StringCharacterScanner.java

/*******************************************************************************
 * Copyright (c) 2012-2017 Codenvy, S.A.
 * All rights reserved. This program and the accompanying materials
 * are made available under the terms of the Eclipse Public License v1.0
 * which accompanies this distribution, and is available at
 * http://www.eclipse.org/legal/epl-v10.html
 *
 * Contributors:
 *   Codenvy, S.A. - initial API and implementation
 *******************************************************************************/
package org.eclipse.che.ide.api.editor.partition;

import java.util.List;

import com.google.gwt.regexp.shared.MatchResult;
import com.google.gwt.regexp.shared.RegExp;

/**
 * Implementation of {@link CharacterScanner} with a String as input.
 */
public class StringCharacterScanner implements CharacterScanner {

    /** The scanned content. */
    private String content;

    /** The offset of the scanner within the content. */
    private int offset = 0;

    /** The delimiters of the document. */
    private List<String> delimiters;

    @Override
    public List<String> getLegalLineDelimiters() {
        return this.delimiters;
    }

    @Override
    public int getColumn() {
        return getColumn(this.offset);
    }

    private int getColumn(int offset) {
        // Bad and slow implementation
        if (offset < 0 || offset > this.content.length()) {
            return -1;
        }
        if (this.delimiters == null || this.delimiters.isEmpty()) {
            return offset;
        }

        final StringBuilder sb = new StringBuilder("[");
        for (final String delimiter: this.delimiters) {
            sb.append("(?:")
              .append(delimiter)
              .append(")");
        }
        sb.append("]");
        final RegExp regexp = RegExp.compile(sb.toString());

        final String split = this.content;
        int currentIndex = 0;
        while (currentIndex < offset) {
            final MatchResult matchResult = regexp.exec(split);
            final int found = matchResult.getIndex();
            if (found < 0) {
                throw new RuntimeException("Invalid index for regexp match");
            }
            if (currentIndex + found > offset) {
                // we're on the same line as offset
                return offset - currentIndex;
            }
            currentIndex = currentIndex + found + 1;
        }
        return -1;
    }

    @Override
    public int read() {
        if (this.offset == this.content.length()) {
            return EOF;
        }
        final int result = this.content.charAt(this.offset);
        this.offset++;
        return result;
    }

    @Override
    public void unread() {
        if (this.offset != 0) {
            this.offset--;
        }// else already at doc start
    }

    public void setLegalLineDelimiters(final List<String> delimiters) {
        this.delimiters = delimiters;
    }

    public void setScannedString(final String content) {
        this.content = content;
        this.offset = 0;
    }
}