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factor out recursion

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This commit is contained in:
Kyryl Melekhin
2022-04-21 14:13:14 +00:00
parent 8bee489e34
commit e26cb69a45
2 changed files with 51 additions and 47 deletions
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95
pike.c
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@@ -83,13 +83,6 @@ enum
RSPLIT,
};
/* Return codes for re_sizecode() and re_comp() */
enum {
RE_SUCCESS = 0,
RE_SYNTAX_ERROR = -2,
RE_UNSUPPORTED_SYNTAX = -3,
};
typedef struct rsub rsub;
struct rsub
{
@@ -184,25 +177,22 @@ void re_dumpcode(rcode *prog)
prog->unilen, prog->len, prog->splits, i);
}
/* next todo: crack and factor out this recursion,
no recursion will allow to make a meta macro out
of this, such that re_sizecode() becomes efficient
difficulty: very high, probably not any time soon */
static int _compilecode(const char **re_loc, rcode *prog, int sizecode)
static int _compilecode(const char *re_loc, rcode *prog, int sizecode)
{
const char *re = *re_loc;
const char *re = re_loc;
int *code = sizecode ? NULL : prog->insts;
int start = PC, term = PC;
int alt_label = 0, c;
int alt_stack[5000], altc = 0;
int alt_stack[4096], altc = 0;
int cap_stack[4096 * 5], capc = 0;
for (; *re && *re != ')';) {
while (*re) {
switch (*re) {
case '\\':
re++;
if (!*re) goto syntax_error; /* Trailing backslash */
if (!*re) return -1; /* Trailing backslash */
if (*re == '<' || *re == '>') {
if (re - *re_loc > 2 && re[-2] == '\\')
if (re - re_loc > 2 && re[-2] == '\\')
break;
EMIT(PC++, *re == '<' ? WBEG : WEND);
term = PC;
@@ -230,7 +220,7 @@ static int _compilecode(const char **re_loc, rcode *prog, int sizecode)
PC++; /* Skip "# of pairs" byte */
for (cnt = 0; *re != ']'; cnt++) {
if (*re == '\\') re++;
if (!*re) goto syntax_error;
if (!*re) return -1;
uc_code(c, re) EMIT(PC++, c);
uc_len(c, re)
if (re[c] == '-' && re[c+1] != ']')
@@ -244,29 +234,42 @@ static int _compilecode(const char **re_loc, rcode *prog, int sizecode)
term = PC;
int sub;
int capture = 1;
re++;
if (*re == '?') {
re++;
if (*re == ':') {
if (*(re+1) == '?') {
re += 2;
if (*re == ':')
capture = 0;
re++;
} else {
*re_loc = re;
return RE_UNSUPPORTED_SYNTAX;
}
else
return -1;
}
if (capture) {
sub = ++prog->sub;
EMIT(PC++, SAVE);
EMIT(PC++, sub);
}
int res = _compilecode(&re, prog, sizecode);
*re_loc = re;
if (res < 0) return res;
if (*re != ')') return RE_SYNTAX_ERROR;
if (capture) {
cap_stack[capc++] = capture;
cap_stack[capc++] = term;
cap_stack[capc++] = alt_label;
cap_stack[capc++] = start;
cap_stack[capc++] = altc;
alt_label = 0;
start = PC;
break;
case ')':
if (--capc-4 < 0) return -1;
if (code && alt_label) {
EMIT(alt_label, REL(alt_label, PC) + 1);
int _altc = cap_stack[capc];
for (int alts = altc; altc > _altc; altc--) {
int at = alt_stack[_altc+alts-altc]+(altc-_altc)*2;
EMIT(at, REL(at, PC) + 1);
}
}
start = cap_stack[--capc];
alt_label = cap_stack[--capc];
term = cap_stack[--capc];
if (cap_stack[--capc]) {
EMIT(PC++, SAVE);
EMIT(PC++, sub + prog->presub + 1);
EMIT(PC++, code[term+1] + prog->presub + 1);
}
break;
case '{':;
@@ -300,7 +303,7 @@ static int _compilecode(const char **re_loc, rcode *prog, int sizecode)
}
break;
case '?':
if (PC == term) goto syntax_error;
if (PC == term) return -1;
INSERT_CODE(term, 2, PC);
if (re[1] == '?') {
EMIT(term, RSPLIT);
@@ -311,7 +314,7 @@ static int _compilecode(const char **re_loc, rcode *prog, int sizecode)
term = PC;
break;
case '*':
if (PC == term) goto syntax_error;
if (PC == term) return -1;
INSERT_CODE(term, 2, PC);
EMIT(PC, JMP);
EMIT(PC + 1, REL(PC, term));
@@ -325,7 +328,7 @@ static int _compilecode(const char **re_loc, rcode *prog, int sizecode)
term = PC;
break;
case '+':
if (PC == term) goto syntax_error;
if (PC == term) return -1;
if (re[1] == '?') {
EMIT(PC, SPLIT);
re++;
@@ -363,11 +366,7 @@ static int _compilecode(const char **re_loc, rcode *prog, int sizecode)
EMIT(at, REL(at, PC) + 1);
}
}
*re_loc = re;
return RE_SUCCESS;
syntax_error:
*re_loc = re;
return RE_SYNTAX_ERROR;
return capc ? -1 : 0;
}
int re_sizecode(const char *re, int *nsub)
@@ -376,9 +375,8 @@ int re_sizecode(const char *re, int *nsub)
dummyprog.unilen = 3;
dummyprog.sub = 0;
int res = _compilecode(&re, &dummyprog, 1);
int res = _compilecode(re, &dummyprog, 1);
if (res < 0) return res;
if (*re) return RE_SYNTAX_ERROR;
*nsub = dummyprog.sub;
return dummyprog.unilen;
}
@@ -391,9 +389,8 @@ int re_comp(rcode *prog, const char *re, int nsubs)
prog->presub = nsubs;
prog->splits = 0;
int res = _compilecode(&re, prog, 0);
int res = _compilecode(re, prog, 0);
if (res < 0) return res;
if (*re) return RE_SYNTAX_ERROR;
int icnt = 0, scnt = SPLIT;
for (int i = 0; i < prog->unilen; i++)
switch (prog->insts[i]) {
@@ -424,7 +421,7 @@ int re_comp(rcode *prog, const char *re, int nsubs)
prog->presub = sizeof(rsub)+(sizeof(char*) * (nsubs + 1) * 2);
prog->sub = prog->presub * (prog->len - prog->splits + 3);
prog->sparsesz = scnt;
return RE_SUCCESS;
return 0;
}
#define newsub(init, copy) \
@@ -636,10 +633,14 @@ int main(int argc, char *argv[])
int sub_els;
int sz = re_sizecode(argv[1], &sub_els) * sizeof(int);
printf("Precalculated size: %d\n", sz);
if (sz < 0) {
printf("Error in re_sizecode\n");
return 1;
}
char code[sizeof(rcode)+sz];
rcode *_code = (rcode*)code;
if (re_comp(_code, argv[1], sub_els)) {
printf("Error in re_comp");
printf("Error in re_comp\n");
return 1;
}
re_dumpcode(_code);