php过滤函数trim实现原理
本文导语: 本节内容: php trim函数的原理剖析 代码示例: static inline int php_charmask(unsigned char *input, int len, char *mask TSRMLS_DC) { unsigned char *end; unsigned char c; int result = SUCCESS; memset(mask, 0, 256); for (end = input+len; input < end; input++) { ...
本节内容:
php trim函数的原理剖析
static inline int php_charmask(unsigned char *input, int len, char *mask TSRMLS_DC)
{
unsigned char *end;
unsigned char c;
int result = SUCCESS;
memset(mask, 0, 256);
for (end = input+len; input < end; input++) {
c=*input;
if ((input+3 < end) && input[1] == '.' && input[2] == '.'
&& input[3] >= c) {
memset(mask+c, 1, input[3] - c + 1);
input+=3;
} else if ((input+1 < end) && input[0] == '.' && input[1] == '.') {
/* Error, try to be as helpful as possible:
(a range ending/starting with '.' won't be captured here) */
if (end-len >= input) { /* there was no 'left' char */
php_error_docref(NULL TSRMLS_CC, E_WARNING, "Invalid '..'-range, no character to the left of '..'");
result = FAILURE;
continue;
}
if (input+2 >= end) { /* there is no 'right' char */
php_error_docref(NULL TSRMLS_CC, E_WARNING, "Invalid '..'-range, no character to the right of '..'");
result = FAILURE;
continue;
}
if (input[-1] > input[2]) { /* wrong order */
php_error_docref(NULL TSRMLS_CC, E_WARNING, "Invalid '..'-range, '..'-range needs to be incrementing");
result = FAILURE;
continue;
}
/* FIXME: better error (a..b..c is the only left possibility?) */
php_error_docref(NULL TSRMLS_CC, E_WARNING, "Invalid '..'-range");
result = FAILURE;
continue;
} else {
mask[c]=1;
}
}
return result;
}
/* }}} */
/* {{{ php_trim()
* mode 1 : trim left
* mode 2 : trim right
* mode 3 : trim left and right
* what indicates which chars are to be trimmed. NULL->default (' tnrv')
*/
PHPAPI char *php_trim(char *c, int len, char *what, int what_len, zval *return_value, int mode TSRMLS_DC)
{
register int i;
int trimmed = 0;
char mask[256];
if (what) {
php_charmask((unsigned char*)what, what_len, mask TSRMLS_CC);
} else {
php_charmask((unsigned char*)" nrtv", 6, mask TSRMLS_CC);
}
if (mode & 1) {
for (i = 0; i < len; i++) {
if (mask[(unsigned char)c[i]]) {
trimmed++;
} else {
break;
}
}
len -= trimmed;
c += trimmed;
}
if (mode & 2) {
for (i = len - 1; i >= 0; i--) {
if (mask[(unsigned char)c[i]]) {
len--;
} else {
break;
}
}
}
if (return_value) {
RETVAL_STRINGL(c, len, 1);
} else {
return estrndup(c, len);
}
return "";
}
/* }}} */
/* {{{ php_do_trim
* Base for trim(), rtrim() and ltrim() functions.
*/
static void php_do_trim(INTERNAL_FUNCTION_PARAMETERS, int mode)
{
char *str;
char *what = NULL;
int str_len, what_len = 0;
if (zend_parse_parameters(ZEND_NUM_ARGS() TSRMLS_CC, "s|s", &str, &str_len, &what, &what_len) == FAILURE) {
return;
}
php_trim(str, str_len, what, what_len, return_value, mode TSRMLS_CC);
}
/* }}} */
/* {{{ proto string trim(string str [, string character_mask])
Strips whitespace from the beginning and end of a string */
PHP_FUNCTION(trim)
{
php_do_trim(INTERNAL_FUNCTION_PARAM_PASSTHRU, 3);
}
/* }}} */
/* {{{ proto string rtrim(string str [, string character_mask])
Removes trailing whitespace */
PHP_FUNCTION(rtrim)
{
php_do_trim(INTERNAL_FUNCTION_PARAM_PASSTHRU, 2);
}
/* }}} */
/* {{{ proto string ltrim(string str [, string character_mask])
Strips whitespace from the beginning of a string */
PHP_FUNCTION(ltrim)
{
php_do_trim(INTERNAL_FUNCTION_PARAM_PASSTHRU, 1);
}
/* }}} */