Add split utility func

main.go

@@ -1,6 +1,8 @@
 package main
 
 import "bytes"
+
+import "errors"
 import "io"
 import "os"
 import "text/template"
@@ -23,13 +25,31 @@ func ReadEnvVars(rawEnv []string) (environ map[string]string) {
 
 func WriteTemplateToStream(tplSource string, environ map[string]string, outStream io.Writer) {
     tpl := template.New("_root_")
+    tpl.Funcs(template.FuncMap{
+        "split": TplSplitStr,
+    })
     _, err := tpl.Parse(tplSource)
     if err != nil {
         panic(err)
     }
     tpl.Execute(outStream, environ)
 }
 
+func TplSplitStr(args ...interface{}) ([]string, error) {
+    rawValue := args[0].(string)
+    sep := args[1].(string)
+    limit := -1
+    if len(args) > 2 {
+        parsedLimit, ok := args[2].(int)
+        if !ok {
+            err := errors.New("Limit parameter (3rd)is not integer")
+            return nil, err
+        }
+        limit = parsedLimit
+    }
+    return strings.SplitN(rawValue, sep, limit), nil
+}
+
 func main() {
     WriteTemplateToStream(ReadTemplate(os.Stdin), ReadEnvVars(os.Environ()), os.Stdout)
 }

main_test.go

@@ -12,7 +12,8 @@ func ExampleReadEnvVars() {
     v := envMap[k]
     fmt.Printf("key '%s' has value '%s'\n", k, v)
   }
-  // Output: key 'a' has value 'A'
+  // Output:
+  // key 'a' has value 'A'
   // key 'b' has value 'b=B'
   // key 'empty' has value ''
   // key 'spaces' has value '   '
@@ -26,6 +27,24 @@ func ExampleWriteTemplateToStream_basic() {
   WriteTemplateToStream("Hello, {{ .TARGET_PLANET }}!\n", env, buf)
   WriteTemplateToStream("{{ if not .BEGIN_INVASION}}We mean you no{{ else }}Prepare yourselves for{{ end }} harm.", env, buf)
   fmt.Println(buf.String())
-  // Output: Hello, earth!
+  // Output:
+  // Hello, earth!
   // We mean you no harm.
 }
+
+func ExampleWriteTemplateToStream_strSplit() {
+  buf := new(bytes.Buffer)
+  env := map[string]string{
+    "PARTS": "a,b,c",
+  }
+  // WriteTemplateToStream("{{ split .PARTS ',' }}", env, buf)
+  WriteTemplateToStream("{{ range $i, $v := split .PARTS \",\"   }}List 1 item {{$i}} has value {{$v}}\n{{end}}", env, buf)
+  WriteTemplateToStream("{{ range $i, $v := split .PARTS \",\" 2 }}List 2 item {{$i}} has value {{$v}}\n{{end}}", env, buf)
+  fmt.Println(buf.String())
+  // Output:
+  // List 1 item 0 has value a
+  // List 1 item 1 has value b
+  // List 1 item 2 has value c
+  // List 2 item 0 has value a
+  // List 2 item 1 has value b,c
+}