Preserve hypen when breaking a word - Fixes #16

Author: bbrks

example_test.go

@@ -197,21 +197,21 @@ func ExampleWrapper_Wrap_short() {
 }
 
 func ExampleWrapper_Wrap_hyphens() {
-	var loremIpsum = `
-In this particular example, I will spam a lot of hyphenated words, which should wrap at some point, and test the multi-breakpoint feature of this package.
-
-The girl was accident-prone, good-looking, quick-thinking, carbon-neutral, bad-tempered, sport-mad, fair-haired, camera-ready, and finally open-mouthed.
-`
+	var text = `My sister-in-law bought a state-of-the-art, energy-efficient, top-rated washing machine from a well-known, highly-recommended manufacturer based in the north-east. It was a last-minute, spur-of-the-moment decision, but the twenty-year guarantee and the user-friendly, self-cleaning features made it a no-brainer.`
 
 	w := wrap.NewWrapper()
 
-	fmt.Println(w.Wrap(loremIpsum, 80))
+	fmt.Println(w.Wrap(text, 40))
 	// Output:
-	// In this particular example, I will spam a lot of hyphenated words, which should
-	// wrap at some point, and test the multi-breakpoint feature of this package.
-	//
-	// The girl was accident-prone, good-looking, quick-thinking, carbon-neutral, bad
-	// tempered, sport-mad, fair-haired, camera-ready, and finally open-mouthed.
+	// My sister-in-law bought a state-of-the-
+	// art, energy-efficient, top-rated washing
+	// machine from a well-known, highly-
+	// recommended manufacturer based in the
+	// north-east. It was a last-minute, spur-
+	// of-the-moment decision, but the twenty-
+	// year guarantee and the user-friendly,
+	// self-cleaning features made it a no-
+	// brainer.
 }
 
 func ExampleWrapper_Wrap_prefix() {

wrapper.go

@@ -140,6 +140,7 @@ func (w Wrapper) lineBuilder(sb *strings.Builder, s string, limit int) {
 	i := strings.LastIndexAny(s[:limitByteIndex], w.Breakpoints)
 
 	breakpointWidth := 1
+	keepBreakpoint := false
 
 	// Can't wrap within the limit
 	if i < 0 {
@@ -160,9 +161,18 @@ func (w Wrapper) lineBuilder(sb *strings.Builder, s string, limit int) {
 		}
 	}
 
-	// Write this line (trim trailing breakpoints) and recurse
+	// Non-space breakpoints (like hyphen) should stay on the line
+	if breakpointWidth > 0 && s[i] != ' ' {
+		keepBreakpoint = true
+	}
+
+	// Write this line and recurse
 	sb.WriteString(w.OutputLinePrefix)
-	sb.WriteString(strings.TrimRight(s[:i], w.Breakpoints))
+	lineContent := s[:i]
+	if keepBreakpoint {
+		lineContent = s[:i+1]
+	}
+	sb.WriteString(strings.TrimRight(lineContent, " "))
 	sb.WriteString(w.OutputLineSuffix)
 	sb.WriteString(w.Newline)
 

wrapper_test.go

@@ -112,9 +112,9 @@ func TestWrapper_Breakpoints(t *testing.T) {
 		expected    string
 	}{
 		{"space only", "hello world foo bar", " ", 10, "hello\nworld foo\nbar\n"},
-		{"hyphen only", "hello-world-foo-bar", "-", 12, "hello-world\nfoo-bar\n"},
-		{"custom breakpoint", "hello|world|foo|bar", "|", 12, "hello|world\nfoo|bar\n"},
-		{"multiple custom breakpoints", "hello|world,foo;bar", "|,;", 12, "hello|world\nfoo;bar\n"},
+		{"hyphen only", "hello-world-foo-bar", "-", 12, "hello-world-\nfoo-bar\n"},
+		{"custom breakpoint", "hello|world|foo|bar", "|", 12, "hello|world|\nfoo|bar\n"},
+		{"multiple custom breakpoints", "hello|world,foo;bar", "|,;", 12, "hello|world,\nfoo;bar\n"},
 		{"no breakpoints found", "helloworldfoobar", " ", 10, "helloworldfoobar\n"},
 	}