package hatmill
import "io"
// Html is one of EmptyElement, ParentElement, or Text.
type Html interface {
io.WriterTo
// isHtml is a no-op method to prevent external Html implementations, because
// Go doesn't have sum types.
isHtml()
}
// writeStringsTo attempts to write the strings in ss to w, incrementing n by the
// number of bytes written.
func writeStringsTo(w io.Writer, n *int64, ss ...string) error {
for _, s := range ss {
nCurr, err := io.WriteString(w, s)
*n += int64(nCurr)
if err != nil {
return err
}
}
return nil
}
type Attrib struct {
Key string
Value string
}
func (a Attrib) WriteTo(w io.Writer) (n int64, err error) {
err = writeStringsTo(w, &n, a.Key)
if err != nil {
return
}
if a.Value != "" {
err = writeStringsTo(w, &n, "='", a.Value, "'")
}
return
}
type EmptyElement struct {
TagName string
Attribs []Attrib
}
func (EmptyElement) isHtml() {}
func (e EmptyElement) WriteTo(w io.Writer) (n int64, err error) {
err = writeStringsTo(w, &n, "<", e.TagName)
if err != nil {
return
}
for _, attrib := range e.Attribs {
err = writeStringsTo(w, &n, " ")
if err != nil {
return
}
var nCurr int64
nCurr, err = attrib.WriteTo(w)
n += int64(nCurr)
if err != nil {
return
}
}
err = writeStringsTo(w, &n, ">")
return
}
type ParentElement struct {
EmptyElement
Children []Html
}
func (e *ParentElement) isHtml() {}
func (e *ParentElement) WriteTo(w io.Writer) (n int64, err error) {
n, err = e.EmptyElement.WriteTo(w)
if err != nil {
return
}
for _, child := range e.Children {
var nCurr int64
nCurr, err = child.WriteTo(w)
n += int64(nCurr)
if err != nil {
return
}
}
err = writeStringsTo(w, &n, "")
return
}
type Text string
func (Text) isHtml() {}
func (t Text) WriteTo(w io.Writer) (n int64, err error) {
err = writeStringsTo(w, &n, string(t))
return
}
// Html5 functions
func Div(attribs ...Attrib) func(children ...Html) *ParentElement {
return func(children ...Html) *ParentElement {
return &ParentElement{
EmptyElement: EmptyElement{
TagName: "div",
Attribs: attribs,
},
Children: children,
}
}
}
func Img(attribs ...Attrib) EmptyElement {
return EmptyElement{
TagName: "img",
Attribs: attribs,
}
}
func Id(id string) Attrib {
return Attrib{
Key: "id",
Value: id,
}
}
func Disabled() Attrib {
return Attrib{
Key: "disabled",
}
}
// WriteDocument writes an HTML5 doctype declaration, followed by root.
// root should probably be an element.
func WriteDocument(w io.Writer, root *ParentElement) (n int64, err error) {
err = writeStringsTo(w, &n, "")
if err != nil {
return
}
var nroot int64
nroot, err = root.WriteTo(w)
n += nroot
return
}