added match value extraction

README.md

@@ -24,6 +24,7 @@ a very simple regex engine written in go.
   - [x] `( )` capturing group or subexpression
   - [x] `\n` backreference, e.g, `(dog)\1` where `n` is in `[0, 9]`
   - [x] `\k<name>` named backreference, e.g, `(?<animal>dog)\k<animal>`
+  - [x] extracting the string that matches with the regex
 - [x] `\` escape character
   - [x] support special characters - context dependant
 - [ ] better error handling in the API

check.go

@@ -50,13 +50,7 @@ func (s *State) check(inputString string, pos int, started bool, ctx *regexCheck
 					ctx.groups[groupName] = c
 				}
 			}
-		}
-	}
 
-	if s.groups != nil {
-		// if this state has groups associated with it
-		// go through each group
-		for _, capturedGroup := range s.groups {
 			// if the group ends
 			if capturedGroup.end {
 				// for each name of the captured group

lib.go

@@ -35,6 +35,40 @@ func (s *State) Test(inputString string) Result {
 	}
 }
 
+func (s *State) FindMatches(inputString string) []Result {
+	var results []Result
+	start := -1
+	for start < len(inputString) {
+		checkContext := &regexCheckContext{
+			groups: map[string]*capture{},
+		}
+		result := s.check(inputString, start, s.startOfText, checkContext)
+		if !result {
+			break
+		}
+		// prepare the result
+		groups := map[string]string{}
+
+		if result {
+			// extract strings from the groups
+			for groupName, captured := range checkContext.groups {
+				groups[groupName] = captured.string(inputString)
+				if groupName == "0" {
+					start = captured.end + 1
+				}
+			}
+		}
+
+		r := Result{
+			matches: result,
+			groups:  groups,
+		}
+
+		results = append(results, r)
+	}
+	return results
+}
+
 // Check compiles the regexString and tests the inputString against it
 func Check(regexString string, inputString string) Result {
 	return Compile(regexString).Test(inputString)

lib_test.go

@@ -138,6 +138,35 @@ func TestCheck(t *testing.T) {
 	}
 }
 
+func TestFindMatches(t *testing.T) {
+	var data = []struct {
+		regexString, input string
+		expected           []map[string]string
+	}{
+		{`[0-9]{3}-[0-9]{3}-[0-9]{2}-[0-9]{2}`, `hi 123-678-99-32 is my number, so is 239-987-63-21.`, []map[string]string{
+			{"0": "123-678-99-32"},
+			{"0": "239-987-63-21"},
+		}},
+	}
+
+	for _, test := range data {
+		testName := fmt.Sprintf("%s-%s-%v", test.regexString, test.input, test.expected)
+		t.Run(testName, func(t *testing.T) {
+			results := Compile(test.regexString).FindMatches(test.input)
+			if len(results) != len(test.expected) {
+				t.Fail()
+			}
+			for i, expected := range test.expected {
+				for k, v := range expected {
+					if results[i].groups[k] != v {
+						t.Fail()
+					}
+				}
+			}
+		})
+	}
+}
+
 func TestCheckForDev(t *testing.T) {
 	var data = []struct {
 		regexString, input string