Fixed typo

cmd/unique_array.go

@@ -16,7 +16,6 @@ func (s *uniq_arr[T]) add(vals ...T) {
 			s.backingMap[item] = struct{}{}
 		}
 	}
-	return
 }
 
 func (s uniq_arr[T]) contains(val T) bool {

regex/compile.go

@@ -12,18 +12,24 @@ var notDotChars []rune
 
 // A Reg represents the result of compiling a regular expression. It contains
 // the startState of the NFA representation of the regex, and the number of capturing
-// groups in the regex.
+// groups in the regex. It also contains the expression string.
 type Reg struct {
 	start     *nfaState
 	numGroups int
+	str       string
 }
 
-// numSubexp eturns the number of sub-expressions in the given [Reg]. This is equivalent
+// NumSubexp returns the number of sub-expressions in the given [Reg]. This is equivalent
 // to the number of capturing groups.
 func (r Reg) NumSubexp() int {
 	return r.numGroups
 }
 
+// String returns the string used to compile the expression.
+func (r Reg) String() string {
+	return r.str
+}
+
 const concatRune rune = 0xF0001
 
 // Flags for shuntingYard - control its behavior
@@ -1128,7 +1134,8 @@ func thompson(re []postfixNode) (Reg, error) {
 
 	concatenate(nfa[0], &lastState)
 
-	return Reg{nfa[0], numGroups}, nil
+	// The string is empty here, because we add it in Compile()
+	return Reg{nfa[0], numGroups, ""}, nil
 
 }
 
@@ -1146,10 +1153,11 @@ func Compile(re string, flags ...ReFlag) (Reg, error) {
 	if err != nil {
 		return Reg{}, fmt.Errorf("error compiling regex: %w", err)
 	}
+	reg.str = re
 	return reg, nil
 }
 
-// MustCompile panicks if Compile returns an error. They are identical in all other respects.
+// MustCompile panics if Compile returns an error. They are identical in all other respects.
 func MustCompile(re string, flags ...ReFlag) Reg {
 	reg, err := Compile(re, flags...)
 	if err != nil {

regex/doc.go

@@ -4,6 +4,8 @@ Package regex implements regular expression search, using a custom non-bracktrac
 The engine relies completely on UTF-8 codepoints. As such, it is capable of matching characters
 from other languages, emojis and symbols.
 
+The API and regex syntax are largely compatible with that of the stdlib's [regexp], with a few key differences (see 'Key Differences with regexp').
+
 The full syntax is specified below.
 
 # Syntax
@@ -55,8 +57,8 @@ POSIX classes (inside normal character classes):
 Composition:
 
 	def				Match d, followed by e, followed by f
-	x|y				Match x or y (prefer longer one)
+	x|y				Match x or y (prefer x)
-	xy|z			Match xy or z
+	xy|z			Match xy or z (prefer xy)
 
 Repitition (always greedy, preferring more):
 
@@ -94,10 +96,11 @@ Lookarounds:
 Numeric ranges:
 
 	<x-y>			Match any number from x to y (inclusive) (x and y must be positive numbers)
+	\<x				Match a literal '<' followed by x
 
 # Key Differences with regexp
 
-The engine and the API differ from [regexp] in a number of ways, some of them very subtle.
+The engine and the API differ from [regexp] in a few ways, some of them very subtle.
 The key differences are mentioned below.
 
 1. Greediness:
@@ -132,7 +135,7 @@ Rather than using primitives for return values, my engine defines two types that
 values: a [Group] represents a capturing group, and a [Match] represents a list of groups.
 
 [regexp] specifies a regular expression that gives a list of all the matching functions that it supports. The
-equivalent expression for this engine is:
+equivalent expression for this engine is shown below. Note that 'Index' is the default.
 
 	Find(All)?(String)?(Submatch)?
 
@@ -140,7 +143,7 @@ equivalent expression for this engine is:
 
 If a function contains 'All' it returns all matches instead of just the leftmost one.
 
-If a function contains 'String' it returns the matched text, rather than the indices.
+If a function contains 'String' it returns the matched text, rather than the index in the string.
 
 If a function contains 'Submatch' it returns the match, including all submatches found by
 capturing groups.
@@ -156,5 +159,20 @@ and the input string:
 
 The 0th group would contain 'xy' and the 1st group would contain 'y'. Any matching function without 'Submatch' in its name
 returns the 0-group.
+
+# Feature Differences
+
+The following features from [regexp] are (currently) NOT supported:
+ 1. Named capturing groups
+ 2. Non-greedy operators
+ 3. Unicode character classes
+ 4. Embedded flags (flags are passed as arguments to [Compile])
+ 5. Literal text with \Q ... \E
+
+The following features are not available in [regexp], but are supported in my engine:
+ 1. Lookarounds
+ 2. Numeric ranges
+
+The goal is to shorten the first list, and expand the second.
 */
 package regex

regex/matching.go

@@ -2,7 +2,6 @@ package regex
 
 import (
 	"fmt"
-	"sort"
 )
 
 // A Match represents a match found by the regex in a given string.
@@ -14,7 +13,7 @@ import (
 // See [Reg.FindSubmatch] for an example.
 type Match []Group
 
-// a Group represents a group. It contains the start index and end index of the match
+// a Group represents a capturing group. It contains the start and index of the group.
 type Group struct {
 	StartIdx int
 	EndIdx   int
@@ -29,17 +28,6 @@ func newMatch(size int) Match {
 	return toRet
 }
 
-// Returns the number of valid groups in the match
-func (m Match) numValidGroups() int {
-	numValid := 0
-	for _, g := range m {
-		if g.StartIdx >= 0 && g.EndIdx >= 0 {
-			numValid++
-		}
-	}
-	return numValid
-}
-
 // Returns a string containing the indices of all (valid) groups in the match
 func (m Match) String() string {
 	var toRet string
@@ -58,7 +46,7 @@ func (idx Group) String() string {
 	return fmt.Sprintf("%d\t%d", idx.StartIdx, idx.EndIdx)
 }
 
-// Returns whether a group is valid (ie. whether it matched any text). It
+// IsValid returns whether a group is valid (ie. whether it matched any text). It
 // simply ensures that both indices of the group are >= 0.
 func (g Group) IsValid() bool {
 	return g.StartIdx >= 0 && g.EndIdx >= 0
@@ -69,87 +57,6 @@ func getZeroGroup(m Match) Group {
 	return m[0]
 }
 
-// takeZeroState takes the 0-state (if such a transition exists) for all states in the
-// given slice. It returns the resulting states. If any of the resulting states is a 0-state,
-// the second ret val is true.
-// If a state begins or ends a capturing group, its 'thread' is updated to contain the correct index.
-//func takeZeroState(states []*nfaState, numGroups int, idx int) (rtv []*nfaState, isZero bool) {
-//	for _, state := range states {
-//		if len(state.transitions[epsilon]) > 0 {
-//			for _, s := range state.transitions[epsilon] {
-//				if s.threadGroups == nil {
-//					s.threadGroups = newMatch(numGroups + 1)
-//				}
-//				copy(s.threadGroups, state.threadGroups)
-//				if s.groupBegin {
-//					s.threadGroups[s.groupNum].StartIdx = idx
-//					//					openParenGroups = append(openParenGroups, s.groupNum)
-//				}
-//				if s.groupEnd {
-//					s.threadGroups[s.groupNum].EndIdx = idx
-//					//					closeParenGroups = append(closeParenGroups, s.groupNum)
-//				}
-//			}
-//			rtv = append(rtv, state.transitions[epsilon]...)
-//		}
-//	}
-//	for _, state := range rtv {
-//		if len(state.transitions[epsilon]) > 0 {
-//			return rtv, true
-//		}
-//	}
-//	return rtv, false
-//}
-
-// zeroMatchPossible returns true if a zero-length match is possible
-// from any of the given states, given the string and our position in it.
-// It uses the same algorithm to find zero-states as the one inside the loop,
-// so I should probably put it in a function.
-//func zeroMatchPossible(str []rune, idx int, numGroups int, states ...*nfaState) bool {
-//	zeroStates, isZero := takeZeroState(states, numGroups, idx)
-//	tempstates := make([]*nfaState, 0, len(zeroStates)+len(states))
-//	tempstates = append(tempstates, states...)
-//	tempstates = append(tempstates, zeroStates...)
-//	num_appended := 0 // number of unique states addded to tempstates
-//	for isZero == true {
-//		zeroStates, isZero = takeZeroState(tempstates, numGroups, idx)
-//		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 {
-//		if state.isEmpty && (state.assert == noneAssert || state.checkAssertion(str, idx)) && state.isLast {
-//			return true
-//		}
-//	}
-//	return false
-//}
-
-// Prunes the slice by removing overlapping indices.
-func pruneIndices(indices []Match) []Match {
-	// First, sort the slice by the start indices
-	sort.Slice(indices, func(i, j int) bool {
-		return indices[i][0].StartIdx < indices[j][0].StartIdx
-	})
-	toRet := make([]Match, 0, len(indices))
-	current := indices[0]
-	for _, idx := range indices[1:] {
-		// idx doesn't overlap with current (starts after current ends), so add current to result
-		// and update the current.
-		if idx[0].StartIdx >= current[0].EndIdx {
-			toRet = append(toRet, current)
-			current = idx
-		} else if idx[0].EndIdx > current[0].EndIdx {
-			// idx overlaps, but it is longer, so update current
-			current = idx
-		}
-	}
-	// Add last state
-	toRet = append(toRet, current)
-	return toRet
-}
-
 func copyThread(to *nfaState, from nfaState) {
 	to.threadGroups = append([]Group{}, from.threadGroups...)
 }
@@ -164,6 +71,12 @@ func (regex Reg) Find(str string) (Group, error) {
 	return getZeroGroup(match), nil
 }
 
+// Match returns a boolean value, indicating whether the regex found a match in the given string.
+func (regex Reg) Match(str string) bool {
+	_, err := regex.Find(str)
+	return err == nil
+}
+
 // FindAll returns a slice containing all the 0-groups of the regex in the given string.
 // A 0-group represents the match without any submatches.
 func (regex Reg) FindAll(str string) []Group {
@@ -199,7 +112,37 @@ func (regex Reg) FindSubmatch(str string) (Match, error) {
 	}
 }
 
-// FindAllString is the 'all' version of FindString.
+// FindStringSubmatch is the 'string' version of [FindSubmatch]. It returns a slice of strings,
+// where the string at index i contains the text matched by the i-th capturing group.
+// The 0-th index represents the entire match.
+// An empty string at index n could mean:
+// ,
+//  1. Group n did not find a match
+//  2. Group n found a zero-length match
+//
+// A return value of nil indicates no match.
+func (regex Reg) FindStringSubmatch(str string) []string {
+	matchStr := make([]string, regex.numGroups+1)
+	match, err := regex.FindSubmatch(str)
+	if err != nil {
+		return nil
+	}
+	nonEmptyMatchFound := false
+	for i := range match {
+		if match[i].IsValid() {
+			matchStr[i] = str[match[i].StartIdx:match[i].EndIdx]
+			nonEmptyMatchFound = true
+		} else {
+			matchStr[i] = ""
+		}
+	}
+	if nonEmptyMatchFound == false {
+		return nil
+	}
+	return matchStr
+}
+
+// FindAllString is the 'all' version of [FindString].
 // It returns a slice of strings containing the text of all matches of
 // the regex in the given string.
 func (regex Reg) FindAllString(str string) []string {
@@ -244,9 +187,6 @@ func (regex Reg) FindAllSubmatch(str string) []Match {
 			indices = append(indices, matchIdx)
 		}
 	}
-	if len(indices) > 0 {
-		return pruneIndices(indices)
-	}
 
 	return indices
 }
@@ -293,8 +233,6 @@ func addStateToList(str []rune, idx int, list []nfaState, state nfaState, thread
 // Helper for FindAllMatches. Returns whether it found a match, the
 // first Match it finds, and how far it got into the string ie. where
 // the next search should start from.
-//
-//	Might return duplicates or overlapping indices, so care must be taken to prune the resulting array.
 func findAllSubmatchHelper(start *nfaState, str []rune, offset int, numGroups int) (bool, Match, int) {
 	// Base case - exit if offset exceeds string's length
 	if offset > len(str) {
@@ -303,21 +241,9 @@ func findAllSubmatchHelper(start *nfaState, str []rune, offset int, numGroups in
 	}
 	resetThreads(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).
-	// COMMENT ABOVE IS CURRENTLY NOT UP-TO-DATE
-	//	tempIndices := newMatch(numGroups + 1)
-
-	//	foundPath := false
-	//startIdx := offset
-	//endIdx := offset
 	currentStates := make([]nfaState, 0)
 	nextStates := 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.
@@ -327,29 +253,11 @@ func findAllSubmatchHelper(start *nfaState, str []rune, offset int, numGroups in
 			return false, []Group{}, i
 		}
 	}
-	// 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)
-	// 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
-	//}
 
 	start.threadGroups = newMatch(numGroups + 1)
 	start.threadGroups[0].StartIdx = i
 	currentStates = addStateToList(str, i, currentStates, *start, start.threadGroups, nil)
 	var match Match = nil
-	//	var isEmptyAndNoAssertion bool
-	// Main loop
 	for idx := i; idx <= len(str); idx++ {
 		if len(currentStates) == 0 {
 			break
@@ -371,76 +279,6 @@ func findAllSubmatchHelper(start *nfaState, str []rune, offset int, numGroups in
 					nextStates = addStateToList(str, idx+1, nextStates, *currentState.next, currentState.threadGroups, nil)
 				}
 			}
-
-			//			if currentState.groupBegin {
-			//				currentState.threadGroups[currentState.groupNum].StartIdx = idx
-			//			}
-			//			if currentState.groupEnd {
-			//				currentState.threadGroups[currentState.groupNum].EndIdx = idx
-			//			}
-
-			// Alternation - enqueue left then right state, and continue
-			//			if currentState.isAlternation {
-			//				if currentState.isKleene { // Reverse order of adding things
-			//					rightState := currentState.splitState
-			//					copyThread(rightState, currentState)
-			//					currentStates = slices.Insert(currentStates, currentStateIdx+1, *rightState)
-			//					leftState := currentState.next
-			//					copyThread(leftState, currentState)
-			//					currentStates = slices.Insert(currentStates, currentStateIdx+2, *leftState)
-			//				} else {
-			//					leftState := currentState.next
-			//					copyThread(leftState, currentState)
-			//					currentStates = slices.Insert(currentStates, currentStateIdx+1, *leftState)
-			//					rightState := currentState.splitState
-			//					copyThread(rightState, currentState)
-			//					currentStates = slices.Insert(currentStates, currentStateIdx+2, *rightState)
-			//				}
-			//				continue
-			//			}
-
-			// Empty state - enqueue next state, do _not_ increment the SP
-			//			if !currentState.isAlternation && currentState.isEmpty && currentState.assert == noneAssert { //&& currentState.groupBegin == false && currentState.groupEnd == false {
-			//				isEmptyAndNoAssertion = true
-			//			}
-			//
-			//			if currentState.contentContains(str, idx) {
-			//				foundMatch = true
-			//			}
-			//
-			//			if isEmptyAndNoAssertion || foundMatch {
-			//				nextMatch := *(currentState.next)
-			//				copyThread(&nextMatch, currentState)
-			//				if currentState.groupBegin {
-			//					//	if !stateExists(currentStates, nextMatch) {
-			//					currentStates = slices.Insert(currentStates, currentStateIdx+1, nextMatch)
-			//					//}
-			//				} else if currentState.groupEnd {
-			//					if !stateExists(currentStates, nextMatch) {
-			//						currentStates = slices.Insert(currentStates, currentStateIdx+1, nextMatch) // append(currentStates, nextMatch)
-			//					}
-			//				} else if currentState.assert != noneAssert {
-			//					if !stateExists(currentStates, nextMatch) {
-			//						currentStates = append(currentStates, nextMatch)
-			//					}
-			//				} else if currentState.isEmpty && !currentState.groupBegin && !currentState.groupEnd {
-			//					if !stateExists(currentStates, nextMatch) {
-			//						currentStates = append(currentStates, nextMatch)
-			//					}
-			//				} else {
-			//					if !stateExists(nextStates, nextMatch) {
-			//						nextStates = append(nextStates, nextMatch)
-			//					}
-			//				}
-			//			}
-			//
-			//			if currentState.isLast && len(nextStates) == 0 { // Last state reached
-			//				currentState.threadGroups[0].EndIdx = idx
-			//				if idx == currentState.threadGroups[0].StartIdx {
-			//					idx += 1
-			//				}
-			//				return true, currentState.threadGroups, idx
-			//			}
 		}
 		currentStates = append([]nfaState{}, nextStates...)
 		nextStates = nil
@@ -452,196 +290,4 @@ func findAllSubmatchHelper(start *nfaState, str []rune, offset int, numGroups in
 		return true, match, match[0].EndIdx
 	}
 	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
 }

regex/misc.go

@@ -48,49 +48,6 @@ func isNormalChar(c rune) bool {
 	return !slices.Contains(specialChars, c)
 }
 
-// Ensure that the given elements are only appended to the given slice if they
-// don't already exist. Returns the new slice, and the number of unique items appended.
-func uniqueAppend[T comparable](slc []T, items ...T) ([]T, int) {
-	num_appended := 0
-	for _, item := range items {
-		if !slices.Contains(slc, item) {
-			slc = append(slc, item)
-			num_appended++
-		}
-	}
-	return slc, num_appended
-}
-
-func uniqueAppendFunc[T any](slc []T, fn func(T, T) bool, items ...T) ([]T, int) {
-	toRet := make([]T, len(slc))
-	num_appended := 0
-	copy(toRet, slc)
-	for _, item := range items {
-		itemExists := false
-		for _, val := range slc {
-			if fn(item, val) {
-				itemExists = true
-			}
-		}
-		if !itemExists {
-			toRet = append(toRet, item)
-			num_appended++
-		}
-	}
-	return toRet, num_appended
-}
-
-// Returns true only if all the given elements are equal
-func allEqual[T comparable](items ...T) bool {
-	first := items[0]
-	for _, item := range items {
-		if item != first {
-			return false
-		}
-	}
-	return true
-}
-
 // Map function - convert a slice of T to a slice of V, based on a function
 // that maps a T to a V
 func funcMap[T, V any](slc []T, fn func(T) V) []V {

regex/nfa.go

@@ -183,7 +183,7 @@ func (s nfaState) checkAssertion(str []rune, idx int) bool {
 			strToMatch = string(runesToMatch)
 		}
 
-		regComp := Reg{startState, s.lookaroundNumCaptureGroups}
+		regComp := Reg{startState, s.lookaroundNumCaptureGroups, s.lookaroundRegex}
 		matchIndices := regComp.FindAll(strToMatch)
 
 		numMatchesFound := 0

regex/priorityQueue.go

@@ -1,89 +0,0 @@
-package regex
-
-import "container/heap"
-
-// Implement a priority queue using container/heap
-
-const (
-	min_priority int = iota
-	zerostate_priority
-	alternation_priority
-	kleene_priority
-	char_priority
-	max_priority
-)
-
-func getPriority(state *nfaState) int {
-	if state.isKleene {
-		return zerostate_priority
-	} else if state.isAlternation {
-		return alternation_priority
-	} else {
-		if state.isEmpty {
-			return zerostate_priority
-		} else {
-			return char_priority
-		}
-	}
-}
-
-type priorQueueItem struct {
-	state    *nfaState
-	priority int
-	index    int
-}
-
-func newPriorQueueItem(state *nfaState) *priorQueueItem {
-	return &priorQueueItem{
-		state:    state,
-		index:    -1,
-		priority: getPriority(state),
-	}
-}
-
-type priorityQueue []*priorQueueItem
-
-func (pq priorityQueue) Len() int {
-	return len(pq)
-}
-
-func (pq priorityQueue) Less(i, j int) bool {
-	if pq[i].priority == pq[j].priority {
-		return pq[i].index < pq[j].index
-	}
-	return pq[i].priority > pq[j].priority // We want max-heap, so we use greater-than
-}
-
-func (pq priorityQueue) Swap(i, j int) {
-	pq[i], pq[j] = pq[j], pq[i]
-	pq[i].index = i
-	pq[j].index = j
-}
-
-func (pq *priorityQueue) Push(x any) {
-	length := len(*pq)
-	item := x.(*priorQueueItem)
-	item.index = length
-	*pq = append(*pq, item)
-}
-
-func (pq *priorityQueue) Pop() any {
-	old := *pq
-	n := len(old)
-	item := old[n-1]
-	old[n-1] = nil
-	item.index = -1
-	*pq = old[0 : n-1]
-	return item
-}
-func (pq *priorityQueue) peek() any {
-	queue := *pq
-	n := len(queue)
-	return queue[n-1]
-}
-
-func (pq *priorityQueue) update(item *priorQueueItem, value *nfaState, priority int) {
-	item.state = value
-	item.priority = priority
-	heap.Fix(pq, item.index)
-}

regex/range2regex.go

@@ -109,7 +109,7 @@ func range2regex(start int, end int) (string, error) {
 		startSlc := intToSlc(rg.start)
 		endSlc := intToSlc(rg.end)
 		if len(startSlc) != len(endSlc) {
-			return "", fmt.Errorf("Error parsing numeric range")
+			return "", fmt.Errorf("error parsing numeric range")
 		}
 		for i := range startSlc {
 			if startSlc[i] == endSlc[i] {

regex/re_test.go

@@ -528,7 +528,7 @@ var groupTests = []struct {
 }{
 	{"(a)(b)", nil, "ab", []Match{[]Group{{0, 2}, {0, 1}, {1, 2}}}},
 	{"((a))(b)", nil, "ab", []Match{[]Group{{0, 2}, {0, 1}, {0, 1}, {1, 2}}}},
-	{"(0)", nil, "ab", []Match{[]Group{}}},
+	{"(0)", nil, "ab", []Match{}},
 	{"(a)b", nil, "ab", []Match{[]Group{{0, 2}, {0, 1}}}},
 	{"a(b)", nil, "ab", []Match{[]Group{{0, 2}, {1, 2}}}},
 	{"(a|b)", nil, "ab", []Match{[]Group{{0, 1}, {0, 1}}, []Group{{1, 2}, {1, 2}}}},
@@ -538,9 +538,8 @@ var groupTests = []struct {
 	{"(a+)(aa)", nil, "aaaa", []Match{[]Group{{0, 4}, {0, 2}, {2, 4}}}},
 	{"(aaaa)|(aaaa)", nil, "aaaa", []Match{[]Group{{0, 4}, {0, 4}, {-1, -1}}}},
 	{"(aaa)|(aaaa)", nil, "aaaa", []Match{[]Group{{0, 4}, {-1, -1}, {0, 4}}}},
-	{"(aaa)|(aaaa)", nil, "aaaa", []Match{[]Group{{0, 4}, {-1, -1}, {0, 4}}}},
 	{"(aaaa)|(aaa)", nil, "aaaa", []Match{[]Group{{0, 4}, {0, 4}, {-1, -1}}}},
-	{"(a)|(aa)", nil, "aa", []Match{[]Group{{0, 2}, {-1, -1}, {0, 2}}}},
+	{"(a)|(aa)", nil, "aa", []Match{[]Group{{0, 1}, {0, 1}}, []Group{{1, 2}, {1, 2}}}},
 	{"(a?)a?", nil, "b", []Match{[]Group{{0, 0}, {0, 0}}, []Group{{1, 1}, {1, 1}}}},
 	{"(a?)a?", nil, "ab", []Match{[]Group{{0, 1}, {0, 1}}, []Group{{1, 1}, {1, 1}}, []Group{{2, 2}, {2, 2}}}},
 	{"(a?)a?", nil, "aa", []Match{[]Group{{0, 2}, {0, 1}}, []Group{{2, 2}, {2, 2}}}},
@@ -578,7 +577,7 @@ var groupTests = []struct {
 	{`(bc+d$|ef*g.|h?i(j|k))`, nil, `bcdd`, []Match{}},
 	{`(bc+d$|ef*g.|h?i(j|k))`, nil, `reffgz`, []Match{[]Group{{1, 6}, {1, 6}}}},
 	{`(((((((((a)))))))))`, nil, `a`, []Match{[]Group{{0, 1}, {0, 1}, {0, 1}, {0, 1}, {0, 1}, {0, 1}, {0, 1}, {0, 1}, {0, 1}, {0, 1}}}},
-	{`(((((((((a)))))))))\41`, nil, `a`, []Match{[]Group{{0, 2}, {0, 1}, {0, 1}, {0, 1}, {0, 1}, {0, 1}, {0, 1}, {0, 1}, {0, 1}, {0, 1}}}},
+	{`(((((((((a)))))))))\41`, nil, `a!`, []Match{[]Group{{0, 2}, {0, 1}, {0, 1}, {0, 1}, {0, 1}, {0, 1}, {0, 1}, {0, 1}, {0, 1}, {0, 1}}}},
 	{`(.*)c(.*)`, nil, `abcde`, []Match{[]Group{{0, 5}, {0, 2}, {3, 5}}}},
 	{`\((.*), (.*)\)`, nil, `(a, b)`, []Match{[]Group{{0, 6}, {1, 2}, {4, 5}}}},
 
@@ -633,7 +632,7 @@ var groupTests = []struct {
 	{`(bc+d$|ef*g.|h?i(j|k))`, []ReFlag{RE_CASE_INSENSITIVE}, `BCDD`, []Match{}},
 	{`(bc+d$|ef*g.|h?i(j|k))`, []ReFlag{RE_CASE_INSENSITIVE}, `reffgz`, []Match{[]Group{{1, 6}, {1, 6}}}},
 	{`(((((((((a)))))))))`, []ReFlag{RE_CASE_INSENSITIVE}, `A`, []Match{[]Group{{0, 1}, {0, 1}, {0, 1}, {0, 1}, {0, 1}, {0, 1}, {0, 1}, {0, 1}, {0, 1}, {0, 1}}}},
-	{`(((((((((a)))))))))\41`, []ReFlag{RE_CASE_INSENSITIVE}, `A`, []Match{[]Group{{0, 2}, {0, 1}, {0, 1}, {0, 1}, {0, 1}, {0, 1}, {0, 1}, {0, 1}, {0, 1}, {0, 1}}}},
+	{`(((((((((a)))))))))\41`, []ReFlag{RE_CASE_INSENSITIVE}, `A!`, []Match{[]Group{{0, 2}, {0, 1}, {0, 1}, {0, 1}, {0, 1}, {0, 1}, {0, 1}, {0, 1}, {0, 1}, {0, 1}}}},
 	{`(.*)c(.*)`, []ReFlag{RE_CASE_INSENSITIVE}, `ABCDE`, []Match{[]Group{{0, 5}, {0, 2}, {3, 5}}}},
 	{`\((.*), (.*)\)`, []ReFlag{RE_CASE_INSENSITIVE}, `(A, B)`, []Match{[]Group{{0, 6}, {1, 2}, {4, 5}}}},
 	{`(a)(b)c|ab`, []ReFlag{RE_CASE_INSENSITIVE}, `AB`, []Match{[]Group{{0, 2}}}},
@@ -743,7 +742,7 @@ func TestFindString(t *testing.T) {
 				foundString := regComp.FindString(test.str)
 				if len(test.result) == 0 {
 					if foundString != "" {
-						t.Errorf("Expected no match got %v\n", foundString)
+						t.Errorf("Wanted no match got %v\n", foundString)
 					}
 				} else {
 					expectedString := test.str[test.result[0].StartIdx:test.result[0].EndIdx]
@@ -791,11 +790,68 @@ func TestFindSubmatch(t *testing.T) {
 				}
 			}
 			match, err := regComp.FindSubmatch(test.str)
+			if err != nil {
+				if len(test.result) != 0 {
+					t.Errorf("Wanted %v got no match\n", test.result[0])
+				}
+			} else if len(test.result) == 0 {
+				t.Errorf("Wanted no match got %v\n", match)
+			}
 			for i := range match {
 				if match[i].IsValid() {
 					if test.result[0][i] != match[i] {
 						t.Errorf("Wanted %v	Got %v\n", test.result[0], match)
 					}
+				} else {
+					if i < len(test.result) && test.result[0][i].IsValid() {
+						t.Errorf("Wanted %v	Got %v\n", test.result[0], match)
+					}
+				}
+			}
+		})
+	}
+}
+func TestFindStringSubmatch(t *testing.T) {
+	for _, test := range groupTests {
+		t.Run(test.re+"	"+test.str, func(t *testing.T) {
+			regComp, err := Compile(test.re, test.flags...)
+			if err != nil {
+				if test.result != nil {
+					panic(err)
+				}
+			}
+			matchStr := regComp.FindStringSubmatch(test.str)
+			if matchStr == nil {
+				if len(test.result) != 0 {
+					expectedStr := funcMap(test.result[0], func(g Group) string {
+						if g.IsValid() {
+							return test.str[g.StartIdx:g.EndIdx]
+						} else {
+							return ""
+						}
+					})
+					t.Errorf("Wanted %v got no match\n", expectedStr)
+				}
+			} else if len(test.result) == 0 {
+				t.Errorf("Wanted no match got %v\n", matchStr)
+			} else {
+				expectedStr := funcMap(test.result[0], func(g Group) string {
+					if g.IsValid() {
+						return test.str[g.StartIdx:g.EndIdx]
+					} else {
+						return ""
+					}
+				})
+				for i, groupStr := range matchStr {
+					if groupStr == "" {
+						if i < len(expectedStr) && expectedStr[i] != "" {
+							t.Errorf("Wanted %v	Got %v\n", expectedStr, matchStr)
+						}
+					} else {
+						if expectedStr[i] != groupStr {
+							t.Errorf("Wanted %v	Got %v\n", expectedStr, matchStr)
+						}
+					}
 				}
 			}
 		})
@@ -817,6 +873,10 @@ func TestFindAllSubmatch(t *testing.T) {
 						if test.result[i][j] != matchIndices[i][j] {
 							t.Errorf("Wanted %v	Got %v\n", test.result, matchIndices)
 						}
+					} else {
+						if i < len(test.result) && j < len(test.result[i]) && test.result[i][j].IsValid() {
+							t.Errorf("Wanted %v	Got %v\n", test.result, matchIndices)
+						}
 					}
 				}
 			}