
if (parent instanceof AST_SimpleStatement) return;
if (parent instanceof AST_Unary && !unary_side_effects[parent.operator]) return;
d.direct_access = true;
}
function mark_assignment_to_arguments(node) {
if (!(node instanceof AST_Sub)) return;
var expr = node.expression;
if (!(expr instanceof AST_SymbolRef)) return;
var def = expr.definition();
if (is_arguments(def) && node.property instanceof AST_Number) def.reassigned = true;
}
var suppressor = new TreeWalker(function(node) {
if (!(node instanceof AST_Symbol)) return;
var d = node.definition();
if (!d) return;
if (node instanceof AST_SymbolRef) d.references.push(node);
d.fixed = false;
});
def(AST_Accessor, function(tw, descend, compressor) {
push(tw);
reset_variables(tw, compressor, this);
descend();
pop(tw);
walk_defuns(tw, this);
return true;
});
def(AST_Assign, function(tw, descend, compressor) {
var node = this;
var sym = node.left;
if (!(sym instanceof AST_SymbolRef)) {
mark_assignment_to_arguments(sym);
return;
}
if (sym.fixed) delete sym.fixed;
var d = sym.definition();
var safe = safe_to_assign(tw, d, sym.scope, node.right);
d.assignments++;
var fixed = d.fixed;
if (!fixed && node.operator != "=") return;
var eq = node.operator == "=";
var value = eq ? node.right : node;
if (is_modified(compressor, tw, node, value, 0)) return;
if (!eq) d.chained = true;
sym.fixed = d.fixed = eq ? function() {
return node.right;
} : function() {
return make_node(AST_Binary, node, {
operator: node.operator.slice(0, -1),
left: fixed instanceof AST_Node ? fixed : fixed(),
right: node.right
});
};
if (!safe) return;
d.references.push(sym);
mark(tw, d, false);
node.right.walk(tw);
mark(tw, d, true);
if (eq) mark_escaped(tw, d, sym.scope, node, value, 0, 1);
return true;
});
def(AST_Binary, function(tw) {
if (!lazy_op[this.operator]) return;
this.left.walk(tw);
push(tw);
this.right.walk(tw);
pop(tw);
return true;
});
def(AST_Call, function(tw, descend) {
tw.find_parent(AST_Scope).may_call_this();
var exp = this.expression;
if (!(exp instanceof AST_SymbolRef)) return;
var def = exp.definition();
if (!(def.fixed instanceof AST_Defun)) return;
var defun = mark_defun(tw, def);
if (!defun) return;
descend();
defun.walk(tw);
return true;
});
def(AST_Case, function(tw) {
push(tw);
this.expression.walk(tw);
pop(tw);
push(tw);
walk_body(this, tw);
pop(tw);
return true;
});
def(AST_Conditional, function(tw) {
this.condition.walk(tw);
push(tw);
this.consequent.walk(tw);
pop(tw);
push(tw);
this.alternative.walk(tw);
pop(tw);
return true;
});
def(AST_Default, function(tw, descend) {
push(tw);
descend();
pop(tw);
return true;
});
def(AST_Defun, function(tw, descend, compressor) {
var id = this.name.definition().id;
if (tw.defun_visited[id]) return true;
if (tw.defun_ids[id] !== tw.safe_ids) return true;
tw.defun_visited[id] = true;
this.inlined = false;
push(tw);
reset_variables(tw, compressor, this);
descend();
pop(tw);
walk_defuns(tw, this);
return true;
});
def(AST_Do, function(tw) {
var saved_loop = tw.in_loop;
tw.in_loop = this;
push(tw);
this.body.walk(tw);
if (has_break_or_continue(this)) {
pop(tw);
push(tw);
}
this.condition.walk(tw);
pop(tw);
tw.in_loop = saved_loop;
return true;
});
def(AST_For, function(tw) {
if (this.init) this.init.walk(tw);
var saved_loop = tw.in_loop;
tw.in_loop = this;
push(tw);
if (this.condition) this.condition.walk(tw);
this.body.walk(tw);
if (this.step) {
if (has_break_or_continue(this)) {
pop(tw);
push(tw);
}
this.step.walk(tw);
}
pop(tw);
tw.in_loop = saved_loop;
return true;
});
def(AST_ForIn, function(tw) {
this.init.walk(suppressor);
this.object.walk(tw);
var saved_loop = tw.in_loop;
tw.in_loop = this;
push(tw);
this.body.walk(tw);
pop(tw);
tw.in_loop = saved_loop;
return true;
});
def(AST_Function, function(tw, descend, compressor) {
var node = this;
node.inlined = false;
push(tw);
reset_variables(tw, compressor, node);
var iife;
if (!node.name
&& (iife = tw.parent()) instanceof AST_Call
&& iife.expression === node) {
// Virtually turn IIFE parameters into variable definitions:
// (function(a,b) {...})(c,d) => (function() {var a=c,b=d; ...})()
// So existing transformation rules can work on them.
node.argnames.forEach(function(arg, i) {
var d = arg.definition();
if (d.fixed === undefined && (!node.uses_arguments || tw.has_directive("use strict"))) {
d.fixed = function() {
return iife.args[i] || make_node(AST_Undefined, iife);
};
tw.loop_ids[d.id] = tw.in_loop;
mark(tw, d, true);
} else {
d.fixed = false;
}
});
}
descend();
pop(tw);
walk_defuns(tw, node);
return true;
});
def(AST_If, function(tw) {
this.condition.walk(tw);
push(tw);
this.body.walk(tw);
pop(tw);
if (this.alternative) {
push(tw);
this.alternative.walk(tw);
pop(tw);
}
return true;
});
def(AST_LabeledStatement, function(tw) {
push(tw);
this.body.walk(tw);
pop(tw);
return true;
});
def(AST_SymbolCatch, function() {
this.definition().fixed = false;
});
def(AST_SymbolRef, function(tw, descend, compressor) {
if (this.fixed) delete this.fixed;
var d = this.definition();
d.references.push(this);
if (d.references.length == 1
&& !d.fixed
&& d.orig[0] instanceof AST_SymbolDefun) {
tw.loop_ids[d.id] = tw.in_loop;
}
var value;
if (d.fixed === undefined || !safe_to_read(tw, d)) {
d.fixed = false;
} else if (d.fixed) {
value = this.fixed_value();
if (recursive_ref(tw, d)) {
d.recursive_refs++;
} else if (value && ref_once(tw, compressor, d)) {
d.single_use = value instanceof AST_Lambda && !value.pinned()
|| d.scope === this.scope && value.is_constant_expression();
} else {
d.single_use = false;
}
if (is_modified(compressor, tw, this, value, 0, is_immutable(value))) {
if (d.single_use) {
d.single_use = "m";
} else {
d.fixed = false;
}
}
mark_escaped(tw, d, this.scope, this, value, 0, 1);
}
var parent;
if (d.fixed instanceof AST_Defun
&& !((parent = tw.parent()) instanceof AST_Call && parent.expression === this)) {
var defun = mark_defun(tw, d);
if (defun) defun.walk(tw);
}
});
def(AST_Toplevel, function(tw, descend, compressor) {
this.globals.each(function(def) {
reset_def(tw, compressor, def);
});
push(tw);
reset_variables(tw, compressor, this);
descend();
pop(tw);
walk_defuns(tw, this);
return true;
});
def(AST_Try, function(tw) {
push(tw);
walk_body(this, tw);
pop(tw);
if (this.bcatch) {
push(tw);
this.bcatch.walk(tw);
pop(tw);
}
if (this.bfinally) this.bfinally.walk(tw);
return true;
});
def(AST_Unary, function(tw, descend) {
var node = this;
if (!unary_arithmetic[node.operator]) return;
var exp = node.expression;
if (!(exp instanceof AST_SymbolRef)) {
mark_assignment_to_arguments(exp);
return;
}
if (exp.fixed) delete exp.fixed;
var d = exp.definition();
var safe = safe_to_assign(tw, d, exp.scope, true);
d.assignments++;
var fixed = d.fixed;
if (!fixed) return;
d.chained = true;
exp.fixed = d.fixed = function() {
return make_node(AST_Binary, node, {
operator: node.operator.slice(0, -1),
left: make_node(AST_UnaryPrefix, node, {
operator: "+",
expression: fixed instanceof AST_Node ? fixed : fixed()
}),
right: make_node(AST_Number, node, {
value: 1
})
});
};
if (!safe) return;
d.references.push(exp);
mark(tw, d, true);
return true;
});
def(AST_VarDef, function(tw, descend) {
var node = this;
var d = node.name.definition();
if (node.value) {
if (safe_to_assign(tw, d, node.name.scope, node.value)) {
d.fixed = function() {
return node.value;
};
tw.loop_ids[d.id] = tw.in_loop;
mark(tw, d, false);
descend();
mark(tw, d, true);
return true;
} else {
d.fixed = false;
}
}
});
def(AST_While, function(tw, descend) {
var saved_loop = tw.in_loop;
tw.in_loop = this;
push(tw);
descend();
pop(tw);
tw.in_loop = saved_loop;
return true;
});
})(function(node, func) {
node.DEFMETHOD("reduce_vars", func);
});
AST_Toplevel.DEFMETHOD("reset_opt_flags", function(compressor) {
var tw = new TreeWalker(compressor.option("reduce_vars") ? function(node, descend) {
node._squeezed = false;
node._optimized = false;
return node.reduce_vars(tw, descend, compressor);
} : function(node) {
node._squeezed = false;
node._optimized = false;
});
// Flow control for visiting `AST_Defun`s
tw.defun_ids = Object.create(null);
tw.defun_visited = Object.create(null);
// Record the loop body in which `AST_SymbolDeclaration` is first encountered
tw.in_loop = null;
tw.loop_ids = Object.create(null);
// Stack of look-up tables to keep track of whether a `SymbolDef` has been
// properly assigned before use:
// - `push()` & `pop()` when visiting conditional branches
// - backup & restore via `save_ids` when visiting out-of-order sections
tw.safe_ids = Object.create(null);
this.walk(tw);
});
AST_Symbol.DEFMETHOD("fixed_value", function(final) {
var fixed = this.definition().fixed;
if (!fixed) return fixed;
if (!final && this.fixed) fixed = this.fixed;
return fixed instanceof AST_Node ? fixed : fixed();
});
AST_SymbolRef.DEFMETHOD("is_immutable", function() {
var orig = this.definition().orig;
return orig.length == 1 && orig[0] instanceof AST_SymbolLambda;
});
function is_lhs_read_only(lhs, compressor) {
if (lhs instanceof AST_This) return true;
if (lhs instanceof AST_SymbolRef) {
var def = lhs.definition();
return def.orig[0] instanceof AST_SymbolLambda
|| compressor.exposed(def) && identifier_atom[def.name];
}
if (lhs instanceof AST_PropAccess) {
lhs = lhs.expression;
if (lhs instanceof AST_SymbolRef) {
if (lhs.is_immutable()) return false;
lhs = lhs.fixed_value();
}
if (!lhs) return true;
if (lhs.is_constant()) return true;
return is_lhs_read_only(lhs, compressor);
}
return false;
}
function find_variable(compressor, name) {
var scope, i = 0;
while (scope = compressor.parent(i++)) {
if (scope instanceof AST_Scope) break;
if (scope instanceof AST_Catch) {
scope = scope.argname.definition().scope;
break;
}
}
return scope.find_variable(name);
}
function make_node(ctor, orig, props) {
if (!props) props = {};
if (orig) {
if (!props.start) props.start = orig.start;
if (!props.end) props.end = orig.end;
}
return new ctor(props);
}
function make_sequence(orig, expressions) {
if (expressions.length == 1) return expressions[0];
return make_node(AST_Sequence, orig, {
expressions: expressions.reduce(merge_sequence, [])
});
}
function make_node_from_constant(val, orig) {
switch (typeof val) {
case "string":
return make_node(AST_String, orig, {
value: val
});
case "number":
if (isNaN(val)) return make_node(AST_NaN, orig);
if (isFinite(val)) {
return 1 / val < 0 ? make_node(AST_UnaryPrefix, orig, {
operator: "-",
expression: make_node(AST_Number, orig, { value: -val })
}) : make_node(AST_Number, orig, { value: val });
}
return val < 0 ? make_node(AST_UnaryPrefix, orig, {
operator: "-",
expression: make_node(AST_Infinity, orig)
}) : make_node(AST_Infinity, orig);
case "boolean":
return make_node(val ? AST_True : AST_False, orig);
case "undefined":
return make_node(AST_Undefined, orig);
default:
if (val === null) {
return make_node(AST_Null, orig, { value: null });
}
if (val instanceof RegExp) {
return make_node(AST_RegExp, orig, { value: val });
}
throw new Error(string_template("Can't handle constant of type: {type}", {
type: typeof val
}));
}
}
function needs_unbinding(compressor, val) {
return val instanceof AST_PropAccess
|| compressor.has_directive("use strict")
&& is_undeclared_ref(val)
&& val.name == "eval";
}
// we shouldn't compress (1,func)(something) to
// func(something) because that changes the meaning of
// the func (becomes lexical instead of global).
function maintain_this_binding(compressor, parent, orig, val) {
if (parent instanceof AST_UnaryPrefix && parent.operator == "delete"
|| parent.TYPE == "Call" && parent.expression === orig && needs_unbinding(compressor, val)) {
return make_sequence(orig, [ make_node(AST_Number, orig, { value: 0 }), val ]);
}
return val;
}
function merge_sequence(array, node) {
if (node instanceof AST_Sequence) {
array.push.apply(array, node.expressions);
} else {
array.push(node);