org.codehaus.groovy.control.io.AbstractReaderSource Maven / Gradle / Ivy
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* Licensed to the Apache Software Foundation (ASF) under one
* or more contributor license agreements. See the NOTICE file
* distributed with this work for additional information
* regarding copyright ownership. The ASF licenses this file
* to you 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
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* KIND, either express or implied. See the License for the
* specific language governing permissions and limitations
* under the License.
*/
package org.codehaus.groovy.control.io;
import org.codehaus.groovy.control.CompilerConfiguration;
import org.codehaus.groovy.control.Janitor;
import java.io.BufferedReader;
import java.io.IOException;
/**
* For ReaderSources that can choose a parent class, a base that
* provides common functionality.
*
* @author Chris Poirier
*/
public abstract class AbstractReaderSource implements ReaderSource {
protected CompilerConfiguration configuration; // Configuration data
public AbstractReaderSource(CompilerConfiguration configuration) {
if (configuration == null) {
throw new IllegalArgumentException("Compiler configuration must not be null!");
// ... or more relaxed?
// configuration = CompilerConfiguration.DEFAULT;
}
this.configuration = configuration;
}
/**
* Returns true if the source can be restarted (ie. if getReader()
* will return non-null on subsequent calls.
*/
public boolean canReopenSource() {
return true;
}
private BufferedReader lineSource = null; // If set, a reader on the current source file
private String line = null; // The last line read from the current source file
private int number = 0; // The last line number read
/**
* Returns a line from the source, or null, if unavailable. If
* you supply a Janitor, resources will be cached.
*/
public String getLine(int lineNumber, Janitor janitor) {
// If the source is already open and is passed the line we
// want, close it.
if (lineSource != null && number > lineNumber) {
cleanup();
}
// If the line source is closed, try to open it.
if (lineSource == null) {
try {
lineSource = new BufferedReader(getReader());
} catch (Exception e) {
// Ignore
}
number = 0;
}
// Read until the appropriate line number.
if (lineSource != null) {
while (number < lineNumber) {
try {
line = lineSource.readLine();
number++;
}
catch (IOException e) {
cleanup();
}
}
if (janitor == null) {
final String result = line; // otherwise cleanup() will wipe out value
cleanup();
return result;
} else {
janitor.register(this);
}
}
return line;
}
/**
* Cleans up any cached resources used by getLine().
*/
public void cleanup() {
if (lineSource != null) {
try {
lineSource.close();
} catch (Exception e) {
// Ignore
}
}
lineSource = null;
line = null;
number = 0;
}
}