Add support for removing fields by index or by item/type

NHapi20/NHapi.Base/Model/AbstractSegment.cs

@@ -21,13 +21,12 @@
 /// this file under either the MPL or the GPL.
 */
 
+using NHapi.Base.Log;
+using NHapi.Base.Parser;
 using System;
 using System.Collections.Generic;
-using System.Linq;
 using System.Reflection;
-using NHapi.Base;
-using NHapi.Base.Parser;
-using NHapi.Base.Log;
+using System.Text.RegularExpressions;
 
 namespace NHapi.Base.Model
 {
@@ -70,7 +69,7 @@ static AbstractSegment()
 		 log = HapiLogFactory.GetHapiLog(typeof(AbstractSegment));
 	  }
 
-		#endregion
+	  #endregion Constructor
 
 	  /// <summary> Returns the Message to which this segment belongs.  </summary>
 	  public virtual IMessage Message
@@ -171,7 +170,6 @@ public virtual IType GetField(int number, int rep)
 				"Can't get repetition " + rep + " from field " + number + " - maximum repetitions is only " +
 				_items[number - 1].MaxRepetitions + " reps.", HL7Exception.APPLICATION_INTERNAL_ERROR);
 
-
 		 //add a rep if necessary ...
 		 if (rep == currentReps)
 		 {
@@ -382,6 +380,72 @@ protected internal virtual void add(Type c, bool required, int maxReps, int leng
 		 _items.Add(new AbstractSegmentItem(c, required, maxReps, length, constructorArgs, description));
 	  }
 
+	  /// <summary>
+	  /// Remove a valid index from a repeatable field.
+	  /// </summary>
+	  /// <param name="fieldNum">Repeatable field number</param>
+	  /// <param name="index">0-based index to be removed</param>
+	  public void RemoveRepetition(int fieldNum, int index)
+	  {
+		 if (fieldNum < 1 || fieldNum > _items.Count)
+		 {
+			throw new HL7Exception($"Can't retrieve field {fieldNum} from segment {GetType().FullName} - there are only {_items[fieldNum - 1].Fields.Count} fields.", HL7Exception.APPLICATION_INTERNAL_ERROR);
+		 }
+
+		 var fields = _items[fieldNum - 1].Fields;
+
+		 if (fields.Count == 0)
+		 {
+			throw new HL7Exception($"Invalid index: {index}, structure {fields.GetType().FullName} has no repetitions");
+		 }
+		 if (fields.Count <= index)
+		 {
+			throw new HL7Exception($"Invalid index: {index}, structure {fields.GetType().FullName} must be between 0 and {fields.Count - 1}");
+		 }
+
+		 fields.RemoveAt(index);
+
+		 return;
+	  }
+
+	  /// <summary>
+	  /// Remove a valid item from a repeatable field.
+	  /// </summary>
+	  /// <param name="fieldNum">Repeatable field number</param>
+	  /// <param name="removeItem">Item to be removed</param>
+	  public void RemoveRepetition(int fieldNum, IType removeItem)
+	  {
+		 if (fieldNum < 1 || fieldNum > _items.Count)
+		 {
+			throw new HL7Exception($"Can't retrieve field {fieldNum} from segment {GetType().FullName} - there are only {_items[fieldNum - 1].Fields.Count} fields.", HL7Exception.APPLICATION_INTERNAL_ERROR);
+		 }
+
+		 var fields = _items[fieldNum - 1].Fields;
+
+		 if (fields.Count == 0)
+		 {
+			throw new HL7Exception($"Structure {fields.GetType().FullName} has no repetitions");
+		 }
+		 if (!fields.Contains(removeItem))
+		 {
+			throw new HL7Exception($"Invalid item specified, structure {fields.GetType().FullName} does not contain {removeItem.ToString()}");
+		 }
+
+		 fields.Remove(removeItem);
+
+		 return;
+	  }
+
+	  /// <summary>
+	  /// Get the 0-based index for an AbstractSegmentItem with a description that matches the given name.
+	  /// </summary>
+	  /// <param name="name">Item name, with all whitespace removed</param>
+	  /// <returns>0-based index, if found.  Otherwise, -1</returns>
+	  public int FindField(string name)
+	  {
+		 return _items.FindIndex(x => Regex.Replace(x.Description, @"\s", "") == name);
+	  }
+
 	  /// <summary> Called from GetField(...) methods.  If a field has been requested that
 	  /// doesn't exist (eg GetField(15) when only 10 fields in segment) adds Varies
 	  /// fields to the end of the segment up to the required number.