ElementsUtil.java

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// -*- Mode: java; c-basic-offset: 2; -*-
// Copyright 2009-2011 Google, All Rights reserved
// Copyright 2011-2014 MIT, All rights reserved
// Released under the Apache License, Version 2.0
// http://www.apache.org/licenses/LICENSE-2.0
 
package com.google.appinventor.components.runtime.util;
 
import com.google.appinventor.components.runtime.errors.YailRuntimeError;
 
public class ElementsUtil {
 
  public static YailList elementsFromString(String itemString){
    YailList items = new YailList();
    if (itemString.length() > 0) {
      items = YailList.makeList((Object[]) itemString.split(" *, *"));
    }
 
    return items;
  }
 
  public static YailList elements(YailList itemList, String componentName){
    Object[] objects = itemList.toStringArray();
    for (int i = 0; i < objects.length; i++) {
      if (!(objects[i] instanceof String)) {
        throw new YailRuntimeError("Items passed to " + componentName + " must be Strings",
            "Error");
      }
    }
    // this is not changing itemlist.  it's just checking that the items are strings
    return itemList;
  }
 
  public static int selectionIndex(int index, YailList items){
    if (index <= 0 || index > items.size()) {
      return 0;
    } else {
      return index;
    }
  }
 
  public static String setSelectionFromIndex(int index, YailList items){
    if (index == 0)
      return "";
    // YailLists are 0-based, but we want to be 1-based.
    return items.getString(index - 1);
  }
 
  public static int setSelectedIndexFromValue(String value, YailList items){
    // Now, we need to change SelectionIndex to correspond to Selection.
    // If multiple Selections have the same SelectionIndex, use the first.
    // If none do, arbitrarily set the SelectionIndex to its default value
    // of 0.
    for (int i = 0; i < items.size(); i++) {
      // The comparison is case-sensitive to be consistent with yail-equal?.
      if (items.getString(i).equals(value)) {
        return i + 1;
      }
    }
    return 0;
  }
 
}