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/*
* Copyright 2016 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.palantir.javaformat.java.javadoc;
import static com.google.common.base.Preconditions.checkArgument;
import static com.google.common.base.Preconditions.checkNotNull;
import java.util.regex.Matcher;
import java.util.regex.Pattern;
/**
* String reader designed for use from the lexer. Callers invoke the {@link #tryConsume tryConsume*} methods to specify
* what characters they expect and then {@link #readAndResetRecorded} to retrieve and consume the matched characters.
* This is a slightly odd API -- why not just return the matched characters from tryConsume? -- but it is convenient for
* the lexer.
*/
final class CharStream {
String remaining;
int toConsume;
CharStream(String input) {
this.remaining = checkNotNull(input);
}
boolean tryConsume(String expected) {
if (!remaining.startsWith(expected)) {
return false;
}
toConsume = expected.length();
return true;
}
/*
* @param pattern the pattern to search for, which must be anchored to match only at position 0
*/
boolean tryConsumeRegex(Pattern pattern) {
Matcher matcher = pattern.matcher(remaining);
if (!matcher.find()) {
return false;
}
checkArgument(matcher.start() == 0);
toConsume = matcher.end();
return true;
}
String readAndResetRecorded() {
String result = remaining.substring(0, toConsume);
remaining = remaining.substring(toConsume);
toConsume = 0; // TODO(cpovirk): Set this to a bogus value here and in the constructor.
return result;
}
boolean isExhausted() {
return remaining.isEmpty();
}
}
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