Merge pull request #12 from kthoms/bug443574-fsa-exists

[bug 443574] Added interface IFileSystemAccessExtension4

plugins/org.eclipse.xtext/src/org/eclipse/xtext/generator/AbstractFileSystemAccess2.java

@@ -7,18 +7,20 @@
  *******************************************************************************/
 package org.eclipse.xtext.generator;
 
+import java.io.IOException;
 import java.io.InputStream;
 
 import org.eclipse.emf.ecore.resource.Resource;
+import org.eclipse.xtext.util.RuntimeIOException;
 
 /**
- * 
- * Abstract base class for file system access supporting {@link IFileSystemAccessExtension3}.
- * 
+ *
+ * Abstract base class for file system access supporting {@link IFileSystemAccessExtension3} and {@link IFileSystemAccessExtension4}.
+ *
  * @author Sven Efftinge - Initial contribution and API
  * @since 2.4
  */
-public abstract class AbstractFileSystemAccess2 extends AbstractFileSystemAccess implements IFileSystemAccessExtension3 {
+public abstract class AbstractFileSystemAccess2 extends AbstractFileSystemAccess implements IFileSystemAccessExtension3, IFileSystemAccessExtension4 {
 
 	/**
 	 * @since 2.4
@@ -44,17 +46,39 @@ public abstract class AbstractFileSystemAccess2 extends AbstractFileSystemAccess
 		return readTextFile(fileName, DEFAULT_OUTPUT);
 	}
 
-	
+
 	/**
 	 * Sets the context to further configure this file system access instance.
-	 * 
-	 * @param context - a context from which project configuration can be obtained. Supported context types 
-	 * 	depend on the concrete implementation, but {@link Resource} is usually a good fit. 
-	 * 
+	 *
+	 * @param context - a context from which project configuration can be obtained. Supported context types
+	 * 	depend on the concrete implementation, but {@link Resource} is usually a good fit.
+	 *
 	 * @since 2.8
 	 */
 	public void setContext(Object context) {
 		// do nothing
 	}
-	
+
+	/**
+	 * {@inheritDoc}
+	 * @since 2.9
+	 */
+	@Override
+	public boolean isFile(String path, String outputConfigurationName) throws RuntimeIOException {
+		InputStream is = null;
+		try {
+			is = readBinaryFile(path, outputConfigurationName);
+			if (is != null) {
+				try {
+					is.close();
+				} catch (IOException e) {
+					throw new RuntimeIOException(e);
+				}
+			}
+			return is!=null; // no exception => file exists
+		} catch (RuntimeIOException e) {
+			return false;
+		}
+	}
+
 }

plugins/org.eclipse.xtext/src/org/eclipse/xtext/generator/IFileSystemAccessExtension4.java

@@ -0,0 +1,28 @@
+/*******************************************************************************
+ * Copyright (c) 2015 itemis AG (http://www.itemis.eu) and others.
+ * 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
+ *******************************************************************************/
+package org.eclipse.xtext.generator;
+
+import org.eclipse.xtext.util.RuntimeIOException;
+
+/**
+ * This interface extends {@link IFileSystemAccess} with the capability to check files for existence.
+ *
+ * @author Karsten Thoms - Initial contribution and API
+ * @since 2.9
+ */
+public interface IFileSystemAccessExtension4 {
+
+	/**
+	 * Tests whether the file exists at the location denoted by the output configuration.
+	 * @param path using '/' as path separator
+	 * @param outputConfigurationName the name of the output configuration
+	 * @return <code>true</code> when the file at the given path exists and is a normal file. Will return <code>false</code> when
+	 * the path belongs to a directory.
+	 */
+	boolean isFile (String path, String outputConfigurationName) throws RuntimeIOException;
+}

plugins/org.eclipse.xtext/src/org/eclipse/xtext/generator/JavaIoFileSystemAccess.java

@@ -235,4 +235,13 @@ public class JavaIoFileSystemAccess extends AbstractFileSystemAccess2 {
 			throw new RuntimeIOException(e);
 		}
 	}
+
+	/**
+	 * {@inheritDoc}
+	 */
+	@Override
+	public boolean isFile(String path, String outputConfigurationName) throws RuntimeIOException {
+		File file = getFile(path, outputConfigurationName);
+		return file!=null && file.exists() && file.isFile();
+	}
 }

tests/org.eclipse.xtext.tests/src/org/eclipse/xtext/generator/JavaIoFileSystemAccessTest.java

@@ -55,6 +55,8 @@ public class JavaIoFileSystemAccessTest extends Assert {
 
 			binFile = new File(dir, "Y");
 			assertTrue(binFile.exists());
+			assertFalse(fileSystemAccess.isFile("tmp", IFileSystemAccess.DEFAULT_OUTPUT)); // isFile evaluates to false for directories
+			assertTrue(fileSystemAccess.isFile("tmp/Y", IFileSystemAccess.DEFAULT_OUTPUT));
 			assertTrue(binFile.isFile());
 			InputStream stream = fileSystemAccess.readBinaryFile("tmp/Y");
 			try {