| /* |
| * Copyright (C) 2011 The Android Open Source Project |
| * |
| * 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 android.filterfw.io; |
| |
| import java.util.regex.Matcher; |
| import java.util.regex.Pattern; |
| |
| /** |
| * @hide |
| */ |
| public class PatternScanner { |
| |
| private String mInput; |
| private Pattern mIgnorePattern; |
| private int mOffset = 0; |
| private int mLineNo = 0; |
| private int mStartOfLine = 0; |
| |
| public PatternScanner(String input) { |
| mInput = input; |
| } |
| |
| public PatternScanner(String input, Pattern ignorePattern) { |
| mInput = input; |
| mIgnorePattern = ignorePattern; |
| skip(mIgnorePattern); |
| } |
| |
| public String tryEat(Pattern pattern) { |
| // Skip ignore pattern |
| if (mIgnorePattern != null) { |
| skip(mIgnorePattern); |
| } |
| |
| // Create the matcher |
| Matcher matcher = pattern.matcher(mInput); |
| matcher.region(mOffset, mInput.length()); |
| |
| // Attempt to match |
| String result = null; |
| if (matcher.lookingAt()) { |
| updateLineCount(mOffset, matcher.end()); |
| mOffset = matcher.end(); |
| result = mInput.substring(matcher.start(), matcher.end()); |
| } |
| |
| // Skip ignore pattern |
| if (result != null && mIgnorePattern != null) { |
| skip(mIgnorePattern); |
| } |
| |
| return result; |
| } |
| |
| public String eat(Pattern pattern, String tokenName) { |
| String result = tryEat(pattern); |
| if (result == null) { |
| throw new RuntimeException(unexpectedTokenMessage(tokenName)); |
| } |
| return result; |
| } |
| |
| public boolean peek(Pattern pattern) { |
| // Skip ignore pattern |
| if (mIgnorePattern != null) { |
| skip(mIgnorePattern); |
| } |
| |
| // Create the matcher |
| Matcher matcher = pattern.matcher(mInput); |
| matcher.region(mOffset, mInput.length()); |
| |
| // Attempt to match |
| return matcher.lookingAt(); |
| } |
| |
| public void skip(Pattern pattern) { |
| Matcher matcher = pattern.matcher(mInput); |
| matcher.region(mOffset, mInput.length()); |
| if (matcher.lookingAt()) { |
| updateLineCount(mOffset, matcher.end()); |
| mOffset = matcher.end(); |
| } |
| } |
| |
| public boolean atEnd() { |
| return mOffset >= mInput.length(); |
| } |
| |
| public int lineNo() { |
| return mLineNo; |
| } |
| |
| public String unexpectedTokenMessage(String tokenName) { |
| String line = mInput.substring(mStartOfLine, mOffset); |
| return "Unexpected token on line " + (mLineNo + 1) + " after '" + line + "' <- Expected " + |
| tokenName + "!"; |
| } |
| |
| public void updateLineCount(int start, int end) { |
| for (int i = start; i < end; ++i) { |
| if (mInput.charAt(i) == '\n') { |
| ++mLineNo; |
| mStartOfLine = i + 1; |
| } |
| } |
| } |
| } |