Wrote new method to return 0-group of leftmost match; reorganized some functions for better clarity; made 'FindNthMatch' a method

regex/matching.go

@@ -57,6 +57,11 @@ func (g Group) isValid() bool {
 	return g.StartIdx >= 0 && g.EndIdx >= 0
 }
 
+// Simple function, makes it easier to map this over a list of matches
+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.
@@ -138,30 +143,51 @@ func pruneIndices(indices []Match) []Match {
 	return toRet
 }
 
-// FindString returns a string containing the text of the leftmost match of the regex in the given string.
+// Find returns the 0-group of the leftmost match of the regex in the given string.
+// An error value != nil indicates that no match was found.
+func (regex Reg) Find(str string) (Group, error) {
+	match, err := regex.FindNthMatch(str, 1)
+	if err != nil {
+		return Group{}, nil
+	}
+	return getZeroGroup(match), 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 {
+	indices := regex.FindAllSubmatch(str)
+	zeroGroups := funcMap(indices, getZeroGroup)
+	return zeroGroups
+}
+
+// FindString returns the text of the leftmost match of the regex in the given string.
 // The return value will be an empty string in two situations:
 //  1. No match was found
 //  2. The match was an empty string
 func (regex Reg) FindString(str string) string {
-	match, err := FindNthMatch(regex, str, 1)
+	match, err := regex.FindNthMatch(str, 1)
 	if err != nil {
 		return ""
 	}
-	return str[match[0].StartIdx:match[0].EndIdx]
+	zeroGroup := getZeroGroup(match)
+	return str[zeroGroup.StartIdx:zeroGroup.EndIdx]
 }
 
 // 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 {
-	return []string{}
-	// matches := FindAllMatches, str string)
+	zerogroups := regex.FindAll(str)
+	matchStrs := funcMap(zerogroups, func(g Group) string {
+		return str[g.StartIdx:g.EndIdx]
+	})
+	return matchStrs
 }
 
-// FindNthMatch finds the 'n'th match of the regex represented by the given start-state, with
-// the given string.
+// FindNthMatch return the 'n'th match of the regex in the given string.
 // It returns an error (!= nil) if there are fewer than 'n' matches in the string.
-func FindNthMatch(regex Reg, str string, n int) (Match, error) {
+func (regex Reg) FindNthMatch(str string, n int) (Match, error) {
 	idx := 0
 	matchNum := 0
 	str_runes := []rune(str)
@@ -180,16 +206,6 @@ func FindNthMatch(regex Reg, str string, n int) (Match, error) {
 	return nil, fmt.Errorf("invalid match index - too few matches found")
 }
 
-// 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 {
-	indices := regex.FindAllSubmatch(str)
-	zeroGroups := funcMap(indices, func(m Match) Group {
-		return m[0]
-	})
-	return zeroGroups
-}
-
 // FindAllSubmatch returns a slice of matches in the given string.
 func (regex Reg) FindAllSubmatch(str string) []Match {
 	idx := 0