org.eclipse.opencert.userguidance/src/org/eclipse/opencert/userguidance/labelparser/LabelParserUtil.java

/*******************************************************************************
 * Copyright (c) 2016 KPIT Technologies.
 *
 * All rights reserved. This program and the accompanying materials
 * are made available under the terms of the Eclipse Public License v2.0
 * which accompanies this distribution, and is available at
 * https://www.eclipse.org/org/documents/epl-2.0/EPL-2.0.html
 *
 * SPDX-License-Identifier: EPL-2.0
 *
 * Contributors:
 *   Jan Mauersberger- initial API and implementation
 *   Sascha Baumgart- initial API and implementation
 *******************************************************************************/
package org.eclipse.opencert.userguidance.labelparser;

import java.util.ArrayList;
import java.util.List;

import org.antlr.v4.runtime.ANTLRInputStream;
import org.antlr.v4.runtime.CommonTokenStream;
import org.antlr.v4.runtime.RecognitionException;
import org.antlr.v4.runtime.tree.ParseTree;
import org.antlr.v4.runtime.tree.TerminalNode;
import org.eclipse.opencert.userguidance.labelparser.generated.LabelLexer;
import org.eclipse.opencert.userguidance.labelparser.generated.LabelParser;
import org.eclipse.opencert.userguidance.labelparser.generated.LabelParser.ItemContext;
import org.eclipse.opencert.userguidance.labelparser.generated.LabelParser.ItembodyContext;
import org.eclipse.opencert.userguidance.labelparser.generated.LabelParser.TextContext;
import org.eclipse.opencert.userguidance.labelparser.tokens.HighlightItem;
import org.eclipse.opencert.userguidance.labelparser.tokens.HighlightItem.ItemBodyType;
import org.eclipse.opencert.userguidance.labelparser.tokens.HighlightItem.ItemHeaderType;
import org.eclipse.opencert.userguidance.labelparser.tokens.TextToken;
import org.eclipse.opencert.userguidance.labelparser.tokens.Token;

public class LabelParserUtil {
	public static List<Token> parse(String input) {
		List<Token> result = new ArrayList<Token>();
		if (input.length() == 0) {
			return result;
		}

		ANTLRInputStream stream = new ANTLRInputStream(input);
		LabelLexer lexer = new LabelLexer(stream);
		CommonTokenStream tokens = new CommonTokenStream(lexer);
		LabelParser parser = new LabelParser(tokens);

		TextContext tree = null;
		try {
			tree = parser.text();
		} catch (RecognitionException e) {
			return result;
		}
		result = process(tree);

		return result;
	}

	private static List<Token> process(TextContext tree) {
		List<Token> result = new ArrayList<Token>();

		// The total length of all previously processed tokens
		int position = 0;

		for (int i = 0; i < tree.getChildCount(); i++) {
			ParseTree child = tree.getChild(i);
			if (child instanceof ItemContext) {
				ItemContext itemContext = (ItemContext) child;

				if (itemContext.getChildCount() != 3) {
					throw new IllegalArgumentException(
							"Parser error: The token '" + itemContext.getText()
									+ "' should have 3 child tokens.");
				}

				// Need to populate the following variables
				String rawItemString = null;
				String body = null;
				String representation = null;
				ItemHeaderType headerType = null;
				ItemBodyType bodyType = null;
				int startIndex = -1;

				// Get rawItemString and startIndex
				rawItemString = itemContext.getText();
				startIndex = itemContext.getStart().getStartIndex();

				// Get headerType
				TerminalNode headerTerminalNode = (TerminalNode) itemContext
						.getChild(0);
				String headerString = headerTerminalNode.getText();
				headerType = ItemHeaderType.parse(headerString);

				// Get bodyType
				ItembodyContext bodyNode = (ItembodyContext) itemContext
						.getChild(2);
				int bodyChildCount = bodyNode.getChildCount();
				if (bodyChildCount == 0) {
					continue;
				}
				if (bodyNode.getChild(0).getText().equals("\"")
						&& bodyNode.getChild(bodyChildCount - 1).getText()
								.equals("\"")) {
					bodyType = ItemBodyType.doublequoted;
				} else if (bodyNode.getChild(0).getText().equals("'")
						&& bodyNode.getChild(bodyChildCount - 1).getText()
								.equals("'")) {
					bodyType = ItemBodyType.singlequoted;
				} else {
					bodyType = ItemBodyType.unquoted;
				}

				// Get body and representation
				StringBuilder bodyBuilder = new StringBuilder();
				int firstString = bodyType == ItemBodyType.unquoted ? 0 : 1;
				int lastString = bodyType == ItemBodyType.unquoted ? bodyNode
						.getChildCount() : bodyNode.getChildCount() - 1;
				for (int j = firstString; j < lastString; j++) {
					// Avoid appending parsing error messages
					if (!bodyNode.getChild(j).getText().startsWith("<missing ")) {
						bodyBuilder.append(bodyNode.getChild(j).getText());
					}
				}
				String bodyRawText = bodyBuilder.toString();

				if (bodyRawText.contains("|")) {
					int pipeIndex = bodyRawText.indexOf('|');
					body = bodyRawText.substring(0, pipeIndex);
					representation = bodyRawText.substring(pipeIndex + 1);
				} else {
					body = bodyRawText;
					representation = bodyRawText;
				}

				HighlightItem item = new HighlightItem(rawItemString, body,
						representation, headerType, bodyType, startIndex);

				result.add(item);
				position += item.getStartIndex() + item.getRawString().length();
			}

			if (child instanceof TerminalNode) {
				TerminalNode terminalNode = (TerminalNode) child;
				String text = terminalNode.getText();
				TextToken textToken = new TextToken(text, position);
				result.add(textToken);
				position += textToken.getRepresentation().length();
			}

		}

		return result;
	}
}