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Started rewrite of matching algorithm, got concatenation and alternation done, kleene and zero-state stuff is next

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remotes/origin/implementPCREMatchingRules
Aadhavan Srinivasan 2 months ago
parent 5563a70568
commit 753e973d82
1 changed files with 256 additions and 206 deletions
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462
regex/matching.go
Unescape Escape View File

@ -1,7 +1,6 @@
package regex
import (
"container/heap"
"fmt"
"slices"
"sort"
@ -267,16 +266,15 @@ func findAllSubmatchHelper(start *nfaState, str []rune, offset int, numGroups in
// chosen as the match for the entire string.
// This allows us to pick the longest possible match (which is how greedy matching works).
// COMMENT ABOVE IS CURRENTLY NOT UP-TO-DATE
tempIndices := newMatch(numGroups + 1)
// tempIndices := newMatch(numGroups + 1)
foundPath := false
startIdx := offset
endIdx := offset
currentStates := &priorityQueue{}
heap.Init(currentStates)
tempStates := make([]*nfaState, 0) // Used to store states that should be used in next loop iteration
i := offset // Index in string
startingFrom := i // Store starting index
// foundPath := false
//startIdx := offset
//endIdx := offset
currentStates := make([]*nfaState, 0)
// tempStates := make([]*nfaState, 0) // Used to store states that should be used in next loop iteration
i := offset // Index in string
//startingFrom := i // Store starting index
// If the first state is an assertion, makes sure the assertion
// is true before we do _anything_ else.
@ -287,214 +285,266 @@ func findAllSubmatchHelper(start *nfaState, str []rune, offset int, numGroups in
}
}
// Increment until we hit a character matching the start state (assuming not 0-state)
if start.isEmpty == false {
for i < len(str) && !start.contentContains(str, i) {
i++
}
startIdx = i
startingFrom = i
i++ // Advance to next character (if we aren't at a 0-state, which doesn't match anything), so that we can check for transitions. If we advance at a 0-state, we will never get a chance to match the first character
}
start.threadGroups = newMatch(numGroups + 1)
// if start.isEmpty == false {
// for i < len(str) && !start.contentContains(str, i) {
// i++
// }
// startIdx = i
// startingFrom = i
// i++ // Advance to next character (if we aren't at a 0-state, which doesn't match anything), so that we can check for transitions. If we advance at a 0-state, we will never get a chance to match the first character
// }
// start.threadGroups = newMatch(numGroups + 1)
// Check if the start state begins a group - if so, add the start index to our list
if start.groupBegin {
start.threadGroups[start.groupNum].StartIdx = i
// tempIndices[start.groupNum].startIdx = i
}
//if start.groupBegin {
// start.threadGroups[start.groupNum].StartIdx = i
// tempIndices[start.groupNum].startIdx = i
//}
start.threadSP = i
heap.Push(currentStates, newPriorQueueItem(start))
currentStates = append(currentStates, start)
var foundMatch bool
// Main loop
for currentStates.Len() > 0 {
currentState := heap.Pop(currentStates)
foundPath = false
zeroStates := make([]*nfaState, 0)
// Keep taking zero-states, until there are no more left to take
// Objective: If any of our current states have transitions to 0-states, replace them with the 0-state. Do this until there are no more transitions to 0-states, or there are no more unique 0-states to take.
topStateItem := currentStates.peek()
topState := topStateItem.(*priorQueueItem).state
zeroStates, isZero := takeZeroState([]*nfaState{topState}, numGroups, i)
tempStates = append(tempStates, zeroStates...)
num_appended := 0
for isZero == true {
zeroStates, isZero = takeZeroState(tempStates, numGroups, i)
tempStates, num_appended = uniqueAppend(tempStates, zeroStates...)
if num_appended == 0 { // Break if we haven't appended any more unique values
break
}
}
if isZero == true {
currentStates.Pop()
}
for _, state := range tempStates {
heap.Push(currentStates, newPriorQueueItem(state))
}
tempStates = nil
// Take any transitions corresponding to current character
numStatesMatched := 0 // The number of states which had at least 1 match for this round
assertionFailed := false // Whether or not an assertion failed for this round
lastStateInList := false // Whether or not a last state was in our list of states
var lastStatePtr *nfaState = nil // Pointer to the last-state, if it was found
lastLookaroundInList := false // Whether or not a last state (that is a lookaround) was in our list of states
for numStatesMatched == 0 && lastStateInList == false {
if currentStates.Len() == 0 {
break
}
stateItem := heap.Pop(currentStates)
state := stateItem.(*priorQueueItem).state
matches, numMatches := state.matchesFor(str, i)
if numMatches > 0 {
numStatesMatched++
tempStates = append([]*nfaState(nil), matches...)
foundPath = true
for _, m := range matches {
if m.threadGroups == nil {
m.threadGroups = newMatch(numGroups + 1)
}
m.threadSP = state.threadSP + 1
copy(m.threadGroups, state.threadGroups)
}
}
if numMatches < 0 {
assertionFailed = true
}
if state.isLast {
if state.isLookaround() {
lastLookaroundInList = true
}
lastStateInList = true
lastStatePtr = state
}
}
if assertionFailed && numStatesMatched == 0 { // Nothing has matched and an assertion has failed
// If I'm being completely honest, I'm not sure why I have to check specifically for a _lookaround_
// state. The explanation below is my attempt to explain this behavior.
// If you replace 'lastLookaroundInList' with 'lastStateInList', one of the test cases fails.
//
// One of the states in our list was a last state and a lookaround. In this case, we
// don't abort upon failure of the assertion, because we have found
// another path to a final state.
// Even if the last state _was_ an assertion, we can use the previously
// saved indices to find a match.
if lastLookaroundInList {
break
} else {
if i == startingFrom {
i++
}
return false, []Group{}, i
}
for len(currentStates) > 0 {
currentState, _ := pop(&currentStates)
idx := currentState.threadSP
foundMatch = false
if currentState.threadGroups == nil {
currentState.threadGroups = newMatch(numGroups + 1)
currentState.threadGroups[0].StartIdx = idx
}
// Check if we can find a state in our list that is:
// a. A last-state
// b. Empty
// c. Doesn't assert anything
for _, stateItem := range *currentStates {
s := stateItem.state
if s.isLast && s.isEmpty && s.assert == noneAssert {
lastStatePtr = s
lastStateInList = true
if currentState.groupBegin {
currentState.threadGroups[currentState.groupNum].StartIdx = idx
} else if currentState.groupEnd {
currentState.threadGroups[currentState.groupNum].EndIdx = idx
} else if currentState.isKleene {
// Append the
} else if currentState.isAlternation {
rightState := currentState.rightState
rightState.threadGroups = currentState.threadGroups
rightState.threadSP = currentState.threadSP
currentStates = append(currentStates, currentState.rightState)
leftState := currentState.leftState
leftState.threadGroups = currentState.threadGroups
leftState.threadSP = currentState.threadSP
currentStates = append(currentStates, currentState.leftState)
continue
} else if currentState.contentContains(str, idx) {
foundMatch = true
allMatches := make([]*nfaState, 0)
for _, v := range currentState.transitions {
allMatches = append(allMatches, v...)
}
}
if lastStateInList && numStatesMatched == 0 { // A last-state was in the list of states. add the matchIndex to our MatchIndex list
for j := 1; j < numGroups+1; j++ {
tempIndices[j] = lastStatePtr.threadGroups[j]
}
endIdx = i
tempIndices[0] = Group{startIdx, endIdx}
if tempIndices[0].StartIdx == tempIndices[0].EndIdx {
return true, tempIndices, tempIndices[0].EndIdx + 1
} else {
return true, tempIndices, tempIndices[0].EndIdx
}
}
// Check if we can find a zero-length match
if foundPath == false {
currentStatesList := funcMap(*currentStates, func(item *priorQueueItem) *nfaState {
return item.state
})
if ok := zeroMatchPossible(str, i, numGroups, currentStatesList...); ok {
if tempIndices[0].IsValid() == false {
tempIndices[0] = Group{startIdx, startIdx}
}
}
// 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 i == startingFrom {
startIdx++
// i++
// }
if tempIndices.numValidGroups() > 0 && tempIndices[0].IsValid() {
if tempIndices[0].StartIdx == tempIndices[0].EndIdx { // If we have a zero-length match, we have to shift the index at which we start. Otherwise we keep looking at the same paert of the string over and over.
return true, tempIndices, tempIndices[0].EndIdx + 1
slices.Reverse(allMatches)
for _, m := range allMatches {
m.threadGroups = currentState.threadGroups
if currentState.assert == noneAssert {
m.threadSP = idx + 1
} else {
return true, tempIndices, tempIndices[0].EndIdx
m.threadSP = idx
}
}
return false, []Group{}, startIdx
}
currentStates = &priorityQueue{}
slices.Reverse(tempStates)
for _, state := range tempStates {
heap.Push(currentStates, newPriorQueueItem(state))
currentStates = append(currentStates, allMatches...)
}
tempStates = nil
i++
}
if currentState.isLast && foundMatch { // Last state reached
currentState.threadGroups[0].EndIdx = idx + 1
return true, currentState.threadGroups, idx + 1
// End-of-string reached. Go to any 0-states, until there are no more 0-states to go to. Then check if any of our states are in the end position.
// This is the exact same algorithm used inside the loop, so I should probably put it in a function.
if currentStates.Len() > 0 {
topStateItem := currentStates.peek()
topState := topStateItem.(*priorQueueItem).state
zeroStates, isZero := takeZeroState([]*nfaState{topState}, numGroups, i)
tempStates = append(tempStates, zeroStates...)
num_appended := 0 // Number of unique states addded to tempStates
for isZero == true {
zeroStates, isZero = takeZeroState(tempStates, numGroups, i)
tempStates, num_appended = uniqueAppend(tempStates, zeroStates...)
if num_appended == 0 { // Break if we haven't appended any more unique values
break
}
}
}
for _, state := range tempStates {
heap.Push(currentStates, newPriorQueueItem(state))
}
tempStates = nil
for _, stateItem := range *currentStates {
state := stateItem.state
// Only add the match if the start index is in bounds. If the state has an assertion,
// make sure the assertion checks out.
if state.isLast && i <= len(str) {
if state.assert == noneAssert || state.checkAssertion(str, i) {
for j := 1; j < numGroups+1; j++ {
tempIndices[j] = state.threadGroups[j]
}
endIdx = i
tempIndices[0] = Group{startIdx, endIdx}
}
}
}
if tempIndices.numValidGroups() > 0 {
if tempIndices[0].StartIdx == tempIndices[0].EndIdx { // If we have a zero-length match, we have to shift the index at which we start. Otherwise we keep looking at the same paert of the string over and over.
return true, tempIndices, tempIndices[0].EndIdx + 1
} else {
return true, tempIndices, tempIndices[0].EndIdx
}
}
if startIdx == startingFrom { // Increment starting index if we haven't moved in the string. Prevents us from matching the same part of the string over and over.
startIdx++
}
return false, []Group{}, startIdx
return false, []Group{}, i + 1
// zeroStates := make([]*nfaState, 0)
// // Keep taking zero-states, until there are no more left to take
// // Objective: If any of our current states have transitions to 0-states, replace them with the 0-state. Do this until there are no more transitions to 0-states, or there are no more unique 0-states to take.
// topStateItem := currentStates.peek()
// topState := topStateItem.(*priorQueueItem).state
// zeroStates, isZero := takeZeroState([]*nfaState{topState}, numGroups, i)
// tempStates = append(tempStates, zeroStates...)
// num_appended := 0
// for isZero == true {
// zeroStates, isZero = takeZeroState(tempStates, numGroups, i)
// tempStates, num_appended = uniqueAppend(tempStates, zeroStates...)
// if num_appended == 0 { // Break if we haven't appended any more unique values
// break
// }
// }
// if isZero == true {
// currentStates.Pop()
// }
//
// for _, state := range tempStates {
// heap.Push(currentStates, newPriorQueueItem(state))
// }
// tempStates = nil
//
// // Take any transitions corresponding to current character
// numStatesMatched := 0 // The number of states which had at least 1 match for this round
// assertionFailed := false // Whether or not an assertion failed for this round
// lastStateInList := false // Whether or not a last state was in our list of states
// var lastStatePtr *nfaState = nil // Pointer to the last-state, if it was found
// lastLookaroundInList := false // Whether or not a last state (that is a lookaround) was in our list of states
// for numStatesMatched == 0 && lastStateInList == false {
// if currentStates.Len() == 0 {
// break
// }
// stateItem := heap.Pop(currentStates)
// state := stateItem.(*priorQueueItem).state
// matches, numMatches := state.matchesFor(str, i)
// if numMatches > 0 {
// numStatesMatched++
// tempStates = append([]*nfaState(nil), matches...)
// foundPath = true
// for _, m := range matches {
// if m.threadGroups == nil {
// m.threadGroups = newMatch(numGroups + 1)
// }
// m.threadSP = state.threadSP + 1
// copy(m.threadGroups, state.threadGroups)
// }
// }
// if numMatches < 0 {
// assertionFailed = true
// }
// if state.isLast {
// if state.isLookaround() {
// lastLookaroundInList = true
// }
// lastStateInList = true
// lastStatePtr = state
// }
// }
//
// if assertionFailed && numStatesMatched == 0 { // Nothing has matched and an assertion has failed
// // If I'm being completely honest, I'm not sure why I have to check specifically for a _lookaround_
// // state. The explanation below is my attempt to explain this behavior.
// // If you replace 'lastLookaroundInList' with 'lastStateInList', one of the test cases fails.
// //
// // One of the states in our list was a last state and a lookaround. In this case, we
// // don't abort upon failure of the assertion, because we have found
// // another path to a final state.
// // Even if the last state _was_ an assertion, we can use the previously
// // saved indices to find a match.
// if lastLookaroundInList {
// break
// } else {
// if i == startingFrom {
// i++
// }
// return false, []Group{}, i
// }
// }
// // Check if we can find a state in our list that is:
// // a. A last-state
// // b. Empty
// // c. Doesn't assert anything
// for _, stateItem := range *currentStates {
// s := stateItem.state
// if s.isLast && s.isEmpty && s.assert == noneAssert {
// lastStatePtr = s
// lastStateInList = true
// }
// }
// if lastStateInList && numStatesMatched == 0 { // A last-state was in the list of states. add the matchIndex to our MatchIndex list
// for j := 1; j < numGroups+1; j++ {
// tempIndices[j] = lastStatePtr.threadGroups[j]
// }
// endIdx = i
// tempIndices[0] = Group{startIdx, endIdx}
// if tempIndices[0].StartIdx == tempIndices[0].EndIdx {
// return true, tempIndices, tempIndices[0].EndIdx + 1
// } else {
// return true, tempIndices, tempIndices[0].EndIdx
// }
// }
//
// // Check if we can find a zero-length match
// if foundPath == false {
// currentStatesList := funcMap(*currentStates, func(item *priorQueueItem) *nfaState {
// return item.state
// })
// if ok := zeroMatchPossible(str, i, numGroups, currentStatesList...); ok {
// if tempIndices[0].IsValid() == false {
// tempIndices[0] = Group{startIdx, startIdx}
// }
// }
// // 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 i == startingFrom {
// startIdx++
// // i++
// // }
// if tempIndices.numValidGroups() > 0 && tempIndices[0].IsValid() {
// if tempIndices[0].StartIdx == tempIndices[0].EndIdx { // If we have a zero-length match, we have to shift the index at which we start. Otherwise we keep looking at the same paert of the string over and over.
// return true, tempIndices, tempIndices[0].EndIdx + 1
// } else {
// return true, tempIndices, tempIndices[0].EndIdx
// }
// }
// return false, []Group{}, startIdx
// }
// currentStates = &priorityQueue{}
// slices.Reverse(tempStates)
// for _, state := range tempStates {
// heap.Push(currentStates, newPriorQueueItem(state))
// }
// tempStates = nil
//
// i++
// }
//
// // End-of-string reached. Go to any 0-states, until there are no more 0-states to go to. Then check if any of our states are in the end position.
// // This is the exact same algorithm used inside the loop, so I should probably put it in a function.
//
// if currentStates.Len() > 0 {
// topStateItem := currentStates.peek()
// topState := topStateItem.(*priorQueueItem).state
// zeroStates, isZero := takeZeroState([]*nfaState{topState}, numGroups, i)
// tempStates = append(tempStates, zeroStates...)
// num_appended := 0 // Number of unique states addded to tempStates
// for isZero == true {
// zeroStates, isZero = takeZeroState(tempStates, numGroups, i)
// tempStates, num_appended = uniqueAppend(tempStates, zeroStates...)
// if num_appended == 0 { // Break if we haven't appended any more unique values
// break
// }
// }
// }
//
// for _, state := range tempStates {
// heap.Push(currentStates, newPriorQueueItem(state))
// }
//
// tempStates = nil
//
// for _, stateItem := range *currentStates {
// state := stateItem.state
// // Only add the match if the start index is in bounds. If the state has an assertion,
// // make sure the assertion checks out.
// if state.isLast && i <= len(str) {
// if state.assert == noneAssert || state.checkAssertion(str, i) {
// for j := 1; j < numGroups+1; j++ {
// tempIndices[j] = state.threadGroups[j]
// }
// endIdx = i
// tempIndices[0] = Group{startIdx, endIdx}
// }
// }
// }
//
// if tempIndices.numValidGroups() > 0 {
// if tempIndices[0].StartIdx == tempIndices[0].EndIdx { // If we have a zero-length match, we have to shift the index at which we start. Otherwise we keep looking at the same paert of the string over and over.
// return true, tempIndices, tempIndices[0].EndIdx + 1
// } else {
// return true, tempIndices, tempIndices[0].EndIdx
// }
// }
//
// if startIdx == startingFrom { // Increment starting index if we haven't moved in the string. Prevents us from matching the same part of the string over and over.
//
// startIdx++
// }
//
// return false, []Group{}, startIdx
}

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