Merge pull request #1348 from nemerle/fix_wildcard_pattern_matcher

Implement missing logic in WildPatternMatcher + re-enable unit tests

src/Core/Lib/WildPatternMatcher.cs

@@ -45,66 +45,85 @@ public class WildPatternMatcher
  public IEnumerable<int> FindDcp(string T, string P)
  {
  var sa = new SuffixArray<char>(T.ToCharArray());
+ int textLength = T.Length;
  int[] permitted = new int[T.Length];
- (string[], int[]) pat = SplitPattern(P);
- var l = pat.Item1.Length;
- var Val = new int[l];
- Val[0] = 0;
- for (int i = 1; i < l; ++i)
- {
- Val[i] = Val[i - 1] + pat.Item1[i - 1].Length + pat.Item2[i - 1];
- }
+ (string[] patternParts, int[] dontCares) = SplitPattern(P);
+ var patternLength = patternParts.Length;
+ var Val = CalculateOffsets(patternParts, dontCares);
  var occ_P = new SortedSet<int>();
- for (int i = 0; i < l; ++i)
+ for (int i = 0; i < patternLength; ++i)
  {
- var Pi = pat.Item1[i];
+ var Pi = patternParts[i];
+ var nextPatternWildcards = i<dontCares.Length ? dontCares[i] : 0;
  var occ_Pi = new SortedSet<int>(sa.FindOccurences(Pi.ToCharArray()));
- foreach (var r in occ_Pi)
+ foreach (var pos in occ_Pi)
  {
- ++permitted[r - Val[i]];
- if (permitted[r - Val[i]] == l)
+ int adjustedPos = pos - Val[i];
+ if (!IsValidPos(adjustedPos,Val[i], nextPatternWildcards, textLength))
+ continue;
+ ++permitted[adjustedPos];
+ if (permitted[adjustedPos] == patternLength)
  {
- occ_P.Add(r - Val[i]);
+ occ_P.Add(adjustedPos);
  }
  }
  }
  return occ_P;
  }
+ /// <summary>
+ /// Checks that a match at the position <paramref name="pos" /> and
+ /// length <paramref name="len" /> fits in the text
+ /// </summary>
+ private bool IsValidPos(int pos,int len,int nextPatternWildcards,int textLength)
+ {
+ return pos >= 0 && pos + len + nextPatternWildcards < textLength;
+ }
 
  public IEnumerable<int> FindIdcp(string T, string P)
  {
  var sa = new SuffixArray<char>(T.ToCharArray());
- (string[], int[]) pat = SplitPattern(P);
- var l = pat.Item1.Length;
- var Val = new int[l];
- Val[0] = 0;
- for (int i = 1; i < l; ++i)
- {
- Val[i] = Val[i - 1] + pat.Item1[i - 1].Length + pat.Item2[i - 1];
- }
+ int textLength = T.Length;
+ (string[] patternParts, int[] dontCares) = SplitPattern(P);
+ var patternLength = patternParts.Length;
+ var Val = CalculateOffsets(patternParts, dontCares);
  var occ_P = new SortedSet<int>();
- var P_1 = pat.Item1[0];
+ var P_1 = patternParts[0];
  var occ_P1 = sa.FindOccurences(P_1.ToCharArray());
  var permitted = occ_P1.ToDictionary(i => i, v => 1);
- for (int i =0; i < l; ++i)
+ for (int i =0; i < patternLength; ++i)
  {
- var Pi = pat.Item1[i];
+ var Pi = patternParts[i];
+ var nextPatternWildcards = i<dontCares.Length ? dontCares[i] : 0;
  var occ_Pi = sa.FindOccurences(Pi.ToCharArray());
- foreach (var r in occ_Pi)
+ foreach (var pos in occ_Pi)
  {
- int r_val = r - Val[i];
- if (permitted.TryGetValue(r_val, out int c))
+ int adjustedPos = pos - Val[i];
+ if (!IsValidPos(adjustedPos,Val[i], nextPatternWildcards, textLength))
+ continue;
+ if (permitted.TryGetValue(adjustedPos, out int c))
  {
  ++c;
- permitted[r_val] = c;
- if (c == l)
- occ_P.Add(r_val);
+ permitted[adjustedPos] = c;
+ if (c == patternLength)
+ occ_P.Add(adjustedPos);
  }
  }
  }
  return occ_P;
  }
 
+ private int[] CalculateOffsets(string[] patternParts, int[] wildcards)
+ {
+ int length = patternParts.Length;
+ var offsets = new int[length]; 
+ offsets[0] = 0;
+ for (int i = 1; i < length; ++i)
+ {
+ offsets[i] = offsets[i - 1] + patternParts[i - 1].Length + wildcards[i - 1];
+ }
+ return offsets;
+ }
+
  private (string[], int[]) SplitPattern(string P)
  {
  var Ps = new List<string>();
@@ -124,6 +143,7 @@ public IEnumerable<int> FindIdcp(string T, string P)
  Ps.Add(Pi.ToString());
  Pi = new StringBuilder();
  Ks.Add(1);
+ inWildcards = true;
  }
  }
  else
@@ -135,7 +155,10 @@ public IEnumerable<int> FindIdcp(string T, string P)
  Pi.Append(ch);
  }
  }
- Ps.Add(Pi.ToString());
+ if (Pi.Length > 0) // pattern can be followed by a wildcard, and the Pi will be empty then
+ {
+ Ps.Add(Pi.ToString());
+ }
  return (Ps.ToArray(), Ks.ToArray());
  }
  }

src/UnitTests/Core/Lib/WildPatternMatcher.Tests.cs

@@ -40,12 +40,21 @@ public void Wpm_NoWildcard()
  }
 
  [Test]
- [Ignore("Get this working soon")]
- public void Wpm_Wildcard()
+ public void Wpm_PatternWithWildcardInTheMiddle()
  {
  var dcp = new WildPatternMatcher();
  var x = dcp.FindDcp("abracadabraaska", "a**a");
- Assert.AreEqual(new[] { 0, 3 }, x.ToArray());
+ Assert.AreEqual(new[] { 0, 7,11 }, x.ToArray()); 
+ }
+
+ [Test]
+ public void Wpm_PatternWithWildcardAtEnd()
+ {
+ var dcp = new WildPatternMatcher();
+ // test with a pattern that has a wildcard at the end
+ var x = dcp.FindDcp("abracadabraaska", "a**a*");
+ // the 'aska' at the end of the string should not be matched - it is not followed by any character.
+ Assert.AreEqual(new[] { 0, 7 }, x.ToArray());
  }
  }
 }