negative-lookbehind | 易学教程

Javascript: negative lookbehind equivalent?

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问题 Is there a way to achieve the equivalent of a negative lookbehind in javascript regular expressions? I need to match a string that does not start with a specific set of characters. It seems I am unable to find a regex that does this without failing if the matched part is found at the beginning of the string. Negative lookbehinds seem to be the only answer, but javascript doesn't have one. EDIT: This is the regex that I would like to work, but it doesn't: (?<!([abcdefg]))m So it would match

Javascript: negative lookbehind equivalent?

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Regular expression using negative lookbehind not working in Notepad++

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问题 I have a source file with literally hundreds of occurrences of strings flecha.jpg and flecha1.jpg , but I need to find occurrences of any other .jpg image (i.e. casa.jpg , moto.jpg , whatever) I have tried using a regular expression with negative lookbehind, like this: (?<!flecha|flecha1).jpg but it doesn't work! Notepad++ simply says that it is an invalid regular expression. I have tried the regex elsewhere and it works, here is an example so I guess it is a problem with NPP's handling of

Need variable width negative lookbehind replacement

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问题 I have looked at many questions here (and many more websites) and some provided hints but none gave me a definitive answer. I know regular expressions but I am far from being a guru. This particular question deals with regex in PHP. I need to locate words in a text that are not surrounded by a hyperlink of a given class. For example, I might have This <a href="blabblah" class="no_check">elephant</a> is green and this elephant is blue while this <a href="blahblah">elephant</a> is red. I would

How to explain the same structure expression `(?=\w{6,10})\d+ and (?=abc)ad`? [duplicate]

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问题 This question already has an answer here : Reference - What does this regex mean? (1 answer) Closed 2 years ago . debian@wifi:~$ echo "348dfgeccvdf" | grep -oP "\d+(?=\w{6,10})" 348 debian@wifi:~$ echo "348dfgeccvdf" | grep -oP "(?=\w{6,10})\d+" 348 For \d+(?=\w{6,10}) ,it is the standard positive look ahead expression. As Wiktor Stribiżew say in the post position and negative lookbehind The negative lookbehind syntax starts with (?<! and ends with the unescaped ) . Whether it appears at the

Negative Lookbehind JavaScript

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问题 I know that a lot of people have posted a similar question but with the g flag, none of the "hacks" seem to work for me properly (meaning they don't work most of the time) . Yes I want the g flag The regex I've made is: \~\![A-Za-z]+\ start(?:(?:(?:$|,)\ ?[\w]+)*?$)\:\{([\S\s]+?)(?:(?<!\\)\}\:end) This works fine when negative look-behind is supported. But when I do it in JavaScript. It doesn't support negative look behind. Here's the part where the problem lies: (?:(?<!\\)\}\:end) What it

Negative Lookbehind expression for not ending with exp : '\w+(?<!exp)\b' or '\w+\b(?<!exp)' [duplicate]

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问题 This question already has an answer here : Reference - What does this regex mean? (1 answer) Closed 2 years ago . For expression (?<!foo) ,Negative Lookbehind ,asserts that what immediately precedes the current position in the string is not foo. Now to match string not ending with characters abc . The formal expression is \w+(?<!abc)\b or \b\w+(?<!abc)\b . echo "xxabc jkl" | grep -oP '\w+(?<!abc)\b' jkl Let's try another form: \w+\b(?<!abc) . echo "xxabc jkl" | grep -oP '\w+\b(?<!abc)' jkl It

What's the easiest way to get an equivalent to GNU grep that supports negative lookbehinds?

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问题 I'm trying to grep through a bunch of files in nested subdirectories to look for regular expression matches; my regex requires negative lookbehind. Perl has negative lookbehind, but as far as I can tell GNU grep doesn't support negative lookbehinds. What's the easiest way to get an equivalent to GNU grep that supports negative lookbehinds? (I guess I could write my own mini-grep in Perl, but that doesn't seem like it should be necessary. My copy of the Perl Cookbook includes source for tcgrep

negative lookahead Regexp doesnt work in ES dsl query

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问题 The mapping of my Elastic search looks like below: { "settings": { "index": { "number_of_shards": "5", "number_of_replicas": "1" } }, "mappings": { "node": { "properties": { "field1": { "type": "keyword" }, "field2": { "type": "keyword" }, "query": { "properties": { "regexp": { "properties": { "field1": { "type": "keyword" }, "field2": { "type": "keyword" } } } } } } } } } Problem is : I am forming ES queries using elasticsearch_dsl Q(). It works perfectly fine in most of the cases when my

negative lookahead Regexp doesnt work in ES dsl query

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The mapping of my Elastic search looks like below: { "settings": { "index": { "number_of_shards": "5", "number_of_replicas": "1" } }, "mappings": { "node": { "properties": { "field1": { "type": "keyword" }, "field2": { "type": "keyword" }, "query": { "properties": { "regexp": { "properties": { "field1": { "type": "keyword" }, "field2": { "type": "keyword" } } } } } } } } } Problem is : I am forming ES queries using elasticsearch_dsl Q(). It works perfectly fine in most of the cases when my query contains any complex regexp. But it totally fails if it contains regexp character '!' in it. It