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regexpr.c
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regexpr.c
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/* regexpr.c
*
* Author: Tatu Ylonen <[email protected]>
*
* 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 [email protected]
*
* 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"
#include <assert.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]; \