0c8de5b03c
Among all the modifications, this new byacc also solves a 14 year old bug [1] PR: bin/23254 [1] Submitted by: marka@nominum.com [1] MFC after: 3 weeks
386 lines
18 KiB
Plaintext
386 lines
18 KiB
Plaintext
Tom Shields, March 17, 2014
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PARKING LOT ISSUES:
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-------------------
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- verify debian packaging still works?
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- there are no #line directives in y.tab.i, other than those that come
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from the input file and the skeleton file; to fix this, would need to
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count output lines in externs_file and add 'write_externs_lineno()'
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similar to 'write_code_lineno()'
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- if there are no defined symbols, the .tab.h file isn't empty (weird case,
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may not be worth fixing)
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- consider: treat []-actions identical to {}-actions if not processing a
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backtracking parser (avoids test case error)?
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BTYACC CHANGES CURRENTLY DEFERRED, BY FILE:
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-------------------------------------------
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push.skel
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- skeleton for a 'push' parser
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- needs to be upgraded match the structure of yaccpar.skel
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defs.h
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- adopt '%include' changes
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- adopt '%define'/'%ifdef'/'%endif'
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- adopt -E flag to print preprocessed grammar to stdout
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error.c
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- adopt '%include' changes
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- NOTE: there is a btyacc change that might be worth adopting in byacc
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[FileError() refactoring to eliminate duplicated code in most of the
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error message functions]
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main.c
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- adopt '%define' changes
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- adopt '-DNAME' command line option to define preprocessor variable NAME
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- adopt -E flag to print preprocessed grammar to stdout
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- adopt '-S skeleton_file' command line option to select an alternate parser
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skeleton file
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- the skeleton file named by the -S flag is used as provided to open the
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file; consider a change to this behavior to check whether the named file
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has a path prefix, and if not, look in 'installation' directory if the
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file is not found in the working directory
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output.c
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- adopt '%include' changes
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reader.c
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- adopt '%include' changes
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- adopt '%define'/'%ifdef'/'%endif' changes
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- adopt -E flag to print preprocessed grammar to stdout
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- NOTE: there is a btyacc change that might be worth adopting in byacc
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[copy_string() & copy_comment() refactoring to eliminate duplicated
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code in copy_text() and copy_union()]
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warshall.c
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- NOTE: there is a btyacc change that might be worth adopting in byacc
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[shifting 'mask' incrementally rather than literal '1' by a variable
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amount each time thru the loop]
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================================================================================
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new files:
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----------
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skel2c
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- modified from btyacc distribution: don't generate #include defs.h
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- extended syntax recognized to include '%% insert VERSION here', generating
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the defines for YYMAJOR, YYMINOR and YYPATCH at that point
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- made generated tables type 'const char *const' to match skelton.c from
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byacc-20130925 baseline
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- added code to append text for write_section() to end of generated skeleton.c
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- remove conversion of tab to \t in generated skeleton.c
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- extended syntax recognized to include '%%ifdef', '%%ifndef', '%%else' and
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'%%endif'; used in yaccpar.skel to bracket code that is specific to
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backtracking
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yaccpar.skel.old
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- created from skeleton.c in byacc-20140101 baseline; use of this skeleton
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will create a version of skeleton.c that is close to that in the
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byacc-20140101 baseline
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- eliminated 'body_3' and 'trailer_2' skeleton segments - no need to generate
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yyerror() invocation dynamically; YYERROR_CALL() is already generated
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earlier, and so can be used in the skeleton to simplify
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- added 'const' to types in '%% tables' section to match what skel2c,
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start_int_table() and state_str_table() generate
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- added a few cosmetic changes (e.g., added some additional comments,
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reworded debugging output to match yaccpar.skel, changed yygrowstack()
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to return YYENOMEM for 'out of memory' error, rather than -1, to match
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yaccpar.skel; changed yyparse() return value from 1 to 2 for the
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'out of memory' error to match yaccpar.skel)
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- added '#ifndef'/'#endif' around '#define YYINITSTACKSIZE 200' to allow
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the value to be changed at compile time
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- changed 'printf(' to 'fprintf(stderr, '; added stack depth (yydepth) to
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debugging output from yaccpar.skel
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- use 'YYINT' rather than 'short' for integer table types
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yaccpar.skel
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- renamed from btyaccpa.ske, merged with btyacc-c.ske
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- modified from btyacc distribution to match the latest byacc-20140101
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skeleton structure & data structures
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- make local functions static
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- change "virtual memory exceeded" to "memory exhausted" for bison
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compatibility
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- change debug output generation from printf/puts/putc onto stdout to use
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fprintf/fputs/fputc onto stderr; include
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stack depth and whether or not in trial parsing
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- changed types of generated string tables to be 'const pointer to const char'
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- check all malloc()/realloc() return values, ensure return value of
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yyparse() = 2 if parsing failed due to memory exhaustion
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- change YYDBPR() macro to YYSTYPE_TOSTRING(); define semantics as delivering
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a char* value representing a semantic value (e.g., yylval or yyval, or the
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contents of an entry on the semantic stack); additional parameter passed:
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grammar symbol # (to assist interpretation of semantic value)
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- change YYPOSN to YYLTYPE and yyposn to yylloc (position corresponding to
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yylval) for bison compatibility; add yyloc (corresponding to yyval)
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- move default definition of YYLTYPE into output.c, generating a typedef
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- add '#if defined(YYLTYPE) || defined(YYLTYPE_IS_DECLARED)'/'#endif' around
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all lines specific to position processing
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- add '#if defined(YYDESTRUCT_CALL)'/'#endif' around all lines specific to
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semantic & position stack processing to reclaim memory associated with
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discarded symbols
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- add '%%ifdef YYBTYACC'/'%%endif' around all lines specific to backtrack
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parsing; converted by skel2c into '#if defined(YYBTYACC)'/'#endif'
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- distinguish between "yacc stack overflow" and "memory exhausted" situations
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- consolidated termination cleanup code; introduced yyreturn, set to 2 after
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labels yyoverflow/yyenomem, set to 1 after label yyabort, set to 0 after
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label yyaccept; all termination cases jump to label yyreturn, which does
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any cleanup then returns yyreturn value
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- replaced YYDELETEVAL & YYDELETEPOSN user-supplied macro capability by
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implementation of byacc-generated yydestruct() as defined by bison
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compatible %destructor mechanism
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- moved invocation of 'YYREDUCEPOSNFUNC' macro to immediately prior to, rather
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than after, execution of final rule action (so that, at some future
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date, implementation extensions can be added to enable custom calculation
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of locations associated with non-terminals within rule actions); deleted
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unnecessary flag 'reduce_posn'; deleted 'YYCALLREDUCEPOSN' macro; deleted
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C++ variant of 'YYREDUCEPOSNFUNC' invocation
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- adopt approach similar to bison for default computation of yyloc; change
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macro 'YYREDUCEPOSNFUNC' name to 'YYLLOC_DEFAULT' for bison compatibility;
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added 'yyerror_loc_range[2]' to hold start & end locations for error
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situations that pop the stack
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- use 'YYINT' rather than 'short' for integer table types, and for indexing
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parser tables
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readskel.c
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http://www.verisign.com/index.html- replaced error() with fprintf()
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mstring.h
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- moved contents of mstring.h to defs.h - mstring.h is obsolete
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mstring.c
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- replaced include of mstring.h with defs.h
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- changed 'START' to 'HEAD' to remove conflict with 'START' used for
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the start symbol defined in defs.h
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modified byacc files:
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---------------------
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skeleton.c
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- skeleton.c is now generated from the appropriate skeleton file by 'skel2c'
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configure.in
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- added configuration for --enable-btyacc option; if 'yes' add '-DYYBTYACC'
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to DEFINES in makefile.in; --enable-btyacc defaults to 'no'
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- added configuration for --with-max-table-size option; if present,
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overrides the value of MAXTABLE defined in defs.h
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- regenerate configure using autoconf
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makefile.in
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- added mstring.c to C_FILES
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- added mstring$o to OBJS
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- added @DEFINES@ as value of DEFINES make variable
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- added new make variable SKELETON with value 'yaccpar.skel'
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- added rule to generate skeleton.c from $(SKELETON), depending on skel2c
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and makefile
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- added rm -f skeleton.c distclean rule
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- moved dependency on makefile from only main$o & skeleton$o to $(OBJS),
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since if ./configure is run changing, for example, from --enable-btyacc
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to --disable-btyacc, all files must be recompiled to ensure a clean
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executable
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- add @MAXTABLE@ for optional '-DMAXTABLE=nnn' if configured using
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--with-max-table-size=nnn
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- changed 'cd test && rn 0f test-*'to 'rm -f $(testdir)/test-*'
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test/run_test.sh
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- ???
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test/run_make.sh
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- ???
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defs.h
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- moved contents of mstring.h to defs.h - mstring.h is obsolete
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- added <limits.h> to get the various system defined machine limits;
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changed definitions of MAXCHAR, MAXSHORT, MINSHORT & BITS_PER_WORD to use
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defines from <limits.h>; changed definitions of BIT and SETBIT to use
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value of BITS_PER_WORD
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- added typedef for __compar_fn_t, conditioned on _COMPAR_FN_T being
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undefined (at least for Mac OSX environment)
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- adopt new symbol class values ACTION and ARGUMENT
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- adopt changes/additions used by inherited attribute processing
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- clean up locations of extern function definitions to match where they
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actually live in source files
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- adopt error functions from inherited attribute processing; added new error
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functions
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- added keyword code LOCATIONS for %locations
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- added keyword code DESTRUCTOR for %destructor
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- added extern decl for 'int locations'; true if %locations present
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- added extern decl for 'int backtrack'; initialized to 0 (= false), set to
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1 (= true) if -B flag is present
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- added extern decl for 'int destructor'; true if at least one %destructor
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present in grammar spec file
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- define 'YYINT' as the smallest C type that can be used to address a
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table of size 'MAXTABLE'; define 'YYINT' based on the value of
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'MAXTABLE' using the standard system type size definitions from <limits.h>;
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define 'MAXYYINT' and 'MINYYINT' accordingly
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- change 'Value_t' and 'Index_t' to 'YYINT' from 'short'
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- allow 'MAXTABLE' to be defined by '-DMAXTABLE=nnn' at compile-time
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closure.c
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- changed print_closure(), print_EFF() and print_first_derives() to 'static';
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added fwd declarations
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- changed 'short' to 'Value_t' (in some instances, 'Value_t' was already
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used for variables/parameters that were related to variables/parameters
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declared as 'short'
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error.c
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- adopt error functions from inherited attribute processing; added a few
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additional inherited attribute error functions
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graph.c
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- changed 'short' to 'Value_t' (in some instances, 'Value_t' was already
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used for variables/parameters that were related to variables/parameters
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declared as 'short'
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lalr.c
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- changed MAXSHORT to MAXYYINT
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lr0.c
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- changed MAXSHORT to MAXYYINT
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- changed 'short' to 'Value_t' (in some instances, 'Value_t' was already
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used for variables/parameters that were related to variables/parameters
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declared as 'short'
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main.c
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- changed 'short' to 'Value_t' (in some instances, 'Value_t' was already
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used for variables/parameters that were related to variables/parameters
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declared as 'short'
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mkpar.c
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- backtracking attempts to resolve shift/reduce and reduce/reduce conflicts
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output.c
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- generate prefix & YYPREFIX defines into externs file (-i, .tab.i) and
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code file (-r, .code.c); generate into output file (.tab.c) only if not
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using -r option; eliminates doubled output of prefix aliases if -r with
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no -i in y.tab.c and y.code.c or if -r & -i in y.tab.i and y.code.c
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- changed types of generated string tables to be 'const pointer to const char'
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- adopt backtracking as an alternative in cases where otherwise we have a
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conflict in the parsing actions (3, rather than 2, choices)
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- wrap defines file with (where "yy" is value of 'symbol_prefix')
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#ifndef __yy_defines_h_
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#define _yy_defines_h_
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<defines>
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#endif
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- avoid writing %%xdecls skeleton section twice if -r used
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- eliminated 'body_3' and 'trailer_2' skeleton segments - no need to generate
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yyerror() invocation dynamically; YYERROR_CALL() is already generated
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earlier, and can be used in the pareser skeleton
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- if -P flag (pure_parser), add yylloc as 2nd parameter to yylex()
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(declaration & call)
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- change YYPOSN to YYLTYPE and yyposn to yylloc (position corresponding to
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yylval) for bison compatibility; add yyloc (corresponding to yyval)
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- generate yylloc parameters for yylex & yyerror if %locations present
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- add location as 1st parameter to declaraion & invocation of yyerror() if
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%locations present
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- output backtrack parsing tables if -B flag is present
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- added generation of yystos[] with output_accessing_symbols() to allow
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translation from a parser internal state number to the corresponding
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grammar symbol number [0 .. nsyms) of the accessing symbol of that parser
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state; used in the generated code for YYDESTRUCT_CALL() &
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YYSTYPE_TOSTRING() to enable the correct semantic value union tag to be
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determined when executing the implementation of YYDESTRUCT_CALL() or
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YYSTYPE_TOSTRING() (similar to yystos[] in bison)
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- added to output_prefix(): yystos; yycindex & yyctable if compiling
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backtracking; yyloc & yylloc if %locations used
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- extended yyname[] to include all grammar symbols, not just the terminal
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symbols: '$end', 'error', '$accept', all non-terminals, including internally
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generated non-terminals for embedded actions in rules, and 'illegal-symbol'
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(which bison spells '$undefined'); '$end' already defined as a symbol 0,
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rathern than adding 'end-of-file' as the name of symbol 0; added
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'illegal-symbol' from byacc-20140101 (NOTE: the comment in the code that
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says byacc does not predefine '$end' and '$error' is incorrect; however,
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both bison and byacc spell '$error' as 'error')
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- added generation of #define YYTRANSLATE() from byacc-20140101, but changed
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the definition for the undefined symbol case because it is no longer in
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yyname[YYMAXTOKEN+1] but rather occurs after the last non-terminal symbol;
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added #define YYUNDFTOKEN to contain the index in yyname of 'illegal-symbol'
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- generate YYLTYPE in output_ltype() as a struct like for bison rather than
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using #define in yaccpar.skel
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- added 'write_code_lineno' invocation at start of 'output_prefix'
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- added 'write_code_lineno' invocation at start of 'output_pure_parser'
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- added 'write_code_lineno' invocation prior to generation of #include
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for externs file
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- added 'write_code_lineno' invocation after 1st 'write_section(fp, xdecls)'
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- added '++outline;' prior to output of '#define YYTRANSLATE' - this was
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actually causing almost all of the invocations of 'write_code_lineno' to
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put out the correct #line directive
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- corrected 'write_code_lineno' - the line number in a #line directive is
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the number of the next line, not the number of the #line line
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- changed MAXSHORT to MAXYYINT; changed 'high' local static from 'int' to
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'long' so that it can get higher than 'MAXYYINT' without machine-dependent
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behavior; changed related formats from '%d' to '%ld'
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- generate 'YYINT' rather than 'short' for integer table types
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- generate YYDESTRUCT_DECL & YYDESTRUCT_CALL macros, similar to YYERROR_DECL
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and YYERROR_CALL macros, that can be redefined by user, if desired, to add
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additional parameters to yydestruct() (and even change the 'yydestruct'
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function name)
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- if at least one %destructor present, generate yydestruct(); 1st parameter
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is a string indicating the context in which yydestruct() is invoked
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(e.g., discarding input token, discarding state on stack, cleanup when
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aborting); 2nd parameter is the internal grammar symbol number [0..nsyms)
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of the accessing symbol of the parser state on the top of the stack; 3rd
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parameter is a pointer to the semantic value to be reclaimed associated
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with the grammar symbol in the 2nd parameter; if %locations is defined,
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the 4th parameter is a pointer to the position value to be reclaimed
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associated with the grammar symbol in the 2nd parameter
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reader.c
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- adopt []-actions, similar to {}-actions; {}-actions are only executed when
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not in trial mode, but []-actions are executed regardless of mode
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- adopt new symbol class values ACTION and ARGUMENT
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- adopt inherited attributes (syntax resembles arguments to non-terminal
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symbols)
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- adopt keyword table lookup from btyacc, modified to handle equivalence
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of '-' and '_' in spelling of keywords
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- adopt refactoring of tag table creation into cache_tag() for use in
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multiple locations
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- added new error functions in place of btyacc's generic error() function
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- changed '0' to 'NULL' for pointer initialization
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- reworked for-loop at end of get_line (part of DEFERRED '%ifdef/%endif' change)
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- added %locations directive for bison compatibility to enable position
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processing
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- added decl for 'int locations'; true if %locations present
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- added decl 'int backtrack'; initialized to 0 (= false), set to
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1 (= true) if -B flag is present
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- process %locations if present, set location = 1
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- only process []-actions and only generate 'if (!yytrial)' prefix for
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{}-actions if backtracking is enabled
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- add decl for 'int destructor'; true if at least one %destructor is present
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- add %destructor directive to enable semantic & position stack processing to
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reclaim memory associated with discarded symbols
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- process bison compatible %destructor (set destructor = 1); support @$ in
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%destructor code to reference the position value if %locations is defined
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- changed 'short' to 'Value_t' (in some instances, 'Value_t' was already
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used for variables/parameters that were related to variables/parameters
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declared as 'short'
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- if %locations present, support @N and @$ syntax as for bison to reference
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the locations associated with the N-th rhs symbol and the lhs symbol,
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respectively
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symtab.c
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- initialize fields added to 'struct bucket' for non-terminal symbol
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inherited attributes
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verbose.c
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- for parse states with conflicts, the contents of the y.output file include
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the trial shift and/or trial reduce actions
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- added output to the end of the verbose report showing the correspondance
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between grammar symbol #, internal parser symbol #, and grammar symbol name
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- changed 'short' to 'Value_t' (in some instances, 'Value_t' was already
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used for variables/parameters that were related to variables/parameters
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declared as 'short'
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yacc.1
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- added options 'P', 'V', 'y' and '-o output_file' to the yacc command
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synopsis (already covered in the description section)
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- added options 'B', 'D' and 'L' to the yacc command synopsis; added text in
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the description section
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- added %locations description to the extensions section
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