MIRROR: javascript for 🐜's, a tiny runtime with big ambitions
prevent blowing up memory with loop block scope management
+89
-8
+89
-8
src/ant.c
+89
-8
src/ant.c
···
4604
4604
static void mkscope(struct js *js) { (void)js_mkscope(js); }
4605
4605
static void delscope(struct js *js) { (void)js_delscope(js); }
4606
4606
4607
+
static void scope_clear_props(struct js *js, jsval_t scope) {
4608
+
jsoff_t off = (jsoff_t)vdata(scope);
4609
+
jsoff_t header = loadoff(js, off);
4610
+
jsoff_t parent = loadoff(js, off + sizeof(jsoff_t));
4611
+
4612
+
saveoff(js, off, (header & FLAGMASK) | T_OBJ);
4613
+
saveoff(js, off + sizeof(jsoff_t), parent);
4614
+
}
4615
+
4616
+
static bool block_needs_scope(struct js *js) {
4617
+
jsoff_t pos = js->pos, toff = js->toff, tlen = js->tlen;
4618
+
uint8_t tok = js->tok, consumed = js->consumed;
4619
+
bool had_newline = js->had_newline;
4620
+
4621
+
bool needs = false;
4622
+
int depth = 1;
4623
+
js->consumed = 1;
4624
+
4625
+
while (depth > 0) {
4626
+
uint8_t t = next(js);
4627
+
if (t == TOK_EOF) break;
4628
+
if (t == TOK_LBRACE) { depth++; js->consumed = 1; continue; }
4629
+
if (t == TOK_RBRACE) { depth--; js->consumed = 1; continue; }
4630
+
if (depth == 1 && (t == TOK_LET || t == TOK_CONST || t == TOK_CLASS)) { needs = true; break; }
4631
+
js->consumed = 1;
4632
+
}
4633
+
4634
+
js->pos = pos; js->toff = toff; js->tlen = tlen;
4635
+
js->tok = tok; js->consumed = consumed; js->had_newline = had_newline;
4636
+
4637
+
return needs;
4638
+
}
4639
+
4607
4640
static inline bool push_this(jsval_t this_value) {
4608
4641
if (global_this_stack.depth >= global_this_stack.capacity) {
4609
4642
int new_capacity = global_this_stack.capacity == 0 ? 16 : global_this_stack.capacity * 2;
···
4813
4846
4814
4847
static jsval_t js_block(struct js *js, bool create_scope) {
4815
4848
jsval_t res = js_mkundef();
4816
-
if (create_scope) mkscope(js);
4849
+
bool scope_created = false;
4850
+
4851
+
if (create_scope && lookahead(js) != TOK_RBRACE && block_needs_scope(js)) {
4852
+
mkscope(js);
4853
+
scope_created = true;
4854
+
}
4817
4855
4818
4856
js->consumed = 1;
4819
4857
hoist_function_declarations(js);
···
4829
4867
}
4830
4868
4831
4869
if (js->tok == TOK_RBRACE) js->consumed = 1;
4832
-
if (create_scope) delscope(js);
4870
+
if (scope_created) delscope(js);
4833
4871
4834
4872
return res;
4835
4873
}
···
10018
10056
return res;
10019
10057
}
10020
10058
10059
+
typedef struct {
10060
+
bool is_block;
10061
+
bool needs_scope;
10062
+
jsval_t loop_scope;
10063
+
} loop_block_ctx_t;
10064
+
10065
+
static void loop_block_init(struct js *js, loop_block_ctx_t *ctx) {
10066
+
ctx->is_block = (lookahead(js) == TOK_LBRACE);
10067
+
ctx->needs_scope = false;
10068
+
ctx->loop_scope = js_mkundef();
10069
+
10070
+
if (ctx->is_block && !(js->flags & F_NOEXEC)) {
10071
+
jsoff_t saved_pos = js->pos;
10072
+
uint8_t saved_tok = js->tok;
10073
+
uint8_t saved_consumed = js->consumed;
10074
+
10075
+
js->consumed = 1;
10076
+
next(js);
10077
+
ctx->needs_scope = block_needs_scope(js);
10078
+
10079
+
js->pos = saved_pos;
10080
+
js->tok = saved_tok;
10081
+
js->consumed = saved_consumed;
10082
+
10083
+
if (ctx->needs_scope) ctx->loop_scope = js_mkscope(js);
10084
+
}
10085
+
}
10086
+
10087
+
static inline jsval_t loop_block_exec(struct js *js, loop_block_ctx_t *ctx) {
10088
+
if (ctx->needs_scope) scope_clear_props(js, ctx->loop_scope);
10089
+
return js_block_or_stmt(js);
10090
+
}
10091
+
10092
+
static inline void loop_block_cleanup(struct js *js, loop_block_ctx_t *ctx) {
10093
+
if (ctx->needs_scope) delscope(js);
10094
+
}
10095
+
10021
10096
static jsval_t js_if(struct js *js) {
10022
10097
js->consumed = 1;
10023
10098
EXPECT(TOK_LPAREN, );
···
10611
10686
static jsval_t js_while(struct js *js) {
10612
10687
uint8_t flags = js->flags, exe = !(flags & F_NOEXEC);
10613
10688
jsval_t res = js_mkundef(), v;
10689
+
loop_block_ctx_t loop_ctx = {0};
10614
10690
10615
10691
bool use_label_stack = label_stack && utarray_len(label_stack) > 0;
10616
10692
int marker_index = 0;
···
10631
10707
if (!expect(js, TOK_RPAREN, &res)) goto done;
10632
10708
10633
10709
jsoff_t body_start = js->pos;
10710
+
if (exe) loop_block_init(js, &loop_ctx);
10711
+
10634
10712
v = js_block_or_stmt(js);
10635
10713
if (is_err(v)) { res = v; goto done; }
10636
10714
jsoff_t body_end = js->pos;
···
10653
10731
js->consumed = 1;
10654
10732
js->flags = (flags & ~F_NOEXEC) | F_LOOP;
10655
10733
10656
-
v = js_block_or_stmt(js);
10734
+
v = loop_block_exec(js, &loop_ctx);
10657
10735
if (is_err(v)) {
10658
-
res = v;
10659
-
break;
10736
+
res = v; break;
10660
10737
}
10661
10738
10662
10739
if (label_flags & F_CONTINUE_LABEL) {
···
10676
10753
break;
10677
10754
}
10678
10755
}
10756
+
loop_block_cleanup(js, &loop_ctx);
10679
10757
}
10680
10758
10681
10759
js->pos = body_end;
···
10705
10783
static jsval_t js_do_while(struct js *js) {
10706
10784
uint8_t flags = js->flags, exe = !(flags & F_NOEXEC);
10707
10785
jsval_t res = js_mkundef(), v;
10786
+
loop_block_ctx_t loop_ctx = {0};
10708
10787
10709
10788
bool use_label_stack = label_stack && utarray_len(label_stack) > 0;
10710
10789
int marker_index = 0;
···
10718
10797
10719
10798
jsoff_t body_start = js->pos;
10720
10799
bool is_block = (next(js) == TOK_LBRACE);
10800
+
if (exe) loop_block_init(js, &loop_ctx);
10801
+
10721
10802
js->flags |= F_NOEXEC;
10722
10803
v = js_block_or_stmt(js);
10723
10804
if (is_err(v)) { res = v; goto done; }
···
10743
10824
js->consumed = 1;
10744
10825
js->flags = (flags & ~F_NOEXEC) | F_LOOP;
10745
10826
10746
-
v = js_block_or_stmt(js);
10827
+
v = loop_block_exec(js, &loop_ctx);
10747
10828
if (is_err(v)) {
10748
-
res = v;
10749
-
break;
10829
+
res = v; break;
10750
10830
}
10751
10831
10752
10832
if (label_flags & F_CONTINUE_LABEL) {
···
10775
10855
break;
10776
10856
}
10777
10857
} while (js_truthy(js, v));
10858
+
loop_block_cleanup(js, &loop_ctx);
10778
10859
}
10779
10860
10780
10861
js->pos = cond_end;