Sqrt calc function implementation

lib/src/ast/sass/expression/calculation.dart

@@ -50,6 +50,10 @@ class CalculationExpression implements Expression {
     }
   }
 
+  /// Returns a `sqrt()` calculation expression.
+  CalculationExpression.sqrt(Expression argument, FileSpan span)
+      : this("sqrt", [argument], span);
+
   /// Returns a `clamp()` calculation expression.
   CalculationExpression.clamp(
       Expression min, Expression value, Expression max, FileSpan span)

lib/src/parse/stylesheet.dart

@@ -2894,6 +2894,7 @@ abstract class StylesheetParser extends Parser {
     assert(scanner.peekChar() == $lparen);
     switch (name) {
       case "calc":
+      case "sqrt":
         var arguments = _calculationArguments(1);
         return CalculationExpression(name, arguments, scanner.spanFrom(start));
 

lib/src/value/calculation.dart

@@ -11,6 +11,7 @@ import '../utils.dart';
 import '../value.dart';
 import '../visitor/interface/value.dart';
 import '../visitor/serialize.dart';
+import 'dart:math' as math;
 
 /// A SassScript calculation.
 ///
@@ -120,6 +121,25 @@ class SassCalculation extends Value {
     return SassCalculation._("max", args);
   }
 
+  /// Creates a `sqrt()` calculation with the given [argument].
+  ///
+  /// Each argument must be either a [SassNumber], a [SassCalculation], an
+  /// unquoted [SassString], a [CalculationOperation], or a
+  /// [CalculationInterpolation]. It must be passed at least one argument.
+  ///
+  /// This automatically simplifies the calculation, so it may return a
+  /// [SassNumber] rather than a [SassCalculation]. It throws an exception if it
+  /// can determine that the calculation will definitely produce invalid CSS.
+  static Value sqrt(Object argument) {
+    argument = _simplify(argument);
+    if (argument is! SassNumber) {
+      return SassCalculation.sqrt(argument);
+    }
+    argument.assertNoUnits();
+
+    return SassNumber(math.sqrt(argument.value));
+  }
+
   /// Creates a `clamp()` calculation with the given [min], [value], and [max].
   ///
   /// Each argument must be either a [SassNumber], a [SassCalculation], an

lib/src/visitor/async_evaluate.dart

@@ -2292,7 +2292,7 @@ class _EvaluateVisitor
     var arguments = [
       for (var argument in node.arguments)
         await _visitCalculationValue(argument,
-            inMinMax: node.name == 'min' || node.name == 'max')
+            inMinMax: {'min', 'max', 'sqrt'}.contains(node.name))
     ];
     if (_inSupportsDeclaration) {
       return SassCalculation.unsimplified(node.name, arguments);
@@ -2303,6 +2303,9 @@ class _EvaluateVisitor
         case "calc":
           assert(arguments.length == 1);
           return SassCalculation.calc(arguments[0]);
+        case "sqrt":
+          assert(arguments.length == 1);
+          return SassCalculation.sqrt(arguments[0]);
         case "min":
           return SassCalculation.min(arguments);
         case "max":