Flex regex tool

I am trying to match single line comment pattern in flex. Now my approach was using states. Link to code. Improve this question. AmigaAbattoir 9 9 silver badges 20 20 bronze badges. Add a comment. Active Oldest Votes. Character classes are not the same as sequences of characters: ab matches an a followed by a b [ab] matches either an a or a b Since character classes are just sets of characters, it is meaningless for the individual characters in the class to be repeated or optional, etc.

Improve this answer. How can I achieve this? Can you edit your answer to show some steps or hint at some ideas? Answer: any character other than backslash or newline, or a backslash followed by anything including newline.

But whatever solution you use, you need to carefully review the section in the flex manual about patterns. Meaningful words for a programming language are described by a regular language. An implementation for describing a regular language is regular expressions. An implementation for parsing text while looking for matches to regular expressions is a flex lexical analyzer.

Essentially, programming a flex lexer means defining various regular expressions which detail all of the possible words and characters that are meaningful in a correct program for your language.

To illustrate flex, BooleanLogicLanguage is an example language which a flex-based lexer will lexically analyze. For no reason in particular, the purpose of this language is to evaluate Boolean logic expressions. An example of a program made in BooleanLogicLanguage. This diagram is an example of what a correct program would look like in this BooleanLogicLanguage. The comment may span lines. This type of pattern is called trailing context.

See Limitations , regarding dangerous trailing context. The regular expressions listed above are grouped according to precedence, from highest precedence at the top to lowest at the bottom. Replace with:. Common Regular Expressions. Share on:. Beautifier And Minifier tools. CSS Minifier Make it minified, compressed by removing newlines, white spaces, comments and indentation. CSS Beautifier Beautify, format, prettify and make it more readable.