native,internal/runtime: introduce the Env.MarkdownConverter method

This change introduces the 'Env.MarkdownConverter' method, which returns
the Markdown converter provided to the BuildTemplate function.

Author: gazerro

internal/compiler/checker.go

@@ -20,7 +20,7 @@ import (
 type checkingMod int
 
 // Converter is implemented by format converters.
-type Converter func(src []byte, out io.Writer) error
+type Converter = func(src []byte, out io.Writer) error
 
 const (
 	programMod checkingMod = iota + 1

internal/runtime/env.go

@@ -48,6 +48,10 @@ func (env *env) Fatal(v interface{}) {
 	panic(&fatalError{env: env, msg: v})
 }
 
+func (env *env) MarkdownConverter() Converter {
+	return env.conv
+}
+
 func (env *env) Print(args ...interface{}) {
 	for _, arg := range args {
 		env.doPrint(arg)

internal/runtime/vm.go

@@ -31,7 +31,7 @@ var emptyInterfaceType = reflect.TypeOf(&[]interface{}{nil}[0]).Elem()
 var emptyInterfaceNil = reflect.ValueOf(&[]interface{}{nil}[0]).Elem()
 
 // Converter is implemented by format converters.
-type Converter func(src []byte, out io.Writer) error
+type Converter = func(src []byte, out io.Writer) error
 
 // A TypeOfFunc function returns a type of a value.
 type TypeOfFunc func(reflect.Value) reflect.Type

native/native.go

@@ -9,6 +9,7 @@ package native
 
 import (
 	"context"
+	"io"
 	"reflect"
 )
 
@@ -30,6 +31,9 @@ type (
 	Markdown string
 )
 
+// Converter is implemented by format converters.
+type Converter = func(src []byte, out io.Writer) error
+
 // Env represents an execution environment.
 //
 // Each execution creates an Env value. This value is passed as the first
@@ -50,6 +54,10 @@ type Env interface {
 	// functions are not called and started goroutines are not terminated.
 	Fatal(v interface{})
 
+	// MarkdownConverter returns the Markdown converter provided to the
+	// BuildTemplate function, if one was set.
+	MarkdownConverter() Converter
+
 	// Print calls the print built-in function with args as argument.
 	Print(args ...interface{})