Improve JS bindings

Summary:
- Fix a few things related to how npm should publish the package (sources were in the gitignore file, so I think it would have break the build during install - I fixed this by adding a npmignore that should override the gitignore rules)

- The enumerations values are now generated directly from `enums.py`

- I added percent unit support (#258) to the bindings (`.setWidthPercent` is currently exposed, but I've also added a very very little parsing to also support `.setWidth("100%")` and `.setWidth(.getWidth())`), added the missing tests, and fixed Travis.
Closes https://github.com/facebook/yoga/pull/314

Reviewed By: mikearmstrong001

Differential Revision: D4377198

Pulled By: emilsjolander

fbshipit-source-id: 774dfafd416f5421f3be59a1d181eb7056487abe

javascript/sources/entry-common.js

@@ -19,57 +19,11 @@ function patch(prototype, name, fn) {
 
 module.exports = function (bind, lib) {
 
-    let constants = {};
+    let constants = Object.assign({
 
-    constants.ALIGN_AUTO = 0;
-    constants.ALIGN_CENTER = 2;
-    constants.ALIGN_FLEX_END = 3;
-    constants.ALIGN_FLEX_START = 1;
-    constants.ALIGN_STRETCH = 4;
+        UNDEFINED: NaN
 
-    constants.DIRECTION_INHERIT = 0;
-    constants.DIRECTION_LTR = 1;
-    constants.DIRECTION_RTL = 2;
-
-    constants.EDGE_ALL = 8;
-    constants.EDGE_BOTTOM = 3;
-    constants.EDGE_END = 5;
-    constants.EDGE_HORIZONTAL = 6;
-    constants.EDGE_LEFT = 0;
-    constants.EDGE_RIGHT = 2;
-    constants.EDGE_START = 4;
-    constants.EDGE_TOP = 1;
-    constants.EDGE_VERTICAL = 7;
-
-    constants.FEATURE_ROUNDING = 0;
-    constants.FEATURE_WEB_FLEX_BASIS = 1;
-
-    constants.FLEX_DIRECTION_COLUMN = 0;
-    constants.FLEX_DIRECTION_COLUMN_REVERSE = 1;
-    constants.FLEX_DIRECTION_ROW = 2;
-    constants.FLEX_DIRECTION_ROW_REVERSE = 3;
-
-    constants.JUSTIFY_CENTER = 1;
-    constants.JUSTIFY_FLEX_END = 2;
-    constants.JUSTIFY_FLEX_START = 0;
-    constants.JUSTIFY_SPACE_AROUND = 4;
-    constants.JUSTIFY_SPACE_BETWEEN = 3;
-
-    constants.MEASURE_MODE_UNDEFINED = 0;
-    constants.MEASURE_MODE_EXACTLY = 1;
-    constants.MEASURE_MODE_AT_MOST = 2;
-
-    constants.OVERFLOW_HIDDEN = 1;
-    constants.OVERFLOW_VISIBLE = 0;
-    constants.OVERFLOW_SCROLL = 2;
-
-    constants.POSITION_TYPE_ABSOLUTE = 1;
-    constants.POSITION_TYPE_RELATIVE = 0;
-
-    constants.WRAP_NO_WRAP = 0;
-    constants.WRAP_WRAP = 1;
-
-    constants.UNDEFINED = NaN;
+    }, require(`./YGEnums`));
 
     class Layout {
 
@@ -129,6 +83,80 @@ module.exports = function (bind, lib) {
 
     }
 
+    class Value {
+
+        constructor(unit, value) {
+
+            this.unit = unit;
+            this.value = value;
+
+        }
+
+        fromJS(expose) {
+
+            expose(this.unit, this.value);
+
+        }
+
+        toString() {
+
+            switch (this.unit) {
+
+                case constants.UNIT_PIXEL:
+                    return `${this.value}`;
+
+                case constants.UNIT_PERCENT:
+                    return `${this.value}%`;
+
+                default: {
+                    return `${this.value}?`;
+                }
+
+            }
+
+        }
+
+        valueOf() {
+
+            return this.value;
+
+        }
+
+    }
+
+    for (let fnName of [ `setPosition`, `setMargin`, `setFlexBasis`, `setWidth`, `setHeight`, `setMinWidth`, `setMinHeight`, `setMaxWidth`, `setMaxHeight`, `setPadding` ]) {
+
+        let methods = { [constants.UNIT_PIXEL]: lib.Node.prototype[fnName], [constants.UNIT_PERCENT]: lib.Node.prototype[`${fnName}Percent`] };
+
+        if (Object.keys(methods).some(method => methods[method] == null))
+            throw new Error(`Assertion failed; some unit derivates of ${fnName} seem missing`);
+
+        patch(lib.Node.prototype, fnName, function (original, ... args) {
+
+            // We patch all these functions to add support for the following calls:
+            // .setWidth(100) / .setWidth("100%") / .setWidth(.getWidth())
+
+            let value = args.pop();
+            let unit, asNumber;
+
+            if (value instanceof Value) {
+
+                unit = value.unit;
+                asNumber = value.valueOf();
+
+            } else {
+
+                unit = typeof value === `string` && value.endsWith(`%`) ? constants.UNIT_PERCENT : constants.UNIT_PIXEL;
+                asNumber = parseFloat(value);
+
+            }
+
+            return methods[unit].call(this, ... args, asNumber);
+
+        });
+
+    }
+
     patch(lib.Node.prototype, `free`, function () {
 
         // Since we handle the memory allocation ourselves (via lib.Node.create), we also need to handle the deallocation
@@ -187,6 +215,7 @@ module.exports = function (bind, lib) {
 
     bind(`Layout`, Layout);
     bind(`Size`, Size);
+    bind(`Value`, Value);
 
     return Object.assign({
 
@@ -194,6 +223,7 @@ module.exports = function (bind, lib) {
 
         Layout,
         Size,
+        Value,
 
         setExperimentalFeatureEnabled,
         isExperimentalFeatureEnabled,