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Don't brace let declaration if single statement controlled by if/do/while/for/with (351070, r=mrbkap).

This commit is contained in:
brendan%mozilla.org 2006-09-11 19:45:24 +00:00
Родитель 90a0cbc45c
Коммит 4f62c4c886
4 изменённых файлов: 108 добавлений и 15 удалений
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2
js/src/jsemit.c
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@ -3498,12 +3498,12 @@ EmitVariables(JSContext *cx, JSCodeGenerator *cg, JSParseNode *pn,
JSBool let, forInVar;
#if JS_HAS_BLOCK_SCOPE
JSBool forInLet, popScope;
JSStmtInfo *stmt, *scopeStmt;
#endif
ptrdiff_t off, noteIndex, tmp;
JSParseNode *pn2, *pn3;
JSOp op;
jsatomid atomIndex;
JSStmtInfo *stmt, *scopeStmt;
uintN oldflags;
/* Default in case of JS_HAS_BLOCK_SCOPE early return, below. */

2
js/src/jsemit.h
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@ -526,6 +526,8 @@ typedef enum JSSrcNoteType {
* to be adjusted, but these "offsets" are too small to span a span-dependent
* instruction, so can be used to denote distinct declaration syntaxes to the
* decompiler.
*
* NB: the var_prefix array in jsopcode.c depends on these dense indexes.
*/
#define SRC_DECL_VAR 0
#define SRC_DECL_CONST 1

117
js/src/jsopcode.c
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@ -556,6 +556,14 @@ js_QuoteString(JSContext *cx, JSString *str, jschar quote)
/************************************************************************/
#if JS_HAS_BLOCK_SCOPE
typedef enum JSBraceState {
ALWAYS_BRACE,
MAYBE_BRACE,
DONT_BRACE
} JSBraceState;
#endif
struct JSPrinter {
Sprinter sprinter; /* base class state */
JSArenaPool pool; /* string allocation pool */
@ -564,6 +572,10 @@ struct JSPrinter {
JSPackedBool grouped; /* in parenthesized expression context */
JSScript *script; /* script being printed */
JSScope *scope; /* script function scope */
#if JS_HAS_BLOCK_SCOPE
JSBraceState braceState; /* remove braces around let declaration */
ptrdiff_t spaceOffset; /* -1 or offset of space before maybe-{ */
#endif
};
/*
@ -589,6 +601,10 @@ js_NewPrinter(JSContext *cx, const char *name, uintN indent, JSBool pretty)
jp->grouped = (indent & JS_IN_GROUP_CONTEXT) != 0;
jp->script = NULL;
jp->scope = NULL;
#if JS_HAS_BLOCK_SCOPE
jp->braceState = ALWAYS_BRACE;
jp->spaceOffset = -1;
#endif
return jp;
}
@ -616,6 +632,31 @@ js_GetPrinterOutput(JSPrinter *jp)
return str;
}
#if !JS_HAS_BLOCK_SCOPE
# define SET_MAYBE_BRACE(jp) jp
#else
# define SET_MAYBE_BRACE(jp) ((jp)->braceState = MAYBE_BRACE, (jp))
static void
SetDontBrace(JSPrinter *jp)
{
ptrdiff_t offset;
/* When not pretty-printing, newline after brace is chopped. */
JS_ASSERT(jp->spaceOffset < 0);
offset = jp->sprinter.offset - (jp->pretty ? 3 : 2);
/* The shortest case is "if (x) {". */
JS_ASSERT(offset >= 6);
JS_ASSERT(jp->sprinter.base[offset+0] == ' ');
JS_ASSERT(jp->sprinter.base[offset+1] == '{');
JS_ASSERT(!jp->pretty || jp->sprinter.base[offset+2] == '\n');
jp->spaceOffset = offset;
jp->braceState = DONT_BRACE;
}
#endif
int
js_printf(JSPrinter *jp, const char *format, ...)
{
@ -630,9 +671,40 @@ js_printf(JSPrinter *jp, const char *format, ...)
/* If pretty-printing, expand magic tab into a run of jp->indent spaces. */
if (*format == '\t') {
format++;
#if JS_HAS_BLOCK_SCOPE
if (*format == '}' && jp->braceState != ALWAYS_BRACE) {
JSBraceState braceState;
braceState = jp->braceState;
jp->braceState = ALWAYS_BRACE;
if (braceState == DONT_BRACE) {
ptrdiff_t offset, from;
JS_ASSERT(format[1] == '\n' || format[1] == ' ');
offset = jp->spaceOffset;
JS_ASSERT(offset >= 6);
/* Replace " {\n" at the end of jp->sprinter with "\n". */
bp = jp->sprinter.base;
JS_ASSERT(bp[offset+0] == ' ');
JS_ASSERT(bp[offset+1] == '{');
JS_ASSERT(!jp->pretty || bp[offset+2] == '\n');
from = offset + 2;
memmove(bp + offset, bp + from, jp->sprinter.offset - from);
jp->sprinter.offset -= 2;
jp->spaceOffset = -1;
format += 2;
if (*format == '\0')
return 0;
}
}
#endif
if (jp->pretty && Sprint(&jp->sprinter, "%*s", jp->indent, "") < 0)
return -1;
format++;
}
/* Suppress newlines (must be once per format, at the end) if not pretty. */
@ -921,17 +993,18 @@ GetSlotAtom(JSPrinter *jp, JSPropertyOp getter, uintN slot)
return NULL;
}
/*
* NB: Indexed by SRC_DECL_* defines from jsemit.h.
*/
static const char * const var_prefix[] = {"var ", "const ", "let "};
static const char *
VarPrefix(jssrcnote *sn)
{
if (sn && SN_TYPE(sn) == SRC_DECL) {
ptrdiff_t type = js_GetSrcNoteOffset(sn, 0);
if (type == SRC_DECL_VAR)
return "var ";
if (type == SRC_DECL_CONST)
return "const ";
if (type == SRC_DECL_LET)
return "let ";
if ((uintN)type <= SRC_DECL_LET)
return var_prefix[type];
}
return "";
}
@ -1127,7 +1200,7 @@ Decompile(SprintStack *ss, jsbytecode *pc, intN nb)
todo = -2;
switch (sn ? SN_TYPE(sn) : SRC_NULL) {
case SRC_WHILE:
js_printf(jp, "\tdo {\n");
js_printf(SET_MAYBE_BRACE(jp), "\tdo {\n");
jp->indent += 4;
break;
@ -1163,7 +1236,7 @@ Decompile(SprintStack *ss, jsbytecode *pc, intN nb)
}
/* Do the loop body. */
js_printf(jp, ") {\n");
js_printf(SET_MAYBE_BRACE(jp), ") {\n");
jp->indent += 4;
oplen = (cond) ? js_CodeSpec[pc[cond]].length : 0;
DECOMPILE_CODE(pc + cond + oplen, next - cond - oplen);
@ -1433,6 +1506,20 @@ Decompile(SprintStack *ss, jsbytecode *pc, intN nb)
default:
rval = POP_STR();
if (*rval != '\0') {
#if JS_HAS_BLOCK_SCOPE
/*
* If a let declaration is the only child of a control
* structure that does not require braces, it must not
* be braced. If it were braced explicitly, it would
* be bracketed by JSOP_ENTERBLOCK/JSOP_LEAVEBLOCK.
*/
if (jp->braceState == MAYBE_BRACE &&
pc + JSOP_POP_LENGTH == endpc &&
!strncmp(rval, var_prefix[SRC_DECL_LET], 4) &&
rval[4] != '(') {
SetDontBrace(jp);
}
#endif
js_printf(jp,
(*rval == '{') ? "\t(%s);\n" : "\t%s;\n",
rval);
@ -1463,7 +1550,7 @@ Decompile(SprintStack *ss, jsbytecode *pc, intN nb)
case JSOP_ENTERWITH:
JS_ASSERT(!js_GetSrcNote(jp->script, pc));
rval = POP_STR();
js_printf(jp, "\twith (%s) {\n", rval);
js_printf(SET_MAYBE_BRACE(jp), "\twith (%s) {\n", rval);
jp->indent += 4;
todo = Sprint(&ss->sprinter, with_cookie);
break;
@ -1799,7 +1886,7 @@ Decompile(SprintStack *ss, jsbytecode *pc, intN nb)
if (Sprint(&ss->sprinter, " if (%s)", rval) < 0)
return JS_FALSE;
} else {
js_printf(jp, "\tif (%s) {\n", rval);
js_printf(SET_MAYBE_BRACE(jp), "\tif (%s) {\n", rval);
jp->indent += 4;
}
@ -1814,7 +1901,8 @@ Decompile(SprintStack *ss, jsbytecode *pc, intN nb)
LOCAL_ASSERT(*pc == JSOP_GOTO || *pc == JSOP_GOTOX);
oplen = js_CodeSpec[*pc].length;
len = GetJumpOffset(pc, pc);
js_printf(jp, "\t} else {\n");
js_printf(jp, "\t} else");
js_printf(SET_MAYBE_BRACE(jp), " {\n");
jp->indent += 4;
DECOMPILE_CODE(pc + oplen, len - oplen);
}
@ -1828,7 +1916,7 @@ Decompile(SprintStack *ss, jsbytecode *pc, intN nb)
case SRC_WHILE:
rval = POP_STR();
js_printf(jp, "\twhile (%s) {\n", rval);
js_printf(SET_MAYBE_BRACE(jp), "\twhile (%s) {\n", rval);
jp->indent += 4;
tail = js_GetSrcNoteOffset(sn, 0);
DECOMPILE_CODE(pc + oplen, tail - oplen);
@ -2011,7 +2099,8 @@ Decompile(SprintStack *ss, jsbytecode *pc, intN nb)
ss->sprinter.offset += PAREN_SLOP;
DECOMPILE_CODE(pc + oplen, tail - oplen);
} else {
js_printf(jp, "\t%s in %s) {\n", lval, rval);
js_printf(SET_MAYBE_BRACE(jp), "\t%s in %s) {\n",
lval, rval);
jp->indent += 4;
DECOMPILE_CODE(pc + oplen, tail - oplen);
jp->indent -= 4;

2
js/src/jsparse.c
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@ -2339,6 +2339,7 @@ ReturnOrYield(JSContext *cx, JSTokenStream *ts, JSTreeContext *tc,
return pn;
}
#if JS_HAS_BLOCK_SCOPE
static JSStmtInfo *
FindMaybeScopeStatement(JSTreeContext *tc)
{
@ -2352,6 +2353,7 @@ FindMaybeScopeStatement(JSTreeContext *tc)
}
return NULL;
}
#endif
static JSParseNode *
PushLexicalScope(JSContext *cx, JSTokenStream *ts, JSTreeContext *tc,