Question

我希望仅使用不带引号的术语将|替换为OR，例如：

"this | that" | "the | other" -> "this | that" OR "the | other"

是的，我可以拆分空间或引用，得到一个数组并迭代它，并重建字符串，但这似乎......不优雅。所以也许有一种正则表达式方法可以通过计算"之前的|来实现这一点，显然奇数意味着|被引用，甚至意味着不加引号。（注意：如果至少有一个"，则只有"偶数才会开始处理。

Answer 1

正则表达式无法计算，但是可以用于确定是否存在奇数或偶数。在这种情况下的技巧是检查管道之后的引号，而不是它之前。

str = str.replace(/\|(?=(?:(?:[^"]*"){2})*[^"]*$)/g, "OR");

打破这一点，(?:[^"]*"){2}匹配下一对引号（如果有的话）以及介入的非引号。在您尽可能多地完成该操作后（可能为零），[^"]*$会消耗任何剩余的非引号，直到字符串结束。

当然，这假设文本格式正确。它也没有解决转义引号的问题，但如果你需要它也可以。

Answer 2

正则表达不计算在内。这就是解析器的用途。

Answer 3

您可能会发现Perl FAQ on this issue相关。

#!/usr/bin/perl

use strict;
use warnings;

my $x = qq{"this | that" | "the | other"};
print join('" OR "', split /" \| "/, $x), "\n";

Answer 4

您不需要计算，因为您不嵌套引号。这样做：

#!/usr/bin/perl

my $str = '" this \" | that" | "the | other" | "still | something | else"';
print "$str\n";

while($str =~ /^((?:[^"|\\]*|\\.|"(?:[^\\"]|\\.)*")*)\|/) {
        $str =~ s/^((?:[^"|\\]*|\\.|"(?:[^\\"]|\\.)*")*)\|/$1OR/;
}

print "$str\n";

现在，让我们解释一下这个表达。

^  -- means you'll always match everything from the beginning of the string, otherwise
      the match might start inside a quote, and break everything

(...)\|   -- this means you'll match a certain pattern, followed by a |, which appears
             escaped here; so when you replace it with $1OR, you keep everything, but
             replace the |.

(?:...)*  -- This is a non-matching group, which can be repeated multiple times; we
             use a group here so we can repeat multiple times alternative patterns.

[^"|\\]*  -- This is the first pattern. Anything that isn't a pipe, an escape character
             or a quote.

\\.       -- This is the second pattern. Basically, an escape character and anything
             that follows it.

"(?:...)*" -- This is the third pattern. Open quote, followed by a another
              non-matching group repeated multiple times, followed by a closing
              quote.

[^\\"]    -- This is the first pattern in the second non-matching group. It's anything
             except an escape character or a quote.

\\.       -- This is the second pattern in the second non-matching group. It's an
             escape character and whatever follows it.

结果如下：

" this \" | that" | "the | other" | "still | something | else"
" this \" | that" OR "the | other" OR "still | something | else"

Answer 5

另一种方法（类似于Alan M的工作答案）：

str = str.replace(/(".+?"|\w+)\s*\|\s*/g, '$1 OR ');

第一组内部的部分（为便于阅读而间隔）：

".+?"  |  \w+

...基本上是指，引用的东西或一个词。其余的意思是它后跟一个“|”包装在可选的空格中。替换是第一部分（“$ 1”表示第一组）后跟“OR”。

Answer 6

也许你正在寻找这样的东西：

(?<=^([^"]*"[^"]*")+[^"|]*)\|

Answer 7

谢谢大家。忽略提及这一点的道歉是javascript，并且不必引用条款，并且可以有任意数量的引用/未引用的术语，例如：

"this | that" | "the | other" | yet | another  -> "this | that" OR "the | other" OR yet OR another

丹尼尔，似乎是在球场，即基本上是匹配/按摩循环。谢谢你的详细解释。在js中，它看起来像一个split，一个术语数组上的forEach循环，将一个术语（在将一个术语改为OR之后）推回一个数组，然后重新连接。

Answer 8

@Alan M，运行良好，由于sqlite FTS功能稀疏而无需转义。

@epost，为简洁和优雅所接受的解决方案，谢谢。它只需要以更通用的形式用于unicode等。

(".+?"|[^\"\s]+)\s*\|\s*

Answer 9

我在C＃中的解决方案来计算引号，然后使用正则表达式来获取匹配项：

        // Count the number of quotes.
        var quotesOnly = Regex.Replace(searchText, @"[^""]", string.Empty);
        var quoteCount = quotesOnly.Length;
        if (quoteCount > 0)
        {
            // If the quote count is an odd number there's a missing quote.
            // Assume a quote is missing from the end - executive decision.
            if (quoteCount%2 == 1)
            {
                searchText += @"""";
            }

            // Get the matching groups of strings. Exclude the quotes themselves.
            // e.g. The following line:
            // "this and that" or then and "this or other"
            // will result in the following groups:
            // 1. "this and that"
            // 2. "or"
            // 3. "then"
            // 4. "and"
            // 5. "this or other"
            var matches = Regex.Matches(searchText, @"([^\""]*)", RegexOptions.Singleline);
            var list = new List<string>();
            foreach (var match in matches.Cast<Match>())
            {
                var value = match.Groups[0].Value.Trim();
                if (!string.IsNullOrEmpty(value))
                {
                    list.Add(value);
                }
            }

            // TODO: Do something with the list of strings.
       }

正则表达式：如何确定给定char之前的char出现的奇数/偶数？

9 个答案: