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/*******************************************************************************
* Copyright 2014 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;
import java.util.*;
import com.univocity.parsers.common.fields.*;
import com.univocity.parsers.common.input.*;
/**
* The ParserOutput is the component that manages records parsed by {@link AbstractParser} and their values.
*
* It is solely responsible for deciding when:
*
* - parsed records should be reordered according to the fields selected in {@link CommonSettings}
* - characters and values parsed in {@link AbstractParser#parseRecord()} should be retained or discarded
* - input headers should be loaded from the records parsed in {@link AbstractParser#parseRecord()} or from {@link CommonSettings#getHeaders()}
*
*
* Implementations of this class are made available to concrete parser implementations of {@link AbstractParser}.
*
* @see AbstractParser
* @see CommonSettings
*
* @author uniVocity Software Pty Ltd - [email protected]
*
*/
public class ParserOutput {
/**
* Keeps track of the current column being parsed in the input.
* Calls to {@link ParserOutput#valueParsed} and {@link ParserOutput#emptyParsed} will increase the column count.
* This value is reset to zero after a row is parsed.
*/
int column = 0;
/**
* Stores the values parsed for a record.
*/
private final String[] parsedValues;
/**
* Stores (shared) references to {@link CharAppender} for each potential column (as given by {@link CommonSettings#getMaxColumns()}).
*
Fields that are not selected will receive an instance of {@link NoopCharAppender} so all parser calls in {@link AbstractParser#parseRecord()} to {@link ParserOutput#appender} will do nothing.
*
Selected fields (given by {@link CommonParserSettings}) will receive a functional {@link CharAppender}.
*/
private CharAppender[] appenders;
private final CommonParserSettings settings;
private final boolean skipEmptyLines;
private final String nullValue;
/**
*
The appender available to parsers for accumulating characters read from the input.
*
This attribute is assigned to different instances of CharAppender during parsing process, namely, a (potentially) different CharAppender for each parsed column, taken from {@link ParserOutput#appenders}[{@link ParserOutput#column}]
*/
public CharAppender appender;
private boolean columnsToExtractInitialized;
private boolean columnsReordered;
private String[] headers;
private int[] selectedIndexes;
private long currentRecord;
/**
* Initializes the ParserOutput with the configuration specified in {@link CommonParserSettings}
* @param settings the parser configuration
*/
public ParserOutput(CommonParserSettings settings) {
this.appender = settings.newCharAppender();
this.parsedValues = new String[settings.getMaxColumns()];
this.appenders = new CharAppender[settings.getMaxColumns()];
Arrays.fill(appenders, appender);
this.settings = settings;
this.skipEmptyLines = settings.getSkipEmptyLines();
this.nullValue = settings.getNullValue();
this.columnsToExtractInitialized = false;
this.currentRecord = 0;
}
void initializeHeaders() {
columnsToExtractInitialized = true;
columnsReordered = false;
selectedIndexes = null;
this.appender = settings.newCharAppender();
Arrays.fill(appenders, appender);
this.headers = settings.getHeaders();
if (headers != null) {
headers = headers.clone();
initializeColumnsToExtract(headers);
} else if (column > 0) { //we only initialize headers from a parsed row if it is not empty
initializeColumnsToExtract(Arrays.copyOf(parsedValues, column));
if (settings.isHeaderExtractionEnabled()) {
headers = new String[column];
System.arraycopy(parsedValues, 0, headers, 0, column);
}
}
}
/**
* Gets all values parsed in the {@link ParserOutput#parsedValues} array
* @return the sequence of parsed values in a record.
*/
public String[] rowParsed() {
// some values were parsed. Let's return them
if (column > 0) {
// identifies selected columns and headers (in the first non-empty row)
if (!columnsToExtractInitialized) {
initializeHeaders();
//skips the header row. We want to use the headers defined in the settings.
if (settings.isHeaderExtractionEnabled()) {
Arrays.fill(parsedValues, null);
column = 0;
this.appender = appenders[0];
return null;
}
}
currentRecord++;
if (columnsReordered) {
String[] reorderedValues = new String[selectedIndexes.length];
for (int i = 0; i < selectedIndexes.length; i++) {
int index = selectedIndexes[i];
if (index >= column) {
reorderedValues[i] = nullValue;
} else {
reorderedValues[i] = parsedValues[index];
}
}
column = 0;
this.appender = appenders[0];
return reorderedValues;
} else {
String[] out = new String[column];
System.arraycopy(parsedValues, 0, out, 0, column);
column = 0;
this.appender = appenders[0];
return out;
}
} else if (!skipEmptyLines) { //no values were parsed, but we are not skipping empty lines
if (!columnsToExtractInitialized) {
initializeHeaders();
}
currentRecord++;
if (columnsReordered) {
String[] out = new String[selectedIndexes.length];
Arrays.fill(out, nullValue);
return out;
}
return ArgumentUtils.EMPTY_STRING_ARRAY;
}
// no values were parsed and we do not care about empty lines.
return null;
}
/**
* Initializes the sequence of selected fields, if any.
* @param values a sequence of values that represent the headers of the input. This can be either a parsed record or the headers as defined in {@link CommonSettings#getHeaders()}
*/
private void initializeColumnsToExtract(String[] values) {
FieldSelector selector = settings.getFieldSelector();
if (selector != null) {
selectedIndexes = selector.getFieldIndexes(values);
if (selectedIndexes != null) {
Arrays.fill(appenders, NoopCharAppender.getInstance());
for (int i = 0; i < selectedIndexes.length; i++) {
appenders[selectedIndexes[i]] = appender;
}
columnsReordered = settings.isColumnReorderingEnabled();
if (!columnsReordered && values.length < appenders.length) {
Arrays.fill(appenders, values.length, appenders.length, appender);
}
}
}
}
/**
* Returns the sequence of values that represent the headers each field in the input. This can be either a parsed record or the headers as defined in {@link CommonSettings#getHeaders()}
* @return the headers each field in the input
*/
public String[] getHeaders() {
return this.headers;
}
/**
* Returns the selected indexes of all fields as defined in {@link CommonSettings}. Null if no fields were selected.
* @return the selected indexes of all fields as defined in {@link CommonSettings}. Null if no fields were selected.
*/
public int[] getSelectedIndexes() {
return this.selectedIndexes;
}
/**
* Indicates whether fields selected using the field selection methods (in {@link CommonSettings}) are being reordered.
*
* @return
*
false if no fields were selected or column reordering has been disabled in {@link CommonParserSettings#isColumnReorderingEnabled()}
*
true if fields were selected and column reordering has been enabled in {@link CommonParserSettings#isColumnReorderingEnabled()}
*/
public boolean isColumnReorderingEnabled() {
return columnsReordered;
}
/**
* Returns the position of the current parsed value
* @return the position of the current parsed value
*/
public int getCurrentColumn() {
return column;
}
/**
* Adds a nullValue (as specified in {@link CommonSettings#getNullValue()}) to the output and prepares the next position in the record to receive more values.
*/
public void emptyParsed() {
this.parsedValues[column++] = nullValue;
this.appender = appenders[column];
}
/**
* Adds the accumulated value in the appender object to the output and prepares the next position in the record to receive more values.
*/
public void valueParsed() {
this.parsedValues[column++] = appender.getAndReset();
this.appender = appenders[column];
}
/**
* Returns the current record index. The number returned here reflects the number of actually parsed and valid records sent to the output of {@link ParserOutput#rowParsed}.
* @return the current record index.
*/
public long getCurrentRecord() {
return currentRecord;
}
/**
* Discards the values parsed so far
*/
public final void discardValues() {
column = 0;
this.appender = appenders[0];
}
}