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// Copyright 2014 Google Inc. 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 java.lang.reflect.InvocationTargetException;
import java.util.List;
import java.util.concurrent.ExecutionException;
/**
* 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 Ident field;
public DotExpression(Expression obj, Ident field) {
this.obj = obj;
this.field = field;
}
public Expression getObj() {
return obj;
}
public Ident getField() {
return field;
}
@Override
public String toString() {
return obj + "." + field;
}
@Override
Object eval(Environment env) throws EvalException, InterruptedException {
Object objValue = obj.eval(env);
String name = field.getName();
Object result = eval(objValue, name, getLocation());
if (result == null) {
if (objValue instanceof ClassObject) {
String customErrorMessage = ((ClassObject) objValue).errorMessage(name);
if (customErrorMessage != null) {
throw new EvalException(getLocation(), customErrorMessage);
}
}
throw new EvalException(getLocation(), "Object of type '"
+ EvalUtils.getDatatypeName(objValue) + "' has no field '" + 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) throws EvalException {
Object result = null;
if (objValue instanceof ClassObject) {
result = ((ClassObject) objValue).getValue(name);
result = SkylarkType.convertToSkylark(result, loc);
// 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);
} else {
try {
List<MethodDescriptor> methods = FuncallExpression.getMethods(objValue.getClass(), name, 0);
if (methods != null && methods.size() > 0) {
MethodDescriptor method = Iterables.getOnlyElement(methods);
if (method.getAnnotation().structField()) {
result = FuncallExpression.callMethod(
method, name, objValue, new Object[] {}, loc);
}
}
} catch (ExecutionException | IllegalAccessException | InvocationTargetException e) {
throw new EvalException(loc, "Method invocation failed: " + e);
}
}
return result;
}
@Override
public void accept(SyntaxTreeVisitor visitor) {
visitor.visit(this);
}
@Override
SkylarkType validate(ValidationEnvironment env) throws EvalException {
obj.validate(env);
// TODO(bazel-team): check existance of field
return SkylarkType.UNKNOWN;
}
}
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