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Closure Compiler is a JavaScript optimizing compiler. It parses your
JavaScript, analyzes it, removes dead code and rewrites and minimizes
what's left. It also checks syntax, variable references, and types, and
warns about common JavaScript pitfalls. It is used in many of Google's
JavaScript apps, including Gmail, Google Web Search, Google Maps, and
Google Docs.
/*
* Copyright 2009 The Closure Compiler Authors.
*
* 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.javascript.jscomp;
import static java.nio.charset.StandardCharsets.UTF_8;
import com.google.common.annotations.VisibleForTesting;
import com.google.common.io.CharStreams;
import com.google.common.io.Files;
import com.google.javascript.rhino.jstype.StaticSourceFile;
import java.io.File;
import java.io.FileReader;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.Reader;
import java.io.Serializable;
import java.io.StringReader;
import java.nio.charset.Charset;
import java.util.Arrays;
/**
* An abstract representation of a source file that provides access to
* language-neutral features. The source file can be loaded from various
* locations, such as from disk or from a preloaded string.
*
* @author [email protected] (Nick Santos)
*/
public class SourceFile implements StaticSourceFile, Serializable {
private static final long serialVersionUID = 1L;
/** A JavaScript source code provider. The value should
* be cached so that the source text stays consistent throughout a single
* compile. */
public interface Generator {
public String getCode();
}
/**
* Number of lines in the region returned by {@link #getRegion(int)}.
* This length must be odd.
*/
private static final int SOURCE_EXCERPT_REGION_LENGTH = 5;
private final String fileName;
private boolean isExternFile = false;
// The fileName may not always identify the original file - for example,
// supersourced Java inputs, or Java inputs that come from Jar files. This
// is an optional field that the creator of an AST or SourceFile can set.
// It could be a path to the original file, or in case this SourceFile came
// from a Jar, it could be the path to the Jar.
private String originalPath = null;
// Source Line Information
private int[] lineOffsets = null;
private String code = null;
/**
* Construct a new abstract source file.
*
* @param fileName The file name of the source file. It does not necessarily
* need to correspond to a real path. But it should be unique. Will
* appear in warning messages emitted by the compiler.
*/
public SourceFile(String fileName) {
if (fileName == null || fileName.isEmpty()) {
throw new IllegalArgumentException("a source must have a name");
}
this.fileName = fileName;
}
@Override
public int getLineOffset(int lineno) {
findLineOffsets();
if (lineno < 1 || lineno > lineOffsets.length) {
throw new IllegalArgumentException(
"Expected line number between 1 and " + lineOffsets.length +
"\nActual: " + lineno);
}
return lineOffsets[lineno - 1];
}
/** @return The number of lines in this source file. */
int getNumLines() {
findLineOffsets();
return lineOffsets.length;
}
private void findLineOffsets() {
if (lineOffsets != null) {
return;
}
try {
String[] sourceLines = getCode().split("\n");
lineOffsets = new int[sourceLines.length];
for (int ii = 1; ii < sourceLines.length; ++ii) {
lineOffsets[ii] =
lineOffsets[ii - 1] + sourceLines[ii - 1].length() + 1;
}
} catch (IOException e) {
lineOffsets = new int[1];
lineOffsets[0] = 0;
}
}
//////////////////////////////////////////////////////////////////////////////
// Implementation
/**
* Gets all the code in this source file.
* @throws IOException
*/
public String getCode() throws IOException {
return code;
}
/**
* Gets a reader for the code in this source file.
*/
public Reader getCodeReader() throws IOException {
return new StringReader(getCode());
}
@VisibleForTesting
String getCodeNoCache() {
return code;
}
private void setCode(String sourceCode) {
code = sourceCode;
}
public String getOriginalPath() {
return originalPath != null ? originalPath : fileName;
}
public void setOriginalPath(String originalPath) {
this.originalPath = originalPath;
}
// For SourceFile types which cache source code that can be regenerated
// easily, flush the cache. We maintain the cache mostly to speed up
// generating source when displaying error messages, so dumping the file
// contents after the compile is a fine thing to do.
public void clearCachedSource() {
// By default, do nothing. Not all kinds of SourceFiles can regenerate
// code.
}
boolean hasSourceInMemory() {
return code != null;
}
/** Returns a unique name for the source file. */
@Override
public String getName() {
return fileName;
}
/** Returns whether this is an extern. */
@Override
public boolean isExtern() {
return isExternFile;
}
/** Sets that this is an extern. */
void setIsExtern(boolean newVal) {
isExternFile = newVal;
}
@Override
public int getLineOfOffset(int offset) {
findLineOffsets();
int search = Arrays.binarySearch(lineOffsets, offset);
if (search >= 0) {
return search + 1; // lines are 1-based.
} else {
int insertionPoint = -1 * (search + 1);
return Math.min(insertionPoint - 1, lineOffsets.length - 1) + 1;
}
}
@Override
public int getColumnOfOffset(int offset) {
int line = getLineOfOffset(offset);
return offset - lineOffsets[line - 1];
}
/**
* Gets the source line for the indicated line number.
*
* @param lineNumber the line number, 1 being the first line of the file.
* @return The line indicated. Does not include the newline at the end
* of the file. Returns {@code null} if it does not exist,
* or if there was an IO exception.
*/
public String getLine(int lineNumber) {
findLineOffsets();
if (lineNumber > lineOffsets.length) {
return null;
}
if (lineNumber < 1) {
lineNumber = 1;
}
int pos = lineOffsets[lineNumber - 1];
String js = "";
try {
// NOTE(nicksantos): Right now, this is optimized for few warnings.
// This is probably the right trade-off, but will be slow if there
// are lots of warnings in one file.
js = getCode();
} catch (IOException e) {
return null;
}
if (js.indexOf('\n', pos) == -1) {
// If next new line cannot be found, there are two cases
// 1. pos already reaches the end of file, then null should be returned
// 2. otherwise, return the contents between pos and the end of file.
if (pos >= js.length()) {
return null;
} else {
return js.substring(pos, js.length());
}
} else {
return js.substring(pos, js.indexOf('\n', pos));
}
}
/**
* Get a region around the indicated line number. The exact definition of a
* region is implementation specific, but it must contain the line indicated
* by the line number. A region must not start or end by a carriage return.
*
* @param lineNumber the line number, 1 being the first line of the file.
* @return The line indicated. Returns {@code null} if it does not exist,
* or if there was an IO exception.
*/
public Region getRegion(int lineNumber) {
String js = "";
try {
js = getCode();
} catch (IOException e) {
return null;
}
int pos = 0;
int startLine = Math.max(1,
lineNumber - (SOURCE_EXCERPT_REGION_LENGTH + 1) / 2 + 1);
for (int n = 1; n < startLine; n++) {
int nextpos = js.indexOf('\n', pos);
if (nextpos == -1) {
break;
}
pos = nextpos + 1;
}
int end = pos;
int endLine = startLine;
for (int n = 0; n < SOURCE_EXCERPT_REGION_LENGTH; n++, endLine++) {
end = js.indexOf('\n', end);
if (end == -1) {
break;
}
end++;
}
if (lineNumber >= endLine) {
return null;
}
if (end == -1) {
int last = js.length() - 1;
if (js.charAt(last) == '\n') {
return
new SimpleRegion(startLine, endLine, js.substring(pos, last));
} else {
return new SimpleRegion(startLine, endLine, js.substring(pos));
}
} else {
return new SimpleRegion(startLine, endLine, js.substring(pos, end));
}
}
@Override
public String toString() {
return fileName;
}
public static SourceFile fromFile(String fileName, Charset c) {
return builder().withCharset(c).buildFromFile(fileName);
}
public static SourceFile fromFile(String fileName) {
return builder().buildFromFile(fileName);
}
public static SourceFile fromFile(File file, Charset c) {
return builder().withCharset(c).buildFromFile(file);
}
public static SourceFile fromFile(File file) {
return builder().buildFromFile(file);
}
public static SourceFile fromCode(String fileName, String code) {
return builder().buildFromCode(fileName, code);
}
public static SourceFile fromCode(String fileName,
String originalPath, String code) {
return builder().withOriginalPath(originalPath)
.buildFromCode(fileName, code);
}
public static SourceFile fromInputStream(String fileName, InputStream s)
throws IOException {
return builder().buildFromInputStream(fileName, s);
}
public static SourceFile fromInputStream(String fileName,
String originalPath, InputStream s) throws IOException {
return builder().withOriginalPath(originalPath)
.buildFromInputStream(fileName, s);
}
public static SourceFile fromReader(String fileName, Reader r)
throws IOException {
return builder().buildFromReader(fileName, r);
}
public static SourceFile fromGenerator(String fileName,
Generator generator) {
return builder().buildFromGenerator(fileName, generator);
}
/** Create a new builder for source files. */
public static Builder builder() {
return new Builder();
}
/**
* A builder interface for source files.
*
* Allows users to customize the Charset, and the original path of
* the source file (if it differs from the path on disk).
*/
public static class Builder {
private Charset charset = UTF_8;
private String originalPath = null;
public Builder() {}
/** Set the charset to use when reading from an input stream or file. */
public Builder withCharset(Charset charset) {
this.charset = charset;
return this;
}
/** Set the original path to use. */
public Builder withOriginalPath(String originalPath) {
this.originalPath = originalPath;
return this;
}
public SourceFile buildFromFile(String fileName) {
return buildFromFile(new File(fileName));
}
public SourceFile buildFromFile(File file) {
return new OnDisk(file, originalPath, charset);
}
public SourceFile buildFromCode(String fileName, String code) {
return new Preloaded(fileName, originalPath, code);
}
public SourceFile buildFromInputStream(String fileName, InputStream s)
throws IOException {
return buildFromCode(fileName,
CharStreams.toString(new InputStreamReader(s, charset)));
}
public SourceFile buildFromReader(String fileName, Reader r)
throws IOException {
return buildFromCode(fileName, CharStreams.toString(r));
}
public SourceFile buildFromGenerator(String fileName,
Generator generator) {
return new Generated(fileName, originalPath, generator);
}
}
//////////////////////////////////////////////////////////////////////////////
// Implementations
/**
* A source file where the code has been preloaded.
*/
static class Preloaded extends SourceFile {
private static final long serialVersionUID = 1L;
Preloaded(String fileName, String originalPath, String code) {
super(fileName);
super.setOriginalPath(originalPath);
super.setCode(code);
}
}
/**
* A source file where the code will be dynamically generated
* from the injected interface.
*/
static class Generated extends SourceFile {
private static final long serialVersionUID = 1L;
private final Generator generator;
// Not private, so that LazyInput can extend it.
Generated(String fileName, String originalPath, Generator generator) {
super(fileName);
super.setOriginalPath(originalPath);
this.generator = generator;
}
@Override
public synchronized String getCode() throws IOException {
String cachedCode = super.getCode();
if (cachedCode == null) {
cachedCode = generator.getCode();
super.setCode(cachedCode);
}
return cachedCode;
}
// Clear out the generated code when finished with a compile; we can
// regenerate it if we ever need it again.
@Override
public void clearCachedSource() {
super.setCode(null);
}
}
/**
* A source file where the code is only read into memory if absolutely
* necessary. We will try to delay loading the code into memory as long as
* possible.
*/
static class OnDisk extends SourceFile {
private static final long serialVersionUID = 1L;
private final File file;
// This is stored as a String, but passed in and out as a Charset so that
// we can serialize the class.
// Default input file format for JSCompiler has always been UTF_8.
private String inputCharset = UTF_8.name();
OnDisk(File file, String originalPath, Charset c) {
super(file.getPath());
this.file = file;
super.setOriginalPath(originalPath);
if (c != null) {
this.setCharset(c);
}
}
@Override
public synchronized String getCode() throws IOException {
String cachedCode = super.getCode();
if (cachedCode == null) {
cachedCode = Files.toString(file, this.getCharset());
super.setCode(cachedCode);
}
return cachedCode;
}
/**
* Gets a reader for the code in this source file.
*/
@Override
public Reader getCodeReader() throws IOException {
if (hasSourceInMemory()) {
return super.getCodeReader();
} else {
// If we haven't pulled the code into memory yet, don't.
return new FileReader(file);
}
}
// Flush the cached code after the compile; we can read it off disk
// if we need it again.
@Override
public void clearCachedSource() {
super.setCode(null);
}
/**
* Store the Charset specification as the string version of the name,
* rather than the Charset itself. This allows us to serialize the
* SourceFile class.
* @param c charset to use when reading the input.
*/
public void setCharset(Charset c) {
inputCharset = c.name();
}
/**
* Get the Charset specifying how we're supposed to read the file
* in off disk and into UTF-16. This is stored as a strong to allow
* SourceFile to be serialized.
* @return Charset object representing charset to use.
*/
public Charset getCharset() {
return Charset.forName(inputCharset);
}
}
}