Bug 486834: Language service doesn't understand new resources

https://bugs.eclipse.org/bugs/show_bug.cgi?id=486834

A resource that is new (such as in the New Model Wizard) cannot provide
a content-type via its persisted state because that doesn't yet exist,
so it is necessary to infer (as much as possible) a content-type from
the in-memory state.  This also introduces a cache by schema that can
help to avoid the cost of accessing persisted content redundantly for
the purpose of descibing the content.

5 files changed, 142 insertions, 4 deletions

diff --git a/plugins/infra/core/org.eclipse.papyrus.infra.core/src/org/eclipse/papyrus/infra/core/internal/language/DefaultLanguageProvider.java b/plugins/infra/core/org.eclipse.papyrus.infra.core/src/org/eclipse/papyrus/infra/core/internal/language/DefaultLanguageProvider.java
index 11f745b52d1..6f40db2c71b 100644
--- a/plugins/infra/core/org.eclipse.papyrus.infra.core/src/org/eclipse/papyrus/infra/core/internal/language/DefaultLanguageProvider.java
+++ b/plugins/infra/core/org.eclipse.papyrus.infra.core/src/org/eclipse/papyrus/infra/core/internal/language/DefaultLanguageProvider.java
@@ -15,10 +15,14 @@ package org.eclipse.papyrus.infra.core.internal.language;
 
 import java.io.File;
 import java.io.IOException;
+import java.io.StringReader;
+import java.util.Collection;
 import java.util.Collections;
+import java.util.HashSet;
 import java.util.List;
 import java.util.Map;
 import java.util.Set;
+import java.util.WeakHashMap;
 
 import org.eclipse.core.resources.IContainer;
 import org.eclipse.core.resources.IResource;
@@ -28,14 +32,20 @@ import org.eclipse.core.runtime.IConfigurationElement;
 import org.eclipse.core.runtime.IPath;
 import org.eclipse.core.runtime.Path;
 import org.eclipse.core.runtime.Platform;
+import org.eclipse.core.runtime.content.IContentDescription;
 import org.eclipse.core.runtime.content.IContentType;
 import org.eclipse.emf.common.util.URI;
+import org.eclipse.emf.ecore.EObject;
+import org.eclipse.emf.ecore.EPackage;
 import org.eclipse.emf.ecore.resource.ContentHandler;
+import org.eclipse.emf.ecore.resource.Resource;
 import org.eclipse.emf.ecore.resource.URIConverter;
+import org.eclipse.emf.ecore.xmi.XMIResource;
 import org.eclipse.papyrus.infra.core.Activator;
 import org.eclipse.papyrus.infra.core.language.ILanguage;
 import org.eclipse.papyrus.infra.core.language.ILanguageProvider;
 import org.eclipse.papyrus.infra.core.language.ILanguageService;
+import org.eclipse.papyrus.infra.core.resource.ModelSet;
 
 import com.google.common.collect.Lists;
 import com.google.common.collect.Sets;
@@ -44,6 +54,10 @@ import com.google.common.collect.Sets;
  * A default language provider for extensions that simply declare content-type matches for languages.
  */
 public class DefaultLanguageProvider implements ILanguageProvider {
+	private static Map<EPackage, IContentType> CONTENT_TYPES = new WeakHashMap<>();
+
+	private static IContentType NULL_CONTENT_TYPE = Platform.getContentTypeManager().getContentType("org.eclipse.emf.ecore.xmi"); //$NON-NLS-1$
+
 	private final Set<IContentType> contentTypes = Sets.newHashSet();
 
 	private final List<ILanguage> languages = Lists.newArrayList();
@@ -76,6 +90,17 @@ public class DefaultLanguageProvider implements ILanguageProvider {
 		}
 	}
 
+	@Override
+	public synchronized Iterable<ILanguage> getLanguages(ILanguageService languageService, ModelSet modelSet) {
+		if (!matchContentType(modelSet.getResources())) {
+			return Collections.emptyList();
+		} else {
+			// If any of my content-types matches, then all of my languages are present
+			resolveProxies();
+			return Collections.unmodifiableList(languages);
+		}
+	}
+
 	void addContentType(String id) {
 		IContentType contentType = Platform.getContentTypeManager().getContentType(id);
 		if (contentType == null) {
@@ -176,6 +201,73 @@ public class DefaultLanguageProvider implements ILanguageProvider {
 		return result;
 	}
 
+	private boolean matchContentType(Collection<? extends Resource> resources) {
+		boolean result = false;
+		Set<EPackage> packagesSeen = new HashSet<>();
+
+		out: for (Resource next : resources) {
+			String filename = next.getURI().lastSegment();
+
+			// TODO: Is it really sufficient to check only the roots? Other content could be contained
+			for (EObject root : next.getContents()) {
+				EPackage ePackage = root.eClass().getEPackage();
+				if (packagesSeen.add(ePackage)) {
+					IContentType contentType = getContentType(ePackage, filename);
+					if (contentType != null) {
+						for (IContentType type : contentTypes) {
+							if (contentType.isKindOf(type)) {
+								result = true;
+								break out;
+							}
+						}
+					}
+				}
+			}
+		}
+
+		return result;
+	}
+
+	/**
+	 * We don't actually have a mapping in EMF between packages and content-types,
+	 * so we infer it by feeding the platform's content-type system some fake inputs,
+	 * relaying on the standard EMF pattern of using XML namespace declarations to
+	 * determine content-type.
+	 * 
+	 * @param ePackage
+	 *            the package to infer the content-type
+	 * @param filename
+	 *            used as a hint to the platform's content-type manager
+	 * 
+	 * @return the content-type or a placeholder for unknown content (never {@code null})
+	 */
+	private IContentType getContentType(EPackage ePackage, String filename) {
+		return CONTENT_TYPES.computeIfAbsent(ePackage, package_ -> {
+			IContentType contentType = null;
+
+			StringReader xmiString = createStringReader(ePackage);
+			try {
+				IContentDescription desc = Platform.getContentTypeManager().getDescriptionFor(xmiString, filename, null);
+				contentType = (desc == null) ? null : desc.getContentType();
+			} catch (IOException e) {
+				// Not our content type, I guess
+			}
+
+			if (contentType == null) {
+				contentType = NULL_CONTENT_TYPE;
+			}
+
+			return contentType;
+		});
+	}
+
+	private StringReader createStringReader(EPackage ePackage) {
+		String xmi = String.format(
+				"<?xml version=\"1.0\" encoding=\"UTF-8\"?><xmi:XMI xmlns:xmi=\"%s\" xmlns:content=\"%s\"/>", //$NON-NLS-1$
+				XMIResource.XMI_2_1_URI, ePackage.getNsURI());
+		return new StringReader(xmi);
+	}
+
 	//
 	// Nested types
 	//
diff --git a/plugins/infra/core/org.eclipse.papyrus.infra.core/src/org/eclipse/papyrus/infra/core/internal/language/LanguageProviderRegistry.java b/plugins/infra/core/org.eclipse.papyrus.infra.core/src/org/eclipse/papyrus/infra/core/internal/language/LanguageProviderRegistry.java
index ce61df60eb6..db81831c5dc 100644
--- a/plugins/infra/core/org.eclipse.papyrus.infra.core/src/org/eclipse/papyrus/infra/core/internal/language/LanguageProviderRegistry.java
+++ b/plugins/infra/core/org.eclipse.papyrus.infra.core/src/org/eclipse/papyrus/infra/core/internal/language/LanguageProviderRegistry.java
@@ -30,6 +30,7 @@ import org.eclipse.papyrus.infra.core.language.ILanguageProvider;
 import org.eclipse.papyrus.infra.core.language.ILanguageService;
 import org.eclipse.papyrus.infra.core.language.Language;
 import org.eclipse.papyrus.infra.core.language.Version;
+import org.eclipse.papyrus.infra.core.resource.ModelSet;
 
 import com.google.common.base.Strings;
 import com.google.common.collect.Lists;
@@ -207,6 +208,11 @@ public class LanguageProviderRegistry implements ILanguageProvider.Registry {
 				return getInstance().getLanguages(languageService, modelURI, uriHasFileExtension);
 			}
 
+			@Override
+			public java.lang.Iterable<ILanguage> getLanguages(ILanguageService languageService, ModelSet modelSet) {
+				return getInstance().getLanguages(languageService, modelSet);
+			}
+
 			ILanguageProvider createDefaultProvider() throws CoreException {
 				DefaultLanguageProvider result = new DefaultLanguageProvider();
 
diff --git a/plugins/infra/core/org.eclipse.papyrus.infra.core/src/org/eclipse/papyrus/infra/core/internal/language/LanguageService.java b/plugins/infra/core/org.eclipse.papyrus.infra.core/src/org/eclipse/papyrus/infra/core/internal/language/LanguageService.java
index 0fca9314071..631995734d1 100644
--- a/plugins/infra/core/org.eclipse.papyrus.infra.core/src/org/eclipse/papyrus/infra/core/internal/language/LanguageService.java
+++ b/plugins/infra/core/org.eclipse.papyrus.infra.core/src/org/eclipse/papyrus/infra/core/internal/language/LanguageService.java
@@ -1,5 +1,5 @@
 /*****************************************************************************
- * Copyright (c) 2015 Christian W. Damus and others.
+ * Copyright (c) 2015, 2016 Christian W. Damus and others.
  * 
  * All rights reserved. This program and the accompanying materials
  * are made available under the terms of the Eclipse Public License v1.0
@@ -24,6 +24,7 @@ import org.eclipse.papyrus.infra.core.language.ILanguageChangeListener;
 import org.eclipse.papyrus.infra.core.language.ILanguageProvider;
 import org.eclipse.papyrus.infra.core.language.ILanguageService;
 import org.eclipse.papyrus.infra.core.language.LanguageChangeEvent;
+import org.eclipse.papyrus.infra.core.resource.ModelSet;
 import org.eclipse.papyrus.infra.core.services.IService;
 import org.eclipse.papyrus.infra.core.services.ServiceException;
 import org.eclipse.papyrus.infra.core.services.ServicesRegistry;
@@ -60,6 +61,17 @@ public class LanguageService extends PlatformObject implements ILanguageService,
 	}
 
 	@Override
+	public Set<ILanguage> getLanguages(ModelSet modelSet) {
+		Set<ILanguage> result = Sets.newHashSet();
+
+		for (ILanguageProvider next : languageProviders) {
+			Iterables.addAll(result, next.getLanguages(this, modelSet));
+		}
+
+		return result;
+	}
+
+	@Override
 	public void addLanguageChangeListener(ILanguageChangeListener listener) {
 		languageListeners.addIfAbsent(listener);
 	}
diff --git a/plugins/infra/core/org.eclipse.papyrus.infra.core/src/org/eclipse/papyrus/infra/core/language/ILanguageProvider.java b/plugins/infra/core/org.eclipse.papyrus.infra.core/src/org/eclipse/papyrus/infra/core/language/ILanguageProvider.java
index f1e2b3eacdd..76388ec7953 100644
--- a/plugins/infra/core/org.eclipse.papyrus.infra.core/src/org/eclipse/papyrus/infra/core/language/ILanguageProvider.java
+++ b/plugins/infra/core/org.eclipse.papyrus.infra.core/src/org/eclipse/papyrus/infra/core/language/ILanguageProvider.java
@@ -1,5 +1,5 @@
 /*****************************************************************************
- * Copyright (c) 2015 Christian W. Damus and others.
+ * Copyright (c) 2015, 2016 Christian W. Damus and others.
  * 
  * All rights reserved. This program and the accompanying materials
  * are made available under the terms of the Eclipse Public License v1.0
@@ -41,6 +41,21 @@ public interface ILanguageProvider {
 	 */
 	Iterable<ILanguage> getLanguages(ILanguageService languageService, URI modelURI, boolean uriHasFileExtension);
 
+	/**
+	 * Queries the languages that are instantiated in the specified model-set. This has the
+	 * advantage over the {@linkplain #getLanguages(ILanguageService, URI, boolean) URI-based API} of being able
+	 * to inspect resources that don't yet exist in the persistent store or are different from
+	 * the latest persisted state.
+	 * 
+	 * @param modelSet
+	 *            a {@link ModelSet} in which to find the instantiated languages
+	 * 
+	 * @return the languages instantiated in the specified resource
+	 */
+	default Iterable<ILanguage> getLanguages(ILanguageService languageService, ModelSet modelSet) {
+		return getLanguages(languageService, modelSet.getURIWithoutExtension(), false);
+	}
+
 	//
 	// Nested types
 	//
diff --git a/plugins/infra/core/org.eclipse.papyrus.infra.core/src/org/eclipse/papyrus/infra/core/language/ILanguageService.java b/plugins/infra/core/org.eclipse.papyrus.infra.core/src/org/eclipse/papyrus/infra/core/language/ILanguageService.java
index 7fa56614980..9ccc1effb22 100644
--- a/plugins/infra/core/org.eclipse.papyrus.infra.core/src/org/eclipse/papyrus/infra/core/language/ILanguageService.java
+++ b/plugins/infra/core/org.eclipse.papyrus.infra.core/src/org/eclipse/papyrus/infra/core/language/ILanguageService.java
@@ -1,5 +1,5 @@
 /*****************************************************************************
- * Copyright (c) 2015 Christian W. Damus and others.
+ * Copyright (c) 2015, 2016 Christian W. Damus and others.
  * 
  * All rights reserved. This program and the accompanying materials
  * are made available under the terms of the Eclipse Public License v1.0
@@ -55,6 +55,19 @@ public interface ILanguageService extends IAdaptable, ILanguageChangeListener {
 	Set<ILanguage> getLanguages(URI modelURI, boolean uriHasFileExtension);
 
 	/**
+	 * Queries the languages that are instantiated in the specified model-set. This has the
+	 * advantage over the {@linkplain #getLanguages(URI, boolean) URI-based API} of being able
+	 * to inspect resources that don't yet exist in the persistent store or are different from
+	 * the latest persisted state.
+	 * 
+	 * @param modelSet
+	 *            a {@link ModelSet} in which to find the instantiated languages
+	 * 
+	 * @return the languages instantiated in the specified resource
+	 */
+	Set<ILanguage> getLanguages(ModelSet modelSet);
+
+	/**
 	 * Adds a listener for language change notifications. Has no effect if the {@code listener} is already added.
 	 * 
 	 * @param listener
@@ -105,7 +118,7 @@ public interface ILanguageService extends IAdaptable, ILanguageChangeListener {
 			// No language service? No language models
 			result = Collections.emptyList();
 		} else {
-			result = service.getLanguages(modelSet.getURIWithoutExtension(), false).stream()
+			result = service.getLanguages(modelSet).stream()
 					.map(l -> l.getModel(modelSet))
 					.filter(Objects::nonNull)
 					.distinct() // Only unique models