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// 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.ImmutableList;
import com.google.devtools.build.lib.cmdline.Label;
import com.google.devtools.build.lib.events.Location;
import com.google.devtools.build.lib.profiler.Profiler;
import com.google.devtools.build.lib.profiler.ProfilerTask;
import com.google.devtools.build.lib.profiler.SilentCloseable;
import com.google.devtools.build.lib.skylarkinterface.SkylarkPrinter;
import com.google.devtools.build.lib.syntax.Environment.LexicalFrame;
/**
* The actual function registered in the environment. This function is defined in the parsed code
* using {@link FunctionDefStatement}.
*/
public class UserDefinedFunction extends BaseFunction {
private final ImmutableList<Statement> statements;
// we close over the globals at the time of definition
private final Environment.GlobalFrame definitionGlobals;
public UserDefinedFunction(
String name,
Location location,
FunctionSignature.WithValues<Object, SkylarkType> signature,
ImmutableList<Statement> statements,
Environment.GlobalFrame definitionGlobals) {
super(name, signature, location);
this.statements = statements;
this.definitionGlobals = definitionGlobals;
}
public ImmutableList<Statement> getStatements() {
return statements;
}
public Environment.GlobalFrame getDefinitionGlobals() {
return definitionGlobals;
}
@Override
public Object call(Object[] arguments, FuncallExpression ast, Environment env)
throws EvalException, InterruptedException {
if (env.mutability().isFrozen()) {
throw new EvalException(getLocation(), "Trying to call in frozen environment");
}
if (env.isRecursiveCall(this)) {
throw new EvalException(getLocation(),
String.format("Recursion was detected when calling '%s' from '%s'",
getName(), env.getCurrentFunction().getName()));
}
ImmutableList<String> names = signature.getSignature().getNames();
LexicalFrame lexicalFrame =
LexicalFrame.createForUserDefinedFunctionCall(env.mutability(), /*numArgs=*/ names.size());
try (SilentCloseable c = Profiler.instance().profile(ProfilerTask.SKYLARK_USER_FN, getName())) {
env.enterScope(this, lexicalFrame, ast, definitionGlobals);
// Registering the functions's arguments as variables in the local Environment
// foreach loop is not used to avoid iterator overhead
for (int i = 0; i < names.size(); ++i) {
env.update(names.get(i), arguments[i]);
}
Eval eval = Eval.fromEnvironment(env);
try {
for (Statement stmt : statements) {
if (stmt instanceof ReturnStatement) {
// Performance optimization.
// Executing the statement would throw an exception, which is slow.
Expression returnExpr = ((ReturnStatement) stmt).getReturnExpression();
if (returnExpr == null) {
return Runtime.NONE;
}
return returnExpr.eval(env);
} else {
eval.exec(stmt);
}
}
} catch (ReturnStatement.ReturnException e) {
return e.getValue();
}
return Runtime.NONE;
} finally {
env.exitScope();
}
}
@Override
public void repr(SkylarkPrinter printer) {
Label label = this.definitionGlobals.getTransitiveLabel();
printer.append("<function " + getName());
if (label != null) {
printer.append(" from " + label);
}
printer.append(">");
}
}
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