Handling escape symbols

[ai]

Seems like we forget to add escape symbols support.

Here is an example: fo\a o should be parsed as a single token.

Here is a good description of escape symbols in CSS.

Tell me if you need anything from PostCSS core for this issue.

[alexander-akait]

👍

[nex3]

This is also an issue in string literals. For example, the CSS string "\"" is semantically identical to the string '"', but postcss-value-parser reports the (JS) value of the former as '\\"' (a string containing a backslash and a double quote) and the latter as '"' (a string containing only a double quote).

[romainmenke]

Our new css tokenizer also handles escape sequences correctly: https://www.npmjs.com/package/@csstools/css-tokenizer

escape sequences : https://runkit.com/romainmenke/escade-sequences-in-css

strings with double/single quotes : https://runkit.com/romainmenke/strings-in-css