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cpython/Modules/regexpr.c

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/* regexpr.c
*
* Author: Tatu Ylonen <ylo@ngs.fi>
*
* Copyright (c) 1991 Tatu Ylonen, Espoo, Finland
*
* Permission to use, copy, modify, distribute, and sell this software
* and its documentation for any purpose is hereby granted without
* fee, provided that the above copyright notice appear in all copies.
* This software is provided "as is" without express or implied
* warranty.
*
* Created: Thu Sep 26 17:14:05 1991 ylo
* Last modified: Mon Nov 4 17:06:48 1991 ylo
* Ported to Think C: 19 Jan 1992 guido@cwi.nl
*
* This code draws many ideas from the regular expression packages by
* Henry Spencer of the University of Toronto and Richard Stallman of
* the Free Software Foundation.
*
* Emacs-specific code and syntax table code is almost directly borrowed
* from GNU regexp.
*
* Bugs fixed and lots of reorganization by Jeffrey C. Ollie, April
* 1997 Thanks for bug reports and ideas from Andrew Kuchling, Tim
* Peters, Guido van Rossum, Ka-Ping Yee, Sjoerd Mullender, and
* probably one or two others that I'm forgetting.
*
* $Id$ */
#include "Python.h"
#include "regexpr.h"
/* The original code blithely assumed that sizeof(short) == 2. Not
* always true. Original instances of "(short)x" were replaced by
* SHORT(x), where SHORT is #defined below. */
#define SHORT(x) ((x) & 0x8000 ? (x) - 0x10000 : (x))
/* The stack implementation is taken from an idea by Andrew Kuchling.
* It's a doubly linked list of arrays. The advantages of this over a
* simple linked list are that the number of mallocs required are
* reduced. It also makes it possible to statically allocate enough
* space so that small patterns don't ever need to call malloc.
*
* The advantages over a single array is that is periodically
* realloced when more space is needed is that we avoid ever copying
* the stack. */
/* item_t is the basic stack element. Defined as a union of
* structures so that both registers, failure points, and counters can
* be pushed/popped from the stack. There's nothing built into the
* item to keep track of whether a certain stack item is a register, a
* failure point, or a counter. */
typedef union item_t
{
struct
{
int num;
int level;
unsigned char *start;
unsigned char *end;
} reg;
struct
{
int count;
int level;
int phantom;
unsigned char *code;
unsigned char *text;
} fail;
struct
{
int num;
int level;
int count;
} cntr;
} item_t;
#define STACK_PAGE_SIZE 256
#define NUM_REGISTERS 256
/* A 'page' of stack items. */
typedef struct item_page_t
{
item_t items[STACK_PAGE_SIZE];
struct item_page_t *prev;
struct item_page_t *next;
} item_page_t;
typedef struct match_state
{
/* The number of registers that have been pushed onto the stack
* since the last failure point. */
int count;
/* Used to control when registers need to be pushed onto the
* stack. */
int level;
/* The number of failure points on the stack. */
int point;
/* Storage for the registers. Each register consists of two
* pointers to characters. So register N is represented as
* start[N] and end[N]. The pointers must be converted to
* offsets from the beginning of the string before returning the
* registers to the calling program. */
unsigned char *start[NUM_REGISTERS];
unsigned char *end[NUM_REGISTERS];
/* Keeps track of whether a register has changed recently. */
int changed[NUM_REGISTERS];
/* Structure to encapsulate the stack. */
struct
{
/* index into the current page. If index == 0 and you need
* to pop an item, move to the previous page and set index
* = STACK_PAGE_SIZE - 1. Otherwise decrement index to
* push a page. If index == STACK_PAGE_SIZE and you need
* to push a page move to the next page and set index =
* 0. If there is no new next page, allocate a new page
* and link it in. Otherwise, increment index to push a
* page. */
int index;
item_page_t *current; /* Pointer to the current page. */
item_page_t first; /* First page is statically allocated. */
} stack;
} match_state;
/* Initialize a state object */
/* #define NEW_STATE(state) \ */
/* memset(&state, 0, (void *)(&state.stack) - (void *)(&state)); \ */
/* state.stack.current = &state.stack.first; \ */
/* state.stack.first.prev = NULL; \ */
/* state.stack.first.next = NULL; \ */
/* state.stack.index = 0; \ */
/* state.level = 1 */
#define NEW_STATE(state, nregs) \
{ \
int i; \
for (i = 0; i < nregs; i++) \
{ \
state.start[i] = NULL; \
state.end[i] = NULL; \
state.changed[i] = 0; \
} \
state.stack.current = &state.stack.first; \
state.stack.first.prev = NULL; \
state.stack.first.next = NULL; \
state.stack.index = 0; \
state.level = 1; \
state.count = 0; \
state.level = 0; \
state.point = 0; \
}
/* Free any memory that might have been malloc'd */
#define FREE_STATE(state) \
while(state.stack.first.next != NULL) \
{ \
state.stack.current = state.stack.first.next; \
state.stack.first.next = state.stack.current->next; \
free(state.stack.current); \
}
/* Discard the top 'count' stack items. */
#define STACK_DISCARD(stack, count, on_error) \
stack.index -= count; \
while (stack.index < 0) \
{ \
if (stack.current->prev == NULL) \
on_error; \
stack.current = stack.current->prev; \
stack.index += STACK_PAGE_SIZE; \
}
/* Store a pointer to the previous item on the stack. Used to pop an
* item off of the stack. */
#define STACK_PREV(stack, top, on_error) \
if (stack.index == 0) \
{ \
if (stack.current->prev == NULL) \
on_error; \
stack.current = stack.current->prev; \
stack.index = STACK_PAGE_SIZE - 1; \
} \
else \
{ \
stack.index--; \
} \
top = &(stack.current->items[stack.index])
/* Store a pointer to the next item on the stack. Used to push an item
* on to the stack. */
#define STACK_NEXT(stack, top, on_error) \
if (stack.index == STACK_PAGE_SIZE) \
{ \
if (stack.current->next == NULL) \
{ \
stack.current->next = (item_page_t *)malloc(sizeof(item_page_t)); \
if (stack.current->next == NULL) \
on_error; \
stack.current->next->prev = stack.current; \
stack.current->next->next = NULL; \
} \
stack.current = stack.current->next; \
stack.index = 0; \
} \
top = &(stack.current->items[stack.index++])
/* Store a pointer to the item that is 'count' items back in the
* stack. STACK_BACK(stack, top, 1, on_error) is equivalent to
* STACK_TOP(stack, top, on_error). */
#define STACK_BACK(stack, top, count, on_error) \
{ \
int index; \
item_page_t *current; \
current = stack.current; \
index = stack.index - (count); \
while (index < 0) \
{ \
if (current->prev == NULL) \
on_error; \
current = current->prev; \
index += STACK_PAGE_SIZE; \
} \
top = &(current->items[index]); \
}
/* Store a pointer to the top item on the stack. Execute the
* 'on_error' code if there are no items on the stack. */
#define STACK_TOP(stack, top, on_error) \
if (stack.index == 0) \
{ \
if (stack.current->prev == NULL) \
on_error; \
top = &(stack.current->prev->items[STACK_PAGE_SIZE - 1]); \
} \
else \
{ \
top = &(stack.current->items[stack.index - 1]); \
}
/* Test to see if the stack is empty */
#define STACK_EMPTY(stack) ((stack.index == 0) && \
(stack.current->prev == NULL))
/* Return the start of register 'reg' */
#define GET_REG_START(state, reg) (state.start[reg])
/* Return the end of register 'reg' */
#define GET_REG_END(state, reg) (state.end[reg])
/* Set the start of register 'reg'. If the state of the register needs
* saving, push it on the stack. */
#define SET_REG_START(state, reg, text, on_error) \
if(state.changed[reg] < state.level) \
{ \
item_t *item; \
STACK_NEXT(state.stack, item, on_error); \
item->reg.num = reg; \
item->reg.start = state.start[reg]; \
item->reg.end = state.end[reg]; \
item->reg.level = state.changed[reg]; \
state.changed[reg] = state.level; \
state.count++; \
} \
state.start[reg] = text
/* Set the end of register 'reg'. If the state of the register needs
* saving, push it on the stack. */
#define SET_REG_END(state, reg, text, on_error) \
if(state.changed[reg] < state.level) \
{ \
item_t *item; \
STACK_NEXT(state.stack, item, on_error); \
item->reg.num = reg; \
item->reg.start = state.start[reg]; \
item->reg.end = state.end[reg]; \
item->reg.level = state.changed[reg]; \
state.changed[reg] = state.level; \
state.count++; \
} \
state.end[reg] = text
#define PUSH_FAILURE(state, xcode, xtext, on_error) \
{ \
item_t *item; \
STACK_NEXT(state.stack, item, on_error); \
item->fail.code = xcode; \
item->fail.text = xtext; \
item->fail.count = state.count; \
item->fail.level = state.level; \
item->fail.phantom = 0; \
state.count = 0; \
state.level++; \
state.point++; \
}
/* Update the last failure point with a new position in the text. */
#define UPDATE_FAILURE(state, xtext, on_error) \
{ \
item_t *item; \
STACK_BACK(state.stack, item, state.count + 1, on_error); \
if (!item->fail.phantom) \
{ \
item_t *item2; \
STACK_NEXT(state.stack, item2, on_error); \
item2->fail.code = item->fail.code; \
item2->fail.text = xtext; \
item2->fail.count = state.count; \
item2->fail.level = state.level; \
item2->fail.phantom = 1; \
state.count = 0; \
state.level++; \
state.point++; \
} \
else \
{ \
STACK_DISCARD(state.stack, state.count, on_error); \
STACK_TOP(state.stack, item, on_error); \
item->fail.text = xtext; \
state.count = 0; \
state.level++; \
} \
}
#define POP_FAILURE(state, xcode, xtext, on_empty, on_error) \
{ \
item_t *item; \
do \
{ \
while(state.count > 0) \
{ \
STACK_PREV(state.stack, item, on_error); \
state.start[item->reg.num] = item->reg.start; \
state.end[item->reg.num] = item->reg.end; \
state.changed[item->reg.num] = item->reg.level; \
state.count--; \
} \
STACK_PREV(state.stack, item, on_empty); \
xcode = item->fail.code; \
xtext = item->fail.text; \
state.count = item->fail.count; \
state.level = item->fail.level; \
state.point--; \
} \
while (item->fail.text == NULL); \
}
enum regexp_compiled_ops /* opcodes for compiled regexp */
{
Cend, /* end of pattern reached */
Cbol, /* beginning of line */
Ceol, /* end of line */
Cset, /* character set. Followed by 32 bytes of set. */
Cexact, /* followed by a byte to match */
Canychar, /* matches any character except newline */
Cstart_memory, /* set register start addr (followed by reg number) */
Cend_memory, /* set register end addr (followed by reg number) */
Cmatch_memory, /* match a duplicate of reg contents (regnum follows)*/
Cjump, /* followed by two bytes (lsb,msb) of displacement. */
Cstar_jump, /* will change to jump/update_failure_jump at runtime */
Cfailure_jump, /* jump to addr on failure */
Cupdate_failure_jump, /* update topmost failure point and jump */
Cdummy_failure_jump, /* push a dummy failure point and jump */
Cbegbuf, /* match at beginning of buffer */
Cendbuf, /* match at end of buffer */
Cwordbeg, /* match at beginning of word */
Cwordend, /* match at end of word */
Cwordbound, /* match if at word boundary */
Cnotwordbound, /* match if not at word boundary */
Csyntaxspec, /* matches syntax code (1 byte follows) */
Cnotsyntaxspec, /* matches if syntax code does not match (1 byte follows) */
Crepeat1
};
enum regexp_syntax_op /* syntax codes for plain and quoted characters */
{
Rend, /* special code for end of regexp */
Rnormal, /* normal character */
Ranychar, /* any character except newline */
Rquote, /* the quote character */
Rbol, /* match beginning of line */
Reol, /* match end of line */
Roptional, /* match preceding expression optionally */
Rstar, /* match preceding expr zero or more times */
Rplus, /* match preceding expr one or more times */
Ror, /* match either of alternatives */
Ropenpar, /* opening parenthesis */
Rclosepar, /* closing parenthesis */
Rmemory, /* match memory register */
Rextended_memory, /* \vnn to match registers 10-99 */
Ropenset, /* open set. Internal syntax hard-coded below. */
/* the following are gnu extensions to "normal" regexp syntax */
Rbegbuf, /* beginning of buffer */
Rendbuf, /* end of buffer */
Rwordchar, /* word character */
Rnotwordchar, /* not word character */
Rwordbeg, /* beginning of word */
Rwordend, /* end of word */
Rwordbound, /* word bound */
Rnotwordbound, /* not word bound */
Rnum_ops
};
static int re_compile_initialized = 0;
static int regexp_syntax = 0;
int re_syntax = 0; /* Exported copy of regexp_syntax */
static unsigned char regexp_plain_ops[256];
static unsigned char regexp_quoted_ops[256];
static unsigned char regexp_precedences[Rnum_ops];
static int regexp_context_indep_ops;
static int regexp_ansi_sequences;
#define NUM_LEVELS 5 /* number of precedence levels in use */
#define MAX_NESTING 100 /* max nesting level of operators */
#define SYNTAX(ch) re_syntax_table[(unsigned char)(ch)]
unsigned char re_syntax_table[256];
void re_compile_initialize(void)
{
int a;
static int syntax_table_inited = 0;
if (!syntax_table_inited)
{
syntax_table_inited = 1;
memset(re_syntax_table, 0, 256);
for (a = 'a'; a <= 'z'; a++)
re_syntax_table[a] = Sword;
for (a = 'A'; a <= 'Z'; a++)
re_syntax_table[a] = Sword;
for (a = '0'; a <= '9'; a++)
re_syntax_table[a] = Sword | Sdigit | Shexdigit;
for (a = '0'; a <= '7'; a++)
re_syntax_table[a] |= Soctaldigit;
for (a = 'A'; a <= 'F'; a++)
re_syntax_table[a] |= Shexdigit;
for (a = 'a'; a <= 'f'; a++)
re_syntax_table[a] |= Shexdigit;
re_syntax_table['_'] = Sword;
for (a = 9; a <= 13; a++)
re_syntax_table[a] = Swhitespace;
re_syntax_table[' '] = Swhitespace;
}
re_compile_initialized = 1;
for (a = 0; a < 256; a++)
{
regexp_plain_ops[a] = Rnormal;
regexp_quoted_ops[a] = Rnormal;
}
for (a = '0'; a <= '9'; a++)
regexp_quoted_ops[a] = Rmemory;
regexp_plain_ops['\134'] = Rquote;
if (regexp_syntax & RE_NO_BK_PARENS)
{
regexp_plain_ops['('] = Ropenpar;
regexp_plain_ops[')'] = Rclosepar;
}
else
{
regexp_quoted_ops['('] = Ropenpar;
regexp_quoted_ops[')'] = Rclosepar;
}
if (regexp_syntax & RE_NO_BK_VBAR)
regexp_plain_ops['\174'] = Ror;
else
regexp_quoted_ops['\174'] = Ror;
regexp_plain_ops['*'] = Rstar;
if (regexp_syntax & RE_BK_PLUS_QM)
{
regexp_quoted_ops['+'] = Rplus;
regexp_quoted_ops['?'] = Roptional;
}
else
{
regexp_plain_ops['+'] = Rplus;
regexp_plain_ops['?'] = Roptional;
}
if (regexp_syntax & RE_NEWLINE_OR)
regexp_plain_ops['\n'] = Ror;
regexp_plain_ops['\133'] = Ropenset;
regexp_plain_ops['\136'] = Rbol;
regexp_plain_ops['$'] = Reol;
regexp_plain_ops['.'] = Ranychar;
if (!(regexp_syntax & RE_NO_GNU_EXTENSIONS))
{
regexp_quoted_ops['w'] = Rwordchar;
regexp_quoted_ops['W'] = Rnotwordchar;
regexp_quoted_ops['<'] = Rwordbeg;
regexp_quoted_ops['>'] = Rwordend;
regexp_quoted_ops['b'] = Rwordbound;
regexp_quoted_ops['B'] = Rnotwordbound;
regexp_quoted_ops['`'] = Rbegbuf;
regexp_quoted_ops['\''] = Rendbuf;
}
if (regexp_syntax & RE_ANSI_HEX)
regexp_quoted_ops['v'] = Rextended_memory;
for (a = 0; a < Rnum_ops; a++)
regexp_precedences[a] = 4;
if (regexp_syntax & RE_TIGHT_VBAR)
{
regexp_precedences[Ror] = 3;
regexp_precedences[Rbol] = 2;
regexp_precedences[Reol] = 2;
}
else
{
regexp_precedences[Ror] = 2;
regexp_precedences[Rbol] = 3;
regexp_precedences[Reol] = 3;
}
regexp_precedences[Rclosepar] = 1;
regexp_precedences[Rend] = 0;
regexp_context_indep_ops = (regexp_syntax & RE_CONTEXT_INDEP_OPS) != 0;
regexp_ansi_sequences = (regexp_syntax & RE_ANSI_HEX) != 0;
}
int re_set_syntax(int syntax)
{
int ret;
ret = regexp_syntax;
regexp_syntax = syntax;
re_syntax = syntax; /* Exported copy */
re_compile_initialize();
return ret;
}
static int hex_char_to_decimal(int ch)
{
if (ch >= '0' && ch <= '9')
return ch - '0';
if (ch >= 'a' && ch <= 'f')
return ch - 'a' + 10;
if (ch >= 'A' && ch <= 'F')
return ch - 'A' + 10;
return 16;
}
static void re_compile_fastmap_aux(unsigned char *code, int pos,
unsigned char *visited,
unsigned char *can_be_null,
unsigned char *fastmap)
{
int a;
int b;
int syntaxcode;
if (visited[pos])
return; /* we have already been here */
visited[pos] = 1;
for (;;)
switch (code[pos++]) {
case Cend:
{
*can_be_null = 1;
return;
}
case Cbol:
case Cbegbuf:
case Cendbuf:
case Cwordbeg:
case Cwordend:
case Cwordbound:
case Cnotwordbound:
{
for (a = 0; a < 256; a++)
fastmap[a] = 1;
break;
}
case Csyntaxspec:
{
syntaxcode = code[pos++];
for (a = 0; a < 256; a++)
if (SYNTAX(a) & syntaxcode)
fastmap[a] = 1;
return;
}
case Cnotsyntaxspec:
{
syntaxcode = code[pos++];
for (a = 0; a < 256; a++)
if (!(SYNTAX(a) & syntaxcode) )
fastmap[a] = 1;
return;
}
case Ceol:
{
fastmap['\n'] = 1;
if (*can_be_null == 0)
*can_be_null = 2; /* can match null, but only at end of buffer*/
return;
}
case Cset:
{
for (a = 0; a < 256/8; a++)
if (code[pos + a] != 0)
for (b = 0; b < 8; b++)
if (code[pos + a] & (1 << b))
fastmap[(a << 3) + b] = 1;
pos += 256/8;
return;
}
case Cexact:
{
fastmap[(unsigned char)code[pos]] = 1;
return;
}
case Canychar:
{
for (a = 0; a < 256; a++)
if (a != '\n')
fastmap[a] = 1;
return;
}
case Cstart_memory:
case Cend_memory:
{
pos++;
break;
}
case Cmatch_memory:
{
for (a = 0; a < 256; a++)
fastmap[a] = 1;
*can_be_null = 1;
return;
}
case Cjump:
case Cdummy_failure_jump:
case Cupdate_failure_jump:
case Cstar_jump:
{
a = (unsigned char)code[pos++];
a |= (unsigned char)code[pos++] << 8;
pos += (int)SHORT(a);
if (visited[pos])
{
/* argh... the regexp contains empty loops. This is not
good, as this may cause a failure stack overflow when
matching. Oh well. */
/* this path leads nowhere; pursue other paths. */
return;
}
visited[pos] = 1;
break;
}
case Cfailure_jump:
{
a = (unsigned char)code[pos++];
a |= (unsigned char)code[pos++] << 8;
a = pos + (int)SHORT(a);
re_compile_fastmap_aux(code, a, visited, can_be_null, fastmap);
break;
}
case Crepeat1:
{
pos += 2;
break;
}
default:
{
PyErr_SetString(PyExc_SystemError, "Unknown regex opcode: memory corrupted?");
return;
/*NOTREACHED*/
}
}
}
static int re_do_compile_fastmap(unsigned char *buffer, int used, int pos,
unsigned char *can_be_null,
unsigned char *fastmap)
{
unsigned char small_visited[512], *visited;
if (used <= sizeof(small_visited))
visited = small_visited;
else
{
visited = malloc(used);
if (!visited)
return 0;
}
*can_be_null = 0;
memset(fastmap, 0, 256);
memset(visited, 0, used);
re_compile_fastmap_aux(buffer, pos, visited, can_be_null, fastmap);
if (visited != small_visited)
free(visited);
return 1;
}
void re_compile_fastmap(regexp_t bufp)
{
if (!bufp->fastmap || bufp->fastmap_accurate)
return;
assert(bufp->used > 0);
if (!re_do_compile_fastmap(bufp->buffer,
bufp->used,
0,
&bufp->can_be_null,
bufp->fastmap))
return;
if (PyErr_Occurred()) return;
if (bufp->buffer[0] == Cbol)
bufp->anchor = 1; /* begline */
else
if (bufp->buffer[0] == Cbegbuf)
bufp->anchor = 2; /* begbuf */
else
bufp->anchor = 0; /* none */
bufp->fastmap_accurate = 1;
}
/*
* star is coded as:
* 1: failure_jump 2
* ... code for operand of star
* star_jump 1
* 2: ... code after star
*
* We change the star_jump to update_failure_jump if we can determine
* that it is safe to do so; otherwise we change it to an ordinary
* jump.
*
* plus is coded as
*
* jump 2
* 1: failure_jump 3
* 2: ... code for operand of plus
* star_jump 1
* 3: ... code after plus
*
* For star_jump considerations this is processed identically to star.
*
*/
static int re_optimize_star_jump(regexp_t bufp, unsigned char *code)
{
unsigned char map[256];
unsigned char can_be_null;
unsigned char *p1;
unsigned char *p2;
unsigned char ch;
int a;
int b;
int num_instructions = 0;
a = (unsigned char)*code++;
a |= (unsigned char)*code++ << 8;
a = (int)SHORT(a);
p1 = code + a + 3; /* skip the failure_jump */
/* Check that the jump is within the pattern */
if (p1<bufp->buffer || bufp->buffer+bufp->used<p1)
{
PyErr_SetString(PyExc_SystemError, "Regex VM jump out of bounds (failure_jump opt)");
return 0;
}
assert(p1[-3] == Cfailure_jump);
p2 = code;
/* p1 points inside loop, p2 points to after loop */
if (!re_do_compile_fastmap(bufp->buffer, bufp->used,
(int)(p2 - bufp->buffer),
&can_be_null, map))
goto make_normal_jump;
/* If we might introduce a new update point inside the
* loop, we can't optimize because then update_jump would
* update a wrong failure point. Thus we have to be
* quite careful here.
*/
/* loop until we find something that consumes a character */
loop_p1:
num_instructions++;
switch (*p1++)
{
case Cbol:
case Ceol:
case Cbegbuf:
case Cendbuf:
case Cwordbeg:
case Cwordend:
case Cwordbound:
case Cnotwordbound:
{
goto loop_p1;
}
case Cstart_memory:
case Cend_memory:
{
p1++;
goto loop_p1;
}
case Cexact:
{
ch = (unsigned char)*p1++;
if (map[(int)ch])
goto make_normal_jump;
break;
}
case Canychar:
{
for (b = 0; b < 256; b++)
if (b != '\n' && map[b])
goto make_normal_jump;
break;
}
case Cset:
{
for (b = 0; b < 256; b++)
if ((p1[b >> 3] & (1 << (b & 7))) && map[b])
goto make_normal_jump;
p1 += 256/8;
break;
}
default:
{
goto make_normal_jump;
}
}
/* now we know that we can't backtrack. */
while (p1 != p2 - 3)
{
num_instructions++;
switch (*p1++)
{
case Cend:
{
return 0;
}
case Cbol:
case Ceol:
case Canychar:
case Cbegbuf:
case Cendbuf:
case Cwordbeg:
case Cwordend:
case Cwordbound:
case Cnotwordbound:
{
break;
}
case Cset:
{
p1 += 256/8;
break;
}
case Cexact:
case Cstart_memory:
case Cend_memory:
case Cmatch_memory:
case Csyntaxspec:
case Cnotsyntaxspec:
{
p1++;
break;
}
case Cjump:
case Cstar_jump:
case Cfailure_jump:
case Cupdate_failure_jump:
case Cdummy_failure_jump:
{
goto make_normal_jump;
}
default:
{
return 0;
}
}
}
/* make_update_jump: */
code -= 3;
a += 3; /* jump to after the Cfailure_jump */
code[0] = Cupdate_failure_jump;
code[1] = a & 0xff;
code[2] = a >> 8;
if (num_instructions > 1)
return 1;
assert(num_instructions == 1);
/* if the only instruction matches a single character, we can do
* better */
p1 = code + 3 + a; /* start of sole instruction */
if (*p1 == Cset || *p1 == Cexact || *p1 == Canychar ||
*p1 == Csyntaxspec || *p1 == Cnotsyntaxspec)
code[0] = Crepeat1;
return 1;
make_normal_jump:
code -= 3;
*code = Cjump;
return 1;
}
static int re_optimize(regexp_t bufp)
{
unsigned char *code;
code = bufp->buffer;
while(1)
{
switch (*code++)
{
case Cend:
{
return 1;
}
case Canychar:
case Cbol:
case Ceol:
case Cbegbuf:
case Cendbuf:
case Cwordbeg:
case Cwordend:
case Cwordbound:
case Cnotwordbound:
{
break;
}
case Cset:
{
code += 256/8;
break;
}
case Cexact:
case Cstart_memory:
case Cend_memory:
case Cmatch_memory:
case Csyntaxspec:
case Cnotsyntaxspec:
{
code++;
break;
}
case Cstar_jump:
{
if (!re_optimize_star_jump(bufp, code))
{
return 0;
}
/* fall through */
}
case Cupdate_failure_jump:
case Cjump:
case Cdummy_failure_jump:
case Cfailure_jump:
case Crepeat1:
{
code += 2;
break;
}
default:
{
return 0;
}
}
}
}
#define NEXTCHAR(var) \
{ \
if (pos >= size) \
goto ends_prematurely; \
(var) = regex[pos]; \
pos++; \
}
#define ALLOC(amount) \
{ \
if (pattern_offset+(amount) > alloc) \
{ \
alloc += 256 + (amount); \
pattern = realloc(pattern, alloc); \
if (!pattern) \
goto out_of_memory; \
} \
}
#define STORE(ch) pattern[pattern_offset++] = (ch)
#define CURRENT_LEVEL_START (starts[starts_base + current_level])
#define SET_LEVEL_START starts[starts_base + current_level] = pattern_offset
#define PUSH_LEVEL_STARTS \
if (starts_base < (MAX_NESTING-1)*NUM_LEVELS) \
starts_base += NUM_LEVELS; \
else \
goto too_complex \
#define POP_LEVEL_STARTS starts_base -= NUM_LEVELS
#define PUT_ADDR(offset,addr) \
{ \
int disp = (addr) - (offset) - 2; \
pattern[(offset)] = disp & 0xff; \
pattern[(offset)+1] = (disp>>8) & 0xff; \
}
#define INSERT_JUMP(pos,type,addr) \
{ \
int a, p = (pos), t = (type), ad = (addr); \
for (a = pattern_offset - 1; a >= p; a--) \
pattern[a + 3] = pattern[a]; \
pattern[p] = t; \
PUT_ADDR(p+1,ad); \
pattern_offset += 3; \
}
#define SETBIT(buf,offset,bit) (buf)[(offset)+(bit)/8] |= (1<<((bit) & 7))
#define SET_FIELDS \
{ \
bufp->allocated = alloc; \
bufp->buffer = pattern; \
bufp->used = pattern_offset; \
}
#define GETHEX(var) \
{ \
unsigned char gethex_ch, gethex_value; \
NEXTCHAR(gethex_ch); \
gethex_value = hex_char_to_decimal(gethex_ch); \
if (gethex_value == 16) \
goto hex_error; \
NEXTCHAR(gethex_ch); \
gethex_ch = hex_char_to_decimal(gethex_ch); \
if (gethex_ch == 16) \
goto hex_error; \
(var) = gethex_value * 16 + gethex_ch; \
}
#define ANSI_TRANSLATE(ch) \
{ \
switch (ch) \
{ \
case 'a': \
case 'A': \
{ \
ch = 7; /* audible bell */ \
break; \
} \
case 'b': \
case 'B': \
{ \
ch = 8; /* backspace */ \
break; \
} \
case 'f': \
case 'F': \
{ \
ch = 12; /* form feed */ \
break; \
} \
case 'n': \
case 'N': \
{ \
ch = 10; /* line feed */ \
break; \
} \
case 'r': \
case 'R': \
{ \
ch = 13; /* carriage return */ \
break; \
} \
case 't': \
case 'T': \
{ \
ch = 9; /* tab */ \
break; \
} \
case 'v': \
case 'V': \
{ \
ch = 11; /* vertical tab */ \
break; \
} \
case 'x': /* hex code */ \
case 'X': \
{ \
GETHEX(ch); \
break; \
} \
default: \
{ \
/* other characters passed through */ \
if (translate) \
ch = translate[(unsigned char)ch]; \
break; \
} \
} \
}
char *re_compile_pattern(unsigned char *regex, int size, regexp_t bufp)
{
int a;
int pos;
int op;
int current_level;
int level;
int opcode;
int pattern_offset = 0, alloc;
int starts[NUM_LEVELS * MAX_NESTING];
int starts_base;
int future_jumps[MAX_NESTING];
int num_jumps;
unsigned char ch = '\0';
unsigned char *pattern;
unsigned char *translate;
int next_register;
int paren_depth;
int num_open_registers;
int open_registers[RE_NREGS];
int beginning_context;
if (!re_compile_initialized)
re_compile_initialize();
bufp->used = 0;
bufp->fastmap_accurate = 0;
bufp->uses_registers = 1;
bufp->num_registers = 1;
translate = bufp->translate;
pattern = bufp->buffer;
alloc = bufp->allocated;
if (alloc == 0 || pattern == NULL)
{
alloc = 256;
pattern = malloc(alloc);
if (!pattern)
goto out_of_memory;
}
pattern_offset = 0;
starts_base = 0;
num_jumps = 0;
current_level = 0;
SET_LEVEL_START;
num_open_registers = 0;
next_register = 1;
paren_depth = 0;
beginning_context = 1;
op = -1;
/* we use Rend dummy to ensure that pending jumps are updated
(due to low priority of Rend) before exiting the loop. */
pos = 0;
while (op != Rend)
{
if (pos >= size)
op = Rend;
else
{
NEXTCHAR(ch);
if (translate)
ch = translate[(unsigned char)ch];
op = regexp_plain_ops[(unsigned char)ch];
if (op == Rquote)
{
NEXTCHAR(ch);
op = regexp_quoted_ops[(unsigned char)ch];
if (op == Rnormal && regexp_ansi_sequences)
ANSI_TRANSLATE(ch);
}
}
level = regexp_precedences[op];
/* printf("ch='%c' op=%d level=%d current_level=%d
curlevstart=%d\n", ch, op, level, current_level,
CURRENT_LEVEL_START); */
if (level > current_level)
{
for (current_level++; current_level < level; current_level++)
SET_LEVEL_START;
SET_LEVEL_START;
}
else
if (level < current_level)
{
current_level = level;
for (;num_jumps > 0 &&
future_jumps[num_jumps-1] >= CURRENT_LEVEL_START;
num_jumps--)
PUT_ADDR(future_jumps[num_jumps-1], pattern_offset);
}
switch (op)
{
case Rend:
{
break;
}
case Rnormal:
{
normal_char:
opcode = Cexact;
store_opcode_and_arg: /* opcode & ch must be set */
SET_LEVEL_START;
ALLOC(2);
STORE(opcode);
STORE(ch);
break;
}
case Ranychar:
{
opcode = Canychar;
store_opcode:
SET_LEVEL_START;
ALLOC(1);
STORE(opcode);
break;
}
case Rquote:
{
Py_FatalError("Rquote");
/*NOTREACHED*/
}
case Rbol:
{
if (!beginning_context) {
if (regexp_context_indep_ops)
goto op_error;
else
goto normal_char;
}
opcode = Cbol;
goto store_opcode;
}
case Reol:
{
if (!((pos >= size) ||
((regexp_syntax & RE_NO_BK_VBAR) ?
(regex[pos] == '\174') :
(pos+1 < size && regex[pos] == '\134' &&
regex[pos+1] == '\174')) ||
((regexp_syntax & RE_NO_BK_PARENS)?
(regex[pos] == ')'):
(pos+1 < size && regex[pos] == '\134' &&
regex[pos+1] == ')')))) {
if (regexp_context_indep_ops)
goto op_error;
else
goto normal_char;
}
opcode = Ceol;
goto store_opcode;
/* NOTREACHED */
break;
}
case Roptional:
{
if (beginning_context) {
if (regexp_context_indep_ops)
goto op_error;
else
goto normal_char;
}
if (CURRENT_LEVEL_START == pattern_offset)
break; /* ignore empty patterns for ? */
ALLOC(3);
INSERT_JUMP(CURRENT_LEVEL_START, Cfailure_jump,
pattern_offset + 3);
break;
}
case Rstar:
case Rplus:
{
if (beginning_context) {
if (regexp_context_indep_ops)
goto op_error;
else
goto normal_char;
}
if (CURRENT_LEVEL_START == pattern_offset)
break; /* ignore empty patterns for + and * */
ALLOC(9);
INSERT_JUMP(CURRENT_LEVEL_START, Cfailure_jump,
pattern_offset + 6);
INSERT_JUMP(pattern_offset, Cstar_jump, CURRENT_LEVEL_START);
if (op == Rplus) /* jump over initial failure_jump */
INSERT_JUMP(CURRENT_LEVEL_START, Cdummy_failure_jump,
CURRENT_LEVEL_START + 6);
break;
}
case Ror:
{
ALLOC(6);
INSERT_JUMP(CURRENT_LEVEL_START, Cfailure_jump,
pattern_offset + 6);
if (num_jumps >= MAX_NESTING)
goto too_complex;
STORE(Cjump);
future_jumps[num_jumps++] = pattern_offset;
STORE(0);
STORE(0);
SET_LEVEL_START;
break;
}
case Ropenpar:
{
SET_LEVEL_START;
if (next_register < RE_NREGS)
{
bufp->uses_registers = 1;
ALLOC(2);
STORE(Cstart_memory);
STORE(next_register);
open_registers[num_open_registers++] = next_register;
bufp->num_registers++;
next_register++;
}
paren_depth++;
PUSH_LEVEL_STARTS;
current_level = 0;
SET_LEVEL_START;
break;
}
case Rclosepar:
{
if (paren_depth <= 0)
goto parenthesis_error;
POP_LEVEL_STARTS;
current_level = regexp_precedences[Ropenpar];
paren_depth--;
if (paren_depth < num_open_registers)
{
bufp->uses_registers = 1;
ALLOC(2);
STORE(Cend_memory);
num_open_registers--;
STORE(open_registers[num_open_registers]);
}
break;
}
case Rmemory:
{
if (ch == '0')
goto bad_match_register;
assert(ch >= '0' && ch <= '9');
bufp->uses_registers = 1;
opcode = Cmatch_memory;
ch -= '0';
goto store_opcode_and_arg;
}
case Rextended_memory:
{
NEXTCHAR(ch);
if (ch < '0' || ch > '9')
goto bad_match_register;
NEXTCHAR(a);
if (a < '0' || a > '9')
goto bad_match_register;
ch = 10 * (a - '0') + ch - '0';
if (ch == 0 || ch >= RE_NREGS)
goto bad_match_register;
bufp->uses_registers = 1;
opcode = Cmatch_memory;
goto store_opcode_and_arg;
}
case Ropenset:
{
int complement;
int prev;
int offset;
int range;
int firstchar;
SET_LEVEL_START;
ALLOC(1+256/8);
STORE(Cset);
offset = pattern_offset;
for (a = 0; a < 256/8; a++)
STORE(0);
NEXTCHAR(ch);
if (translate)
ch = translate[(unsigned char)ch];
if (ch == '\136')
{
complement = 1;
NEXTCHAR(ch);
if (translate)
ch = translate[(unsigned char)ch];
}
else
complement = 0;
prev = -1;
range = 0;
firstchar = 1;
while (ch != '\135' || firstchar)
{
firstchar = 0;
if (regexp_ansi_sequences && ch == '\134')
{
NEXTCHAR(ch);
ANSI_TRANSLATE(ch);
}
if (range)
{
for (a = prev; a <= (int)ch; a++)
SETBIT(pattern, offset, a);
prev = -1;
range = 0;
}
else
if (prev != -1 && ch == '-')
range = 1;
else
{
SETBIT(pattern, offset, ch);
prev = ch;
}
NEXTCHAR(ch);
if (translate)
ch = translate[(unsigned char)ch];
}
if (range)
SETBIT(pattern, offset, '-');
if (complement)
{
for (a = 0; a < 256/8; a++)
pattern[offset+a] ^= 0xff;
}
break;
}
case Rbegbuf:
{
opcode = Cbegbuf;
goto store_opcode;
}
case Rendbuf:
{
opcode = Cendbuf;
goto store_opcode;
}
case Rwordchar:
{
opcode = Csyntaxspec;
ch = Sword;
goto store_opcode_and_arg;
}
case Rnotwordchar:
{
opcode = Cnotsyntaxspec;
ch = Sword;
goto store_opcode_and_arg;
}
case Rwordbeg:
{
opcode = Cwordbeg;
goto store_opcode;
}
case Rwordend:
{
opcode = Cwordend;
goto store_opcode;
}
case Rwordbound:
{
opcode = Cwordbound;
goto store_opcode;
}
case Rnotwordbound:
{
opcode = Cnotwordbound;
goto store_opcode;
}
default:
{
abort();
}
}
beginning_context = (op == Ropenpar || op == Ror);
}
if (starts_base != 0)
goto parenthesis_error;
assert(num_jumps == 0);
ALLOC(1);
STORE(Cend);
SET_FIELDS;
if(!re_optimize(bufp))
return "Optimization error";
return NULL;
op_error:
SET_FIELDS;
return "Badly placed special character";
bad_match_register:
SET_FIELDS;
return "Bad match register number";
hex_error:
SET_FIELDS;
return "Bad hexadecimal number";
parenthesis_error:
SET_FIELDS;
return "Badly placed parenthesis";
out_of_memory:
SET_FIELDS;
return "Out of memory";
ends_prematurely:
SET_FIELDS;
return "Regular expression ends prematurely";
too_complex:
SET_FIELDS;
return "Regular expression too complex";
}
#undef CHARAT
#undef NEXTCHAR
#undef GETHEX
#undef ALLOC
#undef STORE
#undef CURRENT_LEVEL_START
#undef SET_LEVEL_START
#undef PUSH_LEVEL_STARTS
#undef POP_LEVEL_STARTS
#undef PUT_ADDR
#undef INSERT_JUMP
#undef SETBIT
#undef SET_FIELDS
#define PREFETCH if (text == textend) goto fail
#define NEXTCHAR(var) \
PREFETCH; \
var = (unsigned char)*text++; \
if (translate) \
var = translate[var]
int re_match(regexp_t bufp, unsigned char *string, int size, int pos,
regexp_registers_t old_regs)
{
unsigned char *code;
unsigned char *translate;
unsigned char *text;
unsigned char *textstart;
unsigned char *textend;
int a;
int b;
int ch;
int reg;
int match_end;
unsigned char *regstart;
unsigned char *regend;
int regsize;
match_state state;
assert(pos >= 0 && size >= 0);
assert(pos <= size);
text = string + pos;
textstart = string;
textend = string + size;
code = bufp->buffer;
translate = bufp->translate;
NEW_STATE(state, bufp->num_registers);
continue_matching:
switch (*code++)
{
case Cend:
{
match_end = text - textstart;
if (old_regs)
{
old_regs->start[0] = pos;
old_regs->end[0] = match_end;
if (!bufp->uses_registers)
{
for (a = 1; a < RE_NREGS; a++)
{
old_regs->start[a] = -1;
old_regs->end[a] = -1;
}
}
else
{
for (a = 1; a < bufp->num_registers; a++)
{
if ((GET_REG_START(state, a) == NULL) ||
(GET_REG_END(state, a) == NULL))
{
old_regs->start[a] = -1;
old_regs->end[a] = -1;
continue;
}
old_regs->start[a] = GET_REG_START(state, a) - textstart;
old_regs->end[a] = GET_REG_END(state, a) - textstart;
}
for (; a < RE_NREGS; a++)
{
old_regs->start[a] = -1;
old_regs->end[a] = -1;
}
}
}
FREE_STATE(state);
return match_end - pos;
}
case Cbol:
{
if (text == textstart || text[-1] == '\n')
goto continue_matching;
goto fail;
}
case Ceol:
{
if (text == textend || *text == '\n')
goto continue_matching;
goto fail;
}
case Cset:
{
NEXTCHAR(ch);
if (code[ch/8] & (1<<(ch & 7)))
{
code += 256/8;
goto continue_matching;
}
goto fail;
}
case Cexact:
{
NEXTCHAR(ch);
if (ch != (unsigned char)*code++)
goto fail;
goto continue_matching;
}
case Canychar:
{
NEXTCHAR(ch);
if (ch == '\n')
goto fail;
goto continue_matching;
}
case Cstart_memory:
{
reg = *code++;
SET_REG_START(state, reg, text, goto error);
goto continue_matching;
}
case Cend_memory:
{
reg = *code++;
SET_REG_END(state, reg, text, goto error);
goto continue_matching;
}
case Cmatch_memory:
{
reg = *code++;
regstart = GET_REG_START(state, reg);
regend = GET_REG_END(state, reg);
if ((regstart == NULL) || (regend == NULL))
goto fail; /* or should we just match nothing? */
regsize = regend - regstart;
if (regsize > (textend - text))
goto fail;
if(translate)
{
for (; regstart < regend; regstart++, text++)
if (translate[*regstart] != translate[*text])
goto fail;
}
else
for (; regstart < regend; regstart++, text++)
if (*regstart != *text)
goto fail;
goto continue_matching;
}
case Cupdate_failure_jump:
{
UPDATE_FAILURE(state, text, goto error);
/* fall to next case */
}
/* treat Cstar_jump just like Cjump if it hasn't been optimized */
case Cstar_jump:
case Cjump:
{
a = (unsigned char)*code++;
a |= (unsigned char)*code++ << 8;
code += (int)SHORT(a);
if (code<bufp->buffer || bufp->buffer+bufp->used<code) {
PyErr_SetString(PyExc_SystemError, "Regex VM jump out of bounds (Cjump)");
FREE_STATE(state);
return -2;
}
goto continue_matching;
}
case Cdummy_failure_jump:
{
unsigned char *failuredest;
a = (unsigned char)*code++;
a |= (unsigned char)*code++ << 8;
a = (int)SHORT(a);
assert(*code == Cfailure_jump);
b = (unsigned char)code[1];
b |= (unsigned char)code[2] << 8;
failuredest = code + (int)SHORT(b) + 3;
if (failuredest<bufp->buffer || bufp->buffer+bufp->used < failuredest) {
PyErr_SetString(PyExc_SystemError, "Regex VM jump out of bounds (Cdummy_failure_jump failuredest)");
FREE_STATE(state);
return -2;
}
PUSH_FAILURE(state, failuredest, NULL, goto error);
code += a;
if (code<bufp->buffer || bufp->buffer+bufp->used < code) {
PyErr_SetString(PyExc_SystemError, "Regex VM jump out of bounds (Cdummy_failure_jump code)");
FREE_STATE(state);
return -2;
}
goto continue_matching;
}
case Cfailure_jump:
{
a = (unsigned char)*code++;
a |= (unsigned char)*code++ << 8;
a = (int)SHORT(a);
if (code+a<bufp->buffer || bufp->buffer+bufp->used < code+a) {
PyErr_SetString(PyExc_SystemError, "Regex VM jump out of bounds (Cfailure_jump)");
FREE_STATE(state);
return -2;
}
PUSH_FAILURE(state, code + a, text, goto error);
goto continue_matching;
}
case Crepeat1:
{
unsigned char *pinst;
a = (unsigned char)*code++;
a |= (unsigned char)*code++ << 8;
a = (int)SHORT(a);
pinst = code + a;
if (pinst<bufp->buffer || bufp->buffer+bufp->used<pinst) {
PyErr_SetString(PyExc_SystemError, "Regex VM jump out of bounds (Crepeat1)");
FREE_STATE(state);
return -2;
}
/* pinst is sole instruction in loop, and it matches a
* single character. Since Crepeat1 was originally a
* Cupdate_failure_jump, we also know that backtracking
* is useless: so long as the single-character
* expression matches, it must be used. Also, in the
* case of +, we've already matched one character, so +
* can't fail: nothing here can cause a failure. */
switch (*pinst++)
{
case Cset:
{
if (translate)
{
while (text < textend)
{
ch = translate[(unsigned char)*text];
if (pinst[ch/8] & (1<<(ch & 7)))
text++;
else
break;
}
}
else
{
while (text < textend)
{
ch = (unsigned char)*text;
if (pinst[ch/8] & (1<<(ch & 7)))
text++;
else
break;
}
}
break;
}
case Cexact:
{
ch = (unsigned char)*pinst;
if (translate)
{
while (text < textend &&
translate[(unsigned char)*text] == ch)
text++;
}
else
{
while (text < textend && (unsigned char)*text == ch)
text++;
}
break;
}
case Canychar:
{
while (text < textend && (unsigned char)*text != '\n')
text++;
break;
}
case Csyntaxspec:
{
a = (unsigned char)*pinst;
if (translate)
{
while (text < textend &&
(SYNTAX(translate[*text]) & a) )
text++;
}
else
{
while (text < textend && (SYNTAX(*text) & a) )
text++;
}
break;
}
case Cnotsyntaxspec:
{
a = (unsigned char)*pinst;
if (translate)
{
while (text < textend &&
!(SYNTAX(translate[*text]) & a) )
text++;
}
else
{
while (text < textend && !(SYNTAX(*text) & a) )
text++;
}
break;
}
default:
{
FREE_STATE(state);
PyErr_SetString(PyExc_SystemError, "Unknown regex opcode: memory corrupted?");
return -2;
/*NOTREACHED*/
}
}
/* due to the funky way + and * are compiled, the top
* failure- stack entry at this point is actually a
* success entry -- update it & pop it */
UPDATE_FAILURE(state, text, goto error);
goto fail; /* i.e., succeed <wink/sigh> */
}
case Cbegbuf:
{
if (text == textstart)
goto continue_matching;
goto fail;
}
case Cendbuf:
{
if (text == textend)
goto continue_matching;
goto fail;
}
case Cwordbeg:
{
if (text == textend)
goto fail;
if (!(SYNTAX(*text) & Sword))
goto fail;
if (text == textstart)
goto continue_matching;
if (!(SYNTAX(text[-1]) & Sword))
goto continue_matching;
goto fail;
}
case Cwordend:
{
if (text == textstart)
goto fail;
if (!(SYNTAX(text[-1]) & Sword))
goto fail;
if (text == textend)
goto continue_matching;
if (!(SYNTAX(*text) & Sword))
goto continue_matching;
goto fail;
}
case Cwordbound:
{
/* Note: as in gnu regexp, this also matches at the
* beginning and end of buffer. */
if (text == textstart || text == textend)
goto continue_matching;
if ((SYNTAX(text[-1]) & Sword) ^ (SYNTAX(*text) & Sword))
goto continue_matching;
goto fail;
}
case Cnotwordbound:
{
/* Note: as in gnu regexp, this never matches at the
* beginning and end of buffer. */
if (text == textstart || text == textend)
goto fail;
if (!((SYNTAX(text[-1]) & Sword) ^ (SYNTAX(*text) & Sword)))
goto continue_matching;
goto fail;
}
case Csyntaxspec:
{
NEXTCHAR(ch);
if (!(SYNTAX(ch) & (unsigned char)*code++))
goto fail;
goto continue_matching;
}
case Cnotsyntaxspec:
{
NEXTCHAR(ch);
if (SYNTAX(ch) & (unsigned char)*code++)
goto fail;
goto continue_matching;
}
default:
{
FREE_STATE(state);
PyErr_SetString(PyExc_SystemError, "Unknown regex opcode: memory corrupted?");
return -2;
/*NOTREACHED*/
}
}
#if 0 /* This line is never reached --Guido */
abort();
#endif
/*
*NOTREACHED
*/
/* Using "break;" in the above switch statement is equivalent to "goto fail;" */
fail:
POP_FAILURE(state, code, text, goto done_matching, goto error);
goto continue_matching;
done_matching:
/* if(translated != NULL) */
/* free(translated); */
FREE_STATE(state);
return -1;
error:
/* if (translated != NULL) */
/* free(translated); */
FREE_STATE(state);
return -2;
}
#undef PREFETCH
#undef NEXTCHAR
int re_search(regexp_t bufp, unsigned char *string, int size, int pos,
int range, regexp_registers_t regs)
{
unsigned char *fastmap;
unsigned char *translate;
unsigned char *text;
unsigned char *partstart;
unsigned char *partend;
int dir;
int ret;
unsigned char anchor;
assert(size >= 0 && pos >= 0);
assert(pos + range >= 0 && pos + range <= size); /* Bugfix by ylo */
fastmap = bufp->fastmap;
translate = bufp->translate;
if (fastmap && !bufp->fastmap_accurate) {
re_compile_fastmap(bufp);
if (PyErr_Occurred()) return -2;
}
anchor = bufp->anchor;
if (bufp->can_be_null == 1) /* can_be_null == 2: can match null at eob */
fastmap = NULL;
if (range < 0)
{
dir = -1;
range = -range;
}
else
dir = 1;
if (anchor == 2) {
if (pos != 0)
return -1;
else
range = 0;
}
for (; range >= 0; range--, pos += dir)
{
if (fastmap)
{
if (dir == 1)
{ /* searching forwards */
text = string + pos;
partend = string + size;
partstart = text;
if (translate)
while (text != partend &&
!fastmap[(unsigned char) translate[(unsigned char)*text]])
text++;
else
while (text != partend && !fastmap[(unsigned char)*text])
text++;
pos += text - partstart;
range -= text - partstart;
if (pos == size && bufp->can_be_null == 0)
return -1;
}
else
{ /* searching backwards */
text = string + pos;
partstart = string + pos - range;
partend = text;
if (translate)
while (text != partstart &&
!fastmap[(unsigned char)
translate[(unsigned char)*text]])
text--;
else
while (text != partstart &&
!fastmap[(unsigned char)*text])
text--;
pos -= partend - text;
range -= partend - text;
}
}
if (anchor == 1)
{ /* anchored to begline */
if (pos > 0 && (string[pos - 1] != '\n'))
continue;
}
assert(pos >= 0 && pos <= size);
ret = re_match(bufp, string, size, pos, regs);
if (ret >= 0)
return pos;
if (ret == -2)
return -2;
}
return -1;
}
/*
** Local Variables:
** mode: c
** c-file-style: "python"
** End:
*/
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