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[bison.git] / src / scan-code.h

/* Bison code properties structure and scanner.

   Copyright (C) 2006, 2007, 2009, 2010 Free Software Foundation, Inc.

   This file is part of Bison, the GNU Compiler Compiler.

   This program is free software: you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published by
   the Free Software Foundation, either version 3 of the License, or
   (at your option) any later version.

   This program is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   GNU General Public License for more details.

   You should have received a copy of the GNU General Public License
   along with this program.  If not, see <http://www.gnu.org/licenses/>.  */

#ifndef SCAN_CODE_H_
# define SCAN_CODE_H_

# include "location.h"
# include "named-ref.h"

struct symbol_list;

/**
 * Keeps track of the maximum number of semantic values to the left of a handle
 * (those referenced by $0, $-1, etc.) that are required by the semantic
 * actions of this grammar.
 */
extern int max_left_semantic_context;

/**
 * A code passage captured from the grammar file and possibly translated,
 * and/or properties associated with such a code passage.  Don't break
 * encapsulation by modifying the fields directly.  Use the provided interface
 * functions.
 */
typedef struct code_props {
  /** Set by the init functions.  */
  enum {
    CODE_PROPS_NONE, CODE_PROPS_PLAIN,
    CODE_PROPS_SYMBOL_ACTION, CODE_PROPS_RULE_ACTION
  } kind;

  /** \c NULL iff \c code_props::kind is \c CODE_PROPS_NONE.  */
  char const *code;
  /** Undefined iff \c code_props::code is \c NULL.  */
  location location;

  /**
   * \c false iff either:
   *   - \c code_props_translate_code has never previously been invoked for
   *     the \c code_props that would contain the code passage associated
   *     with \c self.  (That \c code_props is not the same as this one if this
   *     one is for a RHS \c symbol_list node.  Instead, it's the \c code_props
   *     for the LHS symbol of the same rule.)
   *   - \c code_props_translate_code has been invoked for that \c code_props,
   *     but the symbol value associated with this \c code_props was not
   *     referenced in the code passage.
   */
  bool is_value_used;

  /** \c NULL iff \c code_props::kind is not \c CODE_PROPS_RULE_ACTION.  */
  struct symbol_list *rule;

  /* Named reference. */
  named_ref *named_ref;
} code_props;

/**
 * \pre
 *   - <tt>self != NULL</tt>.
 * \post
 *   - \c self has been overwritten to contain no code.
 */
void code_props_none_init (code_props *self);

/** Equivalent to \c code_props_none_init.  */
#define CODE_PROPS_NONE_INIT \
  {CODE_PROPS_NONE, NULL, EMPTY_LOCATION_INIT, false, NULL, NULL}

/** Initialized by \c CODE_PROPS_NONE_INIT with no further modification.  */
extern code_props const code_props_none;

/**
 * \pre
 *   - <tt>self != NULL</tt>.
 *   - <tt>code != NULL</tt>.
 *   - \c code is an untranslated code passage containing no Bison escapes.
 *   - \c code was extracted from the grammar file at \c code_loc.
 * \post
 *   - \c self has been overwritten to represent the specified plain code
 *     passage.
 *   - \c self will become invalid if the caller frees \c code before invoking
 *     \c code_props_translate_code on \c self.
 */
void code_props_plain_init (code_props *self, char const *code,
                            location code_loc);

/**
 * \pre
 *   - <tt>self != NULL</tt>.
 *   - <tt>code != NULL</tt>.
 *   - \c code is an untranslated code passage.  The only Bison escapes it
 *     might contain are $$ and \@$, referring to a single symbol.
 *   - \c code was extracted from the grammar file at \c code_loc.
 * \post
 *   - \c self has been overwritten to represent the specified symbol action.
 *   - \c self will become invalid if the caller frees \c code before invoking
 *     \c code_props_translate_code on \c self.
 */
void code_props_symbol_action_init (code_props *self, char const *code,
                                    location code_loc);

/**
 * \pre
 *   - <tt>self != NULL</tt>.
 *   - <tt>code != NULL</tt>.
 *   - <tt>rule != NULL</tt>.
 *   - \c code is the untranslated action of the rule for which \c rule is the
 *     LHS node.  Thus, \c code possibly contains Bison escapes such as $$, $1,
 *     $2, etc referring to the values of the rule.
 *   - \c code was extracted from the grammar file at \c code_loc.
 * \post
 *   - \c self has been overwritten to represent the specified rule action.
 *   - \c self does not claim responsibility for the memory of \c rule.
 *   - \c self will become invalid if:
 *     - The caller frees \c code before invoking \c code_props_translate_code
 *       on \c self.
 *     - The caller frees \c rule.
 */
void code_props_rule_action_init (code_props *self, char const *code,
                                  location code_loc, struct symbol_list *rule,
                                  named_ref *name);

/**
 * \pre
 *   - If there's a code passage contained in \c self and it contains Bison
 *     escapes, all grammar declarations have already been parsed as they may
 *     affect warnings and complaints issued here.
 * \post
 *   - All M4-special symbols and Bison escapes have been translated in
 *     \c self->code.
 *   - <tt>self->code != self->code\@pre</tt> unless
 *     <tt>self->code\@pre = NULL</tt>.
 */
void code_props_translate_code (code_props *self);

/**
 * \pre
 *   - None.
 * \post
 *   - The dynamic memory allocated by the previous invocation of
 *     \c code_props_translate_code (if any) was freed.  The \c code_props
 *     instance for which \c code_props_translate_code was invoked is now
 *     invalid.
 */
void code_scanner_last_string_free (void);

/**
 * \pre
 *   - None.
 * \post
 *   - All dynamic memory allocated during invocations of
 *     \c code_props_translate_code (if any) has been freed.  All \c code_props
 *     instances may now be invalid.
 */
void code_scanner_free (void);

#endif /* !SCAN_CODE_H_ */