Tasmota/lib/libesp32/re1.5/thompson.c

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2021-11-25 21:57:37 +00:00
// Copyright 2007-2009 Russ Cox. All Rights Reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
#include "re1.5.h"
typedef struct Thread Thread;
struct Thread
{
char *pc;
};
typedef struct ThreadList ThreadList;
struct ThreadList
{
int n;
Thread t[1];
};
static Thread
thread(char *pc)
{
Thread t = {pc};
return t;
}
static ThreadList*
threadlist(int n)
{
return mal(sizeof(ThreadList)+n*sizeof(Thread));
}
static void
addthread(ThreadList *l, Thread t, Subject *input, const char *sp)
{
int off;
if(*t.pc & 0x80)
return; // already on list
*t.pc |= 0x80;
l->t[l->n] = t;
l->n++;
switch(*t.pc & 0x7f) {
case Jmp:
off = (signed char)t.pc[1];
t.pc += 2;
addthread(l, thread(t.pc + off), input, sp);
break;
case Split:
off = (signed char)t.pc[1];
t.pc += 2;
addthread(l, thread(t.pc), input, sp);
addthread(l, thread(t.pc + off), input, sp);
break;
case RSplit:
off = (signed char)t.pc[1];
t.pc += 2;
addthread(l, thread(t.pc + off), input, sp);
addthread(l, thread(t.pc), input, sp);
break;
case Save:
off = (unsigned char)t.pc[1];
t.pc += 2;
addthread(l, thread(t.pc), input, sp);
break;
case Bol:
if(sp == input->begin)
addthread(l, thread(t.pc + 1), input, sp);
break;
case Eol:
if(sp == input->end - 1)
addthread(l, thread(t.pc + 1), input, sp);
break;
}
}
int
re1_5_thompsonvm(ByteProg *prog, Subject *input, const char **subp, int nsubp, int is_anchored)
{
int i, len, matched;
ThreadList *clist, *nlist, *tmp;
char *pc;
const char *sp;
for(i=0; i<nsubp; i++)
subp[i] = nil;
len = prog->len;
clist = threadlist(len);
nlist = threadlist(len);
if(nsubp >= 1)
subp[0] = input->begin;
cleanmarks(prog);
addthread(clist, thread(HANDLE_ANCHORED(prog->insts, is_anchored)), input, input->begin);
matched = 0;
for(sp=input->begin;; sp++) {
if(clist->n == 0)
break;
// printf("%d(%02x).", (int)(sp - input->begin), *sp & 0xFF);
cleanmarks(prog);
for(i=0; i<clist->n; i++) {
pc = clist->t[i].pc;
// printf(" %d", (int)(pc - prog->insts));
if (inst_is_consumer(*pc & 0x7f)) {
// If we need to match a character, but there's none left,
// it's fail (we don't schedule current thread for continuation)
if(sp >= input->end)
continue;
}
switch(*pc++ & 0x7f) {
case Char:
if(*sp != *pc++)
break;
case Any:
addthread:
addthread(nlist, thread(pc), input, sp);
break;
case Class:
case ClassNot:
if (!_re1_5_classmatch(pc, sp))
break;
pc += *(unsigned char*)pc * 2 + 1;
goto addthread;
case NamedClass:
if (!_re1_5_namedclassmatch(pc, sp))
break;
pc++;
goto addthread;
case Match:
if(nsubp >= 2)
subp[1] = sp;
matched = 1;
goto BreakFor;
// Jmp, Split, Save handled in addthread, so that
// machine execution matches what a backtracker would do.
// This is discussed (but not shown as code) in
// Regular Expression Matching: the Virtual Machine Approach.
}
}
BreakFor:
// printf("\n");
tmp = clist;
clist = nlist;
nlist = tmp;
nlist->n = 0;
//if(sp >= input->end)
// break;
}
return matched;
}