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A Java source code formatter that follows Google Java Style.
/*
* Copyright 2017 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.googlejavaformat.java;
import static com.google.common.collect.ImmutableList.toImmutableList;
import com.google.common.base.CharMatcher;
import com.google.common.base.Preconditions;
import com.google.common.collect.DiscreteDomain;
import com.google.common.collect.ImmutableList;
import com.google.common.collect.Range;
import com.google.common.collect.RangeSet;
import com.google.common.collect.TreeRangeSet;
import java.util.ArrayList;
import java.util.List;
/** Formats a subset of a compilation unit. */
public class SnippetFormatter {
/** The kind of snippet to format. */
public enum SnippetKind {
COMPILATION_UNIT,
CLASS_BODY_DECLARATIONS,
STATEMENTS,
EXPRESSION
}
private class SnippetWrapper {
int offset;
final StringBuilder contents = new StringBuilder();
public SnippetWrapper append(String str) {
contents.append(str);
return this;
}
public SnippetWrapper appendSource(String source) {
this.offset = contents.length();
contents.append(source);
return this;
}
public void closeBraces(int initialIndent) {
for (int i = initialIndent; --i >= 0; ) {
contents.append("\n").append(createIndentationString(i)).append("}");
}
}
}
private static final int INDENTATION_SIZE = 2;
private final Formatter formatter = new Formatter();
private static final CharMatcher NOT_WHITESPACE = CharMatcher.whitespace().negate();
public String createIndentationString(int indentationLevel) {
Preconditions.checkArgument(
indentationLevel >= 0,
"Indentation level cannot be less than zero. Given: %s",
indentationLevel);
int spaces = indentationLevel * INDENTATION_SIZE;
StringBuilder buf = new StringBuilder(spaces);
for (int i = 0; i < spaces; i++) {
buf.append(' ');
}
return buf.toString();
}
private static Range offsetRange(Range range, int offset) {
range = range.canonical(DiscreteDomain.integers());
return Range.closedOpen(range.lowerEndpoint() + offset, range.upperEndpoint() + offset);
}
private static List> offsetRanges(List> ranges, int offset) {
List> result = new ArrayList<>();
for (Range range : ranges) {
result.add(offsetRange(range, offset));
}
return result;
}
/** Runs the Google Java formatter on the given source, with only the given ranges specified. */
public ImmutableList format(
SnippetKind kind,
String source,
List> ranges,
int initialIndent,
boolean includeComments)
throws FormatterException {
RangeSet rangeSet = TreeRangeSet.create();
for (Range range : ranges) {
rangeSet.add(range);
}
if (includeComments) {
if (kind != SnippetKind.COMPILATION_UNIT) {
throw new IllegalArgumentException(
"comment formatting is only supported for compilation units");
}
return formatter.getFormatReplacements(source, ranges);
}
SnippetWrapper wrapper = snippetWrapper(kind, source, initialIndent);
ranges = offsetRanges(ranges, wrapper.offset);
String replacement = formatter.formatSource(wrapper.contents.toString(), ranges);
replacement =
replacement.substring(
wrapper.offset,
replacement.length() - (wrapper.contents.length() - wrapper.offset - source.length()));
return toReplacements(source, replacement).stream()
.filter(r -> rangeSet.encloses(r.getReplaceRange()))
.collect(toImmutableList());
}
/**
* Generates {@code Replacement}s rewriting {@code source} to {@code replacement}, under the
* assumption that they differ in whitespace alone.
*/
private static List toReplacements(String source, String replacement) {
if (!NOT_WHITESPACE.retainFrom(source).equals(NOT_WHITESPACE.retainFrom(replacement))) {
throw new IllegalArgumentException(
"source = \"" + source + "\", replacement = \"" + replacement + "\"");
}
/*
* In the past we seemed to have problems touching non-whitespace text in the formatter, even
* just replacing some code with itself. Retrospective attempts to reproduce this have failed,
* but this may be an issue for future changes.
*/
List replacements = new ArrayList<>();
int i = NOT_WHITESPACE.indexIn(source);
int j = NOT_WHITESPACE.indexIn(replacement);
if (i != 0 || j != 0) {
replacements.add(Replacement.create(0, i, replacement.substring(0, j)));
}
while (i != -1 && j != -1) {
int i2 = NOT_WHITESPACE.indexIn(source, i + 1);
int j2 = NOT_WHITESPACE.indexIn(replacement, j + 1);
if (i2 == -1 || j2 == -1) {
break;
}
if ((i2 - i) != (j2 - j)
|| !source.substring(i + 1, i2).equals(replacement.substring(j + 1, j2))) {
replacements.add(Replacement.create(i + 1, i2, replacement.substring(j + 1, j2)));
}
i = i2;
j = j2;
}
return replacements;
}
private SnippetWrapper snippetWrapper(SnippetKind kind, String source, int initialIndent) {
/*
* Synthesize a dummy class around the code snippet provided by Eclipse. The dummy class is
* correctly formatted -- the blocks use correct indentation, etc.
*/
switch (kind) {
case COMPILATION_UNIT:
{
SnippetWrapper wrapper = new SnippetWrapper();
for (int i = 1; i <= initialIndent; i++) {
wrapper.append("class Dummy {\n").append(createIndentationString(i));
}
wrapper.appendSource(source);
wrapper.closeBraces(initialIndent);
return wrapper;
}
case CLASS_BODY_DECLARATIONS:
{
SnippetWrapper wrapper = new SnippetWrapper();
for (int i = 1; i <= initialIndent; i++) {
wrapper.append("class Dummy {\n").append(createIndentationString(i));
}
wrapper.appendSource(source);
wrapper.closeBraces(initialIndent);
return wrapper;
}
case STATEMENTS:
{
SnippetWrapper wrapper = new SnippetWrapper();
wrapper.append("class Dummy {\n").append(createIndentationString(1));
for (int i = 2; i <= initialIndent; i++) {
wrapper.append("{\n").append(createIndentationString(i));
}
wrapper.appendSource(source);
wrapper.closeBraces(initialIndent);
return wrapper;
}
case EXPRESSION:
{
SnippetWrapper wrapper = new SnippetWrapper();
wrapper.append("class Dummy {\n").append(createIndentationString(1));
for (int i = 2; i <= initialIndent; i++) {
wrapper.append("{\n").append(createIndentationString(i));
}
wrapper.append("Object o = ");
wrapper.appendSource(source);
wrapper.append(";");
wrapper.closeBraces(initialIndent);
return wrapper;
}
default:
throw new IllegalArgumentException("Unknown snippet kind: " + kind);
}
}
}