user/src/com/google/gwt/resources/gss/ValueFunction.java

/*
 * Copyright 2014 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.gwt.resources.gss;

import com.google.gwt.resources.gss.ast.CssDotPathNode;
import com.google.gwt.thirdparty.common.css.compiler.ast.CssValueNode;
import com.google.gwt.thirdparty.common.css.compiler.ast.ErrorManager;
import com.google.gwt.thirdparty.common.css.compiler.ast.GssFunction;
import com.google.gwt.thirdparty.common.css.compiler.ast.GssFunctionException;
import com.google.gwt.thirdparty.guava.common.collect.ImmutableList;

import java.util.List;

/**
 * Handles the value() function. This function takes a sequence of dot-separated identifiers
 * interpreted as zero-arg method invocations. It can takes a optional prefix and suffix.
 */
public class ValueFunction implements GssFunction {
  public static String getName() {
    return "value";
  }

  @Override
  public List<CssValueNode> getCallResultNodes(List<CssValueNode> args, ErrorManager errorManager)
      throws GssFunctionException {
    if (args.size() == 0 || args.size() > 3) {
      throw new GssFunctionException(getName() + " function takes one, two or three arguments");
    }

    String functionPath = args.get(0).getValue();
    String prefix = null;
    String suffix = null;

    if (args.size() > 1) {
      suffix = args.get(1).getValue();
    }

    if (args.size() > 2) {
      prefix = args.get(2).getValue();
    }

    CssDotPathNode cssDotPathNode = new CssDotPathNode(functionPath, prefix, suffix,
        args.get(0).getSourceCodeLocation());

    return ImmutableList.of((CssValueNode) cssDotPathNode);
  }

  @Override
  public String getCallResultString(List<String> args) throws GssFunctionException {

    String functionPath = args.get(0);
    String prefix = null;
    String suffix = null;

    if (args.size() > 1) {
      suffix = args.get(1);
    }

    if (args.size() > 2) {
      prefix = args.get(2);
    }

    return CssDotPathNode.resolveExpression(null, functionPath, prefix, suffix);
  }

  @Override
  public Integer getNumExpectedArguments() {
    // number of arguments is variable
    return null;
  }
}