// Copyright (C) 2009 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
* Registers a language handler for CSS.
*
*
* To use, include prettify.js and this file in your HTML page.
* Then put your code in an HTML tag like
* <pre class="prettyprint lang-css"></pre>
*
*
* http://www.w3.org/TR/CSS21/grammar.html Section G2 defines the lexical
* grammar. This scheme does not recognize keywords containing escapes.
*
* @author mikesamuel@gmail.com
*/
// This file is a call to a function defined in prettify.js which defines a
// lexical scanner for CSS and maps tokens to styles.
// The call to PR['registerLangHandler'] is quoted so that Closure Compiler
// will not rename the call so that this language extensions can be
// compiled/minified separately from one another. Other symbols defined in
// prettify.js are similarly quoted.
// The call is structured thus:
// PR['registerLangHandler'](
// PR['createSimpleLexer'](
// shortcutPatterns,
// fallThroughPatterns),
// [languageId0, ..., languageIdN])
// Langugage IDs
// =============
// The language IDs are typically the file extensions of source files for
// that language so that users can syntax highlight arbitrary files based
// on just the extension. This is heuristic, but works pretty well in
// practice.
// Patterns
// ========
// Lexers are typically implemented as a set of regular expressions.
// The SimpleLexer function takes regular expressions, styles, and some
// pragma-info and produces a lexer. A token description looks like
// [STYLE_NAME, /regular-expression/, pragmas]
// Initially, simple lexer's inner loop looked like:
// while sourceCode is not empty:
// try each regular expression in order until one matches
// remove the matched portion from sourceCode
// This was really slow for large files because some JS interpreters
// do a buffer copy on the matched portion which is O(n*n)
// The current loop now looks like
// 1. use js-modules/combinePrefixPatterns.js to
// combine all regular expressions into one
// 2. use a single global regular expresion match to extract all tokens
// 3. for each token try regular expressions in order until one matches it
// and classify it using the associated style
// This is a lot more efficient but it does mean that lookahead and lookbehind
// can't be used across boundaries to classify tokens.
// Sometimes we need lookahead and lookbehind and sometimes we want to handle
// embedded language -- JavaScript or CSS embedded in HTML, or inline assembly
// in C.
// If a particular pattern has a numbered group, and its style pattern starts
// with "lang-" as in
// ['lang-js', /<script>(.*?)<\/script>/]
// then the token classification step breaks the token into pieces.
// Group 1 is re-parsed using the language handler for "lang-js", and the
// surrounding portions are reclassified using the current language handler.
// This mechanism gives us both lookahead, lookbehind, and language embedding.
// Shortcut Patterns
// =================
// A shortcut pattern is one that is tried before other patterns if the first
// character in the token is in the string of characters.
// This very effectively lets us make quick correct decisions for common token
// types.
// All other patterns are fall-through patterns.
// The comments inline below refer to productions in the CSS specification's
// lexical grammar. See link above.
PR['registerLangHandler'](
PR['createSimpleLexer'](
// Shortcut patterns.
[
// The space production <s>
[PR['PR_PLAIN'], /^[ \t\r\n\f]+/, null, ' \t\r\n\f']
],
// Fall-through patterns.
[
// Quoted strings. <string1> and <string2>
[PR['PR_STRING'],
/^\"(?:[^\n\r\f\\\"]|\\(?:\r\n?|\n|\f)|\\[\s\S])*\"/, null],
[PR['PR_STRING'],
/^\'(?:[^\n\r\f\\\']|\\(?:\r\n?|\n|\f)|\\[\s\S])*\'/, null],
['lang-css-str', /^url\(([^\)\"\']+)\)/i],
[PR['PR_KEYWORD'],
/^(?:url|rgb|\!important|@import|@page|@media|@charset|inherit)(?=[^\-\w]|$)/i,
null],
// A property name -- an identifier followed by a colon.
['lang-css-kw', /^(-?(?:[_a-z]|(?:\\[0-9a-f]+ ?))(?:[_a-z0-9\-]|\\(?:\\[0-9a-f]+ ?))*)\s*:/i],
// A C style block comment. The <comment> production.
[PR['PR_COMMENT'], /^\/\*[^*]*\*+(?:[^\/*][^*]*\*+)*\//],
// Escaping text spans
[PR['PR_COMMENT'], /^(?:<!--|-->)/],
// A number possibly containing a suffix.
[PR['PR_LITERAL'], /^(?:\d+|\d*\.\d+)(?:%|[a-z]+)?/i],
// A hex color
[PR['PR_LITERAL'], /^#(?:[0-9a-f]{3}){1,2}\b/i],
// An identifier
[PR['PR_PLAIN'],
/^-?(?:[_a-z]|(?:\\[\da-f]+ ?))(?:[_a-z\d\-]|\\(?:\\[\da-f]+ ?))*/i],
// A run of punctuation
[PR['PR_PUNCTUATION'], /^[^\s\w\'\"]+/]
]),
['css']);
// Above we use embedded languages to highlight property names (identifiers
// followed by a colon) differently from identifiers in values.
PR['registerLangHandler'](
PR['createSimpleLexer']([],
[
[PR['PR_KEYWORD'],
/^-?(?:[_a-z]|(?:\\[\da-f]+ ?))(?:[_a-z\d\-]|\\(?:\\[\da-f]+ ?))*/i]
]),
['css-kw']);
// The content of an unquoted URL literal like url(http://foo/img.png) should
// be colored as string content. This language handler is used above in the
// URL production to do so.
PR['registerLangHandler'](
PR['createSimpleLexer']([],
[
[PR['PR_STRING'], /^[^\)\"\']+/]
]),
['css-str']);
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