/*

* Copyright (c) 2007 Nokia Corporation and/or its subsidiary(-ies). 

* All rights reserved.

* This component and the accompanying materials are made available

* under the terms of "Eclipse Public License v1.0"

* which accompanies this distribution, and is available

* at the URL "http://www.eclipse.org/legal/epl-v10.html".

*

* Initial Contributors:

* Nokia Corporation - initial contribution.

*

* Contributors:

*

* Description:

*

* Parser for function return values

*

*/

package com.nokia.tracebuilder.source;

import java.util.Collections;

import java.util.List;

/**

 * Parser for function return values

 * 

 */

class FunctionReturnValueParser {

	/**

	 * Source parser

	 */

	private SourceParser parser;

	/**

	 * Comparator for source return values

	 */

	private PositionArrayComparator comparator = new PositionArrayComparator();

	/**

	 * Macros representing return statement

	 */

	private List<String> returnExtensions;

	/**

	 * Constructor

	 * 

	 * @param parser

	 *            the source parser

	 */

	FunctionReturnValueParser(SourceParser parser) {

		this.parser = parser;

	}

	/**

	 * Parses the return values of given source context

	 * 

	 * @param context

	 *            the context to be parsed

	 * @param list

	 *            the list of return values

	 */

	void parseReturnValues(SourceContext context, List<SourceReturn> list) {

		String statement = SourceConstants.RETURN;

		try {

			parseReturnValues(context, list, statement);

		} catch (SourceParserException e) {

		}

		if (returnExtensions != null && returnExtensions.size() > 0) {

			for (int i = 0; i < returnExtensions.size(); i++) {

				try {

					parseReturnValues(context, list, returnExtensions.get(i));

				} catch (SourceParserException e) {

				}

			}

			Collections.sort(list, comparator);

		}

		if (context.isVoid()) {

			boolean addToEnd = true;

			// If there were no return statements, the trace is added to end

			// Otherwise the last return statement needs to be checked. If it is

			// at the end of the function, the return trace is not added to

			// the end

			if (!list.isEmpty()) {

				SourceReturn ret = list.get(list.size() - 1);

				SourceIterator itr = parser.createIterator(ret.getOffset()

						+ ret.getLength() + 1, SourceParser.SKIP_ALL);

				try {

					itr.next();

					// If the next character after return statement is the end

					// of function, the return is not added

					if (itr.currentIndex() == context.getOffset()

							+ context.getLength() - 1) {

						addToEnd = false;

					}

				} catch (SourceParserException e) {

					addToEnd = false;

				}

			}

			if (addToEnd) {

				list.add(new SourceReturn(parser, context.getOffset()

						+ context.getLength() - 1, 0));

			}

		}

	}

	/**

	 * Parses the return values of given source context that use the given

	 * return statement

	 * 

	 * @param context

	 *            the context to be parsed

	 * @param list

	 *            the list of return values

	 * @param statement

	 *            the return statement

	 * @throws SourceParserException

	 *             if processing fails

	 */

	private void parseReturnValues(SourceContext context,

			List<SourceReturn> list, String statement)

			throws SourceParserException {

		FunctionReturnValueSearchData data = new FunctionReturnValueSearchData();

		int offset = context.getOffset();

		int end = offset + context.getLength();

		SourceSearch search = parser.startStringSearch(statement, offset, end,

				SourceParser.MATCH_WHOLE_WORD | SourceParser.SKIP_ALL);

		boolean looping = true;

		do {

			data.index = search.findNext();

			if (data.index != -1) {

				data.itr = parser.createIterator(data.index

						+ statement.length(), SourceParser.SKIP_ALL);

				locateReturnStatement(data);

				if (data.endOffset != -1 && data.startOffset != -1) {

					SourceReturn ret = createReturnStatement(data);

					list.add(ret);

				} else {

					// End of return statement missing

					looping = false;

				}

			} else {

				looping = false;

			}

		} while (looping);

	}

	/**

	 * Locates the start and end offsets for the return statement

	 * 

	 * @param data

	 *            the search data

	 * @throws SourceParserException

	 *             if parser fails

	 */

	private void locateReturnStatement(FunctionReturnValueSearchData data)

			throws SourceParserException {

		data.startOffset = -1;

		data.endOffset = -1;

		boolean found = false;

		boolean colonAllowed = false;

		while (data.itr.hasNext() && !found) {

			char c = data.itr.next();

			if (c == ';') {

				data.endOffset = data.itr.previousIndex() + 1;

				found = true;

			} else if (c == '}') {

				found = true;

			} else if (c == '?') {

				colonAllowed = true;

			} else if (c == ':') {

				if (data.itr.hasNext() && data.itr.peek() == ':') {

					// Skips over ::

					c = data.itr.next();

				} else {

					if (colonAllowed) {

						colonAllowed = false;

					} else {

						data.endOffset = data.itr.previousIndex() + 1;

						found = true;

					}

				}

			}

			if (data.startOffset == -1) {

				data.startOffset = data.itr.currentIndex();

			}

		}

	}

	/**

	 * Creates a return statement

	 * 

	 * @param data

	 *            the parser data

	 * @return the new statement

	 * @throws SourceParserException

	 *             if parser fails

	 */

	private SourceReturn createReturnStatement(

			FunctionReturnValueSearchData data) throws SourceParserException {

		SourceReturn ret = new SourceReturn(parser, data.startOffset,

				data.endOffset - data.startOffset);

		if (checkTag(data.startOffset, data.endOffset - data.startOffset)) {

			ret.setTagHazard();

		}

		if (checkPreviousChar(data.index - 1)) {

			ret.setPreviousCharHazard();

		}

		return ret;

	}

	/**

	 * Checks if the tag is hazardous

	 * 

	 * @param start

	 *            start offset

	 * @param length

	 *            tag length

	 * @return true if there is a problem

	 */

	private boolean checkTag(int start, int length) {

		boolean hazard = false;

		boolean previous = false;

		// Function calls and increment / decrement operators are not safe

		for (int i = start; i < start + length && !hazard; i++) {

			char c = parser.getData(i);

			if (c == '(') {

				// If return statement is within brackets, it is not hazardous

				if (i != start || parser.getData(start + length - 1) != ')') {

					hazard = true;

				}

			} else if (c == '?') {

				hazard = true;

			} else if (c == '-' || c == '+') {

				if (previous) {

					hazard = true;

				} else {

					previous = true;

				}

			} else {

				previous = false;

			}

		}

		return hazard;

	}

	/**

	 * Checks if previous character is hazardous

	 * 

	 * @param index

	 *            the index

	 * @return true if hazard, false if not

	 * @throws SourceParserException

	 *             if processing fails

	 */

	private boolean checkPreviousChar(int index) throws SourceParserException {

		boolean hazard = false;

		SourceIterator previtr = parser.createIterator(index,

				SourceParser.SKIP_ALL | SourceParser.BACKWARD_SEARCH);

		char prevchar = previtr.next();

		if (prevchar != ';' && prevchar != '{' && prevchar != '}') {

			hazard = true;

		}

		return hazard;

	}

	/**

	 * Finds the last return statement from the given context

	 * 

	 * @param context

	 *            the context

	 * @return the index to beginning of the return statement

	 */

	int findLast(SourceContext context) {

		String statement = SourceConstants.RETURN;

		int retval = findLast(context, statement);

		if (returnExtensions != null && returnExtensions.size() > 0) {

			int res;

			for (int i = 0; i < returnExtensions.size(); i++) {

				res = findLast(context, returnExtensions.get(i));

				if (res > retval) {

					retval = res;

				}

			}

		}

		if (retval == -1) {

			retval = context.getOffset() + context.getLength();

		}

		return retval;

	}

	/**

	 * Finds the last return statement from the given context

	 * 

	 * @param context

	 *            the context

	 * @param statement

	 *            the statement to be searched

	 * @return the index to beginning of the return statement

	 */

	private int findLast(SourceContext context, String statement) {

		// TODO: Backwards string search

		int start = context.getOffset();

		int end = start + context.getLength();

		SourceSearch search = parser.startStringSearch(statement, start, end,

				SourceParser.MATCH_WHOLE_WORD | SourceParser.SKIP_ALL);

		int index = 0;

		int retval = -1;

		do {

			index = search.findNext();

			if (index != -1) {

				retval = index;

			}

		} while (index != -1);

		return retval;

	}

}