# File: laszlo.rnc
# Author: Oliver Steele
# 
# lzx.rnc is in the RELAXNG Compact syntax:
# http://www.thaiopensource.com/relaxng/compact/syntax.html
# 
# lzx.rng is a RELAXNG schema:
# http://www.oasis-open.org/committees/relax-ng/
# * P_LZ_COPYRIGHT_BEGIN ******************************************************
# * Copyright 2001-2004 Laszlo Systems, Inc.  All Rights Reserved.            *
# * Use is subject to license terms.                                          *
# * P_LZ_COPYRIGHT_END ********************************************************

#default namespace = "http://www.laszlosystems.com/2003/05/lzx"
namespace a = "http://relaxng.org/ns/compatibility/annotations/1.0"
namespace lza = "http://www.laszlosystems.com/annotations/1.0"
namespace rng = "http://relaxng.org/ns/structure/1.0"

# Literals
booleanLiteral = xsd:boolean
colorLiteral = string
numberLiteral = xsd:double
sizeLiteral = xsd:double { minInclusive = "0" }
constraint =
  xsd:string { pattern = "$(immediately|once|always)?\{.*\}" }
# Attribute value types
boolean = booleanLiteral | constraint
color = colorLiteral | constraint
script = string
expression = string
reference = string
number = numberLiteral | constraint
size = sizeLiteral | constraint
numberExpression = string
sizeExpression = string
css = string
opacity =
  xsd:double { minInclusive = "0.0" maxInclusive = "1.0" }
  | constraint
# Grammar
start = canvas | viewElement | library
canvas =
  
  ## The canvas is the container for all views within an application.
  element canvas {
    idAttribute?
    & oninitAttribute?
    & 
      ## The width of the canvas.
      [ a:defaultValue = "800" ] attribute width { sizeLiteral }?
    & 
      ## The height of the canvas.
      [ a:defaultValue = "600" ] attribute height { sizeLiteral }?
    & 
      ## The background color of the canvas.
      [ a:defaultValue = "white" ] attribute bgcolor { colorLiteral }?
    & 
      ## The string that is used in the browser window.
      [ a:defaultValue = "Laszlo Application" ]
      attribute title { string }?
    & 
      ## The default font for views in this application.
      [ a:defaultValue = "lztahoe8" ] attribute font { string }?
    & 
      ## The default size for views in this application.
      [ a:defaultValue = "8" ] attribute fontsize { size }?
    & 
      ## The default font style for views in this application.  The empty string
      ## is interpreted as 'plain'.
      [ a:defaultValue = "" ]
      attribute fontstyle {
        "bold" | "italic" | "bold italic" | "plain" | ""
      }?
    & attribute layout { css }?
    & 
      ## If false, disables validation against the schema during compilation
      [ a:defaultValue = "true" ] attribute validate { booleanLiteral }?
    & 
      ## If true, the application is compiled in debug mode, and a
      ## debugger window will appear when the application is loaded.
      ## Runtime errors (calls to undefined methods or function
      ## functions, references to undefined properties or variables) are
      ## detected and logged to the debugger window.  (Note: debug
      ## mode may cause the application to run more slowly, even if the
      ## debugger window is not visible.)  Debug mode can also be enabled at
      ## runtime by loading the application using the @c{?debug=true}
      ## option.
      [ a:defaultValue = "false" ] attribute debug { booleanLiteral }?
    & 
      ## If present, specifies the maximum width in pixels of any output text field.
      ## Text which extends beyond this width will be clipped.
      ## If this attribute is omitted, it defaults to the canvas width.
      attribute maxtextwidth { sizeLiteral }?
    & 
      ## If present, specifies the maximum height in pixels of any output text field.
      ## Text which extends beyond this height will be clipped.
      ## If this attribute is omitted, it defaults to the canvas height.
      attribute maxtextheight { sizeLiteral }?
    & 
      ## A list of names for libraries that are included in the application.
      [ a:defaultValue = "" ] attribute libraries { string }?
    & connection?
    & splash?
    & datapathChildren
    & toplevelElements
    & 
      ## The lpsversion of this lzx application.
      [ a:defaultValue = "1.1" ] attribute version { string }?
  }
library = element library { (toplevelElements & datapointer*) }
toplevelElements =
  (viewElement | scriptElement | asset | font)*
  & datasource*
  & connectiondatasource*
  & dataset*
  & debugger?
  & command*
  & objectElements
  & class*
  & includeElement*
  & library*
  & layout*
debugger =
  
  ## The debug element specifies the attributes of the runtime
  ## debugger.  This element only takes effect if either the
  ## @c{canvas} @a{debug} attribute is true or the application is
  ## loaded using the @c{?debug=true} option.
  [ lza:since = "1.1" ]
  element debug {
    
    ## The width of the debugger window.
    [ a:defaultValue = "325" ] attribute width { size }?
    & 
      ## The height of the debugger window.
      [ a:defaultValue = "125" ] attribute height { size }?
    & 
      ## The x position of the debugger window.
      [ a:defaultValue = "10" ] attribute x { numberExpression }?
    & 
      ## The y position of the debugger window.
      [ a:defaultValue = "10" ] attribute y { numberExpression }?
    & 
      ## The debugger window font 
      [ a:defaultValue = "debugger-font" ] attribute font { string }?
    & 
      ## The point size of the font
      [ a:defaultValue = "8" ] attribute fontsize { size }?
  }
includeElement =
  element include {
    
    ## A reference to a target file whose content is included in the
    ## application that contains this include element.
    attribute href { xsd:anyURI }
    & 
      ## If this attribute has the value @c{text}, the content of the
      ## target file is included as text.  Otherwise, it is read as XML.
      [ a:defaultValue = "xml" ] attribute type { "text" | "xml" }?
  }
# 
# Attributes
#
idAttribute =
  
  ## A unique identifier for this element.  Can be used as a global
  ## variable name in JavaScript code.
  [ lza:modifiers = "final" ] attribute id { xsd:ID }
srcAttribute =
  
  ## The path of a file that contains the source for this object.
  [ lza:modifiers = "final" ] attribute src { xsd:anyURI }
nameAttribute =
  
  ## The name of a variable that will be set to this object when the
  ## application is started.  If this element is directly within a
  ## @e{canvas} or @e{library} element, the global variable and the canvas
  ## property with this name will be set to this object.  If this
  ## element is within another object, that object's property with
  ## this name will be set to this object.
  [ lza:modifiers = "final" ] attribute name { token }
oninitAttribute =
  
  ## The oninit script is executed once, after the element's
  ## children, if any, have been initialized.
  attribute oninit { script }
objectAttributes =
  idAttribute?,
  nameAttribute?,
  oninitAttribute?,
  
  ## The execution of a @c{<node>}'s @c{init} method and sending of
  ## the @c{oninit} event is under the control of its @a{initstage}
  ## attribute, as follows:
  ## <dl>
  ## <dt>@c{immediate}.</dt><dd>The @c{init} method is called immediately as the
  ## last stage of @a{instantiation}.
  ## </dd>
  ## <dt>@c{early}.</dt><dd>The @c{init} method is called immediately after the
  ## view and its children have been @a{instantiated}.
  ## </dd>
  ## <dt>@c{normal}.</dt><dd>The @c{init} method is called when the parent is
  ## @a{initialized}.
  ## </dd>
  ## <dt>@c{late}.</dt><dd>The @c{init} method is called during idle time.
  ## To check whether @c{init} has been called, check the @c{isinited}
  ## property.  Force calling @c{init} using the
  ## @c{completeInstantiation} method.
  ## </dd>
  ## <dt>@c{defer}.</dt><dd>The @c{init} method will not be called unless
  ## explicitly requested by the @c{completeInstantation} method.
  ## </dd>
  ## </dl>
  [ a:defaultValue = "normal" lza:modifiers = "final" ]
  attribute initstage {
    "early" | "normal" | "late" | "immediate" | "defer"
  }?,
  
  ## Specifies the data source for this node and its children.
  ## If the value begins with an identifier followed by a colon, the
  ## identifier names a dataset, and the portion of the string after
  ## the colon is an XPath description of a portion of the data.
  ## Otherwise the entire attribute value is an XPath description of
  ## the data, relative to the data source of this node's parent element.
  ## Examples: "mydata:", "mydata:/a/b", "/a/b".
  attribute datapath { string }?
viewAttributes =
  objectAttributes,
  
  ## The opacity of the view's contents. @c{1.0} is opaque; @c{0.0} is
  ## totally transparent (invisible).
  [ a:defaultValue = "1.0" ] attribute opacity { opacity }?,
  attribute bgcolor { color }?,
  
  ## The cursor to display when the mouse is over this view. Any
  ## resource can be used as a cursor. This attribute can be set for
  ## any view with clickable=true, or any view whose class defaults
  ## clickable to true.
  attribute cursor { token }?,
  
  ## If true, this view intercepts click events; otherwise they are passed
  ## to its container.  This defaults to true if the view defines a mouse
  ## event handler or a cursor.
  attribute clickable { boolean }?,
  
  ## If true, this view "traps" the focus, for example in a window or dialog.
  ## See focus manager (LzFocus) for more details.
  attribute focustrap { boolean }?,
  
  ## If true, this view will receive focus events.
  ## See focus manager (LzFocus) for more details.
  attribute focusable { boolean }?,
  
  ## If this view has a multi-frame resource, this allows setting which
  ## resource frame is displayed.  Defaults to the first frame (1).
  [ a:defaultValue = "0" ] attribute frame { number }?,
  
  ## A color to use to render object that appears inside this view,
  ## which includes any vector or bitmap art in the view's resource
  ## and any contained views.
  attribute fgcolor { color }?,
  
  ## The font to use for any @c{<text>} or @c{<inputtext>} elements that
  ## appear inside this view. Like all the font properties
  ## (<code>fontstyle</code> and <code>fontsize</code> too) these
  ## properties cascade down the view hierarchy until a new value is
  ## specified. When the font attributes are modified at runtime,
  ## using JavaScript, the font is changed for the view itself, not
  ## for any of its subviews.
  attribute font { string }?,
  
  ## The style to use to render text fields that appear inside of
  ## this view. Once of "plain", "bold" , "italic" or "bolditalic".
  attribute fontstyle { string }?,
  
  ## Pixel size to use to render text which appears inside this
  ## view. The default is 8.
  attribute fontsize { size }?,
  
  ## A resource that is presented in the background of this view.
  ## The value can be either the name of a resource defined with @c{<resource>},
  ## a URL, or a pathname.  If the value is a URL, the resource is requested
  ## when the view is displayed.  If it's a pathname, the file named by
  ## the pathname is compiled into the application, and attached to this view.
  attribute resource { string }?,
  
  ## Clip the view's contents to its size.
  [ a:defaultValue = "false" lza:modifiers = "final" ]
  attribute clip { boolean }?,
  [ a:defaultValue = "left" lza:modifiers = "final" ]
  attribute align { "left" | "center" | "right" }?,
  
  ## Creates a constraint on the view's y position which is a function
  ## of its height and its parent's height. The default for this is
  ## "top".
  [ a:defaultValue = "top" ]
  attribute valign { "top" | "middle" | "bottom" }?,
  
  ## A CSS property: value sequence of layout parameters, which are
  ## used to create a layout that is attached to this view.  If there
  ## is a class property, it names the class of the layout; otherwise
  ## simplelayout is used.  Examples: "axis: x", "class: constantlayout; 
  ## axis: y"; "axis: x; spacing: 5".
  ## 
  ## <pre class="program" id="layout">
  ## &lt;view layout=&quot;axis:x; spacing:20&quot;&gt;
  ##     &lt;view bgcolor=&quot;red&quot; width=&quot;20&quot; height=&quot;20&quot;/&gt;
  ##     &lt;view bgcolor=&quot;red&quot; width=&quot;20&quot; height=&quot;20&quot;/&gt;
  ##     &lt;view bgcolor=&quot;red&quot; width=&quot;20&quot; height=&quot;20&quot; /&gt;
  ## &lt;/view>
  ## </pre>
  [ lza:modifiers = "final" ] attribute layout { css }?,
  [ lza:modifiers = "final" ] attribute placement { string }?,
  
  ## The view system supports sub-pixel positioning to enable smooth
  ## animation. This may be turned off to make the view snap to a
  ## pixel boundary by setting pixellock to true.
  [ a:defaultValue = "false" lza:modifiers = "final" ]
  attribute pixellock { booleanLiteral }?,
  [ a:defaultValue = "0" ] attribute rotation { numberExpression }?,
  
  ## Specifies whether to present the resource attached to this view.
  [ a:defaultValue = "0" ] attribute xoffset { numberExpression }?,
  
  ## Specifies a translation point for drawing of this view. If the xoffset
  ## is set, then rotation and x position will be calculated by first adding
  ## the xoffset.
  [ a:defaultValue = "0" ] attribute yoffset { numberExpression }?,
  
  ## Specifies a translation point for drawing of this view. If the yoffset
  ## is set, then rotation and y position will be calculated by first adding
  ## the yoffset.
  [ a:defaultValue = "true" ] attribute play { boolean }?,
  # [a:defaultValue="true"]
  
  ## For a view that contains multiple elements, specifies whether one
  ## or more can be selected.
  attribute selectiontype {
    "none" | "single" | "toggle" | "multi" | "range"
  }?,
  
  ## Setting <code>stretches</code> causes a view to change its
  ## coordinate space so that everything it contains (resources and
  ## other views) fit exactly into the view's width and/or height. The
  ## default for this property is "none". This is used to resize a
  ## view's contents by setting its width and/or height.
  attribute stretches { "width" | "height" | "both" }?,
  [ a:defaultValue = "true" ] attribute visible { boolean }?,
  attribute width { sizeExpression }?,
  attribute height { sizeExpression }?,
  
  ## The horizontal offset of this view's upper left corner from the
  ## upper left corner of its container.
  [ a:defaultValue = "0" ] attribute x { numberExpression }?,
  
  ## The vertical offset of this view's upper left corner from the
  ## upper left corner of its container
  [ a:defaultValue = "0" ] attribute y { numberExpression }?,
  
  ## The horizontal scaling applied to the view's resource. If xscale
  ## is set, the view stretches in its x axis. A value of 1 means that
  ## the resource will be distorted in the horizontal axis.
  [ a:defaultValue = "1.0" ] attribute xscale { numberExpression }?,
  
  ## The vertical scaling applied to the view's resource. If yscale is
  ## set, the view stretches in its y axis. A value of 1 means that
  ## the resource will be distorted in the vertical axis.
  [ a:defaultValue = "1.0" ] attribute yscale { numberExpression }?,
  
  ## A list of CSS property names and values that configure the
  ## behavior of objects, such as data binding and view layouts, that
  ## operate on this view.
  [ lza:modifiers = "final" ] attribute options { css }?,
  eventAttributes
eventAttributes =
  
  ## The onclick script is executed when the pointing device button is
  ## clicked over an element.
  attribute onclick { script }?,
  
  ## The ondblclick script is executed when the pointing device button
  ## is double clicked over an element.
  attribute ondblclick { script }?,
  
  ## The onmousedown script is executed when the pointing device button is
  ## pressed over an element.
  attribute onmousedown { script }?,
  
  ## The onmouseup script is executed when the pointing device button is
  ## released over an element.
  attribute onmouseup { script }?,
  
  ## The onmouseover script is executed when the pointing device is
  ## moved onto an element.
  attribute onmouseover { script }?,
  
  ## The onmouseout script is executed when the point device is moved
  ## so that is is no longer over an element.
  attribute onmouseout { script }?,
  
  ## The onfocus script is executed when an element receives focus
  ## either by the pointing device or by tabbing navigation.
  attribute onfocus { script }?,
  
  ## The onblur script is executed when an element loses focus either
  ## by the pointing device or by tabbing navigation.
  attribute onblur { script }?,
  
  ## The onkeydown script is executed when this view has the focus and
  ## a key is pressed down.  Multiple key down events are sent for a
  ## key that is held down.  If you want the script executed only
  ## once, use onkeyup.
  attribute onkeydown { script }?,
  
  ## The onkeyup script is executed when this view has the focus and a
  ## key is released.
  attribute onkeyup { script }?,
  attribute onselect { script }?,
  
  ## The ondata script is executed when a view's datapath gets new
  ## data, due either to a change in the dataset or a change in the
  ## parent datapath.
  attribute ondata { script }?
# 
# View Content
#
viewContent = viewAttributes & viewContentElements
viewContentElements = objectElements
viewContentElements &=
  includeElement*
  & datapathChildren
  & viewElement*
  & element dataselectionmanager {
      idAttribute?
      & nameAttribute?
      & attribute toggle { boolean }?
      & oninitAttribute?
      & objectElements
    }?
  & element selectionmanager {
      idAttribute?
      & nameAttribute?
      & attribute toggle { boolean }?
      & oninitAttribute?
      & objectElements
    }*
  & layout*
viewContentElements &= command*
command =
  element command {
    idAttribute?,
    nameAttribute?,
    attribute onselect { script }?,
    attribute active { boolean }?,
    attribute key { expression }?,
    oninitAttribute?,
    objectElements
  }
animator =
  
  ## Animates a view property to a value over a duration.  For
  ## example, @c{<view><animate attribute="opacity" from="0" to="1"
  ## duration="1000"/></view>} defines a view that fades in over the
  ## course of a second (1000ms).
  element animator { animatorContent }
animatorgroup =
  
  ## Any attribute that is legal in @e{animator} is legal in
  ## @e{animatorgroup}. These attributes are then cascaded to the
  ## animators contained within.
  ## 
  ## Events (such as onstart, onstop, etc.), name, and id, however, are
  ## not cascaded.  Also, "start" defined at the group level is
  ## effectively cascaded to the animators, meaning that the start
  ## attribute is ignored in the animators themselves.
  element animatorgroup {
    [ a:defaultValue = "sequential" ]
    attribute process { "sequential" | "simultaneous" }?
    & animatorContent
  }
animatorContent =
  idAttribute?
  & nameAttribute?
  & oninitAttribute?
  & objectElements
  & 
    ## The name of the attribute whose value is animated.  This
    ## attribute is required on an animator, unless the animator is
    ## inside an animatorgroup that specifies an attribute.
    attribute attribute { token }?
  & 
    ## Whether to start the animation instantly (the default),
    ## or wait for a script command.
    [ a:defaultValue = "true" ] attribute start { boolean }?
  & 
    ## The start value for the animation.  Defaults to the
    ## targeted attribute's current value.
    attribute from { number }?
  & 
    ## The final value for the targeted attribute.
    attribute to { number }?
  & 
    ## The duration of the animation, in milliseconds (1000 = 1 second).
    attribute duration {
      xsd:float { minInclusive = "0" }
      | constraint
    }?
  & [ a:since = "1.1" a:defaultValue = "false" ]
    attribute indirect { boolean }?
  & 
    ## Whether the to value is relative to the initial value of the
    ## attribute (@c{true}), or is absolute (@c{false}).
    [ a:defaultValue = "false" ] attribute relative { boolean }?
  & [ a:defaultValue = "easeboth" ]
    attribute motion { "linear" | "easein" | "easeout" | "easeboth" }?
  & 
    ## Executed when the animator starts.  This code is executed
    ## multiple times if the animator repeats.
    attribute onstart { script }?
  & 
    ## Executed when the animator finishes.
    attribute onstop { script }?
  & 
    ## The number of times to repeat the animation.  This should be a
    ## positive integer, or 'Infinity'.  Changes to the repeat value
    ## take effect, after the animation is finished and then restarted.
    [ lza:since = "1.1" ]
    attribute repeat {
      xsd:integer { minInclusive = "1" }
      | "Infinity"
      | constraint
    }?
  & 
    ## The paused state of the animator. If true, the animator will stop. When
    ## changed to false, the animator will resume from its current location
    [ a:defaultValue = "false" ] attribute paused { boolean }?
# 
# View elements
#
viewElement =
  
  ## A view is the basic displayable Laszlo object. One view controls
  ## one displayable resource. The view system is strictly
  ## hierarchical. A view has a single parent but can have multiple
  ## children.
  ## 
  ## The evaluation of a view occurs in three phases:
  ## 
  ## 1. @a{Construction}.  The object representing the view is
  ## created, and attributes with constant initial values are filled
  ## in.
  ## 
  ## 2. @a{Instantiation}.  The attributes with dynamic initial values
  ## are filled in (which includes the @a{construction} and
  ## @a{instantation} of any child views), the @c{initialize} method
  ## is executed, and the @c{onconstruct} event is sent.
  ## 
  ## 3. @a{Initialization}.  The @c{init} method is executed and the
  ## @c{oninit} event is sent.
  ## 
  ## Note that @a{construction} and @a{instantiation} occur
  ## sequentially, but that @a{intialization} may be arbitrarily
  ## delayed, depending on the value of the @a{initstage} attribute.
  ## Attributes with dynamic initial values may not depend on other
  ## attributes with dynamic initial values, nor on the @c{initialize}
  ## or @c{init} methods having been run.
  element view { viewContent }
  | 
    ## HTML text.
    ## 
    ## A text view which is not given an explicit width will default
    ## to have a width which is the length of the longest line. Given
    ## that the initial text content is normalized according to HTML
    ## normalization rules, and if you do not specify an explicit
    ## width, the only way a linebreak will occur is if you have an
    ## explicit HTML linebreak code such as @c{<br/>}, @c{<p/>} or a
    ## newline inside of the text contents of a @c{<pre>} element.
    ## 
    ## The text view will default to a height which encloses all of
    ## the lines of text.
    ## 
    ## If no initial text content is specified, i.e., you have an
    ## empty tag such as @c{<text/>}, then the text will be sized to
    ## some nonzero default width and height. This helps in debugging
    ## applications, (especially in the case of text views which are
    ## initialized from datapaths) because zero width text fields
    ## would be invisible no matter what their text value was set to
    ## at runtime.
    ## 
    ## Text can be scrolled horizontally and vertically.
    ## 
    ## The API calls are @c{text.setYScroll(n)} and @c{text.setXcroll(n)},
    ## where @c{n <= 0}.
    ## 
    ## This scrolls the text vertically or horizontally by n pixels.
    ## 
    ## Note: If you want to scroll by lines rather than pixels,
    ## multiply by the font height of the text field. This won't
    ## really work for HTML formatted text which has multiple font
    ## size, but it will work for text with a single sized font.
    ## 
    ## If you want to know the total height of the text in a text
    ## field (if you want to know how large to draw a scrollbar, for
    ## example) there are a couple of ways to figure this out: For a
    ## multiline=false text field (i.e., one in which wrapping is not
    ## being done automatically by the system), you must manually
    ## count the number of linebreaks in the text, and then multiply
    ## by the font height.
    ## 
    ## For a multiline=true output text field, the system will compute
    ## a property text.scrollHeight which which you may examine. This
    ## field is not maintained for input text.
    element text {
      viewContent
      & textAttributes
      & (attribute text { xsd:string }
         | htmlText*)
    }
  | 
    ## An editable text field.  See the documentation for the @e{text}
    ## tag for a description of the @a{width} and @a{height} attributes,
    ## and of scrolling.
    element inputtext {
      viewContent
      & textAttributes
      & attribute resizable { boolean }?
      & 
        ## If true, the input text field acts like a password input
        ## field; any text typed in appears as "****" characters in the
        ## current font.
        [ a:defaultValue = "false" ] attribute password { boolean }?
      & (attribute text { xsd:string }
         | text?)
    }
textAttributes =
  
  ## If true, the lines of text are wrapped to fit within the text
  ## width.  (The name @c{multiline} is a misnomer.  Unwrapped text
  ## can be multiple lines if it contains a @c{<br />} or @c{<p>}
  ## element, or a line break within a @c{<pre>} element.
  ## 
  ## This attribute defaults to true if width and height are
  ## explicitly specified.
  ## 
  ## If you set multiline=true, you probably want to explicitly a
  ## width for the text also; if multiline=true and you do not specify
  ## a width, the system will pick an arbitrary width (100 pixels at
  ## the moment).
  ## 
  ## When multiline=true, the text is automatially re-wrapped whenever
  ## the content is modified by calls to @c{setText()}, or whenever the
  ## width of the text view is modified.
  [ a:defaultValue = "false" lza:modifiers = "final" ]
  attribute multiline { boolean }?
  & 
    ## If true, the width of the text field will be recomputed each time
    ## setText() is called, so that the text view is exactly as wide as
    ## the width of the widest line.
    [ a:defaultValue = "false" ] attribute resize { booleanLiteral }?
  & 
    ## If true, the text is selectable
    [ a:defaultValue = "false" ]
    attribute selectable { booleanLiteral }?
  & attribute label { string }?
textContent =
  attribute text { xsd:string }
  | text?
htmlContent =
  attribute text { xsd:string }
  | htmlText?
htmlText =
  (text
   | 
     ## An HTML preformatted text region.  Whitespace and line breaks within
     ## this element are preserved.  This can only occur inside HTML text.
     element pre { htmlText }
   | 
     ## An HTML hypertext link.  This can only occur inside HTML text.
     element a {
       
       ## The link target.
       attribute href { xsd:anyURI }
       & 
         ## The value of this attribute determines where the link target
         ## will be displayed.  The interpretation is the same as in HTML,
         ## where the "current frame" is the frame containing the LZX
         ## application.  The value must be a name beginning with an
         ## alphabetic character, or one of the following:
         ## 
         ## <dl>
         ##     <dt> @c{_blank} </dt>
         ##     <dd>
         ##         The user agent should load the designated
         ## document in a new, unnamed window.
         ##     </dd>
         ##     <dt> @c{_parent} </dt>
         ##     <dd>
         ##         The user agent should load the document into
         ## the full, original window (thus canceling all other
         ## frames). This value is equivalent to @c{_self} if the current
         ## frame has no parent.
         ##     </dd>
         ##     <dt> @c{_self} </dt>
         ##     <dd>
         ##         The user agent should load the document in
         ## the same frame as the element that refers to this target.
         ##     </dd>
         ##     <dt> @c{_top} </dt>
         ##     <dd>
         ##         The user agent should load the document into
         ## the immediate FRAMESET parent of the current frame. This
         ## value is equivalent to @c{_self} if the current frame has no
         ## parent.
         ##     </dd>
         ## </dl>
         attribute target {
           "_blank"
           | "_parent"
           | "_self"
           | "_top"
           | xsd:string { pattern = "[a-zA-Z][a-zA-Z0-9\-_:.]*" }
         }?
       & htmlText
     }
   | 
     ## HTML bold character markup.  This can only occur inside HTML text.
     element b { htmlText }
   | 
     ## A font element within HTML text specifies the font face, size,
     ## and color for text within this element.
     [ lza:name = "HTML font" ]
     element font {
       attribute face { string }?
       & attribute size { sizeLiteral }?
       & attribute color { colorLiteral }?
       & htmlText
     }
   | 
     ## Italic character markup.  This can only occur inside HTML text.
     element i { htmlText }
   | 
     ## An HTML paragraph.  This can only occur inside HTML text.
     element p { htmlText }
   | 
     ## An HTML hard line break.  This can only occur inside HTML text.
     element br { empty }
   | 
     ## HTML underline character markup.  This can only occur inside HTML text.
     element u { htmlText })*
# 
# Assets
#
asset =
  
  ## Defines an audio object, that is compiled into the application.
  ## An audio source defined via @c{<audio name="beep" src="beep.mp3" />}
  ## can be played via the JavaScript command @c{LzAudio.playSound('beep')}.
  ## Also see the @e{resource} tag, which defines an image, movie, or
  ## audio resource that can be played by naming it in an attribute,
  ## without scripting.
  element audio { srcAttribute & idAttribute? & nameAttribute }
asset |= resource
resource =
  
  ## Defines a resource (image, movie, animation, or audio asset)
  ## that can be presented by naming it in the @a{resource}
  ## attribute to a view.  For example, @c{<resource name="image" src="image.jpeg" />}
  ## defines a resource that can be displayed via @c{<view resource="image"/>}.
  element resource {
    nameAttribute
    & (
       ## If src is an identifier name, it must match the name of a resource
       ## that has been defined by the @c{<resource>} tag.  If it is a URL, it
       ## refers to a resource that is requested when the application is run.
       ## Otherwise it should be a pathname, and must name a resource file
       ## that is compiled into the application.
       srcAttribute
       | 
         ## This is a frame of a multi-frame resource.  A multi-frame
         ## resource contains several images which can be toggled among
         ## by script commands.  For example, 
         ## @c{<resource name="mfr"><frame src="f1.jpg"/><frame src="f2.jpg"/></resource>} 
         ## defines a resource with two frames.
         element frame { nameAttribute? & srcAttribute }*)
  }
# 
# Data
#
datasource =
  element datasource {
    idAttribute?
    & nameAttribute?
    & attribute baseurl { xsd:anyURI }?
    & attribute type { string }?
    & attribute waitcursor { string }?
    & attribute timeout { number }?
    & [
        a:defaultValue = "443"
        lza:deprecated =
          "@since 1.1 Use the dataset secureport attribute instead."
      ]
      attribute port {
        xsd:integer { minInclusive = "0" }
      }?
    & 
      ## A dataset element within a @c{<datasource>} element defines a set
      ## of data that is retrieved from that datasource.  The name
      ## of the dataset can be used in the datapath attribute of
      ## a view.
      [ lza:name = "datasource dataset" ]
      element dataset { objectAttributes & datasetContent }*
    & oninitAttribute?
    & objectElements
  }
connectiondatasource =
  
  ## A connection datasource to receive messages from the persistent connection.
  element connectiondatasource {
    idAttribute?
    & nameAttribute?
    & 
      ## The onconnect script is executed when the application is connected.
      attribute onconnect { script }?
    & attribute oninit { script }?
    & 
      ## The ondata script is executed when the application receives a persistent
      ## connection message.
      attribute ondata { script }?
    & 
      ## The onerror script is executed whenever there's a connection failure.
      attribute onerror { script }?
    & 
      ## The ontimeout script is executed whenever a timeout is encountered with
      ## the persistent connection.
      attribute ontimeout { script }?
    & 
      ## The ondisconnect script is executed whenever the application disconnects.
      attribute ondisconnect { script }?
    & 
      ## The onuserdisconnect script is executed whenever a user disconnects. See
      ## the receiveuserdisconnect attribute.
      attribute onuserdisconnect { script }?
    & 
      ## A dataset element within a @c{<connectiondatasource>} element names a
      ## unique dataset whose content is shared with other clients that define a
      ## dataset with the same name on the same server.
      [ lza:name = "persistent connection dataset" ]
      element dataset { nameAttribute }*
    & method*
  }
agent =
  element agent {
    attribute url { string }
  }
connection =
  
  ## Defines a persistent connection.
  element connection {
    
    ## The interval value in milliseconds that the server will send a message to
    ## the application to ensure the connection is kept alive by the client.
    ## The default value of a heartbeat is 5000 milliseconds.
    attribute heartbeat { xsd:integer }?
    & attribute timeout { number }?
    & 
      ## If true, creates a secure persistent connection through https. Otherwise
      ## the connection uses http.
      attribute secure { booleanLiteral }?
    & 
      ## Connection port.
      attribute secureport { xsd:integer }?
    & 
      ## Tells server to send an onuserdisconnect event every time a user 
      ## disconnects. Default is false.
      [ a:defaultValue = "false" ]
      attribute receiveuserdisconnect { booleanLiteral }?
    & 
      ## Connection group name.
      attribute group { string }?
    & 
      ## Class name of server-side java authenticator
      attribute authenticator { string }?
    & 
      ## Authenticator parameters.
      attribute authparam { string }?
    & 
      ## The onconnect script is executed when the application is connected.
      attribute onconnect { script }?
    & 
      ## The ondata script is executed when the application receives a persistent
      ## connection message.
      attribute ondata { script }?
    & 
      ## The onerror script is executed whenever there's a connection failure.
      attribute onerror { script }?
    & 
      ## The ontimeout script is executed whenever a timeout is encountered with
      ## the persistent connection.
      attribute ontimeout { script }?
    & 
      ## The ondisconnect script is executed whenever the application disconnects.
      attribute ondisconnect { script }?
    & 
      ## The onuserdisconnect script is executed whenever a user disconnects. See
      ## the receiveuserdisconnect attribute.
      attribute onuserdisconnect { script }?
    & agent*
    & method*
  }
dataset =
  
  ## A dataset element within a @c{<canvas>} or @c{<library>} element defines a
  ## local dataset.  The name of the dataset can be used in the datapath
  ## attribute of a view.  If the src attribute is a URL, the value of
  ## the dataset is the XML data that a request to the URL named by the
  ## src attribute returns when the application is run.  If the src
  ## attribute is a pathname, the value of the dataset is the content of
  ## the XML file that the pathname refers to, and is compiled into the
  ## application.  If the src attribute is not present, the value of the
  ## dataset is the content of the @c{<dataset>} element.
  [ lza:name = "top-level dataset" ]
  element dataset { nameAttribute & (datasetContent | anyXML) }
datasetContent =
  
  ## If true, enable a response to be encoded via the clients Accept-Encoding
  ## HTTP header.  This allows the server to gzip the response.
  [ lza:since = "1.1" lza:defaultValue = "false" ]
  attribute acceptencodings { boolean }?
  & 
    ## If this is a URL, it defines a request for an XML datasource that
    ## is initiated when the dataset's content is requested.
    ## If this is a pathname, it specifies an XML file whose content
    ## is compiled into the application as the value of the dataset.
    attribute src { xsd:anyURI | constraint }?
  & [ lza:deprecated = "@since 1.1 Use the request attribute instead." ]
    attribute autorequest { boolean }?
  & 
    ## Request this dataset when the app starts.
    [ lza:since = "1.1" lza:defaultValue = "false" ]
    attribute request { boolean }?
  & 
    ## If true, the client should ensure that each request is made,
    ## rather than just making and reporting the last request.
    [ lza:since = "1.1" lza:defaultValue = "false" ]
    attribute queuerequests { boolean }?
  & 
    ## This string is appended to the request.
    [ lza:since = "1.1" ] attribute querystring { xsd:string }?
  & attribute type { xsd:string }?
  & attribute endpoint { xsd:string }?
  & attribute namespace { xsd:string }?
  & attribute method { xsd:string }?
  & 
    ## specifies whether or not the app-LPS connection is secure
    [ a:defaultValue = "false" ] attribute secure { booleanLiteral }?
  & 
    ## Sets the port number to use to connect to the LPS for a secure
    ## connection.  
    [
      a:defaultValue = "443"
      lza:deprecated =
        "@since 1.1 Use the secureport attribute instead."
    ]
    attribute port {
      xsd:integer { minInclusive = "0" }
    }?
  & 
    ## Sets the port number to use to connect to the LPS for a secure
    ## connection. 
    [ a:defaultValue = "443" lza:since = "1.1" ]
    attribute secureport {
      xsd:integer { minInclusive = "0" }
    }?
  & 
    ## If true, include response headers (This is specific to HTTP datasets).
    [ a:defaultValue = "true" ]
    attribute getresponseheaders { boolean }?
  & 
    ## Enables caching of the data response on both the LPS server
    ## and the client.  There are security issues with enabling this.
    ## You usually want the getresponseheaders attribute to be false when
    ## you set this to true.
    [ a:defaultValue = "false" ] attribute cacheable { boolean }?
  & 
    ## The ondata script is executed when data arrives
    [ lza:since = "1.1" ] attribute ondata { script }?
  & 
    ## The onerror script is executed when an error occurs
    [ lza:since = "1.1" ] attribute onerror { script }?
  & 
    ## The ontimeout script is executed when a request times out
    [ lza:since = "1.1" ] attribute ontimeout { script }?
anyXML =
  mixed {
    element * {
      attribute * { string }*
      & anyXML
    }*
  }
dataptrAttributes =
  attribute ondata { script }?
  & attribute onerror { script }?
  & attribute ontimeout { script }?
  & attribute rerunxpath { boolean }?
  & attribute xpath { string }?
  & 
    ## If you use lazy replication, this controls the spacing between elements.
    [ a:defaultValue = "0" ] attribute spacing { size }?
datapointer =
  element datapointer {
    idAttribute?
    & nameAttribute?
    & dataptrAttributes
    & oninitAttribute?
    & attribute p { expression }?
    & objectElements
  }
datapath =
  element datapath {
    idAttribute?
    & nameAttribute?
    & dataptrAttributes
    & 
      ## If pooling is true, views that are data-bound to this datapath
      ## are recycled if the dataset changes.  Otherwise, views are deleted
      ## when the data nodes they are bound to disappear, and created
      ## when new data nodes match the datapath.
      [ a:since = "1.1" a:defaultValue = "false" ]
      attribute pooling { boolean }?
    & attribute sortpath { string }?
    & attribute sortorder { string }?
    & attribute replication { "normal" | "lazy" }?
    & attribute p { expression }?
    & oninitAttribute?
    & objectElements
  }
datapathChildren = datapath | datapointer*
# 
# Fonts
#
font =
  
  ## A font element within a @c{<canvas>} or @c{<library>} defines a font,
  ## which can be referenced by the font attribute of a view, or by
  ## the @a{face} attribute of the @e{font} tag within HTML markup.  A
  ## font element can define a single font face or style, by using the
  ## @a{src} attribute to refer to a TrueType(tm) font that is
  ## included in the application.  For example @c{<font name="MyFont"
  ## src="myfont.ttf"/>} defines a font whose data is read from the
  ## TrueType @c{myfont.ttf} file, and that can be referred to as
  ## "MyFont" in the application source: @c{<text font="MyFont">some
  ## text in MyFont</text>}.
  ## 
  ## A font element can also define a font family, which contains a
  ## set of nested font elements which each define a font face or
  ## style.  For example, @c{<font name="MyFont"><face
  ## src="myfont.ttf"/> <face style="bold" src="myfontB.ttf"/><face
  ## style="italic" src="myfontI.ttf"/></font>} defines a font with
  ## three faces, plain, bold, and italic, which can be used as in
  ## @c{<text font="MyFont" fontstyle="bold">bold</text>}, or @c{<text
  ## font="MyFont">plain <b>bold</b> and <i>italic</i></text>}.  (The
  ## font in this example is missing a bold italic face.)
  element font {
    nameAttribute
    & ((srcAttribute & styleAttribute? & faceElement*) | faceElement+)
  }
faceElement =
  
  ## Defines a font face or style within the font family that the
  ## outer element defines.
  element face { styleAttribute? & srcAttribute }
styleAttribute =
  
  ## Corresponds to the fontstyle attribute of a view.
  attribute style {
    "bold" | "italic" | "bold italic" | "italic bold" | "plain"
  }
# TBD: actually, a list of "bold" or "italic"

# 
# Class system
#
objectElements =
  method*
  & attributeElement*
  & state*
  & node*
  & animator*
  & animatorgroup*
attributeElement =
  element attribute {
    
    ## The name of the attribute.
    [ lza:modifiers = "final" ] attribute name { token }
    & ((
        ## The initial value of the attribute.  The type of this value
        ## is specified by the value of the type attribute; if that
        ## attribute is not present, it's the type of this attribute
        ## in this element's tag.  The attribute is given this value
        ## when the element is created.
        attribute value { string }?
        & [ lza:since = "1.1" ]
          (
           ## When the initial value expression is to be
           ## evaluated.  One of:
           ## <dl>
           ##   <dt>@c{immediately}</dt>
           ##   <dd>evaluate when the enclosing element is defined
           ##       (must be a constant)</dd>
           ##   <dt>@c{once}</dt>
           ##   <dd>evaluate when the enclosing element is
           ##       initialized</dd>
           ##   <dt>@c{always}</dt>
           ##   <dd>update whenever the value of the expression
           ##       changes</dd>
           ## </dl>
           ## The default is @c{when="immediately"}.
           ## 
           ## The setting for @c{when} can be overridden
           ## when assigning a value to an attribute by using the
           ## syntax <code><var>attribute
           ## name</var>=$<var>when
           ## value</var>{<var>expression</var>}</code>.  The
           ## default for
           ## <var>when value</var> is @c{always}, for
           ## example: <code>&lt;view
           ## title="$once{computeTitle()}" /&gt;</code> sets the
           ## title of the view to a computed value and
           ## <code>&lt;view title="${parent.subtitle}" \&gt;</code>
           ## will cause the title of the view to track
           ## @c{parent.subtitle}.
           ##
           [ a:defaultValue = "immediately" ]
           attribute when { "immediately" | "once" | "always" })?)
       | 
         ## As an alternative to the value attribute, an expression
         ## may be supplied in the init attribute.  The attribute is
         ## given the value of the expression when the element
         ## is initialized.
         [
           lza:deprecated =
             "@since 1.1 Use value with when='once' instead."
         ]
         attribute init { expression }
       | 
         ## As an alternative to the value attribute, an expression may be
         ## supplied in the constraint attribute.  The attribute will
         ## be constrained to the value of the expression at all
         ## times.
         [
           lza:deprecated =
             "@since 1.1 Use value with when='always' instead."
         ]
         attribute constraint { expression })?
    & 
      ## The type of the attribute.  This determines how the value is
      ## parsed.  Attributes of type string are automatically quoted
      ## if when="immediate", for any other value of when, a literal
      ## string would have to be quoted to be used as a value.
      [ a:defaultValue = "expression" lza:modifiers = "final" ]
      attribute type {
        "boolean"
        | "color"
        | "expression"
        | "number"
        | "size"
        | "string"
        | "text"
        | "html"
      }?
    & 
      ## True if this is a required attribute.
      [ a:defaultValue = "false" ]
      attribute required { booleanLiteral }?
    & (
       ## Code that is executed when setAttribute is used to set the value
       ## of this attribute.  This code is executed within a context in
       ## which the variable with this attribute's name is
       ## bound to the value passed to setAttribute.
       [ lza:since = "1.1" ] attribute setter { script }
       | 
         ## Code that is executed when setAttribute is used to set the value
         ## of this attribute.  This code is executed within a context in
         ## which the variable with this attribute's name is
         ## bound to the value passed to setAttribute.
         [ lza:deprecated = "@since 1.1 Use setter instead." ]
         attribute onset { script })?
  }
class =
  
  ## Defines a new XML tag name, that can be used in the remainder of
  ## the application source.  An element whose name is this tag name
  ## will inherit the attributes and content of this definition.
  ## 
  ## For example, @c{<class name="mywindow" extends="window" layout="y" title="My Class"><text>my class</text></class>} defines a new tag named @c{mywindow}.  This tag can be used anywhere that @e{window} is used.  @c{<mywindow x="10"><button>Click</button></mywindow>} is equivalent to @c{<window layout="y" title="My Class"><text>my class</text><button>Click</button></window>}.
  ## 
  ## Class definitions must precede view definitions that use the name
  ## of the class.  An application can use a tag that is defined in a
  ## library, if the library is included previous to the point where
  ## the tag is used.
  element class {
    
    ## The name of a new tag that this element defines.
    [ lza:modifiers = "final" ] attribute name { token }
    & 
      ## The name of the tag that this tag extends.
      [ a:defaultValue = "view" lza:modifiers = "final" ]
      attribute extends { token }?
    & # Any attribute can occur, depending on superclass.
      # We need to handle this in a preprocessing step.
      attribute * - (name | extends) { string }*
    & viewContentElements
  }
method =
  element method {
    (nameAttribute
     | (nameAttribute?
        & 
          ## The name of the event that this method is invoked in response to.
          attribute event { string }
        & 
          ## If this attribute is present, it the method is attached to the
          ## object that this attribute names, instead of to the object
          ## that contains the @e{method} definition.
          [ a:defaultValue = "this" ]
          attribute reference { reference }?))
    & 
      ## The parameter names of this method.  The value of this attribute
      ## is a comma-separated list of JavaScript identifiers.
      [ a:defaultValue = "" lza:modifiers = "final" ]
      attribute args { string }?
    & text
  }
state =
  
  ## The state element is declared with the apply, onapply, and onremove attributes,
  ## and the view attributes.  apply, onapply, and onremove control the behavior
  ## of the state itself.  Any other attributes and children are applied to the
  ## state's parent, when the state is applied.
  ## 
  ## Note: If the state is a child of an element that is not a view, such as a
  ## layout or animator, then the view attributes may not make sense.  It is
  ## possible to attach an attribute that applies to one of these other elements
  ## to a state, by using the @c{<attribute>} element.
  element state {
    viewContent
    & attribute apply { boolean }?
    & 
      ## If pooling is true, views that are created by the state are not
      ## destroyed when the state is removed -- instead they just act
      ## as if they were by sending the onremovesubview event and setting
      ## their visibility to false.
      [ a:since = "1.1" a:defaultValue = "false" ]
      attribute pooling { boolean }?
    & 
      ## Script that is executed when the state is applied to its parent.
      attribute onapply { script }?
    & 
      ## Script that is executed when the state is removed from its parent.
      attribute onremove { script }?
  }
node =
  element node {
    objectAttributes
    & objectElements
    & 
      ## Instructions to this element's container about where it should go
      ## within the the container's internal hierarchy.
      ## Defaults to the container itself.
      [ lza:modifiers = "final" ] attribute placement { string }?
    & datapathChildren
  }
layout =
  
  ## A layout arranges the views within the element that it is
  ## attached to.  For example, the layout in
  ## @c{<view><text>A</text><text>B</text><simplelayout
  ## axis="y"/></view>} is necessary to keep the A and B text views
  ## from being positioned on top of each other.  As an alternative to
  ## the layout element, a view may specify a @a{layout} attribute.
  ## For example, the previous example is equivalent to @c{<view
  ## layout="axis: y"><text>A</text><text>B</text></view>}.
  element layout {
    oninitAttribute?
    & idAttribute?
    & nameAttribute?
    & attribute locked { booleanLiteral }?
    & [ lza:modifiers = "final" ] attribute placement { string }?
    & objectElements
  }
# 
# Application Configuration
#
splash =
  element splash {
    
    ## If true, the splash views remain on the canvas after the
    ## preload is complete.
    [ a:defaultValue = "false" ]
    attribute persistent { booleanLiteral }?
    & [ lza:name = "splash view" ]
      element view {
        
        ## This defines both a resource with this name, and a view.
        attribute name { token }?
        & 
          ## This must be a pathname.  If the target contains text, the
          ## text should be converted to outlines.
          attribute resource { xsd:anyURI }
        & 
          ## If this attribute is present, the resource is synchronized
          ## to loading progress.  Its value should be either a number
          ## between 0.0 and 1.0, or a percentage between 0% and 100%
          ## (inclusive).  If the resource is a multiframe resource, the
          ## value is the proportion of the frames to play during the
          ## preload phase of application load; the remainder is played
          ## during the initialization phase.
          attribute ratio { xsd:string }?
        & 
          ## x position of this view relative to the canvas
          [ a:defaultValue = "0" ] attribute x { numberLiteral }?
        & 
          ## y position of this view relative to the canvas
          [ a:defaultValue = "0" ] attribute y { numberLiteral }?
        & 
          ## If true, this view is centered within the canvas.  This
          ## overrides the @a{x} and @a{y} attributes.
          [ a:defaultValue = "false" ]
          attribute center { booleanLiteral }?
      }*
  }
scriptElement =
  
  ## This element contains JavaScript code that is executed when the
  ## application is loaded.  If the @a{src} attribute is present, it
  ## names a JavaScript file whose contents are compiled into the
  ## application.
  element script {
    idAttribute?
    & (
       ## URI for an external script
       attribute src { xsd:anyURI }
       | text?)
  }
preloadresource =
  element preloadresource {
    attribute name { token }?
    & attribute ratio { string }?
    & attribute synctoload { booleanLiteral }
    & attribute hideafterinit { booleanLiteral }
    & attribute center { booleanLiteral }
    & attribute synchronized { booleanLiteral }?
    & attribute lastframe { numberLiteral }?
    & attribute resource { string }?
    & attribute resourcename { string }?
    & viewAttributes
  }