A POC that replaces all BigInt to JSBI.BigInt (#101)

jessealama · Nov 19, 2024 · fc0e300 · fc0e300
1 parent 094a0f7
commit fc0e300
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Showing 11 changed files with 161 additions and 114 deletions.
diff --git a/package-lock.json b/package-lock.json
diff --git a/package.json b/package.json
@@ -45,6 +45,9 @@
     ],
     "author": "Jesse Alama <jesse@igalia.com>",
     "license": "ISC",
+    "dependencies": {
+        "jsbi": "^4.3.0"
+    },
     "devDependencies": {
         "@rollup/plugin-typescript": "^12.1.1",
         "@types/jest": "^29.5.1",

diff --git a/src/Decimal.mts b/src/Decimal.mts
@@ -1,3 +1,4 @@
+import JSBI from "jsbi";
 import { Rational } from "./Rational.mjs";
 
 function _cohort(s: string): "0" | "-0" | Rational {
@@ -88,7 +89,7 @@ export class Decimal {
         });
     }
 
-    public coefficient(): bigint {
+    public coefficient(): JSBI {
         let v = this.cohort as Rational;
         let q = this.quantum;
         let c = v.scale10(0 - q);

diff --git a/src/Decimal128.mts b/src/Decimal128.mts
@@ -13,6 +13,8 @@
  * @author Jesse Alama <jesse@igalia.com>
  */
 
+import JSBI from "jsbi";
+
 import {
     RoundingMode,
     ROUNDING_MODES,
@@ -28,7 +30,7 @@ const EXPONENT_MAX = 6111;
 const NORMAL_EXPONENT_MAX = 6144;
 const MAX_SIGNIFICANT_DIGITS = 34;
 
-const bigTen = BigInt(10);
+const bigTen = JSBI.BigInt(10);
 
 type NaNValue = "NaN";
 type InfiniteValue = "Infinity" | "-Infinity";
@@ -39,7 +41,7 @@ type Decimal128Value = NaNValue | InfiniteValue | FiniteValue;
 const NAN = "NaN";
 const POSITIVE_INFINITY = "Infinity";
 const NEGATIVE_INFINITY = "-Infinity";
-const TEN_MAX_EXPONENT = bigTen ** BigInt(MAX_SIGNIFICANT_DIGITS);
+const TEN_MAX_EXPONENT = JSBI.exponentiate(bigTen, JSBI.BigInt(MAX_SIGNIFICANT_DIGITS));
 
 function pickQuantum(
     d: "0" | "-0" | Rational,
@@ -80,7 +82,7 @@ function adjustDecimal128(d: Decimal): Decimal128Value {
 
     let coef = d.coefficient();
 
-    if (coef <= TEN_MAX_EXPONENT && EXPONENT_MIN <= q && q <= EXPONENT_MAX) {
+    if (JSBI.LE(coef, TEN_MAX_EXPONENT) && JSBI.LE(EXPONENT_MIN, q) && JSBI.LE(q, EXPONENT_MAX)) {
         return d;
     }
 
@@ -166,10 +168,18 @@ export class Decimal128 {
     private readonly _isFinite: boolean = true;
     private readonly _isNegative: boolean = false;
 
-    constructor(n: string | number | bigint | Decimal) {
+    constructor(n: string | number | bigint | JSBI | Decimal) {
         let data;
         if ("object" === typeof n) {
-            data = n;
+            if (n instanceof JSBI) {
+                // Note: when using babel-plugin-transform-jsbi-to-bigint,
+                // the condition above may get transpiled into "typeof n === 'bigint'",
+                // causing the condition above to always be false.
+                // This is fine as we will be hanlding bigint below.
+                data = handleDecimalNotation(n.toString())
+            } else {
+                data = n;
+            }
         } else {
             let s: string;
 
@@ -262,7 +272,7 @@ export class Decimal128 {
         let decimalOne = new Decimal128("1");
         let decimalTen = new Decimal128("10");
 
-        while (0 <= x.cmp(decimalTen)) {
+        while (JSBI.LE(0, x.cmp(decimalTen))) {
             x = x.scale10(-1);
         }
 
@@ -303,7 +313,7 @@ export class Decimal128 {
         );
     }
 
-    private coefficient(): bigint {
+    private coefficient(): JSBI {
         let d = this.d as Decimal;
         return d.coefficient();
     }
@@ -463,7 +473,7 @@ export class Decimal128 {
 
         let n = opts.digits;
 
-        if (n <= 0) {
+        if (JSBI.LE(n, 0)) {
             throw new RangeError("Argument must be positive");
         }
 
@@ -484,15 +494,15 @@ export class Decimal128 {
         let [lhs, rhs] = s.split(/[.]/);
         let p = this.isNegative() ? "-" : "";
 
-        if (n <= lhs.length) {
+        if (JSBI.LE(n, lhs.length)) {
             if (lhs.length === n) {
                 return p + lhs;
             }
 
             return p + s.substring(0, n) + "e+" + `${lhs.length - n + 1}`;
         }
 
-        if (n <= lhs.length + rhs.length) {
+        if (JSBI.LE(n, lhs.length + rhs.length)) {
             let rounded = this.round(n - lhs.length);
             return rounded.emitDecimal();
         }
@@ -523,7 +533,7 @@ export class Decimal128 {
 
         let n = opts.digits;
 
-        if (n <= 0) {
+        if (JSBI.LE(n, 0)) {
             throw new RangeError("Argument must be positive");
         }
 
@@ -539,7 +549,7 @@ export class Decimal128 {
 
         let p = this.isNegative() ? "-" : "";
 
-        if (rhs.length <= n) {
+        if (JSBI.LE(rhs.length, n)) {
             return p + lhs + "." + rhs + "0".repeat(n - rhs.length) + "e" + exp;
         }
 
@@ -558,7 +568,7 @@ export class Decimal128 {
         return !!rhs.match(/^0+$/);
     }
 
-    toBigInt(): bigint {
+    toBigInt(): JSBI {
         if (this.isNaN()) {
             throw new RangeError("NaN cannot be converted to a BigInt");
         }
@@ -573,7 +583,7 @@ export class Decimal128 {
             );
         }
 
-        return BigInt(this.toString());
+        return JSBI.BigInt(this.toString());
     }
 
     toNumber(): number {
@@ -931,34 +941,34 @@ export class Decimal128 {
         let dividendCoefficient = this.coefficient();
         let divisorCoefficient = x.coefficient();
 
-        if (dividendCoefficient !== 0n) {
-            while (dividendCoefficient < divisorCoefficient) {
-                dividendCoefficient = dividendCoefficient * 10n;
+        if (JSBI.notEqual(dividendCoefficient, JSBI.BigInt(0))) {
+            while (JSBI.LT(dividendCoefficient, divisorCoefficient)) {
+                dividendCoefficient = JSBI.multiply(dividendCoefficient, JSBI.BigInt(10));
                 adjust++;
             }
         }
 
-        while (dividendCoefficient > divisorCoefficient * 10n) {
-            divisorCoefficient = divisorCoefficient * 10n;
+        while (JSBI.GT(dividendCoefficient, JSBI.multiply(divisorCoefficient, JSBI.BigInt(10)))) {
+            divisorCoefficient = JSBI.multiply(divisorCoefficient, JSBI.BigInt(10));
             adjust--;
         }
 
-        let resultCoefficient = 0n;
+        let resultCoefficient = JSBI.BigInt(0);
         let done = false;
 
         while (!done) {
-            while (divisorCoefficient <= dividendCoefficient) {
-                dividendCoefficient = dividendCoefficient - divisorCoefficient;
-                resultCoefficient++;
+            while (JSBI.LE(divisorCoefficient, dividendCoefficient)) {
+                dividendCoefficient = JSBI.subtract(dividendCoefficient, divisorCoefficient);
+                resultCoefficient = JSBI.add(resultCoefficient, JSBI.BigInt(1));
             }
             if (
-                (dividendCoefficient === 0n && adjust >= 0) ||
+                (JSBI.equal(dividendCoefficient, JSBI.BigInt(0)) && adjust >= 0) ||
                 resultCoefficient.toString().length > MAX_SIGNIFICANT_DIGITS
             ) {
                 done = true;
             } else {
-                resultCoefficient = resultCoefficient * 10n;
-                dividendCoefficient = dividendCoefficient * 10n;
+                resultCoefficient = JSBI.multiply(resultCoefficient, JSBI.BigInt(10));
+                dividendCoefficient = JSBI.multiply(dividendCoefficient, JSBI.BigInt(10));
                 adjust++;
             }
         }
@@ -1123,7 +1133,7 @@ export class Decimal128 {
         return this.exponent();
     }
 
-    scaledSignificand(): bigint {
+    scaledSignificand(): JSBI {
         if (this.isNaN()) {
             throw new RangeError("NaN does not have a scaled significand");
         }
@@ -1133,7 +1143,7 @@ export class Decimal128 {
         }
 
         if (this.isZero()) {
-            return 0n;
+            return JSBI.BigInt(0);
         }
 
         let v = this.cohort() as Rational;