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/*
* Copyright 2015 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.passes;
import com.google.common.base.Preconditions;
import com.google.common.base.Predicate;
import com.google.common.base.Predicates;
import com.google.common.collect.ImmutableMap;
import com.google.common.collect.Maps;
import com.google.common.css.JobDescription.SourceMapDetailLevel;
import com.google.common.css.compiler.ast.CssNode;
import com.google.debugging.sourcemap.FilePosition;
import com.google.debugging.sourcemap.SourceMapFormat;
import com.google.debugging.sourcemap.SourceMapGenerator;
import com.google.debugging.sourcemap.SourceMapGeneratorFactory;
import com.google.debugging.sourcemap.SourceMapGeneratorV3;
import java.io.IOException;
import java.util.ArrayDeque;
import java.util.ArrayList;
import java.util.Deque;
import java.util.List;
import java.util.Map;
/**
* Class to collect and generate source map(v3) for Gss compiler. It is intended to be used by
* {@link com.google.common.css.compiler.passes.CodePrinter}.
*
* Source Map Revision 3 Proposal:
* https://docs.google.com/document/d/1U1RGAehQwRypUTovF1KRlpiOFze0b-_2gc6fAH0KY0k/edit?usp=sharing
*
* @see com.google.debugging.sourcemap.SourceMapGeneratorV3
*
* @author [email protected] (Chenyun Yang)
*/
public final class DefaultGssSourceMapGenerator implements GssSourceMapGenerator {
/** The underlying source map generator to use. */
private SourceMapGenerator generator;
/**
* Maintains a mapping from a given node's source code position to its generated output.
* This position is relative to the current run of the CodePrinter and will be normalized
* later on by the SourceMap.
*/
static class Mapping {
CssNode node;
FilePosition start;
FilePosition end;
}
/**
* Map used internally to get {@code Predicate}s from {@code DetailLevel}.
*
*
* - {@code ALL} provides the most details by generating source map for
* every nodes containing source locations.
*
- {@code DEFAULT} generates source map for selected nodes and results in
* a smaller output suitable to use in production.
*
*/
private static final Map> DETAIL_LEVEL_PREDICATES =
Maps.immutableEnumMap(ImmutableMap.of(
SourceMapDetailLevel.ALL,
Predicates.alwaysTrue(),
SourceMapDetailLevel.DEFAULT,
Predicates.alwaysTrue()));
/** Deque to hold current mappings on stack while visiting the subtree. **/
private final Deque mappings;
/** List of all the mappings generated for code visit **/
private final List allMappings;
private SourceMapDetailLevel sourceMapDetailLevel;
/** Predicate to determine whether to include current node under visit into {@code mappings}. **/
private Predicate detailLevelPredicate;
/**
* Constructor to get source map class to use.
*
* @param sourceMapDetailLevel used to control the output details of source map
*/
public DefaultGssSourceMapGenerator(SourceMapDetailLevel sourceMapDetailLevel) {
Preconditions.checkState(sourceMapDetailLevel != null);
this.mappings = new ArrayDeque<>();
this.generator = SourceMapGeneratorFactory.getInstance(SourceMapFormat.V3);
this.allMappings = new ArrayList<>();
this.sourceMapDetailLevel = sourceMapDetailLevel;
this.detailLevelPredicate = DETAIL_LEVEL_PREDICATES.get(this.sourceMapDetailLevel);
}
/**
* Appends the generated source map to {@code out}.
*
* @param out an {@link Appendable} object to append the output on
* @param name filename to be written inside the source map (not the filename where writes to)
*
* @see SourceMapGeneratorV3#appendTo
*/
@Override
public void appendOutputTo(Appendable out, String name) throws IOException {
generateSourceMap();
generator.appendTo(out, name);
}
/**
* Starts the source mapping for the given node at the current position.
* This is intended to be called before the node is written to the buffer.
*
* @param node the {@link CssNode} to be processed
* @param startLine the first character's line number once it starts writing output
* @param startCharIndex the first character's character index once it starts writing output
*/
@Override
public void startSourceMapping(CssNode node, int startLine, int startCharIndex) {
Preconditions.checkState(node != null);
Preconditions.checkState(startLine >= 0);
Preconditions.checkState(startCharIndex >= 0);
if (node.getSourceCodeLocation() != null
&& detailLevelPredicate.apply(node)) {
Mapping mapping = new Mapping();
mapping.node = node;
mapping.start = new FilePosition(startLine, startCharIndex);
mappings.push(mapping);
allMappings.add(mapping);
}
}
/**
* Finishes the source mapping for the given node at the current position.
* This is intended to be called immediately after the whole node is written to the buffer.
*
* @param node the {@link CssNode} to be processed
* @param endLine the last character's line number when it ends writing output
* @param endCharIndex the last character's character index when it ends writing output
*/
@Override
public void endSourceMapping(CssNode node, int endLine, int endCharIndex) {
Preconditions.checkState(node != null);
Preconditions.checkState(endLine >= 0);
Preconditions.checkState(endCharIndex >= 0);
if (!mappings.isEmpty() && mappings.peek().node == node) {
Mapping mapping = mappings.pop();
mapping.end = new FilePosition(endLine, endCharIndex);
}
}
/**
* Sets the prefix to be added to the beginning of each source path passed to
* {@link #addMapping} as debuggers expect (prefix + sourceName) to be a URL
* for loading the source code.
*
* @param path The URL prefix to save in the sourcemap file
*/
@Override
public void setSourceRoot(String path){
((SourceMapGeneratorV3) generator).setSourceRoot(path);
}
private void addMapping(Mapping mapping) {
CssNode node = mapping.node;
FilePosition outputStartPosition = mapping.start;
FilePosition outputEndPosition = mapping.end;
String sourceFile = getSourceFileName(node);
// If the node does not have an associated source file or source location
// is unknown, then the node does not have sufficient info for source map.
if (sourceFile == null || node.getSourceCodeLocation().isUnknown()) {
return;
}
// TODO: could pass in an optional symbol name
generator.addMapping(
sourceFile, null,
new FilePosition(getStartLineno(node), getStartCharIndex(node)),
outputStartPosition, outputEndPosition);
}
/**
* Gets the source file file for current node.
*/
private String getSourceFileName(CssNode node) {
return node.getSourceCodeLocation().getSourceCode().getFileName();
}
/**
* Gets the start line index in the source code of {@code node} adjusted to 0-based indices.
*
* Notes: Gss compiler uses a 1-based line number and source map V3 uses a 0-based line number.
*/
private int getStartLineno(CssNode node) {
return node.getSourceCodeLocation().getLineNumber() - 1;
}
/**
* Gets the start character index in the output buffer for current {@code node}.
*/
private int getStartCharIndex(CssNode node) {
return node.getSourceCodeLocation().getCharacterIndex();
}
/**
* Generates the source map by passing all mappings to {@link #generator}.
*/
private void generateSourceMap(){
for (Mapping mapping : allMappings) {
addMapping(mapping);
}
}
}