postcss/lib/tokenize.js

var singleQuote  = "'".charCodeAt(0),
    doubleQuote  = '"'.charCodeAt(0),
    backslash    = '\\'.charCodeAt(0),
    slash        = '/'.charCodeAt(0),
    newline      = '\n'.charCodeAt(0),
    space        = ' '.charCodeAt(0),
    feed         = '\f'.charCodeAt(0),
    tab          = '\t'.charCodeAt(0),
    cr           = '\r'.charCodeAt(0),
    openBracket  = '('.charCodeAt(0),
    closeBracket = ')'.charCodeAt(0),
    openCurly    = '{'.charCodeAt(0),
    closeCurly   = '}'.charCodeAt(0),
    semicolon    = ';'.charCodeAt(0),
    asterisk     = '*'.charCodeAt(0),
    colon        = ':'.charCodeAt(0),
    at           = '@'.charCodeAt(0),
    atEnd        = /[ \n\t\r\{\(\)'"\\/]/g,
    wordEnd      = /[ \n\t\r\(\)\{\}:;@!'"\\]|\/(?=\*)/g,
    badBracket   = /.[\\\/\("'\n]/;

export default function (input) {
    var tokens = [];
    var css    = input.css.valueOf();

    var code, next, quote, lines, last, content, escape,
        nextLine, nextOffset, escaped, escapePos, bad;

    var length = css.length;
    var offset = -1;
    var line   =  1;
    var pos    =  0;

    var unclosed = function (what, end) {
        if ( input.safe ) {
            css += end;
            next = length - 1;
        } else {
            throw input.error('Unclosed ' + what, line, pos  - offset);
        }
    };

    while ( pos < length ) {
        code = css.charCodeAt(pos);

        if ( code == newline ) {
            offset = pos;
            line  += 1;
        }

        switch ( code ) {
            case newline:
            case space:
            case tab:
            case cr:
            case feed:
                next = pos;
                do {
                    next += 1;
                    code = css.charCodeAt(next);
                    if ( code == newline ) {
                        offset = next;
                        line  += 1;
                    }
                } while ( code == space   ||
                          code == newline ||
                          code == tab     ||
                          code == cr      ||
                          code == feed );

                tokens.push(['space', css.slice(pos, next)]);
                pos = next - 1;
                break;

            case openCurly:
                tokens.push(['{', '{', line, pos - offset]);
                break;

            case closeCurly:
                tokens.push(['}', '}', line, pos - offset]);
                break;

            case colon:
                tokens.push([':', ':', line, pos - offset]);
                break;

            case semicolon:
                tokens.push([';', ';', line, pos - offset]);
                break;

            case openBracket:
                next    = css.indexOf(')', pos + 1);
                content = css.slice(pos, next + 1);

                if ( next == -1 || badBracket.test(content) ) {
                    tokens.push(['(', '(', line, pos - offset]);
                } else {
                    tokens.push(['brackets', content,
                        line, pos  - offset,
                        line, next - offset
                    ]);
                    pos = next;
                }

                break;

            case closeBracket:
                tokens.push([')', ')', line, pos - offset]);
                break;

            case singleQuote:
            case doubleQuote:
                quote = code == singleQuote ? "'" : '"';
                next  = pos;
                do {
                    escaped = false;
                    next    = css.indexOf(quote, next + 1);
                    if ( next == -1 ) unclosed('quote', quote);
                    escapePos = next;
                    while ( css.charCodeAt(escapePos - 1) == backslash ) {
                        escapePos -= 1;
                        escaped = !escaped;
                    }
                } while ( escaped );

                tokens.push(['string', css.slice(pos, next + 1),
                    line, pos  - offset,
                    line, next - offset
                ]);
                pos = next;
                break;

            case at:
                atEnd.lastIndex = pos + 1;
                atEnd.test(css);
                if ( atEnd.lastIndex === 0 ) {
                    next = css.length - 1;
                } else {
                    next = atEnd.lastIndex - 2;
                }
                tokens.push(['at-word', css.slice(pos, next + 1),
                    line, pos  - offset,
                    line, next - offset
                ]);
                pos = next;
                break;

            case backslash:
                next   = pos;
                escape = true;
                while ( css.charCodeAt(next + 1) == backslash ) {
                    next  += 1;
                    escape = !escape;
                }
                code = css.charCodeAt(next + 1);
                if ( escape && (code != slash   &&
                                code != space   &&
                                code != newline &&
                                code != tab     &&
                                code != cr      &&
                                code != feed ) ) {
                    next += 1;
                }
                tokens.push(['word', css.slice(pos, next + 1),
                    line, pos  - offset,
                    line, next - offset
                ]);
                pos = next;
                break;

            default:
                if ( code == slash && css.charCodeAt(pos + 1) == asterisk ) {
                    next = css.indexOf('*/', pos + 2) + 1;
                    if ( next === 0 ) unclosed('comment', '*/');

                    content = css.slice(pos, next + 1);
                    lines   = content.split('\n');
                    last    = lines.length - 1;

                    if ( last > 0 ) {
                        nextLine   = line + last;
                        nextOffset = next - lines[last].length;
                    } else {
                        nextLine   = line;
                        nextOffset = offset;
                    }

                    tokens.push(['comment', content,
                        line,     pos  - offset,
                        nextLine, next - nextOffset
                    ]);

                    offset = nextOffset;
                    line   = nextLine;
                    pos    = next;

                } else {
                    wordEnd.lastIndex = pos + 1;
                    wordEnd.test(css);
                    if ( wordEnd.lastIndex === 0 ) {
                        next = css.length - 1;
                    } else {
                        next = wordEnd.lastIndex - 2;
                    }

                    tokens.push(['word', css.slice(pos, next + 1),
                        line, pos  - offset,
                        line, next - offset
                    ]);
                    pos = next;
                }

                break;
        }

        pos++;
    }

    return tokens;
}