blaze-base/src/com/google/idea/blaze/base/lang/buildfile/formatting/BuildBraceMatcher.java

/*
 * Copyright 2016 The Bazel Authors. All rights reserved.
 *
 * 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.idea.blaze.base.lang.buildfile.formatting;

import com.google.idea.blaze.base.lang.buildfile.lexer.BuildToken;
import com.google.idea.blaze.base.lang.buildfile.lexer.TokenKind;
import com.intellij.lang.BracePair;
import com.intellij.lang.PairedBraceMatcher;
import com.intellij.psi.PsiFile;
import com.intellij.psi.tree.IElementType;
import com.intellij.psi.tree.TokenSet;

import javax.annotation.Nullable;
import java.util.Arrays;

/**
 * This adds a close brace automatically once an opening brace is typed by the user in the editor.
 */
public class BuildBraceMatcher implements PairedBraceMatcher {

  private static final BracePair[] PAIRS = new BracePair[] {
    new BracePair(BuildToken.fromKind(TokenKind.LPAREN), BuildToken.fromKind(TokenKind.RPAREN), true),
    new BracePair(BuildToken.fromKind(TokenKind.LBRACKET), BuildToken.fromKind(TokenKind.RBRACKET), true),
    new BracePair(BuildToken.fromKind(TokenKind.LBRACE), BuildToken.fromKind(TokenKind.RBRACE), true)
  };

  private static final TokenSet BRACES_ALLOWED_BEFORE = tokenSet(
    TokenKind.NEWLINE,
    TokenKind.WHITESPACE,
    TokenKind.COMMENT,
    TokenKind.COLON,
    TokenKind.COMMA,
    TokenKind.RPAREN,
    TokenKind.RBRACKET,
    TokenKind.RBRACE,
    TokenKind.LBRACE
  );

  @Override
  public BracePair[] getPairs() {
    return PAIRS;
  }

  @Override
  public boolean isPairedBracesAllowedBeforeType(IElementType lbraceType, @Nullable IElementType contextType) {
    return contextType == null || BRACES_ALLOWED_BEFORE.contains(contextType);
  }

  @Override
  public int getCodeConstructStart(PsiFile file, int openingBraceOffset) {
    return openingBraceOffset;
  }

  private static TokenSet tokenSet(TokenKind... kind) {
    return TokenSet.create(
      Arrays.stream(kind)
        .map(BuildToken::fromKind)
        .toArray(IElementType[]::new)
    );
  }
}