com.google.common.css.compiler.ast.ChunkAware Maven / Gradle / Ivy

Go to download

Show more of this group Show more artifacts with this name
Show all versions of closure-stylesheets Show documentation

Closure Stylesheets is an extension to CSS that adds variables, functions, conditionals, and mixins to standard CSS. The tool also supports minification, linting, RTL flipping, and CSS class renaming.

There is a newer version: 20160212

Show newest version

/*
 * Copyright 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.
 */

package com.google.common.css.compiler.ast;

/**
 * Interface to annotate CSS nodes with target CSS chunk id.
 *
 * Compiled CSS can be split into multiple parts to serve them separately,
 * improving page load and browser's CSS parsing time. These parts are called
 * chunks. Usually source code of a CSS chunk is a small group of CSS/GSS
 * files.
 *
 * 
Because of inter-chunk dependencies (constant definitions and their
 * references, and rules order) chunks are parsed and processed as a single
 * file. On top of that, CSS size optimizations mix CSS rules coming from many
 * chunks. The {@link ChunkAware} interface is used to preserve the chunk
 * information during all those operations. Chunk information attached to a CSS
 * node is used to print the optimized CSS AST into separate chunks. It can
 * also be used to preserve CSS correctness while performing optimizations.
 *
 * The chunk id is represented as a general {@link Object} so that
 * the user can choose a representation that it convenient for their
 * task. In particular, tests simply use {@link String} as chunk
 * ids. The type of the chunk ids cannot be parameterized because of
 * the strange inheritance hierarchy of the CSS AST. Chunks are identified
 * using {@link Object#equals}.
 *
 * @author [email protected] (Damian Gajda)
 */
public interface ChunkAware {

  /**
   * Sets the chunk id on the node.
   *
   * @param chunk an object identifying a chunk
   */
  public void setChunk(Object chunk);

  /**
   * Gets the chunk id of the node.
   *
   * @return the chunk id or {@code null} if no chunk id was previously set
   */
  public Object getChunk();
}