| // Copyright 2014 The Bazel Authors. All rights reserved. |
| // |
| // Licensed under the Apache License, Version 2.0 (the "License"); |
| // you may not use this file except in compliance with the License. |
| // You may obtain a copy of the License at |
| // |
| // http://www.apache.org/licenses/LICENSE-2.0 |
| // |
| // Unless required by applicable law or agreed to in writing, software |
| // distributed under the License is distributed on an "AS IS" BASIS, |
| // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| // See the License for the specific language governing permissions and |
| // limitations under the License. |
| package com.google.devtools.build.lib.syntax; |
| |
| import static com.google.devtools.build.lib.syntax.compiler.ByteCodeUtils.append; |
| |
| import com.google.common.base.Optional; |
| import com.google.common.collect.ImmutableList; |
| import com.google.devtools.build.lib.syntax.compiler.ByteCodeUtils; |
| import com.google.devtools.build.lib.syntax.compiler.DebugInfo; |
| import com.google.devtools.build.lib.syntax.compiler.Jump; |
| import com.google.devtools.build.lib.syntax.compiler.Jump.PrimitiveComparison; |
| import com.google.devtools.build.lib.syntax.compiler.LabelAdder; |
| import com.google.devtools.build.lib.syntax.compiler.LoopLabels; |
| import com.google.devtools.build.lib.syntax.compiler.VariableScope; |
| import com.google.devtools.build.lib.util.Preconditions; |
| |
| import net.bytebuddy.implementation.bytecode.ByteCodeAppender; |
| |
| import java.util.ArrayList; |
| import java.util.List; |
| |
| /** |
| * Syntax node for an if/else statement. |
| */ |
| public final class IfStatement extends Statement { |
| |
| /** |
| * Syntax node for an [el]if statement. |
| */ |
| static final class ConditionalStatements extends Statement { |
| |
| private final Expression condition; |
| private final ImmutableList<Statement> stmts; |
| |
| public ConditionalStatements(Expression condition, List<Statement> stmts) { |
| this.condition = Preconditions.checkNotNull(condition); |
| this.stmts = ImmutableList.copyOf(stmts); |
| } |
| |
| @Override |
| void doExec(Environment env) throws EvalException, InterruptedException { |
| for (Statement stmt : stmts) { |
| stmt.exec(env); |
| } |
| } |
| |
| @Override |
| public String toString() { |
| return "[el]if " + condition + ": " + stmts + "\n"; |
| } |
| |
| @Override |
| public void accept(SyntaxTreeVisitor visitor) { |
| visitor.visit(this); |
| } |
| |
| Expression getCondition() { |
| return condition; |
| } |
| |
| ImmutableList<Statement> getStmts() { |
| return stmts; |
| } |
| |
| @Override |
| void validate(ValidationEnvironment env) throws EvalException { |
| condition.validate(env); |
| validateStmts(env, stmts); |
| } |
| |
| @Override |
| ByteCodeAppender compile( |
| VariableScope scope, Optional<LoopLabels> loopLabels, DebugInfo debugInfo) |
| throws EvalException { |
| List<ByteCodeAppender> code = new ArrayList<>(); |
| for (Statement statement : stmts) { |
| code.add(statement.compile(scope, loopLabels, debugInfo)); |
| } |
| return ByteCodeUtils.compoundAppender(code); |
| } |
| } |
| |
| private final ImmutableList<ConditionalStatements> thenBlocks; |
| private final ImmutableList<Statement> elseBlock; |
| |
| /** |
| * Constructs a if-elif-else statement. The else part is mandatory, but the list may be empty. |
| * ThenBlocks has to have at least one element. |
| */ |
| IfStatement(List<ConditionalStatements> thenBlocks, List<Statement> elseBlock) { |
| Preconditions.checkArgument(!thenBlocks.isEmpty()); |
| this.thenBlocks = ImmutableList.copyOf(thenBlocks); |
| this.elseBlock = ImmutableList.copyOf(elseBlock); |
| } |
| |
| public ImmutableList<ConditionalStatements> getThenBlocks() { |
| return thenBlocks; |
| } |
| |
| public ImmutableList<Statement> getElseBlock() { |
| return elseBlock; |
| } |
| |
| @Override |
| public String toString() { |
| // TODO(bazel-team): if we want to print the complete statement, the function |
| // needs an extra argument to specify indentation level. |
| // As guaranteed by the constructor, there must be at least one element in thenBlocks. |
| return String.format("if %s:\n", thenBlocks.get(0).getCondition()); |
| } |
| |
| @Override |
| void doExec(Environment env) throws EvalException, InterruptedException { |
| for (ConditionalStatements stmt : thenBlocks) { |
| if (EvalUtils.toBoolean(stmt.getCondition().eval(env))) { |
| stmt.exec(env); |
| return; |
| } |
| } |
| for (Statement stmt : elseBlock) { |
| stmt.exec(env); |
| } |
| } |
| |
| @Override |
| public void accept(SyntaxTreeVisitor visitor) { |
| visitor.visit(this); |
| } |
| |
| @Override |
| void validate(ValidationEnvironment env) throws EvalException { |
| env.startTemporarilyDisableReadonlyCheckSession(); |
| for (ConditionalStatements stmts : thenBlocks) { |
| stmts.validate(env); |
| } |
| validateStmts(env, elseBlock); |
| env.finishTemporarilyDisableReadonlyCheckSession(); |
| } |
| |
| private static void validateStmts(ValidationEnvironment env, List<Statement> stmts) |
| throws EvalException { |
| for (Statement stmt : stmts) { |
| stmt.validate(env); |
| } |
| env.finishTemporarilyDisableReadonlyCheckBranch(); |
| } |
| |
| @Override |
| ByteCodeAppender compile( |
| VariableScope scope, Optional<LoopLabels> loopLabels, DebugInfo debugInfo) |
| throws EvalException { |
| List<ByteCodeAppender> code = new ArrayList<>(); |
| LabelAdder after = new LabelAdder(); |
| LabelAdder nextConditionalOrElse; |
| for (ConditionalStatements statement : thenBlocks) { |
| nextConditionalOrElse = new LabelAdder(); |
| // compile condition and convert to boolean |
| code.add(statement.getCondition().compile(scope, debugInfo)); |
| append( |
| code, |
| EvalUtils.toBoolean, |
| // jump to next conditional/else block if false |
| Jump.ifIntOperandToZero(PrimitiveComparison.EQUAL).to(nextConditionalOrElse)); |
| // otherwise execute the body and jump to end |
| code.add(statement.compile(scope, loopLabels, debugInfo)); |
| append(code, Jump.to(after)); |
| // add label for next conditional or the else block (which may be empty, but no matter) |
| append(code, nextConditionalOrElse); |
| } |
| for (Statement statement : elseBlock) { |
| code.add(statement.compile(scope, loopLabels, debugInfo)); |
| } |
| append(code, after); |
| |
| return ByteCodeUtils.compoundAppender(code); |
| } |
| } |