/// <summary>
/// Create intersections of <paramref name="leftPattern"/> and <paramref name="rightPattern"/>.
/// </summary>
/// <param name="leftPattern"></param>
/// <param name="rightPattern"></param>
/// <returns>intersections</returns>
public static IEnumerable <String> Intersections(string leftPattern, string rightPattern)
{
// Read in the tokens
StructList24 <Token> leftTokens = new StructList24 <Token>(), rightTokens = new StructList24 <Token>();
Token.Enumerator leftEnumerator = new Token.Enumerator(leftPattern), rightEnumerator = new Token.Enumerator(rightPattern);
while (leftEnumerator.MoveNext())
{
leftTokens.Add(leftEnumerator.Current);
}
while (rightEnumerator.MoveNext())
{
rightTokens.Add(rightEnumerator.Current);
}
// Queue of scenarios as index pairs and result so far.
List <Line> queue = new List <Line>();
// List of already yielded strings
HashSet <Line> visited = new HashSet <Line>();
// Queue the starting position
Queue(queue, visited, 0, 0, null);
// Process queue
while (queue.Count > 0)
{
// Take indices from queue
Line line = queue[queue.Count - 1];
int li = line.li, ri = line.ri; List <Token> result = line.tokens;
queue.RemoveAt(queue.Count - 1);
// Has more tokens
bool leftHasMore = li < leftTokens.Count, rightHasMore = ri < rightTokens.Count;
// End of tokens on both streams
if (!leftHasMore && !rightHasMore)
{
// Print to string
string pattern = Print(result);
// yield result
yield return(pattern);
}
// left still has tokens, right is at end
else if (leftHasMore && !rightHasMore)
{
// Take token
Token l = leftTokens[li];
// "*" and "**" matches against ""
if (l == Token.Type.Star || l == Token.Type.StarStar)
{
Queue(queue, visited, li + 1, ri, result);
}
}
// left is at end, right still has tokens
else if (!leftHasMore && rightHasMore)
{
// Take token and type
Token r = rightTokens[ri];
// "" matches against "*" and "**"
if (r == Token.Type.Star || r == Token.Type.StarStar)
{
Queue(queue, visited, li, ri + 1, result);
}
}
// left and right have tokens
if (leftHasMore && rightHasMore)
{
// Take tokens
Token l = leftTokens[li], r = rightTokens[ri];
// l == **
if (l == Token.Type.StarStar)
{
// Match one and more later
CloneAndAppend(queue, visited, li, ri + 1, result, r);
// r = *, r = **
if (r == Token.Type.Star || r == Token.Type.StarStar)
{
//
Append(queue, visited, li + 1, ri, result, r);
}
else
// r = x
{
// Match to nothing
Queue(queue, visited, li + 1, ri, result);
}
// Next scenario
continue;
}
// r == **
if (r == Token.Type.StarStar)
{
// Match one and more later
CloneAndAppend(queue, visited, li + 1, ri, result, l);
// l = *, l = **
if (l == Token.Type.Star || l == Token.Type.StarStar)
{
//
Append(queue, visited, li, ri + 1, result, l);
}
else
{
// Match to nothing
Queue(queue, visited, li, ri + 1, result);
}
// Next scenario
continue;
}
// l == *
if (l == Token.Type.Star)
{
// * & /
if (r == Token.Type.Slash)
{
// Match / to nothing
Queue(queue, visited, li + 1, ri, result);
continue;
}
// Match to one and more later
CloneAndAppend(queue, visited, li, ri + 1, result, r);
// Match to r = *
if (r == Token.Type.Star)
{
Append(queue, visited, li + 1, ri, result, r);
}
else
{
// Match to nothing
Queue(queue, visited, li + 1, ri, result);
}
// Next scenario
continue;
}
// r == *
if (r == Token.Type.Star)
{
// / & *
if (l == Token.Type.Slash)
{
// Match / to nothing
Queue(queue, visited, li, ri + 1, result);
continue;
}
// Match one, and more later
CloneAndAppend(queue, visited, li + 1, ri, result, l);
if (l == Token.Type.Star)
{
Append(queue, visited, li, ri + 1, result, l);
}
else
{
// Match to nothing
Queue(queue, visited, li, ri + 1, result);
}
// Next scenario
continue;
}
// l == ?
if (l == Token.Type.QuestionMark)
{
// ? & /
if (r == Token.Type.Slash)
{
continue;
}
// Downgrade '*' and '**' to '?'
if (r.Kind == Token.Type.Star || r.Kind == Token.Type.StarStar)
{
r = Token.Type.QuestionMark;
}
// Append what ever is in right token
Append(queue, visited, li + 1, ri + 1, result, r);
// Next scenario
continue;
}
// r == ?
if (r == Token.Type.QuestionMark)
{
// / & ?
if (l == Token.Type.Slash)
{
continue;
}
// Downgrade '*' and '**' to '?'
if (l.Kind == Token.Type.Star || l.Kind == Token.Type.StarStar)
{
l = Token.Type.QuestionMark;
}
// Append what ever is in left token
Append(queue, visited, li + 1, ri + 1, result, l);
// Next scenario
continue;
}
// l == r
if (l == r)
{
// Append, move indices and queue.
Append(queue, visited, li + 1, ri + 1, result, l);
// Next scenario
continue;
}
}
}
//Console.Write($" (visited={visited.Count}) ");
}
/// <summary>
/// Create union of <paramref name="leftPattern"/> and <paramref name="rightPattern"/>.
/// </summary>
/// <param name="leftPattern"></param>
/// <param name="rightPattern"></param>
/// <returns>union that contains <paramref name="leftPattern"/> and <paramref name="rightPattern"/>. May return broader union that minimal due to lack of expression capability to hold in a single pattern string.</returns>
public static string Union(string leftPattern, string rightPattern)
{
// Same pattern
if (leftPattern == rightPattern)
{
return(leftPattern);
}
// Read in the tokens
StructList24 <Token> leftTokens = new StructList24 <Token>(), rightTokens = new StructList24 <Token>();
Token.Enumerator leftEnumerator = new Token.Enumerator(leftPattern), rightEnumerator = new Token.Enumerator(rightPattern);
while (leftEnumerator.MoveNext())
{
leftTokens.Add(leftEnumerator.Current);
}
while (rightEnumerator.MoveNext())
{
rightTokens.Add(rightEnumerator.Current);
}
// Queue of scenarios as index pairs and result so far.
List <Line> queue = new List <Line>();
// List of already yielded strings
HashSet <Line> visited = new HashSet <Line>();
// Queue the starting position
Queue(queue, visited, 0, 0, null);
// Final result
List <Token> finalresult = null; int finalscore = int.MinValue;
// Process queue
while (queue.Count > 0)
{
// Take indices from queue
Line line = queue[queue.Count - 1];
int li = line.li, ri = line.ri; List <Token> result = line.tokens;
queue.RemoveAt(queue.Count - 1);
// Has more tokens
bool leftHasMore = li < leftTokens.Count, rightHasMore = ri < rightTokens.Count;
// l = Left input, r = right input, _ = last in result
Token l = leftHasMore ? leftTokens[li] : (Token)Token.Type.None, r = rightHasMore ? rightTokens[ri] : (Token)Token.Type.None, _ = result == null || result.Count == 0 ? (Token)Token.Type.None : result[result.Count - 1];
// End of tokens on both streams
if (!leftHasMore && !rightHasMore)
{
int score = Score(result);
if (score > finalscore)
{
finalresult = result; finalscore = score;
}
continue;
}
// left or right have tokens
if (leftHasMore || rightHasMore)
{
// l == **
if (l == Token.Type.StarStar)
{
if (_ == Token.Type.StarStar)
{
Queue(queue, visited, li + 1, ri, result);
}
else
{
Append(queue, visited, li + 1, ri, result, l);
}
continue;
}
// r == **
if (r == Token.Type.StarStar)
{
if (_ == Token.Type.StarStar)
{
Queue(queue, visited, li, ri + 1, result);
}
else
{
Append(queue, visited, li, ri + 1, result, r);
}
continue;
}
// l == *
if (l == Token.Type.Star)
{
if (_ == Token.Type.Star || _ == Token.Type.StarStar)
{
Queue(queue, visited, li + 1, ri, result);
}
else
{
Append(queue, visited, li + 1, ri, result, l);
}
continue;
}
// r == *
if (r == Token.Type.Star)
{
if (_ == Token.Type.Star || _ == Token.Type.StarStar)
{
Queue(queue, visited, li, ri + 1, result);
}
else
{
Append(queue, visited, li, ri + 1, result, r);
}
continue;
}
// l == r
if (l == r)
{
Append(queue, visited, li + 1, ri + 1, result, l);
continue;
}
// l == ? && r == c
if (l == Token.Type.QuestionMark && r.Kind == Token.Type.Char)
{
Append(queue, visited, li + 1, ri + 1, result, l);
continue;
}
// l == c && r == ?
if (l.Kind == Token.Type.Char && r == Token.Type.QuestionMark)
{
Append(queue, visited, li + 1, ri + 1, result, l);
continue;
}
// l == c || r == c
if (l.Kind == Token.Type.Char || r.Kind == Token.Type.Char)
{
// Add ?
if (l.Kind == Token.Type.Char && r.Kind == Token.Type.Char)
{
CloneAndAppend(queue, visited, li + 1, ri + 1, result, Token.Type.QuestionMark);
}
// Add *
if (_ != Token.Type.Star && _ != Token.Type.StarStar)
{
if (l.Kind == Token.Type.Char)
{
CloneAndAppend(queue, visited, li + 1, ri, result, Token.Type.Star);
}
if (r.Kind == Token.Type.Char)
{
Append(queue, visited, li, ri + 1, result, Token.Type.Star);
}
}
else
// Use previous *
{
if (l.Kind == Token.Type.Char)
{
CloneAndAppend(queue, visited, li + 1, ri, result, Token.Type.None);
}
if (r.Kind == Token.Type.Char)
{
Queue(queue, visited, li, ri + 1, result);
}
}
continue;
}
{
// Replace * with **
if (_ == Token.Type.Star)
{
result[result.Count - 1] = Token.Type.StarStar;
if (l != Token.Type.None)
{
CloneAndAppend(queue, visited, li + 1, ri, result, Token.Type.None);
}
if (r != Token.Type.None)
{
Queue(queue, visited, li, ri + 1, result);
}
}
// Add **
else if (_ != Token.Type.StarStar)
{
if (l != Token.Type.None)
{
CloneAndAppend(queue, visited, li + 1, ri, result, Token.Type.StarStar);
}
if (r != Token.Type.None)
{
Append(queue, visited, li, ri + 1, result, Token.Type.StarStar);
}
}
else
// Use previous **
{
if (l != Token.Type.None)
{
CloneAndAppend(queue, visited, li + 1, ri, result, Token.Type.None);
}
if (r != Token.Type.None)
{
Queue(queue, visited, li, ri + 1, result);
}
}
}
}
}
//Console.Write($" (visited={visited.Count}) ");
return(Print(finalresult));
// Heuristic score
int Score(List <Token> result)
{
if (result == null)
{
return(int.MinValue);
}
int x = 0;
foreach (Token t in result)
{
if (t.Kind == Token.Type.Char)
{
x += 256;
}
else if (t.Kind == Token.Type.QuestionMark)
{
x += 16;
}
else if (t.Kind == Token.Type.Slash)
{
x += 1024;
}
else if (t.Kind == Token.Type.Star)
{
x -= 4;
}
else if (t.Kind == Token.Type.StarStar)
{
x -= 16;
}
}
return(x);
}
}
