Create_NFAConcatenation
(NFA_GRAPH graphOne,
NFA_GRAPH graphTwo)
{
NFA_GRAPH newGraph = null;
if (graphOne == null && graphTwo != null)
{
newGraph = graphTwo;
}
else if (graphOne != null && graphTwo == null)
{
newGraph = graphOne;
}
else if (graphOne != null && graphTwo != null)
{
graphOne.endNode.nodeType = NODE_TYPE.TRANSITIONING;
graphTwo.startNode.nodeType = NODE_TYPE.TRANSITIONING;
EDGE newEdge = new EDGE(CONSTANTS.EMPTY_SYMBOL, graphTwo.startNode);
graphOne.endNode.edges.Add(newEdge);
graphOne.endNode = graphTwo.endNode;
newGraph = graphOne;
}
return(newGraph);
}
Process_GroupingSymbol
(int regExp_itr,
int EndOfRegEx_itr,
NFA_GRAPH nfaGraph)
{
NFA_GRAPH newGraph = null;
int startSubRE = regExp_itr + 1;
int endSubRE = Get_IndexOfGroupClosingSybol(regExp_itr + 1, EndOfRegEx_itr);
if (endSubRE != 0)
{
regExp_itr = endSubRE;
newGraph = Get_NFAFromRE(startSubRE, endSubRE, null);
newGraph = Process_KleeneClosureSymbol(ref regExp_itr, EndOfRegEx_itr, newGraph);
newGraph = Create_NFAConcatenation(nfaGraph, newGraph);
newGraph = Get_NFAFromRE(regExp_itr + 1, EndOfRegEx_itr, newGraph);
}
else
{
newGraph = null;
}
return(newGraph);
}
Process_UnionSymbol
(int regExp_itr,
int EndOfRegEx_itr,
NFA_GRAPH nfaGraph)
{
return(Create_NFAUnion(nfaGraph, Get_NFAFromRE(regExp_itr + 1, EndOfRegEx_itr, null)));
}
public static NFA_GRAPH Create_NFAKleeneClosure(NFA_GRAPH nfaGraph)
{
NFA_GRAPH newGraph = null;
if (nfaGraph != null)
{
nfaGraph.startNode.nodeType = NODE_TYPE.TRANSITIONING;
nfaGraph.endNode.nodeType = NODE_TYPE.TRANSITIONING;
NODE startNode = NODE.CreateNode(NODE_TYPE.START);
NODE endNode = NODE.CreateNode(NODE_TYPE.END);
EDGE endEdge = new EDGE(CONSTANTS.EMPTY_SYMBOL, endNode);
nfaGraph.endNode.edges.Add(endEdge);
EDGE endToStartEdge = new EDGE(CONSTANTS.EMPTY_SYMBOL, nfaGraph.startNode);
nfaGraph.endNode.edges.Add(endToStartEdge);
EDGE newStartToStartEdge = new EDGE(CONSTANTS.EMPTY_SYMBOL, nfaGraph.startNode);
startNode.edges.Add(newStartToStartEdge);
EDGE newStartToNewEndEdge = new EDGE(CONSTANTS.EMPTY_SYMBOL, endNode);
startNode.edges.Add(newStartToNewEndEdge);
newGraph = new NFA_GRAPH(startNode, endNode);
}
return(newGraph);
}
public void Get_NFAFromRE_Test()
{
//Arrange
NFA_GRAPH nfaGraph = new NFA_GRAPH("AB");
//Act
//Assert
Assert.IsTrue(true);
}
Create_NFAOneChar
(char character)
{
NODE startNode = NODE.CreateNode(NODE_TYPE.START);
NODE endNode = NODE.CreateNode(NODE_TYPE.END);
EDGE edge = new EDGE(character, endNode);
startNode.edges.Add(edge);
NFA_GRAPH newGraph = new NFA_GRAPH(startNode, endNode);
return(newGraph);
}
Process_SkippingSymbol
(int regExp_itr,
int EndOfRegEx_itr,
NFA_GRAPH nfaGraph)
{
NFA_GRAPH newGraph = null;
if (regExp_itr + 1 < EndOfRegEx_itr)
{
newGraph = Process_ConcatenationSymbol(regExp_itr + 1, EndOfRegEx_itr, null);
}
return(newGraph);
}
Process_ConcatenationSymbol
(int regExp_itr,
int EndOfRegEx_itr,
NFA_GRAPH nfaGraph)
{
NFA_GRAPH newGraph = null;
newGraph = Create_NFAOneChar(regExp[regExp_itr]);
newGraph = Process_KleeneClosureSymbol(ref regExp_itr, EndOfRegEx_itr, newGraph);
newGraph = Create_NFAConcatenation(nfaGraph, newGraph);
newGraph = Get_NFAFromRE(regExp_itr + 1, EndOfRegEx_itr, newGraph);
return(newGraph);
}
Process_SequencingSymbol
(int regExp_itr,
int EndOfRegEx_itr,
NFA_GRAPH nfaGraph)
{
NFA_GRAPH newGraph = null;
char sequenceIterator = (char)0;
int startSubRE = regExp_itr + 1;
int endSubRE = Get_IndexOfSequenceClosingSybol(regExp_itr + 1, EndOfRegEx_itr);
if (endSubRE != 0)
{
regExp_itr = endSubRE;
if (regExp[endSubRE - 1] > regExp[startSubRE])
{
while ((regExp[startSubRE] + sequenceIterator) <= regExp[(endSubRE - 1)])
{
newGraph = Create_NFAUnion(Create_NFAOneChar((char)(regExp[startSubRE] + sequenceIterator)), newGraph);
sequenceIterator++;
}
newGraph = Process_KleeneClosureSymbol(ref regExp_itr, EndOfRegEx_itr, newGraph);
newGraph = Create_NFAConcatenation(nfaGraph, newGraph);
newGraph = Get_NFAFromRE(regExp_itr + 1, EndOfRegEx_itr, newGraph);
}
else
{
newGraph = null;
//TODO: Log an Error
}
}
else
{
newGraph = null;
//TODO: Log an Error
}
return(newGraph);
}
Process_KleeneClosureSymbol
(ref int regExp_itr,
int EndOfRegEx_itr,
NFA_GRAPH nfaGraph)
{
NFA_GRAPH newGraph = nfaGraph;
if (regExp_itr + 1 != EndOfRegEx_itr)
{
if (regExp[(regExp_itr + 1)].ToString() == CONSTANTS.KLEENE_STAR_SYMBOL)
{
newGraph = Create_NFAKleeneClosure(nfaGraph);
regExp_itr++;
}
}
return(newGraph);
}
public static NFA_GRAPH Create_NFAUnion(NFA_GRAPH graphOne, NFA_GRAPH graphTwo)
{
NFA_GRAPH newGraph = null;
if (graphOne == null && graphTwo != null)
{
newGraph = graphTwo;
}
else if (graphOne != null && graphTwo == null)
{
newGraph = graphOne;
}
else if (graphOne != null && graphTwo != null)
{
NODE startNode = NODE.CreateNode(NODE_TYPE.START);
NODE endNode = NODE.CreateNode(NODE_TYPE.END);
graphOne.startNode.nodeType = NODE_TYPE.TRANSITIONING;
graphTwo.startNode.nodeType = NODE_TYPE.TRANSITIONING;
graphOne.endNode.nodeType = NODE_TYPE.TRANSITIONING;
graphTwo.endNode.nodeType = NODE_TYPE.TRANSITIONING;
EDGE startOneEdge = new EDGE(CONSTANTS.EMPTY_SYMBOL, graphOne.startNode);
EDGE startTwoEdge = new EDGE(CONSTANTS.EMPTY_SYMBOL, graphTwo.startNode);
startNode.edges.Add(startOneEdge);
startNode.edges.Add(startTwoEdge);
EDGE endOneEdge = new EDGE(CONSTANTS.EMPTY_SYMBOL, endNode);
EDGE endTwoEdge = new EDGE(CONSTANTS.EMPTY_SYMBOL, endNode);
graphOne.endNode.edges.Add(endOneEdge);
graphTwo.endNode.edges.Add(endTwoEdge);
newGraph = new NFA_GRAPH(startNode, endNode);
}
return(newGraph);
}
private NFA_GRAPH Get_NFAFromRE
(int regExp_itr,
int EndOfRegEx_itr,
NFA_GRAPH nfaGraph)
{
NFA_GRAPH new_NFAGraph = null;
if (regExp_itr != EndOfRegEx_itr)
{
switch (regExp[regExp_itr].ToString())
{
case CONSTANTS.UNION_SYMBOL:
new_NFAGraph = Process_UnionSymbol(regExp_itr, EndOfRegEx_itr, nfaGraph);
break;
case CONSTANTS.OPEN_GROUPING_SYMBOL:
new_NFAGraph = Process_GroupingSymbol(regExp_itr, EndOfRegEx_itr, nfaGraph);
break;
case CONSTANTS.CLOSE_GROUPING_SYMBOL:
new_NFAGraph = null;
//ToDo: Log an Error
break;
case CONSTANTS.SKIPPING_SYMBOL:
new_NFAGraph = Process_SkippingSymbol(regExp_itr, EndOfRegEx_itr, nfaGraph);
break;
case CONSTANTS.KLEENE_STAR_SYMBOL:
new_NFAGraph = null;
regExp_itr++;
//ToDo: Log an Error
break;
case CONSTANTS.OPEN_SEQUENCING_SYMBOL:
new_NFAGraph = Process_SequencingSymbol(regExp_itr, EndOfRegEx_itr, nfaGraph);
break;
default:
new_NFAGraph = Process_ConcatenationSymbol(regExp_itr, EndOfRegEx_itr, nfaGraph);
break;
}
}
if (new_NFAGraph == null)
{
new_NFAGraph = nfaGraph;
}
return(new_NFAGraph);
}
