closure.go

package javascript

import (
	"encoding/gob"
	"encoding/json"
	"strings"
)

// Closure represents a javascript function pointer that can be called by javascript at a later time.
func Closure(body string, args ...string) closure {
	return closure{body, args}
}

type closure struct {
	// Body is the body javascript of the closure
	Body string
	// Args are the names of the arguments in the argument list of the closure
	Args []string
}

// JavaScript implements the JavsScripter interface and returns the closure as javascript code.
func (c closure) JavaScript() string {
	var args string

	if c.Args != nil {
		args = strings.Join(c.Args, ", ")
	}

	return "function(" + args + ") {" + c.Body + "}"
}

// MarshalJSON implements the json.Marshaller interface.
// The output of this is designed to be unpacked by the goradd javascript file during Ajax calls.
func (c closure) MarshalJSON() (buf []byte, err error) {
	var obj = map[string]interface{}{}

	obj[JsonObjectType] = "closure"
	obj["func"] = c.Body
	obj["params"] = c.Args

	buf, err = json.Marshal(obj)
	return
}

// ClosureCall represents the result of a javascript closure that is called immediately
// context will become the "this" variable inside the closure when called.
func ClosureCall(body string, context string, args ...string) closureCall {
	return closureCall{body, context, args}
}

type closureCall struct {
	// Body is the body javascript of the closure
	Body string
	// Context is what will become the "this" var inside of the closure when called. Specifying "this" will bring the "this" from the outer context in to the closure.
	Context string
	// Args are the names of the arguments in the argument list of the closure
	Args []string
}

// JavaScript implements the JavsScripter interface and returns the closure as javascript code.
func (c closureCall) JavaScript() string {
	var args string

	if c.Args != nil {
		args = strings.Join(c.Args, ", ")
	}

	return "(function(" + args + ") {" + c.Body + "}).call(" + c.Context + ")"
}

// Implements the json.Marshaller interface. The output of this is designed to be unpacked by the goradd javascript file.
func (c closureCall) MarshalJSON() (buf []byte, err error) {
	var obj = map[string]interface{}{}

	obj[JsonObjectType] = "closure"
	obj["func"] = c.Body
	obj["params"] = c.Args
	obj["call"] = c.Context

	buf, err = json.Marshal(obj)
	return
}

func init() {
	// Register objects so they can be serialized
	gob.Register(closure{})
	gob.Register(closureCall{})
}