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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)
/* Error token number */
/* Error symbol internal number. */
#define YYTERROR 1
/* Error token external number. */
#define YYERRCODE 256
]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 *yyesp = yyes_prev;
/* Reduce until we encounter a shift and thereby accept the token. */
YYDPRINTF ((stderr, "LAC: checking lookahead %s:", yysymbol_name(yytoken)));
if (yytoken == YYUNDEFTOK)
{
@@ -959,6 +961,7 @@ yy_lac (yy_state_t *yyesa, yy_state_t **yyes,
|| (yyrule += yytoken) < 0 || YYLAST < yyrule
|| yycheck[yyrule] != yytoken)
{
/* Use the default action. */
yyrule = yydefact[+*yyesp];
if (yyrule == 0)
{
@@ -968,6 +971,7 @@ yy_lac (yy_state_t *yyesa, yy_state_t **yyes,
}
else
{
/* Use the action from yytable. */
yyrule = yytable[yyrule];
if (yytable_value_is_error (yyrule))
{
@@ -981,9 +985,12 @@ yy_lac (yy_state_t *yyesa, yy_state_t **yyes,
}
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];
YYDPRINTF ((stderr, " R%d", yyrule - 1));
/* First pop from the LAC stack as many tokens as possible. */
if (yyesp != yyes_prev)
{
YYPTRDIFF_T yysize = yyesp - *yyes + 1;
@@ -994,13 +1001,15 @@ yy_lac (yy_state_t *yyesa, yy_state_t **yyes,
}
else
{
yylen -= yysize;
yyesp = yyes_prev;
yylen -= yysize;
}
}
/* Only afterwards look at the main stack. */
if (yylen)
yyesp = yyes_prev -= yylen;
}
/* Push the resulting state of the reduction. */
{
yy_state_fast_t yystate;
{
@@ -1414,8 +1423,10 @@ b4_function_define([[yyparse]], [[int]], b4_parse_param)[
])],
[b4_declare_parser_state_variables
])b4_lac_if([[
/* Whether LAC context is established. A Boolean. */
int yy_lac_established = 0;]])[
int yyn;
/* The return value of yyparse. */
int yyresult;
/* Lookahead token as an internal (translated) token number. */
int yytoken = 0;