/* Definitions for using variables in GNU Make.
Copyright (C) 1988, 1989, 1990, 1991, 1992 Free Software Foundation, Inc.
This file is part of GNU Make.

GNU Make 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 2, or (at your option)
any later version.

GNU Make 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 GNU Make; see the file COPYING.  If not, write to
the Free Software Foundation, 675 Mass Ave, Cambridge, MA 02139, USA.  */

/* Codes in a variable definition saying where the definition came from.
   Increasing numeric values signify less-overridable definitions.  */
enum variable_origin
  {
    o_default,		/* Variable from the default set.  */
    o_env,		/* Variable from environment.  */
    o_file,		/* Variable given in a makefile.  */
    o_env_override,	/* Variable from environment, if -e.  */
    o_command,		/* Variable given by user.  */
    o_override, 	/* Variable from an `override' directive.  */
    o_automatic,	/* Automatic variable -- cannot be set.  */
    o_invalid		/* Core dump time.  */
  };

/* Structure that represents one variable definition.
   Each bucket of the hash table is a chain of these,
   chained through `next'.  */

struct variable
  {
    struct variable *next;	/* Link in the chain.  */
    char *name;			/* Variable name.  */
    char *value;		/* Variable value.  */
    enum variable_origin
      origin ENUM_BITFIELD (3);	/* Variable origin.  */
    unsigned int recursive:1;	/* Gets recursively re-evaluated.  */
    unsigned int expanding:1;	/* Nonzero if currently being expanded.  */
    enum
      {
	v_export,		/* Export this variable.  */
	v_noexport,		/* Don't export this variable.  */
	v_ifset,		/* Export it if it has a non-default value.  */
	v_default		/* Decide in target_environment.  */
      } export ENUM_BITFIELD (2);
  };

/* Structure that represents a variable set.  */

struct variable_set
  {
    struct variable **table;	/* Hash table of variables.  */
    unsigned int buckets;	/* Number of hash buckets in `table'.  */
  };

/* Structure that represents a list of variable sets.  */

struct variable_set_list
  {
    struct variable_set_list *next;	/* Link in the chain.  */
    struct variable_set *set;		/* Variable set.  */
  };

extern struct variable_set_list *current_variable_set_list;


extern void push_new_variable_scope (), pop_variable_scope ();

extern int handle_function ();

extern char *variable_buffer_output ();
extern char *variable_expand (), *variable_expand_for_file ();
extern char *allocated_variable_expand_for_file ();
#define	allocated_variable_expand(line) \
  allocated_variable_expand_for_file (line, (struct file *) 0)
extern char *expand_argument ();

extern void define_automatic_variables ();
extern void initialize_file_variables ();
extern void print_file_variables ();

extern void merge_variable_set_lists ();

extern struct variable *try_variable_definition ();

extern struct variable *lookup_variable (), *define_variable ();
extern struct variable *define_variable_for_file ();

extern int pattern_matches ();
extern char *subst_expand (), *patsubst_expand (), *recursively_expand ();

extern char **target_environment ();
extern int export_all_variables;