/Spss/SpssStringVariableValueLabels.cs

using System;

using System.Diagnostics;

using System.Collections;



namespace Spss

{

	/// <summary>

	/// A collection of value labels for a <see cref="SpssStringVariable"/>.

	/// </summary>

	public class SpssStringVariableValueLabelsDictionary : SpssVariableValueLabelsDictionary<string>

	{

		/// <summary>

		/// Creates an instance of the <see cref="SpssStringVariableValueLabelsDictionary"/> class.

		/// </summary>

		public SpssStringVariableValueLabelsDictionary(SpssVariable variable)

			: base(variable, StringComparer.Ordinal)

		{

		}



		#region Attributes

		/// <summary>

		/// The variable hosting this collection.

		/// </summary>

		protected new SpssStringVariable Variable { get { return (SpssStringVariable) base.Variable; } }

	

		/// <summary>

		/// Gets a value indicating whether this string variable can have value labels.

		/// </summary>

		/// <remarks>

		/// SPSS only supports value labels on strings within

		/// <see cref="SpssThinWrapper.SPSS_MAX_SHORTSTRING"/> characters

		/// in length..

		/// </remarks>

		public bool Applies

		{

			get

			{

				return Variable.Length <= SpssSafeWrapper.SPSS_MAX_SHORTSTRING;

			}

		}

		#endregion



		#region Operations

		/// <summary>

		/// Adds a value label.

		/// </summary>

		/// <param name="value">

		/// The response value to associate with the new response label.

		/// </param>

		/// <param name="label">

		/// The new response label.

		/// </param>

		public override void Add(string value, string label)

		{

			if( !Applies ) throw new InvalidOperationException("Cannot add value labels to a long string variable.");

			base.Add(value, label);

		}



		/// <summary>

		/// Updates the SPSS data file with changes made to the collection.

		/// </summary>

		protected internal override void Update()

		{

			foreach( var pair in this )

				SpssSafeWrapper.spssSetVarCValueLabel(FileHandle, Variable.Name, pair.Key, pair.Value);

		}

	

		/// <summary>

		/// Initializes the value labels dictionary from the SPSS data file.

		/// </summary>

		protected override void LoadFromSpssFile() {

			if (!Applies) return;



			string[] values;

			string[] labels;

			ReturnCode result = SpssException.ThrowOnFailure(SpssSafeWrapper.spssGetVarCValueLabels(FileHandle, Variable.Name, out values, out labels), "spssGetVarCValueLabels", ReturnCode.SPSS_NO_LABELS);

			if (result == ReturnCode.SPSS_OK) { // ReturnCode.SPSS_NO_LABELS is nothing special -- just no labels to add

				Debug.Assert(values.Length == labels.Length);

				for (int i = 0; i < values.Length; i++) {

					Add(values[i], labels[i]);

				}

			}

		}



		#endregion

	}

}