/* Copyright (C) 1992,2007 Joel Yliluoma ( http://iki.fi/bisqwit/ ) */
/* Various javascript utility functions - http://bisqwit.iki.fi/jsgames/ */

// A very handy shorthand.
function rgel(root,id) { return root.getElementById(id) }
function gel(id)       { return rgel(document,id) }
// Utilities for common form input properties
//  selectboxes
function id(id)    { return gel(id).selectedIndex }
function ids(id,v) { gel(id).selectedIndex=v }
//  checkboxes
function ch(id)    { return gel(id).checked?1:0 }
function chs(id,v) { gel(id).checked = v>0 }
//  textlines
function tx(id)    { return gel(id).value }
function txs(id,v) { gel(id).value = v }

/* Now the actual DOM functions */

function dom_wipe(block)
{
  var a, k=block.childNodes, b = k.length;
  for(a=b; a-- > 0; ) block.removeChild(k[a])
  return block
}
var clearBlock=dom_wipe;

/* Would use 'const' here, but IE does not support it. */
var dom_is_event_activator_name=
{onkeydown:1,onmouseover:1,onclick:1,onblur:1,onfocus:1,onmouseout:1,
 ondblclick:1,onmouseup:1,onmousedown:1,onkeypress:1,onkeyup:1,onchange:1,
 onload:1,onmousemove:1,onselect:1,onsubmit:1,onunload:1,onerror:1,className:1}
function dom_tag_finish_with(t, params)
{
  for(var i in params)
    if(dom_is_event_activator_name[i])
      t[i] = params[i];
    else
      t.setAttribute(i,params[i]);
  return t
}
function dom_add_children(t, children)
{
  var a, b=children.length;
  for(a=0; a<b; ++a) dom_append(t, children[a])
  return t
}

function dom_tag(t)
{
  return document.createElement(t)
}
function dom_text(content)
{
  return document.createTextNode(content)
}
function dom_tag_with(t,params)
{
  return dom_tag_finish_with(dom_tag(t), params)
}
function dom_tag_class(t,cls)
{
  return dom_tag_with(t, {className:cls})
}
function dom_tag_class_with(t,cls,params)
{
  return dom_tag_finish_with(dom_tag_class(t,cls), params)
}
function dom_tag_with_children(t,children)
{
  return dom_add_children(dom_tag(t), children)
}
function dom_tag_attr_with_children(t,params,children)
{
  return dom_add_children(dom_tag_with(t,params), children)
}
function dom_tag_class_with_children(t,cls,children)
{
  return dom_add_children(dom_tag_class(t,cls), children)
}
function dom_tag_text(t, text)
{
  return dom_tag_with_children(t, [dom_text(text)])
}
function dom_tag_attr_text(t, params, text)
{
  return dom_finish_with(dom_tag_text(t, text), params)
}
function dom_append(root,t)
{
  return root.appendChild(t)
}
function dom_rtext(t)
{ 
  /* Loads the text content from this tag. Assuming it has text content */
  var c = t.childNodes;
  if(!c) throw 'dom_rtext';
  var result='',a,b=c.length;
  for(a=0;a<b;++a) result += c[a].nodeValue;
  return result
}
function dom_rtags(root,t)
{
  /* Loads an array of matching tags */
  return root.getElementsByTagName(t) 
}
function dom_ftag(root,t)
{
  /* Loads the matching tag, throws exception if not found */
  var l = dom_rtags(root,t);
  if(l.length==0) throw 'tag '+t+' missing';
  if(l.length>1) throw 'tag '+t+' is ambiguous';
  return l[0]
}