From c04505f3eab96763af47d210728ae41039909524 Mon Sep 17 00:00:00 2001
From: Lumi Pakkanen <lumi.pakkanen@gmail.com>
Date: Thu, 21 Dec 2023 10:35:33 +0200
Subject: [PATCH] Rely on Fraction throwing behaviour to deal with unsafe
 fractions

---
 src/__tests__/scale.spec.ts | 13 ++++++++++
 src/interval.ts             | 49 +++++++++++++++++--------------------
 src/scale.ts                |  1 +
 src/utils.ts                | 12 ---------
 4 files changed, 36 insertions(+), 39 deletions(-)

diff --git a/src/__tests__/scale.spec.ts b/src/__tests__/scale.spec.ts
index bda1536..e2e9a0c 100644
--- a/src/__tests__/scale.spec.ts
+++ b/src/__tests__/scale.spec.ts
@@ -558,6 +558,19 @@ describe('Scale', () => {
     expect(scale.size).toBe(14);
   });
 
+  it('can generate rank 2 (unsafe fractions)', () => {
+    const generator = new Interval(
+      ExtendedMonzo.fromFraction('11/7', 5),
+      'ratio'
+    );
+    const octave = new Interval(ExtendedMonzo.fromFraction(2, 5), 'ratio');
+    const scale = Scale.fromRank2(generator, octave, 100, 0);
+    // Expect not to raise.
+    for (let i = 0; i < 100; ++i) {
+      scale.getName(i);
+    }
+  });
+
   it('can generate harmonic series segment', () => {
     const scale = Scale.fromHarmonicSeries(4, 8, 4);
     expect(
diff --git a/src/interval.ts b/src/interval.ts
index 9078002..257bd31 100644
--- a/src/interval.ts
+++ b/src/interval.ts
@@ -1,5 +1,5 @@
 import {ExtendedMonzo} from './monzo';
-import {fractionToString, isSafeFraction} from './utils';
+import {fractionToString} from './utils';
 import {Fraction} from 'xen-dev-utils';
 
 /** Interval formatting options. */
@@ -502,8 +502,8 @@ export class Interval {
       maybeFraction.cents = 0;
 
       if (maybeFraction.isFractional()) {
-        const fraction = maybeFraction.toFraction();
-        if (isSafeFraction(fraction)) {
+        try {
+          const fraction = maybeFraction.toFraction();
           return (
             fractionToString(
               fraction,
@@ -511,9 +511,10 @@ export class Interval {
               options.preferredDenominator
             ) + this.centsString(true)
           );
-        }
-        if (options.forbidMonzo) {
-          return cents();
+        } catch {
+          if (options.forbidMonzo) {
+            return cents();
+          }
         }
       }
     }
@@ -523,8 +524,8 @@ export class Interval {
       maybeEt.cents = 0;
 
       if (maybeEt.isEqualTemperament()) {
-        const [fractionOfEquave, equave] = maybeEt.toEqualTemperament();
-        if (isSafeFraction(fractionOfEquave) && isSafeFraction(equave)) {
+        try {
+          maybeEt.toEqualTemperament();
           const et = new Interval(
             maybeEt,
             'equal temperament',
@@ -532,9 +533,10 @@ export class Interval {
             this.options
           );
           return et.equalTemperamentString() + this.centsString(true);
-        }
-        if (options.forbidMonzo) {
-          return cents();
+        } catch {
+          if (options.forbidMonzo) {
+            return cents();
+          }
         }
       }
     }
@@ -547,22 +549,15 @@ export class Interval {
       if (options.forbidComposite) {
         return cents();
       }
-      if (isSafeFraction(this.monzo.residual)) {
-        if (this.type === 'monzo') {
-          console.warn('Failed to represent monzo. Displaying residue.');
-        }
-        return (
-          this.monzoString() +
-          ' + ' +
-          fractionToString(
-            this.monzo.residual,
-            options.preferredNumerator,
-            options.preferredDenominator
-          )
-        );
-      } else {
-        return cents();
-      }
+      return (
+        this.monzoString() +
+        ' + ' +
+        fractionToString(
+          this.monzo.residual,
+          options.preferredNumerator,
+          options.preferredDenominator
+        )
+      );
     }
     if (options.forbidComposite) {
       return cents();
diff --git a/src/scale.ts b/src/scale.ts
index c438feb..e300088 100644
--- a/src/scale.ts
+++ b/src/scale.ts
@@ -167,6 +167,7 @@ export class Scale {
       period = period.mergeOptions(options);
       if (
         period.type === 'ratio' &&
+        period.monzo.isFractional() &&
         period.monzo.toFraction().mod(genEquave).equals(0)
       ) {
         period.type = 'equal temperament';
diff --git a/src/utils.ts b/src/utils.ts
index 3e3a665..989b498 100644
--- a/src/utils.ts
+++ b/src/utils.ts
@@ -1,17 +1,5 @@
 import {Fraction} from 'xen-dev-utils';
 
-/**
- * Check if the fraction exactly representable as a `Number`.
- * @param fraction Input fraction.
- * @returns `true` if both numerator, numerator + 1, denominator and denominator + 1 are exactly representable.
- */
-export function isSafeFraction(fraction: Fraction) {
-  return (
-    fraction.n <= Number.MAX_SAFE_INTEGER &&
-    fraction.d <= Number.MAX_SAFE_INTEGER
-  );
-}
-
 /**
  * Convert fraction to a string.
  * @param fraction Input fraction.