com.univocity.parsers.common.iterators.ParserIterator Maven / Gradle / Ivy
Go to download
Show more of this group Show more artifacts with this name
Show all versions of univocity-parsers Show documentation
Show all versions of univocity-parsers Show documentation
uniVocity's open source parsers for processing different text formats using a consistent API
/*******************************************************************************
* Copyright 2017 uniVocity Software Pty Ltd
*
* 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.univocity.parsers.common.iterators;
import com.univocity.parsers.common.*;
import com.univocity.parsers.common.record.*;
import java.util.*;
/**
* An {@link Iterator} over the parser enabling easy iteration against rows and records
*
* Multiple iterations are possible if Files are being fed into the parser,
* but other forms of input (such as {@code InputStream}s and {@code Reader}s) can not be iterated over more than once.
*
* @author uniVocity Software Pty Ltd - [email protected]
*/
abstract class ParserIterator implements IterableResult {
protected final AbstractParser parser;
/**
* Creates a {@code ParserIterator} using the provided {@code parser}
*
* @param parser the {@code parser} to iterate over
*/
protected ParserIterator(AbstractParser parser) {
this.parser = parser;
}
@Override
public final ParsingContext getContext() {
return parser.getContext();
}
/**
* This method is called whenever the {@code iterator} is starting to iterate over the
* results.
* an example implementation of this is:
*
*
* {@code
* @Override
* public void beginParsing(){
* parser.beginParsing(input);
* }}
*
*
* This is to allow for different input types such as {@code Reader, File, or InputStream} without large code
* reuse.
*/
protected abstract void beginParsing();
@Override
public final ResultIterator iterator() {
return new ResultIterator() {
T next;
boolean started;
@Override
public ParsingContext getContext() {
return parser.getContext();
}
@Override
public boolean hasNext() {
if (started) {
return next != null;
} else {
started = true;
beginParsing();
next = nextResult();
return next != null;
}
}
@Override
public T next() {
T out = next;
next = nextResult();
return out;
}
@Override
public void remove() {
throw new UnsupportedOperationException("Can't remove row");
}
};
}
/**
* Returns the next record (either a String[] or a {@link Record})
*
* @return the next record if available.
*/
protected abstract T nextResult();
}