Copyright (c) 2000, 2018 IBM Corporation and others.
This program and the accompanying materials
are made available under the terms of the Eclipse Public License 2.0
which accompanies this distribution, and is available at
https://www.eclipse.org/legal/epl-2.0/
SPDX-License-Identifier: EPL-2.0
Contributors:
    IBM Corporation - initial API and implementation
/*******************************************************************************
 * Copyright (c) 2000, 2018 IBM Corporation and others.
 *
 * This program and the accompanying materials
 * are made available under the terms of the Eclipse Public License 2.0
 * which accompanies this distribution, and is available at
 * https://www.eclipse.org/legal/epl-2.0/
 *
 * SPDX-License-Identifier: EPL-2.0
 *
 * Contributors:
 *     IBM Corporation - initial API and implementation
 *******************************************************************************/
package org.eclipse.jdt.internal.core.index;

import java.io.*;
import java.util.regex.Pattern;

import org.eclipse.jdt.core.compiler.CharOperation;
import org.eclipse.jdt.core.search.*;
import org.eclipse.jdt.internal.compiler.util.HashtableOfObject;
import org.eclipse.jdt.internal.compiler.util.SimpleSet;
import org.eclipse.jdt.internal.core.search.indexing.ReadWriteMonitor;

An Index maps document names to their referenced words in various categories.

Queries can search a single category or several at the same time.

Indexes are not synchronized structures and should only be queried/updated one at a time.
/**
 * An <code>Index</code> maps document names to their referenced words in various categories.
 * <p>
 * Queries can search a single category or several at the same time.
 * </p>
 * Indexes are not synchronized structures and should only be queried/updated one at a time.
 */
public class Index {

public String containerPath;
public ReadWriteMonitor monitor;

// Separator to use after the container path
static final char DEFAULT_SEPARATOR = '/';
public char separator = DEFAULT_SEPARATOR;
static final char JAR_SEPARATOR = IJavaSearchScope.JAR_FILE_ENTRY_SEPARATOR.charAt(0);

protected DiskIndex diskIndex;
protected MemoryIndex memoryIndex;

Mask used on match rule for indexing.
/**
 * Mask used on match rule for indexing.
 */
static final int MATCH_RULE_INDEX_MASK =
	SearchPattern.R_EXACT_MATCH |
	SearchPattern.R_PREFIX_MATCH |
	SearchPattern.R_PATTERN_MATCH |
	SearchPattern.R_REGEXP_MATCH |
	SearchPattern.R_CASE_SENSITIVE |
	SearchPattern.R_CAMELCASE_MATCH |
	SearchPattern.R_CAMELCASE_SAME_PART_COUNT_MATCH;

public static boolean isMatch(char[] pattern, char[] word, int matchRule) {
	if (pattern == null) return true;
	int patternLength = pattern.length;
	int wordLength = word.length;
	if (patternLength == 0) return matchRule != SearchPattern.R_EXACT_MATCH;
	if (wordLength == 0) return (matchRule & SearchPattern.R_PATTERN_MATCH) != 0 && patternLength == 1 && pattern[0] == '*';

	// need to mask some bits of pattern rule (bug 79790)
	switch(matchRule & MATCH_RULE_INDEX_MASK) {
		case SearchPattern.R_EXACT_MATCH :
			return patternLength == wordLength && CharOperation.equals(pattern, word, false);
		case SearchPattern.R_PREFIX_MATCH :
			return patternLength <= wordLength && CharOperation.prefixEquals(pattern, word, false);
		case SearchPattern.R_REGEXP_MATCH :
			Pattern regexPattern = Pattern.compile(new String(pattern));
			return regexPattern.matcher(new String(word)).matches();
		case SearchPattern.R_PATTERN_MATCH :
			return CharOperation.match(pattern, word, false);
		case SearchPattern.R_CAMELCASE_MATCH:
		// same part count is not activated because index key may have uppercase letters after the type name
		case SearchPattern.R_CAMELCASE_SAME_PART_COUNT_MATCH:
			if (CharOperation.camelCaseMatch(pattern, word, false)) {
				return true;
			}
			return patternLength <= wordLength && CharOperation.prefixEquals(pattern, word, false);
		case SearchPattern.R_EXACT_MATCH | SearchPattern.R_CASE_SENSITIVE :
			return pattern[0] == word[0] && patternLength == wordLength && CharOperation.equals(pattern, word);
		case SearchPattern.R_PREFIX_MATCH | SearchPattern.R_CASE_SENSITIVE :
			return pattern[0] == word[0] && patternLength <= wordLength && CharOperation.prefixEquals(pattern, word);
		case SearchPattern.R_PATTERN_MATCH | SearchPattern.R_CASE_SENSITIVE :
			return CharOperation.match(pattern, word, true);
		case SearchPattern.R_CAMELCASE_MATCH | SearchPattern.R_CASE_SENSITIVE :
		// same part count is not activated because index key may have uppercase letters after the type name
		case SearchPattern.R_CAMELCASE_SAME_PART_COUNT_MATCH | SearchPattern.R_CASE_SENSITIVE :
			return (pattern[0] == word[0] && CharOperation.camelCaseMatch(pattern, word, false));
	}
	return false;
}


public Index(IndexLocation location, String containerPath, boolean reuseExistingFile) throws IOException {
	this.containerPath = containerPath;
	this.monitor = new ReadWriteMonitor();

	this.memoryIndex = new MemoryIndex();
	this.diskIndex = new DiskIndex(location);
	this.diskIndex.initialize(reuseExistingFile);
	if (reuseExistingFile) this.separator = this.diskIndex.separator;
}
public void addIndexEntry(char[] category, char[] key, String containerRelativePath) {
	this.memoryIndex.addIndexEntry(category, key, containerRelativePath);
}
public String containerRelativePath(String documentPath) {
	int index = documentPath.indexOf(IJavaSearchScope.JAR_FILE_ENTRY_SEPARATOR);
	if (index == -1) {
		index = this.containerPath.length();
		if (documentPath.length() <= index)
			throw new IllegalArgumentException("Document path " + documentPath + " must be relative to " + this.containerPath); //$NON-NLS-1$ //$NON-NLS-2$
	}
	return documentPath.substring(index + 1);
}
public File getIndexFile() {
	return this.diskIndex == null ? null : this.diskIndex.indexLocation.getIndexFile();
}
public IndexLocation getIndexLocation() {
	return this.diskIndex == null ? null : this.diskIndex.indexLocation;
}
public long getIndexLastModified() {
	return this.diskIndex == null? -1 : this.diskIndex.indexLocation.lastModified();
}
public boolean hasChanged() {
	return this.memoryIndex.hasChanged();
}
Returns the entries containing the given key in a group of categories, or null if no matches are found.
The matchRule dictates whether its an exact, prefix or pattern match, as well as case sensitive or insensitive.
If the key is null then all entries in specified categories are returned.
/**
 * Returns the entries containing the given key in a group of categories, or null if no matches are found.
 * The matchRule dictates whether its an exact, prefix or pattern match, as well as case sensitive or insensitive.
 * If the key is null then all entries in specified categories are returned.
 */
public EntryResult[] query(char[][] categories, char[] key, int matchRule) throws IOException {
	if (this.memoryIndex.shouldMerge() && this.monitor.exitReadEnterWrite()) {
		try {
			save();
		} finally {
			this.monitor.exitWriteEnterRead();
		}
	}

	HashtableOfObject results;
	int rule = matchRule & MATCH_RULE_INDEX_MASK;
	if (this.memoryIndex.hasChanged()) {
		results = this.diskIndex.addQueryResults(categories, key, rule, this.memoryIndex);
		results = this.memoryIndex.addQueryResults(categories, key, rule, results);
	} else {
		results = this.diskIndex.addQueryResults(categories, key, rule, null);
	}
	if (results == null) return null;

	EntryResult[] entryResults = new EntryResult[results.elementSize];
	int count = 0;
	Object[] values = results.valueTable;
	for (int i = 0, l = values.length; i < l; i++) {
		EntryResult result = (EntryResult) values[i];
		if (result != null)
			entryResults[count++] = result;
	}
	return entryResults;
}
Returns the document names that contain the given substring, if null then returns all of them.
/**
 * Returns the document names that contain the given substring, if null then returns all of them.
 */
public String[] queryDocumentNames(String substring) throws IOException {
	SimpleSet results;
	if (this.memoryIndex.hasChanged()) {
		results = this.diskIndex.addDocumentNames(substring, this.memoryIndex);
		this.memoryIndex.addDocumentNames(substring, results);
	} else {
		results = this.diskIndex.addDocumentNames(substring, null);
	}
	if (results.elementSize == 0) return null;

	String[] documentNames = new String[results.elementSize];
	int count = 0;
	Object[] paths = results.values;
	for (int i = 0, l = paths.length; i < l; i++)
		if (paths[i] != null)
			documentNames[count++] = (String) paths[i];
	return documentNames;
}
public void remove(String containerRelativePath) {
	this.memoryIndex.remove(containerRelativePath);
}
Reset memory and disk indexes.
Throws:
IOException – /**
 * Reset memory and disk indexes.
 * 
 * @throws IOException
 */
public void reset() throws IOException {
	this.memoryIndex = new MemoryIndex();
	this.diskIndex = new DiskIndex(this.diskIndex.indexLocation);
	this.diskIndex.initialize(false/*do not reuse the index file*/);
}
public void save() throws IOException {
	// must own the write lock of the monitor
	if (!hasChanged()) return;

	this.diskIndex.separator = this.separator;
	this.diskIndex = this.diskIndex.mergeWith(this.memoryIndex);
	this.memoryIndex = new MemoryIndex();
}
public void startQuery() {
	if (this.diskIndex != null)
		this.diskIndex.startQuery();
}
public void stopQuery() {
	if (this.diskIndex != null)
		this.diskIndex.stopQuery();
}
@Override
public String toString() {
	return "Index for " + this.containerPath; //$NON-NLS-1$
}
public boolean isIndexForJar()
{
	return this.separator == JAR_SEPARATOR;
}
}