Manage snippet registry to write snippet in JSON

Fixes eclipse-lemminx#640

Signed-off-by: azerr <azerr@redhat.com>

org.eclipse.lemminx/src/main/java/org/eclipse/lemminx/commons/snippets/ISnippetContext.java

@@ -0,0 +1,33 @@
+/*******************************************************************************
+* Copyright (c) 2020 Red Hat Inc. and others.
+* All rights reserved. This program and the accompanying materials
+* which accompanies this distribution, and is available at
+* http://www.eclipse.org/legal/epl-v20.html
+*
+* SPDX-License-Identifier: EPL-2.0
+* 
+* Contributors:
+*     Red Hat Inc. - initial API and implementation
+*******************************************************************************/
+package org.eclipse.lemminx.commons.snippets;
+
+import java.util.Map;
+
+/**
+ * Snippet context used to filter the snippet.
+ * 
+ * @author Angelo ZERR
+ *
+ * @param <T> the value type waited by the snippet context.
+ */
+public interface ISnippetContext<T> {
+
+	/**
+	 * Return true if the given value match the snippet context and false otherwise.
+	 * 
+	 * @param value the value to check.
+	 * @return true if the given value match the snippet context and false
+	 *         otherwise.
+	 */
+	boolean isMatch(T value, Map<String, String> model);
+}

org.eclipse.lemminx/src/main/java/org/eclipse/lemminx/commons/snippets/ISnippetRegistryLoader.java

@@ -0,0 +1,38 @@
+/*******************************************************************************
+* Copyright (c) 2020 Red Hat Inc. and others.
+* All rights reserved. This program and the accompanying materials
+* which accompanies this distribution, and is available at
+* http://www.eclipse.org/legal/epl-v20.html
+*
+* SPDX-License-Identifier: EPL-2.0
+* 
+* Contributors:
+*     Red Hat Inc. - initial API and implementation
+*******************************************************************************/
+package org.eclipse.lemminx.commons.snippets;
+
+/**
+ * Loader used to load snippets in a given registry for a language id.
+ * 
+ * @author Angelo ZERR
+ *
+ */
+public interface ISnippetRegistryLoader {
+
+	/**
+	 * Register snippets in the given snippet registry.
+	 * 
+	 * @param registry
+	 * @throws Exception
+	 */
+	void load(SnippetRegistry registry) throws Exception;
+
+	/**
+	 * Returns the language id and null otherwise.
+	 * 
+	 * @return the language id and null otherwise.
+	 */
+	default String getLanguageId() {
+		return null;
+	}
+}

org.eclipse.lemminx/src/main/java/org/eclipse/lemminx/commons/snippets/Snippet.java

@@ -0,0 +1,88 @@
+/*******************************************************************************
+* Copyright (c) 2020 Red Hat Inc. and others.
+* All rights reserved. This program and the accompanying materials
+* which accompanies this distribution, and is available at
+* http://www.eclipse.org/legal/epl-v20.html
+*
+* SPDX-License-Identifier: EPL-2.0
+* 
+* Contributors:
+*     Red Hat Inc. - initial API and implementation
+*******************************************************************************/
+package org.eclipse.lemminx.commons.snippets;
+
+import java.util.List;
+import java.util.Map;
+import java.util.function.BiPredicate;
+
+/**
+ * Snippet description (like vscode snippet).
+ * 
+ * @author Angelo ZERR
+ *
+ */
+public class Snippet {
+
+	private List<String> prefixes;
+
+	private List<String> body;
+
+	private String description;
+
+	private String scope;
+
+	private ISnippetContext<?> context;
+
+	public List<String> getPrefixes() {
+		return prefixes;
+	}
+
+	public void setPrefixes(List<String> prefixes) {
+		this.prefixes = prefixes;
+	}
+
+	public List<String> getBody() {
+		return body;
+	}
+
+	public void setBody(List<String> body) {
+		this.body = body;
+	}
+
+	public String getDescription() {
+		return description;
+	}
+
+	public void setDescription(String description) {
+		this.description = description;
+	}
+
+	public String getScope() {
+		return scope;
+	}
+
+	public void setScope(String scope) {
+		this.scope = scope;
+	}
+
+	public ISnippetContext<?> getContext() {
+		return context;
+	}
+
+	public void setContext(ISnippetContext<?> context) {
+		this.context = context;
+	}
+
+	public boolean hasContext() {
+		return getContext() != null;
+	}
+
+	public boolean match(BiPredicate<ISnippetContext<?>, Map<String, String>> contextFilter,
+			Map<String, String> model) {
+		if (!hasContext()) {
+			return true;
+		}
+		return contextFilter.test(getContext(), model);
+	}
+
+}

org.eclipse.lemminx/src/main/java/org/eclipse/lemminx/commons/snippets/SnippetDeserializer.java

@@ -0,0 +1,108 @@
+/*******************************************************************************
+* Copyright (c) 2020 Red Hat Inc. and others.
+* All rights reserved. This program and the accompanying materials
+* which accompanies this distribution, and is available at
+* http://www.eclipse.org/legal/epl-v20.html
+*
+* SPDX-License-Identifier: EPL-2.0
+* 
+* Contributors:
+*     Red Hat Inc. - initial API and implementation
+*******************************************************************************/
+package org.eclipse.lemminx.commons.snippets;
+
+import java.lang.reflect.Type;
+import java.util.ArrayList;
+import java.util.List;
+
+import com.google.gson.JsonArray;
+import com.google.gson.JsonDeserializationContext;
+import com.google.gson.JsonDeserializer;
+import com.google.gson.JsonElement;
+import com.google.gson.JsonObject;
+import com.google.gson.JsonParseException;
+import com.google.gson.TypeAdapter;
+
+/**
+ * GSON deserializer to build Snippet from vscode JSON snippet.
+ * 
+ * @author Angelo ZERR
+ *
+ */
+class SnippetDeserializer implements JsonDeserializer<Snippet> {
+
+	private static final String PREFIX_ELT = "prefix";
+	private static final String DESCRIPTION_ELT = "description";
+	private static final String SCOPE_ELT = "scope";
+	private static final String BODY_ELT = "body";
+	private static final String CONTEXT_ELT = "context";
+
+	private final TypeAdapter<? extends ISnippetContext<?>> contextDeserializer;
+
+	public SnippetDeserializer(TypeAdapter<? extends ISnippetContext<?>> contextDeserializer) {
+		this.contextDeserializer = contextDeserializer;
+	}
+
+	@Override
+	public Snippet deserialize(JsonElement json, Type typeOfT, JsonDeserializationContext context)
+			throws JsonParseException {
+		Snippet snippet = new Snippet();
+		JsonObject snippetObj = json.getAsJsonObject();
+
+		// prefix
+		List<String> prefixes = new ArrayList<>();
+		JsonElement prefixElt = snippetObj.get(PREFIX_ELT);
+		if (prefixElt != null) {
+			if (prefixElt.isJsonArray()) {
+				JsonArray prefixArray = (JsonArray) prefixElt;
+				prefixArray.forEach(elt -> {
+					prefixes.add(elt.getAsString());
+				});
+			} else if (prefixElt.isJsonPrimitive()) {
+				prefixes.add(prefixElt.getAsString());
+			}
+		}
+		snippet.setPrefixes(prefixes);
+
+		// body
+		List<String> body = new ArrayList<>();
+		JsonElement bodyElt = snippetObj.get(BODY_ELT);
+		if (bodyElt != null) {
+			if (bodyElt.isJsonArray()) {
+				JsonArray bodyArray = (JsonArray) bodyElt;
+				bodyArray.forEach(elt -> {
+					body.add(elt.getAsString());
+				});
+			} else if (bodyElt.isJsonPrimitive()) {
+				body.add(bodyElt.getAsString());
+			}
+		}
+		snippet.setBody(body);
+
+		// description
+		JsonElement descriptionElt = snippetObj.get(DESCRIPTION_ELT);
+		if (descriptionElt != null) {
+			String description = descriptionElt.getAsString();
+			snippet.setDescription(description);
+		}
+
+		// scope
+		JsonElement scopeElt = snippetObj.get(SCOPE_ELT);
+		if (scopeElt != null) {
+			String scope = scopeElt.getAsString();
+			snippet.setScope(scope);
+		}
+
+		// context
+		if (contextDeserializer != null) {
+			JsonElement contextElt = snippetObj.get(CONTEXT_ELT);
+			if (contextElt != null) {
+				ISnippetContext<?> snippetContext = contextDeserializer.fromJsonTree(contextElt);
+				snippet.setContext(snippetContext);
+			}
+		}
+
+		return snippet;
+	}
+
+}