Java tutorial
/******************************************************************************* * Copyright (c) 2000, 2014 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 349326 - [1.7] new warning for missing try-with-resources * bug 368546 - [compiler][resource] Avoid remaining false positives found when compiling the Eclipse SDK * bug 345305 - [compiler][null] Compiler misidentifies a case of "variable can only be null" * bug 383368 - [compiler][null] syntactic null analysis for field references * bug 402993 - [null] Follow up of bug 401088: Missing warning about redundant null check * Bug 440282 - [resource] Resource leak detection false negative with empty finally block *******************************************************************************/ 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 Block extends Statement { public Statement[] statements; public int explicitDeclarations; // the number of explicit declaration , used to create scope public BlockScope scope; public Block(int explicitDeclarations) { this.explicitDeclarations = explicitDeclarations; } @Override public FlowInfo analyseCode(BlockScope currentScope, FlowContext flowContext, FlowInfo flowInfo) { // empty block if (this.statements == null) return flowInfo; int complaintLevel = (flowInfo.reachMode() & FlowInfo.UNREACHABLE) != 0 ? Statement.COMPLAINED_FAKE_REACHABLE : Statement.NOT_COMPLAINED; boolean enableSyntacticNullAnalysisForFields = currentScope .compilerOptions().enableSyntacticNullAnalysisForFields; for (int i = 0, max = this.statements.length; i < max; i++) { Statement stat = this.statements[i]; if ((complaintLevel = stat.complainIfUnreachable(flowInfo, this.scope, complaintLevel, true)) < Statement.COMPLAINED_UNREACHABLE) { flowInfo = stat.analyseCode(this.scope, flowContext, flowInfo); } // record the effect of stat on the finally block of an enclosing try-finally, if any: flowContext.mergeFinallyNullInfo(flowInfo); if (enableSyntacticNullAnalysisForFields) { flowContext.expireNullCheckedFieldInfo(); } } if (this.scope != currentScope) { // if block is tracking any resources other than the enclosing 'currentScope', analyse them now: this.scope.checkUnclosedCloseables(flowInfo, flowContext, null, null); } if (this.explicitDeclarations > 0) { // cleanup assignment info for locals that are scoped to this block: LocalVariableBinding[] locals = this.scope.locals; if (locals != null) { int numLocals = this.scope.localIndex; for (int i = 0; i < numLocals; i++) { flowInfo.resetAssignmentInfo(locals[i]); } } } return flowInfo; } /** * Code generation for a block */ @Override public void generateCode(BlockScope currentScope, CodeStream codeStream) { if ((this.bits & IsReachable) == 0) { return; } int pc = codeStream.position; if (this.statements != null) { for (int i = 0, max = this.statements.length; i < max; i++) { this.statements[i].generateCode(this.scope, codeStream); } } // for local variable debug attributes if (this.scope != currentScope) { // was really associated with its own scope codeStream.exitUserScope(this.scope); } codeStream.recordPositionsFrom(pc, this.sourceStart); } @Override public boolean isEmptyBlock() { return this.statements == null; } public StringBuffer printBody(int indent, StringBuffer output) { if (this.statements == null) return output; for (int i = 0; i < this.statements.length; i++) { this.statements[i].printStatement(indent + 1, output); output.append('\n'); } return output; } @Override public StringBuffer printStatement(int indent, StringBuffer output) { printIndent(indent, output); output.append("{\n"); //$NON-NLS-1$ printBody(indent, output); return printIndent(indent, output).append('}'); } @Override public void resolve(BlockScope upperScope) { if ((this.bits & UndocumentedEmptyBlock) != 0) { upperScope.problemReporter().undocumentedEmptyBlock(this.sourceStart, this.sourceEnd); } if (this.statements != null) { this.scope = this.explicitDeclarations == 0 ? upperScope : new BlockScope(upperScope, this.explicitDeclarations); for (int i = 0, length = this.statements.length; i < length; i++) { this.statements[i].resolve(this.scope); } } } public void resolveUsing(BlockScope givenScope) { if ((this.bits & UndocumentedEmptyBlock) != 0) { givenScope.problemReporter().undocumentedEmptyBlock(this.sourceStart, this.sourceEnd); } // this optimized resolve(...) is sent only on none empty blocks this.scope = givenScope; if (this.statements != null) { for (int i = 0, length = this.statements.length; i < length; i++) { this.statements[i].resolve(this.scope); } } } @Override public void traverse(ASTVisitor visitor, BlockScope blockScope) { if (visitor.visit(this, blockScope)) { if (this.statements != null) { for (int i = 0, length = this.statements.length; i < length; i++) this.statements[i].traverse(visitor, this.scope); } } visitor.endVisit(this, blockScope); } /** * Dispatch the call on its last statement. */ @Override public void branchChainTo(BranchLabel label) { if (this.statements != null) { this.statements[this.statements.length - 1].branchChainTo(label); } } // A block does not complete normally if the last statement which we presume is reachable does not complete normally. @Override public boolean doesNotCompleteNormally() { int length = this.statements == null ? 0 : this.statements.length; return length > 0 && this.statements[length - 1].doesNotCompleteNormally(); } @Override public boolean completesByContinue() { int length = this.statements == null ? 0 : this.statements.length; return length > 0 && this.statements[length - 1].completesByContinue(); } }