diff options
Diffstat (limited to 'Anoto/StateMachine.cs')
| -rw-r--r-- | Anoto/StateMachine.cs | 151 |
1 files changed, 151 insertions, 0 deletions
diff --git a/Anoto/StateMachine.cs b/Anoto/StateMachine.cs new file mode 100644 index 0000000..488376d --- /dev/null +++ b/Anoto/StateMachine.cs @@ -0,0 +1,151 @@ +using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Text;
+using System.Diagnostics;
+using System.Xml;
+
+namespace Anoto
+{
+
+ /// <remarks>
+ /// This class implements a table-driven finite state machine.
+ /// The table is defined by an XML document. The System.Xml.XmlTextReader
+ /// class is used for fast scanning of the table and allows larger tables
+ /// to be used as opposed to System.Xml.XmlDocument.
+ /// </remarks>
+ class XMLStateMachine
+ {
+
+ private XmlTextReader tableParser;
+ private string stateCurrent;
+ private string stateTable;
+ private string action;
+
+ public XMLStateMachine()
+ {
+ tableParser = null;
+ stateCurrent = String.Empty;
+ stateTable = String.Empty;
+ action = String.Empty;
+ }
+
+ /// <summary>
+ /// The CurrentState property contains the current state in the table.
+ /// </summary>
+ public string CurrentState
+ {
+ get
+ {
+ return stateCurrent;
+ }
+ set
+ {
+ stateCurrent = value;
+ }
+ }
+
+ /// <summary>
+ /// The Action property contains a user-defined string
+ /// that indicates an action to be performed on the current transition.
+ /// </summary>
+ public string Action
+ {
+ get
+ {
+ return action;
+ }
+ }
+
+ /// <summary>
+ /// The StateTable property contains the state table file name.
+ /// </summary>
+ public string StateTable
+ {
+ get
+ {
+ return stateTable;
+ }
+ set
+ {
+ stateTable = value;
+ }
+ }
+
+ /// <summary>
+ /// The Next method gets the next valid state given
+ /// the current state and the supplied input.
+ /// </summary>
+ /// <param name="inputArg">The input used to trigger a state transition.</param>
+ /// <returns>A string that identifies the next state</returns>
+ public string Next(string inputArg)
+ {
+ string nextState = String.Empty;
+
+ if (CurrentState != String.Empty)
+ {
+ try
+ {
+ tableParser = new XmlTextReader(StateTable);
+
+ while (true == tableParser.Read())
+ {
+ if (XmlNodeType.Element == tableParser.NodeType)
+ {
+ if (true == tableParser.HasAttributes)
+ {
+ string state = tableParser.GetAttribute("name");
+ if (state == CurrentState)
+ {
+ // Get transition data
+ while (true == tableParser.Read())
+ {
+ if ((XmlNodeType.Element == tableParser.NodeType) && ("transition" == tableParser.Name))
+ {
+ if (true == tableParser.HasAttributes)
+ {
+ string input = tableParser.GetAttribute("input");
+ if (input == inputArg)
+ {
+ CurrentState = tableParser.GetAttribute("next");
+ nextState = CurrentState;
+ action = tableParser.GetAttribute("action");
+ return nextState;
+ }
+ }
+ }
+ }
+ }
+ }
+ }
+ }
+ }
+ catch (XmlException e)
+ {
+ // Eliminate default trace listener
+ Trace.Listeners.RemoveAt(0);
+ // Add console trace listener
+ TextWriterTraceListener myWriter = new TextWriterTraceListener(System.Console.Out);
+ Trace.Listeners.Add(myWriter);
+ Trace.WriteLine("[XMLStateMachine] Could not load state table definition.");
+ Trace.Indent();
+ Trace.WriteLine(e.Message);
+ Trace.Unindent();
+ // Clean up object
+ tableParser.Close();
+ tableParser = null;
+ stateCurrent = String.Empty;
+ action = String.Empty;
+ }
+ }
+
+ return nextState;
+ }
+
+
+
+
+
+
+ }
+}
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