在PHP中模拟LIKE [英] Simulating LIKE in PHP

问题描述

有没有一种方法可以用相同的语法在PHP中模拟SQL的LIKE运算符? (%和_通配符以及通用$escape转义符)? 这样具有:

Is there a way to simulate the LIKE operator of SQL in PHP with the same syntax? (% and _ wildcards and a generic $escape escape character)? So that having:

$value LIKE $string ESCAPE $escape

您可以使用不返回数据库就可以返回PHP评估的函数吗? (考虑已设置$value，$string和$escape值).

you can have a function that returns the PHP evaluation of that without using the database? (consider that the $value, $string and $escape values are already set).

推荐答案

好吧，经过很多娱乐和游戏，这是我想出的:

OK, after much fun and games here's what I have come up with:

function preg_sql_like ($input, $pattern, $escape = '\\') {

    // Split the pattern into special sequences and the rest
    $expr = '/((?:'.preg_quote($escape, '/').')?(?:'.preg_quote($escape, '/').'|%|_))/';
    $parts = preg_split($expr, $pattern, -1, PREG_SPLIT_DELIM_CAPTURE | PREG_SPLIT_NO_EMPTY);

    // Loop the split parts and convert/escape as necessary to build regex
    $expr = '/^';
    $lastWasPercent = FALSE;
    foreach ($parts as $part) {
        switch ($part) {
            case $escape.$escape:
                $expr .= preg_quote($escape, '/');
                break;
            case $escape.'%':
                $expr .= '%';
                break;
            case $escape.'_':
                $expr .= '_';
                break;
            case '%':
                if (!$lastWasPercent) {
                    $expr .= '.*?';
                }
                break;
            case '_':
                $expr .= '.';
                break;
            default:
                $expr .= preg_quote($part, '/');
                break;
        }
        $lastWasPercent = $part == '%';
    }
    $expr .= '$/i';

    // Look for a match and return bool
    return (bool) preg_match($expr, $input);

}

我无法打破它，也许您会找到可以的东西.我的与@nickb的主要区别在于，我的将输入表达式解析"为标记以生成正则表达式，而不是就地将其转换为正则表达式.

I can't break it, maybe you can find something that will. The main way in which mine differs from @nickb's is that mine "parses"(ish) the input expression into tokens to generate a regex, rather than converting it to a regex in situ.

该函数的前三个参数应该很容易解释. 第四项允许您传递 PCRE修饰符以影响用于比赛的最终正则表达式.我输入此代码的主要原因是允许您通过i，因此它不区分大小写-我想不出任何其他可以安全使用的修饰符，但事实并非如此. ^{在下面的评论中已删除}

The first 3 arguments to the function should be fairly self explanatory. The fourth allows you to pass PCRE modifiers to affect the final regex used for the match. The main reason I put this in is to allow you to pass i so it is case insensitive - I can't think of any other modifiers that will be safe to use but that may not be the case. ^{Removed per comments below}

函数仅返回一个布尔值，指示$input文本是否与$pattern匹配.

Function simply returns a boolean indicating whether the $input text matched the $pattern or not.

这是它的键盘

EDIT ，糟糕，现已修复. 新的键盘

EDIT Oops, was broken, now fixed. New codepad

编辑，删除了第四个参数，并根据下面的注释使所有匹配项均不区分大小写

EDIT Removed fourth argument and made all matches case-insensitive per comments below

编辑:一些小的修复/改进:

EDIT A couple of small fixes/improvements:

• 将字符串断言的开始/结尾添加到生成的正则表达式中
• 添加了对最后一个令牌的跟踪，以避免在生成的正则表达式中出现多个.*?序列

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