2019-03-21 18:40:54 +00:00
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package hatmill
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2019-03-21 17:26:40 +00:00
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import "io"
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2019-03-29 02:18:25 +00:00
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// Term represents a fragment of HTML markup, and is one of VoidElement, ParentElement, or Text.
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2019-03-22 03:31:24 +00:00
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type Term interface {
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io.WriterTo
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2019-03-21 17:26:40 +00:00
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2019-03-22 03:31:24 +00:00
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// isHtml is a no-op method to prevent external Term implementations, because
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2019-03-21 18:40:54 +00:00
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// Go doesn't have sum types.
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isHtml()
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}
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2019-03-21 18:40:54 +00:00
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// writeStringsTo attempts to write the strings in ss to w, incrementing n by the
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// number of bytes written.
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func writeStringsTo(w io.Writer, n *int64, ss ...string) error {
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for _, s := range ss {
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nCurr, err := io.WriteString(w, s)
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*n += int64(nCurr)
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if err != nil {
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return err
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}
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}
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return nil
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2019-03-21 17:26:40 +00:00
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}
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2019-03-25 02:54:09 +00:00
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// Attrib represents an HTML attribute.
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type Attrib struct {
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Key string
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Value string
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}
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2019-03-25 02:54:09 +00:00
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// WriteTo writes a to w as an HTML attribute in the form key="value", or
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// simply key if value is empty. It returns the number of bytes written and any
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// error encountered.
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func (a Attrib) WriteTo(w io.Writer) (n int64, err error) {
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err = writeStringsTo(w, &n, a.Key)
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if err != nil {
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return
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}
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if a.Value != "" {
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err = writeStringsTo(w, &n, "='", a.Value, "'")
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}
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return
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2019-03-21 17:26:40 +00:00
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}
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2019-03-29 02:18:25 +00:00
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// VoidElement represents a void HTML element, that is one that cannot have
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// children.
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type VoidElement struct {
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TagName string
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Attribs []Attrib
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}
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func (VoidElement) isHtml() {}
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2019-03-25 02:54:09 +00:00
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// WriteTo writes the HTML markup represented by e to w, returning the number
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// of bytes written and any error encountered.
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2019-03-25 03:00:36 +00:00
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//
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// See the warning about sanitization in the (Attrib).WriteTo documentation.
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func (e VoidElement) WriteTo(w io.Writer) (n int64, err error) {
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err = writeStringsTo(w, &n, "<", e.TagName)
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if err != nil {
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return
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}
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for _, attrib := range e.Attribs {
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err = writeStringsTo(w, &n, " ")
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if err != nil {
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return
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}
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var nCurr int64
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nCurr, err = attrib.WriteTo(w)
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n += int64(nCurr)
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if err != nil {
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return
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}
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}
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err = writeStringsTo(w, &n, ">")
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return
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}
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2019-03-25 02:54:09 +00:00
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// ParentElement represents an HTML element that can have children.
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type ParentElement struct {
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VoidElement
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Children []Term
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}
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2019-03-25 02:46:38 +00:00
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func (e ParentElement) isHtml() {}
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2019-03-25 02:54:09 +00:00
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// WriteTo writes the HTML markup represented by e to w, returning the number
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// of bytes written and any error encountered.
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2019-03-25 03:00:36 +00:00
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//
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// See the warning about sanitization in the (Attrib).WriteTo documentation.
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func (e ParentElement) WriteTo(w io.Writer) (n int64, err error) {
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n, err = e.VoidElement.WriteTo(w)
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if err != nil {
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return
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}
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for _, child := range e.Children {
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var nCurr int64
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nCurr, err = child.WriteTo(w)
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n += int64(nCurr)
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if err != nil {
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return
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}
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}
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2019-03-21 17:26:40 +00:00
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2019-03-21 18:40:54 +00:00
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err = writeStringsTo(w, &n, "</", e.TagName, ">")
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return
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}
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2019-03-25 02:54:09 +00:00
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// Text represents an HTML text node.
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type Text string
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func (Text) isHtml() {}
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2019-03-21 17:26:40 +00:00
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2019-03-25 02:54:09 +00:00
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// WriteTo writes the contents of t to w, returning the number of bytes written
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2019-03-25 03:00:36 +00:00
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// and any error encountered. It does not replace special characters with HTML
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// entities; use html.EscapeString for this purpose.
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func (t Text) WriteTo(w io.Writer) (n int64, err error) {
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err = writeStringsTo(w, &n, string(t))
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return
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2019-03-21 17:26:40 +00:00
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}
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2019-03-21 18:40:54 +00:00
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// WriteDocument writes an HTML5 doctype declaration, followed by root.
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// root should probably be an <html> element.
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func WriteDocument(w io.Writer, root ParentElement) (n int64, err error) {
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err = writeStringsTo(w, &n, "<!DOCTYPE html>")
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if err != nil {
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return
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}
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var nroot int64
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nroot, err = root.WriteTo(w)
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n += nroot
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return
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}
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