Moves try-with-resources rewriting into Rewriter.java.

Change on 2017/05/30 by kstanger <kstanger@google.com> ------------- Created by MOE: https://github.com/google/moe MOE_MIGRATED_REVID=157484905
google · May 31, 2017 · 71ecf6b · 71ecf6b
1 parent 7696341
commit 71ecf6b
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Showing 6 changed files with 266 additions and 213 deletions.
diff --git a/translator/src/main/java/com/google/devtools/j2objc/gen/StatementGenerator.java b/translator/src/main/java/com/google/devtools/j2objc/gen/StatementGenerator.java
@@ -292,19 +292,6 @@ public boolean visit(CastExpression node) {
     return false;
   }
 
-  private void printMultiCatch(CatchClause node) {
-    SingleVariableDeclaration exception = node.getException();
-    for (Type exceptionType : ((UnionType) exception.getType()).getTypes()) {
-      buffer.append("@catch (");
-      exceptionType.accept(this);
-      buffer.append(" *");
-      buffer.append(nameTable.getVariableQualifiedName(exception.getVariableElement()));
-      buffer.append(") {\n");
-      printStatements(node.getBody().getStatements());
-      buffer.append("}\n");
-    }
-  }
-
   @Override
   public boolean visit(CharacterLiteral node) {
     buffer.append(UnicodeUtils.escapeCharLiteral(node.charValue()));
@@ -837,24 +824,10 @@ public boolean visit(ThrowStatement node) {
 
   @Override
   public boolean visit(TryStatement node) {
-    List<VariableDeclarationExpression> resources = node.getResources();
+    assert node.getResources().isEmpty() : "try-with-resources is handled by Rewriter.";
-    boolean hasResources = !resources.isEmpty();
-    boolean extendedTryWithResources = hasResources
-        && (!node.getCatchClauses().isEmpty() || node.getFinally() != null);
-
-    if (hasResources && !extendedTryWithResources) {
-      printBasicTryWithResources(node.getBody(), resources);
-      return false;
-    }
 
     buffer.append("@try ");
-    if (extendedTryWithResources) {
+    node.getBody().accept(this);
-      // Put resources inside the body of this statement (JSL 14.20.3.2).
-      printBasicTryWithResources(node.getBody(), resources);
-    } else {
-      node.getBody().accept(this);
-    }
-    buffer.append(' ');
 
     for (CatchClause cc : node.getCatchClauses()) {
       if (cc.getException().getType() instanceof UnionType) {
@@ -876,54 +849,17 @@ public boolean visit(TryStatement node) {
     return false;
   }
 
-  /**
+  private void printMultiCatch(CatchClause node) {
-   * Print basic try-with-resources, as defined by JLS 14.20.3.1.
+    SingleVariableDeclaration exception = node.getException();
-   */
+    for (Type exceptionType : ((UnionType) exception.getType()).getTypes()) {
-  private void printBasicTryWithResources(Block body,
+      buffer.append("@catch (");
-      List<VariableDeclarationExpression> resources) {
+      exceptionType.accept(this);
-    VariableDeclarationExpression resource = resources.get(0);
+      buffer.append(" *");
-    // Resource declaration can only have one fragment.
+      buffer.append(nameTable.getVariableQualifiedName(exception.getVariableElement()));
-    String resourceName =
+      buffer.append(") {\n");
-        nameTable.getVariableQualifiedName(resource.getFragment(0).getVariableElement());
+      printStatements(node.getBody().getStatements());
-    String primaryExceptionName = UnicodeUtils.format("__primaryException%d", resources.size());
+      buffer.append("}\n");
-
-    buffer.append("{\n");
-    resource.accept(this);
-    buffer.append(";\n");
-    buffer.append(UnicodeUtils.format("NSException *%s = nil;\n", primaryExceptionName));
-
-    buffer.append("@try ");
-    List<VariableDeclarationExpression> tail = resources.subList(1, resources.size());
-    if (tail.isEmpty()) {
-      body.accept(this);
-    } else {
-      printBasicTryWithResources(body, tail);
     }
-
-    buffer.append(UnicodeUtils.format(
-        "@catch (NSException *e) {\n"
-        + "%s = e;\n"
-        + "@throw e;\n"
-        + "}\n", primaryExceptionName));
-
-    buffer.append(UnicodeUtils.format(
-        // Including !=nil in the tests isn't necessary, but makes it easier
-        // to compare to the JLS spec.
-        "@finally {\n"
-        + " if (%s != nil) {\n"
-        + "  if (%s != nil) {\n"
-        + "   @try {\n"
-        + "    [%s close];\n"
-        + "   } @catch (NSException *e) {\n"
-        + "    [%s addSuppressedWithNSException:e];\n"
-        + "   }\n"
-        + "  } else {\n"
-        + "   [%s close];\n"
-        + "  }\n"
-        + " }\n"
-        + "}\n",
-        resourceName, primaryExceptionName, resourceName, primaryExceptionName, resourceName));
-    buffer.append("}\n");
   }
 
   @Override

diff --git a/translator/src/main/java/com/google/devtools/j2objc/translate/NilCheckResolver.java b/translator/src/main/java/com/google/devtools/j2objc/translate/NilCheckResolver.java
@@ -738,6 +738,7 @@ public boolean visit(TryStatement node) {
     pushScope();
     for (CatchClause catchClause : node.getCatchClauses()) {
       scope.mergeDownAndReset();
+      addSafeVar(catchClause.getException().getVariableElement());
       catchClause.accept(this);
     }
     popAndMerge();

diff --git a/translator/src/main/java/com/google/devtools/j2objc/translate/Rewriter.java b/translator/src/main/java/com/google/devtools/j2objc/translate/Rewriter.java
@@ -20,29 +20,41 @@
 import com.google.common.collect.ListMultimap;
 import com.google.devtools.j2objc.ast.AbstractTypeDeclaration;
 import com.google.devtools.j2objc.ast.AnnotationTypeDeclaration;
+import com.google.devtools.j2objc.ast.Assignment;
 import com.google.devtools.j2objc.ast.Block;
 import com.google.devtools.j2objc.ast.BodyDeclaration;
+import com.google.devtools.j2objc.ast.CatchClause;
 import com.google.devtools.j2objc.ast.CompilationUnit;
 import com.google.devtools.j2objc.ast.EnumDeclaration;
 import com.google.devtools.j2objc.ast.Expression;
+import com.google.devtools.j2objc.ast.ExpressionStatement;
 import com.google.devtools.j2objc.ast.FieldAccess;
 import com.google.devtools.j2objc.ast.FieldDeclaration;
 import com.google.devtools.j2objc.ast.ForStatement;
+import com.google.devtools.j2objc.ast.IfStatement;
 import com.google.devtools.j2objc.ast.InfixExpression;
 import com.google.devtools.j2objc.ast.MethodDeclaration;
+import com.google.devtools.j2objc.ast.MethodInvocation;
+import com.google.devtools.j2objc.ast.NullLiteral;
 import com.google.devtools.j2objc.ast.PackageDeclaration;
 import com.google.devtools.j2objc.ast.ParenthesizedExpression;
 import com.google.devtools.j2objc.ast.PropertyAnnotation;
 import com.google.devtools.j2objc.ast.QualifiedName;
+import com.google.devtools.j2objc.ast.SimpleName;
 import com.google.devtools.j2objc.ast.SingleVariableDeclaration;
 import com.google.devtools.j2objc.ast.Statement;
+import com.google.devtools.j2objc.ast.ThrowStatement;
+import com.google.devtools.j2objc.ast.TreeNode;
 import com.google.devtools.j2objc.ast.TreeUtil;
+import com.google.devtools.j2objc.ast.TryStatement;
 import com.google.devtools.j2objc.ast.Type;
 import com.google.devtools.j2objc.ast.TypeDeclaration;
 import com.google.devtools.j2objc.ast.UnitTreeVisitor;
 import com.google.devtools.j2objc.ast.VariableDeclarationExpression;
 import com.google.devtools.j2objc.ast.VariableDeclarationFragment;
 import com.google.devtools.j2objc.ast.VariableDeclarationStatement;
+import com.google.devtools.j2objc.types.ExecutablePair;
+import com.google.devtools.j2objc.types.GeneratedVariableElement;
 import com.google.devtools.j2objc.util.ElementUtil;
 import com.google.devtools.j2objc.util.ErrorUtil;
 import com.google.devtools.j2objc.util.TypeUtil;
@@ -55,6 +67,7 @@
 import javax.lang.model.element.ExecutableElement;
 import javax.lang.model.element.TypeElement;
 import javax.lang.model.element.VariableElement;
+import javax.lang.model.type.DeclaredType;
 import javax.lang.model.type.PrimitiveType;
 import javax.lang.model.type.TypeKind;
 import javax.lang.model.type.TypeMirror;
@@ -374,4 +387,94 @@ public void endVisit(PackageDeclaration node) {
       unit.setHasNullabilityAnnotations();
     }
   }
+
+  @Override
+  public boolean visit(TryStatement node) {
+    // This visit rewrites try-with-resources constructs into regular try statements according to
+    // JLS 14.20.3. The rewriting is done in a visit instead of endVisit because the mutations may
+    // result in more try-with-resources constructs that need to be rewritten recursively.
+    List<VariableDeclarationExpression> resources = node.getResources();
+    if (resources.isEmpty()) {
+      return true;
+    }
+
+    if (!node.getCatchClauses().isEmpty() || node.getFinally() != null) {
+      // Extended try-with-resources. (JLS 14.20.3.2)
+      // The new innerTry statement will be a "Basic try-with-resources" and will be rewritten by
+      // the code below when it is visited.
+      TryStatement innerTry = new TryStatement().setBody(TreeUtil.remove(node.getBody()));;
+      TreeUtil.moveList(resources, innerTry.getResources());
+      node.setBody(new Block().addStatement(innerTry));
+      return true;
+    }
+
+    // Basic try-with-resources. (JLS 14.20.3.1)
+    DeclaredType throwableType = (DeclaredType) typeUtil.getJavaThrowable().asType();
+    VariableElement primaryException = GeneratedVariableElement.newLocalVar(
+        "__primaryException" + resources.size(), throwableType, null);
+
+    List<VariableDeclarationFragment> resourceFrags = resources.remove(0).getFragments();
+    assert resourceFrags.size() == 1;
+    VariableDeclarationFragment resourceFrag = resourceFrags.get(0);
+    VariableElement resourceVar = resourceFrag.getVariableElement();
+
+    DeclaredType closeableType =
+        typeUtil.findSupertype(resourceVar.asType(), "java.lang.AutoCloseable");
+    ExecutablePair closeMethod = typeUtil.findMethod(closeableType, "close");
+    ExecutablePair addSuppressedMethod =
+        typeUtil.findMethod(throwableType, "addSuppressed", "java.lang.Throwable");
+
+    Block block = new Block();
+    block.addStatement(new VariableDeclarationStatement(
+        resourceVar, TreeUtil.remove(resourceFrag.getInitializer())));
+
+    block.addStatement(new VariableDeclarationStatement(
+        primaryException, new NullLiteral(typeUtil.getNull())));
+
+    // If the current try node is the only statement in its parent block then replace the parent
+    // block instead of the try node to avoid extra nesting of braces.
+    TreeNode parent = node.getParent();
+    if (parent instanceof Block && ((Block) parent).getStatements().size() == 1) {
+      parent.replaceWith(block);
+    } else {
+      node.replaceWith(block);
+    }
+    block.addStatement(TreeUtil.remove(node));
+
+    VariableElement caughtException =
+        GeneratedVariableElement.newLocalVar("e", throwableType, null);
+    Block catchBlock = new Block()
+        .addStatement(new ExpressionStatement(new Assignment(
+            new SimpleName(primaryException), new SimpleName(caughtException))))
+        .addStatement(new ThrowStatement(new SimpleName(caughtException)));
+    node.addCatchClause(new CatchClause()
+        .setException(new SingleVariableDeclaration(caughtException))
+        .setBody(catchBlock));
+
+    Statement closeResource = new ExpressionStatement(new MethodInvocation(
+        closeMethod, typeUtil.getVoid(), new SimpleName(resourceVar)));
+    VariableElement suppressedException =
+        GeneratedVariableElement.newLocalVar("e", throwableType, null);
+    node.setFinally(new Block().addStatement(new IfStatement()
+        .setExpression(new InfixExpression(
+            typeUtil.getBoolean(), InfixExpression.Operator.NOT_EQUALS,
+            new SimpleName(resourceVar), new NullLiteral(typeUtil.getNull())))
+        .setThenStatement(new Block().addStatement(new IfStatement()
+            .setExpression(new InfixExpression(
+                typeUtil.getBoolean(), InfixExpression.Operator.NOT_EQUALS,
+                new SimpleName(primaryException), new NullLiteral(typeUtil.getNull())))
+            .setThenStatement(new Block().addStatement(new TryStatement()
+                .setBody(new Block().addStatement(closeResource))
+                .addCatchClause(new CatchClause()
+                    .setException(new SingleVariableDeclaration(suppressedException))
+                    .setBody(new Block().addStatement(new ExpressionStatement(new MethodInvocation(
+                        addSuppressedMethod, typeUtil.getVoid(), new SimpleName(primaryException))
+                        .addArgument(new SimpleName(suppressedException))))))))
+            .setElseStatement(new Block().addStatement(closeResource.copy()))))));
+
+    // Visit the new block instead of the current node because some of content of the node (eg. the
+    // resource initializer) has been moved outside of the try node.
+    block.accept(this);
+    return false;
+  }
 }
diff --git a/translator/src/main/java/com/google/devtools/j2objc/util/TypeUtil.java b/translator/src/main/java/com/google/devtools/j2objc/util/TypeUtil.java
@@ -95,6 +95,7 @@ public final class TypeUtil {
   private final TypeElement javaString;
   private final TypeElement javaClass;
   private final TypeElement javaNumber;
+  private final TypeElement javaThrowable;
 
   private final Map<TypeElement, TypeElement> javaToObjcTypeMap;
 
@@ -109,7 +110,7 @@ public TypeUtil(ParserEnvironment env, ElementUtil elementUtil) {
     javaString = (TypeElement) env.resolve("java.lang.String");
     javaClass = (TypeElement) env.resolve("java.lang.Class");
     javaNumber = (TypeElement) env.resolve("java.lang.Number");
-    TypeElement javaThrowable = (TypeElement) env.resolve("java.lang.Throwable");
+    javaThrowable = (TypeElement) env.resolve("java.lang.Throwable");
     TypeElement javaCloneable = (TypeElement) env.resolve("java.lang.Cloneable");
 
     javaToObjcTypeMap = ImmutableMap.<TypeElement, TypeElement>builder()
@@ -302,6 +303,10 @@ public TypeElement getJavaNumber() {
     return javaNumber;
   }
 
+  public TypeElement getJavaThrowable() {
+    return javaThrowable;
+  }
+
   public boolean isString(TypeElement e) {
     return javaString.equals(e) || NS_STRING.equals(e);
   }