| // 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.collect.Iterables; |
| import com.google.devtools.build.lib.events.Location; |
| import com.google.devtools.build.lib.syntax.FuncallExpression.MethodDescriptor; |
| 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.VariableScope; |
| |
| import net.bytebuddy.implementation.bytecode.ByteCodeAppender; |
| import net.bytebuddy.implementation.bytecode.Duplication; |
| import net.bytebuddy.implementation.bytecode.constant.TextConstant; |
| |
| import java.util.ArrayList; |
| import java.util.List; |
| |
| /** |
| * Syntax node for a dot expression. |
| * e.g. obj.field, but not obj.method() |
| */ |
| public final class DotExpression extends Expression { |
| |
| private final Expression obj; |
| |
| private final Identifier field; |
| |
| public DotExpression(Expression obj, Identifier field) { |
| this.obj = obj; |
| this.field = field; |
| } |
| |
| public Expression getObj() { |
| return obj; |
| } |
| |
| public Identifier getField() { |
| return field; |
| } |
| |
| @Override |
| public String toString() { |
| return obj + "." + field; |
| } |
| |
| @Override |
| Object doEval(Environment env) throws EvalException, InterruptedException { |
| Object objValue = obj.eval(env); |
| String name = field.getName(); |
| Object result = eval(objValue, name, getLocation(), env); |
| return checkResult(objValue, result, name, getLocation()); |
| } |
| |
| /** |
| * Throws the correct error message if the result is null depending on the objValue. |
| */ |
| public static Object checkResult(Object objValue, Object result, String name, Location loc) |
| throws EvalException { |
| if (result == null) { |
| if (objValue instanceof ClassObject) { |
| String customErrorMessage = ((ClassObject) objValue).errorMessage(name); |
| if (customErrorMessage != null) { |
| throw new EvalException(loc, customErrorMessage); |
| } |
| } |
| throw new EvalException( |
| loc, |
| Printer.format( |
| "Object of type '%s' has no field %r", EvalUtils.getDataTypeName(objValue), name)); |
| } |
| return result; |
| } |
| |
| /** |
| * Returns the field of the given name of the struct objValue, or null if no such field exists. |
| */ |
| public static Object eval(Object objValue, String name, |
| Location loc, Environment env) throws EvalException { |
| if (objValue instanceof ClassObject) { |
| Object result = null; |
| try { |
| result = ((ClassObject) objValue).getValue(name); |
| } catch (IllegalArgumentException ex) { |
| throw new EvalException(loc, ex); |
| } |
| // ClassObjects may have fields that are annotated with @SkylarkCallable. |
| // Since getValue() does not know about those, we cannot expect that result is a valid object. |
| if (result != null) { |
| result = SkylarkType.convertToSkylark(result, env); |
| // If we access NestedSets using ClassObject.getValue() we won't know the generic type, |
| // so we have to disable it. This should not happen. |
| SkylarkType.checkTypeAllowedInSkylark(result, loc); |
| return result; |
| } |
| } |
| |
| List<MethodDescriptor> methods = |
| FuncallExpression.getMethods(objValue.getClass(), name, 0, loc); |
| if (methods != null && !methods.isEmpty()) { |
| MethodDescriptor method = Iterables.getOnlyElement(methods); |
| if (method.getAnnotation().structField()) { |
| return FuncallExpression.callMethod(method, name, objValue, new Object[] {}, loc, env); |
| } |
| } |
| |
| return null; |
| } |
| |
| @Override |
| public void accept(SyntaxTreeVisitor visitor) { |
| visitor.visit(this); |
| } |
| |
| @Override |
| void validate(ValidationEnvironment env) throws EvalException { |
| obj.validate(env); |
| } |
| |
| @Override |
| ByteCodeAppender compile(VariableScope scope, DebugInfo debugInfo) throws EvalException { |
| List<ByteCodeAppender> code = new ArrayList<>(); |
| code.add(obj.compile(scope, debugInfo)); |
| TextConstant name = new TextConstant(field.getName()); |
| ByteCodeUtils.append( |
| code, |
| Duplication.SINGLE, |
| name, |
| debugInfo.add(this).loadLocation, |
| scope.loadEnvironment(), |
| ByteCodeUtils.invoke( |
| DotExpression.class, |
| "eval", |
| Object.class, |
| String.class, |
| Location.class, |
| Environment.class), |
| // at this point we have the value of obj and the result of eval on the stack |
| name, |
| debugInfo.add(this).loadLocation, |
| ByteCodeUtils.invoke( |
| DotExpression.class, |
| "checkResult", |
| Object.class, |
| Object.class, |
| String.class, |
| Location.class)); |
| return ByteCodeUtils.compoundAppender(code); |
| } |
| } |