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copied!<blockquote> <p><code>"[^\\']"</code><br> Second, the escaped apostrophe. Why would you need to escape the apostrophe?</p> </blockquote> <p>Firstly note that In Emacs regexp syntax, <code>\`</code> matches the start of the string, and <code>\'</code> matches the end of the string. In multi-line strings this is different to the more familiar <code>^</code> and <code>$</code>, which match the beginning of a line and the end of a line.</p> <p>However that is not relevant within a character alternative (square brackets), so this sequence is actually matching any character other than a backslash or an apostrophe.</p> <p><strong>Edit:</strong></p> <p>So from the comments, this is still causing confusion, so let's break it down:</p> <p><code>"'\\(?:[^\\']\\|\\(?:\\\\.\\)\\)*'"</code></p> <p>That code evaluates to this string/regexp:</p> <p><code>'\(?:[^\']\|\(?:\\.\)\)*'</code></p> <p><code>'</code> matches an apostrophe</p> <p><code>\(?:foo\)*</code> matches zero or more <code>foo</code></p> <p><code>foo\|bar</code> matches either of <code>foo</code> or <code>bar</code></p> <p><code>[^\']</code> matches any character other than a backslash or an apostrophe</p> <p><code>\(?:\\.\)</code> could (in this case, being a non-capturing group which occurs exactly once) be rewritten as simply <code>\\.</code>, and matches a backslash followed by any character other than a newline.</p> <p><code>'</code> matches an apostrophe</p> <p>So the whole thing matches a single-quoted string in which:</p> <ul> <li>any other single-quotes must each be preceded by a backslash</li> <li>any backslash must be paired with another non-newline character (which could also be a backslash)</li> </ul> <p>Which of course sounds like a typical string syntax in which backslashes can be used to escape special characters, including backslashes themselves and any instances of the delimiting quote character.</p>

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