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Cleaned up backslash escape code

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This commit is contained in:
Bruce Hill 2020-09-08 01:25:27 -07:00
parent 70d218d211
commit 34b28d5d63
1 changed files with 63 additions and 48 deletions
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111
bpeg.c
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@ -323,6 +323,48 @@ static vm_op_t *expand_choices(vm_op_t *first)
return expand_choices(choice);
}
static char escapechar(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 '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;
}
/*
* Compile a string of BPEG code into virtual machine opcodes
*/
static vm_op_t *compile_bpeg(const char *str)
{
if (!*str) return NULL;
@ -369,43 +411,7 @@ static vm_op_t *compile_bpeg(const char *str)
check(*str, "Expected escape after '\\'");
op->op = VM_STRING;
op->len = 1;
char c[2] = {*str, '\0'};
++str;
switch (c[0]) {
case 'a': c[0] = '\a'; break;
case 'b': c[0] = '\b'; break;
case 'n': c[0] = '\n'; break;
case 'r': c[0] = '\r'; break;
case 't': c[0] = '\t'; break;
case 'v': c[0] = '\v'; 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)str[1]] && hextable[(int)str[2]])
c[0] = (hextable[(int)str[1]] << 4) | (hextable[(int)str[2]] & 0xF);
break;
}
case '0': case '1': case '2': case '3': case '4': case '5': case '6': case '7': { // Octal
c[0] = c[0] - '0';
++str;
if ('0' <= *str && *str <= '7') {
c[0] = (c[0] << 3) | (*str - '0');
++str;
}
if ('0' <= *str && *str <= '7') {
c[0] = (c[0] << 3) | (*str - '0');
++str;
}
break;
}
default: {
check(0, "Invalid escape sequence");
}
}
char c[2] = {escapechar(str, &str), '\0'};
op->args.s = strdup(c);
break;
}
@ -615,19 +621,24 @@ static vm_op_t *compile_bpeg(const char *str)
str = after_spaces(str);
char quote = *str;
++str;
check(quote == '\'' || quote == '"',
"Expected string literal for replacement");
const char *replacement = str;
for (; *str && *str != quote; str++) {
if (*str == '\\') {
check(str[1], "Expected more string contents after backslash");
++str;
const char *replacement;
if (quote == '}') {
replacement = strdup("");
} else {
++str;
check(quote == '\'' || quote == '"',
"Expected string literal for replacement");
replacement = str;
for (; *str && *str != quote; str++) {
if (*str == '\\') {
check(str[1], "Expected more string contents after backslash");
++str;
}
}
replacement = strndup(replacement, (size_t)(str-replacement));
++str;
str = after_spaces(str);
}
replacement = strndup(replacement, (size_t)(str-replacement));
++str;
str = after_spaces(str);
check(*str == '}', "Expected a closing '}'");
++str;
op->op = VM_REPLACE;
@ -755,6 +766,10 @@ static void print_match(match_t *m, const char *color)
print_match(cap, "\033[0;7;35m");
printf("\033[0;7;34m");
}
} else if (*r == '\\') {
++r;
fputc(escapechar(r, &r), stdout);
--r;
} else {
fputc(*r, stdout);
}