tika-parsers/tika-parsers-standard/tika-parsers-standard-modules/tika-parser-text-module/src/main/java/org/apache/tika/parser/csv/CSVSniffer.java - tika - Git at Google

 /*
  * 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 "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 org.apache.tika.parser.csv;

 import java.io.BufferedReader;
 import java.io.EOFException;
 import java.io.IOException;
 import java.io.PushbackReader;
 import java.io.Reader;
 import java.util.ArrayList;
 import java.util.Collections;
 import java.util.HashMap;
 import java.util.List;
 import java.util.Map;

 import org.apache.commons.io.input.ProxyReader;

 import org.apache.tika.metadata.Metadata;
 import org.apache.tika.mime.MediaType;

 class CSVSniffer {
     static final int EOF = -1;
     static final int NEW_LINE = '\n';
     static final int CARRIAGE_RETURN = '\r';
     private static final int DEFAULT_MARK_LIMIT = 10000;
     private static final double DEFAULT_MIN_CONFIDENCE = 0.50;
     private static final int PUSH_BACK = 2;
     private static final int SPACE = ' ';

     private final char[] delimiters;
     private final int markLimit;
     private final double minConfidence;

     CSVSniffer(char[] delimiters) {
         this(DEFAULT_MARK_LIMIT, delimiters, DEFAULT_MIN_CONFIDENCE);
     }

     CSVSniffer(int markLimit, char[] delimiters, double minConfidence) {
         this.markLimit = markLimit;
         this.delimiters = delimiters;
         this.minConfidence = minConfidence;
     }

     List<CSVResult> sniff(Reader reader) throws IOException {
         if (!reader.markSupported()) {
             reader = new BufferedReader(reader);
         }
         List<CSVResult> ret = new ArrayList<>();
         for (char delimiter : delimiters) {
             reader.mark(markLimit);
             try {
                 CSVResult result = new Snifflet(delimiter).sniff(reader);
                 ret.add(result);
             } finally {
                 reader.reset();
             }
         }
         Collections.sort(ret);
         return ret;
     }

     /**
      * @param reader
      * @param metadata
      * @return the best result given the detection results or {@link CSVResult#TEXT}
      * if the confidence is not above a threshold.
      * @throws IOException
      */
     CSVResult getBest(Reader reader, Metadata metadata) throws IOException {
         //TODO: take into consideration the filename.  Perhaps require
         //a higher confidence if detection contradicts filename?
         List<CSVResult> results = sniff(reader);
         if (results == null || results.size() == 0) {
             return CSVResult.TEXT;
         }
         CSVResult bestResult = results.get(0);
         if (bestResult.getConfidence() < minConfidence) {
             return CSVResult.TEXT;
         }
         return bestResult;
     }

     private static class UnsurprisingEOF extends EOFException {

     }

     private static class HitMarkLimitException extends EOFException {

     }

     private static class MutableInt {
         int i;

         MutableInt(int i) {
             this.i = i;
         }

         void increment() {
             i++;
         }

         int intValue() {
             return i;
         }
     }

     //inner class that tests a single hypothesis/combination
     //of parameters for delimiter and quote character
     //this will throw an EOF before reading beyond the
     //markLimit number of characters (not bytes!)
     private class Snifflet {

         private final char delimiter;

         //hardcode this for now
         private final char quoteCharacter = '"';

         Map<Integer, MutableInt> rowLengthCounts = new HashMap<>();
         int charsRead = 0;
         int colCount = 0;
         int encapsulated = 0; //number of cells that are encapsulated in dquotes (for now)
         boolean parseException = false;

         public Snifflet(char delimiter) {
             this.delimiter = delimiter;
         }

         CSVResult sniff(Reader r) throws IOException {
             boolean eof = false;
             boolean hitMarkLimit = false;
             int lastC = -1;
             StringBuilder unquoted = new StringBuilder();
             try (PushbackReader reader = new PushbackReader(new CloseShieldReader(r), PUSH_BACK)) {
                 int c = read(reader);
                 while (c != EOF) {
                     if (c == quoteCharacter) {
                         handleUnquoted(unquoted);
                         //test to make sure there isn't an unencapsulated quote character
                         // in the middle of a cell
                         if (lastC > -1 && lastC != delimiter && lastC != NEW_LINE &&
                                 lastC != CARRIAGE_RETURN) {
                             parseException = true;
                             return calcResult();
                         }
                         //TODO: test to make sure cell doesn't start with escaped
                         // ""the quick brown cat"
                         boolean correctlyEncapsulated = consumeQuoted(reader, quoteCharacter);
                         if (!correctlyEncapsulated) {
                             parseException = true;
                             return calcResult();
                         }
                     } else if (c == delimiter) {
                         handleUnquoted(unquoted);
                         endColumn();
                         consumeSpaceCharacters(reader);
                     } else if (c == NEW_LINE || c == CARRIAGE_RETURN) {
                         if (unquoted.length() > 0) {
                             endColumn();
                         }
                         handleUnquoted(unquoted);
                         endRow();
                         consumeNewLines(reader);
                     } else {
                         unquoted.append((char) c);
                     }
                     lastC = c;
                     c = read(reader);
                 }
             } catch (HitMarkLimitException e) {
                 hitMarkLimit = true;
             } catch (UnsurprisingEOF e) {
                 //totally ignore
             } catch (EOFException e) {
                 //the consume* throw this to avoid
                 //having to check -1 every time and
                 //having to rely on potentially wonky
                 //inputstreams not consistently returning -1
                 //after hitting EOF and returning the first -1.
                 //Yes.  That's a thing.
                 eof = true;
             } finally {
                 r.reset();
             }
             //if you've hit the marklimit or an eof on a truncated file
             //don't add the last row's info
             if (!hitMarkLimit && !eof && lastC != NEW_LINE && lastC != CARRIAGE_RETURN) {
                 handleUnquoted(unquoted);
                 endColumn();
                 endRow();
             }
             return calcResult();
         }

         private CSVResult calcResult() {
             double confidence = getConfidence();
             MediaType mediaType = TextAndCSVParser.CSV;
             if (delimiter == '\t') {
                 mediaType = TextAndCSVParser.TSV;
             }
             return new CSVResult(confidence, mediaType, delimiter);
         }

         private void handleUnquoted(StringBuilder unquoted) {
             if (unquoted.length() > 0) {
                 unquoted(unquoted.toString());
                 unquoted.setLength(0);
             }
         }

         void consumeSpaceCharacters(PushbackReader reader) throws IOException {
             int c = read(reader);
             while (c == SPACE) {
                 c = read(reader);
             }
             if (c == EOF) {
                 throw new UnsurprisingEOF();
             }
             unread(reader, c);
         }


         /**
          * @param reader
          * @param quoteCharacter
          * @return whether or not this was a correctly encapsulated cell
          * @throws UnsurprisingEOF if the file ended immediately after the close quote
          * @throws EOFException    if the file ended in the middle of the encapsulated section
          * @throws IOException     on other IOExceptions
          */
         boolean consumeQuoted(PushbackReader reader, int quoteCharacter) throws IOException {
             //this currently assumes excel "escaping" of double quotes:
             //'the " quick' -> "the "" quick"
             //we can make this more interesting later with other
             //escaping options
             int c = read(reader);
             while (c != -1) {
                 if (c == quoteCharacter) {
                     int nextC = read(reader);
                     if (nextC == EOF) {
                         encapsulated++;
                         endColumn();
                         throw new UnsurprisingEOF();
                     } else if (nextC != quoteCharacter) {
                         encapsulated++;
                         endColumn();
                         unread(reader, nextC);
                         consumeSpaceCharacters(reader);
                         //now make sure that the next character is eof, \r\n
                         //or a delimiter
                         nextC = read(reader);
                         if (nextC == EOF) {
                             throw new UnsurprisingEOF();
                         } else if (nextC == NEW_LINE || nextC == CARRIAGE_RETURN) {
                             unread(reader, nextC);
                             return true;
                         } else if (nextC != delimiter) {
                             unread(reader, nextC);
                             return false;
                         }
                         unread(reader, nextC);
                         return true;
                     }
                 }
                 c = read(reader);
             }
             throw new EOFException();
         }

         private int read(PushbackReader reader) throws IOException {
             if (charsRead >= markLimit - 1) {
                 throw new HitMarkLimitException();
             }
             int c = reader.read();
             if (c == EOF) {
                 return EOF;
             }
             charsRead++;
             return c;
         }

         private void unread(PushbackReader reader, int c) throws IOException {
             if (c != EOF) {
                 reader.unread(c);
                 charsRead--;
             }
         }

         //consume all consecutive '\r\n' in any order
         void consumeNewLines(PushbackReader reader) throws IOException {
             int c = read(reader);
             while (c == NEW_LINE || c == CARRIAGE_RETURN) {
                 c = read(reader);
             }
             if (c == EOF) {
                 throw new EOFException();
             }
             unread(reader, c);
             return;
         }


         void endColumn() {
             colCount++;
         }

         void endRow() {
             MutableInt cnt = rowLengthCounts.get(colCount);
             if (cnt == null) {
                 cnt = new MutableInt(1);
                 rowLengthCounts.put(colCount, cnt);
             } else {
                 cnt.increment();
             }
             colCount = 0;
         }

         void unquoted(String string) {
             //TODO -- do some analysis to make sure you don't have
             //large tokens like 2,3,2,3,2,3,
         }

         double getConfidence() {
             double confidence = 0.0f;

             if (parseException) {
                 return -1.0f;
             }
             //TODO -- add tests for long tokens containing
             //other delimiters, e.g. the,quick,brown,fox as a token
             //when testing '\t'
             double colCountConsistencyConf = calculateColumnCountConsistency();
             if (colCountConsistencyConf > -1.0) {
                 confidence = colCountConsistencyConf;
             }
             //the idea is that if there are a bunch of encapsulated
             //cells, then that should outweigh column length inconsistency
             //this particular formula offers a small initial increase
             //that eventually approaches 1.0
             double encapsulatedBonus = 0;
             if (encapsulated > 0) {
                 encapsulatedBonus = 1.0 - (1.0d / Math.pow(encapsulated, 0.2));
             }
             return Math.min(confidence + encapsulatedBonus, 1.0);
         }

         private double calculateColumnCountConsistency() {
             int max = -1;
             int totalRows = 0;
             //find the most common row
             for (Map.Entry<Integer, MutableInt> e : rowLengthCounts.entrySet()) {
                 int numCols = e.getKey();
                 int count = e.getValue().intValue();
                 //require that numCols > 1 so that you had at least
                 //one delimiter in that row
                 if (numCols > 1 && count > max) {
                     max = count;
                 }
                 totalRows += count;
             }
             //if there's not enough info
             if (max < 0 || totalRows < 3) {
                 return 0.0;
             }

             //TODO: convert this to continuous vs vague heuristic step function
             double consistency = (double) max / (double) totalRows;
             return ((1d - (1d / Math.pow(totalRows, 0.3))) * consistency);
         }

     }

     private static class CloseShieldReader extends ProxyReader {
         public CloseShieldReader(Reader r) {
             super(r);
         }

         @Override
         public void close() throws IOException {
             //do nothing
         }
     }
 }
	/*
	* 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 "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 org.apache.tika.parser.csv;

	import java.io.BufferedReader;
	import java.io.EOFException;
	import java.io.IOException;
	import java.io.PushbackReader;
	import java.io.Reader;
	import java.util.ArrayList;
	import java.util.Collections;
	import java.util.HashMap;
	import java.util.List;
	import java.util.Map;

	import org.apache.commons.io.input.ProxyReader;

	import org.apache.tika.metadata.Metadata;
	import org.apache.tika.mime.MediaType;

	class CSVSniffer {
	static final int EOF = -1;
	static final int NEW_LINE = '\n';
	static final int CARRIAGE_RETURN = '\r';
	private static final int DEFAULT_MARK_LIMIT = 10000;
	private static final double DEFAULT_MIN_CONFIDENCE = 0.50;
	private static final int PUSH_BACK = 2;
	private static final int SPACE = ' ';

	private final char[] delimiters;
	private final int markLimit;
	private final double minConfidence;

	CSVSniffer(char[] delimiters) {
	this(DEFAULT_MARK_LIMIT, delimiters, DEFAULT_MIN_CONFIDENCE);
	}

	CSVSniffer(int markLimit, char[] delimiters, double minConfidence) {
	this.markLimit = markLimit;
	this.delimiters = delimiters;
	this.minConfidence = minConfidence;
	}

	List<CSVResult> sniff(Reader reader) throws IOException {
	if (!reader.markSupported()) {
	reader = new BufferedReader(reader);
	}
	List<CSVResult> ret = new ArrayList<>();
	for (char delimiter : delimiters) {
	reader.mark(markLimit);
	try {
	CSVResult result = new Snifflet(delimiter).sniff(reader);
	ret.add(result);
	} finally {
	reader.reset();
	}
	}
	Collections.sort(ret);
	return ret;
	}

	/**
	* @param reader
	* @param metadata
	* @return the best result given the detection results or {@link CSVResult#TEXT}
	* if the confidence is not above a threshold.
	* @throws IOException
	*/
	CSVResult getBest(Reader reader, Metadata metadata) throws IOException {
	//TODO: take into consideration the filename. Perhaps require
	//a higher confidence if detection contradicts filename?
	List<CSVResult> results = sniff(reader);
	if (results == null \|\| results.size() == 0) {
	return CSVResult.TEXT;
	}
	CSVResult bestResult = results.get(0);
	if (bestResult.getConfidence() < minConfidence) {
	return CSVResult.TEXT;
	}
	return bestResult;
	}

	private static class UnsurprisingEOF extends EOFException {

	}

	private static class HitMarkLimitException extends EOFException {

	}

	private static class MutableInt {
	int i;

	MutableInt(int i) {
	this.i = i;
	}

	void increment() {
	i++;
	}

	int intValue() {
	return i;
	}
	}

	//inner class that tests a single hypothesis/combination
	//of parameters for delimiter and quote character
	//this will throw an EOF before reading beyond the
	//markLimit number of characters (not bytes!)
	private class Snifflet {

	private final char delimiter;

	//hardcode this for now
	private final char quoteCharacter = '"';

	Map<Integer, MutableInt> rowLengthCounts = new HashMap<>();
	int charsRead = 0;
	int colCount = 0;
	int encapsulated = 0; //number of cells that are encapsulated in dquotes (for now)
	boolean parseException = false;

	public Snifflet(char delimiter) {
	this.delimiter = delimiter;
	}

	CSVResult sniff(Reader r) throws IOException {
	boolean eof = false;
	boolean hitMarkLimit = false;
	int lastC = -1;
	StringBuilder unquoted = new StringBuilder();
	try (PushbackReader reader = new PushbackReader(new CloseShieldReader(r), PUSH_BACK)) {
	int c = read(reader);
	while (c != EOF) {
	if (c == quoteCharacter) {
	handleUnquoted(unquoted);
	//test to make sure there isn't an unencapsulated quote character
	// in the middle of a cell
	if (lastC > -1 && lastC != delimiter && lastC != NEW_LINE &&
	lastC != CARRIAGE_RETURN) {
	parseException = true;
	return calcResult();
	}
	//TODO: test to make sure cell doesn't start with escaped
	// ""the quick brown cat"
	boolean correctlyEncapsulated = consumeQuoted(reader, quoteCharacter);
	if (!correctlyEncapsulated) {
	parseException = true;
	return calcResult();
	}
	} else if (c == delimiter) {
	handleUnquoted(unquoted);
	endColumn();
	consumeSpaceCharacters(reader);
	} else if (c == NEW_LINE \|\| c == CARRIAGE_RETURN) {
	if (unquoted.length() > 0) {
	endColumn();
	}
	handleUnquoted(unquoted);
	endRow();
	consumeNewLines(reader);
	} else {
	unquoted.append((char) c);
	}
	lastC = c;
	c = read(reader);
	}
	} catch (HitMarkLimitException e) {
	hitMarkLimit = true;
	} catch (UnsurprisingEOF e) {
	//totally ignore
	} catch (EOFException e) {
	//the consume* throw this to avoid
	//having to check -1 every time and
	//having to rely on potentially wonky
	//inputstreams not consistently returning -1
	//after hitting EOF and returning the first -1.
	//Yes. That's a thing.
	eof = true;
	} finally {
	r.reset();
	}
	//if you've hit the marklimit or an eof on a truncated file
	//don't add the last row's info
	if (!hitMarkLimit && !eof && lastC != NEW_LINE && lastC != CARRIAGE_RETURN) {
	handleUnquoted(unquoted);
	endColumn();
	endRow();
	}
	return calcResult();
	}

	private CSVResult calcResult() {
	double confidence = getConfidence();
	MediaType mediaType = TextAndCSVParser.CSV;
	if (delimiter == '\t') {
	mediaType = TextAndCSVParser.TSV;
	}
	return new CSVResult(confidence, mediaType, delimiter);
	}

	private void handleUnquoted(StringBuilder unquoted) {
	if (unquoted.length() > 0) {
	unquoted(unquoted.toString());
	unquoted.setLength(0);
	}
	}

	void consumeSpaceCharacters(PushbackReader reader) throws IOException {
	int c = read(reader);
	while (c == SPACE) {
	c = read(reader);
	}
	if (c == EOF) {
	throw new UnsurprisingEOF();
	}
	unread(reader, c);
	}


	/**
	* @param reader
	* @param quoteCharacter
	* @return whether or not this was a correctly encapsulated cell
	* @throws UnsurprisingEOF if the file ended immediately after the close quote
	* @throws EOFException if the file ended in the middle of the encapsulated section
	* @throws IOException on other IOExceptions
	*/
	boolean consumeQuoted(PushbackReader reader, int quoteCharacter) throws IOException {
	//this currently assumes excel "escaping" of double quotes:
	//'the " quick' -> "the "" quick"
	//we can make this more interesting later with other
	//escaping options
	int c = read(reader);
	while (c != -1) {
	if (c == quoteCharacter) {
	int nextC = read(reader);
	if (nextC == EOF) {
	encapsulated++;
	endColumn();
	throw new UnsurprisingEOF();
	} else if (nextC != quoteCharacter) {
	encapsulated++;
	endColumn();
	unread(reader, nextC);
	consumeSpaceCharacters(reader);
	//now make sure that the next character is eof, \r\n
	//or a delimiter
	nextC = read(reader);
	if (nextC == EOF) {
	throw new UnsurprisingEOF();
	} else if (nextC == NEW_LINE \|\| nextC == CARRIAGE_RETURN) {
	unread(reader, nextC);
	return true;
	} else if (nextC != delimiter) {
	unread(reader, nextC);
	return false;
	}
	unread(reader, nextC);
	return true;
	}
	}
	c = read(reader);
	}
	throw new EOFException();
	}

	private int read(PushbackReader reader) throws IOException {
	if (charsRead >= markLimit - 1) {
	throw new HitMarkLimitException();
	}
	int c = reader.read();
	if (c == EOF) {
	return EOF;
	}
	charsRead++;
	return c;
	}

	private void unread(PushbackReader reader, int c) throws IOException {
	if (c != EOF) {
	reader.unread(c);
	charsRead--;
	}
	}

	//consume all consecutive '\r\n' in any order
	void consumeNewLines(PushbackReader reader) throws IOException {
	int c = read(reader);
	while (c == NEW_LINE \|\| c == CARRIAGE_RETURN) {
	c = read(reader);
	}
	if (c == EOF) {
	throw new EOFException();
	}
	unread(reader, c);
	return;
	}


	void endColumn() {
	colCount++;
	}

	void endRow() {
	MutableInt cnt = rowLengthCounts.get(colCount);
	if (cnt == null) {
	cnt = new MutableInt(1);
	rowLengthCounts.put(colCount, cnt);
	} else {
	cnt.increment();
	}
	colCount = 0;
	}

	void unquoted(String string) {
	//TODO -- do some analysis to make sure you don't have
	//large tokens like 2,3,2,3,2,3,
	}

	double getConfidence() {
	double confidence = 0.0f;

	if (parseException) {
	return -1.0f;
	}
	//TODO -- add tests for long tokens containing
	//other delimiters, e.g. the,quick,brown,fox as a token
	//when testing '\t'
	double colCountConsistencyConf = calculateColumnCountConsistency();
	if (colCountConsistencyConf > -1.0) {
	confidence = colCountConsistencyConf;
	}
	//the idea is that if there are a bunch of encapsulated
	//cells, then that should outweigh column length inconsistency
	//this particular formula offers a small initial increase
	//that eventually approaches 1.0
	double encapsulatedBonus = 0;
	if (encapsulated > 0) {
	encapsulatedBonus = 1.0 - (1.0d / Math.pow(encapsulated, 0.2));
	}
	return Math.min(confidence + encapsulatedBonus, 1.0);
	}

	private double calculateColumnCountConsistency() {
	int max = -1;
	int totalRows = 0;
	//find the most common row
	for (Map.Entry<Integer, MutableInt> e : rowLengthCounts.entrySet()) {
	int numCols = e.getKey();
	int count = e.getValue().intValue();
	//require that numCols > 1 so that you had at least
	//one delimiter in that row
	if (numCols > 1 && count > max) {
	max = count;
	}
	totalRows += count;
	}
	//if there's not enough info
	if (max < 0 \|\| totalRows < 3) {
	return 0.0;
	}

	//TODO: convert this to continuous vs vague heuristic step function
	double consistency = (double) max / (double) totalRows;
	return ((1d - (1d / Math.pow(totalRows, 0.3))) * consistency);
	}

	}

	private static class CloseShieldReader extends ProxyReader {
	public CloseShieldReader(Reader r) {
	super(r);
	}

	@Override
	public void close() throws IOException {
	//do nothing
	}
	}
	}