First commit: the bones

go.mod

@@ -0,0 +1 @@
+module gitlab.codemonkeysoftware.com/b/hatmill

hatmill.go

@@ -0,0 +1,183 @@
+package main
+
+import "fmt"
+import "io"
+import "os"
+import "strings"
+
+// Html is either Element or Text
+type Html interface {
+  io.WriterTo
+  // isHtml is a non-functional marker to differentiate Html from interface{}
+  isHtml()
+}
+
+func Reader() io.Reader {
+  // TODO in-order traversal of HTML tree to spit out bytes
+  return nil
+}
+
+func String() string {
+  panic("this could be trivially implemented with a Reader and a bytes.Buffer")
+}
+
+type Attrib struct {
+  Key string
+  Value string
+}
+
+type element struct {
+  tagName string
+  attribs []Attrib
+  empty bool
+  children []Html
+}
+
+// writeTo attempts to write the strings in ss to w, incrementing n by the
+// number of bytes written.
+func writeTo(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
+}
+
+func (a Attrib) WriteTo(w io.Writer) (n int64, err error) {
+  err = writeTo(w, &n, a.Key)
+  if err != nil {
+    return
+  }
+  if a.Value != "" {
+    err = writeTo(w, &n, "='", a.Value, "'")
+  }
+  return
+}
+
+func (e *element) WriteTo(w io.Writer) (n int64, err error) {
+  err = writeTo(w, &n, "<", e.tagName)
+  if err != nil {
+    return
+  }
+
+  for _, attrib := range e.attribs {
+    err = writeTo(w, &n, " ")
+    if err != nil {
+      return
+    }
+
+    var nCurr int64
+    nCurr, err = attrib.WriteTo(w)
+    n += int64(nCurr)
+    if err != nil {
+      return
+    }
+  }
+
+  err = writeTo(w, &n, ">")
+  if err != nil {
+    return
+  }
+
+  if !e.empty {
+    for _, child := range e.children {
+      var nCurr int64
+      nCurr, err = child.WriteTo(w)
+      n += int64(nCurr)
+      if err != nil {
+        return
+      }
+    }
+
+    err = writeTo(w, &n, "</", e.tagName, ">")
+  }
+  return
+}
+
+func (*element) isHtml() {}
+
+func emptyElement(tagName string, attribs []Attrib) Html {
+  return &element{
+    tagName: tagName,
+    attribs: attribs,
+    empty: true,
+  }
+}
+
+func elementFunc(tagName string, attribs []Attrib) func(...Html) Html {
+  return func(children ...Html) Html {
+    return &element{
+      tagName: tagName,
+      attribs: attribs,
+      children: children,
+      empty: false,
+    }
+  }
+}
+
+type text string
+
+func Text(s string) Html {
+  return text(s)
+}
+
+func (text) isHtml() {}
+
+func (t text) WriteTo(w io.Writer) (n int64, err error) {
+  err = writeTo(w, &n, string(t))
+  return
+}
+
+type rText struct {
+  io.Reader
+}
+
+func RText(r io.Reader) Html {
+  return rText{Reader: r}
+}
+
+func (rText) isHtml() {}
+
+func (rt rText) WriteTo(w io.Writer) (n int64, err error) {
+  return io.Copy(w, rt.Reader)
+}
+
+// Html5 functions
+
+func Div(attribs ...Attrib) func(children ...Html) Html {
+  return elementFunc("div", attribs)
+}
+
+func Img(attribs ...Attrib) Html {
+  return emptyElement("img", attribs)
+}
+
+func Id(id string) Attrib {
+  return Attrib{
+    Key: "id",
+    Value: id,
+  }
+}
+
+func Disabled() Attrib {
+  return Attrib {
+    Key: "disabled",
+  }
+}
+
+func main() {
+  var page = Div(Disabled(), Id("container"))(
+    Img(Id("profile-photo")),
+    Text("hello"),
+    Img(Disabled()),
+    RText(strings.NewReader("goodbye!")),
+  )
+
+  n, err := page.WriteTo(os.Stdout)
+  fmt.Println()
+  fmt.Println(n)
+  fmt.Println(err)
+}