Add a convenience AstTransformation base class for BOMs

Plugin authors can extend this class, provide missing methods,
and specify a BOM to add to the dependency management lookup
(i.e. dependencies by artifactId)

spring-boot-cli/src/main/java/org/springframework/boot/cli/compiler/GenericBomAstTransformation.java

@@ -0,0 +1,141 @@
+/*
+ * Copyright 2014-2015 the original author or authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.springframework.boot.cli.compiler;
+
+import java.util.ArrayList;
+import java.util.Arrays;
+import java.util.Collections;
+import java.util.List;
+
+import org.codehaus.groovy.ast.ASTNode;
+import org.codehaus.groovy.ast.AnnotatedNode;
+import org.codehaus.groovy.ast.AnnotationNode;
+import org.codehaus.groovy.ast.ClassHelper;
+import org.codehaus.groovy.ast.ClassNode;
+import org.codehaus.groovy.ast.ModuleNode;
+import org.codehaus.groovy.ast.PackageNode;
+import org.codehaus.groovy.ast.expr.ConstantExpression;
+import org.codehaus.groovy.ast.expr.Expression;
+import org.codehaus.groovy.ast.expr.ListExpression;
+import org.codehaus.groovy.control.CompilePhase;
+import org.codehaus.groovy.control.SourceUnit;
+import org.codehaus.groovy.transform.GroovyASTTransformation;
+import org.springframework.boot.groovy.DependencyManagementBom;
+import org.springframework.core.Ordered;
+
+/**
+ * A base class that lets plugin authors easily add additional BOMs to all apps. All the
+ * dependencies in the bom (and it's transitives) will be added to the dependency
+ * management lookup, so an app can use just the artifact id (e.g. "spring-jdbc") in a
+ * <code>@Grab</code>. To install, implement the missing methods and list the class in
+ * <code>META-INF/services/org.springframework.boot.cli.compiler.SpringBootAstTransformation</code>
+ * . The {@link #getOrder()} value needs to be before
+ * {@link DependencyManagementBomTransformation#ORDER}.
+ *
+ * @author Dave Syer
+ *
+ */
+@GroovyASTTransformation(phase = CompilePhase.CONVERSION)
+public abstract class GenericBomAstTransformation
+		implements SpringBootAstTransformation, Ordered {
+
+	private static ClassNode BOM = ClassHelper.make(DependencyManagementBom.class);
+
+	@Override
+	public void visit(ASTNode[] nodes, SourceUnit source) {
+		for (ASTNode astNode : nodes) {
+			if (astNode instanceof ModuleNode) {
+				visitModule((ModuleNode) astNode, getBomModule());
+			}
+		}
+	}
+
+	/**
+	 * The bom to be added to dependency management in compact form:
+	 * <code>"&lt;groupId&gt;:&lt;artifactId&gt;:&lt;version&gt;"</code> (like in a
+	 * <code>@Grab</code>).
+	 *
+	 * @return the maven co-ordinates of the bom to add
+	 */
+	abstract protected String getBomModule();
+
+	private void visitModule(ModuleNode node, String module) {
+		addDependencyManagementBom(node, module);
+	}
+
+	private void addDependencyManagementBom(ModuleNode node, String module) {
+		AnnotatedNode annotated = getAnnotatedNode(node);
+		if (annotated != null) {
+			AnnotationNode bom = getAnnotation(annotated);
+			List<Expression> expressions = new ArrayList<Expression>(
+					getConstantExpressions(bom.getMember("value")));
+			expressions.add(new ConstantExpression(module));
+			bom.setMember("value", new ListExpression(expressions));
+		}
+	}
+
+	private AnnotationNode getAnnotation(AnnotatedNode annotated) {
+		AnnotationNode annotation;
+		List<AnnotationNode> annotations = annotated.getAnnotations(BOM);
+		if (annotations.isEmpty()) {
+			annotation = new AnnotationNode(BOM);
+			annotated.addAnnotation(annotation);
+		}
+		else {
+			annotation = annotations.get(0);
+		}
+		return annotation;
+	}
+
+	private AnnotatedNode getAnnotatedNode(ModuleNode node) {
+		PackageNode pkg = node.getPackage();
+		if (pkg != null) {
+			if (!pkg.getAnnotations(BOM).isEmpty()) {
+				return pkg;
+			}
+		}
+		if (!node.getClasses().isEmpty()) {
+			ClassNode cls = node.getClasses().get(0);
+			return cls;
+		}
+		return pkg;
+	}
+
+	private List<ConstantExpression> getConstantExpressions(Expression valueExpression) {
+		if (valueExpression instanceof ListExpression) {
+			return getConstantExpressions((ListExpression) valueExpression);
+		}
+		if (valueExpression instanceof ConstantExpression
+				&& ((ConstantExpression) valueExpression).getValue() instanceof String) {
+			return Arrays.asList((ConstantExpression) valueExpression);
+		}
+		return Collections.emptyList();
+	}
+
+	private List<ConstantExpression> getConstantExpressions(
+			ListExpression valueExpression) {
+		List<ConstantExpression> expressions = new ArrayList<ConstantExpression>();
+		for (Expression expression : valueExpression.getExpressions()) {
+			if (expression instanceof ConstantExpression
+					&& ((ConstantExpression) expression).getValue() instanceof String) {
+				expressions.add((ConstantExpression) expression);
+			}
+		}
+		return expressions;
+	}
+
+}