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[PATCH 4/8] parse.error: document and diagnose the incompatibility with
From: |
Akim Demaille |
Subject: |
[PATCH 4/8] parse.error: document and diagnose the incompatibility with %token-table |
Date: |
Mon, 10 Feb 2020 20:49:12 +0100 |
* doc/bison.texi (Tokens from Literals): Move to code using
%token-table to...
(Decl Summary: %token-table): here.
* data/skeletons/bison.m4: Implement mutual exclusion.
* tests/input.at: Check it.
* doc/local.mk: Be robust to the removal of doc/.
---
data/skeletons/bison.m4 | 8 +++++++
doc/bison.texi | 48 +++++++++++++++++++++--------------------
doc/local.mk | 7 +++---
tests/input.at | 28 ++++++++++++++++++++++++
4 files changed, 65 insertions(+), 26 deletions(-)
diff --git a/data/skeletons/bison.m4 b/data/skeletons/bison.m4
index 37a64f1c..ae4154c9 100644
--- a/data/skeletons/bison.m4
+++ b/data/skeletons/bison.m4
@@ -1118,3 +1118,11 @@ b4_percent_define_ifdef([api.value.type],
# api.value.union.name.
b4_percent_define_check_kind([api.value.union.name], [keyword])
+
+# parse.error (custom|detailed) >< token-table.
+b4_token_table_if(
+[b4_parse_error_bmatch([custom\|detailed],
+[b4_complain_at(b4_percent_define_get_loc([parse.error]),
+ [['%s' and '%s' cannot be used together]],
+ [%token-table],
+ [%define parse.error (custom|detailed)])])])
diff --git a/doc/bison.texi b/doc/bison.texi
index 37853834..678101a3 100644
--- a/doc/bison.texi
+++ b/doc/bison.texi
@@ -5780,6 +5780,8 @@ This is similar to how most shells resolve commands.
@end deffn
@deffn {Directive} %token-table
+This feature is obsolescent, avoid it in new projects.
+
Generate an array of token names in the parser implementation file. The
name of the array is @code{yytname}; @code{yytname[@var{i}]} is the name of
the token whose internal Bison token code number is @var{i}. The first
@@ -5809,6 +5811,29 @@ The number of grammar rules,
@item YYNSTATES
The number of parser states (@pxref{Parser States}).
@end table
+
+Here's code for looking up a multicharacter token in @code{yytname},
+assuming that the characters of the token are stored in @code{token_buffer},
+and assuming that the token does not contain any characters like @samp{"}
+that require escaping.
+
+@example
+for (int i = 0; i < YYNTOKENS; i++)
+ if (yytname[i]
+ && yytname[i][0] == '"'
+ && ! strncmp (yytname[i] + 1, token_buffer,
+ strlen (token_buffer))
+ && yytname[i][strlen (token_buffer) + 1] == '"'
+ && yytname[i][strlen (token_buffer) + 2] == 0)
+ break;
+@end example
+
+This method is discouraged: the primary purpose of string aliases is forging
+good error messages, not describing the spelling of keywords. In addition,
+looking for the token type at runtime incurs a (small but noticeable) cost.
+
+Finally, @code{%token-table} is incompatible with the @code{custom} and
+@code{detailed} values of the @code{parse.error} @code{%define} variable.
@end deffn
@deffn {Directive} %verbose
@@ -7089,29 +7114,6 @@ forging good error messages, not describing the spelling
of keywords. In
addition, looking for the token type at runtime incurs a (small but
noticeable) cost.
-The index of the token in the table is the token type's code. The name of a
-multicharacter token is recorded in @code{yytname} with a double-quote, the
-token's characters, and another double-quote. The token's characters are
-escaped as necessary to be suitable as input to Bison.
-
-Here's code for looking up a multicharacter token in @code{yytname},
-assuming that the characters of the token are stored in @code{token_buffer},
-and assuming that the token does not contain any characters like @samp{"}
-that require escaping.
-
-@example
-for (int i = 0; i < YYNTOKENS; i++)
- @{
- if (yytname[i]
- && yytname[i][0] == '"'
- && ! strncmp (yytname[i] + 1, token_buffer,
- strlen (token_buffer))
- && yytname[i][strlen (token_buffer) + 1] == '"'
- && yytname[i][strlen (token_buffer) + 2] == 0)
- break;
- @}
-@end example
-
The @code{yytname} table is generated only if you use the
@code{%token-table} declaration. @xref{Decl Summary}.
@end itemize
diff --git a/doc/local.mk b/doc/local.mk
index d8c235ed..9695b358 100644
--- a/doc/local.mk
+++ b/doc/local.mk
@@ -110,14 +110,15 @@ EXTRA_DIST += $(top_srcdir)/doc/bison.help
if ! CROSS_COMPILING
MAINTAINERCLEANFILES += $(top_srcdir)/doc/bison.help
$(top_srcdir)/doc/bison.help: src/bison$(EXEEXT)
- $(AM_V_GEN)LC_ALL=C tests/bison --version >doc/bison.help.tmp
+ $(AM_V_GEN)$(MKDIR_P) %D%
+ $(AM_V_at) LC_ALL=C tests/bison --version >%D%/bison.help.tmp
$(AM_V_at) LC_ALL=C tests/bison --help | \
## Avoid depending on the path to Bison.
sed -e 's,^Usage: .*/bison \[OPTION\],Usage: bison [OPTION],g' \
## Avoid variations in the output depending on whether we are
## on a glibc system.
- -e '/translation bugs/d' >>doc/bison.help.tmp
- $(AM_V_at)$(top_srcdir)/build-aux/move-if-change doc/bison.help.tmp $@
+ -e '/translation bugs/d' >>%D%/bison.help.tmp
+ $(AM_V_at)$(top_srcdir)/build-aux/move-if-change %D%/bison.help.tmp $@
endif ! CROSS_COMPILING
diff --git a/tests/input.at b/tests/input.at
index 5b37d715..29c74e4d 100644
--- a/tests/input.at
+++ b/tests/input.at
@@ -2888,3 +2888,31 @@ input.y:9.1-21: definition of api.token.raw
AT_BISON_OPTION_POPDEFS
AT_CLEANUP
+
+
+
+## ------------------------------ ##
+## %token-table and parse.error. ##
+## ------------------------------ ##
+
+AT_SETUP([[%token-table and parse.error]])
+
+# AT_TEST(DIRECTIVES, ERROR-LOCATION)
+# -----------------------------------
+m4_pushdef([AT_TEST],
+[AT_DATA([[input.y]],
+[[$1
+%%
+exp: %empty;
+]])
+AT_BISON_CHECK([[input.y]], [[1]], [[]],
+[$2: error: '%token-table' and '%define parse.error (custom|detailed)' cannot
be used together
+])
+])
+
+AT_TEST([%define parse.error custom %token-table], [[input.y:1.1-26]])
+AT_TEST([%define parse.error detailed %token-table],[[input.y:1.1-28]])
+
+m4_popdef([AT_TEST])
+
+AT_CLEANUP
--
2.25.0
- [PATCH 0/8] Various updates, Akim Demaille, 2020/02/10
- [PATCH 1/8] doc: work around problems with PDF generation, Akim Demaille, 2020/02/10
- [PATCH 2/8] doc: formatting changes, Akim Demaille, 2020/02/10
- [PATCH 4/8] parse.error: document and diagnose the incompatibility with %token-table,
Akim Demaille <=
- [PATCH 3/8] doc: spell check, Akim Demaille, 2020/02/10
- [PATCH 6/8] gnulib: update, Akim Demaille, 2020/02/10
- [PATCH 7/8] regen, Akim Demaille, 2020/02/10
- [PATCH 5/8] build: prefer %D% and %C% to hard coded values, Akim Demaille, 2020/02/10
- [PATCH 8/8] build: pacify syntax-check, Akim Demaille, 2020/02/10