Add the {{prepend}} template helper to quote or indent a paragraph

adapter/handlebars/handlebars.go

@@ -12,9 +12,10 @@ import (
 )
 
 func Init(lang string, logger util.Logger) {
-	helpers.RegisterSlug(logger, lang)
 	helpers.RegisterDate(logger)
+	helpers.RegisterPrepend(logger)
 	helpers.RegisterShell(logger)
+	helpers.RegisterSlug(logger, lang)
 }
 
 // Template renders a parsed handlebars template.

adapter/handlebars/handlebars_test.go

@@ -73,16 +73,25 @@ func TestDoesntEscapeHTML(t *testing.T) {
 	)
 }
 
-func TestSlugHelper(t *testing.T) {
+func TestPrependHelper(t *testing.T) {
+	// inline
+	testString(t, "{{prepend '> ' 'A quote'}}", nil, "> A quote")
+
 	// block
+	testString(t, "{{#prepend '> '}}A quote{{/prepend}}", nil, "> A quote")
+	testString(t, "{{#prepend '> '}}A quote on\nseveral lines{{/prepend}}", nil, "> A quote on\n> several lines")
+}
+
+func TestSlugHelper(t *testing.T) {
+	// inline
 	testString(t,
-		"{{#slug}}This will be slugified!{{/slug}}",
+		`{{slug "This will be slugified!"}}`,
 		nil,
 		"this-will-be-slugified",
 	)
-	// inline
+	// block
 	testString(t,
-		`{{slug "This will be slugified!"}}`,
+		"{{#slug}}This will be slugified!{{/slug}}",
 		nil,
 		"this-will-be-slugified",
 	)

adapter/handlebars/helpers/prepend.go

@@ -0,0 +1,33 @@
+package helpers
+
+import (
+	"github.com/aymerick/raymond"
+	"github.com/mickael-menu/zk/util"
+	"github.com/mickael-menu/zk/util/strings"
+)
+
+// RegisterPrepend registers a {{prepend}} template helper which prepend a
+// given string at the beginning of each line.
+//
+// {{prepend '> ' 'A quote'}} -> "> A quote"
+// {{#prepend '> '}}A quote{{/prepend}} -> "> A quote"
+//
+// A quote on
+// several lines
+// {{/prepend}}
+//
+// > A quote on
+// > several lines
+func RegisterPrepend(logger util.Logger) {
+	raymond.RegisterHelper("prepend", func(prefix string, opt interface{}) string {
+		switch arg := opt.(type) {
+		case *raymond.Options:
+			return strings.Prepend(arg.Fn(), prefix)
+		case string:
+			return strings.Prepend(arg, prefix)
+		default:
+			logger.Printf("the {{prepend}} template helper is expecting a string as argument, received: %v", opt)
+			return ""
+		}
+	})
+}

util/strings/strings.go

@@ -0,0 +1,18 @@
+package strings
+
+import "strings"
+
+// Prepend prefixes each lines of a string with the given prefix.
+// It can be used to indent or quote (> ) a paragraph, for example.
+func Prepend(text string, prefix string) string {
+	if text == "" || prefix == "" {
+		return text
+	}
+
+	lines := strings.SplitAfter(text, "\n")
+	if len(lines[len(lines)-1]) == 0 {
+		lines = lines[:len(lines)-1]
+	}
+
+	return strings.Join(append([]string{""}, lines...), prefix)
+}

util/strings/strings_test.go

@@ -0,0 +1,19 @@
+package strings
+
+import (
+	"testing"
+
+	"github.com/mickael-menu/zk/util/assert"
+)
+
+func TestPrepend(t *testing.T) {
+	test := func(text string, prefix string, expected string) {
+		assert.Equal(t, Prepend(text, prefix), expected)
+	}
+
+	test("", "> ", "")
+	test("One line", "> ", "> One line")
+	test("One line\nTwo lines", "> ", "> One line\n> Two lines")
+	test("One line\nTwo lines\nThree lines", "> ", "> One line\n> Two lines\n> Three lines")
+	test("Newline\n", "> ", "> Newline\n")
+}