#101 Add clamp method

decimal.mjs

@@ -127,6 +127,7 @@ var EXP_LIMIT = 9e15,                      // 0 to 9e15
 /*
  *  absoluteValue             abs
  *  ceil
+ *  clampedTo                 clamp                                   
  *  comparedTo                cmp
  *  cosine                    cos
  *  cubeRoot                  cbrt
@@ -208,6 +209,26 @@ P.ceil = function () {
 };
 
 
+/*
+ * Return a new Decimal whose value is the value of this Decimal clamped to the range
+ * delineated by `min` and `max`.
+ *
+ * min {number|string|Decimal}
+ * max {number|string|Decimal}
+ *
+ */
+P.clampedTo = P.clamp = function (min, max) {
+  var k,
+    x = this,
+    Ctor = x.constructor;
+  min = new Ctor(min);
+  max = new Ctor(max);
+  if (!min.s || !max.s || min.gt(max)) return new Ctor(NaN);
+  k = x.cmp(min);
+  return k < 0 ? min : x.cmp(max) > 0 ? max : new Ctor(x);
+};
+
+
 /*
  * Return
  *   1    if the value of this Decimal is greater than the value of `y`,
@@ -2441,18 +2462,6 @@ P.valueOf = P.toJSON = function () {
 };
 
 
-/*
-// Add aliases to match BigDecimal method names.
-// P.add = P.plus;
-P.subtract = P.minus;
-P.multiply = P.times;
-P.divide = P.div;
-P.remainder = P.mod;
-P.compareTo = P.cmp;
-P.negate = P.neg;
- */
-
-
 // Helper functions for Decimal.prototype (P) and/or Decimal methods, and their callers.
 
 
@@ -3930,6 +3939,7 @@ function truncate(arr, len) {
  *  atan2
  *  cbrt
  *  ceil
+ *  clamp         
  *  clone
  *  config
  *  cos
@@ -4149,6 +4159,19 @@ function ceil(x) {
 }
 
 
+/*
+ * Return a new Decimal whose value is `x` clamped to the range delineated by `min` and `max`.
+ *
+ * x {number|string|Decimal}
+ * min {number|string|Decimal}
+ * max {number|string|Decimal}
+ *
+ */
+function clamp(x, min, max) {
+  return new this(x).clamp(min, max);
+}
+
+
 /*
  * Configure global settings for a Decimal constructor.
  *
@@ -4382,6 +4405,7 @@ function clone(obj) {
   Decimal.atan2 = atan2;
   Decimal.cbrt = cbrt;          // ES6
   Decimal.ceil = ceil;
+  Decimal.clamp = clamp;                      
   Decimal.cos = cos;
   Decimal.cosh = cosh;          // ES6
   Decimal.div = div;