/*
* Copyright 2009 Google Inc.
*
* 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.common.css.compiler.ast;
import java.util.List;
/**
* Encapsulates a custom function callable from GSS stylesheet files.
*
*/
public interface GssFunction {
/**
* Returns the number of parsed arguments that this function takes,
* or {@code null} if the number of arguments may vary.
*/
Integer getNumExpectedArguments();
/**
* Processes a list of function call arguments and returns a list of
* CssNodes representing this call's output, which replace the input
* nodes in the AST. Errors will be reported to the ErrorManager.
*/
List<CssValueNode> getCallResultNodes(
List<CssValueNode> args, ErrorManager errorManager)
throws GssFunctionException;
/**
* Processes a list of strings as function arguments and returns a string
* result. Errors are reported by throwing {@link GssFunctionException}.
*/
String getCallResultString(List<String> args) throws GssFunctionException;
}