regex.c

正则表达式匹配源码

	case notwordbound:
	  printf ("/notwordbound");
          break;

	case wordbeg:
	  printf ("/wordbeg");
	  break;

	case wordend:
	  printf ("/wordend");

# ifdef emacs
	case before_dot:
	  printf ("/before_dot");
          break;

	case at_dot:
	  printf ("/at_dot");
          break;

	case after_dot:
	  printf ("/after_dot");
          break;

	case syntaxspec:
          printf ("/syntaxspec");
	  mcnt = *p++;
	  printf ("/%d", mcnt);
          break;

	case notsyntaxspec:
          printf ("/notsyntaxspec");
	  mcnt = *p++;
	  printf ("/%d", mcnt);
	  break;
# endif /* emacs */

	case wordchar:
	  printf ("/wordchar");
          break;

	case notwordchar:
	  printf ("/notwordchar");
          break;

	case begbuf:
	  printf ("/begbuf");
          break;

	case endbuf:
	  printf ("/endbuf");
          break;

        default:
          printf ("?%d", *(p-1));
	}

      putchar ('\n');
    }

  printf ("%d:\tend of pattern.\n", p - start);
}


void
print_compiled_pattern (bufp)
    struct re_pattern_buffer *bufp;
{
  unsigned char *buffer = bufp->buffer;

  print_partial_compiled_pattern (buffer, buffer + bufp->used);
  printf ("%ld bytes used/%ld bytes allocated.\n",
	  bufp->used, bufp->allocated);

  if (bufp->fastmap_accurate && bufp->fastmap)
    {
      printf ("fastmap: ");
      print_fastmap (bufp->fastmap);
    }

  printf ("re_nsub: %d\t", bufp->re_nsub);
  printf ("regs_alloc: %d\t", bufp->regs_allocated);
  printf ("can_be_null: %d\t", bufp->can_be_null);
  printf ("newline_anchor: %d\n", bufp->newline_anchor);
  printf ("no_sub: %d\t", bufp->no_sub);
  printf ("not_bol: %d\t", bufp->not_bol);
  printf ("not_eol: %d\t", bufp->not_eol);
  printf ("syntax: %lx\n", bufp->syntax);
  /* Perhaps we should print the translate table?  */
}


void
print_double_string (where, string1, size1, string2, size2)
    const char *where;
    const char *string1;
    const char *string2;
    int size1;
    int size2;
{
  int this_char;

  if (where == NULL)
    printf ("(null)");
  else
    {
      if (FIRST_STRING_P (where))
        {
          for (this_char = where - string1; this_char < size1; this_char++)
            putchar (string1[this_char]);

          where = string2;
        }

      for (this_char = where - string2; this_char < size2; this_char++)
        putchar (string2[this_char]);
    }
}

void
printchar (c)
     int c;
{
  putc (c, stderr);
}

#else /* not DEBUG */

# undef assert
# define assert(e)

# define DEBUG_STATEMENT(e)
# define DEBUG_PRINT1(x)
# define DEBUG_PRINT2(x1, x2)
# define DEBUG_PRINT3(x1, x2, x3)
# define DEBUG_PRINT4(x1, x2, x3, x4)
# define DEBUG_PRINT_COMPILED_PATTERN(p, s, e)
# define DEBUG_PRINT_DOUBLE_STRING(w, s1, sz1, s2, sz2)

#endif /* not DEBUG */

/* Set by `re_set_syntax' to the current regexp syntax to recognize.  Can
   also be assigned to arbitrarily: each pattern buffer stores its own
   syntax, so it can be changed between regex compilations.  */
/* This has no initializer because initialized variables in Emacs
   become read-only after dumping.  */
reg_syntax_t re_syntax_options;


/* Specify the precise syntax of regexps for compilation.  This provides
   for compatibility for various utilities which historically have
   different, incompatible syntaxes.

   The argument SYNTAX is a bit mask comprised of the various bits
   defined in regex.h.  We return the old syntax.  */

reg_syntax_t
re_set_syntax (syntax)
    reg_syntax_t syntax;
{
  reg_syntax_t ret = re_syntax_options;

  re_syntax_options = syntax;
#ifdef DEBUG
  if (syntax & RE_DEBUG)
    debug = 1;
  else if (debug) /* was on but now is not */
    debug = 0;
#endif /* DEBUG */
  return ret;
}
#ifdef _LIBC
weak_alias (__re_set_syntax, re_set_syntax)
#endif

/* This table gives an error message for each of the error codes listed
   in regex.h.  Obviously the order here has to be same as there.
   POSIX doesn't require that we do anything for REG_NOERROR,
   but why not be nice?  */

static const char *re_error_msgid[] =
  {
    gettext_noop ("Success"),	/* REG_NOERROR */
    gettext_noop ("No match"),	/* REG_NOMATCH */
    gettext_noop ("Invalid regular expression"), /* REG_BADPAT */
    gettext_noop ("Invalid collation character"), /* REG_ECOLLATE */
    gettext_noop ("Invalid character class name"), /* REG_ECTYPE */
    gettext_noop ("Trailing backslash"), /* REG_EESCAPE */
    gettext_noop ("Invalid back reference"), /* REG_ESUBREG */
    gettext_noop ("Unmatched [ or [^"),	/* REG_EBRACK */
    gettext_noop ("Unmatched ( or \\("), /* REG_EPAREN */
    gettext_noop ("Unmatched \\{"), /* REG_EBRACE */
    gettext_noop ("Invalid content of \\{\\}"), /* REG_BADBR */
    gettext_noop ("Invalid range end"),	/* REG_ERANGE */
    gettext_noop ("Memory exhausted"), /* REG_ESPACE */
    gettext_noop ("Invalid preceding regular expression"), /* REG_BADRPT */
    gettext_noop ("Premature end of regular expression"), /* REG_EEND */
    gettext_noop ("Regular expression too big"), /* REG_ESIZE */
    gettext_noop ("Unmatched ) or \\)"), /* REG_ERPAREN */
  };

/* Avoiding alloca during matching, to placate r_alloc.  */

/* Define MATCH_MAY_ALLOCATE unless we need to make sure that the
   searching and matching functions should not call alloca.  On some
   systems, alloca is implemented in terms of malloc, and if we're
   using the relocating allocator routines, then malloc could cause a
   relocation, which might (if the strings being searched are in the
   ralloc heap) shift the data out from underneath the regexp
   routines.

   Here's another reason to avoid allocation: Emacs
   processes input from X in a signal handler; processing X input may
   call malloc; if input arrives while a matching routine is calling
   malloc, then we're scrod.  But Emacs can't just block input while
   calling matching routines; then we don't notice interrupts when
   they come in.  So, Emacs blocks input around all regexp calls
   except the matching calls, which it leaves unprotected, in the
   faith that they will not malloc.  */

/* Normally, this is fine.  */
#define MATCH_MAY_ALLOCATE

/* When using GNU C, we are not REALLY using the C alloca, no matter
   what config.h may say.  So don't take precautions for it.  */
#ifdef __GNUC__
# undef C_ALLOCA
#endif

/* The match routines may not allocate if (1) they would do it with malloc
   and (2) it's not safe for them to use malloc.
   Note that if REL_ALLOC is defined, matching would not use malloc for the
   failure stack, but we would still use it for the register vectors;
   so REL_ALLOC should not affect this.  */
#if (defined C_ALLOCA || defined REGEX_MALLOC) && defined emacs
# undef MATCH_MAY_ALLOCATE
#endif


/* Failure stack declarations and macros; both re_compile_fastmap and
   re_match_2 use a failure stack.  These have to be macros because of
   REGEX_ALLOCATE_STACK.  */


/* Number of failure points for which to initially allocate space
   when matching.  If this number is exceeded, we allocate more
   space, so it is not a hard limit.  */
#ifndef INIT_FAILURE_ALLOC
# define INIT_FAILURE_ALLOC 5
#endif

/* Roughly the maximum number of failure points on the stack.  Would be
   exactly that if always used MAX_FAILURE_ITEMS items each time we failed.
   This is a variable only so users of regex can assign to it; we never
   change it ourselves.  */

#ifdef INT_IS_16BIT

# if defined MATCH_MAY_ALLOCATE
/* 4400 was enough to cause a crash on Alpha OSF/1,
   whose default stack limit is 2mb.  */
long int re_max_failures = 4000;
# else
long int re_max_failures = 2000;
# endif

union fail_stack_elt
{
  unsigned char *pointer;
  long int integer;
};

typedef union fail_stack_elt fail_stack_elt_t;

typedef struct
{
  fail_stack_elt_t *stack;
  unsigned long int size;
  unsigned long int avail;		/* Offset of next open position.  */
} fail_stack_type;

#else /* not INT_IS_16BIT */

# if defined MATCH_MAY_ALLOCATE
/* 4400 was enough to cause a crash on Alpha OSF/1,
   whose default stack limit is 2mb.  */
int re_max_failures = 20000;
# else
int re_max_failures = 2000;
# endif

union fail_stack_elt
{
  unsigned char *pointer;
  int integer;
};

typedef union fail_stack_elt fail_stack_elt_t;

typedef struct
{
  fail_stack_elt_t *stack;
  unsigned size;
  unsigned avail;			/* Offset of next open position.  */
} fail_stack_type;

#endif /* INT_IS_16BIT */

#define FAIL_STACK_EMPTY()     (fail_stack.avail == 0)
#define FAIL_STACK_PTR_EMPTY() (fail_stack_ptr->avail == 0)
#define FAIL_STACK_FULL()      (fail_stack.avail == fail_stack.size)


/* Define macros to initialize and free the failure stack.
   Do `return -2' if the alloc fails.  */

#ifdef MATCH_MAY_ALLOCATE
# define INIT_FAIL_STACK()						\
  do {									\
    fail_stack.stack = (fail_stack_elt_t *)				\
      REGEX_ALLOCATE_STACK (INIT_FAILURE_ALLOC * sizeof (fail_stack_elt_t)); \
									\
    if (fail_stack.stack == NULL)					\
      return -2;							\
									\
    fail_stack.size = INIT_FAILURE_ALLOC;				\
    fail_stack.avail = 0;						\
  } while (0)

# define RESET_FAIL_STACK()  REGEX_FREE_STACK (fail_stack.stack)
#else
# define INIT_FAIL_STACK()						\
  do {									\
    fail_stack.avail = 0;						\
  } while (0)

# define RESET_FAIL_STACK()
#endif


/* Double the size of FAIL_STACK, up to approximately `re_max_failures' items.

   Return 1 if succeeds, and 0 if either ran out of memory
   allocating space for it or it was already too large.

   REGEX_REALLOCATE_STACK requires `destination' be declared.   */

#define DOUBLE_FAIL_STACK(fail_stack)					\
  ((fail_stack).size > (unsigned) (re_max_failures * MAX_FAILURE_ITEMS)	\
   ? 0									\
   : ((fail_stack).stack = (fail_stack_elt_t *)				\
        REGEX_REALLOCATE_STACK ((fail_stack).stack, 			\
          (fail_stack).size * sizeof (fail_stack_elt_t),		\
          ((fail_stack).size << 1) * sizeof (fail_stack_elt_t)),	\
									\
      (fail_stack).stack == NULL					\
      ? 0								\
      : ((fail_stack).size <<= 1, 					\
         1)))


/* Push pointer POINTER on FAIL_STACK.
   Return 1 if was able to do so and 0 if ran out of memory allocating
   space to do so.  */
#define PUSH_PATTERN_OP(POINTER, FAIL_STACK)				\
  ((FAIL_STACK_FULL ()							\
    && !DOUBLE_FAIL_STACK (FAIL_STACK))					\
   ? 0									\
   : ((FAIL_STACK).stack[(FAIL_STACK).avail++].pointer = POINTER,	\
      1))

/* Push a pointer value onto the failure stack.
   Assumes the variable `fail_stack'.  Probably should only
   be called from within `PUSH_FAILURE_POINT'.  */
#define PUSH_FAILURE_POINTER(item)					\
  fail_stack.stack[fail_stack.avail++].pointer = (unsigned char *) (item)

/* This pushes an integer-valued item onto the failure stack.
   Assumes the variable `fail_stack'.  Probably should only
   be called from within `PUSH_FAILURE_POINT'.  */
#define PUSH_FAILURE_INT(item)					\
  fail_stack.stack[fail_stack.avail++].integer = (item)

/* Push a fail_stack_elt_t value onto the failure stack.
   Assumes the variable `fail_stack'.  Probably should only
   be called from within `PUSH_FAILURE_POINT'.  */
#define PUSH_FAILURE_ELT(item)					\
  fail_stack.stack[fail_stack.avail++] =  (item)

/* These three POP... operations complement the three PUSH... operations.
   All assume that `fail_stack' is nonempty.  */
#define POP_FAILURE_POINTER() fail_stack.stack[--fail_stack.avail].pointer
#define POP_FAILURE_INT() fail_stack.stack[--fail_stack.avail].integer
#define POP_FAILURE_ELT() fail_stack.stack[--fail_stack.avail]

/* Used to omit pushing failure point id's when we're not debugging.  */
#ifdef DEBUG
# define DEBUG_PUSH PUSH_FAILURE_INT
# define DEBUG_POP(item_addr) *(item_addr) = POP_FAILURE_INT ()
#else
# define DEBUG_PUSH(item)
# define DEBUG_POP(item_addr)
#endif


/* Push the information about the state we will need
   if we ever fail back to it.

   Requires variables fail_stack, regstart, regend, reg_info, and
   num_regs_pushed be declared.  DOUBLE_FAIL_STACK requires `destination'
   be declared.