Merge pull request #185 from rigdern/rigdern/spec-conformance

Alter layout engine to conform closer to W3C spec

README.md

@@ -92,10 +92,19 @@ borderWidth, borderLeftWidth, borderRightWidth, borderTopWidth, borderBottomWidt
 flexDirection | 'column', 'row'
 justifyContent | 'flex-start', 'center', 'flex-end', 'space-between', 'space-around'
 alignItems, alignSelf | 'flex-start', 'center', 'flex-end', 'stretch'
-flex | positive number
+flex | number
 flexWrap | 'wrap', 'nowrap'
 position | 'relative', 'absolute'
+overflow | 'visible', 'hidden'
 
+- Rather than allowing arbitrary combinations of `flex-grow`, `flex-shrink`, and `flex-basis` the implementation only supports a few common combinations expressed as a single number using the `flex` attribute:
+
+  css-layout `flex` value | W3C `flex` short-hand equivalent
+  ---|---
+  n (where n > 0) | n 0 0
+  0 | 0 0 auto
+  -1 | 0 1 auto
+  
 - `inherit` value is not implemented because it's a way to disambiguate between multiple colliding rules. This should be done in a pre-processing step, not in the actual layout algorithm.
 
 
@@ -118,6 +127,7 @@ div, span {
   border: 0 solid black;
   margin: 0;
   padding: 0;
+  min-width: 0;
 }
 ```
 

TestResult.xml

@@ -1,9 +0,0 @@
-<?xml version="1.0" encoding="utf-8" standalone="no"?>
-<!--This file represents the results of running a test suite-->
-<test-results name="src/csharp/Facebook.CSSLayout.Tests/bin/Release/Facebook.CSSLayout.Tests.dll" total="0" failures="0" not-run="0" date="2016-04-01" time="11:01:04">
-  <environment nunit-version="2.4.8.0" clr-version="4.0.30319.17020" os-version="Unix 15.4.0.0" platform="Unix" cwd="/Users/emilsj/css-layout" machine-name="emilsj-pro" user="emilsj" user-domain="emilsj-pro" />
-  <culture-info current-culture="en-US" current-uiculture="en-US" />
-  <test-suite name="src/csharp/Facebook.CSSLayout.Tests/bin/Release/Facebook.CSSLayout.Tests.dll" success="True" time="0.001" asserts="0">
-    <results />
-  </test-suite>
-</test-results>

src/CSharpTranspiler.js

@@ -9,11 +9,18 @@
 
 function __transpileToCSharpCommon(code) {
   return code
+    .replace(/'abs-layout'/g, '"abs-layout"')
+    .replace(/'abs-measure'/g, '"abs-measure"')
+    .replace(/'flex'/g, '"flex"')
+    .replace(/'measure'/g, '"measure"')
+    .replace(/'stretch'/g, '"stretch"')
+    .replace(/undefined/g, 'null')
     .replace(/CSS_UNDEFINED/g, 'CSSConstants.UNDEFINED')
     .replace(/CSS_JUSTIFY_/g, 'CSSJustify.')
     .replace(/CSS_MEASURE_MODE_/g, 'CSSMeasureMode.')
     .replace(/CSS_ALIGN_/g, 'CSSAlign.')
     .replace(/CSS_POSITION_/g, 'CSSPositionType.')
+    .replace(/CSS_OVERFLOW_/g, 'CSSOverflow.')
     .replace(/css_flex_direction_t/g, 'CSSFlexDirection')
     .replace(/css_direction_t/g, 'CSSDirection')
     .replace(/css_align_t/g, 'CSSAlign')
@@ -21,6 +28,10 @@ function __transpileToCSharpCommon(code) {
     .replace(/css_measure_mode_t/g, 'CSSMeasureMode')
     .replace(/css_dim_t/g, 'MeasureOutput')
     .replace(/bool/g, 'boolean')
+    .replace(/style\[CSS_LEFT/g, 'style.position[POSITION_LEFT')
+    .replace(/style\[CSS_TOP/g, 'style.position[POSITION_TOP')
+    .replace(/style\[CSS_RIGHT/g, 'style.position[POSITION_RIGHT')
+    .replace(/style\[CSS_BOTTOM/g, 'style.position[POSITION_BOTTOM')
     .replace(/style\[dim/g, 'style.dimensions[dim')
     .replace(/(style|layout)\.width/g, '$1.dimensions[DIMENSION_WIDTH]')
     .replace(/(style|layout)\.height/g, '$1.dimensions[DIMENSION_HEIGHT]')
@@ -28,22 +39,24 @@ function __transpileToCSharpCommon(code) {
     .replace(/layout\[pos/g, 'layout.position[pos')
     .replace(/layout\[leading/g, 'layout.position[leading')
     .replace(/layout\[trailing/g, 'layout.position[trailing')
+    .replace(/layout\[measuredDim/g, 'layout.measuredDimensions[dim')
+    .replace(/layout\.measuredWidth/g, 'layout.measuredDimensions[DIMENSION_WIDTH]')
+    .replace(/layout\.measuredHeight/g, 'layout.measuredDimensions[DIMENSION_HEIGHT]')
     .replace(/getPositionType\((.+?)\)/g, '$1.style.positionType')
     .replace(/getJustifyContent\((.+?)\)/g, '$1.style.justifyContent')
     .replace(/getAlignContent\((.+?)\)/g, '$1.style.alignContent')
     .replace(/isPosDefined\((.+?),\s*(.+?)\)/g, '!isUndefined\($1.style.position[$2]\)')
-    .replace(/isStyleDimDefined\((.+?),\s*(.+?)\)/g, '\(!isUndefined\($1.style.dimensions[dim[$2]]\) && $1.style.dimensions[dim[$2]] >= 0.0\)')
-    .replace(/isLayoutDimDefined\((.+?),\s*(.+?)\)/g, '\(!isUndefined\($1.layout.dimensions[dim[$2]]\) && $1.layout.dimensions[dim[$2]] >= 0.0\)')
+    .replace(/isStyleDimDefined\((.+?),\s*(.+?)\)/g, '($1.style.dimensions[dim[$2]] >= 0.0)')
+    .replace(/isLayoutDimDefined\((.+?),\s*(.+?)\)/g, '($1.layout.measuredDimensions[dim[$2]] >= 0.0)')
     .replace(/getPosition\((.+?),\s*(.+?)\)/g, '\(isUndefined\($1.style.position[$2]\) ?  0 : $1.style.position[$2]\)')
-    .replace(/setTrailingPosition\((.+?),\s*(.+?),\s*(.+?)\)/g, '$2.layout.position[trailing[$3]] = $1.layout.dimensions[dim[$3]] - $2.layout.dimensions[dim[$3]] - $2.layout.position[pos[$3]]')
-    .replace(/isFlex\((.+?)\)/g, '\($1.style.positionType == CSSPositionType.RELATIVE && $1.style.flex > 0\)')
+    .replace(/setTrailingPosition\((.+?),\s*(.+?),\s*(.+?)\)/g, '$2.layout.position[trailing[$3]] = $1.layout.measuredDimensions[dim[$3]] - ($2.style.positionType == CSSPositionType.Absolute ? 0 : $2.layout.measuredDimensions[dim[$3]]) - $2.layout.position[pos[$3]]')
+    .replace(/isFlex\((.+?)\)/g, '\($1.style.positionType == CSSPositionType.RELATIVE && $1.style.flex != 0\)')
     .replace(/isFlexWrap\((.+?)\)/g, '\($1.style.flexWrap == CSSWrap.WRAP\)')
     .replace(/getPaddingAndBorderAxis\((.+?),\s*(.+?)\)/g, '\(getLeadingPaddingAndBorder($1, $2) + getTrailingPaddingAndBorder($1, $2)\)')
-    .replace(/getBorderAxis\((.+?),\s*(.+?)\)/g, '\(getLeadingBorder($1, $2) + getTrailingBorder($1, $2)\)')
     .replace(/getMarginAxis\((.+?),\s*(.+?)\)/g, '\(getLeadingMargin($1, $2) + getTrailingMargin($1, $2)\)')
     .replace(/getLeadingPaddingAndBorder\((.+?),\s*(.+?)\)/g, '\(getLeadingPadding($1, $2) + getLeadingBorder($1, $2)\)')
     .replace(/getTrailingPaddingAndBorder\((.+?),\s*(.+?)\)/g, '\(getTrailingPadding($1, $2) + getTrailingBorder($1, $2)\)')
-    .replace(/getDimWithMargin\((.+?),\s*(.+?)\)/g, '\($1.layout.dimensions[dim[$2]] + getLeadingMargin($1, $2) + getTrailingMargin($1, $2)\)')
+    .replace(/getDimWithMargin\((.+?),\s*(.+?)\)/g, '\($1.layout.measuredDimensions[dim[$2]] + getLeadingMargin($1, $2) + getTrailingMargin($1, $2)\)')
     .replace(/getLeadingMargin\((.+?),\s*(.+?)\)/g, '$1.style.margin.getWithFallback(leadingSpacing[$2], leading[$2])')
     .replace(/getTrailingMargin\((.+?),\s*(.+?)\)/g, '$1.style.margin.getWithFallback(trailingSpacing[$2], trailing[$2])')
     .replace(/getLeadingPadding\((.+?),\s*(.+?)\)/g, '$1.style.padding.getWithFallback(leadingSpacing[$2], leading[$2])')
@@ -51,14 +64,18 @@ function __transpileToCSharpCommon(code) {
     .replace(/getLeadingBorder\((.+?),\s*(.+?)\)/g, '$1.style.border.getWithFallback(leadingSpacing[$2], leading[$2])')
     .replace(/getTrailingBorder\((.+?),\s*(.+?)\)/g, '$1.style.border.getWithFallback(trailingSpacing[$2], trailing[$2])')
     .replace(/isRowDirection\((.+?)\)/g, '\($1 == CSS_FLEX_DIRECTION_ROW || $1 == CSS_FLEX_DIRECTION_ROW_REVERSE\)')
+    .replace(/assert\((.+?),\s*'(.+?)'\)/g, 'Assertions.assertCondition($1, "$2")')
     .replace(/isUndefined\((.+?)\)/g, 'float.IsNaN\($1\)')
+    .replace(/getOverflow\((.+?)\)/g, '$1.style.overflow')
+    .replace(/layoutNodeInternal\((.+?)\)/g, 'layoutNodeInternal(layoutContext, $1)')
+    .replace(/style\.position\[CSS_/g, 'style.position[POSITION_')
     .replace(/\/\*\(c\)!([^*]+)\*\//g, '')
     .replace(/var\/\*\(java\)!([^*]+)\*\//g, '$1')
     .replace(/\/\*\(java\)!([^*]+)\*\//g, '$1')
 
     // additional case conversions
 
-    .replace(/(CSSConstants|CSSWrap|CSSJustify|CSSMeasureMode|CSSAlign|CSSPositionType)\.([_A-Z]+)/g,
+    .replace(/(CSSConstants|CSSWrap|CSSJustify|CSSMeasureMode|CSSAlign|CSSPositionType|CSSOverflow)\.([_A-Z]+)/g,
         function(str, match1, match2) {
           return match1 + '.' + constantToPascalCase(match2);
         });
@@ -139,12 +156,12 @@ var CSharpTranspiler = {
   transpileLayoutEngine: function(code) {
     return indent(
       __transpileToCSharpCommon(code)
-        .replace(/function\s+layoutNode.*/, '')
         .replace('node.style.measure', 'node.measure')
         .replace(/\.children\.length/g, '.getChildCount()')
         .replace(/node.children\[i\]/g, 'node.getChildAt(i)')
-        .replace(/node.children\[ii\]/g, 'node.getChildAt(ii)')
+        .replace(/node.children\[j\]/g, 'node.getChildAt(j)')
         .replace(/fmaxf/g, 'Math.Max')
+        .replace(/fminf/g, 'Math.Min')
         .replace(/\/\*\([^\/]+\*\/\n/g, '') // remove comments for other languages
         .replace(/var\/\*([^\/]+)\*\//g, '$1')
         .replace(/ === /g, ' == ')

src/JavaTranspiler.js

@@ -9,11 +9,18 @@
 
 function __transpileToJavaCommon(code) {
   return code
+    .replace(/'abs-layout'/g, '"abs-layout"')
+    .replace(/'abs-measure'/g, '"abs-measure"')
+    .replace(/'flex'/g, '"flex"')
+    .replace(/'measure'/g, '"measure"')
+    .replace(/'stretch'/g, '"stretch"')
+    .replace(/undefined/g, 'null')
     .replace(/CSS_UNDEFINED/g, 'CSSConstants.UNDEFINED')
     .replace(/CSS_JUSTIFY_/g, 'CSSJustify.')
     .replace(/CSS_MEASURE_MODE_/g, 'CSSMeasureMode.')
     .replace(/CSS_ALIGN_/g, 'CSSAlign.')
     .replace(/CSS_POSITION_/g, 'CSSPositionType.')
+    .replace(/CSS_OVERFLOW_/g, 'CSSOverflow.')
     .replace(/css_flex_direction_t/g, 'CSSFlexDirection')
     .replace(/css_direction_t/g, 'CSSDirection')
     .replace(/css_align_t/g, 'CSSAlign')
@@ -21,6 +28,10 @@ function __transpileToJavaCommon(code) {
     .replace(/css_measure_mode_t/g, 'CSSMeasureMode')
     .replace(/css_dim_t/g, 'MeasureOutput')
     .replace(/bool/g, 'boolean')
+    .replace(/style\[CSS_LEFT/g, 'style.position[POSITION_LEFT')
+    .replace(/style\[CSS_TOP/g, 'style.position[POSITION_TOP')
+    .replace(/style\[CSS_RIGHT/g, 'style.position[POSITION_RIGHT')
+    .replace(/style\[CSS_BOTTOM/g, 'style.position[POSITION_BOTTOM')
     .replace(/style\[dim/g, 'style.dimensions[dim')
     .replace(/(style|layout)\.width/g, '$1.dimensions[DIMENSION_WIDTH]')
     .replace(/(style|layout)\.height/g, '$1.dimensions[DIMENSION_HEIGHT]')
@@ -28,22 +39,24 @@ function __transpileToJavaCommon(code) {
     .replace(/layout\[pos/g, 'layout.position[pos')
     .replace(/layout\[leading/g, 'layout.position[leading')
     .replace(/layout\[trailing/g, 'layout.position[trailing')
+    .replace(/layout\[measuredDim/g, 'layout.measuredDimensions[dim')
+    .replace(/layout\.measuredWidth/g, 'layout.measuredDimensions[DIMENSION_WIDTH]')
+    .replace(/layout\.measuredHeight/g, 'layout.measuredDimensions[DIMENSION_HEIGHT]')
     .replace(/getPositionType\((.+?)\)/g, '$1.style.positionType')
     .replace(/getJustifyContent\((.+?)\)/g, '$1.style.justifyContent')
     .replace(/getAlignContent\((.+?)\)/g, '$1.style.alignContent')
     .replace(/isPosDefined\((.+?),\s*(.+?)\)/g, '!isUndefined\($1.style.position[$2]\)')
-    .replace(/isStyleDimDefined\((.+?),\s*(.+?)\)/g, '\(!isUndefined\($1.style.dimensions[dim[$2]]\) && $1.style.dimensions[dim[$2]] >= 0.0\)')
-    .replace(/isLayoutDimDefined\((.+?),\s*(.+?)\)/g, '\(!isUndefined\($1.layout.dimensions[dim[$2]]\) && $1.layout.dimensions[dim[$2]] >= 0.0\)')
+    .replace(/isStyleDimDefined\((.+?),\s*(.+?)\)/g, '($1.style.dimensions[dim[$2]] >= 0.0)')
+    .replace(/isLayoutDimDefined\((.+?),\s*(.+?)\)/g, '($1.layout.measuredDimensions[dim[$2]] >= 0.0)')
     .replace(/getPosition\((.+?),\s*(.+?)\)/g, '\(isUndefined\($1.style.position[$2]\) ?  0 : $1.style.position[$2]\)')
-    .replace(/setTrailingPosition\((.+?),\s*(.+?),\s*(.+?)\)/g, '$2.layout.position[trailing[$3]] = $1.layout.dimensions[dim[$3]] - $2.layout.dimensions[dim[$3]] - $2.layout.position[pos[$3]]')
-    .replace(/isFlex\((.+?)\)/g, '\($1.style.positionType == CSSPositionType.RELATIVE && $1.style.flex > 0\)')
+    .replace(/setTrailingPosition\((.+?),\s*(.+?),\s*(.+?)\)/g, '$2.layout.position[trailing[$3]] = $1.layout.measuredDimensions[dim[$3]] - ($2.style.positionType == CSSPositionType.ABSOLUTE ? 0 : $2.layout.measuredDimensions[dim[$3]]) - $2.layout.position[pos[$3]]')
+    .replace(/isFlex\((.+?)\)/g, '\($1.style.positionType == CSSPositionType.RELATIVE && $1.style.flex != 0\)')
     .replace(/isFlexWrap\((.+?)\)/g, '\($1.style.flexWrap == CSSWrap.WRAP\)')
     .replace(/getPaddingAndBorderAxis\((.+?),\s*(.+?)\)/g, '\(getLeadingPaddingAndBorder($1, $2) + getTrailingPaddingAndBorder($1, $2)\)')
-    .replace(/getBorderAxis\((.+?),\s*(.+?)\)/g, '\(getLeadingBorder($1, $2) + getTrailingBorder($1, $2)\)')
     .replace(/getMarginAxis\((.+?),\s*(.+?)\)/g, '\(getLeadingMargin($1, $2) + getTrailingMargin($1, $2)\)')
     .replace(/getLeadingPaddingAndBorder\((.+?),\s*(.+?)\)/g, '\(getLeadingPadding($1, $2) + getLeadingBorder($1, $2)\)')
     .replace(/getTrailingPaddingAndBorder\((.+?),\s*(.+?)\)/g, '\(getTrailingPadding($1, $2) + getTrailingBorder($1, $2)\)')
-    .replace(/getDimWithMargin\((.+?),\s*(.+?)\)/g, '\($1.layout.dimensions[dim[$2]] + getLeadingMargin($1, $2) + getTrailingMargin($1, $2)\)')
+    .replace(/getDimWithMargin\((.+?),\s*(.+?)\)/g, '\($1.layout.measuredDimensions[dim[$2]] + getLeadingMargin($1, $2) + getTrailingMargin($1, $2)\)')
     .replace(/getLeadingMargin\((.+?),\s*(.+?)\)/g, '$1.style.margin.getWithFallback(leadingSpacing[$2], leading[$2])')
     .replace(/getTrailingMargin\((.+?),\s*(.+?)\)/g, '$1.style.margin.getWithFallback(trailingSpacing[$2], trailing[$2])')
     .replace(/getLeadingPadding\((.+?),\s*(.+?)\)/g, '$1.style.padding.getWithFallback(leadingSpacing[$2], leading[$2])')
@@ -51,7 +64,11 @@ function __transpileToJavaCommon(code) {
     .replace(/getLeadingBorder\((.+?),\s*(.+?)\)/g, '$1.style.border.getWithFallback(leadingSpacing[$2], leading[$2])')
     .replace(/getTrailingBorder\((.+?),\s*(.+?)\)/g, '$1.style.border.getWithFallback(trailingSpacing[$2], trailing[$2])')
     .replace(/isRowDirection\((.+?)\)/g, '\($1 == CSS_FLEX_DIRECTION_ROW || $1 == CSS_FLEX_DIRECTION_ROW_REVERSE\)')
+    .replace(/assert\((.+?),\s*'(.+?)'\)/g, 'Assertions.assertCondition($1, "$2")')
     .replace(/isUndefined\((.+?)\)/g, 'Float.isNaN\($1\)')
+    .replace(/getOverflow\((.+?)\)/g, '$1.style.overflow')
+    .replace(/layoutNodeInternal\((.+?)\)/g, 'layoutNodeInternal(layoutContext, $1)')
+    .replace(/style\.position\[CSS_/g, 'style.position[POSITION_')
     .replace(/\/\*\(c\)!([^*]+)\*\//g, '')
     .replace(/var\/\*\(java\)!([^*]+)\*\//g, '$1')
     .replace(/\/\*\(java\)!([^*]+)\*\//g, '$1');
@@ -118,12 +135,12 @@ var JavaTranspiler = {
   transpileLayoutEngine: function(code) {
     return indent(
       __transpileToJavaCommon(code)
-        .replace(/function\s+layoutNode.*/, '')
         .replace('node.style.measure', 'node.measure')
         .replace(/\.children\.length/g, '.getChildCount()')
         .replace(/node.children\[i\]/g, 'node.getChildAt(i)')
-        .replace(/node.children\[ii\]/g, 'node.getChildAt(ii)')
+        .replace(/node.children\[j\]/g, 'node.getChildAt(j)')
         .replace(/fmaxf/g, 'Math.max')
+        .replace(/fminf/g, 'Math.min')
         .replace(/\/\*\([^\/]+\*\/\n/g, '') // remove comments for other languages
         .replace(/var\/\*([^\/]+)\*\//g, '$1')
         .replace(/ === /g, ' == ')

src/Layout-test-utils.js

@@ -92,6 +92,7 @@ var layoutTestUtils = (function() {
 
           margin: 0;
           padding: 0;
+          min-width: 0;
         }
 
         hack to ignore three hundred px width of the body {}
@@ -115,20 +116,28 @@ var layoutTestUtils = (function() {
   if (typeof computeLayout === 'object') {
     var fillNodes = computeLayout.fillNodes;
     var realComputeLayout = computeLayout.computeLayout;
+    var canUseCachedMeasurement = computeLayout.canUseCachedMeasurement;
   }
 
   function extractNodes(node) {
-    var layout = node.layout;
-    delete node.layout;
+    var keysToCopy = [
+      'width',
+      'height',
+      'left',
+      'top'
+    ];
+    var layout = {};
+    keysToCopy.forEach(function(key) {
+      layout[key] = node.layout[key];
+    });
+    
     if (node.children && node.children.length > 0) {
       layout.children = node.children.map(extractNodes);
     } else {
       delete node.children;
     }
-
-    delete layout.right;
-    delete layout.bottom;
-    delete layout.direction;
+    
+    delete node.layout;
 
     return layout;
   }
@@ -183,13 +192,17 @@ var layoutTestUtils = (function() {
 
   function computeDOMLayout(node) {
     var body = getIframe().contentDocument.body;
-
+    
+    function setStyle(div, name, value) {
+      div.style['-webkit-' + name] = value;
+      div.style['webkit' + capitalizeFirst(name)] = value;
+      div.style[name] = value;
+    }
+    
     function transfer(div, node, name, ext) {
       if (name in node.style) {
         var value = node.style[name] + (ext || '');
-        div.style['-webkit-' + name] = value;
-        div.style['webkit' + capitalizeFirst(name)] = value;
-        div.style[name] = value;
+        setStyle(div, name, value);
       }
     }
 
@@ -202,7 +215,19 @@ var layoutTestUtils = (function() {
       transfer(div, node, type + 'Start' + suffix, 'px');
       transfer(div, node, type + 'End' + suffix, 'px');
     }
-
+    
+    function transferFlex(div, node) {
+      if ('flex' in node.style) {
+        var flex = node.style.flex;
+        var resolvedFlex = (
+          flex < 0 ? '0 1 auto' :
+          flex > 0 ? (flex + ' 0 0') :
+          '0 0 auto'
+        );
+        setStyle(div, 'flex', resolvedFlex);
+      }
+    }
+    
     function renderNode(parent, node) {
       var div = document.createElement('div');
       transfer(div, node, 'width', 'px');
@@ -220,13 +245,14 @@ var layoutTestUtils = (function() {
       transferSpacing(div, node, 'border', 'Width');
       transfer(div, node, 'flexDirection');
       transfer(div, node, 'direction');
-      transfer(div, node, 'flex');
+      transferFlex(div, node);
       transfer(div, node, 'flexWrap');
       transfer(div, node, 'justifyContent');
       transfer(div, node, 'alignSelf');
       transfer(div, node, 'alignItems');
       transfer(div, node, 'alignContent');
       transfer(div, node, 'position');
+      transfer(div, node, 'overflow');
       parent.appendChild(div);
       (node.children || []).forEach(function(child) {
         renderNode(div, child);
@@ -299,6 +325,22 @@ var layoutTestUtils = (function() {
   function testExtractNodes(node, extractedNode) {
     expect(extractNodes(node)).toEqual(extractedNode);
   }
+  
+  function testCanUseCachedMeasurement(canReuse, spec, cacheEntry) {
+    var availableWidth = spec.availableWidth;
+    var availableHeight = spec.availableHeight;
+    var widthMeasureMode = spec.widthMeasureMode;
+    var heightMeasureMode = spec.heightMeasureMode;
+    
+    expect(
+      canUseCachedMeasurement(
+        availableWidth, availableHeight,
+        0, 0,
+        widthMeasureMode, heightMeasureMode,
+        cacheEntry
+      )
+    ).toEqual(canReuse);
+  }
 
   function testNamedLayout(name, layoutA, layoutB) {
     expect(nameLayout(name, layoutA))
@@ -479,6 +521,7 @@ var layoutTestUtils = (function() {
     },
     testFillNodes: testFillNodes,
     testExtractNodes: testExtractNodes,
+    testCanUseCachedMeasurement: testCanUseCachedMeasurement,
     testRandomLayout: function(node) {
       var layout = computeCSSLayout(node);
       var domLayout = computeDOMLayout(node);

src/Layout.h

@@ -44,6 +44,11 @@ typedef enum {
   CSS_JUSTIFY_SPACE_AROUND
 } css_justify_t;
 
+typedef enum {
+  CSS_OVERFLOW_VISIBLE = 0,
+  CSS_OVERFLOW_HIDDEN
+} css_overflow_t;
+
 // Note: auto is only a valid value for alignSelf. It is NOT a valid value for
 // alignItems.
 typedef enum {
@@ -79,7 +84,8 @@ typedef enum {
 typedef enum {
   CSS_MEASURE_MODE_UNDEFINED = 0,
   CSS_MEASURE_MODE_EXACTLY,
-  CSS_MEASURE_MODE_AT_MOST
+  CSS_MEASURE_MODE_AT_MOST,
+  CSS_MEASURE_MODE_COUNT
 } css_measure_mode_t;
 
 typedef enum {
@@ -87,20 +93,40 @@ typedef enum {
   CSS_HEIGHT
 } css_dimension_t;
 
+typedef struct {
+  float available_width;
+  float available_height;
+  css_measure_mode_t width_measure_mode;
+  css_measure_mode_t height_measure_mode;
+
+  float computed_width;
+  float computed_height;
+} css_cached_measurement_t;
+
+enum {
+  // This value was chosen based on empiracle data. Even the most complicated
+  // layouts should not require more than 16 entries to fit within the cache.
+  CSS_MAX_CACHED_RESULT_COUNT = 16
+};
+
 typedef struct {
   float position[4];
   float dimensions[2];
   css_direction_t direction;
 
+  float flex_basis;
+
   // Instead of recomputing the entire layout every single time, we
   // cache some information to break early when nothing changed
   bool should_update;
-  float last_requested_dimensions[2];
-  float last_parent_max_width;
-  float last_parent_max_height;
-  float last_dimensions[2];
-  float last_position[2];
-  css_direction_t last_direction;
+  int generation_count;
+  css_direction_t last_parent_direction;
+
+  int next_cached_measurements_index;
+  css_cached_measurement_t cached_measurements[CSS_MAX_CACHED_RESULT_COUNT];
+  float measured_dimensions[2];
+
+  css_cached_measurement_t cached_layout;
 } css_layout_t;
 
 typedef struct {
@@ -116,6 +142,7 @@ typedef struct {
   css_align_t align_self;
   css_position_type_t position_type;
   css_wrap_type_t flex_wrap;
+  css_overflow_t overflow;
   float flex;
   float margin[6];
   float position[4];
@@ -143,8 +170,7 @@ struct css_node {
   int children_count;
   int line_index;
 
-  css_node_t *next_absolute_child;
-  css_node_t *next_flex_child;
+  css_node_t* next_child;
 
   css_dim_t (*measure)(void *context, float width, css_measure_mode_t widthMode, float height, css_measure_mode_t heightMode);
   void (*print)(void *context);
@@ -166,12 +192,8 @@ typedef enum {
 } css_print_options_t;
 void print_css_node(css_node_t *node, css_print_options_t options);
 
+// Function that computes the layout!
+void layoutNode(css_node_t *node, float availableWidth, float availableHeight, css_direction_t parentDirection);
 bool isUndefined(float value);
 
-// Function that computes the layout!
-void layoutNode(css_node_t *node, float maxWidth, float maxHeight, css_direction_t parentDirection);
-
-// Reset the calculated layout values for a given node. You should call this before `layoutNode`.
-void resetNodeLayout(css_node_t *node);
-
 #endif

src/__tests__/Layout-test.js

@@ -12,6 +12,7 @@ var testLayout = layoutTestUtils.testLayout;
 var testLayoutAgainstDomOnly = layoutTestUtils.testLayoutAgainstDomOnly;
 var testLayoutAgainstExpectedOnly = layoutTestUtils.testLayoutAgainstExpectedOnly;
 var testFillNodes = layoutTestUtils.testFillNodes;
+var testCanUseCachedMeasurement = layoutTestUtils.testCanUseCachedMeasurement;
 var text = layoutTestUtils.text;
 var texts = layoutTestUtils.texts;
 var textSizes = layoutTestUtils.textSizes;
@@ -38,6 +39,152 @@ describe('Javascript Only', function() {
       {layout: {width: 200}},
       {layout: {width: 200}, style: {}, children: []}
     );
+  });  
+  it('should only invoke measure function one time in simple layout', function() {
+    var measureInvocations = 0;
+    function measure(width, widthMode, height, heightMode) {
+      measureInvocations++;
+      return { width: 25, height: 25 };
+    }
+    
+    testLayoutAgainstExpectedOnly(
+      {style: {width: 100, height: 100}, children: [
+        {style: {measure: measure}}
+      ]},
+      {width: 100, height: 100, top: 0, left: 0, children: [
+        {width: 100, height: 25, top: 0, left: 0}
+      ]}
+    );
+    
+    expect(measureInvocations).toEqual(1);
+  });
+});
+
+describe('JavaScript Only: canUseCachedTextMeasurement', function() {
+  var measureModes = ['undefined', 'exactly', 'at-most'];
+  
+  var assertCanReuse = testCanUseCachedMeasurement.bind(null, true);
+  var assertCannotReuse = testCanUseCachedMeasurement.bind(null, false);
+  
+  it('should not reuse when width mode is "exactly" and available width != measurement', function() {
+    measureModes.forEach(function(widthMeasureMode) {
+      measureModes.forEach(function(heightMeasureMode) {
+        var computedWidth = 100;
+        var computedHeight = 200;
+        var availableWidth = widthMeasureMode === 'undefined' ? undefined : computedWidth;
+        var availableHeight = heightMeasureMode === 'undefined' ? undefined : computedHeight;
+        
+        var cacheEntry = {
+          availableWidth: availableWidth, widthMeasureMode: widthMeasureMode, computedWidth: computedWidth,
+          availableHeight: availableHeight, heightMeasureMode: heightMeasureMode, computedHeight: computedHeight
+        };
+        
+        assertCannotReuse(
+          {
+            availableWidth: computedWidth - 1, widthMeasureMode: 'exactly',
+            availableHeight: availableHeight, heightMeasureMode: heightMeasureMode
+          },
+          cacheEntry
+        );
+        
+        assertCannotReuse(
+          {
+            availableWidth: computedWidth + 1, widthMeasureMode: 'exactly',
+            availableHeight: availableHeight, heightMeasureMode: heightMeasureMode
+          },
+          cacheEntry
+        );
+      });
+    });
+  });
+  
+  it('should not reuse when height mode is "exactly" and available height != measurement', function() {
+    measureModes.forEach(function(widthMeasureMode) {
+      measureModes.forEach(function(heightMeasureMode) {
+        var computedWidth = 100;
+        var computedHeight = 200;
+        var availableWidth = widthMeasureMode === 'undefined' ? undefined : computedWidth;
+        var availableHeight = heightMeasureMode === 'undefined' ? undefined : computedHeight;
+        
+        var cacheEntry = {
+          availableWidth: availableWidth, widthMeasureMode: widthMeasureMode, computedWidth: computedWidth,
+          availableHeight: availableHeight, heightMeasureMode: heightMeasureMode, computedHeight: computedHeight
+        };
+        
+        assertCannotReuse(
+          {
+            availableWidth: availableWidth, widthMeasureMode: widthMeasureMode,
+            availableHeight: computedHeight - 1, heightMeasureMode: 'exactly'
+          },
+          cacheEntry
+        );
+        
+        assertCannotReuse(
+          {
+            availableWidth: availableWidth, widthMeasureMode: widthMeasureMode,
+            availableHeight: computedHeight + 1, heightMeasureMode: 'exactly'
+          },
+          cacheEntry
+        );
+      });
+    });
+  });
+  
+  it('should reuse exact matches', function() {
+    measureModes.forEach(function(widthMeasureMode) {
+      measureModes.forEach(function(heightMeasureMode) {
+        var availableWidth = widthMeasureMode === 'undefined' ? undefined : 100;
+        var availableHeight = heightMeasureMode === 'undefined' ? undefined : 200;
+        assertCanReuse(
+          {
+            availableWidth: availableWidth, widthMeasureMode: widthMeasureMode,
+            availableHeight: availableHeight, heightMeasureMode: heightMeasureMode
+          },
+          {
+            availableWidth: availableWidth, widthMeasureMode: widthMeasureMode, computedWidth: 1,
+            availableHeight: availableHeight, heightMeasureMode: heightMeasureMode, computedHeight: 2
+          }
+        );
+      });
+    });
+  });
+  
+  it('should reuse cache entry with unconstrained width when width mode is "exactly" and available width == measurement', function() {
+    measureModes.forEach(function(heightMeasureMode) {
+      var computedWidth = 100;
+      var computedHeight = 200;
+      var availableHeight = heightMeasureMode === 'undefined' ? undefined : computedHeight;
+      
+      assertCanReuse(
+        {
+          availableWidth: computedWidth, widthMeasureMode: 'exactly',
+          availableHeight: availableHeight, heightMeasureMode: heightMeasureMode
+        },
+        {
+          availableWidth: undefined, widthMeasureMode: 'undefined', computedWidth: computedWidth,
+          availableHeight: availableHeight, heightMeasureMode: heightMeasureMode, computedHeight: computedHeight
+        }
+      );
+    });
+  });
+    
+  it('should reuse cache entry with unconstrained height when height mode is "exactly" and height == measurement', function() {
+    measureModes.forEach(function(widthMeasureMode) {
+      var computedWidth = 100;
+      var computedHeight = 200;
+      var availableWidth = widthMeasureMode === 'undefined' ? undefined : computedWidth;
+        
+      assertCanReuse(
+        {
+          availableWidth: availableWidth, widthMeasureMode: widthMeasureMode,
+          availableHeight: computedHeight, heightMeasureMode: 'exactly'
+        },
+        {
+          availableWidth: availableWidth, widthMeasureMode: widthMeasureMode, computedWidth: computedWidth,
+          availableHeight: undefined, heightMeasureMode: 'undefined', computedHeight: computedHeight
+        }
+      );
+    });
   });
 });
 
@@ -1238,7 +1385,7 @@ describe('Layout', function() {
     testLayoutAgainstExpectedOnly(
       {style: {width: 320, flexDirection: 'column'}, children: [
         {style: {measure: measureWithRatio2}},
-        {style: {height: 100, flexDirection: 'row'}, children: [
+        {style: {height: 100, flexDirection: 'row', overflow: 'hidden'}, children: [
           {style: {measure: measureWithRatio2}},
           {style: {measure: measureWithRatio2}}
         ]},
@@ -1354,14 +1501,16 @@ describe('Layout', function() {
   });
 
   it('should layout node with text bounded by grand-parent', function() {
-    testLayout(
+    testLayoutAgainstExpectedOnly(
       {style: {width: 100, padding: 10, alignSelf: 'flex-start'}, children: [
         {style: {margin: 10, alignSelf: 'flex-start'}, children: [
           {style: {measure: text(texts.big)}}
         ]}
       ]},
       {width: 100, height: 40 + textSizes.bigHeight, top: 0, left: 0, children: [
-        {width: textSizes.bigMinWidth, height: textSizes.bigHeight, top: 20, left: 20, children: [
+        // In the flexbox engine implementation, min width of text is not supported so we max
+        // out at the amount of available space (60)
+        {width: Math.min(60, textSizes.bigMinWidth), height: textSizes.bigHeight, top: 20, left: 20, children: [
           {width: textSizes.bigMinWidth, height: textSizes.bigHeight, top: 0, left: 0}
         ]}
       ]}
@@ -2149,6 +2298,30 @@ describe('Layout', function() {
       ]}
     );
   });
+  
+  it('should center flexible item with max size', function() {
+    testLayout(
+      {style: {width: 1000, height: 1000, flexDirection: 'row', justifyContent: 'center'}, children: [
+        {style: {flex: 1, maxWidth: 600, height: 1000}}
+      ]},
+      {width: 1000, height: 1000, top: 0, left: 0, children: [
+        {width: 600, height: 1000, top: 0, left: 200}
+      ]}
+    );
+  });
+  
+  it('should correctly size flexible items with flex basis and a max width', function() {
+    testLayout(
+      {style: {width: 1000, height: 1000, flexDirection: 'row'}, children: [
+        {style: {flex: 1, width: 100, height: 1000}},
+        {style: {flex: 1, width: 100, maxWidth: 200, height: 1000}}
+      ]},
+      {width: 1000, height: 1000, top: 0, left: 0, children: [
+        {width: 800, height: 1000, top: 0, left: 0},
+        {width: 200, height: 1000, top: 0, left: 800}
+      ]}
+    );
+  });
 
   xit('should layout node with a nested sibling child with width', function() {
     testLayout(
@@ -2485,6 +2658,307 @@ describe('Layout', function() {
   });
 });
 
+describe('Layout flex:-1', function() {
+  // Tests for items with flex:-1 in a container with flexDirection:column
+  
+  it('should not shrink column node when there is space left over', function() {
+    testLayout(
+      {style: {width: 100, height: 100}, children: [
+        {style: {width: 100, flex: -1}, children: [
+          {style: {width: 100, height: 25}}
+        ]}
+      ]},
+      {width: 100, height: 100, top: 0, left: 0, children: [
+        {width: 100, height: 25, top: 0, left: 0, children: [
+          {width: 100, height: 25, top: 0, left: 0}
+        ]}
+      ]}
+    );
+  });
+  
+  it('should shrink column node when there is not any space left over', function() {
+    testLayout(
+      {style: {width: 100, height: 100}, children: [
+        {style: {width: 100, flex: -1}, children: [
+          {style: {width: 100, height: 200}}
+        ]}
+      ]},
+      {width: 100, height: 100, top: 0, left: 0, children: [
+        {width: 100, height: 100, top: 0, left: 0, children: [
+          {width: 100, height: 200, top: 0, left: 0}
+        ]}
+      ]}
+    );
+  });
+  
+  it('should not shrink column node with siblings when there is space left over', function() {
+    testLayout(
+      {style: {width: 100, height: 100}, children: [
+        {style: {width: 100, height: 25}},
+        {style: {width: 100, flex: -1}, children: [
+          {style: {width: 100, height: 30}}
+        ]},
+        {style: {width: 100, height: 15}},
+      ]},
+      {width: 100, height: 100, top: 0, left: 0, children: [
+        {width: 100, height: 25, top: 0, left: 0},
+        {width: 100, height: 30, top: 25, left: 0, children: [
+          {width: 100, height: 30, top: 0, left: 0}
+        ]},
+        {width: 100, height: 15, top: 55, left: 0},
+      ]}
+    );
+  });
+  
+  it('should shrink column node with siblings when there is not any space left over', function() {
+    testLayout(
+      {style: {width: 100, height: 100}, children: [
+        {style: {width: 100, height: 25}},
+        {style: {width: 100, flex: -1}, children: [
+          {style: {width: 100, height: 80}}
+        ]},
+        {style: {width: 100, height: 15}},
+      ]},
+      {width: 100, height: 100, top: 0, left: 0, children: [
+        {width: 100, height: 25, top: 0, left: 0},
+        {width: 100, height: 60, top: 25, left: 0, children: [
+          {width: 100, height: 80, top: 0, left: 0}
+        ]},
+        {width: 100, height: 15, top: 85, left: 0},
+      ]}
+    );
+  });
+  
+  it('should shrink column nodes proportional to their main size when there is not any space left over', function() {
+    testLayout(
+      {style: {width: 100, height: 100}, children: [
+        {style: {width: 100, height: 30, flex: -1}},
+        {style: {width: 100, height: 40}},
+        {style: {width: 100, height: 50, flex: -1}}
+      ]},
+      {width: 100, height: 100, top: 0, left: 0, children: [
+        {width: 100, height: 22.5, top: 0, left: 0},
+        {width: 100, height: 40, top: 22.5, left: 0},
+        {width: 100, height: 37.5, top: 62.5, left: 0}
+      ]}
+    );
+  });
+  
+  // Tests for items with flex:-1 and overflow:visible in a container with flexDirection:row
+  
+  it('should not shrink visible row node when there is space left over', function() {
+    testLayout(
+      {style: {width: 100, height: 100, flexDirection: 'row'}, children: [
+        {style: {height: 100, flex: -1}, children: [
+          {style: {width: 25, height: 100}}
+        ]}
+      ]},
+      {width: 100, height: 100, top: 0, left: 0, children: [
+        {width: 25, height: 100, top: 0, left: 0, children: [
+          {width: 25, height: 100, top: 0, left: 0}
+        ]}
+      ]}
+    );
+  });
+  
+  it('should shrink visible row node when there is not any space left over', function() {
+    testLayout(
+      {style: {width: 100, height: 100, flexDirection: 'row'}, children: [
+        {style: {height: 100, flex: -1}, children: [
+          {style: {width: 200, height: 100}}
+        ]}
+      ]},
+      {width: 100, height: 100, top: 0, left: 0, children: [
+        // width would be 100 if we implemented https://www.w3.org/TR/css-flexbox-1/#min-size-auto and min-width didn't default to 0
+        {width: 100, height: 100, top: 0, left: 0, children: [
+          {width: 200, height: 100, top: 0, left: 0}
+        ]}
+      ]}
+    );
+  });
+  
+  it('should not shrink visible row node with siblings when there is space left over', function() {
+    testLayout(
+      {style: {width: 100, height: 100, flexDirection: 'row'}, children: [
+        {style: {width: 25, height: 100}},
+        {style: {height: 100, flex: -1}, children: [
+          {style: {width: 30, height: 100}}
+        ]},
+        {style: {width: 15, height: 100}},
+      ]},
+      {width: 100, height: 100, top: 0, left: 0, children: [
+        {width: 25, height: 100, top: 0, left: 0},
+        {width: 30, height: 100, top: 0, left: 25, children: [
+          {width: 30, height: 100, top: 0, left: 0}
+        ]},
+        {width: 15, height: 100, top: 0, left: 55},
+      ]}
+    );
+  });
+  
+  it('should shrink visible row node with siblings when there is not any space left over', function() {
+    testLayout(
+      {style: {width: 100, height: 100, flexDirection: 'row'}, children: [
+        {style: {width: 25, height: 100}},
+        {style: {height: 100, flex: -1}, children: [
+          {style: {width: 80, height: 100}}
+        ]},
+        {style: {width: 15, height: 100}},
+      ]},
+      {width: 100, height: 100, top: 0, left: 0, children: [
+        {width: 25, height: 100, top: 0, left: 0},
+        // width would be 80 if we implemented https://www.w3.org/TR/css-flexbox-1/#min-size-auto and min-width didn't default to 0
+        {width: 60, height: 100, top: 0, left: 25, children: [
+          {width: 80, height: 100, top: 0, left: 0}
+        ]},
+        {width: 15, height: 100, top: 0, left: 85},
+      ]}
+    );
+  });
+  
+  it('should shrink visible row nodes when there is not any space left over', function() {
+    testLayout(
+      {style: {width: 100, height: 100, flexDirection: 'row'}, children: [
+        {style: {width: 30, height: 100, flex: -1}},
+        {style: {width: 40, height: 100}},
+        {style: {width: 50, height: 100, flex: -1}}
+      ]},
+      {width: 100, height: 100, top: 0, left: 0, children: [
+        // width would be 30 if we implemented https://www.w3.org/TR/css-flexbox-1/#min-size-auto and min-width didn't default to 0
+        {width: 22.5, height: 100, top: 0, left: 0},
+        {width: 40, height: 100, top: 0, left: 22.5},
+        // width would be 50 if we implemented https://www.w3.org/TR/css-flexbox-1/#min-size-auto and min-width didn't default to 0
+        {width: 37.5, height: 100, top: 0, left: 62.5}
+      ]}
+    );
+  });
+  
+  // Tests for items with flex:-1 and overflow:hidden in a container with flexDirection:row
+  
+  it('should not shrink hidden row node when there is space left over', function() {
+    testLayout(
+      {style: {width: 100, height: 100, flexDirection: 'row'}, children: [
+        {style: {height: 100, flex: -1, overflow: 'hidden'}, children: [
+          {style: {width: 25, height: 100}}
+        ]}
+      ]},
+      {width: 100, height: 100, top: 0, left: 0, children: [
+        {width: 25, height: 100, top: 0, left: 0, children: [
+          {width: 25, height: 100, top: 0, left: 0}
+        ]}
+      ]}
+    );
+  });
+
+  it('should shrink hidden row node when there is not any space left over', function() {
+    testLayout(
+      {style: {width: 100, height: 100, flexDirection: 'row'}, children: [
+        {style: {height: 100, flex: -1, overflow: 'hidden'}, children: [
+          {style: {width: 200, height: 100}}
+        ]}
+      ]},
+      {width: 100, height: 100, top: 0, left: 0, children: [
+        {width: 100, height: 100, top: 0, left: 0, children: [
+          {width: 200, height: 100, top: 0, left: 0}
+        ]}
+      ]}
+    );
+  });
+  
+  it('should not shrink hidden row node with siblings when there is space left over', function() {
+    testLayout(
+      {style: {width: 100, height: 100, flexDirection: 'row'}, children: [
+        {style: {width: 25, height: 100}},
+        {style: {height: 100, flex: -1, overflow: 'hidden'}, children: [
+          {style: {width: 30, height: 100}}
+        ]},
+        {style: {width: 15, height: 100}},
+      ]},
+      {width: 100, height: 100, top: 0, left: 0, children: [
+        {width: 25, height: 100, top: 0, left: 0},
+        {width: 30, height: 100, top: 0, left: 25, children: [
+          {width: 30, height: 100, top: 0, left: 0}
+        ]},
+        {width: 15, height: 100, top: 0, left: 55},
+      ]}
+    );
+  });
+  
+  it('should shrink hidden row node with siblings when there is not any space left over', function() {
+    testLayout(
+      {style: {width: 100, height: 100, flexDirection: 'row'}, children: [
+        {style: {width: 25, height: 100}},
+        {style: {height: 100, flex: -1, overflow: 'hidden'}, children: [
+          {style: {width: 80, height: 100}}
+        ]},
+        {style: {width: 15, height: 100}},
+      ]},
+      {width: 100, height: 100, top: 0, left: 0, children: [
+        {width: 25, height: 100, top: 0, left: 0},
+        {width: 60, height: 100, top: 0, left: 25, children: [
+          {width: 80, height: 100, top: 0, left: 0}
+        ]},
+        {width: 15, height: 100, top: 0, left: 85},
+      ]}
+    );
+  });
+  
+  it('should shrink hidden row nodes proportional to their main size when there is not any space left over', function() {
+    testLayout(
+      {style: {width: 100, height: 100, flexDirection: 'row'}, children: [
+        {style: {width: 30, height: 100, flex: -1, overflow: 'hidden'}},
+        {style: {width: 40, height: 100}},
+        {style: {width: 50, height: 100, flex: -1, overflow: 'hidden'}}
+      ]},
+      {width: 100, height: 100, top: 0, left: 0, children: [
+        {width: 22.5, height: 100, top: 0, left: 0},
+        {width: 40, height: 100, top: 0, left: 22.5},
+        {width: 37.5, height: 100, top: 0, left: 62.5}
+      ]}
+    );
+  });
+  
+  // Tests for items with flex:-1 containing a text node
+  
+  it('should not shrink text node with siblings when there is space left over', function() {
+    testLayoutAgainstExpectedOnly(
+      {style: {width: 213, height: 100, flexDirection: 'row'}, children: [
+        {style: {width: 25, height: 100}},
+        {style: {height: 100, flex: -1, flexDirection: 'row', alignItems: 'flex-start'}, children: [
+          {style: {measure: text(texts.big)}}
+        ]},
+        {style: {width: 15, height: 100}},
+      ]},
+      {width: 213, height: 100, top: 0, left: 0, children: [
+        {width: 25, height: 100, top: 0, left: 0},
+        {width: textSizes.bigWidth, height: 100, top: 0, left: 25, children: [
+          {width: textSizes.bigWidth, height: textSizes.smallHeight, top: 0, left: 0}
+        ]},
+        {width: 15, height: 100, top: 0, left: 25 + textSizes.bigWidth},
+      ]}
+    );
+  });
+  
+  it('should shrink text node with siblings when there is not any space left over', function() {
+    testLayout(
+      {style: {width: 140, height: 100, flexDirection: 'row'}, children: [
+        {style: {width: 25, height: 100}},
+        {style: {height: 100, flex: -1, flexDirection: 'row', alignItems: 'flex-start'}, children: [
+          {style: {flex: -1, measure: text(texts.big)}}
+        ]},
+        {style: {width: 15, height: 100}},
+      ]},
+      {width: 140, height: 100, top: 0, left: 0, children: [
+        {width: 25, height: 100, top: 0, left: 0},
+        {width: textSizes.bigMinWidth, height: 100, top: 0, left: 25, children: [
+          {width: textSizes.bigMinWidth, height: textSizes.bigHeight, top: 0, left: 0}
+        ]},
+        {width: 15, height: 100, top: 0, left: 25 + textSizes.bigMinWidth},
+      ]}
+    );
+  });
+});
+
 describe('Layout alignContent', function() {
 
   it('should layout with alignContent: stretch, and alignItems: flex-start', function() {

src/csharp/Facebook.CSSLayout/Assertions.cs

@@ -18,5 +18,10 @@ namespace Facebook.CSSLayout
             Debug.Assert(v != null);
             return v;
         }
+        
+        public static void assertCondition(bool condition, string explanation)
+        {
+            Debug.Assert(condition, explanation);
+        }
     }
 }

src/csharp/Facebook.CSSLayout/CSSCachedMeasurement.cs

@@ -0,0 +1,22 @@
+/**
+ * Copyright (c) 2014, Facebook, Inc.
+ * All rights reserved.
+ *
+ * This source code is licensed under the BSD-style license found in the
+ * LICENSE file in the root directory of this source tree. An additional grant
+ * of patent rights can be found in the PATENTS file in the same directory.
+ */
+
+namespace Facebook.CSSLayout
+{
+    sealed class CSSCachedMeasurement
+    {
+        public float availableWidth;
+        public float availableHeight;
+        public CSSMeasureMode? widthMeasureMode = null;
+        public CSSMeasureMode? heightMeasureMode = null;
+
+        public float computedWidth;
+        public float computedHeight;
+    }
+}

src/csharp/Facebook.CSSLayout/CSSLayout.cs

@@ -16,6 +16,10 @@ namespace Facebook.CSSLayout
 
     class CSSLayout
     {
+        // This value was chosen based on empiracle data. Even the most complicated
+        // layouts should not require more than 16 entries to fit within the cache.
+        public const int MAX_CACHED_RESULT_COUNT = 16;
+
         public const int POSITION_LEFT = 0;
         public const int POSITION_TOP = 1;
         public const int POSITION_RIGHT = 2;
@@ -25,12 +29,25 @@ namespace Facebook.CSSLayout
         public const int DIMENSION_HEIGHT = 1;
 
         public float[] position = new float[4];
-        public float[] dimensions = new float[2];
+        public float[] dimensions = {
+            CSSConstants.Undefined,
+            CSSConstants.Undefined
+        };
         public CSSDirection direction = CSSDirection.LTR;
 
-        /**
-        * This should always get called before calling {@link LayoutEngine#layoutNode(CSSNode, float)}
-        */
+        public float flexBasis;
+
+        public int generationCount;
+        public CSSDirection? lastParentDirection;
+
+        public int nextCachedMeasurementsIndex;
+        public CSSCachedMeasurement[] cachedMeasurements = new CSSCachedMeasurement[MAX_CACHED_RESULT_COUNT];
+        public float[] measuredDimensions = {
+            CSSConstants.Undefined,
+            CSSConstants.Undefined
+        };
+
+        public CSSCachedMeasurement cachedLayout = new CSSCachedMeasurement();
 
         public void resetResult()
         {
@@ -38,17 +55,18 @@ namespace Facebook.CSSLayout
             FillArray(dimensions, CSSConstants.Undefined);
 
             direction = CSSDirection.LTR;
-        }
 
-        public void copy(CSSLayout layout)
-        {
-            position[POSITION_LEFT] = layout.position[POSITION_LEFT];
-            position[POSITION_TOP] = layout.position[POSITION_TOP];
-            position[POSITION_RIGHT] = layout.position[POSITION_RIGHT];
-            position[POSITION_BOTTOM] = layout.position[POSITION_BOTTOM];
-            dimensions[DIMENSION_WIDTH] = layout.dimensions[DIMENSION_WIDTH];
-            dimensions[DIMENSION_HEIGHT] = layout.dimensions[DIMENSION_HEIGHT];
-            direction = layout.direction;
+            flexBasis = 0;
+
+            generationCount = 0;
+            lastParentDirection = null;
+
+            nextCachedMeasurementsIndex = 0;
+            measuredDimensions[DIMENSION_WIDTH] = CSSConstants.Undefined;
+            measuredDimensions[DIMENSION_HEIGHT] = CSSConstants.Undefined;
+
+            cachedLayout.widthMeasureMode = null;
+            cachedLayout.heightMeasureMode = null;
         }
 
         public override string ToString()

src/csharp/Facebook.CSSLayout/CSSLayoutContext.cs

@@ -22,5 +22,6 @@ namespace Facebook.CSSLayout
     {
         /*package*/
         public MeasureOutput measureOutput = new MeasureOutput();
+        public int currentGenerationCount;
     }
 }

src/csharp/Facebook.CSSLayout/CSSMeasureMode.cs

@@ -1,4 +1,4 @@
-/**
+/**
  * Copyright (c) 2014, Facebook, Inc.
  * All rights reserved.
  *

src/csharp/Facebook.CSSLayout/CSSNode.cs

@@ -58,8 +58,7 @@ namespace Facebook.CSSLayout
         internal readonly CachedCSSLayout lastLayout = new CachedCSSLayout();
 
         internal int lineIndex = 0;
-        internal /*package*/ CSSNode nextAbsoluteChild;
-        internal /*package*/ CSSNode nextFlexChild;
+        internal /*package*/ CSSNode nextChild;
 
         // 4 is kinda arbitrary, but the default of 10 seems really high for an average View.
         readonly List<CSSNode> mChildren = new List<CSSNode>(4);
@@ -155,7 +154,6 @@ namespace Facebook.CSSLayout
 
         public void CalculateLayout()
         {
-            layout.resetResult();
             LayoutEngine.layoutNode(DummyLayoutContext, this, CSSConstants.Undefined, CSSConstants.Undefined, null);
         }
 

src/csharp/Facebook.CSSLayout/CSSOverflow.cs

@@ -0,0 +1,17 @@
+/**
+ * Copyright (c) 2014, Facebook, Inc.
+ * All rights reserved.
+ *
+ * This source code is licensed under the BSD-style license found in the
+ * LICENSE file in the root directory of this source tree. An additional grant
+ * of patent rights can be found in the PATENTS file in the same directory.
+ */
+
+namespace Facebook.CSSLayout
+{
+    public enum CSSOverflow
+    {
+        Visible,
+        Hidden
+    }
+}

src/csharp/Facebook.CSSLayout/CSSStyle.cs

@@ -22,6 +22,7 @@ namespace Facebook.CSSLayout
         public CSSAlign alignSelf = CSSAlign.Auto;
         public CSSPositionType positionType = CSSPositionType.Relative;
         public CSSWrap flexWrap = CSSWrap.NoWrap;
+        public CSSOverflow overflow = CSSOverflow.Visible;
         public float flex;
 
         public Spacing margin = new Spacing();

src/csharp/Facebook.CSSLayout/Facebook.CSSLayout.csproj

@@ -41,14 +41,16 @@
     <Compile Include="Assertions.cs" />
     <Compile Include="CachedCSSLayout.cs" />
     <Compile Include="CSSAlign.cs" />
+    <Compile Include="CSSCachedMeasurement.cs" />
     <Compile Include="CSSConstants.cs" />
     <Compile Include="CSSDirection.cs" />
     <Compile Include="CSSFlexDirection.cs" />
     <Compile Include="CSSJustify.cs" />
-    <Compile Include="CSSMeasureMode.cs" />
     <Compile Include="CSSLayout.cs" />
     <Compile Include="CSSLayoutContext.cs" />
+    <Compile Include="CSSMeasureMode.cs" />
     <Compile Include="CSSNode.cs" />
+    <Compile Include="CSSOverflow.cs" />
     <Compile Include="CSSPositionType.cs" />
     <Compile Include="CSSStyle.cs" />
     <Compile Include="CSSWrap.cs" />
@@ -68,4 +70,4 @@
   <Target Name="AfterBuild">
   </Target>
   -->
-</Project>
+</Project>

src/java/src/com/facebook/csslayout/CSSCachedMeasurement.java

@@ -0,0 +1,19 @@
+/**
+ * Copyright (c) 2014, Facebook, Inc.
+ * All rights reserved.
+ *
+ * This source code is licensed under the BSD-style license found in the
+ * LICENSE file in the root directory of this source tree. An additional grant
+ * of patent rights can be found in the PATENTS file in the same directory.
+ */
+package com.facebook.csslayout;
+
+public class CSSCachedMeasurement {
+  public float availableWidth;
+  public float availableHeight;
+  public CSSMeasureMode widthMeasureMode = null;
+  public CSSMeasureMode heightMeasureMode = null;
+  
+  public float computedWidth;
+  public float computedHeight;
+}

src/java/src/com/facebook/csslayout/CSSLayout.java

@@ -14,6 +14,10 @@ import java.util.Arrays;
  * Where the output of {@link LayoutEngine#layoutNode(CSSNode, float)} will go in the CSSNode.
  */
 public class CSSLayout {
+  // This value was chosen based on empiracle data. Even the most complicated
+  // layouts should not require more than 16 entries to fit within the cache.
+  public static final int MAX_CACHED_RESULT_COUNT = 16;
+  
   public static final int POSITION_LEFT = 0;
   public static final int POSITION_TOP = 1;
   public static final int POSITION_RIGHT = 2;
@@ -25,24 +29,38 @@ public class CSSLayout {
   public float[] position = new float[4];
   public float[] dimensions = new float[2];
   public CSSDirection direction = CSSDirection.LTR;
-
-  /**
-   * This should always get called before calling {@link LayoutEngine#layoutNode(CSSNode, float)}
-   */
+  
+  public float flexBasis;
+  
+  public int generationCount;
+  public CSSDirection lastParentDirection;
+  
+  public int nextCachedMeasurementsIndex;
+  public CSSCachedMeasurement[] cachedMeasurements = new CSSCachedMeasurement[MAX_CACHED_RESULT_COUNT];
+  public float[] measuredDimensions = new float[2];
+  
+  public CSSCachedMeasurement cachedLayout = new CSSCachedMeasurement();
+  
+  CSSLayout() {
+    resetResult();
+  }
+  
   public void resetResult() {
     Arrays.fill(position, 0);
     Arrays.fill(dimensions, CSSConstants.UNDEFINED);
     direction = CSSDirection.LTR;
-  }
-
-  public void copy(CSSLayout layout) {
-    position[POSITION_LEFT] = layout.position[POSITION_LEFT];
-    position[POSITION_TOP] = layout.position[POSITION_TOP];
-    position[POSITION_RIGHT] = layout.position[POSITION_RIGHT];
-    position[POSITION_BOTTOM] = layout.position[POSITION_BOTTOM];
-    dimensions[DIMENSION_WIDTH] = layout.dimensions[DIMENSION_WIDTH];
-    dimensions[DIMENSION_HEIGHT] = layout.dimensions[DIMENSION_HEIGHT];
-    direction = layout.direction;
+    
+    flexBasis = 0;
+    
+    generationCount = 0;
+    lastParentDirection = null;
+    
+    nextCachedMeasurementsIndex = 0;
+    measuredDimensions[DIMENSION_WIDTH] = CSSConstants.UNDEFINED;
+    measuredDimensions[DIMENSION_HEIGHT] = CSSConstants.UNDEFINED;
+    
+    cachedLayout.widthMeasureMode = null;
+    cachedLayout.heightMeasureMode = null;
   }
 
   @Override

src/java/src/com/facebook/csslayout/CSSLayoutContext.java

@@ -17,4 +17,5 @@ package com.facebook.csslayout;
  */
 public class CSSLayoutContext {
   /*package*/ final MeasureOutput measureOutput = new MeasureOutput();
+  int currentGenerationCount;
 }

src/java/src/com/facebook/csslayout/CSSNode.java

@@ -63,9 +63,8 @@ public class CSSNode {
 
   public int lineIndex = 0;
 
-  /*package*/ CSSNode nextAbsoluteChild;
-  /*package*/ CSSNode nextFlexChild;
-
+  /*package*/ CSSNode nextChild;
+  
   private @Nullable ArrayList<CSSNode> mChildren;
   private @Nullable CSSNode mParent;
   private @Nullable MeasureFunction mMeasureFunction = null;
@@ -139,7 +138,6 @@ public class CSSNode {
    * Performs the actual layout and saves the results in {@link #layout}
    */
   public void calculateLayout(CSSLayoutContext layoutContext) {
-    layout.resetResult();
     LayoutEngine.layoutNode(layoutContext, this, CSSConstants.UNDEFINED, CSSConstants.UNDEFINED, null);
   }
 

src/java/src/com/facebook/csslayout/CSSOverflow.java

@@ -0,0 +1,14 @@
+/**
+ * Copyright (c) 2014, Facebook, Inc.
+ * All rights reserved.
+ *
+ * This source code is licensed under the BSD-style license found in the
+ * LICENSE file in the root directory of this source tree. An additional grant
+ * of patent rights can be found in the PATENTS file in the same directory.
+ */
+package com.facebook.csslayout;
+
+public enum CSSOverflow {
+  VISIBLE,
+  HIDDEN,
+}

src/java/src/com/facebook/csslayout/CSSStyle.java

@@ -23,6 +23,7 @@ public class CSSStyle {
   public CSSAlign alignSelf;
   public CSSPositionType positionType;
   public CSSWrap flexWrap;
+  public CSSOverflow overflow;
   public float flex;
 
   public Spacing margin = new Spacing();
@@ -51,6 +52,7 @@ public class CSSStyle {
     alignSelf = CSSAlign.AUTO;
     positionType = CSSPositionType.RELATIVE;
     flexWrap = CSSWrap.NOWRAP;
+    overflow = CSSOverflow.VISIBLE;
     flex = 0f;
 
     margin.reset();;

src/java/tests/com/facebook/csslayout/LayoutCachingTest.java

@@ -43,7 +43,7 @@ public class LayoutCachingTest {
     root.addChildAt(c0, 0);
     root.addChildAt(c1, 1);
     c0.addChildAt(c0c0, 0);
-
+    
     root.calculateLayout(layoutContext);
     assertTreeHasNewLayout(true, root);
     markLayoutAppliedForTree(root);

src/transpile.js

@@ -39,8 +39,7 @@ global.layoutTestUtils = {
 };
 
 global.describe = function(name, cb) {
-  if (name === 'Layout' ||
-      name === 'Layout alignContent') {
+  if (name.toLowerCase().indexOf('javascript only') === -1) {
     cb();
   }
 };
@@ -175,6 +174,10 @@ function printLayout(test) {
       'exactly': 'CSS_MEASURE_MODE_EXACTLY',
       'at-most': 'CSS_MEASURE_MODE_AT_MOST'
     });
+    addEnum(node, 'overflow', 'overflow', {
+      'visible': 'CSS_OVERFLOW_VISIBLE',
+      'hidden': 'CSS_OVERFLOW_HIDDEN'
+    });
     addFloat(node, 'flex', 'flex');
     addFloat(node, 'width', 'dimensions[CSS_WIDTH]');
     addFloat(node, 'height', 'dimensions[CSS_HEIGHT]');
@@ -256,8 +259,13 @@ function printLayout(test) {
 
 function transpileAnnotatedJStoC(jsCode) {
   return jsCode
+    .replace(/'abs-layout'/g, '"abs-layout"')
+    .replace(/'abs-measure'/g, '"abs-measure"')
+    .replace(/'flex'/g, '"flex"')
+    .replace(/'measure'/g, '"measure"')
+    .replace(/'stretch'/g, '"stretch"')
     .replace('node.style.measure', 'node.measure')
-    .replace(/null/g, 'NULL')
+    .replace(/undefined/g, 'NULL')
     .replace(/\.children\.length/g, '.children_count')
     .replace(/\.width/g, '.dimensions[CSS_WIDTH]')
     .replace(/\.height/g, '.dimensions[CSS_HEIGHT]')
@@ -266,23 +274,30 @@ function transpileAnnotatedJStoC(jsCode) {
     .replace(/\.minWidth/g, '.minDimensions[CSS_WIDTH]')
     .replace(/\.minHeight/g, '.minDimensions[CSS_HEIGHT]')
     .replace(/\.lineIndex/g, '.line_index')
-    .replace(/\.nextAbsoluteChild/g, '.next_absolute_child')
-    .replace(/\.nextFlexChild/g, '.next_flex_child')
-    .replace(/layout\[dim/g, 'layout.dimensions[dim')
+    .replace(/\.nextChild/g, '.next_child')
+    .replace(/\.flexBasis/g, '.flex_basis')
     .replace(/layout\[pos/g, 'layout.position[pos')
     .replace(/layout\[leading/g, 'layout.position[leading')
     .replace(/layout\[trailing/g, 'layout.position[trailing')
+    .replace(/layout\[measuredDim/g, 'layout.measured_dimensions[dim')
+    .replace(/layout\.measuredWidth/g, 'layout.measured_dimensions[CSS_WIDTH]')
+    .replace(/layout\.measuredHeight/g, 'layout.measured_dimensions[CSS_HEIGHT]')
     .replace(/style\[dim/g, 'style.dimensions[dim')
+    .replace(/style\[CSS_LEFT/g, 'style.position[CSS_LEFT')
+    .replace(/style\[CSS_TOP/g, 'style.position[CSS_TOP')
+    .replace(/style\[CSS_RIGHT/g, 'style.position[CSS_RIGHT')
+    .replace(/style\[CSS_BOTTOM/g, 'style.position[CSS_BOTTOM')
     .replace(/node.children\[i\]/g, 'node->get_child(node->context, i)')
-    .replace(/node.children\[ii\]/g, 'node->get_child(node->context, ii)')
+    .replace(/node.children\[j\]/g, 'node->get_child(node->context, j)')
     .replace(/node\./g, 'node->')
     .replace(/child\./g, 'child->')
-    .replace(/parent\./g, 'parent->')
     .replace(/currentAbsoluteChild\./g, 'currentAbsoluteChild->')
-    .replace(/currentFlexChild\./g, 'currentFlexChild->')
+    .replace(/currentRelativeChild\./g, 'currentRelativeChild->')
     .replace(/getPositionType\((.+?)\)/g, '$1->style.position_type')
     .replace(/getJustifyContent\((.+?)\)/g, '$1->style.justify_content')
     .replace(/getAlignContent\((.+?)\)/g, '$1->style.align_content')
+    .replace(/assert\((.+?),\s*'(.+?)'\);/g, 'assert($1); // $2')
+    .replace(/getOverflow\((.+?)\)/g, '$1->style.overflow')
     .replace(/var\/\*\(c\)!([^*]+)\*\//g, '$1')
     .replace(/var\/\*([^\/]+)\*\//g, '$1')
     .replace(/ === /g, ' == ')
@@ -290,8 +305,7 @@ function transpileAnnotatedJStoC(jsCode) {
     .replace(/\n {2}/g, '\n')
     .replace(/\/\*\(c\)!([^*]+)\*\//g, '$1')
     .replace(/\/[*]!([^*]+)[*]\//g, '$1')
-    .replace(/\/\*\(java\)!([^*]+)\*\//g, '')
-    .split('\n').slice(1, -1).join('\n');
+    .replace(/\/\*\(java\)!([^*]+)\*\//g, '');
 }
 
 function makeConstDefs() {
@@ -318,14 +332,18 @@ function generateFile(fileName, generatedContent) {
   fs.writeFileSync(fileName, content);
 }
 
+// Extract the function body by trimming the first ('function layoutNode(...) {') and
+// last ('}') lines. Also, start the function body with a blank line so that regexes
+// that use \n to match the start of a line will match the actual first line.
+var computeLayoutCode = [''].concat(computeLayout.toString().split('\n').slice(1, -1)).join('\n');
 
 var allTestsInC = allTests.map(printLayout);
 generateFile(__dirname + '/__tests__/Layout-test.c', allTestsInC.join('\n\n'));
 generateFile(__dirname + '/Layout-test-utils.c', makeConstDefs());
-generateFile(__dirname + '/Layout.c', transpileAnnotatedJStoC(computeLayout.toString()));
-generateFile(__dirname + '/java/src/com/facebook/csslayout/LayoutEngine.java', JavaTranspiler.transpileLayoutEngine(computeLayout.toString()));
+generateFile(__dirname + '/Layout.c', transpileAnnotatedJStoC(computeLayoutCode));
+generateFile(__dirname + '/java/src/com/facebook/csslayout/LayoutEngine.java', JavaTranspiler.transpileLayoutEngine(computeLayoutCode));
 generateFile(__dirname + '/java/tests/com/facebook/csslayout/TestConstants.java', JavaTranspiler.transpileCConstDefs(makeConstDefs()));
 generateFile(__dirname + '/java/tests/com/facebook/csslayout/LayoutEngineTest.java', JavaTranspiler.transpileCTestsArray(allTestsInC));
-generateFile(__dirname + '/csharp/Facebook.CSSLayout/LayoutEngine.cs', CSharpTranspiler.transpileLayoutEngine(computeLayout.toString()));
+generateFile(__dirname + '/csharp/Facebook.CSSLayout/LayoutEngine.cs', CSharpTranspiler.transpileLayoutEngine(computeLayoutCode));
 generateFile(__dirname + '/csharp/Facebook.CSSLayout.Tests/TestConstants.cs', CSharpTranspiler.transpileCConstDefs(makeConstDefs()));
 generateFile(__dirname + '/csharp/Facebook.CSSLayout.Tests/LayoutEngineTest.cs', CSharpTranspiler.transpileCTestsArray(allTestsInC));