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/*
* minilex.c
*
* High efficiency lexical state parser
*
* Copyright (C)2011-2014 Andy Green <andy@warmcat.com>
*
* Licensed under LGPL2
*
* Usage: gcc minilex.c -o minilex && ./minilex > lextable.h
*
* Run it twice to test parsing on the generated table on stderr
*/
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include "lextable-strings.h"
/*
* b7 = 0 = 1-byte seq
* 0x08 = fail
* 2-byte seq
* 0x00 - 0x07, then terminal as given in 2nd byte
3-byte seq
* no match: go fwd 3 byte, match: jump fwd by amt in +1/+2 bytes
* = 1 = 1-byte seq
* no match: die, match go fwd 1 byte
*/
unsigned char lextable[] = {
#include "lextable.h"
};
#define PARALLEL 30
struct state {
char c[PARALLEL];
int state[PARALLEL];
int count;
int bytepos;
int real_pos;
};
struct state state[1000];
int next = 1;
#define FAIL_CHAR 0x08
int lextable_decode(int pos, char c)
{
while (1) {
if (lextable[pos] & (1 << 7)) { /* 1-byte, fail on mismatch */
if ((lextable[pos] & 0x7f) != c)
return -1;
/* fall thru */
pos++;
if (lextable[pos] == FAIL_CHAR)
return -1;
return pos;
} else { /* b7 = 0, end or 3-byte */
if (lextable[pos] < FAIL_CHAR) /* terminal marker */
return pos;
if (lextable[pos] == c) /* goto */
return pos + (lextable[pos + 1]) +
(lextable[pos + 2] << 8);
/* fall thru goto */
pos += 3;
/* continue */
}
}
}
int main(void)
{
int n = 0;
int m = 0;
int prev;
char c;
int walk;
int saw;
int y;
int j;
int pos = 0;
while (n < sizeof(set) / sizeof(set[0])) {
m = 0;
walk = 0;
prev = 0;
if (set[n][0] == '\0') {
n++;
continue;
}
while (set[n][m]) {
saw = 0;
for (y = 0; y < state[walk].count; y++)
if (state[walk].c[y] == set[n][m]) {
/* exists -- go forward */
walk = state[walk].state[y];
saw = 1;
break;
}
if (saw)
goto again;
/* something we didn't see before */
state[walk].c[state[walk].count] = set[n][m];
state[walk].state[state[walk].count] = next;
state[walk].count++;
walk = next++;
again:
m++;
}
state[walk].c[0] = n++;
state[walk].state[0] = 0; /* terminal marker */
state[walk].count = 1;
}
walk = 0;
for (n = 0; n < next; n++) {
state[n].bytepos = walk;
walk += (2 * state[n].count);
}
/* compute everyone's position first */
pos = 0;
walk = 0;
for (n = 0; n < next; n++) {
state[n].real_pos = pos;
for (m = 0; m < state[n].count; m++) {
if (state[n].state[m] == 0)
pos += 2; /* terminal marker */
else { /* c is a character */
if ((state[state[n].state[m]].bytepos -
walk) == 2)
pos++;
else {
pos += 3;
if (m == state[n].count - 1)
pos++; /* fail */
}
}
walk += 2;
}
}
walk = 0;
pos = 0;
for (n = 0; n < next; n++) {
for (m = 0; m < state[n].count; m++) {
if (!m)
fprintf(stdout, "/* pos %04x: %3d */ ",
state[n].real_pos, n);
else
fprintf(stdout, " ");
y = state[n].c[m];
saw = state[n].state[m];
if (saw == 0) { // c is a terminal then
if (y > 0x7ff) {
fprintf(stderr, "terminal too big\n");
return 2;
}
fprintf(stdout, " 0x%02X, 0x%02X "
" "
"/* - terminal marker %2d - */,\n",
y >> 8, y & 0xff, y & 0x7f);
pos += 2;
walk += 2;
continue;
}
/* c is a character */
prev = y &0x7f;
if (prev < 32 || prev > 126)
prev = '.';
if ((state[saw].bytepos - walk) == 2) {
fprintf(stdout, " 0x%02X /* '%c' -> */,\n",
y | 0x80, prev);
pos++;
walk += 2;
continue;
}
j = state[saw].real_pos - pos;
if (j > 0xffff) {
fprintf(stderr,
"Jump > 64K bytes ahead (%d to %d)\n",
state[n].real_pos, state[saw].real_pos);
return 1;
}
fprintf(stdout, " 0x%02X /* '%c' */, 0x%02X, 0x%02X "
"/* (to 0x%04X state %3d) */,\n",
y, prev,
j & 0xff, j >> 8,
state[saw].real_pos, saw);
pos += 3;
if (m == state[n].count - 1) {
fprintf(stdout,
" 0x%02X, /* fail */\n",
FAIL_CHAR);
pos++; /* fail */
}
walk += 2;
}
}
fprintf(stdout, "/* total size %d bytes */\n", pos);
/*
* Try to parse every legal input string
*/
for (n = 0; n < sizeof(set) / sizeof(set[0]); n++) {
walk = 0;
m = 0;
y = -1;
if (set[n][0] == '\0')
continue;
fprintf(stderr, " trying '%s'\n", set[n]);
while (set[n][m]) {
walk = lextable_decode(walk, set[n][m]);
if (walk < 0) {
fprintf(stderr, "failed\n");
return 3;
}
if (lextable[walk] < FAIL_CHAR) {
y = (lextable[walk] << 8) + lextable[walk + 1];
break;
}
m++;
}
if (y != n) {
fprintf(stderr, "decode failed %d\n", y);
return 4;
}
}
fprintf(stderr, "All decode OK\n");
return 0;
}
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