Prompted on Piotr Marcińczyk's message:
http://lists.gnu.org/archive/html/bug-bison/2017-06/msg00000.html.
See also http://lists.gnu.org/archive/html/bug-bison/2018-06/msg00001.html.
Because their type is unknown to Bison, the values of midrule actions are
not treated like the others: they don't have %printer and %destructor
support. In addition, in C++, (Bison) variants cannot work properly.
Typed midrule actions address these issues. Instead of:
exp: { $<ival>$ = 1; } { $<ival>$ = 2; } { $$ = $<ival>1 + $<ival>2; }
write:
exp: <ival>{ $$ = 1; } <ival>{ $$ = 2; } { $$ = $1 + $2; }
* src/scan-code.h, src/scan-code.l (code_props): Add a `type` field to
record the declared type of an action.
(code_props_rule_action_init): Add a type argument.
* src/parse-gram.y: Accept an optional type tag for actions.
* src/reader.h, src/reader.c (grammar_current_rule_action_append): Add
a type argument.
(grammar_midrule_action): When a mid-rule is typed, pass its type to
the defined dummy non terminal symbol.
* origin/maint: (29 commits)
regen
synclines: remove spurious empty line
also support $<foo>$ in the %initial-action
skeletons: b4_dollar_pushdef and popdef to simpify complex definitions
regen
printer/destructor: translate only once
factor the handling of m4 escaping
news: schedule the removal of the ";" hack
style changes in the scanners
regen
support $<tag>$ in printers and destructors
scan-code: factor the handling of the type in $<TYPE>$
muscles: fix another occurrence of unescaped type name
glr.cc: fix the handling of yydebug
gnulib: update
formatting changes
tests: fix an assertion
tests: adjust to GCC 4.8, which displays caret errors
be sure to properly escape type names
obstack_quote: escape and quote for M4
muscles: shuffle responsabilities
muscles: make private functions static
muscles: rename private functions/macros
obstack_escape: escape M4 characters
remove dead macro
maint: style changes
doc: avoid problems with case insensitive file systems
configure: fix botched quoting
news: fix typo.
Conflicts:
NEWS
data/c.m4
data/glr.cc
data/lalr1.cc
examples/rpcalc/local.mk
src/muscle-tab.h
src/output.c
src/parse-gram.c
src/parse-gram.h
src/parse-gram.y
src/scan-code.l
src/symlist.c
src/symlist.h
src/symtab.h
tests/calc.at
Currently "%printer {...} a b c d e f" translates the {...} six times.
Not only is this bad for time and space, it also issues six times the
same warnings.
* src/symlist.h, src/symlist.c (symbol_list_destructor_set)
(symbol_list_printer_set): Take the action as code_props instead of
const char *.
* src/parse-gram.y: Translate these actions here.
* src/scan-code.h: Comment change.
* tests/input.at: Check that warnings are issued only once.
The logic to compute the %printer or %destructor to used (i.e., a
code_props) is implemented twice: one, of course, in
symbol_code_props_get, and another time in symbol_check_defined to
record the fact that a code_props is used (so that we can reported
unused ones). Let the former use the latter.
I would probably use "mutable" in C++ and keep these guys const,
but this is C. And casting away constness triggers warnings.
* src/scan-code.h, src/scan-code.l (code_props_none): Is not const.
* src/symtab.h, src/symtab.c (symbol_code_props_get): The symbol
is not const.
(symbol_check_defined): Use it.
* src/scan-code.h (code_props): Add field 'is_used'.
(CODE_PROPS_NONE_INIT): Adjust.
* src/scan-code.l (code_props_plain_init, code_props_symbol_action_init)
(code_props_rule_action_init): Instead of implementing several
times the initialization of the code_props structures,
use code_props_none_init.
* src/symtab.c (symbol_check_defined): If a symbol does not have a
destructor (resp. printer) but has a type which has a destructor (resp.
printer), then set field 'is_used' to true.
(semantic_type_check_defined): If a type has a destructor (resp. printer)
but all symbols of this type have already a destructor (resp. printer),
then raise a warning.
* tests/input.at (Useless printers or destructors): New.
Signed-off-by: Akim Demaille <akim@lrde.epita.fr>
These changes allow users to prefix an action with %? to indicate that it
is a semantic predicate---an expression that is evaluated immediately (not
deferred, even in GLR nondeterministic mode) and causes a syntax error if
false. In GLR parsers, this has the effect of killing one of a set of
split-off parses, just as would an ordinary syntax error.
Changelog:
* NEWS: Describe new semantic-predicate feature.
* data/c.m4 (b4_predicate_case): New definition.
* data/java.m4 (b4_predicate_case): New definition.
* data/glr.c (yyimmediate): Add definition.
(yydoAction): Remove comment, now obsolete.
Do YY_REDUCE_PRINT here.
(yyglrReduce): Alter comment to indicate that semantic values
need not be deferred.
Remove YY_REDUCE_PRINT from here; done in yydoAction.
(yyprocessOneStack): Pass immediate flag.
Delete stacks rejected by predicates in newly split-off parsers.
Change handling of yyerr so that only current stack gets deleted
when semantic predicate fails.
(yyfillin): Don't crash if a semantic value is unresolved (as may
happen in predicate rules).
Copy lr state as well in debugging mode.
Update comment on setting of yysval to include yyloc as well.
(yy_reduce_print): Add yynormal argument. Perform fillin properly.
Report unresolved RHS values.
(yyimmediate): New table.
* src/gram.h (struct rule): Add is_predicate field.
* src/output.c (user_actions_output): Use b4_predicate_case for
predicates.
(prepare_symbols): Output yyimmediate.
* src/scan-gram.l: Add %? token, SC_PREDICATE state.
* src/scan-code.l (code_props_rule_action_init): Add is_predicate
argument.
* src/scan-code.h (struct code_props): Add is_predicate field.
(code_props_rule_action_init): New interface.
* src/parse-gram.y (%?{...}): New token.
(rhs): Add %?{...} rule.
* src/parse-gram.c: Regenerate.
* src/parse-gram.h: Regenerate.
* src/reader.c (grammar_current_rule_action_append): Add
immediate argument.
(grammar_midrule_action): Use new interface for
code_props_rule_action_init.
(grammar_current_rule_action_append): Ditto.
(packgram): Transfer is_predicate value.
* src/reader.h (grammar_current_rule_action_append): New interface.
* doc/bison.texinfo: Document semantic predicates (%?).
* data/glr.c (yylhsNonterm, yyisDefaultedState,yyDefaultAction)
(yygetLRActions,yynewGLRStackItem,yyaddDeferredAction,yyinitStateSet)
(yyinitGLRStack,yyexpandGLRStack,yyupdateSplit,yymarkStackDeleted)
(yyundeleteLastStack,yyglrShift,yyglrShiftDefer,yydoAction,yyglrReduce)
(yyidenticalOptions,yymergeOptionSets,yyresolveStates,yyresolveAction)
(yyresolveLocations,yyresolveValue,yyreducePrint): Update parameter
names in comments and mention all parameters.
(struct yyGLRState): Fix description of yyposn field.
(yyresolveLocations): Correct comment so as not to imply action when
yyn1==0.
Discussed in:
http://lists.gnu.org/archive/html/bison-patches/2009-01/msg00000.htmlhttp://lists.gnu.org/archive/html/bison-patches/2009-02/msg00002.htmlhttp://lists.gnu.org/archive/html/bison-patches/2009-03/msg00009.html
* src/parse-gram.y: Add new syntax (named_ref.opt).
* src/reader.c: Store named refs in symbol lists.
* src/reader.h: New argument for symbol_append and
action_append functions.
* src/scan-code.h: Add new field (named_ref) into
code_props data structure. Keeps named ref of midrule
actions.
* src/scan-code.l: Support for named refs in semantic
action code. New function 'parse_named_ref'.
* src/scan-gram.l: Support bracketed id.
* src/symlist.c: Store named refs in symbol lists.
* src/symlist.h: New field in symbol list: named_ref.
* src/named-ref.h: New file, a struct for named_ref.
* src/named-ref.c: New file, named_ref_new function.
* src/Makefile.am: Add two new files.
* tests/testsuite.at: Include new test group:
* tests/named-refs.at: this new file.
Discussed in:
http://lists.gnu.org/archive/html/bison-patches/2009-01/msg00000.htmlhttp://lists.gnu.org/archive/html/bison-patches/2009-02/msg00002.htmlhttp://lists.gnu.org/archive/html/bison-patches/2009-03/msg00009.html
* src/parse-gram.y: Add new syntax (named_ref.opt).
* src/reader.c: Store named refs in symbol lists.
* src/reader.h: New argument for symbol_append and
action_append functions.
* src/scan-code.h: Add new field (named_ref) into
code_props data structure. Keeps named ref of midrule
actions.
* src/scan-code.l: Support for named refs in semantic
action code. New function 'parse_named_ref'.
* src/scan-gram.l: Support bracketed id.
* src/symlist.c: Store named refs in symbol lists.
* src/symlist.h: New field in symbol list: named_ref.
* src/named-ref.h: New file, a struct for named_ref.
* src/named-ref.cp: New file, named_ref_new function.
* src/local.mk: Add two new files.
* tests/testsuite.at: Include new test group:
* tests/named-refs.at: this new file.
* src/parse-gram.y (prologue_declaration, braceless, epilogue.opt):
Update all uses of translate_* functions to use the new code_props
interface and to use gram_scanner_last_string_free and
code_scanner_last_string_free where possible.
(grammar_declaration): symbol_list_destructor_set and
symbol_list_printer_set now perform the translation, so don't do it
here. Use gram_scanner_last_string_free where possible.
* src/scan-code.h, src/scan-code.l (translate_symbol_action,
translate_code): Remove, no longer used.
* src/symlist.h, src/symlist.c (symbol_list_destructor_set,
symbol_list_printer_set): Perform code translation here rather than
depending on the caller to do so.
* src/symlist.h (struct symbol_list): Correct some documentation typos.
* src/scan-gram.h (gram_last_string): Remove declaration.
* src/scan-gram.l (last_string): Declare it static.
destructors, printers, and actions into a code_props structure and
interface. This patch merely implements code_props in scan-code.h and
scan-code.l. Future patches will rewrite other modules to use it.
Discussed starting at
<http://lists.gnu.org/archive/html/bison-patches/2006-11/msg00020.html>.
* src/location.h (EMPTY_LOCATION_INIT): Define so that it's easier to
consistently initialize const structs that have an empty location
field.
* src/location.c (empty_location): Initialize with EMPTY_LOCATION_INIT
to ensure consistency.
* src/scan-code.h (code_props): New structure.
(code_props_none_init, CODE_PROPS_NONE_INIT, code_props_none): New
function, macro, and const global variable for initializing a
code_props with no code.
(code_props_plain_init, code_props_symbol_action_init,
code_props_rule_action_init, code_props_translate_code): The rest of
the new code_props functional interface. Among other things, the init
functions set the code_props kind field so that
code_props_translate_code will know whether to behave like
translate_symbol_action, translate_rule_action, or translate_code.
These old translate functions must remain until all other modules are
updated to use the new code_props interface.
(code_scanner_last_string_free): New function similar to
gram_scanner_last_string_free.
(code_scanner_free): Add documentation.
* src/scan-code.l: Implement the new interface.
(code_lex): Make it static, add a code_props* argument, and remove the
rule argument.
(last_string): New static global similar to the one in scan-gram.l.
(SC_RULE_ACTION): Update to use the code_props* argument to code_lex
instead of rule.
(SC_SYMBOL_ACTION): For $$, set the is_value_used member of the
code_props since Bison may one day use this information for destructors
and printers.
(<*><<EOF>>): Use STRING_FINISH so that last_string is set.
(handle_action_dollar): Use symbol_list_n_get and set used flag
directly since symbol_list_n_used_set is removed.
(translate_action): Add a code_props* argument and remove the rule,
action, and location arguments. Pass the code_props* on to code_lex.
(translate_rule_action, translate_symbol_action, translate_code):
Rewrite as wrappers around the new code_props interface.
* src/symlist.h, src/symlist.c (symbol_list_n_used_set): Remove since
it would eventually need to break the encapsulation of code_props.
destructors, printers, and actions into a code_props structure and
interface.
* src/location.h (EMPTY_LOCATION_INIT): Define so that it's easier to
consistently initialize const structs that have an empty location field.
* src/location.c (empty_location): Initialize with EMPTY_LOCATION_INIT
to ensure consistency.
* src/output.c (symbol_destructors_output, symbol_printers_output):
Replace with...
(symbol_code_props_output): ... this to eliminate duplicate code.
(output_skeleton): Update to use symbol_code_props_output.
* src/parse-gram.y (prologue_declaration, braceless, epilogue.opt):
Update all uses of translate_* functions to use the new code_props
interface and to use gram_scanner_last_string_free and
code_scanner_last_string_free where possible.
(grammar_declaration): symbol_list_destructor_set and
symbol_list_printer_set now perform the translation, so don't do it
here. Use gram_scanner_last_string_free where possible.
* src/reader.c: Update to use code_props interface for destructors and
rule actions.
* src/scan-code.h (code_props): New structure.
(code_props_none_init, CODE_PROPS_NONE_INIT, code_props_none): New
function, macro, and const global variable for initializing a
code_props with no code.
(code_props_plain_init, code_props_symbol_action_init,
code_props_rule_action_init, code_props_translate_code,
code_props_code_get, code_props_location_get,
code_props_is_value_used): The rest of the new code_props interface.
(translate_rule_action, translate_symbol_action, translate_code):
Remove as these are now just special cases within
code_props_translate_code, which is switched on the code_props kind.
(code_scanner_last_string_free): New function similar to
gram_scanner_last_string_free.
* src/scan-code.l: Implement the new interface.
(last_string): New static global similar to the one in scan-gram.l.
(SC_SYMBOL_ACTION): For $$, set the is_value_used member of the
code_props since Bison will one day use this information for
destructors and printers.
(<*><<EOF>>): Use STRING_FINISH so that last_string is set.
(handle_action_dollar): Update to use the code_props interface of rule
actions. Use symbol_list_n_get and set is_value_used directly since
symbol_list_n_used_set is removed.
* src/symlist.h, src/symlist.c (symbol_list): Replace action,
action_location, and used members with a code_props member, and update
all uses.
(symbol_list_n_used_set): Remove since it would need to break the
encapsulation of code_props.
(symbol_list_destructor_set, symbol_list_printer_set): Perform code
translation here rather than depending on the caller to do so.
* src/symtab.h (symbol, semantic_type): Remove destructor_location and
printer_location members and change the type of the destructor and
printer members to code_props.
(symbol_destructor_location_get, symbol_printer_location_get): Remove
unneeded.
(symbol_destructor_set, symbol_destructor_get, symbol_printer_set,
symbol_printer_get, semantic_type_destructor_set,
semantic_type_printer_set, default_tagged_destructor_set,
default_tagless_destructor_set, default_tagged_printer_set,
default_tagless_printer_set): Use code_props in arguments and return
types in place of const char * and location.
* src/symtab.c: Update implementation for interface and struct changes.
(default_tagged_destructor_location,
default_tagless_destructor_location, default_tagged_printer_location,
default_tagless_printer_location): Remove since we...
(default_tagged_destructor, default_tagless_destructor,
default_tagged_printer, default_tagless_printer): ... change the type
of these to code_props.
(SYMBOL_CODE_PRINT): New similar to SYMBOL_ATTR_PRINT but for
code_props members.
(symbol_print): Use SYMBOL_CODE_PRINT.
* src/scan-gram.h (gram_last_string): Remove declaration.
* src/scan-gram.l (last_string): Declare it static.
* src/files.h (parser_file_name, spec_verbose_file, spec_graph_file):
(spec_defines_file, dir_prefix): Now char *, not const char *,
since they are freed.
* src/files.c: Likewise.
(all_but_ext, all_but_tab_ext, src_extension, header_extension):
Likewise.
(tr): Now operates in-place. All uses changed.
(compute_exts_from_gf, compute_exts_from_src): Don't leak temporary
values.
(compute_file_name_parts, compute_output_file_names): Don't store
read-only data in variables that will be freed.
(compute_output_file_names): Free all_but_ext, all_but_tab_ext,
src_extension, and header_extension.
(output_file_names_free): New public function to free
spec_verbose_file, spec_graph_file, spec_defines_file,
parser_file_name, and dir_prefix.
* src/getargs.c (getargs): Don't store read-only data in variables that
will be freed.
* src/main.c (main): Invoke output_file_names_free, code_scanner_free
(which previously existed but was unused), and quotearg_free.
* src/muscle_tab.h (muscle_insert): value arg is now a `char const *'.
* src/muscle_tab.c: Likewise.
(muscle_entry): Make the value char const *,
and add a new storage member that is char * and can be freed.
(muscle_entry_free): New private function.
(muscle_init): Use it instead of free.
(muscle_insert, muscle_grow): Update and use new storage member.
(muscle_code_grow): Free the string passed to muscle_grow
since it's not needed anymore.
* src/parse-gram.y (%union): Make `chars' member a `char const *', and
add a new `char *code' member.
("{...}"): Declare semantic type as code.
* src/scan-code.h (translate_rule_action):
(translate_symbol_action, translate_code, translate_action): Return
`char const *' rather than `char *' since external code should not free
these strings.
* src/scan-code.l: Likewise.
* src/scan-gram.l (<SC_BRACED_CODE>): Use val->code for BRACED_CODE,
which is "{...}" in the parser.
* tests/Makefile.am (maintainer-check-valgrind): Set
VALGRIND_OPTS='--leak-check=full --show-reacheable=yes' before invoking
Valgrind.
* tests/calc.at (_AT_DATA_CALC_Y): fclose the FILE* so Valgrind doesn't
complain.
* tests/testsuite.at (AT_CHECK): Redefine so that running Bison and
expecting a non-zero exit status sets --leak-check=summary and
--show-reachable=no for Valgrind. Bison unabashedly leaks memory in
this case, and we don't want to hear about it.
* src/scan-code.h, src/scan-code.l (translate_action)
(translate_rule_action, translate_symbol_action, translate_code):
Return char *, not const char *.
* src/parse-gram.y (declaration): Rename as...
(prologue_declaration): this.
(string_content): Remove this nonterminal, use STRING.
(braceless, content, content.opt): New nonterminal.
Use them.
(%define): Now accept content.opt, i.e., accept also BRACED_CODE
as value.
* src/scan-gram.l (getargs.h): Don't include it.
As a consequence, the relation between the grammar scanner and
parser is much simpler. We can also split "composite tokens" back
into simple tokens.
* src/gram.h (ITEM_NUMBER_MAX, RULE_NUMBER_MAX): New.
* src/scan-gram.l (add_column_width, adjust_location): Move to and
rename as...
* src/location.h, src/location.c (add_column_width)
(location_compute): these.
Fix the column count: the initial column is 0.
(location_print): Be robust to ending column being 0.
* src/location.h (boundary_set): New.
* src/main.c: Adjust to scanner_free being renamed as
gram_scanner_free.
* src/output.c: Include scan-code.h.
* src/parse-gram.y: Include scan-gram.h and scan-code.h.
Use boundary_set.
(PERCENT_DESTRUCTOR, PERCENT_PRINTER, PERCENT_INITIAL_ACTION)
(PERCENT_LEX_PARAM, PERCENT_PARSE_PARAM): Remove the {...} part,
which is now, again, a separate token.
Adjust all dependencies.
Whereever actions with $ and @ are used, use translate_code.
(action): Remove this nonterminal which is now useless.
* src/reader.c: Include assert.h, scan-gram.h and scan-code.h.
(grammar_current_rule_action_append): Use translate_code.
(packgram): Bound check ruleno, itemno, and rule_length.
* src/reader.h (gram_in, gram__flex_debug, scanner_cursor)
(last_string, last_braced_code_loc, max_left_semantic_context)
(scanner_initialize, scanner_free, scanner_last_string_free)
(gram_out, gram_lineno, YY_DECL_): Move to...
* src/scan-gram.h: this new file.
(YY_DECL): Rename as...
(GRAM_DECL): this.
* src/scan-code.h, src/scan-code.l, src/scan-code-c.c: New.
* src/scan-gram.l (gram_get_lineno, gram_get_in, gram_get_out):
(gram_get_leng, gram_get_text, gram_set_lineno, gram_set_in):
(gram_set_out, gram_get_debug, gram_set_debug, gram_lex_destroy):
Move these declarations, and...
(obstack_for_string, STRING_GROW, STRING_FINISH, STRING_FREE):
these to...
* src/flex-scanner.h: this new file.
* src/scan-gram.l (rule_length, rule_length_overflow)
(increment_rule_length): Remove.
(last_braced_code_loc): Rename as...
(gram_last_braced_code_loc): this.
Adjust to the changes of the parser.
Move all the handling of $ and @ into...
* src/scan-code.l: here.
* src/scan-gram.l (handle_dollar, handle_at): Remove.
(handle_action_dollar, handle_action_at): Move to...
* src/scan-code.l: here.
* src/Makefile.am (bison_SOURCES): Add flex-scanner.h,
scan-code.h, scan-code-c.c, scan-gram.h.
(EXTRA_bison_SOURCES): Add scan-code.l.
(BUILT_SOURCES): Add scan-code.c.
(yacc): Be robust to white spaces.
* tests/conflicts.at, tests/input.at, tests/reduce.at,
* tests/regression.at: Adjust the column numbers.
* tests/regression.at: Adjust the error message.
