src/scan-code.h

   1 /* Bison code properties structure and scanner.
   2
   3    Copyright (C) 2006-2007, 2009-2015, 2018-2020 Free Software
   4    Foundation, Inc.
   5
   6    This file is part of Bison, the GNU Compiler Compiler.
   7
   8    This program is free software: you can redistribute it and/or modify
   9    it under the terms of the GNU General Public License as published by
  10    the Free Software Foundation, either version 3 of the License, or
  11    (at your option) any later version.
  12
  13    This program is distributed in the hope that it will be useful,
  14    but WITHOUT ANY WARRANTY; without even the implied warranty of
  15    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  16    GNU General Public License for more details.
  17
  18    You should have received a copy of the GNU General Public License
  19    along with this program.  If not, see <http://www.gnu.org/licenses/>.  */
  20
  21 #ifndef SCAN_CODE_H_
  22 # define SCAN_CODE_H_
  23
  24 # include "location.h"
  25 # include "named-ref.h"
  26 # include "uniqstr.h"
  27
  28 struct symbol_list;
  29
  30 /**
  31  * Keeps track of the maximum number of semantic values to the left of a handle
  32  * (those referenced by $0, $-1, etc.) that are required by the semantic
  33  * actions of this grammar.
  34  */
  35 extern int max_left_semantic_context;
  36
  37 /**
  38  * A code passage captured from the grammar file and possibly translated,
  39  * and/or properties associated with such a code passage.  Don't break
  40  * encapsulation by modifying the fields directly.  Use the provided interface
  41  * functions.
  42  */
  43 typedef struct code_props {
  44   /** Set by the init functions.  */
  45   enum {
  46     CODE_PROPS_NONE, CODE_PROPS_PLAIN,
  47     CODE_PROPS_SYMBOL_ACTION, CODE_PROPS_RULE_ACTION
  48   } kind;
  49
  50   /**
  51    * \c NULL iff \c code_props::kind is \c CODE_PROPS_NONE.
  52    * Memory is allocated in an obstack freed elsewhere.
  53    */
  54   char const *code;
  55   /** Undefined iff \c code_props::code is \c NULL.  */
  56   location location;
  57
  58   /**
  59    * \c false iff either:
  60    *   - \c code_props_translate_code has never previously been invoked for
  61    *     the \c code_props that would contain the code passage associated
  62    *     with \c self.  (That \c code_props is not the same as this one if this
  63    *     one is for a RHS \c symbol_list node.  Instead, it's the \c code_props
  64    *     for the LHS symbol of the same rule.)
  65    *   - \c code_props_translate_code has been invoked for that \c code_props,
  66    *     but the symbol value associated with this \c code_props was not
  67    *     referenced in the code passage.
  68    */
  69   bool is_value_used;
  70
  71   /**
  72    * \c true iff this code is an action that is not to be deferred in
  73    * a non-deterministic parser.
  74    */
  75   bool is_predicate;
  76
  77   /**
  78    * Whether this is actually used (i.e., not completely masked by
  79    * other code props).  */
  80   bool is_used;
  81
  82   /** \c NULL iff \c code_props::kind is not \c CODE_PROPS_RULE_ACTION.  */
  83   struct symbol_list *rule;
  84
  85   /** Named reference. */
  86   named_ref *named_ref;
  87
  88   /** Type, for midrule actions.  */
  89   uniqstr type;
  90 } code_props;
  91
  92 /**
  93  * \pre
  94  *   - <tt>self != NULL</tt>.
  95  * \post
  96  *   - \c self has been overwritten to contain no code.
  97  */
  98 void code_props_none_init (code_props *self);
  99
 100 /** Equivalent to \c code_props_none_init.  */
 101 # define CODE_PROPS_NONE_INIT                   \
 102   {                                             \
 103     /* .kind = */ CODE_PROPS_NONE,              \
 104     /* .code = */ NULL,                         \
 105     /* .location = */ EMPTY_LOCATION_INIT,      \
 106     /* .is_value_used = */ false,               \
 107     /* .is_predicate = */ false,                \
 108     /* .is_used = */ false,                     \
 109     /* .rule = */ NULL,                         \
 110     /* .named_ref = */ NULL,                    \
 111     /* .type = */ NULL,                         \
 112   }
 113
 114 /** Initialized by \c CODE_PROPS_NONE_INIT with no further modification.  */
 115 extern code_props code_props_none;
 116
 117 /**
 118  * \pre
 119  *   - <tt>self != NULL</tt>.
 120  *   - <tt>code != NULL</tt>.
 121  *   - \c code is an untranslated code passage containing no Bison escapes.
 122  *   - \c code was extracted from the grammar file at \c code_loc.
 123  * \post
 124  *   - \c self has been overwritten to represent the specified plain code
 125  *     passage.
 126  *   - \c self will become invalid if the caller frees \c code before invoking
 127  *     \c code_props_translate_code on \c self.
 128  */
 129 void code_props_plain_init (code_props *self, char const *code,
 130                             location code_loc);
 131
 132 /**
 133  * \pre
 134  *   - <tt>self != NULL</tt>.
 135  *   - <tt>code != NULL</tt>.
 136  *   - \c code is an untranslated code passage.  The only Bison escapes it
 137  *     might contain are $$ and \@$, referring to a single symbol.
 138  *   - \c code was extracted from the grammar file at \c code_loc.
 139  * \post
 140  *   - \c self has been overwritten to represent the specified symbol action.
 141  *   - \c self will become invalid if the caller frees \c code before invoking
 142  *     \c code_props_translate_code on \c self.
 143  */
 144 void code_props_symbol_action_init (code_props *self, char const *code,
 145                                     location code_loc);
 146
 147 /**
 148  * \param  type   type for midrule actions
 149  * \pre
 150  *   - <tt>self != NULL</tt>.
 151  *   - <tt>code != NULL</tt>.
 152  *   - <tt>rule != NULL</tt>.
 153  *   - \c code is the untranslated action of the rule for which \c rule is the
 154  *     LHS node.  Thus, \c code possibly contains Bison escapes such as $$, $1,
 155  *     $2, etc referring to the values of the rule.
 156  *   - \c code was extracted from the grammar file at \c code_loc.
 157  * \post
 158  *   - \c self has been overwritten to represent the specified rule action.
 159  *   - \c self does not claim responsibility for the memory of \c rule.
 160  *   - \c self will become invalid if:
 161  *     - The caller frees \c code before invoking \c code_props_translate_code
 162  *       on \c self.
 163  *     - The caller frees \c rule.
 164  */
 165 void code_props_rule_action_init (code_props *self, char const *code,
 166                                   location code_loc, struct symbol_list *rule,
 167                                   named_ref *name, uniqstr type,
 168                                   bool is_predicate);
 169
 170 /**
 171  * \pre
 172  *   - If there's a code passage contained in \c self and it contains Bison
 173  *     escapes, all grammar declarations have already been parsed as they may
 174  *     affect warnings and complaints issued here.
 175  * \post
 176  *   - All M4-special symbols and Bison escapes have been translated in
 177  *     \c self->code.
 178  *   - <tt>self->code != self->code\@pre</tt> unless
 179  *     <tt>self->code\@pre = NULL</tt>.
 180  */
 181 void code_props_translate_code (code_props *self);
 182
 183 /**
 184  * \pre
 185  *   - None.
 186  * \post
 187  *   - The dynamic memory allocated by the previous invocation of
 188  *     \c code_props_translate_code (if any) was freed.  The \c code_props
 189  *     instance for which \c code_props_translate_code was invoked is now
 190  *     invalid.
 191  */
 192 void code_scanner_last_string_free (void);
 193
 194 /**
 195  * \pre
 196  *   - None.
 197  * \post
 198  *   - All dynamic memory allocated during invocations of
 199  *     \c code_props_translate_code (if any) has been freed.  All \c code_props
 200  *     instances may now be invalid.
 201  */
 202 void code_scanner_free (void);
 203
 204 #endif /* !SCAN_CODE_H_ */