SKY MODULE
<import src="sky:core" as="sky"/>
<!--
 ! this module provides trivial vertical block layout
 ! no margins, padding, borders, etc
 !-->
<script>
 module.exports.BlockLayoutManager = class BlockLayoutManager extends sky.LayoutManager {
   function layout(width, height) {
     this.markAsLaidOut();
     if (width == null)
       width = this.getIntrinsicWidth().value;
     let autoHeight = false;
     if (height == null) {
       height = 0;
       autoHeight = true;
     }
     this.assumeDimensions(width, height);
     let children = this.walkChildren();
     let loop = children.next();
     let y = 0;
     while (!loop.done) {
       let child = loop.value;
       if (child.needsLayout || child.descendantNeedsLayout) {
         let dims = child.layoutManager.layout(width, null);
         this.setChildSize(child, dims.width, dims.height);
       }
       this.setChildPosition(child, 0, y);
       y += child.height;
       loop = children.next();
     }
     if (autoHeight)
       height = y;
     return {
       width: width,
       height: height,
     }
   }
   function getIntrinsicWidth() {
     let width = this.node.getProperty('width');
     if (typeof width != 'number') {
       // e.g. width: auto
       width = 0;
       let children = this.walkChildren();
       let loop = children.next();
       while (!loop.done) {
         let child = loop.value;
         let childWidth = child.layoutManager.getIntrinsicWidth();
         if (width < childWidth.value)
           width = childWidth.value;
         loop = children.next();
       }
     }
     return super(width); // applies and provides our own min-width/max-width rules
   }
   function getIntrinsicHeight() {
     let height = this.node.getProperty('height');
     if (typeof height != 'number') {
       // e.g. height: auto
       height = 0;
       let children = this.walkChildren();
       let loop = children.next();
       while (!loop.done) {
         let child = loop.value;
         let childHeight = child.layoutManager.getIntrinsicHeight();
         if (height < childHeight.value)
           height = childHeight.value;
         loop = children.next();
       }
     }
     return super(height); // applies and provides our own min-height/max-height rules
   }
 }
 sky.registerLayoutManager('block', module.exports.BlockLayoutManager);
</script>