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/*
* utils.c - Some helper code for debugging and error logging.
*/
#include "utils.h"
/*
* Helper function to skip past all spaces (and comments)
* Returns a pointer to the first non-space character.
*/
const char *after_spaces(const char *str)
{
// Skip whitespace and comments:
skip_whitespace:
switch (*str) {
case ' ': case '\r': case '\n': case '\t': {
++str;
goto skip_whitespace;
}
case '#': {
while (*str && *str != '\n') ++str;
goto skip_whitespace;
}
}
return str;
}
/*
* Return the first character after a valid BPEG name, or NULL if none is
* found.
*/
const char *after_name(const char *str)
{
if (*str == '^' || *str == '_' || *str == '$') {
return (str[1] == *str) ? &str[2] : &str[1];
}
if (!isalpha(*str)) return NULL;
for (++str; *str; ++str) {
if (!(isalnum(*str) || *str == '-'))
break;
}
return str;
}
/*
* Check if a character is found and if so, move past it.
*/
int matchchar(const char **str, char c)
{
const char *next = after_spaces(*str);
if (*next == c) {
*str = &next[1];
return 1;
} else {
return 0;
}
}
/*
* Process a string escape sequence for a character and return the
* character that was escaped.
* Set *end = the first character past the end of the escape sequence.
*/
char unescapechar(const char *escaped, const char **end)
{
size_t len = 1;
char ret = *escaped;
switch (*escaped) {
case 'a': ret = '\a'; break; case 'b': ret = '\b'; break;
case 'n': ret = '\n'; break; case 'r': ret = '\r'; break;
case 't': ret = '\t'; break; case 'v': ret = '\v'; break;
case 'e': ret = '\033'; break;
case 'x': { // Hex
static const char hextable[255] = {
['0']=0x10, ['1']=0x1, ['2']=0x2, ['3']=0x3, ['4']=0x4,
['5']=0x5, ['6']=0x6, ['7']=0x7, ['8']=0x8, ['9']=0x9,
['a']=0xa, ['b']=0xb, ['c']=0xc, ['d']=0xd, ['e']=0xe, ['f']=0xf,
['A']=0xa, ['B']=0xb, ['C']=0xc, ['D']=0xd, ['E']=0xe, ['F']=0xf,
};
if (hextable[(int)escaped[1]] && hextable[(int)escaped[2]]) {
ret = (hextable[(int)escaped[1]] << 4) | (hextable[(int)escaped[2]] & 0xF);
len = 3;
}
break;
}
case '0': case '1': case '2': case '3': case '4': case '5': case '6': case '7': { // Octal
ret = escaped[0] - '0';
if ('0' <= escaped[1] && escaped[1] <= '7') {
++len;
ret = (ret << 3) | (escaped[1] - '0');
if ('0' <= escaped[2] && escaped[2] <= '7') {
++len;
ret = (ret << 3) | (escaped[2] - '0');
}
}
break;
}
default: break;
}
*end = &escaped[len];
return ret;
}
/*
* Write an unescaped version of `src` to `dest` (at most bufsize-1 chars,
* terminated by a null byte)
*/
size_t unescape_string(char *dest, const char *src, size_t bufsize)
{
size_t len = 0;
#define PUT(c) do { *(dest++) = (char)(c); ++len; } while (0)
for ( ; *src && len < bufsize; ++src) {
if (*src != '\\') {
PUT(*src);
continue;
}
++src;
switch (*src) {
case 'a': PUT('\a'); break; case 'b': PUT('\b'); break;
case 'n': PUT('\n'); break; case 'r': PUT('\r'); break;
case 't': PUT('\t'); break; case 'v': PUT('\v'); break;
case 'e': PUT('\033'); break;
case 'x': { // Hex
static const char hextable[255] = {
['0']=0x10, ['1']=0x1, ['2']=0x2, ['3']=0x3, ['4']=0x4,
['5']=0x5, ['6']=0x6, ['7']=0x7, ['8']=0x8, ['9']=0x9,
['a']=0xa, ['b']=0xb, ['c']=0xc, ['d']=0xd, ['e']=0xe, ['f']=0xf,
['A']=0xa, ['B']=0xb, ['C']=0xc, ['D']=0xd, ['E']=0xe, ['F']=0xf,
};
if (hextable[(int)src[1]] && hextable[(int)src[2]]) {
PUT((hextable[(int)src[1]] << 4) | (hextable[(int)src[2]] & 0xF));
src += 2;
}
break;
}
case '0': case '1': case '2': case '3': case '4': case '5': case '6': case '7': { // Octal
int c = *src - '0';
if ('0' <= src[1] && src[1] <= '7') {
++src;
c = (c << 3) | (*src - '0');
if ('0' <= src[1] && src[1] <= '7' && (c << 3) < 256) {
++src;
c = (c << 3) | (*src - '0');
}
}
PUT(c);
break;
}
default: PUT(*src); break;
}
}
*dest = '\0';
return len;
#undef PUT
}
// vim: ts=4 sw=0 et cino=L2,l1,(0,W4,m1
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