Copyright (c) 2000, 2013 IBM Corporation and others.
This program and the accompanying materials
are made available under the terms of the Eclipse Public License 2.0
which accompanies this distribution, and is available at
https://www.eclipse.org/legal/epl-2.0/
SPDX-License-Identifier: EPL-2.0
Contributors:
    IBM Corporation - initial API and implementation
    Stephan Herrmann - Contributions for
							bug 319201 - [null] no warning when unboxing SingleNameReference causes NPE
							bug 383368 - [compiler][null] syntactic null analysis for field references
							bug 403086 - [compiler][null] include the effect of 'assert' in syntactic null analysis for fields
							bug 403147 - [compiler][null] FUP of bug 400761: consolidate interaction between unboxing, NPE, and deferred checking
							Bug 422796 - [compiler][null] boxed boolean reported as potentially null after null test in lazy disjunction
/*******************************************************************************
 * Copyright (c) 2000, 2013 IBM Corporation and others.
 *
 * This program and the accompanying materials
 * are made available under the terms of the Eclipse Public License 2.0
 * which accompanies this distribution, and is available at
 * https://www.eclipse.org/legal/epl-2.0/
 *
 * SPDX-License-Identifier: EPL-2.0
 *
 * Contributors:
 *     IBM Corporation - initial API and implementation
 *     Stephan Herrmann - Contributions for
 *								bug 319201 - [null] no warning when unboxing SingleNameReference causes NPE
 *								bug 383368 - [compiler][null] syntactic null analysis for field references
 *								bug 403086 - [compiler][null] include the effect of 'assert' in syntactic null analysis for fields
 *								bug 403147 - [compiler][null] FUP of bug 400761: consolidate interaction between unboxing, NPE, and deferred checking
 *								Bug 422796 - [compiler][null] boxed boolean reported as potentially null after null test in lazy disjunction
 *******************************************************************************/
package org.eclipse.jdt.internal.compiler.ast;

import org.eclipse.jdt.internal.compiler.ASTVisitor;
import org.eclipse.jdt.internal.compiler.impl.*;
import org.eclipse.jdt.internal.compiler.codegen.*;
import org.eclipse.jdt.internal.compiler.flow.*;
import org.eclipse.jdt.internal.compiler.lookup.*;

//dedicated treatment for the ||
public class OR_OR_Expression extends BinaryExpression {

	int rightInitStateIndex = -1;
	int mergedInitStateIndex = -1;

	public OR_OR_Expression(Expression left, Expression right, int operator) {
		super(left, right, operator);
	}

	@Override
	public FlowInfo analyseCode(
		BlockScope currentScope,
		FlowContext flowContext,
		FlowInfo flowInfo) {

		Constant cst = this.left.optimizedBooleanConstant();
		boolean isLeftOptimizedTrue = cst != Constant.NotAConstant && cst.booleanValue() == true;
		boolean isLeftOptimizedFalse = cst != Constant.NotAConstant && cst.booleanValue() == false;

		if (isLeftOptimizedFalse) {
			// FALSE || anything
			 // need to be careful of scenario:
			//		(x || y) || !z, if passing the left info to the right, it would be swapped by the !
			FlowInfo mergedInfo = this.left.analyseCode(currentScope, flowContext, flowInfo).unconditionalInits();
			flowContext.expireNullCheckedFieldInfo();
			mergedInfo = this.right.analyseCode(currentScope, flowContext, mergedInfo);
			flowContext.expireNullCheckedFieldInfo();
			this.mergedInitStateIndex =
				currentScope.methodScope().recordInitializationStates(mergedInfo);
			return mergedInfo;
		}

		FlowInfo leftInfo = this.left.analyseCode(currentScope, flowContext, flowInfo);
		if ((flowContext.tagBits & FlowContext.INSIDE_NEGATION) == 0)
			flowContext.expireNullCheckedFieldInfo();

		 // need to be careful of scenario:
		//		(x || y) || !z, if passing the left info to the right, it would be swapped by the !
		FlowInfo rightInfo = leftInfo.initsWhenFalse().unconditionalCopy();
		this.rightInitStateIndex =
			currentScope.methodScope().recordInitializationStates(rightInfo);

		int previousMode = rightInfo.reachMode();
		if (isLeftOptimizedTrue){
			if ((rightInfo.reachMode() & FlowInfo.UNREACHABLE) == 0) {
				currentScope.problemReporter().fakeReachable(this.right);
				rightInfo.setReachMode(FlowInfo.UNREACHABLE_OR_DEAD);
			}
		}
		rightInfo = this.right.analyseCode(currentScope, flowContext, rightInfo);
		if ((flowContext.tagBits & FlowContext.INSIDE_NEGATION) == 0)
			flowContext.expireNullCheckedFieldInfo();
		this.left.checkNPEbyUnboxing(currentScope, flowContext, flowInfo);
		this.right.checkNPEbyUnboxing(currentScope, flowContext, leftInfo.initsWhenFalse());
		// The definitely null variables in right info when true should not be missed out while merging
		// https://bugs.eclipse.org/bugs/show_bug.cgi?id=299900
		FlowInfo leftInfoWhenTrueForMerging = leftInfo.initsWhenTrue().unconditionalCopy().addPotentialInitializationsFrom(rightInfo.unconditionalInitsWithoutSideEffect());
		FlowInfo mergedInfo = FlowInfo.conditional(
					// merging two true initInfos for such a negative case: if ((t && (b = t)) || f) r = b; // b may not have been initialized
				leftInfoWhenTrueForMerging.unconditionalInits().mergedWith(
						rightInfo.safeInitsWhenTrue().setReachMode(previousMode).unconditionalInits()),
					rightInfo.initsWhenFalse());
		this.mergedInitStateIndex =
			currentScope.methodScope().recordInitializationStates(mergedInfo);
		return mergedInfo;
	}

	
Code generation for a binary operation
/**
	 * Code generation for a binary operation
	 */
	@Override
	public void generateCode(BlockScope currentScope, CodeStream codeStream, boolean valueRequired) {
		int pc = codeStream.position;
		if (this.constant != Constant.NotAConstant) {
			// inlined value
			if (valueRequired)
				codeStream.generateConstant(this.constant, this.implicitConversion);
			codeStream.recordPositionsFrom(pc, this.sourceStart);
			return;
		}
		Constant cst = this.right.constant;
		if (cst != Constant.NotAConstant) {
			// <expr> || true --> true
			if (cst.booleanValue() == true) {
				this.left.generateCode(currentScope, codeStream, false);
				if (valueRequired) codeStream.iconst_1();
			} else {
				// <expr>|| false --> <expr>
				this.left.generateCode(currentScope, codeStream, valueRequired);
			}
			if (this.mergedInitStateIndex != -1) {
				codeStream.removeNotDefinitelyAssignedVariables(currentScope, this.mergedInitStateIndex);
			}
			codeStream.generateImplicitConversion(this.implicitConversion);
			codeStream.recordPositionsFrom(pc, this.sourceStart);
			return;
		}

		BranchLabel trueLabel = new BranchLabel(codeStream), endLabel;
		cst = this.left.optimizedBooleanConstant();
		boolean leftIsConst = cst != Constant.NotAConstant;
		boolean leftIsTrue = leftIsConst && cst.booleanValue() == true;

		cst = this.right.optimizedBooleanConstant();
		boolean rightIsConst = cst != Constant.NotAConstant;
		boolean rightIsTrue = rightIsConst && cst.booleanValue() == true;

		generateOperands : {
			if (leftIsConst) {
				this.left.generateCode(currentScope, codeStream, false);
				if (leftIsTrue) {
					break generateOperands; // no need to generate right operand
				}
			} else {
				this.left.generateOptimizedBoolean(currentScope, codeStream, trueLabel, null, true);
				// need value, e.g. if (a == 1 || ((b = 2) > 0)) {} -> shouldn't initialize 'b' if a==1
			}
			if (this.rightInitStateIndex != -1) {
				codeStream.addDefinitelyAssignedVariables(currentScope, this.rightInitStateIndex);
			}
			if (rightIsConst) {
				this.right.generateCode(currentScope, codeStream, false);
			} else {
				this.right.generateOptimizedBoolean(currentScope, codeStream, trueLabel, null, valueRequired);
			}
		}
		if (this.mergedInitStateIndex != -1) {
			codeStream.removeNotDefinitelyAssignedVariables(currentScope, this.mergedInitStateIndex);
		}
		/*
		 * improving code gen for such a case: boolean b = i < 0 || true since
		 * the label has never been used, we have the inlined value on the
		 * stack.
		 */
		if (valueRequired) {
			if (leftIsConst && leftIsTrue) {
				codeStream.iconst_1();
				codeStream.recordPositionsFrom(codeStream.position, this.left.sourceEnd);
			} else {
				if (rightIsConst && rightIsTrue) {
					codeStream.iconst_1();
					codeStream.recordPositionsFrom(codeStream.position, this.left.sourceEnd);
				} else {
					codeStream.iconst_0();
				}
				if (trueLabel.forwardReferenceCount() > 0) {
					if ((this.bits & IsReturnedValue) != 0) {
						codeStream.generateImplicitConversion(this.implicitConversion);
						codeStream.generateReturnBytecode(this);
						trueLabel.place();
						codeStream.iconst_1();
					} else {
						codeStream.goto_(endLabel = new BranchLabel(codeStream));
						codeStream.decrStackSize(1);
						trueLabel.place();
						codeStream.iconst_1();
						endLabel.place();
					}
				} else {
					trueLabel.place();
				}
			}
			codeStream.generateImplicitConversion(this.implicitConversion);
			codeStream.recordPositionsFrom(codeStream.position, this.sourceEnd);
		} else {
			trueLabel.place();
		}
	}

	
Boolean operator code generation Optimized operations are: ||
/**
	 * Boolean operator code generation Optimized operations are: ||
	 */
	@Override
	public void generateOptimizedBoolean(BlockScope currentScope, CodeStream codeStream, BranchLabel trueLabel, BranchLabel falseLabel, boolean valueRequired) {
		if (this.constant != Constant.NotAConstant) {
			super.generateOptimizedBoolean(currentScope, codeStream, trueLabel, falseLabel, valueRequired);
			return;
		}

		// <expr> || false --> <expr>
		Constant cst = this.right.constant;
		if (cst != Constant.NotAConstant && cst.booleanValue() == false) {
			int pc = codeStream.position;
			this.left.generateOptimizedBoolean(currentScope, codeStream, trueLabel, falseLabel, valueRequired);
			if (this.mergedInitStateIndex != -1) {
				codeStream.removeNotDefinitelyAssignedVariables(currentScope, this.mergedInitStateIndex);
			}
			codeStream.recordPositionsFrom(pc, this.sourceStart);
			return;
		}

		cst = this.left.optimizedBooleanConstant();
		boolean leftIsConst = cst != Constant.NotAConstant;
		boolean leftIsTrue = leftIsConst && cst.booleanValue() == true;

		cst = this.right.optimizedBooleanConstant();
		boolean rightIsConst = cst != Constant.NotAConstant;
		boolean rightIsTrue = rightIsConst && cst.booleanValue() == true;

		// default case
		generateOperands : {
			if (falseLabel == null) {
				if (trueLabel != null) {
					// implicit falling through the FALSE case
					this.left.generateOptimizedBoolean(currentScope, codeStream, trueLabel, null, !leftIsConst);
					// need value, e.g. if (a == 1 || ((b = 2) > 0)) {} -> shouldn't initialize 'b' if a==1
					if (leftIsTrue) {
						if (valueRequired) codeStream.goto_(trueLabel);
						codeStream.recordPositionsFrom(codeStream.position, this.left.sourceEnd);
						break generateOperands; // no need to generate right operand
					}
					if (this.rightInitStateIndex != -1) {
						codeStream.addDefinitelyAssignedVariables(currentScope, this.rightInitStateIndex);
					}
					this.right.generateOptimizedBoolean(currentScope, codeStream, trueLabel, null, valueRequired && !rightIsConst);
					if (valueRequired && rightIsTrue) {
						codeStream.goto_(trueLabel);
						codeStream.recordPositionsFrom(codeStream.position, this.sourceEnd);
					}
				}
			} else {
				// implicit falling through the TRUE case
				if (trueLabel == null) {
					BranchLabel internalTrueLabel = new BranchLabel(codeStream);
					this.left.generateOptimizedBoolean(currentScope, codeStream, internalTrueLabel, null, !leftIsConst);
					// need value, e.g. if (a == 1 || ((b = 2) > 0)) {} -> shouldn't initialize 'b' if a==1
					if (leftIsTrue) {
						internalTrueLabel.place();
						break generateOperands; // no need to generate right operand
					}
					if (this.rightInitStateIndex != -1) {
						codeStream
								.addDefinitelyAssignedVariables(currentScope, this.rightInitStateIndex);
					}
					this.right.generateOptimizedBoolean(currentScope, codeStream, null, falseLabel, valueRequired && !rightIsConst);
					int pc = codeStream.position;
					if (valueRequired && rightIsConst && !rightIsTrue) {
						codeStream.goto_(falseLabel);
						codeStream.recordPositionsFrom(pc, this.sourceEnd);
					}
					internalTrueLabel.place();
				} else {
					// no implicit fall through TRUE/FALSE --> should never occur
				}
			}
		}
		if (this.mergedInitStateIndex != -1) {
			codeStream.removeNotDefinitelyAssignedVariables(currentScope, this.mergedInitStateIndex);
		}
	}

	@Override
	public boolean isCompactableOperation() {
		return false;
	}

	
See Also:
resolveType.resolveType(BlockScope)/**
	 * @see org.eclipse.jdt.internal.compiler.ast.BinaryExpression#resolveType(org.eclipse.jdt.internal.compiler.lookup.BlockScope)
	 */
	@Override
	public TypeBinding resolveType(BlockScope scope) {
		TypeBinding result = super.resolveType(scope);
		// check whether comparing identical expressions
		Binding leftDirect = Expression.getDirectBinding(this.left);
		if (leftDirect != null && leftDirect == Expression.getDirectBinding(this.right)) {
			if (!(this.right instanceof Assignment))
				scope.problemReporter().comparingIdenticalExpressions(this);
		}
		return result;
	}

	@Override
	public void traverse(ASTVisitor visitor, BlockScope scope) {
		if (visitor.visit(this, scope)) {
			this.left.traverse(visitor, scope);
			this.right.traverse(visitor, scope);
		}
		visitor.endVisit(this, scope);
	}
}