Added Trim methods

Author: linkdotnet

CHANGELOG.md

@@ -8,6 +8,9 @@ All notable changes to **ValueStringBuilder** will be documented in this file. T
 
 ## [0.8.0] - 2023-08-24
 
+### Added
+- `Trim`, `TrimStart`, `TrimEnd` are added to the string builder
+
 ### Added
 
 -   The string builder can now be used to append integers, boolean & collection of strings. `sb.AppendInt(1).AppendBool(true).AppendList([]string{"a", "b", "c"})`

stringbuilder.go

@@ -232,6 +232,72 @@ func (s *StringBuilder) Write(p []byte) (int, error) {
 	return delta, nil
 }
 
+// Trims the given characters from the start and end of the string builder or all whitespaces if no characters are given
+func (s *StringBuilder) Trim(chars ...rune) *StringBuilder {
+	return s.TrimStart(chars...).TrimEnd(chars...)
+}
+
+// Trims the given characters from the start of the string builder or all whitespaces if no characters are given
+func (s *StringBuilder) TrimStart(chars ...rune) *StringBuilder {
+	start := 0
+	trimSet := make(map[rune]bool)
+
+	if len(chars) == 0 {
+		for _, ch := range s.data[:s.position] {
+			if !isWhitespace(ch) {
+				break
+			}
+			start++
+		}
+	} else {
+		for _, ch := range chars {
+			trimSet[ch] = true
+		}
+		for _, ch := range s.data[:s.position] {
+			if _, exists := trimSet[ch]; !exists {
+				break
+			}
+			start++
+		}
+	}
+
+	if start > 0 {
+		copy(s.data, s.data[start:s.position])
+		s.position -= start
+	}
+
+	return s
+}
+
+// Trims the given characters from the start of the string builder or all whitespaces if no characters are given
+func (s *StringBuilder) TrimEnd(chars ...rune) *StringBuilder {
+	end := s.position
+	trimSet := make(map[rune]bool)
+
+	if len(chars) == 0 {
+		for i := s.position - 1; i >= 0; i-- {
+			if !isWhitespace(s.data[i]) {
+				break
+			}
+			end--
+		}
+	} else {
+		for _, ch := range chars {
+			trimSet[ch] = true
+		}
+		for i := s.position - 1; i >= 0; i-- {
+			if _, exists := trimSet[s.data[i]]; !exists {
+				break
+			}
+			end--
+		}
+	}
+
+	s.position = end
+
+	return s
+}
+
 func (s *StringBuilder) grow(lenToAdd int) {
 	// Grow times 2 until lenToAdd fits
 	newLen := len(s.data)
@@ -246,3 +312,7 @@ func (s *StringBuilder) grow(lenToAdd int) {
 
 	s.data = append(s.data, make([]rune, newLen-len(s.data))...)
 }
+
+func isWhitespace(ch rune) bool {
+	return ch == ' ' || ch == '\t' || ch == '\n' || ch == '\r'
+}

stringbuilder_test.go

@@ -377,6 +377,36 @@ func TestWriteReturnsAddedAmount(t *testing.T) {
 	}
 }
 
+func TestTrimStartWithWhitespaces(t *testing.T) {
+	s := NewStringBuilderFromString("   Hello World")
+
+	s.TrimStart()
+
+	if got := s.ToString(); got != "Hello World" {
+		t.Errorf("StringBuilder.TrimStart() = %v, want %v", got, "Hello World")
+	}
+}
+
+func TestTrimStartWithGivenCharacters(t *testing.T) {
+	s := NewStringBuilderFromString("aHello World")
+
+	s.TrimStart('a')
+
+	if got := s.ToString(); got != "Hello World" {
+		t.Errorf("StringBuilder.TrimStart() = %v, want %v", got, "Hello World")
+	}
+}
+
+func TestTrimWithWhitespacesAtTheStartAndEnd(t *testing.T) {
+	s := NewStringBuilderFromString("   Hello World   ")
+
+	s.Trim()
+
+	if got := s.ToString(); got != "Hello World" {
+		t.Errorf("StringBuilder.Trim() = %v, want %v", got, "Hello World")
+	}
+}
+
 func slicesEqual(a []int, b []int) bool {
 	if len(a) != len(b) {
 		return false