org.eclipse.mylyn.internal.wikitext.commonmark.blocks.FencedCodeBlock.java Source code

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Here is the source code for org.eclipse.mylyn.internal.wikitext.commonmark.blocks.FencedCodeBlock.java

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/*******************************************************************************
 * Copyright (c) 2015 David Green.
 * 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:
 *     David Green - initial API and implementation
 *******************************************************************************/

package org.eclipse.mylyn.internal.wikitext.commonmark.blocks;

import static com.google.common.base.Preconditions.checkState;

import java.util.regex.Matcher;
import java.util.regex.Pattern;

import org.eclipse.mylyn.internal.wikitext.commonmark.Line;
import org.eclipse.mylyn.internal.wikitext.commonmark.LinePredicates;
import org.eclipse.mylyn.internal.wikitext.commonmark.LineSequence;
import org.eclipse.mylyn.internal.wikitext.commonmark.ProcessingContext;
import org.eclipse.mylyn.internal.wikitext.commonmark.SourceBlock;
import org.eclipse.mylyn.wikitext.core.parser.Attributes;
import org.eclipse.mylyn.wikitext.core.parser.DocumentBuilder;
import org.eclipse.mylyn.wikitext.core.parser.DocumentBuilder.BlockType;

import com.google.common.base.Predicates;

public class FencedCodeBlock extends SourceBlock {

    private final Pattern openingFencePattern = Pattern
            .compile("(\\s{0,4})(`{3,}|~{3,})\\s*(?:([^\\s~`]+)[^~`]*)?");

    @Override
    public void process(ProcessingContext context, DocumentBuilder builder, LineSequence lineSequence) {
        Matcher matcher = openingFencePattern.matcher(lineSequence.getCurrentLine().getText());
        checkState(matcher.matches());
        String indent = matcher.group(1);
        boolean indentedCodeBlock = indent != null && indent.length() == 4;
        Pattern closingFencePattern = closingFencePattern(matcher);

        Attributes codeAttributes = new Attributes();
        addInfoTextCssClass(codeAttributes, matcher);

        builder.setLocator(lineSequence.getCurrentLine().toLocator());
        builder.beginBlock(BlockType.CODE, codeAttributes);

        if (indentedCodeBlock) {
            outputLine(builder, indent, lineSequence.getCurrentLine());
        }
        lineSequence.advance();
        for (Line line : lineSequence.with(Predicates.not(LinePredicates.matches(closingFencePattern)))) {
            outputLine(builder, indent, line);
        }
        if (indentedCodeBlock && lineSequence.getCurrentLine() != null) {
            outputLine(builder, indent, lineSequence.getCurrentLine());
        }
        lineSequence.advance();

        builder.endBlock();
    }

    private void outputLine(DocumentBuilder builder, String indent, Line line) {
        String text = line.getText();
        text = removeIndent(indent, text);
        builder.characters(text);
        builder.characters("\n");
    }

    private String removeIndent(String indent, String text) {
        if (indent != null && indent.length() > 0) {
            Pattern indentPattern = Pattern.compile("\\s{1," + indent.length() + "}(.*)");
            Matcher matcher = indentPattern.matcher(text);
            if (matcher.matches()) {
                return matcher.group(1);
            }
        }
        return text;
    }

    private Pattern closingFencePattern(Matcher matcher) {
        String fence = matcher.group(2);
        char fenceDelimiter = fence.charAt(0);
        return Pattern.compile("\\s{0,3}" + fenceDelimiter + "{" + fence.length() + ",}\\s*");
    }

    private void addInfoTextCssClass(Attributes codeAttributes, Matcher matcher) {
        String infoText = matcher.group(3);
        if (infoText != null) {
            codeAttributes.setCssClass("language-" + infoText);
        }
    }

    @Override
    public boolean canStart(LineSequence lineSequence) {
        Line line = lineSequence.getCurrentLine();
        return line != null && openingFencePattern.matcher(line.getText()).matches();
    }

    boolean canEnd(Line line, Line startLine) {
        Matcher matcher = openingFencePattern.matcher(startLine.getText());
        checkState(matcher.matches());
        Pattern closingFencePattern = closingFencePattern(matcher);
        return closingFencePattern.matcher(line.getText()).matches();
    }

}