Added JDT-derived import rewrite for snippets

headless-services/boot-java-language-server/src/main/java/org/springframework/ide/vscode/boot/java/handlers/BootJavaCompletionEngine.java

@@ -75,7 +75,7 @@ public class BootJavaCompletionEngine implements ICompletionEngine {
 			System.out.println("AST node found: " + node.getClass().getName());
 			Collection<ICompletionProposal> completions = new ArrayList<ICompletionProposal>();
 			completions.addAll(collectCompletionsForAnnotations(node, offset, document));
-			completions.addAll(snippets.getCompletions(document, offset, node));
+			completions.addAll(snippets.getCompletions(document, offset, node, cu));
 			return completions;
 		}
 

headless-services/boot-java-language-server/src/main/java/org/springframework/ide/vscode/boot/java/jdt/imports/ImportRewrite.java

@@ -0,0 +1,558 @@
+/*******************************************************************************
+ * Derived from:
+ * org.eclipse.jdt.core.dom.rewrite.ImportRewrite
+ * 
+ * for use in STS4, where IProject and ICompilationUnit are not available when parsing a Java source.
+ * 
+ * Original license:
+ *
+ * Copyright (c) 2000, 2016 IBM Corporation 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
+ *
+ * Contributors:
+ *     IBM Corporation - initial API and implementation
+ *     John Glassmyer <jogl@google.com> - import group sorting is broken - https://bugs.eclipse.org/430303
+ *     Lars Vogel <Lars.Vogel@vogella.com> - Contributions for
+ *     						Bug 473178
+ *******************************************************************************/
+package org.springframework.ide.vscode.boot.java.jdt.imports;
+
+import java.util.ArrayList;
+import java.util.Collections;
+import java.util.HashSet;
+import java.util.List;
+import java.util.Set;
+
+import org.eclipse.core.runtime.IProgressMonitor;
+import org.eclipse.jdt.core.ICompilationUnit;
+import org.eclipse.jdt.core.compiler.CharOperation;
+import org.eclipse.jdt.core.dom.ASTParser;
+import org.eclipse.jdt.core.dom.AbstractTypeDeclaration;
+import org.eclipse.jdt.core.dom.Comment;
+import org.eclipse.jdt.core.dom.CompilationUnit;
+import org.eclipse.jdt.core.dom.ImportDeclaration;
+import org.eclipse.jdt.core.dom.PackageDeclaration;
+import org.eclipse.jdt.core.dom.PrimitiveType;
+import org.eclipse.jdt.core.dom.SimpleName;
+import org.springframework.ide.vscode.commons.languageserver.completion.DocumentEdits;
+import org.springframework.ide.vscode.commons.util.text.IDocument;
+
+
+/**
+ * The {@link ImportRewrite} helps updating imports following a import order and on-demand imports threshold as configured by a project.
+ * <p>
+ * The import rewrite is created on a compilation unit and collects references to types that are added or removed. When adding imports, e.g. using
+ * {@link #addImport(String)}, the import rewrite evaluates if the type can be imported and returns the a reference to the type that can be used in code.
+ * This reference is either unqualified if the import could be added, or fully qualified if the import failed due to a conflict with another element of the same name.
+ * </p>
+ * <p>
+ * On {@link #rewriteImports(IProgressMonitor)} the rewrite translates these descriptions into
+ * text edits that can then be applied to the original source. The rewrite infrastructure tries to generate minimal text changes and only
+ * works on the import statements. It is possible to combine the result of an import rewrite with the result of a {@link org.eclipse.jdt.core.dom.rewrite.ASTRewrite}
+ * as long as no import statements are modified by the AST rewrite.
+ * </p>
+ * <p>The options controlling the import order and on-demand thresholds are:
+ * <ul><li>{@link #setImportOrder(String[])} specifies the import groups and their preferred order</li>
+ * <li>{@link #setOnDemandImportThreshold(int)} specifies the number of imports in a group needed for a on-demand import statement (star import)</li>
+ * <li>{@link #setStaticOnDemandImportThreshold(int)} specifies the number of static imports in a group needed for a on-demand import statement (star import)</li>
+ *</ul>
+ * This class is not intended to be subclassed.
+ * </p>
+ * @since 3.2
+ */
+@SuppressWarnings({ "rawtypes", "unchecked" })
+public final class ImportRewrite {
+
+	/**
+	 * A {@link ImportRewrite.ImportRewriteContext} can optionally be used in e.g. {@link ImportRewrite#addImport(String, ImportRewrite.ImportRewriteContext)} to
+	 * give more information about the types visible in the scope. These types can be for example inherited inner types where it is
+	 * unnecessary to add import statements for.
+	 *
+	 * </p>
+	 * <p>
+	 * This class can be implemented by clients.
+	 * </p>
+	 */
+	public static abstract class ImportRewriteContext {
+
+		/**
+		 * Result constant signaling that the given element is know in the context.
+		 */
+		public final static int RES_NAME_FOUND= 1;
+
+		/**
+		 * Result constant signaling that the given element is not know in the context.
+		 */
+		public final static int RES_NAME_UNKNOWN= 2;
+
+		/**
+		 * Result constant signaling that the given element is conflicting with an other element in the context.
+		 */
+		public final static int RES_NAME_CONFLICT= 3;
+
+		/**
+		 * Result constant signaling that the given element must be imported explicitly (and must not be folded into
+		 * an on-demand import or filtered as an implicit import).
+		 *
+		 * @since 3.11
+		 */
+		public final static int RES_NAME_UNKNOWN_NEEDS_EXPLICIT_IMPORT= 4;
+
+		/**
+		 * Kind constant specifying that the element is a type import.
+		 */
+		public final static int KIND_TYPE= 1;
+
+		/**
+		 * Kind constant specifying that the element is a static field import.
+		 */
+		public final static int KIND_STATIC_FIELD= 2;
+
+		/**
+		 * Kind constant specifying that the element is a static method import.
+		 */
+		public final static int KIND_STATIC_METHOD= 3;
+
+		/**
+		 * Searches for the given element in the context and reports if the element is known ({@link #RES_NAME_FOUND}),
+		 * unknown ({@link #RES_NAME_UNKNOWN}), unknown in the context but known to require an explicit import
+		 * ({@link #RES_NAME_UNKNOWN_NEEDS_EXPLICIT_IMPORT}), or if its name conflicts ({@link #RES_NAME_CONFLICT})
+		 * with an other element.
+		 *
+		 * @param qualifier The qualifier of the element, can be package or the qualified name of a type
+		 * @param name The simple name of the element; either a type, method or field name or * for on-demand imports.
+		 * @param kind The kind of the element. Can be either {@link #KIND_TYPE}, {@link #KIND_STATIC_FIELD} or
+		 * {@link #KIND_STATIC_METHOD}. Implementors should be prepared for new, currently unspecified kinds and return
+		 * {@link #RES_NAME_UNKNOWN} by default.
+		 * @return Returns the result of the lookup. Can be either {@link #RES_NAME_FOUND}, {@link #RES_NAME_UNKNOWN},
+		 * {@link #RES_NAME_CONFLICT}, or {@link #RES_NAME_UNKNOWN_NEEDS_EXPLICIT_IMPORT}.
+		 */
+		public abstract int findInContext(String qualifier, String name, int kind);
+	}
+
+	private static final char STATIC_PREFIX= 's';
+	private static final char NORMAL_PREFIX= 'n';
+
+	private final ImportRewriteContext defaultContext;
+
+	private final CompilationUnit astRoot;
+
+	private final boolean restoreExistingImports;
+	private final List existingImports;
+
+
+	private List<String> addedImports;
+
+	/**
+	 * Simple names of non-static imports which must not be reduced into on-demand imports
+	 * or filtered out as implicit.
+	 */
+	private Set<String> typeExplicitSimpleNames;
+
+
+	private boolean filterImplicitImports;
+	private boolean useContextToFilterImplicitImports;
+
+
+	/**
+	 * Creates an {@link ImportRewrite} from an AST ({@link CompilationUnit}). The AST has to be created from an
+	 * {@link ICompilationUnit}, that means {@link ASTParser#setSource(ICompilationUnit)} has been used when creating the
+	 * AST. If <code>restoreExistingImports</code> is <code>true</code>, all existing imports are kept, and new imports
+	 * will be inserted at best matching locations. If <code>restoreExistingImports</code> is <code>false</code>, the
+	 * existing imports will be removed and only the newly added imports will be created.
+	 * <p>
+	 * Note that this method is more efficient than using {@link #create(ICompilationUnit, boolean)} if an AST is already available.
+	 * </p>
+	 * @param astRoot the AST root node to create the imports for
+	 * @param restoreExistingImports specifies if the existing imports should be kept or removed.
+	 * @return the created import rewriter.
+	 * @throws IllegalArgumentException thrown when the passed AST is null or was not created from a compilation unit.
+	 */
+	public static ImportRewrite create(CompilationUnit astRoot, boolean restoreExistingImports) {
+		if (astRoot == null) {
+			throw new IllegalArgumentException("AST must not be null"); //$NON-NLS-1$
+		}
+
+		List existingImport= null;
+		if (restoreExistingImports) {
+			existingImport= new ArrayList();
+			List imports= astRoot.imports();
+			for (int i= 0; i < imports.size(); i++) {
+				ImportDeclaration curr= (ImportDeclaration) imports.get(i);
+				StringBuffer buf= new StringBuffer();
+				buf.append(curr.isStatic() ? STATIC_PREFIX : NORMAL_PREFIX).append(curr.getName().getFullyQualifiedName());
+				if (curr.isOnDemand()) {
+					if (buf.length() > 1)
+						buf.append('.');
+					buf.append('*');
+				}
+				existingImport.add(buf.toString());
+			}
+		}
+		return new ImportRewrite(astRoot, existingImport);
+	}
+
+	private ImportRewrite(CompilationUnit astRoot, List existingImports) {
+		this.astRoot= astRoot; // might be null
+		if (existingImports != null) {
+			this.existingImports= existingImports;
+			this.restoreExistingImports= !existingImports.isEmpty();
+		} else {
+			this.existingImports= new ArrayList();
+			this.restoreExistingImports= false;
+		}
+		this.filterImplicitImports= true;
+		// consider that no contexts are used
+		this.useContextToFilterImplicitImports = false;
+
+		this.defaultContext= new ImportRewriteContext() {
+			@Override
+			public int findInContext(String qualifier, String name, int kind) {
+				return findInImports(qualifier, name, kind);
+			}
+		};
+		this.addedImports= new ArrayList<>();
+		this.typeExplicitSimpleNames = new HashSet<>();
+	}
+
+	/**
+	 * Returns the default rewrite context that only knows about the imported types. Clients
+	 * can write their own context and use the default context for the default behavior.
+	 * @return the default import rewrite context.
+	 */
+	public ImportRewriteContext getDefaultImportRewriteContext() {
+		return this.defaultContext;
+	}
+
+	/**
+	 * Specifies that implicit imports (for types in <code>java.lang</code>, types in the same package as the rewrite
+	 * compilation unit, and types in the compilation unit's main type) should not be created, except if necessary to
+	 * resolve an on-demand import conflict.
+	 * <p>
+	 * The filter is enabled by default.
+	 * </p>
+	 * <p>
+	 * Note: {@link #setUseContextToFilterImplicitImports(boolean)} can be used to filter implicit imports
+	 * when a context is used.
+	 * </p>
+	 *
+	 * @param filterImplicitImports
+	 *            if <code>true</code>, implicit imports will be filtered
+	 *
+	 * @see #setUseContextToFilterImplicitImports(boolean)
+	 */
+	public void setFilterImplicitImports(boolean filterImplicitImports) {
+		this.filterImplicitImports= filterImplicitImports;
+	}
+
+	/**
+	* Sets whether a context should be used to properly filter implicit imports.
+	* <p>
+	* By default, the option is disabled to preserve pre-3.6 behavior.
+	* </p>
+	* <p>
+	* When this option is set, the context passed to the <code>addImport*(...)</code> methods is used to determine
+	* whether an import can be filtered because the type is implicitly visible. Note that too many imports
+	* may be kept if this option is set and <code>addImport*(...)</code> methods are called without a context.
+	* </p>
+	*
+	* @param useContextToFilterImplicitImports the given setting
+	*
+	* @see #setFilterImplicitImports(boolean)
+	* @since 3.6
+	*/
+	public void setUseContextToFilterImplicitImports(boolean useContextToFilterImplicitImports) {
+		this.useContextToFilterImplicitImports = useContextToFilterImplicitImports;
+	}
+
+	private static int compareImport(char prefix, String qualifier, String name, String curr) {
+		if (curr.charAt(0) != prefix || !curr.endsWith(name)) {
+			return ImportRewriteContext.RES_NAME_UNKNOWN;
+		}
+
+		curr= curr.substring(1); // remove the prefix
+
+		if (curr.length() == name.length()) {
+			if (qualifier.length() == 0) {
+				return ImportRewriteContext.RES_NAME_FOUND;
+			}
+			return ImportRewriteContext.RES_NAME_CONFLICT;
+		}
+		// at this place: curr.length > name.length
+
+		int dotPos= curr.length() - name.length() - 1;
+		if (curr.charAt(dotPos) != '.') {
+			return ImportRewriteContext.RES_NAME_UNKNOWN;
+		}
+		if (qualifier.length() != dotPos || !curr.startsWith(qualifier)) {
+			return ImportRewriteContext.RES_NAME_CONFLICT;
+		}
+		return ImportRewriteContext.RES_NAME_FOUND;
+	}
+
+	/**
+	 * Not API, package visibility as accessed from an anonymous type
+	 */
+	/* package */ final int findInImports(String qualifier, String name, int kind) {
+		boolean allowAmbiguity=  (kind == ImportRewriteContext.KIND_STATIC_METHOD) || (name.length() == 1 && name.charAt(0) == '*');
+		List imports= this.existingImports;
+		char prefix= (kind == ImportRewriteContext.KIND_TYPE) ? NORMAL_PREFIX : STATIC_PREFIX;
+
+		for (int i= imports.size() - 1; i >= 0 ; i--) {
+			String curr= (String) imports.get(i);
+			int res= compareImport(prefix, qualifier, name, curr);
+			if (res != ImportRewriteContext.RES_NAME_UNKNOWN) {
+				if (!allowAmbiguity || res == ImportRewriteContext.RES_NAME_FOUND) {
+					if (prefix != STATIC_PREFIX) {
+						return res;
+					}
+				}
+			}
+		}
+
+		String packageName = getPackageName();
+		if (kind == ImportRewriteContext.KIND_TYPE) {
+			if (this.filterImplicitImports && this.useContextToFilterImplicitImports) {
+
+				// [STS4] No ICompilationUnit available as there is no class file or associated IJavaElement available for the source
+
+//				String mainTypeSimpleName= JavaCore.removeJavaLikeExtension(this.compilationUnit.getElementName());
+//				String mainTypeName= Util.concatenateName(packageName, mainTypeSimpleName, '.');
+//				if (qualifier.equals(packageName)
+//						|| mainTypeName.equals(Util.concatenateName(qualifier, name, '.'))) {
+//					return ImportRewriteContext.RES_NAME_FOUND;
+//				}
+
+				if (this.astRoot != null) {
+					List<AbstractTypeDeclaration> types = this.astRoot.types();
+					int nTypes = types.size();
+					for (int i = 0; i < nTypes; i++) {
+						AbstractTypeDeclaration type = types.get(i);
+						SimpleName simpleName = type.getName();
+						if (simpleName.getIdentifier().equals(name)) {
+							return qualifier.equals(packageName)
+									? ImportRewriteContext.RES_NAME_FOUND
+									: ImportRewriteContext.RES_NAME_CONFLICT;
+						}
+					}
+				} else {
+
+					// [STS4] No ICompilationUnit available as there is no class file or associated IJavaElement available for the source
+//					try {
+//						IType[] types = this.compilationUnit.getTypes();
+//						int nTypes = types.length;
+//						for (int i = 0; i < nTypes; i++) {
+//							IType type = types[i];
+//							String typeName = type.getElementName();
+//							if (typeName.equals(name)) {
+//								return qualifier.equals(packageName)
+//										? ImportRewriteContext.RES_NAME_FOUND
+//										: ImportRewriteContext.RES_NAME_CONFLICT;
+//							}
+//						}
+//					} catch (JavaModelException e) {
+//						// don't want to throw an exception here
+//					}
+				}
+			}
+		}
+
+		return ImportRewriteContext.RES_NAME_UNKNOWN;
+	}
+
+	private String getPackageName() {
+		// [STS4] No ICompilationUnit available as there is no class file or associated IJavaElement available for the source
+//		this.compilationUnit.getParent().getElementName();
+		return this.astRoot.getPackage().getName().getFullyQualifiedName();
+	}
+
+	/**
+	 * Adds a new import to the rewriter's record and returns a type reference that can be used
+	 * in the code. The type binding can only be an array or non-generic type.
+	 * 	<p>
+ 	 * No imports are added for types that are already known. If a import for a type is recorded to be removed, this record is discarded instead.
+	 * </p>
+	 * <p>
+	 * The content of the compilation unit itself is actually not modified
+	 * in any way by this method; rather, the rewriter just records that a new import has been added.
+	 * </p>
+	 * @param qualifiedTypeName the qualified type name of the type to be added
+	 * @param context an optional context that knows about types visible in the current scope or <code>null</code>
+	 * to use the default context only using the available imports.
+	 * @return a type reference for the given qualified type name. The type name is a simple name if an import could be used,
+	 * or else a qualified name if an import conflict prevented an import.
+	 */
+	public String addImport(String qualifiedTypeName, ImportRewriteContext context) {
+		int angleBracketOffset= qualifiedTypeName.indexOf('<');
+		if (angleBracketOffset != -1) {
+			return internalAddImport(qualifiedTypeName.substring(0, angleBracketOffset), context) + qualifiedTypeName.substring(angleBracketOffset);
+		}
+		int bracketOffset= qualifiedTypeName.indexOf('[');
+		if (bracketOffset != -1) {
+			return internalAddImport(qualifiedTypeName.substring(0, bracketOffset), context) + qualifiedTypeName.substring(bracketOffset);
+		}
+		return internalAddImport(qualifiedTypeName, context);
+	}
+
+	/**
+	 * Adds a new import to the rewriter's record and returns a type reference that can be used
+	 * in the code. The type binding can only be an array or non-generic type.
+	 * 	<p>
+ 	 * No imports are added for types that are already known. If a import for a type is recorded to be removed, this record is discarded instead.
+	 * </p>
+	 * <p>
+	 * The content of the compilation unit itself is actually not modified
+	 * in any way by this method; rather, the rewriter just records that a new import has been added.
+	 * </p>
+	 * @param qualifiedTypeName the qualified type name of the type to be added
+	 * @return a type reference for the given qualified type name. The type name is a simple name if an import could be used,
+	 * or else a qualified name if an import conflict prevented an import.
+	 */
+	public String addImport(String qualifiedTypeName) {
+		return addImport(qualifiedTypeName, this.defaultContext);
+	}
+
+
+
+	private String internalAddImport(String fullTypeName, ImportRewriteContext context) {
+		int idx= fullTypeName.lastIndexOf('.');
+		String typeContainerName, typeName;
+		if (idx != -1) {
+			typeContainerName= fullTypeName.substring(0, idx);
+			typeName= fullTypeName.substring(idx + 1);
+		} else {
+			typeContainerName= ""; //$NON-NLS-1$
+			typeName= fullTypeName;
+		}
+
+		if (typeContainerName.length() == 0 && PrimitiveType.toCode(typeName) != null) {
+			return fullTypeName;
+		}
+
+		if (context == null)
+			context= this.defaultContext;
+
+		int res= context.findInContext(typeContainerName, typeName, ImportRewriteContext.KIND_TYPE);
+		if (res == ImportRewriteContext.RES_NAME_CONFLICT) {
+			return fullTypeName;
+		}
+		if (res == ImportRewriteContext.RES_NAME_UNKNOWN) {
+			addEntry(NORMAL_PREFIX + fullTypeName);
+		}
+		if (res == ImportRewriteContext.RES_NAME_UNKNOWN_NEEDS_EXPLICIT_IMPORT) {
+			addEntry(NORMAL_PREFIX + fullTypeName);
+			this.typeExplicitSimpleNames.add(typeName);
+		}
+		return typeName;
+	}
+
+	private void addEntry(String entry) {
+		this.existingImports.add(entry);
+
+		this.addedImports.add(entry);
+	}
+
+
+
+	/**
+	 * Returns all non-static imports that are recorded to be added.
+	 *
+	 * @return the imports recorded to be added.
+	 */
+	public String[] getAddedImports() {
+		return filterFromList(this.addedImports, NORMAL_PREFIX);
+	}
+
+	/**
+	 * Returns <code>true</code> if imports have been recorded to be added or removed.
+	 * @return boolean returns if any changes to imports have been recorded.
+	 */
+	public boolean hasRecordedChanges() {
+		return !this.restoreExistingImports
+				|| !this.addedImports.isEmpty();
+	}
+
+	private static String[] filterFromList(List<String> imports, char prefix) {
+		if (imports == null) {
+			return CharOperation.NO_STRINGS;
+		}
+		List<String> res= new ArrayList<>();
+		for (String curr : imports) {
+			if (prefix == curr.charAt(0)) {
+				res.add(curr.substring(1));
+			}
+		}
+		return res.toArray(new String[res.size()]);
+	}
+
+
+	/**
+	 * Reads the positions of each existing import declaration along with any associated comments,
+	 * and returns these in a list whose iteration order reflects the existing order of the imports
+	 * in the compilation unit.
+	 */
+	private int getAddedImportsInsertLocation() {
+		List<ImportDeclaration> importDeclarations = astRoot.imports();
+
+		if (importDeclarations == null) {
+			importDeclarations = Collections.emptyList();
+		}
+
+		List<Comment> comments = astRoot.getCommentList();
+
+		int currentCommentIndex = 0;
+
+		// Skip over package and file header comments (see https://bugs.eclipse.org/121428).
+		ImportDeclaration firstImport = importDeclarations.get(0);
+		PackageDeclaration packageDeclaration = astRoot.getPackage();
+		int firstImportStartPosition = packageDeclaration == null
+				? firstImport.getStartPosition()
+				: astRoot.getExtendedStartPosition(packageDeclaration)
+						+ astRoot.getExtendedLength(packageDeclaration);
+		while (currentCommentIndex < comments.size()
+				&& comments.get(currentCommentIndex).getStartPosition() < firstImportStartPosition) {
+			currentCommentIndex++;
+		}
+
+		int previousExtendedEndPosition = -1;
+		for (ImportDeclaration currentImport : importDeclarations) {
+			int extendedEndPosition = astRoot.getExtendedStartPosition(currentImport)
+					+ astRoot.getExtendedLength(currentImport);
+
+			int commentAfterImportIndex = currentCommentIndex;
+			while (commentAfterImportIndex < comments.size()
+					&& comments.get(commentAfterImportIndex).getStartPosition() < extendedEndPosition) {
+				commentAfterImportIndex++;
+			}
+
+
+			currentCommentIndex = commentAfterImportIndex;
+			previousExtendedEndPosition = extendedEndPosition;
+		}
+
+		return previousExtendedEndPosition;
+	}
+
+	public DocumentEdits createEdit(IDocument doc) {
+		DocumentEdits edits = null;
+		StringBuffer buffer = new StringBuffer();
+
+		String[] createdImprts = getAddedImports();
+		if (createdImprts != null && createdImprts.length >0) {
+			edits =new DocumentEdits(doc);
+			buffer.append('\n');
+			for (String imp : createdImprts) {
+				buffer.append("import ");
+				buffer.append(imp);
+				buffer.append(';');
+				buffer.append('\n');
+			}
+			edits.insert(getAddedImportsInsertLocation(), buffer.toString());
+
+		}
+		return edits;
+	}
+}

headless-services/boot-java-language-server/src/main/java/org/springframework/ide/vscode/boot/java/snippets/JavaSnippet.java

@@ -14,6 +14,7 @@ import java.util.List;
 import java.util.Optional;
 
 import org.eclipse.jdt.core.dom.ASTNode;
+import org.eclipse.jdt.core.dom.CompilationUnit;
 import org.eclipse.lsp4j.CompletionItemKind;
 import org.springframework.ide.vscode.commons.languageserver.completion.ICompletionProposal;
 import org.springframework.ide.vscode.commons.languageserver.util.DocumentRegion;
@@ -44,12 +45,13 @@ public class JavaSnippet {
 	}
 
 	public Optional<ICompletionProposal> generateCompletion(Supplier<SnippetBuilder> snippetBuilderFactory,
-			DocumentRegion query, ASTNode node) {
+			DocumentRegion query, ASTNode node, CompilationUnit cu) {
 
 		if (context.appliesTo(node)) {
 			return Optional.of(
 					new JavaSnippetCompletion(snippetBuilderFactory,
 							query,
+							cu,
 							this
 					)
 			);
@@ -66,8 +68,8 @@ public class JavaSnippet {
 		return this.template;
 	}
 
-	public  List<String> getImports() {
-		return this.imports;
+	public  Optional<List<String>> getImports() {
+		return Optional.of(this.imports);
 	}
 
 	public CompletionItemKind getKind() {

headless-services/boot-java-language-server/src/main/java/org/springframework/ide/vscode/boot/java/snippets/JavaSnippetCompletion.java

@@ -12,7 +12,9 @@ package org.springframework.ide.vscode.boot.java.snippets;
 
 import java.util.Optional;
 
+import org.eclipse.jdt.core.dom.CompilationUnit;
 import org.eclipse.lsp4j.CompletionItemKind;
+import org.springframework.ide.vscode.boot.java.jdt.imports.ImportRewrite;
 import org.springframework.ide.vscode.commons.languageserver.completion.DocumentEdits;
 import org.springframework.ide.vscode.commons.languageserver.completion.ICompletionProposal;
 import org.springframework.ide.vscode.commons.languageserver.util.DocumentRegion;
@@ -27,10 +29,12 @@ public class JavaSnippetCompletion implements ICompletionProposal{
 	private DocumentRegion query;
 	private JavaSnippet javaSnippet;
 	private Supplier<SnippetBuilder> snippetBuilderFactory;
+	private CompilationUnit cu;
 
-	public JavaSnippetCompletion(Supplier<SnippetBuilder> snippetBuilderFactory, DocumentRegion query, JavaSnippet javaSnippet) {
+	public JavaSnippetCompletion(Supplier<SnippetBuilder> snippetBuilderFactory, DocumentRegion query, CompilationUnit cu, JavaSnippet javaSnippet) {
 		this.snippetBuilderFactory = snippetBuilderFactory;
 		this.query = query;
+		this.cu = cu;
 		this.javaSnippet = javaSnippet;
 	}
 
@@ -61,8 +65,17 @@ public class JavaSnippetCompletion implements ICompletionProposal{
 
 	@Override
 	public Optional<DocumentEdits> getAdditionalEdit() {
-		DocumentEdits edit = new DocumentEdits(query.getDocument());
-		edit.insert(0, "import my.stuff;\n");
-		return Optional.of(edit );
+		ImportRewrite rewrite =  ImportRewrite.create(cu, true);
+
+		javaSnippet.getImports().ifPresent((imprts ->
+		{
+			for (String imprt : imprts) {
+				rewrite.addImport(imprt);
+			}
+		}));
+
+		DocumentEdits edit = rewrite.createEdit(query.getDocument());
+
+		return Optional.of(edit);
 	}
 }

headless-services/boot-java-language-server/src/main/java/org/springframework/ide/vscode/boot/java/snippets/JavaSnippetManager.java

@@ -15,6 +15,7 @@ import java.util.Collection;
 import java.util.List;
 
 import org.eclipse.jdt.core.dom.ASTNode;
+import org.eclipse.jdt.core.dom.CompilationUnit;
 import org.springframework.ide.vscode.commons.languageserver.completion.ICompletionProposal;
 import org.springframework.ide.vscode.commons.languageserver.util.DocumentRegion;
 import org.springframework.ide.vscode.commons.languageserver.util.PrefixFinder;
@@ -46,14 +47,14 @@ public class JavaSnippetManager {
 
 	}
 
-	public Collection<ICompletionProposal> getCompletions(IDocument doc, int offset, ASTNode node) {
+	public Collection<ICompletionProposal> getCompletions(IDocument doc, int offset, ASTNode node, CompilationUnit cu) {
 		Collection<ICompletionProposal> completions = new ArrayList<>();
 
 		DocumentRegion query = PREFIX_FINDER.getPrefixRegion(doc, offset);
 
 		for (JavaSnippet javaSnippet : snippets) {
 			if (FuzzyMatcher.matchScore(query.toString(), javaSnippet.getName()) != 0) {
-				javaSnippet.generateCompletion(snippetBuilderFactory, query, node)
+				javaSnippet.generateCompletion(snippetBuilderFactory, query, node, cu)
 						.ifPresent((completion) -> completions.add(completion));
 			}
 		}