Merge branch 'webner-when-function'

Author: jwilder

README.md

@@ -235,6 +235,7 @@ For example, this is a JSON version of an emitted RuntimeContainer struct:
 * *`whereNotExist $items $fieldPath`*: Like `where`, but returns only items where `$fieldPath` does not exist (is nil).
 * *`whereAny $items $fieldPath $sep $values`*: Like `where`, but the string value specified by `$fieldPath` is first split by `$sep` into a list of strings. The comparison value is a string slice with possible matches. Returns items which OR intersect these values.
 * *`whereAll $items $fieldPath $sep $values`*: Like `whereAny`, except all `$values` must exist in the `$fieldPath`.
+* *`when $condition $trueValue $falseValue`*: Returns the `$trueValue` when the `$condition` is `true` and the `$falseValue` otherwise
 
 ===
 

template.go

@@ -332,6 +332,15 @@ func trim(s string) string {
 	return strings.TrimSpace(s)
 }
 
+// when returns the trueValue when the condition is true and the falseValue otherwise
+func when(condition bool, trueValue, falseValue interface{}) interface{} {
+	if condition {
+		return trueValue
+	} else {
+		return falseValue
+	}
+}
+
 func newTemplate(name string) *template.Template {
 	tmpl := template.New(name).Funcs(template.FuncMap{
 		"closest":       arrayClosest,
@@ -363,6 +372,7 @@ func newTemplate(name string) *template.Template {
 		"whereNotExist": whereNotExist,
 		"whereAny":      whereAny,
 		"whereAll":      whereAll,
+		"when":          when,
 	})
 	return tmpl
 }

template_test.go

@@ -618,3 +618,36 @@ func TestArrayClosestNoMatch(t *testing.T) {
 		t.Fatal("Expected ''")
 	}
 }
+
+func TestWhen(t *testing.T) {
+	context := struct {
+		BoolValue   bool
+		StringValue string
+	}{
+		true,
+		"foo",
+	}
+
+	tests := templateTestList{
+		{`{{ print (when .BoolValue "first" "second") }}`, context, `first`},
+		{`{{ print (when (eq .StringValue "foo") "first" "second") }}`, context, `first`},
+
+		{`{{ when (not .BoolValue) "first" "second" | print }}`, context, `second`},
+		{`{{ when (not (eq .StringValue "foo")) "first" "second" | print }}`, context, `second`},
+	}
+
+	tests.run(t, "when")
+}
+
+func TestWhenTrue(t *testing.T) {
+	if when(true, "first", "second") != "first" {
+		t.Fatal("Expected first value")
+
+	}
+}
+
+func TestWhenFalse(t *testing.T) {
+	if when(false, "first", "second") != "second" {
+		t.Fatal("Expected second value")
+	}
+}