--- /dev/null
+/*******************************************************************************
+ * Copyright (c) 2000, 2004 IBM Corporation and others.
+ * All rights reserved. This program and the accompanying materials
+ * are made available under the terms of the Common Public License v1.0
+ * which accompanies this distribution, and is available at
+ * http://www.eclipse.org/legal/cpl-v10.html
+ *
+ * Contributors:
+ * IBM Corporation - initial API and implementation
+ * Genady Beriozkin - added support for reporting assignment with no effect
+ *******************************************************************************/
+package org.eclipse.jdt.internal.compiler.ast;
+
+import org.eclipse.jdt.internal.compiler.ASTVisitor;
+import org.eclipse.jdt.internal.compiler.codegen.*;
+import org.eclipse.jdt.internal.compiler.flow.*;
+import org.eclipse.jdt.internal.compiler.lookup.*;
+
+public class Assignment extends Expression {
+
+ public Expression lhs;
+ public Expression expression;
+
+ public Assignment(Expression lhs, Expression expression, int sourceEnd) {
+ //lhs is always a reference by construction ,
+ //but is build as an expression ==> the checkcast cannot fail
+
+ this.lhs = lhs;
+ lhs.bits |= IsStrictlyAssignedMASK; // tag lhs as assigned
+
+ this.expression = expression;
+
+ this.sourceStart = lhs.sourceStart;
+ this.sourceEnd = sourceEnd;
+ }
+
+ public FlowInfo analyseCode(
+ BlockScope currentScope,
+ FlowContext flowContext,
+ FlowInfo flowInfo) {
+ // record setting a variable: various scenarii are possible, setting an array reference,
+ // a field reference, a blank final field reference, a field of an enclosing instance or
+ // just a local variable.
+
+ return ((Reference) lhs)
+ .analyseAssignment(currentScope, flowContext, flowInfo, this, false)
+ .unconditionalInits();
+ }
+
+ void checkAssignmentEffect(BlockScope scope) {
+
+ Binding left = getDirectBinding(this.lhs);
+ if (left != null && left == getDirectBinding(this.expression)) {
+ scope.problemReporter().assignmentHasNoEffect(this, left.shortReadableName());
+ this.bits |= IsAssignmentWithNoEffectMASK; // record assignment has no effect
+ }
+ }
+
+ public void generateCode(
+ BlockScope currentScope,
+ CodeStream codeStream,
+ boolean valueRequired) {
+
+ // various scenarii are possible, setting an array reference,
+ // a field reference, a blank final field reference, a field of an enclosing instance or
+ // just a local variable.
+
+ int pc = codeStream.position;
+ if ((this.bits & IsAssignmentWithNoEffectMASK) != 0) {
+ if (valueRequired) {
+ this.expression.generateCode(currentScope, codeStream, true);
+ }
+ } else {
+ ((Reference) lhs).generateAssignment(currentScope, codeStream, this, valueRequired);
+ // variable may have been optimized out
+ // the lhs is responsible to perform the implicitConversion generation for the assignment since optimized for unused local assignment.
+ }
+ codeStream.recordPositionsFrom(pc, this.sourceStart);
+ }
+
+ Binding getDirectBinding(Expression someExpression) {
+ if (someExpression instanceof SingleNameReference) {
+ return ((SingleNameReference)someExpression).binding;
+ } else if (someExpression instanceof FieldReference) {
+ FieldReference fieldRef = (FieldReference)someExpression;
+ if (fieldRef.receiver.isThis() && !(fieldRef.receiver instanceof QualifiedThisReference)) {
+ return fieldRef.binding;
+ }
+ }
+ return null;
+ }
+ public StringBuffer print(int indent, StringBuffer output) {
+
+ //no () when used as a statement
+ printIndent(indent, output);
+ return printExpressionNoParenthesis(indent, output);
+ }
+ public StringBuffer printExpression(int indent, StringBuffer output) {
+
+ //subclass redefine printExpressionNoParenthesis()
+ output.append('(');
+ return printExpressionNoParenthesis(0, output).append(')');
+ }
+
+ public StringBuffer printExpressionNoParenthesis(int indent, StringBuffer output) {
+
+ lhs.printExpression(indent, output).append(" = "); //$NON-NLS-1$
+ return expression.printExpression(0, output);
+ }
+
+ public StringBuffer printStatement(int indent, StringBuffer output) {
+
+ //no () when used as a statement
+ return print(indent, output).append(';');
+ }
+
+ public TypeBinding resolveType(BlockScope scope) {
+
+ // due to syntax lhs may be only a NameReference, a FieldReference or an ArrayReference
+ constant = NotAConstant;
+ if (!(this.lhs instanceof Reference) || this.lhs.isThis()) {
+ scope.problemReporter().expressionShouldBeAVariable(this.lhs);
+ return null;
+ }
+ this.resolvedType = lhs.resolveType(scope); // expressionType contains the assignment type (lhs Type)
+ TypeBinding rhsType = expression.resolveType(scope);
+ if (this.resolvedType == null || rhsType == null) {
+ return null;
+ }
+ checkAssignmentEffect(scope);
+
+ // Compile-time conversion of base-types : implicit narrowing integer into byte/short/character
+ // may require to widen the rhs expression at runtime
+ if ((expression.isConstantValueOfTypeAssignableToType(rhsType, this.resolvedType)
+ || (this.resolvedType.isBaseType() && BaseTypeBinding.isWidening(this.resolvedType.id, rhsType.id)))
+ || rhsType.isCompatibleWith(this.resolvedType)) {
+ expression.implicitWidening(this.resolvedType, rhsType);
+ return this.resolvedType;
+ }
+ scope.problemReporter().typeMismatchErrorActualTypeExpectedType(
+ expression,
+ rhsType,
+ this.resolvedType);
+ return this.resolvedType;
+ }
+ /* (non-Javadoc)
+ * @see org.eclipse.jdt.internal.compiler.ast.Expression#resolveTypeExpecting(org.eclipse.jdt.internal.compiler.lookup.BlockScope, org.eclipse.jdt.internal.compiler.lookup.TypeBinding)
+ */
+ public TypeBinding resolveTypeExpecting(
+ BlockScope scope,
+ TypeBinding expectedType) {
+
+ TypeBinding type = super.resolveTypeExpecting(scope, expectedType);
+ // signal possible accidental boolean assignment (instead of using '==' operator)
+ if (expectedType == BooleanBinding
+ && this.lhs.resolvedType == BooleanBinding
+ && (this.lhs.bits & IsStrictlyAssignedMASK) != 0) {
+ scope.problemReporter().possibleAccidentalBooleanAssignment(this);
+ }
+
+ return type;
+ }
+
+ public void traverse(ASTVisitor visitor, BlockScope scope) {
+
+ if (visitor.visit(this, scope)) {
+ lhs.traverse(visitor, scope);
+ expression.traverse(visitor, scope);
+ }
+ visitor.endVisit(this, scope);
+ }
+}
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projects / org.ibex.tool.git / blobdiff