Rockingcool/kleingrep
2
0
Fork 0
Code Issues Pull Requests Packages Projects Releases Wiki Activity

Fixed matching greediness eg. a(a|b)*a would not match 'aaa' in 'aaab'

Browse Source
This commit is contained in:
Aadhavan Srinivasan
2024-10-29 20:07:30 -04:00
parent a619fd24f6
commit 8e8e9e133f
1 changed files with 38 additions and 13 deletions
Download Patch File Download Diff File Expand all files Collapse all files

51
matching.go
View File

@@ -56,6 +56,11 @@ func findAllMatchesHelper(start *State, str string, indices []matchIndex, offset
}
currentStates = append(currentStates, start)
// Hold a list of match indices for the current run. When we
// can no longer find a match, the match with the largest range is
// chosen as the match for the entire string.
// This allows us to pick the longest possible match (which is how greedy matching works).
tempIndices := make([]matchIndex, 0)
// Main loop
for i < len(str) {
foundPath = false
@@ -74,7 +79,7 @@ func findAllMatchesHelper(start *State, str string, indices []matchIndex, offset
}
}
currentStates = append(currentStates, tempStates...)
currentStates, _ = unique_append(currentStates, tempStates...)
tempStates = nil
// Take any transitions corresponding to current character
@@ -83,20 +88,28 @@ func findAllMatchesHelper(start *State, str string, indices []matchIndex, offset
tempStates = append(tempStates, state.transitions[int(str[i])]...)
foundPath = true
}
}
if foundPath == false {
// This enables the 'greedy' behavior - last-state status is only checked if we didn't find a path forward
for _, state := range currentStates {
if state.isLast {
endIdx = i
indices, _ = unique_append(indices, matchIndex{startIdx + offset, endIdx + offset})
}
if state.isLast {
endIdx = i
tempIndices, _ = unique_append(tempIndices, matchIndex{startIdx + offset, endIdx + offset})
}
// Recursion - match with rest of string if we have nowhere to go. If we haven't moved in the string, increment the counter by 1 to ensure we don't keep trying the same string over and over
}
// Recursion - match with rest of string if we have nowhere to go. If we haven't moved in the string, increment the counter by 1 to ensure we don't keep trying the same string over and over
if foundPath == false {
if i == startingFrom {
i++
}
// Get the maximum index-range from the list
if len(tempIndices) > 0 {
indexToAdd := Reduce(tempIndices, func(i1 matchIndex, i2 matchIndex) matchIndex {
r1 := i1.endIdx - i1.startIdx
r2 := i2.endIdx - i2.startIdx
if r1 >= r2 {
return i1
}
return i2
})
indices, _ = unique_append(indices, indexToAdd)
}
return findAllMatchesHelper(start, str[i:], indices, offset+i)
}
currentStates = make([]*State, len(tempStates))
@@ -123,12 +136,24 @@ func findAllMatchesHelper(start *State, str string, indices []matchIndex, offset
tempStates = nil
for _, state := range currentStates {
// Only add the match if we the start index is in bounds
// Only add the match if the start index is in bounds
if state.isLast && startIdx+offset < len(str)+offset {
endIdx = i
indices, _ = unique_append(indices, matchIndex{startIdx + offset, endIdx + offset})
tempIndices, _ = unique_append(tempIndices, matchIndex{startIdx + offset, endIdx + offset})
}
}
// Get the maximum index-range from the list
if len(tempIndices) > 0 {
indexToAdd := Reduce(tempIndices, func(i1 matchIndex, i2 matchIndex) matchIndex {
r1 := i1.endIdx - i1.startIdx
r2 := i2.endIdx - i2.startIdx
if r1 >= r2 {
return i1
}
return i2
})
indices, _ = unique_append(indices, indexToAdd)
}
// Default
return indices