fix(issue:3777) improve custom property initial

* Improves CSS custom property initial value support, including nesting
  scenarios to better address issue less#3777.

Author: puckowski

packages/less/src/less/functions/math-helper.js

@@ -4,8 +4,8 @@ import Dimension from '../tree/dimension';
 
 const MathHelper = (fn, unit, n) => {
     if (n instanceof Call && n.name === 'var') {
-        if (n.args && n.args.length === 1) {
-            return new Call(fn.name, [new CustomProperty(n.args[0].toCSS(), n._index, n._fileInfo)], n._index, n._fileInfo);
+        if (n.args && n.args.length >= 1) {
+            return new Call(fn.name, [new CustomProperty(n.args[0].toCSS(), n.args[1] ? n.args[1].toCSS() : null, n._index, n._fileInfo)], n._index, n._fileInfo);
         } else {
             throw { type: 'Argument', message: 'var must contain one expression' };
         }

packages/less/src/less/functions/number.js

@@ -1,6 +1,7 @@
 import Dimension from '../tree/dimension';
 import Anonymous from '../tree/anonymous';
 import mathHelper from './math-helper.js';
+import Call from '../tree/call';
 
 const minMax = function (isMin, args) {
     args = Array.prototype.slice.call(args);
@@ -78,6 +79,10 @@ export default {
         return new Dimension(a.value % b.value, a.unit);
     },
     pow: function(x, y) {
+        if (x instanceof Call || y instanceof Call) {
+            // Must return Node
+            return new Anonymous(x.toCSS() + ', ' + y.toCSS());
+        }
         if (typeof x === 'number' && typeof y === 'number') {
             x = new Dimension(x);
             y = new Dimension(y);

packages/less/src/less/tree/call.js

@@ -1,6 +1,7 @@
 import Node from './node';
 import Anonymous from './anonymous';
 import FunctionCaller from '../functions/function-caller';
+import CustomProperty from './custom-property';
 
 //
 // A function call node.
@@ -98,11 +99,34 @@ Call.prototype = Object.assign(new Node(), {
 
     genCSS(context, output) {
         output.add(`${this.name}(`, this.fileInfo(), this.getIndex());
+        let isCustomProperty = false;
+        let customExpressionCount = 0;
 
         for (let i = 0; i < this.args.length; i++) {
             this.args[i].genCSS(context, output);
+            
+            if (this.args[i] instanceof CustomProperty
+                || ((i + 2 < this.args.length && this.args[i + 2] instanceof CustomProperty))) {
+                if (isCustomProperty) {
+                    isCustomProperty = false;
+                } else {
+                    isCustomProperty = true;
+                    customExpressionCount = 1;
+                }
+            }
+
+            if (customExpressionCount === 3) {
+                isCustomProperty = false;
+                customExpressionCount = 0;
+            }
+            
             if (i + 1 < this.args.length) {
-                output.add(', ');
+                if (!isCustomProperty) {
+                    output.add(', ');
+                } else {
+                    output.add(' ');
+                    customExpressionCount++;
+                }
             }
         }
 

packages/less/src/less/tree/custom-property.js

@@ -1,8 +1,9 @@
 /* eslint-disable no-prototype-builtins */
 import Node from './node';
 
-const CustomProperty = function (name, index, currentFileInfo) {
+const CustomProperty = function (name, initialValue, index, currentFileInfo) {
     this.name = name;
+    this.initialValue = initialValue;
     this._index = index;
     this._fileInfo = currentFileInfo;
 };
@@ -11,7 +12,7 @@ CustomProperty.prototype = Object.assign(new Node(), {
     type: 'CustomProperty',
 
     genCSS: function (context, output) {
-        output.add('var(' + this.name + ')');
+        output.add('var(' + this.name + (this.initialValue ? ', ' + this.initialValue : '') + ')');
     }
 });
 

packages/less/src/less/tree/operation.js

@@ -3,6 +3,8 @@ import Color from './color';
 import Dimension from './dimension';
 import * as Constants from '../constants';
 import Call from './call';
+import CustomProperty from './custom-property';
+import Anonymous from './anonymous';
 const MATH = Constants.Math;
 
 
@@ -38,6 +40,12 @@ Operation.prototype = Object.assign(new Node(), {
             if (b instanceof Dimension && a instanceof Color) {
                 b = b.toColor();
             }
+            if (a instanceof Dimension && b instanceof CustomProperty) {
+                return [a, new Anonymous(op), b];
+            }
+            if (b instanceof Dimension && a instanceof CustomProperty) {
+                return [a, new Anonymous(op), b];
+            }
             if (!a.operate || !b.operate) {
                 if (
                     (a instanceof Operation || b instanceof Operation)
@@ -78,7 +86,7 @@ Operation.prototype = Object.assign(new Node(), {
     },
 
     evalVariable: function (context, operand) {
-        if (operand.name === 'var' && operand.args.length === 1) {
+        if (operand.name === 'var' && operand.args.length >= 1) {
             var varName = operand.args[0].toCSS();
             var variable = this.find(context.frames, function (frame) {
                 var v = frame.variable(varName);
@@ -92,7 +100,7 @@ Operation.prototype = Object.assign(new Node(), {
                         return (new Call('_SELF', [v.value])).eval(context);
                     }
                     else {
-                        return v.value.eval(context);
+                        return new CustomProperty(v.name, operand.args[1] ? operand.args[1].toCSS() : null, 0, {});
                     }
                 }
             });

packages/test-data/css/_main/custom-property.css

@@ -4,13 +4,21 @@
 }
 .test2 {
   --some-var: 5%;
-  prop: min(95%, 10px);
+  prop: min(100% - var(--some-var), 10px);
 }
 .test3 {
   --some-var: 55%;
-  prop: min(60%, 15px);
+  prop: min(var(--some-var) + 5%, 15px);
 }
 .test4 {
   color: red;
   --other-color: green;
 }
+.test5 {
+  --font-level: 5;
+  prop: var(--font-ratio-min), var(--font-level, 0);
+}
+.test6 {
+  --some-var: 5px;
+  prop: min(100% - var(--some-var, var(--somevar, 0)), 10px);
+}

packages/test-data/less/_main/custom-property.less

@@ -17,3 +17,14 @@
     color: red;
     --other-color: green;
 }
+
+.test5 {
+    --font-level: 5;
+    prop: pow(var(--font-ratio-min), var(--font-level, 0))
+}
+
+
+.test6 {
+    --some-var: 5px;
+    prop: min(100% - var(--some-var, var(--somevar, 0)), 10px);
+}