Added @NonNull on parameters feature (issue 514),

including docs and changelog.

1 files changed, 148 insertions, 0 deletions

diff --git a/src/core/lombok/javac/handlers/NonNullHandler.java b/src/core/lombok/javac/handlers/NonNullHandler.java
new file mode 100644
index 00000000..415d6032
--- /dev/null
+++ b/src/core/lombok/javac/handlers/NonNullHandler.java
@@ -0,0 +1,148 @@
+/*
+ * Copyright (C) 2013 The Project Lombok Authors.
+ * 
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ * 
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ * 
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+ * THE SOFTWARE.
+ */
+package lombok.javac.handlers;
+
+import static lombok.javac.Javac.*;
+import static lombok.javac.handlers.JavacHandlerUtil.*;
+
+import org.mangosdk.spi.ProviderFor;
+
+import com.sun.tools.javac.tree.JCTree.JCAnnotation;
+import com.sun.tools.javac.tree.JCTree.JCBinary;
+import com.sun.tools.javac.tree.JCTree.JCBlock;
+import com.sun.tools.javac.tree.JCTree.JCExpression;
+import com.sun.tools.javac.tree.JCTree.JCIdent;
+import com.sun.tools.javac.tree.JCTree.JCIf;
+import com.sun.tools.javac.tree.JCTree.JCLiteral;
+import com.sun.tools.javac.tree.JCTree.JCMethodDecl;
+import com.sun.tools.javac.tree.JCTree.JCParens;
+import com.sun.tools.javac.tree.JCTree.JCStatement;
+import com.sun.tools.javac.tree.JCTree.JCThrow;
+import com.sun.tools.javac.tree.JCTree.JCVariableDecl;
+import com.sun.tools.javac.util.List;
+
+import lombok.NonNull;
+import lombok.core.AnnotationValues;
+import lombok.core.AST.Kind;
+import lombok.javac.JavacAnnotationHandler;
+import lombok.javac.JavacNode;
+
+@ProviderFor(JavacAnnotationHandler.class)
+public class NonNullHandler extends JavacAnnotationHandler<NonNull> {
+	@Override public void handle(AnnotationValues<NonNull> annotation, JCAnnotation ast, JavacNode annotationNode) {
+		if (annotationNode.up().getKind() == Kind.FIELD) {
+			// This is meaningless unless the field is used to generate a method (@Setter, @RequiredArgsConstructor, etc),
+			// but in that case those handlers will take care of it. However, we DO check if the annotation is applied to
+			// a primitive, because those handlers trigger on any annotation named @NonNull and we only want the warning
+			// behaviour on _OUR_ 'lombok.NonNull'.
+			
+			try {
+				if (isPrimitive(((JCVariableDecl) annotationNode.up().get()).vartype)) {
+					annotationNode.addWarning("@NonNull is meaningless on a primitive.");
+				}
+			} catch (Exception ignore) {}
+			
+			return;
+		}
+		
+		if (annotationNode.up().getKind() != Kind.ARGUMENT) return;
+		
+		JCMethodDecl declaration;
+		
+		try {
+			declaration = (JCMethodDecl) annotationNode.up().up().get();
+		} catch (Exception e) {
+			return;
+		}
+		
+		if (JavacHandlerUtil.isGenerated(declaration)) return;
+		
+		// Possibly, if 'declaration instanceof ConstructorDeclaration', fetch declaration.constructorCall, search it for any references to our parameter,
+		// and if they exist, create a new method in the class: 'private static <T> T lombok$nullCheck(T expr, String msg) {if (expr == null) throw NPE; return expr;}' and
+		// wrap all references to it in the super/this to a call to this method.
+		
+		JCStatement nullCheck = recursiveSetGeneratedBy(generateNullCheck(annotationNode.getTreeMaker(), annotationNode.up()), ast);
+		
+		if (nullCheck == null) {
+			// @NonNull applied to a primitive. Kinda pointless. Let's generate a warning.
+			annotationNode.addWarning("@NonNull is meaningless on a primitive.");
+			return;
+		}
+		
+		List<JCStatement> statements = declaration.body.stats;
+		
+		String expectedName = annotationNode.up().getName();
+		for (JCStatement stat : statements) {
+			if (JavacHandlerUtil.isConstructorCall(stat)) continue;
+			String varNameOfNullCheck = returnVarNameIfNullCheck(stat);
+			if (varNameOfNullCheck == null) break;
+			if (varNameOfNullCheck.equals(expectedName)) return;
+		}
+		
+		List<JCStatement> tail = statements;
+		List<JCStatement> head = List.nil();
+		for (JCStatement stat : statements) {
+			if (JavacHandlerUtil.isConstructorCall(stat) || JavacHandlerUtil.isGenerated(stat)) {
+				tail = tail.tail;
+				head = head.prepend(stat);
+				continue;
+			}
+			break;
+		}
+		
+		List<JCStatement> newList = tail.prepend(nullCheck);
+		for (JCStatement stat : head) newList = newList.prepend(stat);
+		declaration.body.stats = newList;
+	}
+	
+	/**
+	 * Checks if the statement is of the form 'if (x == null) {throw WHATEVER;},
+	 * where the block braces are optional. If it is of this form, returns "x".
+	 * If it is not of this form, returns null.
+	 */
+	private String returnVarNameIfNullCheck(JCStatement stat) {
+		if (!(stat instanceof JCIf)) return null;
+		
+		/* Check that the if's statement is a throw statement, possibly in a block. */ {
+			JCStatement then = ((JCIf) stat).thenpart;
+			if (then instanceof JCBlock) {
+				List<JCStatement> stats = ((JCBlock) then).stats;
+				if (stats.length() == 0) return null;
+				then = stats.get(0);
+			}
+			if (!(then instanceof JCThrow)) return null;
+		}
+		
+		/* Check that the if's conditional is like 'x == null'. Return from this method (don't generate
+		   a nullcheck) if 'x' is equal to our own variable's name: There's already a nullcheck here. */ {
+			JCExpression cond = ((JCIf) stat).cond;
+			while (cond instanceof JCParens) cond = ((JCParens) cond).expr;
+			if (!(cond instanceof JCBinary)) return null;
+			JCBinary bin = (JCBinary) cond;
+			if (getTag(bin) != CTC_EQUAL) return null;
+			if (!(bin.lhs instanceof JCIdent)) return null;
+			if (!(bin.rhs instanceof JCLiteral)) return null;
+			if (((JCLiteral) bin.rhs).typetag != CTC_BOT) return null;
+			return ((JCIdent) bin.lhs).name.toString();
+		}
+	}
+}