// 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; /** * 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 ex) { throw maybeTransformException(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; }