| // 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 com.google.common.base.Optional; |
| import com.google.devtools.build.lib.syntax.compiler.DebugInfo; |
| import com.google.devtools.build.lib.syntax.compiler.LoopLabels; |
| import com.google.devtools.build.lib.syntax.compiler.VariableScope; |
| |
| import net.bytebuddy.implementation.bytecode.ByteCodeAppender; |
| |
| /** |
| * Base class for all statements nodes in the AST. |
| */ |
| public abstract class Statement extends ASTNode { |
| |
| /** |
| * Executes the statement in the specified build environment, which may be |
| * modified. |
| * |
| * @throws EvalException if execution of the statement could not be completed. |
| * @throws InterruptedException may be thrown in a sub class. |
| */ |
| final void exec(Environment env) throws EvalException, InterruptedException { |
| try { |
| doExec(env); |
| } catch (EvalException | RuntimeException ex) { |
| throw handleException(ex); |
| } |
| } |
| |
| /** |
| * Executes the statement. |
| * |
| * <p>This method is only invoked by the super class {@link Statement} when calling {@link |
| * #exec(Environment)}. |
| * |
| * @throws EvalException if execution of the statement could not be completed. |
| * @throws InterruptedException may be thrown in a sub class. |
| */ |
| abstract void doExec(Environment env) throws EvalException, InterruptedException; |
| |
| /** |
| * Checks the semantics of the Statement using the Environment according to |
| * the rules of the Skylark language. The Environment can be used e.g. to check |
| * variable type collision, read only variables, detecting recursion, existence of |
| * built-in variables, functions, etc. |
| * |
| * <p>The semantical check should be performed after the Skylark extension is loaded |
| * (i.e. is syntactically correct) and before is executed. The point of the semantical check |
| * is to make sure (as much as possible) that no error can occur during execution (Skylark |
| * programmers get a "compile time" error). It should also check execution branches (e.g. in |
| * if statements) that otherwise might never get executed. |
| * |
| * @throws EvalException if the Statement has a semantical error. |
| */ |
| abstract void validate(ValidationEnvironment env) throws EvalException; |
| |
| /** |
| * Builds a {@link ByteCodeAppender} that implements this statement. |
| * |
| * <p>A statement implementation should never require any particular state of the byte code |
| * stack and should leave it in the state it was before. |
| * |
| * @throws EvalException for any error that would have occurred during evaluation of the |
| * function definition that contains this statement, e.g. type errors. |
| */ |
| ByteCodeAppender compile( |
| VariableScope scope, Optional<LoopLabels> loopLabels, DebugInfo debugInfo) |
| throws EvalException { |
| throw new UnsupportedOperationException(this.getClass().getSimpleName() + " unsupported."); |
| } |
| } |