de.metanome.backend.input.csv.FileIterator.java Source code

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Here is the source code for de.metanome.backend.input.csv.FileIterator.java

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/*
 * Copyright 2014 by the Metanome 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 de.metanome.backend.input.csv;

import com.google.common.collect.ImmutableList;

import au.com.bytecode.opencsv.CSVParser;
import au.com.bytecode.opencsv.CSVReader;

import de.metanome.algorithm_integration.input.InputIterationException;
import de.metanome.algorithm_integration.input.RelationalInput;

import java.io.IOException;
import java.io.Reader;

/**
 * {@link FileIterator}s are Iterators over lines in a csv file.
 *
 * @author Jakob Zwiener
 */
public class FileIterator implements RelationalInput {

    public static final boolean DEFAULT_HAS_HEADER = false;
    public static final boolean DEFAULT_SKIP_DIFFERING_LINES = false;

    protected static final String DEFAULT_HEADER_STRING = "column";

    protected CSVReader csvReader;
    protected boolean skipDifferingLines;
    protected ImmutableList<String> headerLine;
    protected ImmutableList<String> nextLine;
    protected String relationName;
    protected int numberOfColumns = 0;
    // Initialized to -1 because of lookahead
    protected int currentLineNumber = -1;

    public FileIterator(String relationName, Reader reader, char separator, char quotechar)
            throws InputIterationException {
        this(relationName, reader, separator, quotechar, CSVReader.DEFAULT_SKIP_LINES);
    }

    public FileIterator(String relationName, Reader reader, char separator, char quoteChar, int skipLines)
            throws InputIterationException {
        this(relationName, reader, separator, quoteChar, skipLines, DEFAULT_HAS_HEADER);
    }

    public FileIterator(String relationName, Reader reader, char separator, char quotechar, int skipLines,
            boolean hasHeader) throws InputIterationException {
        this(relationName, reader, separator, quotechar, CSVParser.DEFAULT_ESCAPE_CHARACTER, skipLines,
                CSVParser.DEFAULT_STRICT_QUOTES, CSVParser.DEFAULT_IGNORE_LEADING_WHITESPACE, hasHeader);
    }

    public FileIterator(String relationName, Reader reader, char separator, char quotechar, char escape,
            int skipLines, boolean strictQuotes, boolean ignoreLeadingWhiteSpace, boolean hasHeader)
            throws InputIterationException {
        this(relationName, reader, separator, quotechar, escape, skipLines, strictQuotes, ignoreLeadingWhiteSpace,
                hasHeader, DEFAULT_SKIP_DIFFERING_LINES);
    }

    public FileIterator(String relationName, Reader reader, char separator, char quotechar, char escape,
            int skipLines, boolean strictQuotes, boolean ignoreLeadingWhiteSpace, boolean hasHeader,
            boolean skipDifferingLines) throws InputIterationException {
        this.relationName = relationName;
        this.csvReader = new CSVReader(reader, separator, quotechar, escape, skipLines, strictQuotes,
                ignoreLeadingWhiteSpace);
        this.skipDifferingLines = skipDifferingLines;

        this.nextLine = readNextLine();
        if (this.nextLine != null) {
            this.numberOfColumns = this.nextLine.size();
        }

        if (hasHeader) {
            this.headerLine = this.nextLine;
            next();
        }

        // If the header is still null generate a standard header the size of number of columns.
        if (this.headerLine == null) {
            this.headerLine = generateHeaderLine();
        }
    }

    @Override
    public boolean hasNext() {
        return !(this.nextLine == null);
    }

    @Override
    public ImmutableList<String> next() throws InputIterationException {
        ImmutableList<String> currentLine = this.nextLine;

        if (currentLine == null) {
            return null;
        }
        this.nextLine = readNextLine();

        if (this.skipDifferingLines) {
            readToNextValidLine();
        } else {
            failDifferingLine(currentLine);
        }

        return currentLine;
    }

    protected void failDifferingLine(ImmutableList<String> currentLine) throws InputIterationException {
        if (currentLine.size() != this.numberOfColumns()) {
            throw new InputIterationException("Csv line length did not match on line " + currentLineNumber);
        }
    }

    protected void readToNextValidLine() throws InputIterationException {
        if (!hasNext()) {
            return;
        }

        while (this.nextLine.size() != this.numberOfColumns()) {
            this.nextLine = readNextLine();
            if (!hasNext()) {
                break;
            }
        }
    }

    protected ImmutableList<String> generateHeaderLine() {
        String[] headerArray = new String[this.numberOfColumns];
        for (Integer i = 1; i <= this.numberOfColumns; i++) {
            headerArray[i - 1] = DEFAULT_HEADER_STRING + i.toString();
        }
        return ImmutableList.copyOf(headerArray);
    }

    protected ImmutableList<String> readNextLine() throws InputIterationException {
        String[] lineArray;
        try {
            lineArray = this.csvReader.readNext();
            currentLineNumber++;
        } catch (IOException e) {
            throw new InputIterationException("Could not read next line in csv file.");
        }
        if (lineArray == null) {
            return null;
        } else {
            return ImmutableList.copyOf(lineArray);
        }
    }

    @Override
    public void close() throws IOException {
        csvReader.close();
    }

    @Override
    public int numberOfColumns() {
        return numberOfColumns;
    }

    @Override
    public String relationName() {
        return relationName;
    }

    @Override
    public ImmutableList<String> columnNames() {
        return headerLine;
    }
}