package hatmill //go:generate go run internal/codegen/codegen.go -input defs.json -elemfile element/generated.go -elempkg element -attribfile attribute/generated.go -attribpkg attribute import "io" // Term represents a fragment of HTML markup, and is one of VoidElement, ParentElement, or Text. type Term interface { io.WriterTo // isHtml is a no-op method to prevent external Term 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 } // Attrib represents an HTML attribute. type Attrib struct { Key string Value string } // WriteTo writes a to w as an HTML attribute in the form key="value", or // simply key if value is empty. It returns the number of bytes written and any // error encountered. 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 } // VoidElement represents a void HTML element, that is one that cannot have // children. type VoidElement struct { TagName string Attribs []Attrib } func (VoidElement) isHtml() {} // WriteTo writes the HTML markup represented by e to w, returning the number // of bytes written and any error encountered. // // See the warning about sanitization in the (Attrib).WriteTo documentation. func (e VoidElement) 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 } // ParentElement represents an HTML element that can have children. type ParentElement struct { VoidElement Children []Term } func (e ParentElement) isHtml() {} // WriteTo writes the HTML markup represented by e to w, returning the number // of bytes written and any error encountered. // // See the warning about sanitization in the (Attrib).WriteTo documentation. func (e ParentElement) WriteTo(w io.Writer) (n int64, err error) { n, err = e.VoidElement.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 } // Text represents an HTML text node. type Text string func (Text) isHtml() {} // WriteTo writes the contents of t to w, returning the number of bytes written // and any error encountered. It does not replace special characters with HTML // entities; use html.EscapeString for this purpose. func (t Text) WriteTo(w io.Writer) (n int64, err error) { err = writeStringsTo(w, &n, string(t)) return } // 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 }