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yacc.c: comment changes

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In particular, import Adrian Vogelsgesang's comments about LAC from
lalr1.cc.

* data/skeletons/yacc.c: here.
This commit is contained in:
Akim Demaille
2020-01-11 17:38:57 +01:00
parent 32b529f038
commit 1c0adb410d
1 changed files with 14 additions and 3 deletions
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17
data/skeletons/yacc.c
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@@ -671,8 +671,9 @@ static const ]b4_int_type_for([b4_toknum])[ yytoknum[] =
} \ } \
while (0) while (0)
/* Error token number */ /* Error symbol internal number. */
#define YYTERROR 1 #define YYTERROR 1
/* Error token external number. */
#define YYERRCODE 256 #define YYERRCODE 256
]b4_locations_if([[ ]b4_locations_if([[
@@ -946,6 +947,7 @@ yy_lac (yy_state_t *yyesa, yy_state_t **yyes,
{ {
yy_state_t *yyes_prev = yyssp; yy_state_t *yyes_prev = yyssp;
yy_state_t *yyesp = yyes_prev; yy_state_t *yyesp = yyes_prev;
/* Reduce until we encounter a shift and thereby accept the token. */
YYDPRINTF ((stderr, "LAC: checking lookahead %s:", yysymbol_name(yytoken))); YYDPRINTF ((stderr, "LAC: checking lookahead %s:", yysymbol_name(yytoken)));
if (yytoken == YYUNDEFTOK) if (yytoken == YYUNDEFTOK)
{ {
@@ -959,6 +961,7 @@ yy_lac (yy_state_t *yyesa, yy_state_t **yyes,
|| (yyrule += yytoken) < 0 || YYLAST < yyrule || (yyrule += yytoken) < 0 || YYLAST < yyrule
|| yycheck[yyrule] != yytoken) || yycheck[yyrule] != yytoken)
{ {
/* Use the default action. */
yyrule = yydefact[+*yyesp]; yyrule = yydefact[+*yyesp];
if (yyrule == 0) if (yyrule == 0)
{ {
@@ -968,6 +971,7 @@ yy_lac (yy_state_t *yyesa, yy_state_t **yyes,
} }
else else
{ {
/* Use the action from yytable. */
yyrule = yytable[yyrule]; yyrule = yytable[yyrule];
if (yytable_value_is_error (yyrule)) if (yytable_value_is_error (yyrule))
{ {
@@ -981,9 +985,12 @@ yy_lac (yy_state_t *yyesa, yy_state_t **yyes,
} }
yyrule = -yyrule; yyrule = -yyrule;
} }
/* By now we know we have to simulate a reduce. */
YYDPRINTF ((stderr, " R%d", yyrule - 1));
{ {
/* Pop the corresponding number of values from the stack. */
YYPTRDIFF_T yylen = yyr2[yyrule]; YYPTRDIFF_T yylen = yyr2[yyrule];
YYDPRINTF ((stderr, " R%d", yyrule - 1)); /* First pop from the LAC stack as many tokens as possible. */
if (yyesp != yyes_prev) if (yyesp != yyes_prev)
{ {
YYPTRDIFF_T yysize = yyesp - *yyes + 1; YYPTRDIFF_T yysize = yyesp - *yyes + 1;
@@ -994,13 +1001,15 @@ yy_lac (yy_state_t *yyesa, yy_state_t **yyes,
} }
else else
{ {
yylen -= yysize;
yyesp = yyes_prev; yyesp = yyes_prev;
yylen -= yysize;
} }
} }
/* Only afterwards look at the main stack. */
if (yylen) if (yylen)
yyesp = yyes_prev -= yylen; yyesp = yyes_prev -= yylen;
} }
/* Push the resulting state of the reduction. */
{ {
yy_state_fast_t yystate; yy_state_fast_t yystate;
{ {
@@ -1414,8 +1423,10 @@ b4_function_define([[yyparse]], [[int]], b4_parse_param)[
])], ])],
[b4_declare_parser_state_variables [b4_declare_parser_state_variables
])b4_lac_if([[ ])b4_lac_if([[
/* Whether LAC context is established. A Boolean. */
int yy_lac_established = 0;]])[ int yy_lac_established = 0;]])[
int yyn; int yyn;
/* The return value of yyparse. */
int yyresult; int yyresult;
/* Lookahead token as an internal (translated) token number. */ /* Lookahead token as an internal (translated) token number. */
int yytoken = 0; int yytoken = 0;