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 * 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.
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/* $Id$ */

package org.apache.fop.complexscripts.fonts;

import org.apache.fop.complexscripts.util.GlyphSequence;
import org.apache.fop.complexscripts.util.ScriptContextTester;

// CSOFF: LineLengthCheck

The GlyphSubstitutionSubtable implements an abstract base of a glyph substitution subtable,
providing a default implementation of the GlyphSubstitution interface.
This work was originally authored by Glenn Adams (gadams@apache.org).
/**
 * <p>The <code>GlyphSubstitutionSubtable</code> implements an abstract base of a glyph substitution subtable,
 * providing a default implementation of the <code>GlyphSubstitution</code> interface.</p>
 *
 * <p>This work was originally authored by Glenn Adams (gadams@apache.org).</p>
 */
public abstract class GlyphSubstitutionSubtable extends GlyphSubtable implements GlyphSubstitution {

    private static final GlyphSubstitutionState STATE = new GlyphSubstitutionState();

    
Instantiate a GlyphSubstitutionSubtable.
Params:
id – subtable identifier
sequence – subtable sequence
flags – subtable flags
format – subtable format
coverage – subtable coverage table/**
     * Instantiate a <code>GlyphSubstitutionSubtable</code>.
     * @param id subtable identifier
     * @param sequence subtable sequence
     * @param flags subtable flags
     * @param format subtable format
     * @param coverage subtable coverage table
     */
    protected GlyphSubstitutionSubtable(String id, int sequence, int flags, int format, GlyphCoverageTable coverage) {
        super(id, sequence, flags, format, coverage);
    }

    
{@inheritDoc} /** {@inheritDoc} */
    public int getTableType() {
        return GlyphTable.GLYPH_TABLE_TYPE_SUBSTITUTION;
    }

    
{@inheritDoc} /** {@inheritDoc} */
    public String getTypeName() {
        return GlyphSubstitutionTable.getLookupTypeName(getType());
    }

    
{@inheritDoc} /** {@inheritDoc} */
    public boolean isCompatible(GlyphSubtable subtable) {
        return subtable instanceof GlyphSubstitutionSubtable;
    }

    
{@inheritDoc} /** {@inheritDoc} */
    public boolean usesReverseScan() {
        return false;
    }

    
{@inheritDoc} /** {@inheritDoc} */
    public boolean substitute(GlyphSubstitutionState ss) {
        return false;
    }

    
Apply substitutions using specified state and subtable array. For each position in input sequence,
apply subtables in order until some subtable applies or none remain. If no subtable applied or no
input was consumed for a given position, then apply default action (copy input glyph and advance).
If sequenceIndex is non-negative, then apply subtables only when current position
matches sequenceIndex in relation to the starting position. Furthermore, upon
successful application at sequenceIndex, then apply default action for all remaining
glyphs in input sequence.
Params:
ss – substitution state
sta – array of subtables to apply
sequenceIndex – if non negative, then apply subtables only at specified sequence index
Returns:
output glyph sequence/**
     * Apply substitutions using specified state and subtable array. For each position in input sequence,
     * apply subtables in order until some subtable applies or none remain. If no subtable applied or no
     * input was consumed for a given position, then apply default action (copy input glyph and advance).
     * If <code>sequenceIndex</code> is non-negative, then apply subtables only when current position
     * matches <code>sequenceIndex</code> in relation to the starting position. Furthermore, upon
     * successful application at <code>sequenceIndex</code>, then apply default action for all remaining
     * glyphs in input sequence.
     * @param ss substitution state
     * @param sta array of subtables to apply
     * @param sequenceIndex if non negative, then apply subtables only at specified sequence index
     * @return output glyph sequence
     */
    public static final GlyphSequence substitute(GlyphSubstitutionState ss, GlyphSubstitutionSubtable[] sta, int sequenceIndex) {
        int sequenceStart = ss.getPosition();
        boolean appliedOneShot = false;
        while (ss.hasNext()) {
            boolean applied = false;
            if (!appliedOneShot && ss.maybeApplicable()) {
                for (int i = 0, n = sta.length; !applied && (i < n); i++) {
                    if (sequenceIndex < 0) {
                        applied = ss.apply(sta [ i ]);
                    } else if (ss.getPosition() == (sequenceStart + sequenceIndex)) {
                        applied = ss.apply(sta [ i ]);
                        if (applied) {
                            appliedOneShot = true;
                        }
                    }
                }
            }
            if (!applied || !ss.didConsume()) {
                ss.applyDefault();
            }
            ss.next();
        }
        return ss.getOutput();
    }

    
Apply substitutions.
Params:
gs – input glyph sequence
script – tag
language – tag
feature – tag
sta – subtable array
sct – script context tester
Returns:
output glyph sequence/**
     * Apply substitutions.
     * @param gs input glyph sequence
     * @param script tag
     * @param language tag
     * @param feature tag
     * @param sta subtable array
     * @param sct script context tester
     * @return output glyph sequence
     */
    public static final GlyphSequence substitute(GlyphSequence gs, String script, String language, String feature, GlyphSubstitutionSubtable[] sta, ScriptContextTester sct) {
        synchronized (STATE) {
            return substitute(STATE.reset(gs, script, language, feature, sct), sta, -1);
        }
    }

}