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The location tracking mechanism is precious for parse error

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messages.  Nevertheless, it is enabled only when `@n' is used in
the grammar, which is a different issue (you can use it in error
message, but not in the grammar per se).  Therefore, there should
be another means to enable it.
* src/getargs.c (getargs): Support `--locations'.
(usage): Report it.
* src/getargs.h (locationsflag): Export it.
* src/lex.c (percent_table): Support `%locations'.
* src/reader.c (yylsp_needed): Remove this variable, now replaced
with `locationsflag'.
* doc/bison.texinfo: Document `--locations' and `%locations'.
Sort the options.
* tests/calc.m4: Test it.
For regularity of the names, replace each
(nolineflag, toknumflag, rawtokenumflag, noparserflag): with...
(no_lineflag, token_tableflag, rawflag, no_parserflag): this.
In addition replace each `flag' with `_flag'.
This commit is contained in:
Akim Demaille
2000-10-02 10:20:59 +00:00
parent d6c2cba06d
commit 89cab50df1
13 changed files with 377 additions and 251 deletions
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210
doc/bison.texinfo
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@@ -3180,14 +3180,23 @@ Declare the type of semantic values for a nonterminal symbol
(@pxref{Type Decl, ,Nonterminal Symbols}).
@item %start
Specify the grammar's start symbol (@pxref{Start Decl, ,The Start-Symbol}).
Specify the grammar's start symbol (@pxref{Start Decl, ,The
Start-Symbol}).
@item %expect
Declare the expected number of shift-reduce conflicts
(@pxref{Expect Decl, ,Suppressing Conflict Warnings}).
@item %locations
Generate the code processing the locations (@pxref{Action Features,
,Special Features for Use in Actions}). This mode is enabled as soon as
the grammar uses the special @samp{@@@var{n}} tokens, but if your
grammar does not use it, using @samp{%locations} allows for more
accurate parse error messages.
@item %pure_parser
Request a pure (reentrant) parser program (@pxref{Pure Decl, ,A Pure (Reentrant) Parser}).
Request a pure (reentrant) parser program (@pxref{Pure Decl, ,A Pure
(Reentrant) Parser}).
@item %no_lines
Don't generate any @code{#line} preprocessor commands in the parser
@@ -3474,16 +3483,17 @@ then the code in @code{yylex} might look like this:
@subsection Textual Positions of Tokens
@vindex yylloc
If you are using the @samp{@@@var{n}}-feature (@pxref{Action Features, ,Special Features for Use in Actions}) in
actions to keep track of the textual locations of tokens and groupings,
then you must provide this information in @code{yylex}. The function
@code{yyparse} expects to find the textual location of a token just parsed
in the global variable @code{yylloc}. So @code{yylex} must store the
proper data in that variable. The value of @code{yylloc} is a structure
and you need only initialize the members that are going to be used by the
actions. The four members are called @code{first_line},
@code{first_column}, @code{last_line} and @code{last_column}. Note that
the use of this feature makes the parser noticeably slower.
If you are using the @samp{@@@var{n}}-feature (@pxref{Action Features,
,Special Features for Use in Actions}) in actions to keep track of the
textual locations of tokens and groupings, then you must provide this
information in @code{yylex}. The function @code{yyparse} expects to
find the textual location of a token just parsed in the global variable
@code{yylloc}. So @code{yylex} must store the proper data in that
variable. The value of @code{yylloc} is a structure and you need only
initialize the members that are going to be used by the actions. The
four members are called @code{first_line}, @code{first_column},
@code{last_line} and @code{last_column}. Note that the use of this
feature makes the parser noticeably slower.
@tindex YYLTYPE
The data type of @code{yylloc} has the name @code{YYLTYPE}.
@@ -4894,25 +4904,56 @@ Here is a list of options that can be used with Bison, alphabetized by
short option. It is followed by a cross key alphabetized by long
option.
@table @samp
@item -b @var{file-prefix}
@itemx --file-prefix=@var{prefix}
Specify a prefix to use for all Bison output file names. The names are
chosen as if the input file were named @file{@var{prefix}.c}.
@c Please, keep this ordered as in `bison --help'.
@noindent
Operations modes:
@table @option
@item -h
@itemx --help
Print a summary of the command-line options to Bison and exit.
@item -d
@itemx --defines
Write an extra output file containing macro definitions for the token
type names defined in the grammar and the semantic value type
@code{YYSTYPE}, as well as a few @code{extern} variable declarations.
@item -V
@itemx --version
Print the version number of Bison and exit.
If the parser output file is named @file{@var{name}.c} then this file
is named @file{@var{name}.h}.@refill
@need 1750
@item -y
@itemx --yacc
@itemx --fixed-output-files
Equivalent to @samp{-o y.tab.c}; the parser output file is called
@file{y.tab.c}, and the other outputs are called @file{y.output} and
@file{y.tab.h}. The purpose of this option is to imitate Yacc's output
file name conventions. Thus, the following shell script can substitute
for Yacc:@refill
This output file is essential if you wish to put the definition of
@code{yylex} in a separate source file, because @code{yylex} needs to
be able to refer to token type codes and the variable
@code{yylval}. @xref{Token Values, ,Semantic Values of Tokens}.@refill
@example
bison -y $*
@end example
@end table
@noindent
Tuning the parser:
@table @option
@item -t
@itemx --debug
Output a definition of the macro @code{YYDEBUG} into the parser file,
so that the debugging facilities are compiled. @xref{Debugging, ,Debugging Your Parser}.
@item --locations
Pretend that @code{%locactions} was specified. @xref{Decl Summary}.
@item -p @var{prefix}
@itemx --name-prefix=@var{prefix}
Rename the external symbols used in the parser so that they start with
@var{prefix} instead of @samp{yy}. The precise list of symbols renamed
is @code{yyparse}, @code{yylex}, @code{yyerror}, @code{yynerrs},
@code{yylval}, @code{yychar} and @code{yydebug}.
For example, if you use @samp{-p c}, the names become @code{cparse},
@code{clex}, and so on.
@xref{Multiple Parsers, ,Multiple Parsers in the Same Program}.
@item -l
@itemx --no-lines
@@ -4932,33 +4973,37 @@ This option also tells Bison to write the C code for the grammar actions
into a file named @file{@var{filename}.act}, in the form of a
brace-surrounded body fit for a @code{switch} statement.
@item -o @var{outfile}
@itemx --output-file=@var{outfile}
Specify the name @var{outfile} for the parser file.
The other output files' names are constructed from @var{outfile}
as described under the @samp{-v} and @samp{-d} options.
@item -p @var{prefix}
@itemx --name-prefix=@var{prefix}
Rename the external symbols used in the parser so that they start with
@var{prefix} instead of @samp{yy}. The precise list of symbols renamed
is @code{yyparse}, @code{yylex}, @code{yyerror}, @code{yynerrs},
@code{yylval}, @code{yychar} and @code{yydebug}.
For example, if you use @samp{-p c}, the names become @code{cparse},
@code{clex}, and so on.
@xref{Multiple Parsers, ,Multiple Parsers in the Same Program}.
@item -r
@itemx --raw
Pretend that @code{%raw} was specified. @xref{Decl Summary}.
@item -t
@itemx --debug
Output a definition of the macro @code{YYDEBUG} into the parser file,
so that the debugging facilities are compiled. @xref{Debugging, ,Debugging Your Parser}.
@item -k
@itemx --token-table
Pretend that @code{%token_table} was specified. @xref{Decl Summary}.
@end table
@noindent
Adjust the output:
@table @option
@item -d
@itemx --defines
Write an extra output file containing macro definitions for the token
type names defined in the grammar and the semantic value type
@code{YYSTYPE}, as well as a few @code{extern} variable declarations.
If the parser output file is named @file{@var{name}.c} then this file
is named @file{@var{name}.h}.@refill
This output file is essential if you wish to put the definition of
@code{yylex} in a separate source file, because @code{yylex} needs to
be able to refer to token type codes and the variable
@code{yylval}. @xref{Token Values, ,Semantic Values of Tokens}.@refill
@item -b @var{file-prefix}
@itemx --file-prefix=@var{prefix}
Specify a prefix to use for all Bison output file names. The names are
chosen as if the input file were named @file{@var{prefix}.c}.
@item -v
@itemx --verbose
@@ -4976,27 +5021,12 @@ Therefore, if the input file is @file{foo.y}, then the parser file is
called @file{foo.tab.c} by default. As a consequence, the verbose
output file is called @file{foo.output}.@refill
@item -V
@itemx --version
Print the version number of Bison and exit.
@item -o @var{outfile}
@itemx --output-file=@var{outfile}
Specify the name @var{outfile} for the parser file.
@item -h
@itemx --help
Print a summary of the command-line options to Bison and exit.
@need 1750
@item -y
@itemx --yacc
@itemx --fixed-output-files
Equivalent to @samp{-o y.tab.c}; the parser output file is called
@file{y.tab.c}, and the other outputs are called @file{y.output} and
@file{y.tab.h}. The purpose of this option is to imitate Yacc's output
file name conventions. Thus, the following shell script can substitute
for Yacc:@refill
@example
bison -y $*
@end example
The other output files' names are constructed from @var{outfile}
as described under the @samp{-v} and @samp{-d} options.
@end table
@node Environment Variables, Option Cross Key, Bison Options, Invocation
@@ -5280,15 +5310,17 @@ Bison declarations section or the additional C code section.
@xref{Grammar Layout, ,The Overall Layout of a Bison Grammar}.
@item %@{ %@}
All code listed between @samp{%@{} and @samp{%@}} is copied directly
to the output file uninterpreted. Such code forms the ``C
declarations'' section of the input file. @xref{Grammar Outline, ,Outline of a Bison Grammar}.
All code listed between @samp{%@{} and @samp{%@}} is copied directly to
the output file uninterpreted. Such code forms the ``C declarations''
section of the input file. @xref{Grammar Outline, ,Outline of a Bison
Grammar}.
@item /*@dots{}*/
Comment delimiters, as in C.
@item :
Separates a rule's result from its components. @xref{Rules, ,Syntax of Grammar Rules}.
Separates a rule's result from its components. @xref{Rules, ,Syntax of
Grammar Rules}.
@item ;
Terminates a rule. @xref{Rules, ,Syntax of Grammar Rules}.
@@ -5305,13 +5337,15 @@ Separates alternate rules for the same result nonterminal.
@table @asis
@item Backus-Naur Form (BNF)
Formal method of specifying context-free grammars. BNF was first used
in the @cite{ALGOL-60} report, 1963. @xref{Language and Grammar, ,Languages and Context-Free Grammars}.
in the @cite{ALGOL-60} report, 1963. @xref{Language and Grammar,
,Languages and Context-Free Grammars}.
@item Context-free grammars
Grammars specified as rules that can be applied regardless of context.
Thus, if there is a rule which says that an integer can be used as an
expression, integers are allowed @emph{anywhere} an expression is
permitted. @xref{Language and Grammar, ,Languages and Context-Free Grammars}.
permitted. @xref{Language and Grammar, ,Languages and Context-Free
Grammars}.
@item Dynamic allocation
Allocation of memory that occurs during execution, rather than at
@@ -5352,8 +5386,9 @@ Operators having left associativity are analyzed from left to right:
@samp{c}. @xref{Precedence, ,Operator Precedence}.
@item Left recursion
A rule whose result symbol is also its first component symbol;
for example, @samp{expseq1 : expseq1 ',' exp;}. @xref{Recursion, ,Recursive Rules}.
A rule whose result symbol is also its first component symbol; for
example, @samp{expseq1 : expseq1 ',' exp;}. @xref{Recursion, ,Recursive
Rules}.
@item Left-to-right parsing
Parsing a sentence of a language by analyzing it token by token from
@@ -5372,7 +5407,8 @@ A token which consists of two or more fixed characters.
@xref{Symbols}.
@item Look-ahead token
A token already read but not yet shifted. @xref{Look-Ahead, ,Look-Ahead Tokens}.
A token already read but not yet shifted. @xref{Look-Ahead, ,Look-Ahead
Tokens}.
@item LALR(1)
The class of context-free grammars that Bison (like most other parser
@@ -5403,7 +5439,8 @@ performs some operation.
@item Reduction
Replacing a string of nonterminals and/or terminals with a single
nonterminal, according to a grammar rule. @xref{Algorithm, ,The Bison Parser Algorithm }.
nonterminal, according to a grammar rule. @xref{Algorithm, ,The Bison
Parser Algorithm }.
@item Reentrant
A reentrant subprogram is a subprogram which can be in invoked any
@@ -5414,8 +5451,9 @@ invocations. @xref{Pure Decl, ,A Pure (Reentrant) Parser}.
A language in which all operators are postfix operators.
@item Right recursion
A rule whose result symbol is also its last component symbol;
for example, @samp{expseq1: exp ',' expseq1;}. @xref{Recursion, ,Recursive Rules}.
A rule whose result symbol is also its last component symbol; for
example, @samp{expseq1: exp ',' expseq1;}. @xref{Recursion, ,Recursive
Rules}.
@item Semantics
In computer languages, the semantics are specified by the actions
@@ -5449,9 +5487,9 @@ The input of the Bison parser is a stream of tokens which comes from
the lexical analyzer. @xref{Symbols}.
@item Terminal symbol
A grammar symbol that has no rules in the grammar and therefore
is grammatically indivisible. The piece of text it represents
is a token. @xref{Language and Grammar, ,Languages and Context-Free Grammars}.
A grammar symbol that has no rules in the grammar and therefore is
grammatically indivisible. The piece of text it represents is a token.
@xref{Language and Grammar, ,Languages and Context-Free Grammars}.
@end table
@node Index, , Glossary, Top