// Copyright (C) 2006 Google Inc.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//      http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.


/**
 * @fileoverview
 * some functions for browser-side pretty printing of code contained in html.
 *
 * The lexer should work on a number of languages including C and friends,
 * Java, Python, Bash, SQL, HTML, XML, CSS, Javascript, and Makefiles.
 * It works passably on Ruby, PHP and Awk and a decent subset of Perl, but,
 * because of commenting conventions, doesn't work on Smalltalk, Lisp-like, or
 * CAML-like languages.
 *
 * If there's a language not mentioned here, then I don't know it, and don't
 * know whether it works.  If it has a C-like, Bash-like, or XML-like syntax
 * then it should work passably.
 *
 * Usage:
 * 1) include this source file in an html page via
 * <script type="text/javascript" src="/path/to/prettify.js"></script>
 * 2) define style rules.  See the example page for examples.
 * 3) mark the <pre> and <code> tags in your source with class=prettyprint.
 *    You can also use the (html deprecated) <xmp> tag, but the pretty printer
 *    needs to do more substantial DOM manipulations to support that, so some
 *    css styles may not be preserved.
 * That's it.  I wanted to keep the API as simple as possible, so there's no
 * need to specify which language the code is in.
 *
 * Change log:
 * cbeust, 2006/08/22
 *   Java annotations (start with "@") are now captured as literals ("lit")
 */

var PR_keywords = {};
/** initialize the keyword list for our target languages. */
(function () {
  var CPP_KEYWORDS = "abstract bool break case catch char class const " +
    "const_cast continue default delete deprecated dllexport dllimport do " +
    "double dynamic_cast else enum explicit extern false float for friend " +
    "goto if inline int long mutable naked namespace new noinline noreturn " +
    "nothrow novtable operator private property protected public register " +
    "reinterpret_cast return selectany short signed sizeof static " +
    "static_cast struct switch template this thread throw true try typedef " +
    "typeid typename union unsigned using declaration, directive uuid " +
    "virtual void volatile while typeof";
  var CSHARP_KEYWORDS = "as base by byte checked decimal delegate descending " +
    "event finally fixed foreach from group implicit in interface internal " +
    "into is lock null object out override orderby params readonly ref sbyte " +
    "sealed stackalloc string select uint ulong unchecked unsafe ushort var";
  var JAVA_KEYWORDS = "package synchronized boolean implements import throws " +
    "instanceof transient extends final strictfp native super";
  var JSCRIPT_KEYWORDS = "debugger export function with NaN Infinity";
  var PERL_KEYWORDS = "require sub unless until use elsif BEGIN END";
  var PYTHON_KEYWORDS = "and assert def del elif except exec global lambda " +
    "not or pass print raise yield False True None";
  var RUBY_KEYWORDS = "then end begin rescue ensure module when undef next " +
    "redo retry alias defined";
  var SH_KEYWORDS = "done fi";

  var KEYWORDS = [CPP_KEYWORDS, CSHARP_KEYWORDS, JAVA_KEYWORDS,
                  JSCRIPT_KEYWORDS, PERL_KEYWORDS, PYTHON_KEYWORDS,
                  RUBY_KEYWORDS, SH_KEYWORDS];
  for (var k = 0; k < KEYWORDS.length; k++) {
    var kw = KEYWORDS[k].split(' ');
    for (var i = 0; i < kw.length; i++) {
      if (kw[i]) { PR_keywords[kw[i]] = true; }
    }
  }
}).call(this);

// token style names.  correspond to css classes
/** token style for a string literal */
var PR_STRING = 'str';
/** token style for a keyword */
var PR_KEYWORD = 'kwd';
/** token style for a comment */
var PR_COMMENT = 'com';
/** token style for a type */
var PR_TYPE = 'typ';
/** token style for a literal value.  e.g. 1, null, true. */
var PR_LITERAL = 'lit';
/** token style for a punctuation string. */
var PR_PUNCTUATION = 'pun';
/** token style for a punctuation string. */
var PR_PLAIN = 'pln';

/** token style for an sgml tag. */
var PR_TAG = 'tag';
/** token style for a markup declaration such as a DOCTYPE. */
var PR_DECLARATION = 'dec';
/** token style for embedded source. */
var PR_SOURCE = 'src';
/** token style for an sgml attribute name. */
var PR_ATTRIB_NAME = 'atn';
/** token style for an sgml attribute value. */
var PR_ATTRIB_VALUE = 'atv';

/** the number of characters between tab columns */
var PR_TAB_WIDTH = 8;

// some string utilities
function PR_isWordChar(ch) {
  return (ch >= 'a' && ch <= 'z') || (ch >= 'A' && ch <= 'Z');
}

/** Splice one array into another.
  * Like the python <code>
  * container[containerPosition:containerPosition + countReplaced] = inserted
  * </code>
  * @param {Array} inserted
  * @param {Array} container modified in place
  * @param {Number} containerPosition
  * @param {Number} countReplaced
  */
function PR_spliceArrayInto(
    inserted, container, containerPosition, countReplaced) {
  inserted.unshift(containerPosition, countReplaced || 0);
  try {
    container.splice.apply(container, inserted);
  } finally {
    inserted.splice(0, 2);
  }
}

/** a set of tokens that can precede a regular expression literal in javascript.
  * http://www.mozilla.org/js/language/js20/rationale/syntax.html has the full
  * list, but I've removed ones that might be problematic when seen in languages
  * that don't support regular expression literals.
  *
  * <p>Specifically, I've removed any keywords that can't precede a regexp
  * literal in a syntactically legal javascript program, and I've removed the
  * "in" keyword since it's not a keyword in many languages, and might be used
  * as a count of inches.
  * @private
  */
var REGEXP_PRECEDER_PATTERN = (function () {
    var preceders = [
        "!", "!=", "!==", "#", "%", "%=", "&", "&&", "&&=",
        "&=", "(", "*", "*=", /* "+", */ "+=", ",", /* "-", */ "-=",
        "->", /*".", "..", "...", handled below */ "/", "/=", ":", "::", ";",
        "<", "<<", "<<=", "<=", "=", "==", "===", ">",
        ">=", ">>", ">>=", ">>>", ">>>=", "?", "@", "[",
        "^", "^=", "^^", "^^=", "{", "|", "|=", "||",
        "||=", "~", "break", "case", "continue", "delete",
        "do", "else", "finally", "instanceof",
        "return", "throw", "try", "typeof"
        ];
    var pattern = '(?:' +
      '(?:(?:^|[^0-9\.])\\.{1,3})|' +  // a dot that's not part of a number
      '(?:(?:^|[^\\+])\\+)|' +  // allow + but not ++
      '(?:(?:^|[^\\-])-)'  // allow - but not --
      ;
    for (var i = 0; i < preceders.length; ++i) {
      var preceder = preceders[i];
      if (PR_isWordChar(preceder.charAt(0))) {
        pattern += '|\\b' + preceder;
      } else {
        pattern += '|' + preceder.replace(/([^=<>:&])/g, '\\$1');
      }
    }
    pattern += '|^)\\s*$';  // matches at end, and matches empty string
    return new RegExp(pattern);
    // CAVEAT: this does not properly handle the case where a regular expression
    // immediately follows another since a regular expression may have flags
    // for case-sensitivity and the like.  Having regexp tokens adjacent is not
    // valid in any language I'm aware of, so I'm punting.
    // TODO: maybe style special characters inside a regexp as punctuation.
  })();

// Define regexps here so that the interpreter doesn't have to create an object
// each time the function containing them is called.
// The language spec requires a new object created even if you don't access the
// $1 members.
var pr_amp = /&/g;
var pr_lt = /</g;
var pr_gt = />/g;
var pr_quot = /\"/g;
/** like textToHtml but escapes double quotes to be attribute safe. */
function PR_attribToHtml(str) {
  return str.replace(pr_amp, '&amp;')
    .replace(pr_lt, '&lt;')
    .replace(pr_gt, '&gt;')
    .replace(pr_quot, '&quot;');
}

/** escapest html special characters to html. */
function PR_textToHtml(str) {
  return str.replace(pr_amp, '&amp;')
    .replace(pr_lt, '&lt;')
    .replace(pr_gt, '&gt;');
}


var pr_ltEnt = /&lt;/g;
var pr_gtEnt = /&gt;/g;
var pr_aposEnt = /&apos;/g;
var pr_quotEnt = /&quot;/g;
var pr_ampEnt = /&amp;/g;
/** unescapes html to plain text. */
function PR_htmlToText(html) {
  var pos = html.indexOf('&');
  if (pos < 0) { return html; }
  // Handle numeric entities specially.  We can't use functional substitution
  // since that doesn't work in older versions of Safari.
  // These should be rare since most browsers convert them to normal chars.
  for (--pos; (pos = html.indexOf('&#', pos + 1)) >= 0;) {
    var end = html.indexOf(';', pos);
    if (end >= 0) {
      var num = html.substring(pos + 3, end);
      var radix = 10;
      if (num && num.charAt(0) == 'x') {
        num = num.substring(1);
        radix = 16;
      }
      var codePoint = parseInt(num, radix);
      if (!isNaN(codePoint)) {
        html = (html.substring(0, pos) + String.fromCharCode(codePoint) +
                html.substring(end + 1));
      }
    }
  }

  return html.replace(pr_ltEnt, '<')
    .replace(pr_gtEnt, '>')
    .replace(pr_aposEnt, "'")
    .replace(pr_quotEnt, '"')
    .replace(pr_ampEnt, '&');
}

/** is the given node's innerHTML normally unescaped? */
function PR_isRawContent(node) {
  return 'XMP' == node.tagName;
}

var PR_innerHtmlWorks = null;
function PR_getInnerHtml(node) {
  // inner html is hopelessly broken in Safari 2.0.4 when the content is
  // an html description of well formed XML and the containing tag is a PRE
  // tag, so we detect that case and emulate innerHTML.
  if (null === PR_innerHtmlWorks) {
    var testNode = document.createElement('PRE');
    testNode.appendChild(
        document.createTextNode('<!DOCTYPE foo PUBLIC "foo bar">\n<foo />'));
    PR_innerHtmlWorks = !/</.test(testNode.innerHTML);
  }

  if (PR_innerHtmlWorks) {
    var content = node.innerHTML;
    // XMP tags contain unescaped entities so require special handling.
    if (PR_isRawContent(node)) {
      content = PR_textToHtml(content);
    }
    return content;
  }

  var out = [];
  for (var child = node.firstChild; child; child = child.nextSibling) {
    PR_normalizedHtml(child, out);
  }
  return out.join('');
}

/** walks the DOM returning a properly escaped version of innerHTML.
  */
function PR_normalizedHtml(node, out) {
  switch (node.nodeType) {
    case 1:  // an element
      var name = node.tagName.toLowerCase();
      out.push('\074', name);
      for (var i = 0; i < node.attributes.length; ++i) {
        var attr = node.attributes[i];
        if (!attr.specified) { continue; }
        out.push(' ');
        PR_normalizedHtml(attr, out);
      }
      out.push('>');
      for (var child = node.firstChild; child; child = child.nextSibling) {
        PR_normalizedHtml(child, out);
      }
      if (node.firstChild || !/^(?:br|link|img)$/.test(name)) {
        out.push('<\/', name, '>');
      }
      break;
    case 2: // an attribute
      out.push(node.name.toLowerCase(), '="', PR_attribToHtml(node.value), '"');
      break;
    case 3: case 4: // text
      out.push(PR_textToHtml(node.nodeValue));
      break;
  }
}

/** returns a function that expand tabs to spaces.  This function can be fed
  * successive chunks of text, and will maintain its own internal state to
  * keep track of how tabs are expanded.
  * @return {function (plainText : String) : String } a function that takes
  *   plain text and return the text with tabs expanded.
  * @private
  */
function PR_tabExpander(tabWidth) {
  var SPACES = '                ';
  var charInLine = 0;

  return function (plainText) {
    // walk over each character looking for tabs and newlines.
    // On tabs, expand them.  On newlines, reset charInLine.
    // Otherwise increment charInLine
    var out = null;
    var pos = 0;
    for (var i = 0, n = plainText.length; i < n; ++i) {
      var ch = plainText.charAt(i);

      switch (ch) {
        case '\t':
          if (!out) { out = []; }
          out.push(plainText.substring(pos, i));
          // calculate how much space we need in front of this part
          // nSpaces is the amount of padding -- the number of spaces needed to
          // move us to the next column, where columns occur at factors of
          // tabWidth.
          var nSpaces = tabWidth - (charInLine % tabWidth);
          charInLine += nSpaces;
          for (; nSpaces >= 0; nSpaces -= SPACES.length) {
            out.push(SPACES.substring(0, nSpaces));
          }
          pos = i + 1;
          break;
        case '\n':
          charInLine = 0;
          break;
        default:
          ++charInLine;
      }
    }
    if (!out) { return plainText; }
    out.push(plainText.substring(pos));
    return out.join('');
  };
}

// The below pattern matches one of the following
// (1) /[^<]+/ : A run of characters other than '<'
// (2) /<!--.*?-->/: an HTML comment
// (3) /<!\[CDATA\[.*?\]\]>/: a cdata section
// (3) /<\/?[a-zA-Z][^>]*>/ : A probably tag that should not be highlighted
// (4) /</ : A '<' that does not begin a larger chunk.  Treated as 1
var pr_chunkPattern =
  /(?:[^<]+|<!--[\s\S]*?-->|<!\[CDATA\[([\s\S]*?)\]\]>|<\/?[a-zA-Z][^>]*>|<)/g;
var pr_commentPrefix = /^<!--/;
var pr_cdataPrefix = /^<\[CDATA\[/;
var pr_brPrefix = /^<br\b/i;

/** split markup into chunks of html tags (style null) and
  * plain text (style {@link #PR_PLAIN}), converting tags which are significant
  * for tokenization (<br>) into their textual equivalent.
  *
  * @param {String} s html where whitespace is considered significant.
  * @return {Object} source code and extracted tags.
  * @private
  */
function PR_extractTags(s) {

  // since the pattern has the 'g' modifier and defines no capturing groups,
  // this will return a list of all chunks which we then classify and wrap as
  // PR_Tokens
  var matches = s.match(pr_chunkPattern);
  var sourceBuf = [];
  var sourceBufLen = 0;
  var extractedTags = [];
  if (matches) {
    for (var i = 0, n = matches.length; i < n; ++i) {
      var match = matches[i];
      if (match.length > 1 && match.charAt(0) === '<') {
        if (pr_commentPrefix.test(match)) { continue; }
        if (pr_cdataPrefix.test(match)) {
          // strip CDATA prefix and suffix.  Don't unescape since it's CDATA
          sourceBuf.push(match.substring(9, match.length - 3));
          sourceBufLen += match.length - 12;
        } else if (pr_brPrefix.test(match)) {
          // <br> tags are lexically significant so convert them to text.
          // This is undone later.
          // <br> tags are lexically significant 
          sourceBuf.push('\n');
          sourceBufLen += 1;
        } else {
          extractedTags.push(sourceBufLen, match);
        }
      } else {
        var literalText = PR_htmlToText(match);
        sourceBuf.push(literalText);
        sourceBufLen += literalText.length;
      }
    }
  }
  return { source: sourceBuf.join(''), tags: extractedTags };
}

/** Given triples of [style, pattern, context] returns a lexing function,
  * The lexing function interprets the patterns to find token boundaries and
  * returns a decoration list of the form
  * [index_0, style_0, index_1, style_1, ..., index_n, style_n]
  * where index_n is an index into the sourceCode, and style_n is a style
  * constant like PR_PLAIN.  index_n-1 <= index_n, and style_n-1 applies to
  * all characters in sourceCode[index_n-1:index_n].
  *
  * The stylePatterns is a list whose elements have the form
  * [style : String, pattern : RegExp, context : RegExp, shortcut : String].
  &
  * Style is a style constant like PR_PLAIN.
  *
  * Pattern must only match prefixes, and if it matches a prefix and context is
  * null or matches the last non-comment token parsed, then that match is
  * considered a token with the same style.
  *
  * Context is applied to the last non-whitespace, non-comment token recognized.
  *
  * Shortcut is an optional string of characters, any of which, if the first
  * character, gurantee that this pattern and only this pattern matches.
  *
  * @param {Array} shortcutStylePatterns patterns that always start with
  *   a known character.  Must have a shortcut string.
  * @param {Array} fallthroughStylePatterns patterns that will be tried in order
  *   if the shortcut ones fail.  May have shortcuts.
  *
  * @return {function (sourceCode : String) -> Array.<Number|String>} a function
  *   that takes source code and a list of decorations to append to.
  */
function PR_createSimpleLexer(shortcutStylePatterns,
                              fallthroughStylePatterns) {
  var shortcuts = {};
  (function () {
    var allPatterns = shortcutStylePatterns.concat(fallthroughStylePatterns);
    for (var i = allPatterns.length; --i >= 0;) {
      var patternParts = allPatterns[i];
      var shortcutChars = patternParts[3];
      if (shortcutChars) {
        for (var c = shortcutChars.length; --c >= 0;) {
          shortcuts[shortcutChars.charAt(c)] = patternParts;
        }
      }
    }
  })();

  var nPatterns = fallthroughStylePatterns.length;

  return function (sourceCode, opt_basePos) {
    opt_basePos = opt_basePos || 0;
    var decorations = [opt_basePos, PR_PLAIN];
    var lastToken = '';
    var pos = 0;  // index into sourceCode
    var tail = sourceCode;

    while (tail.length) {
      var style;
      var token = null;

      var patternParts = shortcuts[tail.charAt(0)];
      if (patternParts) {
        var match = tail.match(patternParts[1]);
        token = match[0];
        style = patternParts[0];
      } else {
        for (var i = 0; i < nPatterns; ++i) {
          patternParts = fallthroughStylePatterns[i];
          var contextPattern = patternParts[2];
          if (contextPattern && !contextPattern.test(lastToken)) {
            // rule can't be used
            continue;
          }
          var match = tail.match(patternParts[1]);
          if (match) {
            token = match[0];
            style = patternParts[0];
            break;
          }
        }

        if (!token) {  // make sure that we make progress
          style = PR_PLAIN;
          token = tail.substring(0, 1);
        }
      }

      decorations.push(opt_basePos + pos, style);
      pos += token.length;
      tail = tail.substring(token.length);
      if (style !== PR_COMMENT && /\S/.test(token)) { lastToken = token; }
    }
    return decorations;
  };
}

var PR_C_STYLE_STRING_AND_COMMENT_LEXER = PR_createSimpleLexer([
    [PR_STRING,  /^\'(?:[^\\\']|\\[\s\S])*(?:\'|$)/, null, "'"],
    [PR_STRING,  /^\"(?:[^\\\"]|\\[\s\S])*(?:\"|$)/, null, '"'],
    [PR_STRING,  /^\`(?:[^\\\`]|\\[\s\S])*(?:\`|$)/, null, '`']
    ], [
    [PR_PLAIN,   /^(?:[^\'\"\`\/\#]+)/, null, ' \r\n'],
    [PR_COMMENT, /^#[^\r\n]*/, null, '#'],
    [PR_COMMENT, /^\/\/[^\r\n]*/, null],
    [PR_STRING,  /^\/(?:[^\\\*\/]|\\[\s\S])+(?:\/|$)/, REGEXP_PRECEDER_PATTERN],
    [PR_COMMENT, /^\/\*[\s\S]*?(?:\*\/|$)/, null]
    ]);
/** splits the given string into comment, string, and "other" tokens.
  * @param {String} sourceCode as plain text
  * @return {Array.<Number|String>} a decoration list.
  * @private
  */
function PR_splitStringAndCommentTokens(sourceCode) {
  return PR_C_STYLE_STRING_AND_COMMENT_LEXER(sourceCode);
}

var PR_C_STYLE_LITERAL_IDENTIFIER_PUNC_RECOGNIZER = PR_createSimpleLexer([], [
    [PR_PLAIN,       /^\s+/, null, ' \r\n'],
    // TODO(mikesamuel): recognize non-latin letters and numerals in identifiers
    [PR_PLAIN,       /^[a-z_$@][a-z_$@0-9]*/i, null],
    // A hex number
    [PR_LITERAL,     /^0x[a-f0-9]+[a-z]/i, null],
    // An octal or decimal number, possibly in scientific notation
    [PR_LITERAL,     /^(?:\d(?:_\d+)*\d*(?:\.\d*)?|\.\d+)(?:e[+-]?\d+)?[a-z]*/i,
     null, '123456789'],
    [PR_PUNCTUATION, /^[^\s\w\.$@]+/, null]
    // Fallback will handle decimal points not adjacent to a digit
    ]);
    
/** splits plain text tokens into more specific tokens, and then tries to
  * recognize keywords, and types.
  * @private
  */
function PR_splitNonStringNonCommentTokens(source, decorations) {
  for (var i = 0; i < decorations.length; i += 2) {
    var style = decorations[i + 1];
    if (style === PR_PLAIN) {
      var start = decorations[i];
      var end = i + 2 < decorations.length ? decorations[i + 2] : source.length;
      var chunk = source.substring(start, end);
      var subDecs = PR_C_STYLE_LITERAL_IDENTIFIER_PUNC_RECOGNIZER(chunk, start);
      for (var j = 0, m = subDecs.length; j < m; j += 2) {
        var subStyle = subDecs[j + 1];
        if (subStyle === PR_PLAIN) {
          var subStart = subDecs[j];
          var subEnd = j + 2 < m ? subDecs[j + 2] : chunk.length;
          var token = source.substring(subStart, subEnd);
          if (token == '.') {
            subDecs[j + 1] = PR_PUNCTUATION;
          } else if (token in PR_keywords) {
            subDecs[j + 1] = PR_KEYWORD;
          } else if (/^@?[A-Z][A-Z$]*[a-z][A-Za-z$]*$/.test(token)) {
            // classify types and annotations using Java's style conventions
            subDecs[j + 1] = token.charAt(0) == '@' ? PR_LITERAL : PR_TYPE;
          }
        }
      }
      PR_spliceArrayInto(subDecs, decorations, i, 2);
      i += subDecs.length - 2;
    }
  }
  return decorations;
}

var PR_MARKUP_LEXER = PR_createSimpleLexer([], [
    [PR_PLAIN,       /^[^<]+/, null],
    [PR_DECLARATION, /^<!\w[^>]*(?:>|$)/, null],
    [PR_COMMENT,     /^<!--[\s\S]*?(?:-->|$)/, null],
    [PR_SOURCE,      /^<\?[\s\S]*?(?:\?>|$)/, null],
    [PR_SOURCE,      /^<%[\s\S]*?(?:%>|$)/, null],
    [PR_SOURCE,
     // Tags whose content is not escaped, and which contain source code.
     /^<(script|style|xmp)\b[^>]*>[\s\S]*?<\/\1\b[^>]*>/i, null],
    [PR_TAG,         /^<\/?\w[^<>]*>/, null]
    ]);
// Splits any of the source|style|xmp entries above into a start tag,
// source content, and end tag.
var PR_SOURCE_CHUNK_PARTS = /^(<[^>]*>)([\s\S]*)(<\/[^>]*>)$/;
/** split markup on tags, comments, application directives, and other top level
  * constructs.  Tags are returned as a single token - attributes are not yet
  * broken out.
  * @private
  */
function PR_tokenizeMarkup(source) {
  var decorations = PR_MARKUP_LEXER(source);
  for (var i = 0; i < decorations.length; i += 2) {
    if (decorations[i + 1] === PR_SOURCE) {
      var start = decorations[i];
      var end = i + 2 < decorations.length ? decorations[i + 2] : source.length;
      // Split out start and end script tags as actual tags, and leave the body
      // with style SCRIPT.
      var sourceChunk = source.substring(start, end);
      var match = (sourceChunk.match(PR_SOURCE_CHUNK_PARTS)
                   //|| sourceChunk.match(/^(<[?%])([\s\S]*)([?%]>)$/)
                   );
      if (match) {
        decorations.splice(
            i, 2,
            start, PR_TAG,  // the open chunk
            start + match[1].length, PR_SOURCE,
            start + match[1].length + (match[2] || '').length, PR_TAG);
      }
    }
  }
  return decorations;
}

var PR_TAG_LEXER = PR_createSimpleLexer([
    [PR_ATTRIB_VALUE, /^\'[^\']*(?:\'|$)/, null, "'"],
    [PR_ATTRIB_VALUE, /^\"[^\"]*(?:\"|$)/, null, '"'],
    [PR_PUNCTUATION,  /^[<>\/=]+/, null, '<>/=']
    ], [
    [PR_TAG,          /^[\w-]+/, /^</],
    [PR_ATTRIB_VALUE, /^[\w-]+/, /^=/], 
    [PR_ATTRIB_NAME,  /^[\w-]+/, null], 
    [PR_PLAIN,        /^\s+/, null, ' \r\n']
    ]);
/** split tags attributes and their values out from the tag name, and
  * recursively lex source chunks.
  * @private
  */
function PR_splitTagAttributes(source, decorations) {
  for (var i = 0; i < decorations.length; i += 2) {
    var style = decorations[i + 1];
    if (style === PR_TAG) {
      var start = decorations[i];
      var end = i + 2 < decorations.length ? decorations[i + 2] : source.length;
      var chunk = source.substring(start, end);
      var subDecorations = PR_TAG_LEXER(chunk, start);
      PR_spliceArrayInto(subDecorations, decorations, i, 2);
      i += subDecorations.length - 2;
    }
  }
  return decorations;
}

/** identify regions of markup that are really source code, and recursivley
  * lex them.
  * @private
  */
function PR_splitSourceNodes(source, decorations) {
  for (var i = 0; i < decorations.length; i += 2) {
    var style = decorations[i + 1];
    if (style == PR_SOURCE) {
      // Recurse using the non-markup lexer
      var start = decorations[i];
      var end = i + 2 < decorations.length ? decorations[i + 2] : source.length;
      var subDecorations = PR_decorateSource(source.substring(start, end));
      for (var j = 0, m = subDecorations.length; j < m; j += 2) {
        subDecorations[j] += start;
      }
      PR_spliceArrayInto(subDecorations, decorations, i, 2);
      i += subDecorations.length - 2;
    }
  }
  return decorations;
}

/** identify attribute values that really contain source code and recursively
  * lex them.
  * @private
  */
function PR_splitSourceAttributes(source, decorations) {
  var nextValueIsSource = false;
  for (var i = 0; i < decorations.length; i += 2) {
    var style = decorations[i + 1];
    if (style === PR_ATTRIB_NAME) {
      var start = decorations[i];
      var end = i + 2 < decorations.length ? decorations[i + 2] : source.length;
      nextValueIsSource = /^on|^style$/i.test(source.substring(start, end));
    } else if (style == PR_ATTRIB_VALUE) {
      if (nextValueIsSource) {
        var start = decorations[i];
        var end
            = i + 2 < decorations.length ? decorations[i + 2] : source.length;
        var attribValue = source.substring(start, end);
        var attribLen = attribValue.length;
        var quoted =
            (attribLen >= 2 && /^[\"\']/.test(attribValue) &&
             attribValue.charAt(0) === attribValue.charAt(attribLen - 1));

        var attribSource;
        var attribSourceStart;
        var attribSourceEnd;
        if (quoted) {
          attribSourceStart = start + 1;
          attribSourceEnd = end - 1;
          attribSource = attribValue;
        } else {
          attribSourceStart = start + 1;
          attribSourceEnd = end - 1;
          attribSource = attribValue.substring(1, attribValue.length - 1);
        }

        var attribSourceDecorations = PR_decorateSource(attribSource);
        for (var j = 0, m = attribSourceDecorations.length; j < m; j += 2) {
          attribSourceDecorations[j] += attribSourceStart;
        }

        if (quoted) {
          attribSourceDecorations.push(attribSourceEnd, PR_ATTRIB_VALUE);
          PR_spliceArrayInto(attribSourceDecorations, decorations, i + 2, 0);
        } else {
          PR_spliceArrayInto(attribSourceDecorations, decorations, i, 2);
        }
      }
      nextValueIsSource = false;
    }
  }
  return decorations;
}

/** returns a list of decorations, where even entries
  *
  * This code treats ", ', and ` as string delimiters, and \ as a string escape.
  * It does not recognize perl's qq() style strings.  It has no special handling
  * for double delimiter escapes as in basic, or tje tripled delimiters used in
  * python, but should work on those regardless although in those cases a single
  * string literal may be broken up into multiple adjacent string literals.
  *
  * It recognizes C, C++, and shell style comments.
  *
  * @param {String} sourceCode as plain text
  * @return {Array.<String,Number>} a  decoration list
  */
function PR_decorateSource(sourceCode) {
  // Split into strings, comments, and other.
  // We do this because strings and comments are easily recognizable and can
  // contain stuff that looks like other tokens, so we want to mark those early
  // so we don't recurse into them.
  var decorations = PR_splitStringAndCommentTokens(sourceCode);
  
  // Split non comment|string tokens on whitespace and word boundaries
  decorations = PR_splitNonStringNonCommentTokens(sourceCode, decorations);
  
  return decorations;
}

/** returns a decoration list given a string of markup.
  *
  * This code recognizes a number of constructs.
  * <!-- ... --> comment
  * <!\w ... >   declaration
  * <\w ... >    tag
  * </\w ... >   tag
  * <?...?>      embedded source
  * <%...%>      embedded source
  * &[#\w]...;   entity
  *
  * It does not recognizes %foo; doctype entities from  .
  *
  * It will recurse into any <style>, <script>, and on* attributes using
  * PR_lexSource.
  */
function PR_decorateMarkup(sourceCode) {
  // This function works as follows:
  // 1) Start by splitting the markup into text and tag chunks
  //    Input:  String s
  //    Output: List<PR_Token> where style in (PR_PLAIN, null)
  // 2) Then split the text chunks further into comments, declarations,
  //    tags, etc.
  //    After each split, consider whether the token is the start of an
  //    embedded source section, i.e. is an open <script> tag.  If it is,
  //    find the corresponding close token, and don't bother to lex in between.
  //    Input:  List<String>
  //    Output: List<PR_Token> with style in (PR_TAG, PR_PLAIN, PR_SOURCE, null)
  // 3) Finally go over each tag token and split out attribute names and values.
  //    Input:  List<PR_Token>
  //    Output: List<PR_Token> where style in
  //            (PR_TAG, PR_PLAIN, PR_SOURCE, NAME, VALUE, null)
  var decorations = PR_tokenizeMarkup(sourceCode);
  decorations = PR_splitTagAttributes(sourceCode, decorations);
  decorations = PR_splitSourceNodes(sourceCode, decorations);
  decorations = PR_splitSourceAttributes(sourceCode, decorations);
  return decorations;
}

/**
  * @param {String} sourceText plain text
  * @param {Array.<Number|String>} extractedTags chunks of raw html preceded by
  *   their position in sourceText in order.
  * @param {Array.<Number|String> decorations style classes preceded by their
  *   position in sourceText in order.
  * @return {String} html
  * @private
  */
function PR_recombineTagsAndDecorations(
    sourceText, extractedTags, decorations) {
  var html = [];
  var outputIdx = 0;  // index past the last char in sourceText written to html

  var openDecoration = null;
  var currentDecoration = null;
  var tagPos = 0;  // index into extractedTags
  var decPos = 0;  // index into decorations
  var tabExpander = PR_tabExpander(PR_TAB_WIDTH);

  // A helper function that is responsible for opening sections of decoration
  // and outputing properly escaped chunks of source
  function emitTextUpTo(sourceIdx) {
    if (sourceIdx > outputIdx) {
      if (openDecoration && openDecoration !== currentDecoration) {
        // Close the current decoration
        html.push('</span>');
        openDecoration = null;
      }
      if (!openDecoration && currentDecoration) {
        openDecoration = currentDecoration;
        html.push('<span class="', openDecoration, '">');
      }
      // This interacts badly with some wikis which introduces paragraph tags
      // into pre blocks for some strange reason.
      // It's necessary for IE though which seems to lose the preformattednes

      // of <pre> tags when their innerHTML is assigned.
      // http://stud3.tuwien.ac.at/~e0226430/innerHtmlQuirk.html
      // and it serves to undo the conversion of <br>s to newlines done in
      // chunkify.
      var htmlChunk = PR_textToHtml(
          tabExpander(sourceText.substring(outputIdx, sourceIdx)))
          //.replace(/(\r\n?|\n| ) /g, '$1&nbsp;')
          .replace(/\r\n?|\n/g, '<br>');
      html.push(htmlChunk);
      outputIdx = sourceIdx;
    }
  }

  while (true) {
    // Determine if we're going to consume a tag this time around.  Otherwise we
    // consume a decoration or exit.
    var outputTag;
    if (tagPos < extractedTags.length) {
      if (decPos < decorations.length) {
        // Pick one giving preference to extractedTags since we shouldn't open
        // a new style that we're going to have to immediately close in order
        // to output a tag.
        outputTag = extractedTags[tagPos] <= decorations[decPos];
      } else {
        outputTag = true;
      }
    } else {
      outputTag = false;
    }
    // Consume either a decoration or a tag or exit.
    if (outputTag) {
      emitTextUpTo(extractedTags[tagPos]);
      if (openDecoration) {
        // Close the current decoration
        html.push('</span>');
        openDecoration = null;
      } 
      html.push(extractedTags[tagPos + 1]);
      tagPos += 2;
    } else if (decPos < decorations.length) {
      emitTextUpTo(decorations[decPos]);
      currentDecoration = decorations[decPos + 1];
      decPos += 2;
    } else {
      break;
    }
  }
  emitTextUpTo(sourceText.length);
  if (openDecoration) {
    html.push('</span>');
  }

  return html.join('');
}

/** pretty print a chunk of code.
  *
  * @param {String} sourceCodeHtml code as html
  * @return {String} code as html, but prettier
  */
function prettyPrintOne(sourceCodeHtml) {
  try {
    // Extract tags, and convert the source code to plain text.
    var sourceAndExtractedTags = PR_extractTags(sourceCodeHtml);
    /** Plain text. @type {String} */
    var source = sourceAndExtractedTags.source;

    /** Even entries are positions in source in ascending order.  Odd entries
      * are tags that were extracted at that position.
      * @type {Array.<Number|String>}
      */
    var extractedTags = sourceAndExtractedTags.tags;

    // Pick a lexer and apply it.
    /** Treat it as markup if the first non whitespace character is a < and the
      * last non-whitespace character is a >.
      * @type {Boolean}
      */
    var isMarkup = /^\s*</.test(source) && />\s*$/.test(source);

    /** Even entires are positions in source in ascending order.  Odd enties are
      * style markers (e.g., PR_COMMENT) that run from that position until the
      * end.
      * @type {Array.<Number|String>}
      */
    var decorations = isMarkup
        ? PR_decorateMarkup(source)
        : PR_decorateSource(source);

    // Integrate the decorations and tags back into the source code to produce
    // a decorated html string.
    return PR_recombineTagsAndDecorations(source, extractedTags, decorations);
  } catch (e) {
    if ('console' in window) {
      console.log(e);
      console.trace();
    }
    return sourceCodeHtml;
  }
}

var PR_SHOULD_USE_CONTINUATION = true;
/** find all the < pre > and < code > tags in the DOM with class=prettyprint and
  * prettify them.
  * @param {Function} opt_whenDone if specified, called when the last entry
  *     has been finished.
  */
function prettyPrint(opt_whenDone) {
  // fetch a list of nodes to rewrite
  var codeSegments = [
      document.getElementsByTagName('pre'),
      document.getElementsByTagName('code'),
      document.getElementsByTagName('xmp') ];
  var elements = [];
  for (var i = 0; i < codeSegments.length; ++i) {
    for (var j = 0; j < codeSegments[i].length; ++j) {
      elements.push(codeSegments[i][j]);
    }
  }
  codeSegments = null;

  // the loop is broken into a series of continuations to make sure that we
  // don't make the browser unresponsive when rewriting a large page.
  var k = 0;

  function doWork() {
    var endTime = (PR_SHOULD_USE_CONTINUATION
                   ? new Date().getTime() + 250
                   : Infinity);
    for (; k < elements.length && new Date().getTime() < endTime; k++) {
      var cs = elements[k];
      if (cs.className && cs.className.indexOf('prettyprint') >= 0) {

        // make sure this is not nested in an already prettified element
        var nested = false;
        for (var p = cs.parentNode; p != null; p = p.parentNode) {
          if ((p.tagName == 'pre' || p.tagName == 'code' ||
               p.tagName == 'xmp') &&
              p.className && p.className.indexOf('prettyprint') >= 0) {
            nested = true;
            break;
          }
        }
        if (!nested) {
          // fetch the content as a snippet of properly escaped HTML.
          // Firefox adds newlines at the end.
          var content = PR_getInnerHtml(cs);
          content = content.replace(/(?:\r\n?|\n)$/, '');

          // do the pretty printing
          var newContent = prettyPrintOne(content);

          // push the prettified html back into the tag.
          if (!PR_isRawContent(cs)) {
            // just replace the old html with the new
            cs.innerHTML = newContent;
          } else {
            // we need to change the tag to a <pre> since <xmp>s do not allow
            // embedded tags such as the span tags used to attach styles to
            // sections of source code.
            var pre = document.createElement('PRE');
            for (var i = 0; i < cs.attributes.length; ++i) {
              var a = cs.attributes[i];
              if (a.specified) {
                pre.setAttribute(a.name, a.value);
              }
            }
            pre.innerHTML = newContent;
            // remove the old
            cs.parentNode.replaceChild(pre, cs);
          }
        }
      }
    }
    if (k < elements.length) {
      // finish up in a continuation
      setTimeout(doWork, 250);
    } else if (opt_whenDone) {
      opt_whenDone();
    }
  }

  doWork();
}
