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[make.git] / expand.c

/* Variable expansion functions for GNU Make.
Copyright (C) 1988, 89, 91, 92, 93, 95 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.  */

#include "make.h"
#include "commands.h"
#include "file.h"
#include "variable.h"

/* The next two describe the variable output buffer.
   This buffer is used to hold the variable-expansion of a line of the
   makefile.  It is made bigger with realloc whenever it is too small.
   variable_buffer_length is the size currently allocated.
   variable_buffer is the address of the buffer.  */

static unsigned int variable_buffer_length;
static char *variable_buffer;

/* Subroutine of variable_expand and friends:
   The text to add is LENGTH chars starting at STRING to the variable_buffer.
   The text is added to the buffer at PTR, and the updated pointer into
   the buffer is returned as the value.  Thus, the value returned by
   each call to variable_buffer_output should be the first argument to
   the following call.  */

char *
variable_buffer_output (ptr, string, length)
     char *ptr, *string;
     unsigned int length;
{
  register unsigned int newlen = length + (ptr - variable_buffer);

  if (newlen > variable_buffer_length)
    {
      unsigned int offset = ptr - variable_buffer;
      variable_buffer_length = (newlen + 100 > 2 * variable_buffer_length
                                ? newlen + 100
                                : 2 * variable_buffer_length);
      variable_buffer = (char *) xrealloc (variable_buffer,
                                           variable_buffer_length);
      ptr = variable_buffer + offset;
    }

  bcopy (string, ptr, length);
  return ptr + length;
}

/* Return a pointer to the beginning of the variable buffer.  */

static char *
initialize_variable_output ()
{
  /* If we don't have a variable output buffer yet, get one.  */

  if (variable_buffer == 0)
    {
      variable_buffer_length = 200;
      variable_buffer = (char *) xmalloc (variable_buffer_length);
      variable_buffer[0] = '\0';
    }

  return variable_buffer;
}
\f
/* Recursively expand V.  The returned string is malloc'd.  */

char *
recursively_expand (v)
     register struct variable *v;
{
  char *value;

  if (v->expanding)
    {
      /* Expanding V causes infinite recursion.  Lose.  */
      if (reading_filename == 0)
        fatal ("Recursive variable `%s' references itself (eventually)",
               v->name);
      else
        makefile_fatal
          (reading_filename, *reading_lineno_ptr, 
           "Recursive variable `%s' references itself (eventually)",
           v->name);
    }

  v->expanding = 1;
  value = allocated_variable_expand (v->value);
  v->expanding = 0;

  return value;
}

/* Warn that NAME is an undefined variable.  */

#ifdef __GNUC__
__inline
#endif
static void
warn_undefined (name, length)
     char *name;
     unsigned int length;
{
  if (warn_undefined_variables_flag)
    {
      static const char warnmsg[] = "warning: undefined variable `%.*s'";
      if (reading_filename != 0)
        makefile_error (reading_filename, *reading_lineno_ptr,
                        warnmsg, length, name);
      else
        error (warnmsg, length, name);
    }
}

/* Expand a simple reference to variable NAME, which is LENGTH chars long.  */

#ifdef __GNUC__
__inline
#endif
static char *
reference_variable (o, name, length)
     char *o;
     char *name;
     unsigned int length;
{
  register struct variable *v = lookup_variable (name, length);

  if (v == 0)
    warn_undefined (name, length);

  if (v != 0 && *v->value != '\0')
    {
      char *value = (v->recursive ? recursively_expand (v) : v->value);
      o = variable_buffer_output (o, value, strlen (value));
      if (v->recursive)
        free (value);
    }

  return o;
}
\f
/* Scan LINE for variable references and expansion-function calls.
   Build in `variable_buffer' the result of expanding the references and calls.
   Return the address of the resulting string, which is null-terminated
   and is valid only until the next time this function is called.  */

char *
variable_expand (line)
     register char *line;
{
  register struct variable *v;
  register char *p, *o, *p1;

  p = line;
  o = initialize_variable_output ();

  while (1)
    {
      /* Copy all following uninteresting chars all at once to the
         variable output buffer, and skip them.  Uninteresting chars end
         at the next $ or the end of the input.  */

      p1 = index (p, '$');

      o = variable_buffer_output (o, p, p1 != 0 ? p1 - p : strlen (p) + 1);

      if (p1 == 0)
        break;
      p = p1 + 1;

      /* Dispatch on the char that follows the $.  */

      switch (*p)
        {
        case '$':
          /* $$ seen means output one $ to the variable output buffer.  */
          o = variable_buffer_output (o, p, 1);
          break;

        case '(':
        case '{':
          /* $(...) or ${...} is the general case of substitution.  */
          {
            char openparen = *p;
            char closeparen = (openparen == '(') ? ')' : '}';
            register char *beg = p + 1;
            int free_beg = 0;
            char *op, *begp;
            char *end, *colon;

            op = o;
            begp = p;
            if (handle_function (&op, &begp))
              {
                o = op;
                p = begp;
                break;
              }

            /* Is there a variable reference inside the parens or braces?
               If so, expand it before expanding the entire reference.  */

            end = index (beg, closeparen);
            if (end == 0)
              {
                /* Unterminated variable reference.  */
                if (reading_filename != 0)
                  makefile_fatal (reading_filename, *reading_lineno_ptr,
                                  "unterminated variable reference");
                else
                  fatal ("unterminated variable reference");
              }
            p1 = lindex (beg, end, '$');
            if (p1 != 0)
              {
                /* BEG now points past the opening paren or brace.
                   Count parens or braces until it is matched.  */
                int count = 0;
                for (p = beg; *p != '\0'; ++p)
                  {
                    if (*p == openparen)
                      ++count;
                    else if (*p == closeparen && --count < 0)
                      break;
                  }
                /* If COUNT is >= 0, there were unmatched opening parens
                   or braces, so we go to the simple case of a variable name
                   such as `$($(a)'.  */
                if (count < 0)
                  {
                    beg = expand_argument (beg, p); /* Expand the name.  */
                    free_beg = 1; /* Remember to free BEG when finished.  */
                    end = index (beg, '\0');
                  }
              }
            else
              /* Advance P to the end of this reference.  After we are
                 finished expanding this one, P will be incremented to
                 continue the scan.  */
              p = end;

            /* This is not a reference to a built-in function and
               any variable references inside are now expanded.
               Is the resultant text a substitution reference?  */

            colon = lindex (beg, end, ':');
            if (colon != 0)
              {
                /* This looks like a substitution reference: $(FOO:A=B).  */
                char *subst_beg, *subst_end, *replace_beg, *replace_end;

                subst_beg = colon + 1;
                subst_end = index (subst_beg, '=');
                if (subst_end == 0)
                  /* There is no = in sight.  Punt on the substitution
                     reference and treat this as a variable name containing
                     a colon, in the code below.  */
                  colon = 0;
                else
                  {
                    replace_beg = subst_end + 1;
                    replace_end = end;

                    /* Extract the variable name before the colon
                       and look up that variable.  */
                    v = lookup_variable (beg, colon - beg);
                    if (v == 0)
                      warn_undefined (beg, colon - beg);

                    if (v != 0 && *v->value != '\0')
                      {
                        char *value = (v->recursive ? recursively_expand (v)
                                       : v->value);
                        char *pattern, *percent;
                        if (free_beg)
                          {
                            *subst_end = '\0';
                            pattern = subst_beg;
                          }
                        else
                          {
                            pattern = (char *) alloca (subst_end - subst_beg
                                                       + 1);
                            bcopy (subst_beg, pattern, subst_end - subst_beg);
                            pattern[subst_end - subst_beg] = '\0';
                          }
                        percent = find_percent (pattern);
                        if (percent != 0)
                          {
                            char *replace;
                            if (free_beg)
                              {
                                *replace_end = '\0';
                                replace = replace_beg;
                              }
                            else
                              {
                                replace = (char *) alloca (replace_end
                                                           - replace_beg
                                                           + 1);
                                bcopy (replace_beg, replace,
                                       replace_end - replace_beg);
                                replace[replace_end - replace_beg] = '\0';
                              }
                            
                            o = patsubst_expand (o, value, pattern, replace,
                                                 percent, (char *) 0);
                          }
                        else
                          o = subst_expand (o, value,
                                            pattern, replace_beg,
                                            strlen (pattern),
                                            end - replace_beg,
                                            0, 1);
                        if (v->recursive)
                          free (value);
                      }
                  }
              }

            if (colon == 0)
              /* This is an ordinary variable reference.
                 Look up the value of the variable.  */
                o = reference_variable (o, beg, end - beg);

          if (free_beg)
            free (beg);
          }
          break;

        case '\0':
          break;

        default:
          if (isblank (p[-1]))
            break;

          /* A $ followed by a random char is a variable reference:
             $a is equivalent to $(a).  */
          {
            /* We could do the expanding here, but this way
               avoids code repetition at a small performance cost.  */
            char name[5];
            name[0] = '$';
            name[1] = '(';
            name[2] = *p;
            name[3] = ')';
            name[4] = '\0';
            p1 = allocated_variable_expand (name);
            o = variable_buffer_output (o, p1, strlen (p1));
            free (p1);
          }

          break;
        }      

      if (*p == '\0')
        break;
      else
        ++p;
    }

  (void) variable_buffer_output (o, "", 1);
  return initialize_variable_output ();
}
\f
/* Expand an argument for an expansion function.
   The text starting at STR and ending at END is variable-expanded
   into a null-terminated string that is returned as the value.
   This is done without clobbering `variable_buffer' or the current
   variable-expansion that is in progress.  */

char *
expand_argument (str, end)
     char *str, *end;
{
  char *tmp;

  if (*end == '\0')
    tmp = str;
  else
    {
      tmp = (char *) alloca (end - str + 1);
      bcopy (str, tmp, end - str);
      tmp[end - str] = '\0';
    }

  return allocated_variable_expand (tmp);
}
\f
/* Expand LINE for FILE.  Error messages refer to the file and line where
   FILE's commands were found.  Expansion uses FILE's variable set list.  */

char *
variable_expand_for_file (line, file)
     char *line;
     register struct file *file;
{
  char *result;
  struct variable_set_list *save;

  if (file == 0)
    return variable_expand (line);

  save = current_variable_set_list;
  current_variable_set_list = file->variables;
  reading_filename = file->cmds->filename;
  reading_lineno_ptr = &file->cmds->lineno;
  result = variable_expand (line);
  current_variable_set_list = save;
  reading_filename = 0;
  reading_lineno_ptr = 0;

  return result;
}
\f
/* Like variable_expand_for_file, but the returned string is malloc'd.
   This function is called a lot.  It wants to be efficient.  */

char *
allocated_variable_expand_for_file (line, file)
     char *line;
     struct file *file;
{
  char *value;

  char *obuf = variable_buffer;
  unsigned int olen = variable_buffer_length;

  variable_buffer = 0;

  value = variable_expand_for_file (line, file);

#if 0
  /* Waste a little memory and save time.  */
  value = xrealloc (value, strlen (value))
#endif

  variable_buffer = obuf;
  variable_buffer_length = olen;

  return value;
}