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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.devtools.build.lib.skyframe.serialization.autocodec.AutoCodec;
import java.io.IOException;
import javax.annotation.Nullable;
/**
* Syntax node for a Parameter in a function (or lambda) definition; it's a subclass of Argument,
* and contrasts with the class Argument.Passed of arguments in a function call.
*
* <p>There are four concrete subclasses of Parameter: Mandatory, Optional, Star, StarStar.
*
* <p>See FunctionSignature for how a valid list of Parameter's is organized as a signature, e.g.
* def foo(mandatory, optional = e1, *args, mandatorynamedonly, optionalnamedonly = e2, **kw): ...
*
* <p>V is the class of a defaultValue (Expression at compile-time, Object at runtime),
* T is the class of a type (Expression at compile-time, SkylarkType at runtime).
*/
public abstract class Parameter<V, T> extends Argument {
@Nullable protected final Identifier identifier;
@Nullable protected final T type;
private Parameter(@Nullable Identifier identifier, @Nullable T type) {
this.identifier = identifier;
this.type = type;
}
public boolean isMandatory() {
return false;
}
public boolean isOptional() {
return false;
}
@Override
public boolean isStar() {
return false;
}
@Override
public boolean isStarStar() {
return false;
}
@Nullable
public String getName() {
return identifier != null ? identifier.getName() : null;
}
@Nullable
public Identifier getIdentifier() {
return identifier;
}
public boolean hasName() {
return true;
}
@Nullable
public T getType() {
return type;
}
@Nullable
public V getDefaultValue() {
return null;
}
/** mandatory parameter (positional or key-only depending on position): Ident */
@AutoCodec
public static final class Mandatory<V, T> extends Parameter<V, T> {
public Mandatory(Identifier identifier) {
this(identifier, null);
}
@AutoCodec.Instantiator
public Mandatory(Identifier identifier, @Nullable T type) {
super(identifier, type);
}
@Override
public boolean isMandatory() {
return true;
}
@Override
public void prettyPrint(Appendable buffer) throws IOException {
buffer.append(getName());
}
}
/** optional parameter (positional or key-only depending on position): Ident = Value */
@AutoCodec
public static final class Optional<V, T> extends Parameter<V, T> {
public final V defaultValue;
public Optional(Identifier identifier, @Nullable V defaultValue) {
this(identifier, null, defaultValue);
}
@AutoCodec.Instantiator
public Optional(Identifier identifier, @Nullable T type, @Nullable V defaultValue) {
super(identifier, type);
this.defaultValue = defaultValue;
}
@Override
@Nullable
public V getDefaultValue() {
return defaultValue;
}
@Override
public boolean isOptional() {
return true;
}
@Override
public void prettyPrint(Appendable buffer) throws IOException {
buffer.append(getName());
buffer.append('=');
// This should only ever be used on a parameter representing static information, i.e. with V
// and T instantiated as Expression.
((Expression) defaultValue).prettyPrint(buffer);
}
// Keep this as a separate method so that it can be used regardless of what V and T are
// parameterized with.
@Override
public String toString() {
return getName() + "=" + defaultValue;
}
}
/** extra positionals parameter (star): *identifier */
@AutoCodec
public static final class Star<V, T> extends Parameter<V, T> {
@AutoCodec.Instantiator
public Star(@Nullable Identifier identifier, @Nullable T type) {
super(identifier, type);
}
public Star(@Nullable Identifier identifier) {
this(identifier, null);
}
@Override
public boolean hasName() {
return getName() != null;
}
@Override
public boolean isStar() {
return true;
}
@Override
public void prettyPrint(Appendable buffer) throws IOException {
buffer.append('*');
if (getName() != null) {
buffer.append(getName());
}
}
}
/** extra keywords parameter (star_star): **identifier */
@AutoCodec
public static final class StarStar<V, T> extends Parameter<V, T> {
@AutoCodec.Instantiator
public StarStar(Identifier identifier, @Nullable T type) {
super(identifier, type);
}
public StarStar(Identifier identifier) {
this(identifier, null);
}
@Override
public boolean isStarStar() {
return true;
}
@Override
public void prettyPrint(Appendable buffer) throws IOException {
buffer.append("**");
buffer.append(getName());
}
}
@Override
@SuppressWarnings("unchecked")
public void accept(SyntaxTreeVisitor visitor) {
visitor.visit((Parameter<Expression, Expression>) this);
}
}
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