Add clamping functions to FixedNumber (#1037).

packages/bignumber/src.ts/fixednumber.ts

@@ -240,29 +240,56 @@ export class FixedNumber {
         return FixedNumber.fromValue(a.mul(this.format._multiplier).div(b), this.format.decimals, this.format);
     }
 
+    floor(): FixedNumber {
+        let comps = this.toString().split(".");
+
+        let result = FixedNumber.from(comps[0], this.format);
+
+        const hasFraction = !comps[1].match(/^(0*)$/);
+        if (this.isNegative() && hasFraction) {
+            result = result.subUnsafe(ONE);
+        }
+
+        return result;
+    }
+
+    ceiling(): FixedNumber {
+        let comps = this.toString().split(".");
+
+        let result = FixedNumber.from(comps[0], this.format);
+
+        const hasFraction = !comps[1].match(/^(0*)$/);
+        if (!this.isNegative() && hasFraction) {
+            result = result.addUnsafe(ONE);
+        }
+
+        return result;
+    }
+
     // @TODO: Support other rounding algorithms
     round(decimals?: number): FixedNumber {
         if (decimals == null) { decimals = 0; }
+
+        // If we are already in range, we're done
+        let comps = this.toString().split(".");
+
         if (decimals < 0 || decimals > 80 || (decimals % 1)) {
             logger.throwArgumentError("invalid decimal count", "decimals", decimals);
         }
 
-        // If we are already in range, we're done
-        let comps = this.toString().split(".");
         if (comps[1].length <= decimals) { return this; }
 
-        // Bump the value up by the 0.00...0005
-        const bump = "0." + zeros.substring(0, decimals) + "5";
-        comps = this.addUnsafe(FixedNumber.fromString(bump, this.format))._value.split(".");
-
-        // Now it is safe to truncate
-        return FixedNumber.fromString(comps[0] + "." + comps[1].substring(0, decimals));
+        const factor = FixedNumber.from("1" + zeros.substring(0, decimals));
+        return this.mulUnsafe(factor).addUnsafe(BUMP).floor().divUnsafe(factor);
     }
 
     isZero(): boolean {
         return (this._value === "0.0");
     }
 
+    isNegative(): boolean {
+        return (this._value[0] === "-");
+    }
 
     toString(): string { return this._value; }
 
@@ -361,3 +388,6 @@ export class FixedNumber {
         return !!(value && value._isFixedNumber);
     }
 }
+
+const ONE = FixedNumber.from(1);
+const BUMP = FixedNumber.from("0.5");

packages/tests/src.ts/test-utils.ts

@@ -623,6 +623,80 @@ describe("BigNumber", function() {
 
 });
 
+
+describe("FixedNumber", function() {
+    {
+        const Tests = [
+            { value: "0.0",    expected: "0.0"  },
+            { value: "-0.0",   expected: "0.0"  },
+
+            { value: "1.0",    expected: "1.0"  },
+            { value: "1.00",   expected: "1.0"  },
+            { value: "01.00",  expected: "1.0"  },
+            { value: 1,        expected: "1.0"  },
+
+            { value: "-1.0",   expected: "-1.0"  },
+            { value: "-1.00",  expected: "-1.0"  },
+            { value: "-01.00", expected: "-1.0"  },
+            { value: -1,       expected: "-1.0"  },
+        ];
+
+        Tests.forEach((test) => {
+            it (`Create from=${ test.value }`, function() {
+                const value = ethers.FixedNumber.from(test.value);
+                assert.equal(value.toString(), test.expected);
+            });
+        });
+    }
+
+    {
+        const Tests = [
+            { value: "1.0",    round: 1,   expected: "1.0"  },
+            { value: "1.4",    round: 1,   expected: "1.4"  },
+            { value: "1.4",    round: 2,   expected: "1.4"  },
+            { value: "1.4",    round: 0,   expected: "1.0"  },
+            { value: "1.5",    round: 0,   expected: "2.0"  },
+            { value: "1.6",    round: 0,   expected: "2.0"  },
+
+            { value: "-1.0",   round: 1,   expected: "-1.0" },
+            { value: "-1.4",   round: 1,   expected: "-1.4" },
+            { value: "-1.4",   round: 2,   expected: "-1.4" },
+            { value: "-1.4",   round: 0,   expected: "-1.0" },
+            { value: "-1.5",   round: 0,   expected: "-1.0" },
+            { value: "-1.6",   round: 0,   expected: "-2.0" },
+
+            { value: "1.51",   round: 1,   expected: "1.5"  },
+            { value: "1.55",   round: 1,   expected: "1.6"  },
+        ];
+
+        Tests.forEach((test) => {
+            it (`Rounding value=${ test.value }, decimals=${ test.round }`, function() {
+                const value = ethers.FixedNumber.from(test.value).round(test.round);
+                assert.equal(value.toString(), test.expected);
+            });
+        });
+    }
+
+    {
+        const Tests = [
+            { value: "1.0",   ceiling: "1.0",   floor: "1.0"  },
+            { value: "1.1",   ceiling: "2.0",   floor: "1.0"  },
+            { value: "1.9",   ceiling: "2.0",   floor: "1.0"  },
+            { value: "-1.0",  ceiling: "-1.0",  floor: "-1.0" },
+            { value: "-1.1",  ceiling: "-1.0",  floor: "-2.0" },
+            { value: "-1.9",  ceiling: "-1.0",  floor: "-2.0" },
+        ];
+
+        Tests.forEach((test) => {
+            it (`Clamping value=${ test.value }`, function() {
+                const value = ethers.FixedNumber.from(test.value);
+                assert.equal(value.floor().toString(), test.floor);
+                assert.equal(value.ceiling().toString(), test.ceiling);
+            });
+        });
+    }
+});
+
 describe("Logger", function() {
     const logger = new ethers.utils.Logger("testing/0.0");
 
@@ -658,7 +732,6 @@ describe("Logger", function() {
     });
 });
 
-
 /*
 describe("Base58 Coder", function() {
     it("decodes", function() {