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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.base.Preconditions;
import java.util.List;
import javax.annotation.Nullable;
/**
* Syntax node for a function argument.
*
* <p>Argument is a base class for arguments passed in a call (@see Argument.Passed)
* or defined as part of a function definition (@see Parameter).
* It is notably used by some {@link Parser} and printer functions.
*/
public abstract class Argument extends ASTNode {
public boolean isStar() {
return false;
}
public boolean isStarStar() {
return false;
}
/**
* Argument.Passed is the class of arguments passed in a function call
* (as opposed to being used in a definition -- @see Parameter for that).
* Argument.Passed is usually what we mean when informally say "argument".
*
* <p>An Argument.Passed can be Positional, Keyword, Star, or StarStar.
*/
public abstract static class Passed extends Argument {
/** the value to be passed by this argument */
protected final Expression value;
private Passed(Expression value) {
this.value = Preconditions.checkNotNull(value);
}
public boolean isPositional() {
return false;
}
public boolean isKeyword() {
return false;
}
@Nullable public String getName() { // only for keyword arguments
return null;
}
public Expression getValue() {
return value;
}
@Override
public void accept(SyntaxTreeVisitor visitor) {
visitor.visit(this);
}
}
/** positional argument: Expression */
public static class Positional extends Passed {
public Positional(Expression value) {
super(value);
}
@Override public boolean isPositional() {
return true;
}
@Override
public String toString() {
return String.valueOf(value);
}
}
/** keyword argument: K = Expression */
public static class Keyword extends Passed {
final String name;
public Keyword(String name, Expression value) {
super(value);
this.name = name;
}
@Override public String getName() {
return name;
}
@Override public boolean isKeyword() {
return true;
}
@Override
public String toString() {
return name + " = " + value;
}
}
/** positional rest (starred) argument: *Expression */
public static class Star extends Passed {
public Star(Expression value) {
super(value);
}
@Override public boolean isStar() {
return true;
}
@Override
public String toString() {
return "*" + value;
}
}
/** keyword rest (star_starred) parameter: **Expression */
public static class StarStar extends Passed {
public StarStar(Expression value) {
super(value);
}
@Override public boolean isStarStar() {
return true;
}
@Override
public String toString() {
return "**" + value;
}
}
/** Some arguments failed to satisfy python call convention strictures */
protected static class ArgumentException extends Exception {
/** construct an ArgumentException from a message only */
public ArgumentException(String message) {
super(message);
}
}
/**
* Validate that the list of Argument's, whether gathered by the Parser or from annotations,
* satisfies the requirements of the Python calling conventions: all Positional's first,
* at most one Star, at most one StarStar, at the end only.
*/
public static void validateFuncallArguments(List<Passed> arguments)
throws ArgumentException {
boolean hasNamed = false;
boolean hasStar = false;
boolean hasKwArg = false;
for (Passed arg : arguments) {
if (hasKwArg) {
throw new ArgumentException("argument after **kwargs");
}
if (arg.isPositional()) {
if (hasNamed) {
throw new ArgumentException("non-keyword arg after keyword arg");
} else if (arg.isStar()) {
throw new ArgumentException("only named arguments may follow *expression");
}
} else if (arg.isKeyword()) {
hasNamed = true;
} else if (arg.isStar()) {
if (hasStar) {
throw new ArgumentException("more than one *stararg");
}
hasStar = true;
} else {
hasKwArg = true;
}
}
}
}
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