Java tutorial
/* * 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.googlejavaformat.java; import com.google.common.base.CharMatcher; import com.google.common.base.Strings; import com.google.googlejavaformat.CommentsHelper; import com.google.googlejavaformat.Input.Tok; import com.google.googlejavaformat.Newlines; import com.google.googlejavaformat.java.javadoc.JavadocFormatter; import java.util.ArrayList; import java.util.Iterator; import java.util.List; import java.util.regex.Matcher; import java.util.regex.Pattern; /** {@code JavaCommentsHelper} extends {@link CommentsHelper} to rewrite Java comments. */ public final class JavaCommentsHelper implements CommentsHelper { private final String lineSeparator; public JavaCommentsHelper(String lineSeparator, JavaFormatterOptions options) { this.lineSeparator = lineSeparator; } @Override public String rewrite(Tok tok, int maxWidth, int column0) { if (!tok.isComment()) { return tok.getOriginalText(); } String text = tok.getOriginalText(); if (tok.isJavadocComment()) { text = JavadocFormatter.formatJavadoc(text, column0); } List<String> lines = new ArrayList<>(); Iterator<String> it = Newlines.lineIterator(text); while (it.hasNext()) { lines.add(CharMatcher.whitespace().trimTrailingFrom(it.next())); } if (tok.isSlashSlashComment()) { return indentLineComments(lines, column0); } else if (javadocShaped(lines)) { return indentJavadoc(lines, column0); } else { return preserveIndentation(lines, column0); } } // For non-javadoc-shaped block comments, shift the entire block to the correct // column, but do not adjust relative indentation. private String preserveIndentation(List<String> lines, int column0) { StringBuilder builder = new StringBuilder(); // find the leftmost non-whitespace character in all trailing lines int startCol = -1; for (int i = 1; i < lines.size(); i++) { int lineIdx = CharMatcher.whitespace().negate().indexIn(lines.get(i)); if (lineIdx >= 0 && (startCol == -1 || lineIdx < startCol)) { startCol = lineIdx; } } // output the first line at the current column builder.append(lines.get(0)); // output all trailing lines with plausible indentation for (int i = 1; i < lines.size(); ++i) { builder.append(lineSeparator).append(Strings.repeat(" ", column0)); // check that startCol is valid index, e.g. for blank lines if (lines.get(i).length() >= startCol) { builder.append(lines.get(i).substring(startCol)); } else { builder.append(lines.get(i)); } } return builder.toString(); } // Wraps and re-indents line comments. private String indentLineComments(List<String> lines, int column0) { lines = wrapLineComments(lines, column0); StringBuilder builder = new StringBuilder(); builder.append(lines.get(0).trim()); String indentString = Strings.repeat(" ", column0); for (int i = 1; i < lines.size(); ++i) { builder.append(lineSeparator).append(indentString).append(lines.get(i).trim()); } return builder.toString(); } // Preserve special `//noinspection` and `//$NON-NLS-x$` comments used by IDEs, which cannot // contain leading spaces. private static final Pattern LINE_COMMENT_MISSING_SPACE_PREFIX = Pattern .compile("^(//+)(?!noinspection|\\$NON-NLS-\\d+\\$)[^\\s/]"); private List<String> wrapLineComments(List<String> lines, int column0) { List<String> result = new ArrayList<>(); for (String line : lines) { // Add missing leading spaces to line comments: `//foo` -> `// foo`. Matcher matcher = LINE_COMMENT_MISSING_SPACE_PREFIX.matcher(line); if (matcher.find()) { int length = matcher.group(1).length(); line = Strings.repeat("/", length) + " " + line.substring(length); } if (line.startsWith("// MOE:")) { // don't wrap comments for https://github.com/google/MOE result.add(line); continue; } while (line.length() + column0 > Formatter.MAX_LINE_LENGTH) { int idx = Formatter.MAX_LINE_LENGTH - column0; // only break on whitespace characters, and ignore the leading `// ` while (idx >= 2 && !CharMatcher.whitespace().matches(line.charAt(idx))) { idx--; } if (idx <= 2) { break; } result.add(line.substring(0, idx)); line = "//" + line.substring(idx); } result.add(line); } return result; } // Remove leading whitespace (trailing was already removed), and re-indent. // Add a +1 indent before '*', and add the '*' if necessary. private String indentJavadoc(List<String> lines, int column0) { StringBuilder builder = new StringBuilder(); builder.append(lines.get(0).trim()); int indent = column0 + 1; String indentString = Strings.repeat(" ", indent); for (int i = 1; i < lines.size(); ++i) { builder.append(lineSeparator).append(indentString); String line = lines.get(i).trim(); if (!line.startsWith("*")) { builder.append("* "); } builder.append(line); } return builder.toString(); } // Returns true if the comment looks like javadoc private static boolean javadocShaped(List<String> lines) { Iterator<String> it = lines.iterator(); if (!it.hasNext()) { return false; } String first = it.next().trim(); // if it's actually javadoc, we're done if (first.startsWith("/**")) { return true; } // if it's a block comment, check all trailing lines for '*' if (!first.startsWith("/*")) { return false; } while (it.hasNext()) { if (!it.next().trim().startsWith("*")) { return false; } } return true; } }