33 lines
945 B
Markdown
33 lines
945 B
Markdown
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The first idea can be to list the languages with `|` in-between.
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But that doesn't work right:
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```js run
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let regexp = /Java|JavaScript|PHP|C|C\+\+/g;
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let str = "Java, JavaScript, PHP, C, C++";
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alert( str.match(regexp) ); // Java,Java,PHP,C,C
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```
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The regular expression engine looks for alternations one-by-one. That is: first it checks if we have `match:Java`, otherwise -- looks for `match:JavaScript` and so on.
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As a result, `match:JavaScript` can never be found, just because `match:Java` is checked first.
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The same with `match:C` and `match:C++`.
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There are two solutions for that problem:
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1. Change the order to check the longer match first: `pattern:JavaScript|Java|C\+\+|C|PHP`.
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2. Merge variants with the same start: `pattern:Java(Script)?|C(\+\+)?|PHP`.
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In action:
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```js run
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let regexp = /Java(Script)?|C(\+\+)?|PHP/g;
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let str = "Java, JavaScript, PHP, C, C++";
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alert( str.match(regexp) ); // Java,JavaScript,PHP,C,C++
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```
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