(* html.sml
 *
 * COPYRIGHT (c) 1995 AT&T Bell Laboratories.
 * COPYRIGHT (c) 1996 AT&T Research.
 *
 * This file defines the abstract syntax of HTML documents.  The
 * AST follows the HTML 3.2 Proposed Standard.
 *)

structure HTML : HTML = 
  struct

    val htmlVersion = "3.2 Final"

    type pcdata = string
    type cdata = string
    type url = string
    type pixels = cdata
    type name = string
    type id = string

    fun match sl s = let
	  val cmp = String.collate
		(fn (c1, c2) => Char.compare(Char.toUpper c1, c2))
	  fun eq (ref s') = (cmp(s, s') = General.EQUAL)
	  in
	    List.find eq sl
	  end

  (* the different types of HTTP methods *)
    structure HttpMethod =
      struct
	type method = string ref
	val get = ref "GET"
	val put = ref "PUT"
	fun toString (ref s) = s
	val fromString = match [get, put]
      end

  (* the different types of INPUT elements *)
    structure InputType =
      struct
	type ty = string ref
	val text = ref "TEXT"
	val password = ref "PASSWORD"
	val checkbox = ref "CHECKBOX"
	val radio = ref "RADIO"
	val submit = ref "SUBMIT"
	val reset = ref "RESET"
	val file = ref "FILE"
	val hidden = ref "HIDDEN"
	val image = ref "IMAGE"
	fun toString (ref s) = s
	val fromString = match [
		text, password, checkbox,
		radio, submit, reset,
		file, hidden, image
	      ]
      end

  (* alignment attributes for IMG, APPLET and INPUT elements *)
    structure IAlign =
      struct
	type align = string ref
	val top = ref "TOP"
	val middle = ref "MIDDLE"
	val bottom = ref "BOTTOM"
	val left = ref "LEFT"
	val right = ref "RIGHT"
	fun toString (ref s) = s
	val fromString = match [top, middle, bottom, left, right]
      end

    structure HAlign =
      struct
	type align = string ref
	val left = ref "LEFT"
	val center = ref "CENTER"
	val right = ref "RIGHT"
	fun toString (ref s) = s
	val fromString = match [left, center, right]
      end

    structure CellVAlign =
      struct
	type align = string ref
	val top = ref "TOP"
	val middle = ref "MIDDLE"
	val bottom = ref "BOTTOM"
	val baseline = ref "BASELINE"
	fun toString (ref s) = s
	val fromString = match [top, middle, bottom, baseline]
      end

    structure CaptionAlign =
      struct
	type align = string ref
	val top = ref "TOP"
	val bottom = ref "BOTTOM"
	val left = ref "LEFT"
	val right = ref "RIGHT"
	fun toString (ref s) = s
	val fromString = match [top, bottom, left, right]
      end

    structure ULStyle =
      struct
	type style = string ref
	val disc = ref "DISC"
	val square = ref "SQUARE"
	val circle = ref "CIRCLE"
	fun toString (ref s) = s
	val fromString = match [disc, square, circle]
      end

    structure Shape =
      struct
	type shape = string ref
	val rect = ref "RECT"
	val circle = ref "CIRCLE"
	val poly = ref "POLY"
	val default = ref "DEFAULT"
	fun toString (ref s) = s
	val fromString = match [rect, circle, poly, default]
      end

    structure TextFlowCtl =
      struct
	type control = string ref
	val left = ref "LEFT"
	val right = ref "RIGHT"
	val all = ref "ALL"
	val none = ref "NONE"
	fun toString (ref s) = s
	val fromString = match [left, right, all, none]
      end

    datatype html = HTML of {
	version : cdata option,
	head : head_content list,
	body : body
      }

    and head_content
      = Head_TITLE of pcdata
      | Head_ISINDEX of {prompt : cdata option}
      | Head_BASE of {href : url}
      | Head_META of {
	    httpEquiv : name option,
	    name : name option,
	    content : cdata
	  }
      | Head_LINK of {
	    id : id option,
	    href : url option,
	    rel : cdata option,
	    rev : cdata option,
	    title : cdata option
	  }
    (* SCRIPT/STYLE elements are placeholders for the next version of HTML *)
      | Head_SCRIPT of pcdata
      | Head_STYLE of pcdata

    and body = BODY of {
	background : url option,
	bgcolor : cdata option,
	text : cdata option,
	link : cdata option,
	vlink : cdata option,
	alink : cdata option,
	content : block
      }

    and block
      = BlockList of block list
      | TextBlock of text
      | Hn of {
	    n : int,
	    align : HAlign.align option,
	    content : text
	  }
      | ADDRESS of block
      | P of {
	    align : HAlign.align option,
	    content : text
	  }
      | UL of {
	    ty : ULStyle.style option,
	    compact : bool,
	    content : list_item list
	  }
      | OL of {
	    ty : cdata option,
	    start : int option,
	    compact : bool,
	    content : list_item list
	  }
      | DIR of {
	    compact : bool,
	    content : list_item list
	  }
      | MENU of {
	    compact : bool,
	    content : list_item list
	  }
      | DL of {
	    compact : bool,
	    content : {dt : text list, dd : block} list
	  }
      | PRE of {
	    width : int option,
	    content : text
	  }
      | DIV of {
	    align : HAlign.align,
	    content : block
	  }
      | CENTER of block
      | BLOCKQUOTE of block
      | FORM of {
	    action : url option,
	    method : HttpMethod.method,
	    enctype : cdata option,
	    content : block		(* -(FORM) *)
	  }
      | ISINDEX of {prompt : cdata option}
      | HR of {
	    align : HAlign.align option,
	    noshade : bool,
	    size : pixels option,
	    width : cdata option
	  }
      | TABLE of {
	    align : HAlign.align option,
	    width : cdata option,
	    border : pixels option,
	    cellspacing : pixels option,
	    cellpadding : pixels option,
	    caption : caption option,
	    content : tr list
	  }

    and list_item = LI of {
	    ty : cdata option,
	    value : int option,
	    content : block
	  }

  (** table content **)
    and caption = CAPTION of {
	    align : CaptionAlign.align option,
	    content : text
	  }
    and tr = TR of {
	    align : HAlign.align option,
	    valign : CellVAlign.align option,
	    content : table_cell list
	  }
    and table_cell
      = TH of {
	    nowrap : bool,
	    rowspan : int option,
	    colspan : int option,
	    align : HAlign.align option,
	    valign : CellVAlign.align option,
	    width : pixels option,
	    height : pixels option,
	    content : block
	  }
      | TD of {
	    nowrap : bool,
	    rowspan : int option,
	    colspan : int option,
	    align : HAlign.align option,
	    valign : CellVAlign.align option,
	    width : pixels option,
	    height : pixels option,
	    content : block
	  }

  (** Text **)
    and text
      = TextList of text list
      | PCDATA of pcdata
      | TT of text
      | I of text
      | B of text
      | U of text
      | STRIKE of text
      | BIG of text
      | SMALL of text
      | SUB of text
      | SUP of text
      | EM of text
      | STRONG of text
      | DFN of text
      | CODE of text
      | SAMP of text
      | KBD of text
      | VAR of text
      | CITE of text
      | A of {
	    name : cdata option,
	    href : url option,
	    rel : cdata option,
	    rev : cdata option,
	    title : cdata option,
	    content : text		(* -(A) *)
	  }
      | IMG of {
	    src : url,
	    alt : cdata option,
	    align : IAlign.align option,
	    height : pixels option,
	    width : pixels option,
	    border : pixels option,
	    hspace : pixels option,
	    vspace : pixels option,
	    usemap : url option,
	    ismap : bool
	  }
      | APPLET of {
	    codebase : url option,
	    code : cdata,
	    name : cdata option,
	    alt : cdata option,
	    align : IAlign.align option,
	    height : pixels option,
	    width : pixels option,
	    hspace : pixels option,
	    vspace : pixels option,
	    content : text
	  }
      | PARAM of {		(* applet parameter *)
	    name : name,
	    value : cdata option
	  }
      | FONT of {
	    size : cdata option,
	    color : cdata option,
	    content : text
	  }
      | BASEFONT of {
	    size : cdata option,
	    content : text
	  }
      | BR of {
	    clear : TextFlowCtl.control option
	  }
      | MAP of {
	    name : cdata option,
	    content : area list
	  }
      | INPUT of {
	    ty : InputType.ty option,
	    name : cdata option,
	    value : cdata option,
	    checked : bool,
	    size : cdata option,
	    maxlength : int option,
	    src : url option,
	    align : IAlign.align option
	  }
      | SELECT of {
	    name : cdata,
	    size : int option,
	    content : select_option list
	  }
      | TEXTAREA of {
	    name : cdata,
	    rows : int,
	    cols : int,
	    content : pcdata
	  }
    (* SCRIPT elements are placeholders for the next version of HTML *)
      | SCRIPT of pcdata

  (* map areas *)
    and area = AREA of {
	    shape : Shape.shape option,
	    coords : cdata option,
	    href : url option,
	    nohref : bool,
	    alt : cdata
	  }

  (* SELECT options *)
    and select_option = OPTION of {
	    selected : bool,
	    value : cdata option,
	    content : pcdata
	  }

  end (* signature HTML *)