/* xgettext Scheme backend.
   Copyright (C) 2004-2009, 2011 Free Software Foundation, Inc.

   This file was written by Bruno Haible <bruno@clisp.org>, 2004-2005.

   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/>.  */

#ifdef HAVE_CONFIG_H
# include "config.h"
#endif

/* Specification.  */
#include "x-scheme.h"

#include <errno.h>
#include <stdbool.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>

#include "message.h"
#include "xgettext.h"
#include "error.h"
#include "xalloc.h"
#include "hash.h"
#include "gettext.h"

#define _(s) gettext(s)


/* The Scheme syntax is described in R5RS.  It is implemented in
   guile-2.0.0/libguile/read.c.
   Since we are interested only in strings and in forms similar to
        (gettext msgid ...)
   or   (ngettext msgid msgid_plural ...)
   we make the following simplifications:

   - Assume the keywords and strings are in an ASCII compatible encoding.
     This means we can read the input file one byte at a time, instead of
     one character at a time.  No need to worry about multibyte characters:
     If they occur as part of identifiers, they most probably act as
     constituent characters, and the byte based approach will do the same.

   - Assume the read-hash-procedures is in the default state.
     Non-standard reader extensions are mostly used to read data, not programs.

   The remaining syntax rules are:

   - The syntax code assigned to each character, and how tokens are built
     up from characters (single escape, multiple escape etc.).

   - Comment syntax: ';' and '#! ... !#' and '#| ... |#' (may be nested).

   - String syntax: "..." with single escapes.

   - Read macros and dispatch macro character '#'.  Needed to be able to
     tell which is the n-th argument of a function call.

 */


/* ====================== Keyword set customization.  ====================== */

/* If true extract all strings.  */
static bool extract_all = false;

static hash_table keywords;
static bool default_keywords = true;


void
x_scheme_extract_all ()
{
  extract_all = true;
}


void
x_scheme_keyword (const char *name)
{
  if (name == NULL)
    default_keywords = false;
  else
    {
      const char *end;
      struct callshape shape;
      const char *colon;

      if (keywords.table == NULL)
        hash_init (&keywords, 100);

      split_keywordspec (name, &end, &shape);

      /* The characters between name and end should form a valid Lisp symbol.
         Extract the symbol name part.  */
      colon = strchr (name, ':');
      if (colon != NULL && colon < end)
        {
          name = colon + 1;
          if (name < end && *name == ':')
            name++;
          colon = strchr (name, ':');
          if (colon != NULL && colon < end)
            return;
        }

      insert_keyword_callshape (&keywords, name, end - name, &shape);
    }
}

/* Finish initializing the keywords hash table.
   Called after argument processing, before each file is processed.  */
static void
init_keywords ()
{
  if (default_keywords)
    {
      /* When adding new keywords here, also update the documentation in
         xgettext.texi!  */
      x_scheme_keyword ("gettext");             /* libguile/i18n.c */
      x_scheme_keyword ("ngettext:1,2");        /* libguile/i18n.c */
      x_scheme_keyword ("gettext-noop");
      default_keywords = false;
    }
}

void
init_flag_table_scheme ()
{
  xgettext_record_flag ("gettext:1:pass-scheme-format");
  xgettext_record_flag ("ngettext:1:pass-scheme-format");
  xgettext_record_flag ("ngettext:2:pass-scheme-format");
  xgettext_record_flag ("gettext-noop:1:pass-scheme-format");
  xgettext_record_flag ("format:2:scheme-format");
}


/* ======================== Reading of characters.  ======================== */

/* Real filename, used in error messages about the input file.  */
static const char *real_file_name;

/* Logical filename and line number, used to label the extracted messages.  */
static char *logical_file_name;
static int line_number;

/* The input file stream.  */
static FILE *fp;


/* Fetch the next character from the input file.  */
static int
do_getc ()
{
  int c = getc (fp);

  if (c == EOF)
    {
      if (ferror (fp))
        error (EXIT_FAILURE, errno, _("\
error while reading \"%s\""), real_file_name);
    }
  else if (c == '\n')
   line_number++;

  return c;
}

/* Put back the last fetched character, not EOF.  */
static void
do_ungetc (int c)
{
  if (c == '\n')
    line_number--;
  ungetc (c, fp);
}


/* ========================== Reading of tokens.  ========================== */


/* A token consists of a sequence of characters.  */
struct token
{
  int allocated;                /* number of allocated 'token_char's */
  int charcount;                /* number of used 'token_char's */
  char *chars;                  /* the token's constituents */
};

/* Initialize a 'struct token'.  */
static inline void
init_token (struct token *tp)
{
  tp->allocated = 10;
  tp->chars = XNMALLOC (tp->allocated, char);
  tp->charcount = 0;
}

/* Free the memory pointed to by a 'struct token'.  */
static inline void
free_token (struct token *tp)
{
  free (tp->chars);
}

/* Ensure there is enough room in the token for one more character.  */
static inline void
grow_token (struct token *tp)
{
  if (tp->charcount == tp->allocated)
    {
      tp->allocated *= 2;
      tp->chars = (char *) xrealloc (tp->chars, tp->allocated * sizeof (char));
    }
}

/* Read the next token.  'first' is the first character, which has already
   been read.  */
static void
read_token (struct token *tp, int first)
{
  init_token (tp);

  grow_token (tp);
  tp->chars[tp->charcount++] = first;

  for (;;)
    {
      int c = do_getc ();

      if (c == EOF)
        break;
      if (c == ' ' || c == '\r' || c == '\f' || c == '\t' || c == '\n'
          || c == '"' || c == '(' || c == ')' || c == ';')
        {
          do_ungetc (c);
          break;
        }
      grow_token (tp);
      tp->chars[tp->charcount++] = c;
    }
}

/* Tests if a token represents an integer.
   Taken from guile-1.6.4/libguile/numbers.c:scm_istr2int().  */
static inline bool
is_integer_syntax (const char *str, int len, int radix)
{
  const char *p = str;
  const char *p_end = str + len;

  /* The accepted syntax is
       ['+'|'-'] DIGIT+
     where DIGIT is a hexadecimal digit whose value is below radix.  */

  if (p == p_end)
    return false;
  if (*p == '+' || *p == '-')
    {
      p++;
      if (p == p_end)
        return false;
    }
  do
    {
      int c = *p++;

      if (c >= '0' && c <= '9')
        c = c - '0';
      else if (c >= 'A' && c <= 'F')
        c = c - 'A' + 10;
      else if (c >= 'a' && c <= 'f')
        c = c - 'a' + 10;
      else
        return false;
      if (c >= radix)
        return false;
    }
  while (p < p_end);
  return true;
}

/* Tests if a token represents a rational, floating-point or complex number.
   If unconstrained is false, only real numbers are accepted; otherwise,
   complex numbers are accepted as well.
   Taken from guile-1.6.4/libguile/numbers.c:scm_istr2flo().  */
static inline bool
is_other_number_syntax (const char *str, int len, int radix, bool unconstrained)
{
  const char *p = str;
  const char *p_end = str + len;
  bool seen_sign;
  bool seen_digits;

  /* The accepted syntaxes are:
     for a floating-point number:
       ['+'|'-'] DIGIT+ [EXPONENT]
       ['+'|'-'] DIGIT* '.' DIGIT+ [EXPONENT]
       where EXPONENT ::= ['d'|'e'|'f'|'l'|'s'] DIGIT+
       (Dot and exponent are allowed only if radix is 10.)
     for a rational number:
       ['+'|'-'] DIGIT+ '/' DIGIT+
     for a complex number:
       REAL-NUMBER {'+'|'-'} REAL-NUMBER-WITHOUT-SIGN 'i'
       REAL-NUMBER {'+'|'-'} 'i'
       {'+'|'-'} REAL-NUMBER-WITHOUT-SIGN 'i'
       {'+'|'-'} 'i'
       REAL-NUMBER '@' REAL-NUMBER
   */
  if (p == p_end)
    return false;
  /* Parse leading sign.  */
  seen_sign = false;
  if (*p == '+' || *p == '-')
    {
      p++;
      if (p == p_end)
        return false;
      seen_sign = true;
      /* Recognize complex number syntax: {'+'|'-'} 'i'  */
      if (unconstrained && (*p == 'I' || *p == 'i') && p + 1 == p_end)
        return true;
    }
  /* Parse digits before dot or exponent or slash.  */
  seen_digits = false;
  do
    {
      int c = *p;

      if (c >= '0' && c <= '9')
        c = c - '0';
      else if (c >= 'A' && c <= 'F')
        {
          if (c >= 'D' && radix == 10) /* exponent? */
            break;
          c = c - 'A' + 10;
        }
      else if (c >= 'a' && c <= 'f')
        {
          if (c >= 'd' && radix == 10) /* exponent? */
            break;
          c = c - 'a' + 10;
        }
      else
        break;
      if (c >= radix)
        return false;
      seen_digits = true;
      p++;
    }
  while (p < p_end);
  /* If p == p_end, we know that seen_digits = true, and the number is an
     integer without exponent.  */
  if (p < p_end)
    {
      /* If we have no digits so far, we need a decimal point later.  */
      if (!seen_digits && !(*p == '.' && radix == 10))
        return false;
      /* Trailing '#' signs are equivalent to zeroes.  */
      while (p < p_end && *p == '#')
        p++;
      if (p < p_end)
        {
          if (*p == '/')
            {
              /* Parse digits after the slash.  */
              bool all_zeroes = true;
              p++;
              for (; p < p_end; p++)
                {
                  int c = *p;

                  if (c >= '0' && c <= '9')
                    c = c - '0';
                  else if (c >= 'A' && c <= 'F')
                    c = c - 'A' + 10;
                  else if (c >= 'a' && c <= 'f')
                    c = c - 'a' + 10;
                  else
                    break;
                  if (c >= radix)
                    return false;
                  if (c != 0)
                    all_zeroes = false;
                }
              /* A zero denominator is not allowed.  */
              if (all_zeroes)
                return false;
              /* Trailing '#' signs are equivalent to zeroes.  */
              while (p < p_end && *p == '#')
                p++;
            }
          else
            {
              if (*p == '.')
                {
                  /* Decimal point notation.  */
                  if (radix != 10)
                    return false;
                  /* Parse digits after the decimal point.  */
                  p++;
                  for (; p < p_end; p++)
                    {
                      int c = *p;

                      if (c >= '0' && c <= '9')
                        seen_digits = true;
                      else
                        break;
                    }
                  /* Digits are required before or after the decimal point.  */
                  if (!seen_digits)
                    return false;
                  /* Trailing '#' signs are equivalent to zeroes.  */
                  while (p < p_end && *p == '#')
                    p++;
                }
              if (p < p_end)
                {
                  /* Parse exponent.  */
                  switch (*p)
                    {
                    case 'D': case 'd':
                    case 'E': case 'e':
                    case 'F': case 'f':
                    case 'L': case 'l':
                    case 'S': case 's':
                      if (radix != 10)
                        return false;
                      p++;
                      if (p == p_end)
                        return false;
                      if (*p == '+' || *p == '-')
                        {
                          p++;
                          if (p == p_end)
                            return false;
                        }
                      if (!(*p >= '0' && *p <= '9'))
                        return false;
                      for (;;)
                        {
                          p++;
                          if (p == p_end)
                            break;
                          if (!(*p >= '0' && *p <= '9'))
                            break;
                        }
                      break;
                    default:
                      break;
                    }
                }
            }
        }
    }
  if (p == p_end)
    return true;
  /* Recognize complex number syntax.  */
  if (unconstrained)
    {
      /* Recognize the syntax  {'+'|'-'} REAL-NUMBER-WITHOUT-SIGN 'i'  */
      if (seen_sign && (*p == 'I' || *p == 'i') && p + 1 == p_end)
        return true;
      /* Recognize the syntaxes
           REAL-NUMBER {'+'|'-'} REAL-NUMBER-WITHOUT-SIGN 'i'
           REAL-NUMBER {'+'|'-'} 'i'
       */
      if (*p == '+' || *p == '-')
        return (p_end[-1] == 'I' || p_end[-1] == 'i')
                && (p + 1 == p_end - 1
                    || is_other_number_syntax (p, p_end - 1 - p, radix, false));
      /* Recognize the syntax  REAL-NUMBER '@' REAL-NUMBER  */
      if (*p == '@')
        {
          p++;
          return is_other_number_syntax (p, p_end - p, radix, false);
        }
    }
  return false;
}

/* Tests if a token represents a number.
   Taken from guile-1.6.4/libguile/numbers.c:scm_istring2number().  */
static bool
is_number (const struct token *tp)
{
  const char *str = tp->chars;
  int len = tp->charcount;
  enum { unknown, exact, inexact } exactness = unknown;
  bool seen_radix_prefix = false;
  bool seen_exactness_prefix = false;

  if (len == 1)
    if (*str == '+' || *str == '-')
      return false;
  while (len >= 2 && *str == '#')
    {
      switch (str[1])
        {
        case 'B': case 'b':
          if (seen_radix_prefix)
            return false;
          seen_radix_prefix = true;
          break;
        case 'O': case 'o':
          if (seen_radix_prefix)
            return false;
          seen_radix_prefix = true;
          break;
        case 'D': case 'd':
          if (seen_radix_prefix)
            return false;
          seen_radix_prefix = true;
          break;
        case 'X': case 'x':
          if (seen_radix_prefix)
            return false;
          seen_radix_prefix = true;
          break;
        case 'E': case 'e':
          if (seen_exactness_prefix)
            return false;
          exactness = exact;
          seen_exactness_prefix = true;
          break;
        case 'I': case 'i':
          if (seen_exactness_prefix)
            return false;
          exactness = inexact;
          seen_exactness_prefix = true;
          break;
        default:
          return false;
        }
      str += 2;
      len -= 2;
    }
  if (exactness != inexact)
    {
      /* Try to parse an integer.  */
      if (is_integer_syntax (str, len, 10))
        return true;
      /* FIXME: Other Scheme implementations support exact rational numbers
         or exact complex numbers.  */
    }
  if (exactness != exact)
    {
      /* Try to parse a rational, floating-point or complex number.  */
      if (is_other_number_syntax (str, len, 10, true))
        return true;
    }
  return false;
}


/* ========================= Accumulating comments ========================= */


static char *buffer;
static size_t bufmax;
static size_t buflen;

static inline void
comment_start ()
{
  buflen = 0;
}

static inline void
comment_add (int c)
{
  if (buflen >= bufmax)
    {
      bufmax = 2 * bufmax + 10;
      buffer = xrealloc (buffer, bufmax);
    }
  buffer[buflen++] = c;
}

static inline void
comment_line_end (size_t chars_to_remove)
{
  buflen -= chars_to_remove;
  while (buflen >= 1
         && (buffer[buflen - 1] == ' ' || buffer[buflen - 1] == '\t'))
    --buflen;
  if (chars_to_remove == 0 && buflen >= bufmax)
    {
      bufmax = 2 * bufmax + 10;
      buffer = xrealloc (buffer, bufmax);
    }
  buffer[buflen] = '\0';
  savable_comment_add (buffer);
}


/* These are for tracking whether comments count as immediately before
   keyword.  */
static int last_comment_line;
static int last_non_comment_line;


/* ========================= Accumulating messages ========================= */


static message_list_ty *mlp;


/* ========================== Reading of objects.  ========================= */


/* We are only interested in symbols (e.g. gettext or ngettext) and strings.
   Other objects need not to be represented precisely.  */
enum object_type
{
  t_symbol,     /* symbol */
  t_string,     /* string */
  t_other,      /* other kind of real object */
  t_dot,        /* '.' pseudo object */
  t_close,      /* ')' pseudo object */
  t_eof         /* EOF marker */
};

struct object
{
  enum object_type type;
  struct token *token;          /* for t_symbol and t_string */
  int line_number_at_start;     /* for t_string */
};

/* Free the memory pointed to by a 'struct object'.  */
static inline void
free_object (struct object *op)
{
  if (op->type == t_symbol || op->type == t_string)
    {
      free_token (op->token);
      free (op->token);
    }
}

/* Convert a t_symbol/t_string token to a char*.  */
static char *
string_of_object (const struct object *op)
{
  char *str;
  int n;

  if (!(op->type == t_symbol || op->type == t_string))
    abort ();
  n = op->token->charcount;
  str = XNMALLOC (n + 1, char);
  memcpy (str, op->token->chars, n);
  str[n] = '\0';
  return str;
}

/* Context lookup table.  */
static flag_context_list_table_ty *flag_context_list_table;

/* Read the next object.  */
static void
read_object (struct object *op, flag_context_ty outer_context)
{
  for (;;)
    {
      int c = do_getc ();
      bool seen_underscore_prefix = false;

      switch (c)
        {
        case EOF:
          op->type = t_eof;
          return;

        case ' ': case '\r': case '\f': case '\t':
          continue;

        case '\n':
          /* Comments assumed to be grouped with a message must immediately
             precede it, with no non-whitespace token on a line between
             both.  */
          if (last_non_comment_line > last_comment_line)
            savable_comment_reset ();
          continue;

        case ';':
          {
            bool all_semicolons = true;

            last_comment_line = line_number;
            comment_start ();
            for (;;)
              {
                c = do_getc ();
                if (c == EOF || c == '\n')
                  break;
                if (c != ';')
                  all_semicolons = false;
                if (!all_semicolons)
                  {
                    /* We skip all leading white space, but not EOLs.  */
                    if (!(buflen == 0 && (c == ' ' || c == '\t')))
                      comment_add (c);
                  }
              }
            comment_line_end (0);
            continue;
          }

        case '(':
          {
             int arg = 0;               /* Current argument number.  */
             flag_context_list_iterator_ty context_iter;
            const struct callshapes *shapes = NULL;
            struct arglist_parser *argparser = NULL;

             for (;; arg++)
               {
                struct object inner;
                flag_context_ty inner_context;

                if (arg == 0)
                  inner_context = null_context;
                else
                  inner_context =
                    inherited_context (outer_context,
                                       flag_context_list_iterator_advance (
                                         &context_iter));

                read_object (&inner, inner_context);

                /* Recognize end of list.  */
                if (inner.type == t_close)
                  {
                    op->type = t_other;
                    last_non_comment_line = line_number;
                    if (argparser != NULL)
                      arglist_parser_done (argparser, arg);
                    return;
                  }

                /* Dots are not allowed in every position.
                   But be tolerant.  */

                /* EOF inside list is illegal.
                   But be tolerant.  */
                if (inner.type == t_eof)
                  break;

                if (arg == 0)
                  {
                    /* This is the function position.  */
                    if (inner.type == t_symbol)
                      {
                        char *symbol_name = string_of_object (&inner);
                        void *keyword_value;

                        if (hash_find_entry (&keywords,
                                             symbol_name, strlen (symbol_name),
                                             &keyword_value)
                            == 0)
                          shapes = (const struct callshapes *) keyword_value;

                        argparser = arglist_parser_alloc (mlp, shapes);

                        context_iter =
                          flag_context_list_iterator (
                            flag_context_list_table_lookup (
                              flag_context_list_table,
                              symbol_name, strlen (symbol_name)));

                        free (symbol_name);
                      }
                    else
                      context_iter = null_context_list_iterator;
                  }
                else
                  {
                    /* These are the argument positions.  */
                    if (argparser != NULL && inner.type == t_string)
                      arglist_parser_remember (argparser, arg,
                                               string_of_object (&inner),
                                               inner_context,
                                               logical_file_name,
                                               inner.line_number_at_start,
                                               savable_comment);
                  }

                free_object (&inner);
              }
            if (argparser != NULL)
              arglist_parser_done (argparser, arg);
          }
          op->type = t_other;
          last_non_comment_line = line_number;
          return;

        case ')':
          /* Tell the caller about the end of list.
             Unmatched closing parenthesis is illegal.
             But be tolerant.  */
          op->type = t_close;
          last_non_comment_line = line_number;
          return;

        case ',':
          {
            int c = do_getc ();
            /* The ,@ handling inside lists is wrong anyway, because
               ,@form expands to an unknown number of elements.  */
            if (c != EOF && c != '@')
              do_ungetc (c);
          }
          /*FALLTHROUGH*/
        case '\'':
        case '`':
          {
            struct object inner;

            read_object (&inner, null_context);

            /* Dots and EOF are not allowed here.  But be tolerant.  */

            free_object (&inner);

            op->type = t_other;
            last_non_comment_line = line_number;
            return;
          }

        case '#':
          /* Dispatch macro handling.  */
          {
            c = do_getc ();
            if (c == EOF)
              /* Invalid input.  Be tolerant, no error message.  */
              {
                op->type = t_other;
                return;
              }

            switch (c)
              {
              case '(': /* Vector */
                do_ungetc (c);
                {
                  struct object inner;
                  read_object (&inner, null_context);
                  /* Dots and EOF are not allowed here.
                     But be tolerant.  */
                  free_object (&inner);
                  op->type = t_other;
                  last_non_comment_line = line_number;
                  return;
                }

              case 'T': case 't': /* Boolean true */
              case 'F': case 'f': /* Boolean false */
                op->type = t_other;
                last_non_comment_line = line_number;
                return;

              case 'B': case 'b':
              case 'O': case 'o':
              case 'D': case 'd':
              case 'X': case 'x':
              case 'E': case 'e':
              case 'I': case 'i':
                {
                  struct token token;
                  do_ungetc (c);
                  read_token (&token, '#');
                  if (is_number (&token))
                    {
                      /* A number.  */
                      free_token (&token);
                      op->type = t_other;
                      last_non_comment_line = line_number;
                      return;
                    }
                  else
                    {
                      if (token.charcount == 2
                          && (token.chars[1] == 'e' || token.chars[1] == 'i'))
                        {
                          c = do_getc ();
                          if (c != EOF)
                            do_ungetc (c);
                          if (c == '(')
                            /* Homogenous vector syntax, see arrays.scm.  */
                            case 'a':   /* Vectors of char */
                            case 'c':   /* Vectors of complex */
                          /*case 'e':*/ /* Vectors of long */
                            case 'h':   /* Vectors of short */
                          /*case 'i':*/ /* Vectors of double-float */
                            case 'l':   /* Vectors of long long */
                            case 's':   /* Vectors of single-float */
                            case 'u':   /* Vectors of unsigned long */
                            case 'y':   /* Vectors of byte */
                              {
                                struct object inner;
                                read_object (&inner, null_context);
                                /* Dots and EOF are not allowed here.
                                   But be tolerant.  */
                                free_token (&token);
                                free_object (&inner);
                                op->type = t_other;
                                last_non_comment_line = line_number;
                                return;
                              }
                        }
                      /* Unknown # object.  But be tolerant.  */
                      free_token (&token);
                      op->type = t_other;
                      last_non_comment_line = line_number;
                      return;
                    }
                }

              case '!':
                /* Block comment '#! ... !#'.  See
                   <http://www.gnu.org/software/guile/manual/html_node/Block-Comments.html>.  */
                {
                  int c;

                  comment_start ();
                  c = do_getc ();
                  for (;;)
                    {
                      if (c == EOF)
                        break;
                      if (c == '!')
                        {
                          c = do_getc ();
                          if (c == EOF)
                            break;
                          if (c == '#')
                            {
                              comment_line_end (0);
                              break;
                            }
                          else
                            comment_add ('!');
                        }
                      else
                        {
                          /* We skip all leading white space.  */
                          if (!(buflen == 0 && (c == ' ' || c == '\t')))
                            comment_add (c);
                          if (c == '\n')
                            {
                              comment_line_end (1);
                              comment_start ();
                            }
                          c = do_getc ();
                        }
                    }
                  if (c == EOF)
                    {
                      /* EOF not allowed here.  But be tolerant.  */
                      op->type = t_eof;
                      return;
                    }
                  last_comment_line = line_number;
                  continue;
                }

              case '|':
                /* Block comment '#| ... |#'.  See
                   <http://www.gnu.org/software/guile/manual/html_node/Block-Comments.html>
                   and <http://srfi.schemers.org/srfi-30/srfi-30.html>.  */
                {
                  int depth = 0;
                  int c;

                  comment_start ();
                  c = do_getc ();
                  for (;;)
                    {
                      if (c == EOF)
                        break;
                      if (c == '|')
                        {
                          c = do_getc ();
                          if (c == EOF)
                            break;
                          if (c == '#')
                            {
                              if (depth == 0)
                                {
                                  comment_line_end (0);
                                  break;
                                }
                              depth--;
                              comment_add ('|');
                              comment_add ('#');
                              c = do_getc ();
                            }
                          else
                            comment_add ('|');
                        }
                      else if (c == '#')
                        {
                          c = do_getc ();
                          if (c == EOF)
                            break;
                          comment_add ('#');
                          if (c == '|')
                            {
                              depth++;
                              comment_add ('|');
                              c = do_getc ();
                            }
                        }
                      else
                        {
                          /* We skip all leading white space.  */
                          if (!(buflen == 0 && (c == ' ' || c == '\t')))
                            comment_add (c);
                          if (c == '\n')
                            {
                              comment_line_end (1);
                              comment_start ();
                            }
                          c = do_getc ();
                        }
                    }
                  if (c == EOF)
                    {
                      /* EOF not allowed here.  But be tolerant.  */
                      op->type = t_eof;
                      return;
                    }
                  last_comment_line = line_number;
                  continue;
                }

              case '*':
                /* Bit vector.  */
                {
                  struct token token;
                  read_token (&token, c);
                  /* The token should consists only of '0' and '1', except
                     for the initial '*'.  But be tolerant.  */
                  free_token (&token);
                  op->type = t_other;
                  last_non_comment_line = line_number;
                  return;
                }

              case '{':
                /* Symbol with multiple escapes: #{...}#  */
                {
                  op->token = XMALLOC (struct token);

                  init_token (op->token);

                  for (;;)
                    {
                      c = do_getc ();

                      if (c == EOF)
                        break;
                      if (c == '\\')
                        {
                          c = do_getc ();
                          if (c == EOF)
                            break;
                        }
                      else if (c == '}')
                        {
                          c = do_getc ();
                          if (c == '#')
                            break;
                          if (c != EOF)
                            do_ungetc (c);
                          c = '}';
                        }
                      grow_token (op->token);
                      op->token->chars[op->token->charcount++] = c;
                    }

                  op->type = t_symbol;
                  last_non_comment_line = line_number;
                  return;
                }

              case '\\':
                /* Character.  */
                {
                  struct token token;
                  c = do_getc ();
                  if (c != EOF)
                    {
                      read_token (&token, c);
                      free_token (&token);
                    }
                  op->type = t_other;
                  last_non_comment_line = line_number;
                  return;
                }

              case ':': /* Keyword.  */
              case '&': /* Deprecated keyword, installed in optargs.scm.  */
                {
                  struct token token;
                  read_token (&token, '-');
                  free_token (&token);
                  op->type = t_other;
                  last_non_comment_line = line_number;
                  return;
                }

              /* The following are installed through read-hash-extend.  */

              /* arrays.scm */
              case '0': case '1': case '2': case '3': case '4':
              case '5': case '6': case '7': case '8': case '9':
                /* Multidimensional array syntax: #nx(...) where
                     n ::= DIGIT+
                     x ::= {'a'|'b'|'c'|'e'|'i'|'s'|'u'}
                 */
                do
                  c = do_getc ();
                while (c >= '0' && c <= '9');
                /* c should be one of {'a'|'b'|'c'|'e'|'i'|'s'|'u'}.
                   But be tolerant.  */
                /*FALLTHROUGH*/
              case '\'': /* boot-9.scm */
              case '.': /* boot-9.scm */
              case ',': /* srfi-10.scm */
                {
                  struct object inner;
                  read_object (&inner, null_context);
                  /* Dots and EOF are not allowed here.
                     But be tolerant.  */
                  free_object (&inner);
                  op->type = t_other;
                  last_non_comment_line = line_number;
                  return;
                }

              default:
                /* Unknown.  */
                op->type = t_other;
                last_non_comment_line = line_number;
                return;
              }
            /*NOTREACHED*/
            abort ();
          }

        case '_':
          /* GIMP script-fu extension: '_' before a string literal is
             considered a gettext call on the string.  */
          {
            int c = do_getc ();
            if (c == EOF)
              /* Invalid input.  Be tolerant, no error message.  */
              {
                op->type = t_other;
                return;
              }
            if (c != '"')
              {
                do_ungetc (c);

                /* If '_' is not followed by a string literal,
                   consider it a part of symbol.  */
                op->token = XMALLOC (struct token);
                read_token (op->token, '_');
                op->type = t_symbol;
                last_non_comment_line = line_number;
                return;
              }
            seen_underscore_prefix = true;
          }
          /*FALLTHROUGH*/

        case '"':
          {
            op->token = XMALLOC (struct token);
            init_token (op->token);
            op->line_number_at_start = line_number;
            for (;;)
              {
                int c = do_getc ();
                if (c == EOF)
                  /* Invalid input.  Be tolerant, no error message.  */
                  break;
                if (c == '"')
                  break;
                if (c == '\\')
                  {
                    c = do_getc ();
                    if (c == EOF)
                      /* Invalid input.  Be tolerant, no error message.  */
                      break;
                    switch (c)
                      {
                      case '\n':
                        continue;
                      case '0':
                        c = '\0';
                        break;
                      case 'a':
                        c = '\a';
                        break;
                      case 'f':
                        c = '\f';
                        break;
                      case 'n':
                        c = '\n';
                        break;
                      case 'r':
                        c = '\r';
                        break;
                      case 't':
                        c = '\t';
                        break;
                      case 'v':
                        c = '\v';
                        break;
                      default:
                        break;
                      }
                  }
                grow_token (op->token);
                op->token->chars[op->token->charcount++] = c;
              }
            op->type = t_string;

            if (seen_underscore_prefix || extract_all)
              {
                lex_pos_ty pos;

                pos.file_name = logical_file_name;
                pos.line_number = op->line_number_at_start;
                remember_a_message (mlp, NULL, string_of_object (op),
                                    null_context, &pos, NULL, savable_comment);
              }
            last_non_comment_line = line_number;
            return;
          }

        case '0': case '1': case '2': case '3': case '4':
        case '5': case '6': case '7': case '8': case '9':
        case '+': case '-': case '.':
          /* Read a number or symbol token.  */
          op->token = XMALLOC (struct token);
          read_token (op->token, c);
          if (op->token->charcount == 1 && op->token->chars[0] == '.')
            {
              free_token (op->token);
              free (op->token);
              op->type = t_dot;
            }
          else if (is_number (op->token))
            {
              /* A number.  */
              free_token (op->token);
              free (op->token);
              op->type = t_other;
            }
          else
            {
              /* A symbol.  */
              op->type = t_symbol;
            }
          last_non_comment_line = line_number;
          return;

        case ':':
        default:
          /* Read a symbol token.  */
          op->token = XMALLOC (struct token);
          read_token (op->token, c);
          op->type = t_symbol;
          last_non_comment_line = line_number;
          return;
        }
    }
}


void
extract_scheme (FILE *f,
                const char *real_filename, const char *logical_filename,
                flag_context_list_table_ty *flag_table,
                msgdomain_list_ty *mdlp)
{
  mlp = mdlp->item[0]->messages;

  fp = f;
  real_file_name = real_filename;
  logical_file_name = xstrdup (logical_filename);
  line_number = 1;

  last_comment_line = -1;
  last_non_comment_line = -1;

  flag_context_list_table = flag_table;

  init_keywords ();

  /* Eat tokens until eof is seen.  When read_object returns
     due to an unbalanced closing parenthesis, just restart it.  */
  do
    {
      struct object toplevel_object;

      read_object (&toplevel_object, null_context);

      if (toplevel_object.type == t_eof)
        break;

      free_object (&toplevel_object);
    }
  while (!feof (fp));

  /* Close scanner.  */
  fp = NULL;
  real_file_name = NULL;
  logical_file_name = NULL;
  line_number = 0;
}
