    001/*
    002 * YUI Compressor
    003 * http://developer.yahoo.com/yui/compressor/
    004 * Author: Julien Lecomte -  http://www.julienlecomte.net/
    005 * Author: Isaac Schlueter - http://foohack.com/
    006 * Author: Stoyan Stefanov - http://phpied.com/
    007 * Contributor: Dan Beam - http://danbeam.org/
    008 * Copyright (c) 2013 Yahoo! Inc.  All rights reserved.
    009 * The copyrights embodied in the content of this file are licensed
    010 * by Yahoo! Inc. under the BSD (revised) open source license.
    011 */
    012package com.yahoo.platform.yui.compressor;
    013
    014import java.io.IOException;
    015import java.io.Reader;
    016import java.io.Writer;
    017import java.util.ArrayList;
    018import java.util.regex.Matcher;
    019import java.util.regex.Pattern;
    020
    021public class CssCompressor {
    022
    023    private StringBuffer srcsb = new StringBuffer();
    024
    025    public CssCompressor(Reader in) throws IOException {
    026        // Read the stream...
    027        int c;
    028        while ((c = in.read()) != -1) {
    029            srcsb.append((char) c);
    030        }
    031    }
    032
    033    // Leave data urls alone to increase parse performance.
    034    protected String extractDataUrls(String css, ArrayList preservedTokens) {
    035
    036        int maxIndex = css.length() - 1;
    037        int appendIndex = 0;
    038
    039        StringBuffer sb = new StringBuffer();
    040
    041        Pattern p = Pattern.compile("(?i)url\\(\\s*([\"']?)data\\:");
    042        Matcher m = p.matcher(css);
    043
    044        /*
    045         * Since we need to account for non-base64 data urls, we need to handle
    046         * ' and ) being part of the data string. Hence switching to indexOf,
    047         * to determine whether or not we have matching string terminators and
    048         * handling sb appends directly, instead of using matcher.append* methods.
    049         */
    050
    051        while (m.find()) {
    052
    053            int startIndex = m.start() + 4;      // "url(".length()
    054            String terminator = m.group(1);     // ', " or empty (not quoted)
    055
    056            if (terminator.length() == 0) {
    057                terminator = ")";
    058            }
    059
    060            boolean foundTerminator = false;
    061
    062            int endIndex = m.end() - 1;
    063            while(foundTerminator == false && endIndex+1 <= maxIndex) {
    064                endIndex = css.indexOf(terminator, endIndex+1);
    065
    066                if ((endIndex > 0) && (css.charAt(endIndex-1) != '\\')) {
    067                    foundTerminator = true;
    068                    if (!")".equals(terminator)) {
    069                        endIndex = css.indexOf(")", endIndex);
    070                    }
    071                }
    072            }
    073
    074            // Enough searching, start moving stuff over to the buffer
    075            sb.append(css.substring(appendIndex, m.start()));
    076
    077            if (foundTerminator) {
    078                String token = css.substring(startIndex, endIndex);
    079                token = token.replaceAll("\\s+", "");
    080                preservedTokens.add(token);
    081
    082                String preserver = "url(___YUICSSMIN_PRESERVED_TOKEN_" + (preservedTokens.size() - 1) + "___)";
    083                sb.append(preserver);
    084
    085                appendIndex = endIndex + 1;
    086            } else {
    087                // No end terminator found, re-add the whole match. Should we throw/warn here?
    088                sb.append(css.substring(m.start(), m.end()));
    089                appendIndex = m.end();
    090            }
    091        }
    092
    093        sb.append(css.substring(appendIndex));
    094
    095        return sb.toString();
    096    }
    097
    098    private String preserveOldIESpecificMatrixDefinition(String css, ArrayList preservedTokens) {
    099        StringBuffer sb = new StringBuffer();
    100        Pattern p = Pattern.compile("\\s*filter:\\s*progid:DXImageTransform.Microsoft.Matrix\\(([^\\)]+)\\);");
    101        Matcher m = p.matcher(css);
    102        while (m.find()) {
    103            String token = m.group(1);
    104            preservedTokens.add(token);
    105            String preserver = "___YUICSSMIN_PRESERVED_TOKEN_" + (preservedTokens.size() - 1) + "___";
    106            m.appendReplacement(sb, "filter:progid:DXImageTransform.Microsoft.Matrix(" + preserver + ");");
    107        }
    108        m.appendTail(sb);
    109        return sb.toString();
    110    }
    111
    112    public void compress(Writer out, int linebreakpos)
    113            throws IOException {
    114
    115        Pattern p;
    116        Matcher m;
    117        String css = srcsb.toString();
    118
    119        int startIndex = 0;
    120        int endIndex = 0;
    121        int i = 0;
    122        int max = 0;
    123        ArrayList preservedTokens = new ArrayList(0);
    124        ArrayList comments = new ArrayList(0);
    125        String token;
    126        int totallen = css.length();
    127        String placeholder;
    128
    129        css = this.extractDataUrls(css, preservedTokens);
    130
    131        StringBuffer sb = new StringBuffer(css);
    132
    133        // collect all comment blocks...
    134        while ((startIndex = sb.indexOf("/*", startIndex)) >= 0) {
    135            endIndex = sb.indexOf("*/", startIndex + 2);
    136            if (endIndex < 0) {
    137                endIndex = totallen;
    138            }
    139
    140            token = sb.substring(startIndex + 2, endIndex);
    141            comments.add(token);
    142            sb.replace(startIndex + 2, endIndex, "___YUICSSMIN_PRESERVE_CANDIDATE_COMMENT_" + (comments.size() - 1) + "___");
    143            startIndex += 2;
    144        }
    145        css = sb.toString();
    146
    147        // preserve strings so their content doesn't get accidentally minified
    148        sb = new StringBuffer();
    149        p = Pattern.compile("(\"([^\\\\\"]|\\\\.|\\\\)*\")|(\'([^\\\\\']|\\\\.|\\\\)*\')");
    150        m = p.matcher(css);
    151        while (m.find()) {
    152            token = m.group();
    153            char quote = token.charAt(0);
    154            token = token.substring(1, token.length() - 1);
    155
    156            // maybe the string contains a comment-like substring?
    157            // one, maybe more? put'em back then
    158            if (token.indexOf("___YUICSSMIN_PRESERVE_CANDIDATE_COMMENT_") >= 0) {
    159                for (i = 0, max = comments.size(); i < max; i += 1) {
    160                    token = token.replace("___YUICSSMIN_PRESERVE_CANDIDATE_COMMENT_" + i + "___", comments.get(i).toString());
    161                }
    162            }
    163
    164            // minify alpha opacity in filter strings
    165            token = token.replaceAll("(?i)progid:DXImageTransform.Microsoft.Alpha\\(Opacity=", "alpha(opacity=");
    166
    167            preservedTokens.add(token);
    168            String preserver = quote + "___YUICSSMIN_PRESERVED_TOKEN_" + (preservedTokens.size() - 1) + "___" + quote;
    169            m.appendReplacement(sb, preserver);
    170        }
    171        m.appendTail(sb);
    172        css = sb.toString();
    173
    174
    175        // strings are safe, now wrestle the comments
    176        for (i = 0, max = comments.size(); i < max; i += 1) {
    177
    178            token = comments.get(i).toString();
    179            placeholder = "___YUICSSMIN_PRESERVE_CANDIDATE_COMMENT_" + i + "___";
    180
    181            // ! in the first position of the comment means preserve
    182            // so push to the preserved tokens while stripping the !
    183            if (token.startsWith("!")) {
    184                preservedTokens.add(token);
    185                css = css.replace(placeholder,  "___YUICSSMIN_PRESERVED_TOKEN_" + (preservedTokens.size() - 1) + "___");
    186                continue;
    187            }
    188
    189            // \ in the last position looks like hack for Mac/IE5
    190            // shorten that to /*\*/ and the next one to /**/
    191            if (token.endsWith("\\")) {
    192                preservedTokens.add("\\");
    193                css = css.replace(placeholder,  "___YUICSSMIN_PRESERVED_TOKEN_" + (preservedTokens.size() - 1) + "___");
    194                i = i + 1; // attn: advancing the loop
    195                preservedTokens.add("");
    196                css = css.replace("___YUICSSMIN_PRESERVE_CANDIDATE_COMMENT_" + i + "___",  "___YUICSSMIN_PRESERVED_TOKEN_" + (preservedTokens.size() - 1) + "___");
    197                continue;
    198            }
    199
    200            // keep empty comments after child selectors (IE7 hack)
    201            // e.g. html >/**/ body
    202            if (token.length() == 0) {
    203                startIndex = css.indexOf(placeholder);
    204                if (startIndex > 2) {
    205                    if (css.charAt(startIndex - 3) == '>') {
    206                        preservedTokens.add("");
    207                        css = css.replace(placeholder,  "___YUICSSMIN_PRESERVED_TOKEN_" + (preservedTokens.size() - 1) + "___");
    208                    }
    209                }
    210            }
    211
    212            // in all other cases kill the comment
    213            css = css.replace("/*" + placeholder + "*/", "");
    214        }
    215
    216
    217        // Normalize all whitespace strings to single spaces. Easier to work with that way.
    218        css = css.replaceAll("\\s+", " ");
    219
    220        css = this.preserveOldIESpecificMatrixDefinition(css, preservedTokens);
    221
    222        // Remove the spaces before the things that should not have spaces before them.
    223        // But, be careful not to turn "p :link {...}" into "p:link{...}"
    224        // Swap out any pseudo-class colons with the token, and then swap back.
    225        sb = new StringBuffer();
    226        p = Pattern.compile("(^|\\})(([^\\{:])+:)+([^\\{]*\\{)");
    227        m = p.matcher(css);
    228        while (m.find()) {
    229            String s = m.group();
    230            s = s.replaceAll(":", "___YUICSSMIN_PSEUDOCLASSCOLON___");
    231            s = s.replaceAll( "\\\\", "\\\\\\\\" ).replaceAll( "\\$", "\\\\\\$" );
    232            m.appendReplacement(sb, s);
    233        }
    234        m.appendTail(sb);
    235        css = sb.toString();
    236        // Remove spaces before the things that should not have spaces before them.
    237        css = css.replaceAll("\\s+([!{};:>+\\(\\)\\],])", "$1");
    238        // Restore spaces for !important
    239        css = css.replaceAll("!important", " !important");
    240        // bring back the colon
    241        css = css.replaceAll("___YUICSSMIN_PSEUDOCLASSCOLON___", ":");
    242
    243        // retain space for special IE6 cases
    244        sb = new StringBuffer();
    245        p = Pattern.compile("(?i):first\\-(line|letter)(\\{|,)");
    246        m = p.matcher(css);
    247        while (m.find()) {
    248            m.appendReplacement(sb, ":first-" + m.group(1).toLowerCase() + " " + m.group(2));
    249        }
    250        m.appendTail(sb);
    251        css = sb.toString();
    252
    253        // no space after the end of a preserved comment
    254        css = css.replaceAll("\\*/ ", "*/");
    255
    256        // If there are multiple @charset directives, push them to the top of the file.
    257        sb = new StringBuffer();
    258        p = Pattern.compile("(?i)^(.*)(@charset)( \"[^\"]*\";)");
    259        m = p.matcher(css);
    260        while (m.find()) {
    261            m.appendReplacement(sb, m.group(2).toLowerCase() + m.group(3) + m.group(1));
    262        }
    263        m.appendTail(sb);
    264        css = sb.toString();
    265
    266        // When all @charset are at the top, remove the second and after (as they are completely ignored).
    267        sb = new StringBuffer();
    268        p = Pattern.compile("(?i)^((\\s*)(@charset)( [^;]+;\\s*))+");
    269        m = p.matcher(css);
    270        while (m.find()) {
    271            m.appendReplacement(sb, m.group(2) + m.group(3).toLowerCase() + m.group(4));
    272        }
    273        m.appendTail(sb);
    274        css = sb.toString();
    275
    276        // lowercase some popular @directives (@charset is done right above)
    277        sb = new StringBuffer();
    278        p = Pattern.compile("(?i)@(font-face|import|(?:-(?:atsc|khtml|moz|ms|o|wap|webkit)-)?keyframe|media|page|namespace)");
    279        m = p.matcher(css);
    280        while (m.find()) {
    281            m.appendReplacement(sb, '@' + m.group(1).toLowerCase());
    282        }
    283        m.appendTail(sb);
    284        css = sb.toString();
    285
    286        // lowercase some more common pseudo-elements
    287        sb = new StringBuffer();
    288        p = Pattern.compile("(?i):(active|after|before|checked|disabled|empty|enabled|first-(?:child|of-type)|focus|hover|last-(?:child|of-type)|link|only-(?:child|of-type)|root|:selection|target|visited)");
    289        m = p.matcher(css);
    290        while (m.find()) {
    291            m.appendReplacement(sb, ':' + m.group(1).toLowerCase());
    292        }
    293        m.appendTail(sb);
    294        css = sb.toString();
    295
    296        // lowercase some more common functions
    297        sb = new StringBuffer();
    298        p = Pattern.compile("(?i):(lang|not|nth-child|nth-last-child|nth-last-of-type|nth-of-type|(?:-(?:moz|webkit)-)?any)\\(");
    299        m = p.matcher(css);
    300        while (m.find()) {
    301            m.appendReplacement(sb, ':' + m.group(1).toLowerCase() + '(');
    302        }
    303        m.appendTail(sb);
    304        css = sb.toString();
    305
    306        // lower case some common function that can be values
    307        // NOTE: rgb() isn't useful as we replace with #hex later, as well as and() is already done for us right after this
    308        sb = new StringBuffer();
    309        p = Pattern.compile("(?i)([:,\\( ]\\s*)(attr|color-stop|from|rgba|to|url|(?:-(?:atsc|khtml|moz|ms|o|wap|webkit)-)?(?:calc|max|min|(?:repeating-)?(?:linear|radial)-gradient)|-webkit-gradient)");
    310        m = p.matcher(css);
    311        while (m.find()) {
    312            m.appendReplacement(sb, m.group(1) + m.group(2).toLowerCase());
    313        }
    314        m.appendTail(sb);
    315        css = sb.toString();
    316
    317        // Put the space back in some cases, to support stuff like
    318        // @media screen and (-webkit-min-device-pixel-ratio:0){
    319        css = css.replaceAll("(?i)\\band\\(", "and (");
    320
    321        // Remove the spaces after the things that should not have spaces after them.
    322        css = css.replaceAll("([!{}:;>+\\(\\[,])\\s+", "$1");
    323
    324        // remove unnecessary semicolons
    325        css = css.replaceAll(";+}", "}");
    326
    327        // Replace 0(px,em,%) with 0.
    328        css = css.replaceAll("(?i)(^|[^0-9])(?:0?\\.)?0(?:px|em|%|in|cm|mm|pc|pt|ex|deg|g?rad|m?s|k?hz)", "$10");
    329
    330        // Replace 0 0 0 0; with 0.
    331        css = css.replaceAll(":0 0 0 0(;|})", ":0$1");
    332        css = css.replaceAll(":0 0 0(;|})", ":0$1");
    333        css = css.replaceAll(":0 0(;|})", ":0$1");
    334
    335
    336        // Replace background-position:0; with background-position:0 0;
    337        // same for transform-origin
    338        sb = new StringBuffer();
    339        p = Pattern.compile("(?i)(background-position|webkit-mask-position|transform-origin|webkit-transform-origin|moz-transform-origin|o-transform-origin|ms-transform-origin):0(;|})");
    340        m = p.matcher(css);
    341        while (m.find()) {
    342            m.appendReplacement(sb, m.group(1).toLowerCase() + ":0 0" + m.group(2));
    343        }
    344        m.appendTail(sb);
    345        css = sb.toString();
    346
    347        // Replace 0.6 to .6, but only when preceded by : or a white-space
    348        css = css.replaceAll("(:|\\s)0+\\.(\\d+)", "$1.$2");
    349
    350        // Shorten colors from rgb(51,102,153) to #336699
    351        // This makes it more likely that it'll get further compressed in the next step.
    352        p = Pattern.compile("rgb\\s*\\(\\s*([0-9,\\s]+)\\s*\\)");
    353        m = p.matcher(css);
    354        sb = new StringBuffer();
    355        while (m.find()) {
    356            String[] rgbcolors = m.group(1).split(",");
    357            StringBuffer hexcolor = new StringBuffer("#");
    358            for (i = 0; i < rgbcolors.length; i++) {
    359                int val = Integer.parseInt(rgbcolors[i]);
    360                if (val < 16) {
    361                    hexcolor.append('0');
    362                }
    363
    364                // If someone passes an RGB value that's too big to express in two characters, round down.
    365                // Probably should throw out a warning here, but generating valid CSS is a bigger concern.
    366                if (val > 255) {
    367                    val = 255;
    368                }
    369                hexcolor.append(Integer.toHexString(val));
    370            }
    371            m.appendReplacement(sb, hexcolor.toString());
    372        }
    373        m.appendTail(sb);
    374        css = sb.toString();
    375
    376        // Shorten colors from #AABBCC to #ABC. Note that we want to make sure
    377        // the color is not preceded by either ", " or =. Indeed, the property
    378        //     filter: chroma(color="#FFFFFF");
    379        // would become
    380        //     filter: chroma(color="#FFF");
    381        // which makes the filter break in IE.
    382        // We also want to make sure we're only compressing #AABBCC patterns inside { }, not id selectors ( #FAABAC {} )
    383        // We also want to avoid compressing invalid values (e.g. #AABBCCD to #ABCD)
    384        p = Pattern.compile("(\\=\\s*?[\"']?)?" + "#([0-9a-fA-F])([0-9a-fA-F])([0-9a-fA-F])([0-9a-fA-F])([0-9a-fA-F])([0-9a-fA-F])" + "(:?\\}|[^0-9a-fA-F{][^{]*?\\})");
    385
    386        m = p.matcher(css);
    387        sb = new StringBuffer();
    388        int index = 0;
    389
    390        while (m.find(index)) {
    391
    392            sb.append(css.substring(index, m.start()));
    393
    394            boolean isFilter = (m.group(1) != null && !"".equals(m.group(1)));
    395
    396            if (isFilter) {
    397                // Restore, as is. Compression will break filters
    398                sb.append(m.group(1) + "#" + m.group(2) + m.group(3) + m.group(4) + m.group(5) + m.group(6) + m.group(7));
    399            } else {
    400                if( m.group(2).equalsIgnoreCase(m.group(3)) &&
    401                        m.group(4).equalsIgnoreCase(m.group(5)) &&
    402                        m.group(6).equalsIgnoreCase(m.group(7))) {
    403
    404                    // #AABBCC pattern
    405                    sb.append("#" + (m.group(3) + m.group(5) + m.group(7)).toLowerCase());
    406
    407                } else {
    408
    409                    // Non-compressible color, restore, but lower case.
    410                    sb.append("#" + (m.group(2) + m.group(3) + m.group(4) + m.group(5) + m.group(6) + m.group(7)).toLowerCase());
    411                }
    412            }
    413
    414            index = m.end(7);
    415        }
    416
    417        sb.append(css.substring(index));
    418        css = sb.toString();
    419
    420        // Replace #f00 -> red
    421        css = css.replaceAll("(:|\\s)(#f00)(;|})", "$1red$3");
    422        // Replace other short color keywords
    423        css = css.replaceAll("(:|\\s)(#000080)(;|})", "$1navy$3");
    424        css = css.replaceAll("(:|\\s)(#808080)(;|})", "$1gray$3");
    425        css = css.replaceAll("(:|\\s)(#808000)(;|})", "$1olive$3");
    426        css = css.replaceAll("(:|\\s)(#800080)(;|})", "$1purple$3");
    427        css = css.replaceAll("(:|\\s)(#c0c0c0)(;|})", "$1silver$3");
    428        css = css.replaceAll("(:|\\s)(#008080)(;|})", "$1teal$3");
    429        css = css.replaceAll("(:|\\s)(#ffa500)(;|})", "$1orange$3");
    430        css = css.replaceAll("(:|\\s)(#800000)(;|})", "$1maroon$3");
    431
    432        // border: none -> border:0
    433        sb = new StringBuffer();
    434        p = Pattern.compile("(?i)(border|border-top|border-right|border-bottom|border-left|outline|background):none(;|})");
    435        m = p.matcher(css);
    436        while (m.find()) {
    437            m.appendReplacement(sb, m.group(1).toLowerCase() + ":0" + m.group(2));
    438        }
    439        m.appendTail(sb);
    440        css = sb.toString();
    441
    442        // shorter opacity IE filter
    443        css = css.replaceAll("(?i)progid:DXImageTransform.Microsoft.Alpha\\(Opacity=", "alpha(opacity=");
    444
    445        // Find a fraction that is used for Opera's -o-device-pixel-ratio query
    446        // Add token to add the "\" back in later
    447        css = css.replaceAll("\\(([\\-A-Za-z]+):([0-9]+)\\/([0-9]+)\\)", "($1:$2___YUI_QUERY_FRACTION___$3)");
    448
    449        // Remove empty rules.
    450        css = css.replaceAll("[^\\}\\{/;]+\\{\\}", "");
    451
    452        // Add "\" back to fix Opera -o-device-pixel-ratio query
    453        css = css.replaceAll("___YUI_QUERY_FRACTION___", "/");
    454
    455        // TODO: Should this be after we re-insert tokens. These could alter the break points. However then
    456        // we'd need to make sure we don't break in the middle of a string etc.
    457        if (linebreakpos >= 0) {
    458            // Some source control tools don't like it when files containing lines longer
    459            // than, say 8000 characters, are checked in. The linebreak option is used in
    460            // that case to split long lines after a specific column.
    461            i = 0;
    462            int linestartpos = 0;
    463            sb = new StringBuffer(css);
    464            while (i < sb.length()) {
    465                char c = sb.charAt(i++);
    466                if (c == '}' && i - linestartpos > linebreakpos) {
    467                    sb.insert(i, '\n');
    468                    linestartpos = i;
    469                }
    470            }
    471
    472            css = sb.toString();
    473        }
    474
    475        // Replace multiple semi-colons in a row by a single one
    476        // See SF bug #1980989
    477        css = css.replaceAll(";;+", ";");
    478
    479        // restore preserved comments and strings
    480        for(i = preservedTokens.size() - 1; i >= 0 ; i--) {
    481            css = css.replace("___YUICSSMIN_PRESERVED_TOKEN_" + i + "___", preservedTokens.get(i).toString());
    482        }
    483
    484        // Trim the final string (for any leading or trailing white spaces)
    485        css = css.trim();
    486
    487        // Write the output...
    488        out.write(css);
    489    }
    490}