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element.go
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element.go
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package web
import (
"bytes"
"fmt"
"io"
"strings"
)
func NewElement(Name string, childOrAttr ...interface{}) *Element {
tag := &Element{Name: Name}
tag.With(childOrAttr...)
return tag
}
func NewSimpleElement(Name string, childOrAttr ...interface{}) *Element {
tag := &Element{Name: Name}
tag.With(childOrAttr...)
tag.simple = true
return tag
}
type Element struct {
Children []interface{}
Name string
Attributes []*Attribute
// No closing tag, e.g. <br />
simple bool
}
func (t *Element) String() string {
var buf bytes.Buffer
t.WriteTo(&buf)
return buf.String()
}
func (t *Element) WriteTo(w io.Writer) (int64, error) {
enc := NewHtmlEncoder(w)
enc.Encode(t)
return enc.Written, *enc.err
}
func (t *Element) With(childOrAttr ...interface{}) *Element {
t.fill(childOrAttr...)
return t
}
func (t *Element) Text() string {
return text(t)
}
func text(t interface{}) string {
switch t := t.(type) {
case *Element:
parts := make([]string, 0)
for _, c := range t.Children {
parts = append(parts, text(c))
}
return strings.Join(parts, " ")
default:
return fmt.Sprintf("%v", t)
}
}
func (t *Element) fill(childOrAttr ...interface{}) {
for _, ca := range childOrAttr {
switch ca := ca.(type) {
case *Attribute:
t.Attributes = append(t.Attributes, ca)
default:
t.Children = append(t.Children, ca)
}
}
}
// HasAttr returns true if the named attribute is found on the
// element.
func (t *Element) HasAttr(name string) bool {
for _, a := range t.Attributes {
if a.Name == name {
return true
}
}
return false
}
func (t *Element) hasChild(name string) bool {
for _, c := range t.Children {
switch c := c.(type) {
case *Element:
if c.Name == name {
return true
}
}
}
return false
}
// Attr returns the named attribute or nil.
func (t *Element) Attr(name string) *Attribute {
for _, a := range t.Attributes {
if a.Name == name {
return a
}
}
return nil
}
// AttrVal returns attribute value if it exists, empty string otherwise.
func (t *Element) AttrVal(name string) string {
a := t.Attr(name)
if a == nil {
return ""
}
return a.Val
}
// Attr creates a new named attribute with the given value.
func Attr(name string, val interface{}) *Attribute {
return &Attribute{Name: name, Val: fmt.Sprintf("%v", val)}
}
type Attribute struct {
Name string
Val string
}
func (a *Attribute) String() string {
return fmt.Sprintf("%s=%q", a.Name, a.Val)
}
func WalkElements(root *Element, fn func(e *Element)) {
fn(root)
for _, child := range root.Children {
switch child := child.(type) {
case *Element:
WalkElements(child, fn)
}
}
}