+2006-09-04 Joel E. Denny <jdenny@ces.clemson.edu>
+
+ Finish implementation of per-type %destructor/%printer. Discussed
+ starting at
+ <http://lists.gnu.org/archive/html/bison-patches/2006-02/msg00064.html>
+ and
+ <http://lists.gnu.org/archive/html/bison-patches/2006-06/msg00091.html>.
+ * NEWS (2.3+): Add a description of this feature to the default
+ %destructor/%printer description.
+ * doc/bison.texinfo (Freeing Discarded Symbols): Likewise.
+ * src/symlist.c (symbol_list_destructor_set, symbol_list_printer_set):
+ Invoke semantic_type_destructor_set or semantic_type_printer_set when a
+ list node contains a semantic type.
+ * src/symtab.c, src/symtab.h: Extend with a table that associates
+ semantic types with their %destructor's and %printer's.
+ (semantic_type_from_uniqstr, semantic_type_get,
+ semantic_type_destructor_set, semantic_type_printer_set): New functions
+ composing the public interface of that table.
+ (symbol_destructor_get, symbol_destructor_location_get,
+ symbol_printer_get, symbol_printer_location_get): If there's no
+ per-symbol %destructor/%printer, look up the per-type before trying
+ the default.
+ * tests/actions.at (Per-type %printer and %destructor): New test case.
+ * tests/input.at (Default %printer and %destructor redeclared):
+ Extend to check that multiple occurrences of %symbol-default in a
+ single %destructor/%printer declaration is an error.
+ (Per-type %printer and %destructor redeclared, Unused values with
+ per-type %destructor): New test cases.
+
2006-09-04 Joel E. Denny <jdenny@ces.clemson.edu>
Require default %destructor/%printer to be declared using
* Locations columns and lines start at 1.
In accordance with the GNU Coding Standards and Emacs.
-* You may now declare a default %destructor and %printer:
+* You may now declare per-type and default %destructor's and %printer's:
For example:
- %union { char *string; }
- %token <string> STRING1
- %token <string> STRING2
- %type <string> string1
- %type <string> string2
- %destructor { free ($$); } %symbol-default
- %destructor { free ($$); printf ("%d", @$.first_line); } STRING1 string1
-
- guarantees that, when the parser discards any user-defined symbol, it passes
- its semantic value to `free'. However, when the parser discards a `STRING1'
- or a `string1', it also prints its line number to `stdout'. It performs only
- the second `%destructor' in this case, so it invokes `free' only once.
+ %union { char *string; }
+ %token <string> STRING1
+ %token <string> STRING2
+ %type <string> string1
+ %type <string> string2
+ %union { char character; }
+ %token <character> CHR
+ %type <character> chr
+ %destructor { free ($$); } %symbol-default
+ %destructor { free ($$); printf ("%d", @$.first_line); } STRING1 string1
+ %destructor { } <character>
+
+ guarantees that, when the parser discards any user-defined symbol that has a
+ semantic type tag other than `<character>', it passes its semantic value to
+ `free'. However, when the parser discards a `STRING1' or a `string1', it
+ also prints its line number to `stdout'. It performs only the second
+ `%destructor' in this case, so it invokes `free' only once.
* Except for LALR(1) parsers in C with POSIX Yacc emulation enabled (with `-y',
`--yacc', or `%yacc'), Bison no longer generates #define statements for
with the discarded symbol, and @code{@@$} designates its location.
The additional parser parameters are also available (@pxref{Parser Function, ,
The Parser Function @code{yyparse}}).
-@end deffn
-@deffn {Directive} %destructor @{ @var{code} @} %symbol-default
-@cindex default %destructor
-@findex %symbol-default
-Invoke the braced @var{code} whenever the parser discards any user-defined
-grammar symbol for which the user has not specifically declared any
-@code{%destructor}.
-This is known as the default @code{%destructor}.
-As in the previous form, @code{$$}, @code{@@$}, and the additional parser
-parameters are available.
+When a symbol is listed among @var{symbols}, its @code{%destructor} is called a
+per-symbol @code{%destructor}.
+You may also define a per-type @code{%destructor} by listing a semantic type
+among @var{symbols}.
+In that case, the parser will invoke this @var{code} whenever it discards any
+grammar symbol that has that semantic type unless that symbol has its own
+per-symbol @code{%destructor}.
+
+Finally, you may define a default @code{%destructor} by placing
+@code{%symbol-default} in the @var{symbols} list of exactly one
+@code{%destructor} declaration in your grammar file.
+In that case, the parser will invoke the associated @var{code} whenever it
+discards any user-defined grammar symbol for which there is no per-type or
+per-symbol @code{%destructor}.
@end deffn
+@noindent
For instance:
@smallexample
%token <string> STRING2
%type <string> string1
%type <string> string2
+%union @{ char character; @}
+%token <character> CHR
+%type <character> chr
%destructor @{ free ($$); @} %symbol-default
%destructor @{ free ($$); printf ("%d", @@$.first_line); @} STRING1 string1
+%destructor @{ @} <character>
@end smallexample
@noindent
-guarantees that, when the parser discards any user-defined symbol, it passes
-its semantic value to @code{free}.
+guarantees that, when the parser discards any user-defined symbol that has a
+semantic type tag other than @code{<character>}, it passes its semantic value
+to @code{free}.
However, when the parser discards a @code{STRING1} or a @code{string1}, it also
prints its line number to @code{stdout}.
It performs only the second @code{%destructor} in this case, so it invokes
symbol_destructor_set (node->content.sym, destructor, loc);
break;
case SYMLIST_TYPE:
- /* FIXME: */
+ semantic_type_destructor_set (
+ semantic_type_get (node->content.type_name), destructor, loc);
break;
case SYMLIST_DEFAULT:
default_destructor_set (destructor, loc);
symbol_printer_set (node->content.sym, printer, loc);
break;
case SYMLIST_TYPE:
- /* FIXME: */
+ semantic_type_printer_set (
+ semantic_type_get (node->content.type_name), printer, loc);
break;
case SYMLIST_DEFAULT:
default_printer_set (printer, loc);
return res;
}
+/*----------------------------------------.
+| Create a new semantic type, named TAG. |
+`----------------------------------------*/
+
+static semantic_type *
+semantic_type_new (uniqstr tag)
+{
+ semantic_type *res = xmalloc (sizeof *res);
+
+ uniqstr_assert (tag);
+ res->tag = tag;
+ res->destructor = NULL;
+ res->printer = NULL;
+
+ return res;
+}
+
/*-----------------.
| Print a symbol. |
`------------------------------------------------------------------*/
static void
-redeclaration (symbol* s, const char *what, location first, location second)
+symbol_redeclaration (symbol *s, const char *what, location first,
+ location second)
{
complain_at (second, _("%s redeclaration for %s"), what, s->tag);
complain_at (first, _("previous declaration"));
}
+static void
+semantic_type_redeclaration (semantic_type *s, const char *what, location first,
+ location second)
+{
+ complain_at (second, _("%s redeclaration for <%s>"), what, s->tag);
+ complain_at (first, _("previous declaration"));
+}
+
/*-----------------------------------------------------------------.
| Set the TYPE_NAME associated with SYM. Does nothing if passed 0 |
if (type_name)
{
if (sym->type_name)
- redeclaration (sym, "%type", sym->type_location, loc);
+ symbol_redeclaration (sym, "%type", sym->type_location, loc);
uniqstr_assert (type_name);
sym->type_name = type_name;
sym->type_location = loc;
if (destructor)
{
if (sym->destructor)
- redeclaration (sym, "%destructor", sym->destructor_location, loc);
+ symbol_redeclaration (sym, "%destructor", sym->destructor_location,
+ loc);
sym->destructor = destructor;
sym->destructor_location = loc;
}
}
+/*-------------------------------------------------------------------.
+| Set the DESTRUCTOR associated with TYPE. Do nothing if passed 0. |
+`-------------------------------------------------------------------*/
+
+void
+semantic_type_destructor_set (semantic_type *type, const char *destructor,
+ location loc)
+{
+ if (destructor)
+ {
+ if (type->destructor)
+ semantic_type_redeclaration (type, "%destructor",
+ type->destructor_location, loc);
+ type->destructor = destructor;
+ type->destructor_location = loc;
+ }
+}
+
/*---------------------------------------.
| Get the computed %destructor for SYM. |
`---------------------------------------*/
if (sym->destructor != NULL)
return sym->destructor;
+ /* Per-type %destructor. */
+ if (sym->type_name)
+ {
+ semantic_type *type = semantic_type_get (sym->type_name);
+ if (type->destructor)
+ return type->destructor;
+ }
+
/* Apply the default %destructor only to user-defined symbols. */
if (sym->tag[0] == '$' || sym == errtoken)
return NULL;
{
if (sym->destructor != NULL)
return sym->destructor_location;
+ if (sym->type_name)
+ {
+ semantic_type *type = semantic_type_get (sym->type_name);
+ if (type->destructor)
+ return type->destructor_location;
+ }
return default_destructor_location;
}
if (printer)
{
if (sym->printer)
- redeclaration (sym, "%printer", sym->printer_location, loc);
+ symbol_redeclaration (sym, "%printer", sym->printer_location, loc);
sym->printer = printer;
sym->printer_location = loc;
}
}
+/*----------------------------------------------------------------.
+| Set the PRINTER associated with TYPE. Do nothing if passed 0. |
+`----------------------------------------------------------------*/
+
+void
+semantic_type_printer_set (semantic_type *type, const char *printer,
+ location loc)
+{
+ if (printer)
+ {
+ if (type->printer)
+ semantic_type_redeclaration (type, "%printer", type->printer_location,
+ loc);
+ type->printer = printer;
+ type->printer_location = loc;
+ }
+}
+
/*------------------------------------.
| Get the computed %printer for SYM. |
`------------------------------------*/
if (sym->printer != NULL)
return sym->printer;
+ /* Per-type %printer. */
+ if (sym->type_name)
+ {
+ semantic_type *type = semantic_type_get (sym->type_name);
+ if (type->printer)
+ return type->printer;
+ }
+
/* Apply the default %printer only to user-defined symbols. */
if (sym->tag[0] == '$' || sym == errtoken)
return NULL;
{
if (sym->printer != NULL)
return sym->printer_location;
+ if (sym->type_name)
+ {
+ semantic_type *type = semantic_type_get (sym->type_name);
+ if (type->printer)
+ return type->printer_location;
+ }
return default_printer_location;
}
if (a != undef_assoc)
{
if (sym->prec != 0)
- redeclaration (sym, assoc_to_string (a), sym->prec_location, loc);
+ symbol_redeclaration (sym, assoc_to_string (a), sym->prec_location,
+ loc);
sym->prec = prec;
sym->assoc = a;
sym->prec_location = loc;
}
-/*----------------------.
-| A symbol hash table. |
-`----------------------*/
+/*---------------------------------------.
+| Symbol and semantic type hash tables. |
+`---------------------------------------*/
-/* Initial capacity of symbols hash table. */
+/* Initial capacity of symbol and semantic type hash table. */
#define HT_INITIAL_CAPACITY 257
static struct hash_table *symbol_table = NULL;
+static struct hash_table *semantic_type_table = NULL;
static inline bool
hash_compare_symbol (const symbol *m1, const symbol *m2)
return UNIQSTR_EQ (m1->tag, m2->tag);
}
+static inline bool
+hash_compare_semantic_type (const semantic_type *m1, const semantic_type *m2)
+{
+ /* Since names are unique, we can compare the pointers themselves. */
+ return UNIQSTR_EQ (m1->tag, m2->tag);
+}
+
static bool
hash_symbol_comparator (void const *m1, void const *m2)
{
return hash_compare_symbol (m1, m2);
}
+static bool
+hash_semantic_type_comparator (void const *m1, void const *m2)
+{
+ return hash_compare_semantic_type (m1, m2);
+}
+
static inline size_t
hash_symbol (const symbol *m, size_t tablesize)
{
return ((uintptr_t) m->tag) % tablesize;
}
+static inline size_t
+hash_semantic_type (const semantic_type *m, size_t tablesize)
+{
+ /* Since names are unique, we can hash the pointer itself. */
+ return ((uintptr_t) m->tag) % tablesize;
+}
+
static size_t
hash_symbol_hasher (void const *m, size_t tablesize)
{
return hash_symbol (m, tablesize);
}
+static size_t
+hash_semantic_type_hasher (void const *m, size_t tablesize)
+{
+ return hash_semantic_type (m, tablesize);
+}
/*-------------------------------.
| Create the symbol hash table. |
hash_symbol_hasher,
hash_symbol_comparator,
free);
+ semantic_type_table = hash_initialize (HT_INITIAL_CAPACITY,
+ NULL,
+ hash_semantic_type_hasher,
+ hash_semantic_type_comparator,
+ free);
}
}
+/*-----------------------------------------------------------------------.
+| Find the semantic type named KEY, and return it. If it does not exist |
+| yet, create it. |
+`-----------------------------------------------------------------------*/
+
+semantic_type *
+semantic_type_from_uniqstr (const uniqstr key)
+{
+ semantic_type probe;
+ semantic_type *entry;
+
+ probe.tag = key;
+ entry = hash_lookup (semantic_type_table, &probe);
+
+ if (!entry)
+ {
+ /* First insertion in the hash. */
+ entry = semantic_type_new (key);
+ hash_insert (semantic_type_table, entry);
+ }
+ return entry;
+}
+
+
/*----------------------------------------------------------------.
| Find the symbol named KEY, and return it. If it does not exist |
| yet, create it. |
}
+/*-----------------------------------------------------------------------.
+| Find the semantic type named KEY, and return it. If it does not exist |
+| yet, create it. |
+`-----------------------------------------------------------------------*/
+
+semantic_type *
+semantic_type_get (const char *key)
+{
+ return semantic_type_from_uniqstr (uniqstr_new (key));
+}
+
+
/*------------------------------------------------------------------.
| Generate a dummy nonterminal, whose name cannot conflict with the |
| user's names. |
symbols_free (void)
{
hash_free (symbol_table);
+ hash_free (semantic_type_table);
free (symbols);
}
bool declared;
};
-
/** Undefined user number. */
#define USER_NUMBER_UNDEFINED -1
extern location startsymbol_location;
-/*---------------.
-| Symbol table. |
-`---------------*/
+/*-----------------.
+| Semantic types. |
+`-----------------*/
+
+/** A semantic type and its associated \c \%destructor and \c \%printer.
+
+ Access the fields of this struct only through the interface functions in
+ this file. \sa symbol::destructor */
+typedef struct semantic_type {
+ /** The key, name of the semantic type. */
+ uniqstr tag;
+
+ /** Any \c %destructor declared for this semantic type. */
+ const char *destructor;
+ /** The location of \c semantic_type::destructor. */
+ location destructor_location;
+
+ /** Any \c %printer declared for this semantic type. */
+ const char *printer;
+ /** The location of \c semantic_type::printer. */
+ location printer_location;
+} semantic_type;
+
+/** Fetch (or create) the semantic type associated to KEY. */
+semantic_type *semantic_type_from_uniqstr (const uniqstr key);
+
+/** Fetch (or create) the semantic type associated to KEY. */
+semantic_type *semantic_type_get (const char *key);
+
+/** Set the \c destructor associated with \c type. */
+void semantic_type_destructor_set (semantic_type *type, const char *destructor,
+ location loc);
+
+/** Set the \c printer associated with \c type. */
+void semantic_type_printer_set (semantic_type *type, const char *printer,
+ location loc);
+/*----------------------------------.
+| Symbol and semantic type tables. |
+`----------------------------------*/
-/** Create the symbol table. */
+/** Create the symbol and semantic type tables. */
void symbols_new (void);
-/** Free all the memory allocated for symbols. */
+/** Free all the memory allocated for symbols and semantic types. */
void symbols_free (void);
/** Check that all the symbols are defined.
+## ----------------------------------- ##
+## Per-type %printer and %destructor. ##
+## ----------------------------------- ##
+
+AT_SETUP([Per-type %printer and %destructor])
+
+AT_DATA_GRAMMAR([[input.y]],
+[[%error-verbose
+%debug
+
+%{
+# include <stdio.h>
+# include <stdlib.h>
+ static void yyerror (const char *msg);
+ static int yylex (void);
+# define USE(SYM)
+%}
+
+%union { int field0; int field1; int field2; }
+%type <field0> start 'a' 'g'
+%type <field1> 'e'
+%type <field2> 'f'
+%printer {
+ fprintf (yyoutput, "%%symbol-default/<field2>/e printer");
+} %symbol-default 'e' <field2>
+%destructor {
+ fprintf (stdout, "%%symbol-default/<field2>/e destructor.\n");
+} %symbol-default 'e' <field2>
+
+%type <field1> 'b'
+%printer { fprintf (yyoutput, "<field1> printer"); } <field1>
+%destructor { fprintf (stdout, "<field1> destructor.\n"); } <field1>
+
+%type <field0> 'c'
+%printer { fprintf (yyoutput, "'c' printer"); } 'c'
+%destructor { fprintf (stdout, "'c' destructor.\n"); } 'c'
+
+%type <field1> 'd'
+%printer { fprintf (yyoutput, "'d' printer"); } 'd'
+%destructor { fprintf (stdout, "'d' destructor.\n"); } 'd'
+
+%%
+
+start:
+ 'a' 'b' 'c' 'd' 'e' 'f' 'g'
+ {
+ USE(($1, $2, $3, $4, $5, $6, $7));
+ $$ = 'S';
+ }
+ ;
+
+%%
+
+static int
+yylex (void)
+{
+ static const char *input = "abcdef";
+ return *input++;
+}
+
+static void
+yyerror (const char *msg)
+{
+ fprintf (stderr, "%s\n", msg);
+}
+
+int
+main (void)
+{
+ yydebug = 1;
+ return yyparse ();
+}
+]])
+
+AT_CHECK([bison -o input.c input.y])
+AT_COMPILE([input])
+AT_PARSER_CHECK([./input], 1,
+[[%symbol-default/<field2>/e destructor.
+%symbol-default/<field2>/e destructor.
+'d' destructor.
+'c' destructor.
+<field1> destructor.
+%symbol-default/<field2>/e destructor.
+]],
+[[Starting parse
+Entering state 0
+Reading a token: Next token is token 'a' (%symbol-default/<field2>/e printer)
+Shifting token 'a' (%symbol-default/<field2>/e printer)
+Entering state 1
+Reading a token: Next token is token 'b' (<field1> printer)
+Shifting token 'b' (<field1> printer)
+Entering state 3
+Reading a token: Next token is token 'c' ('c' printer)
+Shifting token 'c' ('c' printer)
+Entering state 5
+Reading a token: Next token is token 'd' ('d' printer)
+Shifting token 'd' ('d' printer)
+Entering state 6
+Reading a token: Next token is token 'e' (%symbol-default/<field2>/e printer)
+Shifting token 'e' (%symbol-default/<field2>/e printer)
+Entering state 7
+Reading a token: Next token is token 'f' (%symbol-default/<field2>/e printer)
+Shifting token 'f' (%symbol-default/<field2>/e printer)
+Entering state 8
+Reading a token: Now at end of input.
+syntax error, unexpected $end, expecting 'g'
+Error: popping token 'f' (%symbol-default/<field2>/e printer)
+Stack now 0 1 3 5 6 7
+Error: popping token 'e' (%symbol-default/<field2>/e printer)
+Stack now 0 1 3 5 6
+Error: popping token 'd' ('d' printer)
+Stack now 0 1 3 5
+Error: popping token 'c' ('c' printer)
+Stack now 0 1 3
+Error: popping token 'b' (<field1> printer)
+Stack now 0 1
+Error: popping token 'a' (%symbol-default/<field2>/e printer)
+Stack now 0
+Cleanup: discarding lookahead token $end ()
+Stack now 0
+]])
+
+AT_CLEANUP
+
+
+
## ------------------------------------------------------------- ##
## Default %printer and %destructor for user-defined end token. ##
## ------------------------------------------------------------- ##
AT_SETUP([Default %printer and %destructor redeclared])
AT_DATA([[input.y]],
-[[%destructor { destroy ($$); } %symbol-default
-%printer { destroy ($$); } %symbol-default
+[[%destructor { destroy ($$); } %symbol-default %symbol-default
+%printer { destroy ($$); } %symbol-default %symbol-default
%destructor { destroy ($$); } %symbol-default
%printer { destroy ($$); } %symbol-default
]])
AT_CHECK([bison input.y], [1], [],
-[[input.y:4.13-29: redeclaration for default %destructor
+[[input.y:1.13-29: redeclaration for default %destructor
+input.y:1.13-29: previous declaration
+input.y:2.10-26: redeclaration for default %printer
+input.y:2.10-26: previous declaration
+input.y:4.13-29: redeclaration for default %destructor
input.y:1.13-29: previous declaration
input.y:5.10-26: redeclaration for default %printer
input.y:2.10-26: previous declaration
AT_CLEANUP
+## ---------------------------------------------- ##
+## Per-type %printer and %destructor redeclared. ##
+## ---------------------------------------------- ##
+
+AT_SETUP([Per-type %printer and %destructor redeclared])
+
+AT_DATA([[input.y]],
+[[%destructor { destroy ($$); } <field1> <field2>
+%printer { destroy ($$); } <field1> <field2>
+
+%destructor { destroy ($$); } <field1> <field1>
+%printer { destroy ($$); } <field2> <field2>
+
+%%
+
+start: ;
+
+%destructor { destroy ($$); } <field2> <field1>;
+%printer { destroy ($$); } <field2> <field1>;
+]])
+
+AT_CHECK([bison input.y], [1], [],
+[[input.y:4.13-29: %destructor redeclaration for <field1>
+input.y:1.13-29: previous declaration
+input.y:4.13-29: %destructor redeclaration for <field1>
+input.y:4.13-29: previous declaration
+input.y:5.10-26: %printer redeclaration for <field2>
+input.y:2.10-26: previous declaration
+input.y:5.10-26: %printer redeclaration for <field2>
+input.y:5.10-26: previous declaration
+input.y:11.13-29: %destructor redeclaration for <field1>
+input.y:4.13-29: previous declaration
+input.y:11.13-29: %destructor redeclaration for <field2>
+input.y:1.13-29: previous declaration
+input.y:12.10-26: %printer redeclaration for <field1>
+input.y:2.10-26: previous declaration
+input.y:12.10-26: %printer redeclaration for <field2>
+input.y:5.10-26: previous declaration
+]])
+
+AT_CLEANUP
+
+
## ---------------------------------------- ##
## Unused values with default %destructor. ##
## ---------------------------------------- ##
AT_CLEANUP
+## ----------------------------------------- ##
+## Unused values with per-type %destructor. ##
+## ----------------------------------------- ##
+
+AT_SETUP([Unused values with per-type %destructor])
+
+AT_DATA([[input.y]],
+[[%destructor { destroy ($$); } <field1>
+%type <field1> start end
+
+%%
+
+start: end end { $1; } ;
+end: { } ;
+]])
+
+AT_CHECK([bison input.y], [0], [],
+[[input.y:6.8-22: warning: unset value: $$
+input.y:6.8-22: warning: unused value: $2
+input.y:7.6-8: warning: unset value: $$
+]])
+
+AT_CLEANUP
+
+
## ---------------------- ##
## Incompatible Aliases. ##
## ---------------------- ##
projects / bison.git / commitdiff
