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Diffstat (limited to 'contrib/byacc/NOTES-btyacc-Changes')
| -rw-r--r-- | contrib/byacc/NOTES-btyacc-Changes | 385 |
1 files changed, 0 insertions, 385 deletions
diff --git a/contrib/byacc/NOTES-btyacc-Changes b/contrib/byacc/NOTES-btyacc-Changes deleted file mode 100644 index f074907..0000000 --- a/contrib/byacc/NOTES-btyacc-Changes +++ /dev/null @@ -1,385 +0,0 @@ -Tom Shields, March 17, 2014 - -PARKING LOT ISSUES: -------------------- -- verify debian packaging still works? - -- there are no #line directives in y.tab.i, other than those that come - from the input file and the skeleton file; to fix this, would need to - count output lines in externs_file and add 'write_externs_lineno()' - similar to 'write_code_lineno()' -- if there are no defined symbols, the .tab.h file isn't empty (weird case, - may not be worth fixing) -- consider: treat []-actions identical to {}-actions if not processing a - backtracking parser (avoids test case error)? - - -BTYACC CHANGES CURRENTLY DEFERRED, BY FILE: -------------------------------------------- - -push.skel -- skeleton for a 'push' parser -- needs to be upgraded match the structure of yaccpar.skel - -defs.h -- adopt '%include' changes -- adopt '%define'/'%ifdef'/'%endif' -- adopt -E flag to print preprocessed grammar to stdout - -error.c -- adopt '%include' changes -- NOTE: there is a btyacc change that might be worth adopting in byacc - [FileError() refactoring to eliminate duplicated code in most of the - error message functions] - -main.c -- adopt '%define' changes -- adopt '-DNAME' command line option to define preprocessor variable NAME -- adopt -E flag to print preprocessed grammar to stdout -- adopt '-S skeleton_file' command line option to select an alternate parser - skeleton file -- the skeleton file named by the -S flag is used as provided to open the - file; consider a change to this behavior to check whether the named file - has a path prefix, and if not, look in 'installation' directory if the - file is not found in the working directory - -output.c -- adopt '%include' changes - -reader.c -- adopt '%include' changes -- adopt '%define'/'%ifdef'/'%endif' changes -- adopt -E flag to print preprocessed grammar to stdout -- NOTE: there is a btyacc change that might be worth adopting in byacc - [copy_string() & copy_comment() refactoring to eliminate duplicated - code in copy_text() and copy_union()] - -warshall.c -- NOTE: there is a btyacc change that might be worth adopting in byacc - [shifting 'mask' incrementally rather than literal '1' by a variable - amount each time thru the loop] - - -================================================================================ - - -new files: ----------- - -skel2c -- modified from btyacc distribution: don't generate #include defs.h -- extended syntax recognized to include '%% insert VERSION here', generating - the defines for YYMAJOR, YYMINOR and YYPATCH at that point -- made generated tables type 'const char *const' to match skelton.c from - byacc-20130925 baseline -- added code to append text for write_section() to end of generated skeleton.c -- remove conversion of tab to \t in generated skeleton.c -- extended syntax recognized to include '%%ifdef', '%%ifndef', '%%else' and - '%%endif'; used in yaccpar.skel to bracket code that is specific to - backtracking - -yaccpar.skel.old -- created from skeleton.c in byacc-20140101 baseline; use of this skeleton - will create a version of skeleton.c that is close to that in the - byacc-20140101 baseline -- eliminated 'body_3' and 'trailer_2' skeleton segments - no need to generate - yyerror() invocation dynamically; YYERROR_CALL() is already generated - earlier, and so can be used in the skeleton to simplify -- added 'const' to types in '%% tables' section to match what skel2c, - start_int_table() and state_str_table() generate -- added a few cosmetic changes (e.g., added some additional comments, - reworded debugging output to match yaccpar.skel, changed yygrowstack() - to return YYENOMEM for 'out of memory' error, rather than -1, to match - yaccpar.skel; changed yyparse() return value from 1 to 2 for the - 'out of memory' error to match yaccpar.skel) -- added '#ifndef'/'#endif' around '#define YYINITSTACKSIZE 200' to allow - the value to be changed at compile time -- changed 'printf(' to 'fprintf(stderr, '; added stack depth (yydepth) to - debugging output from yaccpar.skel -- use 'YYINT' rather than 'short' for integer table types - -yaccpar.skel -- renamed from btyaccpa.ske, merged with btyacc-c.ske -- modified from btyacc distribution to match the latest byacc-20140101 - skeleton structure & data structures -- make local functions static -- change "virtual memory exceeded" to "memory exhausted" for bison - compatibility -- change debug output generation from printf/puts/putc onto stdout to use - fprintf/fputs/fputc onto stderr; include - stack depth and whether or not in trial parsing -- changed types of generated string tables to be 'const pointer to const char' -- check all malloc()/realloc() return values, ensure return value of - yyparse() = 2 if parsing failed due to memory exhaustion -- change YYDBPR() macro to YYSTYPE_TOSTRING(); define semantics as delivering - a char* value representing a semantic value (e.g., yylval or yyval, or the - contents of an entry on the semantic stack); additional parameter passed: - grammar symbol # (to assist interpretation of semantic value) -- change YYPOSN to YYLTYPE and yyposn to yylloc (position corresponding to - yylval) for bison compatibility; add yyloc (corresponding to yyval) -- move default definition of YYLTYPE into output.c, generating a typedef -- add '#if defined(YYLTYPE) || defined(YYLTYPE_IS_DECLARED)'/'#endif' around - all lines specific to position processing -- add '#if defined(YYDESTRUCT_CALL)'/'#endif' around all lines specific to - semantic & position stack processing to reclaim memory associated with - discarded symbols -- add '%%ifdef YYBTYACC'/'%%endif' around all lines specific to backtrack - parsing; converted by skel2c into '#if defined(YYBTYACC)'/'#endif' -- distinguish between "yacc stack overflow" and "memory exhausted" situations -- consolidated termination cleanup code; introduced yyreturn, set to 2 after - labels yyoverflow/yyenomem, set to 1 after label yyabort, set to 0 after - label yyaccept; all termination cases jump to label yyreturn, which does - any cleanup then returns yyreturn value -- replaced YYDELETEVAL & YYDELETEPOSN user-supplied macro capability by - implementation of byacc-generated yydestruct() as defined by bison - compatible %destructor mechanism -- moved invocation of 'YYREDUCEPOSNFUNC' macro to immediately prior to, rather - than after, execution of final rule action (so that, at some future - date, implementation extensions can be added to enable custom calculation - of locations associated with non-terminals within rule actions); deleted - unnecessary flag 'reduce_posn'; deleted 'YYCALLREDUCEPOSN' macro; deleted - C++ variant of 'YYREDUCEPOSNFUNC' invocation -- adopt approach similar to bison for default computation of yyloc; change - macro 'YYREDUCEPOSNFUNC' name to 'YYLLOC_DEFAULT' for bison compatibility; - added 'yyerror_loc_range[2]' to hold start & end locations for error - situations that pop the stack -- use 'YYINT' rather than 'short' for integer table types, and for indexing - parser tables - -readskel.c -http://www.verisign.com/index.html- replaced error() with fprintf() - -mstring.h -- moved contents of mstring.h to defs.h - mstring.h is obsolete - -mstring.c -- replaced include of mstring.h with defs.h -- changed 'START' to 'HEAD' to remove conflict with 'START' used for - the start symbol defined in defs.h - -modified byacc files: ---------------------- - -skeleton.c -- skeleton.c is now generated from the appropriate skeleton file by 'skel2c' - -configure.in -- added configuration for --enable-btyacc option; if 'yes' add '-DYYBTYACC' - to DEFINES in makefile.in; --enable-btyacc defaults to 'no' -- added configuration for --with-max-table-size option; if present, - overrides the value of MAXTABLE defined in defs.h -- regenerate configure using autoconf - -makefile.in -- added mstring.c to C_FILES -- added mstring$o to OBJS -- added @DEFINES@ as value of DEFINES make variable -- added new make variable SKELETON with value 'yaccpar.skel' -- added rule to generate skeleton.c from $(SKELETON), depending on skel2c - and makefile -- added rm -f skeleton.c distclean rule -- moved dependency on makefile from only main$o & skeleton$o to $(OBJS), - since if ./configure is run changing, for example, from --enable-btyacc - to --disable-btyacc, all files must be recompiled to ensure a clean - executable -- add @MAXTABLE@ for optional '-DMAXTABLE=nnn' if configured using - --with-max-table-size=nnn -- changed 'cd test && rn 0f test-*'to 'rm -f $(testdir)/test-*' - -test/run_test.sh -- ??? - -test/run_make.sh -- ??? - -defs.h -- moved contents of mstring.h to defs.h - mstring.h is obsolete -- added <limits.h> to get the various system defined machine limits; - changed definitions of MAXCHAR, MAXSHORT, MINSHORT & BITS_PER_WORD to use - defines from <limits.h>; changed definitions of BIT and SETBIT to use - value of BITS_PER_WORD -- added typedef for __compar_fn_t, conditioned on _COMPAR_FN_T being - undefined (at least for Mac OSX environment) -- adopt new symbol class values ACTION and ARGUMENT -- adopt changes/additions used by inherited attribute processing -- clean up locations of extern function definitions to match where they - actually live in source files -- adopt error functions from inherited attribute processing; added new error - functions -- added keyword code LOCATIONS for %locations -- added keyword code DESTRUCTOR for %destructor -- added extern decl for 'int locations'; true if %locations present -- added extern decl for 'int backtrack'; initialized to 0 (= false), set to - 1 (= true) if -B flag is present -- added extern decl for 'int destructor'; true if at least one %destructor - present in grammar spec file -- define 'YYINT' as the smallest C type that can be used to address a - table of size 'MAXTABLE'; define 'YYINT' based on the value of - 'MAXTABLE' using the standard system type size definitions from <limits.h>; - define 'MAXYYINT' and 'MINYYINT' accordingly -- change 'Value_t' and 'Index_t' to 'YYINT' from 'short' -- allow 'MAXTABLE' to be defined by '-DMAXTABLE=nnn' at compile-time - -closure.c -- changed print_closure(), print_EFF() and print_first_derives() to 'static'; - added fwd declarations -- changed 'short' to 'Value_t' (in some instances, 'Value_t' was already - used for variables/parameters that were related to variables/parameters - declared as 'short' - -error.c -- adopt error functions from inherited attribute processing; added a few - additional inherited attribute error functions - -graph.c -- changed 'short' to 'Value_t' (in some instances, 'Value_t' was already - used for variables/parameters that were related to variables/parameters - declared as 'short' - -lalr.c -- changed MAXSHORT to MAXYYINT - -lr0.c -- changed MAXSHORT to MAXYYINT -- changed 'short' to 'Value_t' (in some instances, 'Value_t' was already - used for variables/parameters that were related to variables/parameters - declared as 'short' - -main.c -- changed 'short' to 'Value_t' (in some instances, 'Value_t' was already - used for variables/parameters that were related to variables/parameters - declared as 'short' - -mkpar.c -- backtracking attempts to resolve shift/reduce and reduce/reduce conflicts - -output.c -- generate prefix & YYPREFIX defines into externs file (-i, .tab.i) and - code file (-r, .code.c); generate into output file (.tab.c) only if not - using -r option; eliminates doubled output of prefix aliases if -r with - no -i in y.tab.c and y.code.c or if -r & -i in y.tab.i and y.code.c -- changed types of generated string tables to be 'const pointer to const char' -- adopt backtracking as an alternative in cases where otherwise we have a - conflict in the parsing actions (3, rather than 2, choices) -- wrap defines file with (where "yy" is value of 'symbol_prefix') - #ifndef __yy_defines_h_ - #define _yy_defines_h_ - - <defines> - - #endif -- avoid writing %%xdecls skeleton section twice if -r used -- eliminated 'body_3' and 'trailer_2' skeleton segments - no need to generate - yyerror() invocation dynamically; YYERROR_CALL() is already generated - earlier, and can be used in the pareser skeleton -- if -P flag (pure_parser), add yylloc as 2nd parameter to yylex() - (declaration & call) -- change YYPOSN to YYLTYPE and yyposn to yylloc (position corresponding to - yylval) for bison compatibility; add yyloc (corresponding to yyval) -- generate yylloc parameters for yylex & yyerror if %locations present -- add location as 1st parameter to declaraion & invocation of yyerror() if - %locations present -- output backtrack parsing tables if -B flag is present -- added generation of yystos[] with output_accessing_symbols() to allow - translation from a parser internal state number to the corresponding - grammar symbol number [0 .. nsyms) of the accessing symbol of that parser - state; used in the generated code for YYDESTRUCT_CALL() & - YYSTYPE_TOSTRING() to enable the correct semantic value union tag to be - determined when executing the implementation of YYDESTRUCT_CALL() or - YYSTYPE_TOSTRING() (similar to yystos[] in bison) -- added to output_prefix(): yystos; yycindex & yyctable if compiling - backtracking; yyloc & yylloc if %locations used -- extended yyname[] to include all grammar symbols, not just the terminal - symbols: '$end', 'error', '$accept', all non-terminals, including internally - generated non-terminals for embedded actions in rules, and 'illegal-symbol' - (which bison spells '$undefined'); '$end' already defined as a symbol 0, - rathern than adding 'end-of-file' as the name of symbol 0; added - 'illegal-symbol' from byacc-20140101 (NOTE: the comment in the code that - says byacc does not predefine '$end' and '$error' is incorrect; however, - both bison and byacc spell '$error' as 'error') -- added generation of #define YYTRANSLATE() from byacc-20140101, but changed - the definition for the undefined symbol case because it is no longer in - yyname[YYMAXTOKEN+1] but rather occurs after the last non-terminal symbol; - added #define YYUNDFTOKEN to contain the index in yyname of 'illegal-symbol' -- generate YYLTYPE in output_ltype() as a struct like for bison rather than - using #define in yaccpar.skel -- added 'write_code_lineno' invocation at start of 'output_prefix' -- added 'write_code_lineno' invocation at start of 'output_pure_parser' -- added 'write_code_lineno' invocation prior to generation of #include - for externs file -- added 'write_code_lineno' invocation after 1st 'write_section(fp, xdecls)' -- added '++outline;' prior to output of '#define YYTRANSLATE' - this was - actually causing almost all of the invocations of 'write_code_lineno' to - put out the correct #line directive -- corrected 'write_code_lineno' - the line number in a #line directive is - the number of the next line, not the number of the #line line -- changed MAXSHORT to MAXYYINT; changed 'high' local static from 'int' to - 'long' so that it can get higher than 'MAXYYINT' without machine-dependent - behavior; changed related formats from '%d' to '%ld' -- generate 'YYINT' rather than 'short' for integer table types -- generate YYDESTRUCT_DECL & YYDESTRUCT_CALL macros, similar to YYERROR_DECL - and YYERROR_CALL macros, that can be redefined by user, if desired, to add - additional parameters to yydestruct() (and even change the 'yydestruct' - function name) -- if at least one %destructor present, generate yydestruct(); 1st parameter - is a string indicating the context in which yydestruct() is invoked - (e.g., discarding input token, discarding state on stack, cleanup when - aborting); 2nd parameter is the internal grammar symbol number [0..nsyms) - of the accessing symbol of the parser state on the top of the stack; 3rd - parameter is a pointer to the semantic value to be reclaimed associated - with the grammar symbol in the 2nd parameter; if %locations is defined, - the 4th parameter is a pointer to the position value to be reclaimed - associated with the grammar symbol in the 2nd parameter - -reader.c -- adopt []-actions, similar to {}-actions; {}-actions are only executed when - not in trial mode, but []-actions are executed regardless of mode -- adopt new symbol class values ACTION and ARGUMENT -- adopt inherited attributes (syntax resembles arguments to non-terminal - symbols) -- adopt keyword table lookup from btyacc, modified to handle equivalence - of '-' and '_' in spelling of keywords -- adopt refactoring of tag table creation into cache_tag() for use in - multiple locations -- added new error functions in place of btyacc's generic error() function -- changed '0' to 'NULL' for pointer initialization -- reworked for-loop at end of get_line (part of DEFERRED '%ifdef/%endif' change) -- added %locations directive for bison compatibility to enable position - processing -- added decl for 'int locations'; true if %locations present -- added decl 'int backtrack'; initialized to 0 (= false), set to - 1 (= true) if -B flag is present -- process %locations if present, set location = 1 -- only process []-actions and only generate 'if (!yytrial)' prefix for - {}-actions if backtracking is enabled -- add decl for 'int destructor'; true if at least one %destructor is present -- add %destructor directive to enable semantic & position stack processing to - reclaim memory associated with discarded symbols -- process bison compatible %destructor (set destructor = 1); support @$ in - %destructor code to reference the position value if %locations is defined -- changed 'short' to 'Value_t' (in some instances, 'Value_t' was already - used for variables/parameters that were related to variables/parameters - declared as 'short' -- if %locations present, support @N and @$ syntax as for bison to reference - the locations associated with the N-th rhs symbol and the lhs symbol, - respectively - -symtab.c -- initialize fields added to 'struct bucket' for non-terminal symbol - inherited attributes - -verbose.c -- for parse states with conflicts, the contents of the y.output file include - the trial shift and/or trial reduce actions -- added output to the end of the verbose report showing the correspondance - between grammar symbol #, internal parser symbol #, and grammar symbol name -- changed 'short' to 'Value_t' (in some instances, 'Value_t' was already - used for variables/parameters that were related to variables/parameters - declared as 'short' - -yacc.1 -- added options 'P', 'V', 'y' and '-o output_file' to the yacc command - synopsis (already covered in the description section) -- added options 'B', 'D' and 'L' to the yacc command synopsis; added text in - the description section -- added %locations description to the extensions section |
