/*
* Copyright 2014 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.gwt.core.ext.soyc;
import com.google.gwt.dev.jjs.SourceInfo;
import com.google.gwt.thirdparty.debugging.sourcemap.FilePosition;
import com.google.gwt.thirdparty.debugging.sourcemap.SourceMapGenerator;
/**
* Writes a sorted stream of mappings to a sourcemap. Automatically merges mappings that have
* adjacent or overlapping JavaScript ranges and also point to the same Java line.
*/
class SourceMappingWriter {
private final SourceMapGenerator out;
// There may be zero or one mappings in the buffer.
// It's represented as separate fields to avoid unnecessary memory allocation.
private boolean empty;
private String javaFile;
private int javaLine; // one-based
// the JavaScript range so far (zero-based)
private int startLine;
private int startColumn;
private int endLine;
private int endColumn;
SourceMappingWriter(SourceMapGenerator out) {
this.out = out;
this.empty = true;
}
/**
* Sends one mapping to the sourcemap.
*
* <p>The mappings must be sorted by JavaScript starting position.
*
* <p>The output is buffered, so the caller must call {@link #flush} when done.
*/
void addMapping(Range nextRange, String javaName) {
SourceInfo nextInfo = nextRange.getSourceInfo();
if (!canMerge(nextRange, nextInfo, javaName)) {
flush(null);
}
if (empty) {
// Start a new range.
javaFile = nextInfo.getFileName();
javaLine = nextInfo.getStartLine();
startLine = nextRange.getStartLine();
startColumn = nextRange.getStartColumn();
endLine = nextRange.getEndLine();
endColumn = nextRange.getEndColumn();
empty = false;
if (javaName != null) {
flush(javaName); // Don't merge mappings with Java names.
}
return;
}
// Merge with the buffer by adjusting the end of the JavaScript range if needed.
// (It's rarely needed because the range of a Java statement usually comes before
// any subexpressions within that statement, and there is rarely more than one Java
// statement per line.)
int nextEndLine = nextRange.getEndLine();
if (nextEndLine < endLine) {
return; // The multi-line range in the buffer already covers it.
}
int nextEndColumn = nextRange.getEndColumn();
if (nextEndLine == endLine && nextEndColumn <= endColumn) {
return; // The range in the buffer already covers it.
}
endLine = nextEndLine;
endColumn = nextEndColumn;
}
/**
* Writes any buffered mappings to the source map generator.
*/
void flush() {
flush(null);
}
/**
* Returns true if there is a mapping in the buffer that we can merge with.
*/
private boolean canMerge(Range nextRange, SourceInfo nextInfo, String javaName) {
if (empty) {
return false; // Nothing in the buffer.
}
if (javaName != null) {
return false; // Don't merge mappings with Java names.
}
// The ranges were sorted by starting position. Therefore we only need to to check
// that our ending position touches or overlaps their starting position.
if (endLine < nextRange.getStartLine()) {
return false; // Not adjacent because they're on separate JavaScript lines.
}
if (endLine == nextRange.getStartLine() && endColumn < nextRange.getStartColumn()) {
// Not adjacent due to unmapped characters between JavaScript ranges.
// (In theory we could relax this check if there is only whitespace between
// JavaScript ranges due to pretty-printing.)
return false;
}
if (javaLine != nextInfo.getStartLine()) {
return false; // They don't map to the same Java line.
}
return javaFile.equals(nextInfo.getFileName());
}
/**
* Flush the mapping in the buffer and annotate it with the given Java name.
*/
private void flush(String javaName) {
if (empty) {
return;
}
// Starting with V3, SourceMap line numbers are zero-based.
// GWT's line numbers for Java files originally came from the JDT, which is 1-based,
// so adjust them here to avoid an off-by-one error in debuggers.
out.addMapping(javaFile, javaName,
new FilePosition(javaLine - 1, 0),
new FilePosition(startLine, startColumn),
new FilePosition(endLine, endColumn));
empty = true; // don't write it twice.
}
}