Replace and ReplaceRune

Author: linkdotnet

CHANGELOG.md

@@ -6,6 +6,9 @@ All notable changes to **ValueStringBuilder** will be documented in this file. T
 
 ## [Unreleased]
 
+### Added
+- Added the following methods: `ReplaceRune`, `Replace`
+
 ### Changed
 - Renamed `AsRune` to `AsRuneSlice` and included some more documentation to highlight that this is a shared memory block.
 

stringbuilder.go

@@ -79,7 +79,8 @@ func (s *StringBuilder) Remove(start int, length int) error {
 		return nil
 	}
 
-	s.data = append(s.data[:start], s.data[endIndex])
+	x := start + length
+	s.data = append(s.data[:start], s.data[x:]...)
 	s.position -= length
 
 	return nil
@@ -137,6 +138,47 @@ func (s *StringBuilder) FindAll(text string) []int {
 	return findAll(s.AsRuneSlice(), text)
 }
 
+// Replaces all occurrences of oldValue with newValue
+func (s *StringBuilder) ReplaceRune(oldValue rune, newValue rune) {
+	occurrences := s.FindAll(string(oldValue))
+
+	for _, v := range occurrences {
+		s.data[v] = newValue
+	}
+}
+
+// Replaces all occurrences of oldValue with newValue
+func (s *StringBuilder) Replace(oldValue string, newValue string) {
+	if oldValue == newValue {
+		return
+	}
+
+	occurrences := s.FindAll(oldValue)
+
+	delta := len(newValue) - len(oldValue)
+
+	for i := 0; i < len(occurrences); i++ {
+		index := occurrences[i] + delta*i
+
+		// newValue is smaller than old value
+		// We can insert the slice and remove the overhead
+		if delta < 0 {
+			copy(s.data[index:], []rune(newValue))
+			s.Remove(index+len(newValue), -delta)
+		} else if delta == 0 {
+			// Same length -> We can just replace the memory slice
+			copy(s.data[index:], []rune(newValue))
+		} else {
+			// newValue is larger than the old value
+			// First add until the old memory region
+			// and insert afterwards the rest
+			x := len(oldValue)
+			copy(s.data[index:], []rune(newValue[:x]))
+			s.Insert(index+len(oldValue), newValue[len(oldValue):])
+		}
+	}
+}
+
 func (s *StringBuilder) grow(lenToAdd int) {
 	// Grow times 2 until lenToAdd fits
 	newLen := cap(s.data)

stringbuilder_test.go

@@ -124,6 +124,19 @@ func TestRemoveWhenLengthZero(t *testing.T) {
 	}
 }
 
+func TestRemoveInTheMiddle(t *testing.T) {
+	const expected string = "Hlo World"
+	sb := NewStringBuilderFromString("Hello World")
+
+	if err := sb.Remove(1, 2); err != nil {
+		t.Errorf("Remove threw an error: %v", err)
+	}
+
+	if result := sb.ToString(); result != expected {
+		t.Errorf("Actual %q, Expected: %q", result, expected)
+	}
+}
+
 func TestInsertAtIndex(t *testing.T) {
 	const expected string = "Hello my dear and beautiful World"
 	sb := NewStringBuilderFromString("Hello World")
@@ -259,6 +272,41 @@ func TestFindAll(t *testing.T) {
 	}
 }
 
+func TestReplaceRune(t *testing.T) {
+	s := NewStringBuilderFromString("Hello")
+
+	s.ReplaceRune('l', 'm')
+
+	if got := s.ToString(); got != "Hemmo" {
+		t.Errorf("StringBuilder.ReplaceRune() = %v, want %v", got, "Hemmo")
+	}
+}
+
+func TestReplace(t *testing.T) {
+	tests := []struct {
+		name     string
+		input    string
+		oldValue string
+		newvalue string
+		want     string
+	}{
+		{"Replace Hello with Hallo", "Hello World", "Hello", "Hallo", "Hallo World"},
+		{"Replace Hello with Ha", "Hello World", "Hello", "Ha", "Ha World"},
+		{"Replace Hello with Hallöchen", "Hello World", "Hello", "Hallochen", "Hallochen World"},
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			s := NewStringBuilderFromString(tt.input)
+
+			s.Replace(tt.oldValue, tt.newvalue)
+
+			if got := s.ToString(); got != tt.want {
+				t.Errorf("StringBuilder.FindLast() = %v, want %v", got, tt.want)
+			}
+		})
+	}
+}
+
 func slicesEqual(a []int, b []int) bool {
 	if len(a) != len(b) {
 		return false