org.eclipse.jdt.junit/src/org/eclipse/jdt/internal/junit/ui/TextualTrace.java

/**
 * 
 */
package org.eclipse.jdt.internal.junit.ui;

import java.io.BufferedReader;
import java.io.IOException;
import java.io.PrintWriter;
import java.io.StringReader;
import java.io.StringWriter;

public class TextualTrace {
	public static final int LINE_TYPE_EXCEPTION = 1;

	public static final int LINE_TYPE_NORMAL = 0;

	public static final int LINE_TYPE_STACKFRAME = 2;

	private final String fTrace;

	public TextualTrace(String trace, String[] filterPatterns) {
		super();
		fTrace = filterStack(trace, filterPatterns);
	}

	public void display(ITraceDisplay display, int maxLabelLength) {
		StringReader stringReader = new StringReader(fTrace);
		BufferedReader bufferedReader = new BufferedReader(stringReader);
		String line;

		try {
			// first line contains the thrown exception
			line = readLine(bufferedReader);
			if (line == null)
				return;

			displayWrappedLine(display, maxLabelLength, line,
					LINE_TYPE_EXCEPTION);

			// the stack frames of the trace
			while ((line = readLine(bufferedReader)) != null) {
				int type = isAStackFrame(line) ? LINE_TYPE_STACKFRAME
						: LINE_TYPE_NORMAL;
				displayWrappedLine(display, maxLabelLength, line, type);
			}
		} catch (IOException e) {
			display.addTraceLine(LINE_TYPE_NORMAL, fTrace);
		}
	}

	private void displayWrappedLine(ITraceDisplay display, int maxLabelLength,
			String line, int type) {
		final int labelLength = line.length();
		if (labelLength < maxLabelLength) {
			display.addTraceLine(type, line);
		} else {
			// workaround for bug 74647: JUnit view truncates
			// failure message
			display.addTraceLine(type, line.substring(0, maxLabelLength));
			int offset = maxLabelLength;
			while (offset < labelLength) {
				int nextOffset = Math.min(labelLength, offset + maxLabelLength);
				display.addTraceLine(LINE_TYPE_NORMAL, line.substring(offset,
						nextOffset));
				offset = nextOffset;
			}
		}
	}

	private boolean filterLine(String[] patterns, String line) {
		String pattern;
		int len;
		for (int i = (patterns.length - 1); i >= 0; --i) {
			pattern = patterns[i];
			len = pattern.length() - 1;
			if (pattern.charAt(len) == '*') {
				// strip trailing * from a package filter
				pattern = pattern.substring(0, len);
			} else if (Character.isUpperCase(pattern.charAt(0))) {
				// class in the default package
				pattern = FailureTrace.FRAME_PREFIX + pattern + '.';
			} else {
				// class names start w/ an uppercase letter after the .
				final int lastDotIndex = pattern.lastIndexOf('.');
				if ((lastDotIndex != -1)
					&& (lastDotIndex != len)
					&& Character.isUpperCase(pattern.charAt(lastDotIndex + 1)))
					pattern += '.'; // append . to a class filter
			}

			if (line.indexOf(pattern) > 0)
				return true;
		}
		return false;
	}

	private String filterStack(String stackTrace, String[] filterPatterns) {
		if (filterPatterns.length == 0 || stackTrace == null)
			return stackTrace;

		StringWriter stringWriter = new StringWriter();
		PrintWriter printWriter = new PrintWriter(stringWriter);
		StringReader stringReader = new StringReader(stackTrace);
		BufferedReader bufferedReader = new BufferedReader(stringReader);

		String line;
		String[] patterns = filterPatterns;
		try {
			while ((line = bufferedReader.readLine()) != null) {
				if (!filterLine(patterns, line))
					printWriter.println(line);
			}
		} catch (IOException e) {
			return stackTrace; // return the stack unfiltered
		}
		return stringWriter.toString();
	}

	private boolean isAStackFrame(String itemLabel) {
		// heuristic for detecting a stack frame - works for JDK
		return itemLabel.indexOf(" at ") >= 0; //$NON-NLS-1$
	}

	private String readLine(BufferedReader bufferedReader) throws IOException {
		String readLine = bufferedReader.readLine();
		return readLine == null ? null : readLine.replace('\t', ' ');
	}
}