From: Lady <redacted>
Date: Mon, 26 Jun 2023 01:54:33 +0000 (-0700)
Subject: Apply various minor updates to binary.js
X-Git-Tag: 0.4.0~3
X-Git-Url: https://git.ladys.computer/Pisces/commitdiff_plain/32ed653b76c0cb255c7ba8f0152740e39d951846?ds=sidebyside;hp=3e02a3609121cc8f06684cc0e38f9b8705099f73

Apply various minor updates to binary.js
---

diff --git a/binary.js b/binary.js
index 686d3a2..f6d8cab 100644
--- a/binary.js
+++ b/binary.js
@@ -55,13 +55,13 @@ const binaryCodeUnitIterablePrototype = {
   },
 };
 
+const { exec: reExec } = rePrototype;
 const getBufferByteLength =
   Object.getOwnPropertyDescriptor(bufferPrototype, "byteLength").get;
 const getTypedArrayBuffer =
   Object.getOwnPropertyDescriptor(typedArrayPrototype, "buffer").get;
 const getViewBuffer =
   Object.getOwnPropertyDescriptor(viewPrototype, "buffer").get;
-const { exec: reExec } = rePrototype;
 const {
   getUint8: viewGetUint8,
   setUint8: viewSetUint8,
@@ -129,10 +129,13 @@ const decodeBase16 = (source) => {
         ? code - 87
         : -1;
       if (result < 0) {
+        // The source contains an invalid character.
         throw new RangeError(
           `Piscēs: Invalid character in Base64: ${ucsCharacter}.`,
         );
       } else {
+        // The source contains a valid character with a recognized
+        // mapping.
         return result;
       }
     },
@@ -148,6 +151,8 @@ const decodeBase16 = (source) => {
     // Every letter contributes at least some bits to the result.
     const dataView = new View(new Buffer(floor(length / 2)));
     for (let index = 0; index < length - 1;) {
+      // Iterate over the characters and assign their bits to the
+      // buffer.
       call(viewSetUint8, dataView, [
         floor(index / 2),
         (u4s[index] << 4) | u4s[++index, index++],
@@ -222,10 +227,13 @@ const decodeBase32 = (source, wrmg) => {
         ? code - 24 // digits 2–7 map to 26–31
         : -1;
       if (result < 0) {
+        // The source contains an invalid character.
         throw new RangeError(
           `Piscēs: Invalid character in Base32: ${ucsCharacter}.`,
         );
       } else {
+        // The source contains a valid character with a recognized
+        // mapping.
         return result;
       }
     },
@@ -242,37 +250,26 @@ const decodeBase32 = (source, wrmg) => {
     // Every letter contributes at least some bits to the result.
     const dataView = new View(new Buffer(floor(length * 5 / 8)));
     for (let index = 0; index < length - 1;) {
+      // Iterate over the characters and assign their bits to the
+      // buffer.
+      //
       // The final index is not handled; if the string is not divisible
       // by 8, some bits might be dropped. This matches the “forgiving
       // decode” behaviour specified by WhatW·G for base64.
       const dataIndex = ceil(index * 5 / 8);
       const remainder = index % 8;
-      if (remainder === 0) {
-        call(viewSetUint8, dataView, [
-          dataIndex,
-          u5s[index] << 3 | u5s[++index] >> 2,
-        ]);
-      } else if (remainder === 1) {
-        call(viewSetUint8, dataView, [
-          dataIndex,
-          u5s[index] << 6 | u5s[++index] << 1 | u5s[++index] >> 4,
-        ]);
-      } else if (remainder === 3) {
-        call(viewSetUint8, dataView, [
-          dataIndex,
-          u5s[index] << 4 | u5s[++index] >> 1,
-        ]);
-      } else if (remainder === 4) {
-        call(viewSetUint8, dataView, [
-          dataIndex,
-          u5s[index] << 7 | u5s[++index] << 2 | u5s[++index] >> 3,
-        ]);
-      } else { // remainder === 6
-        call(viewSetUint8, dataView, [
-          dataIndex,
-          u5s[index] << 5 | u5s[++index, index++],
-        ]);
-      }
+      call(viewSetUint8, dataView, [
+        dataIndex,
+        remainder === 0
+          ? u5s[index] << 3 | u5s[++index] >> 2
+          : remainder === 1
+          ? u5s[index] << 6 | u5s[++index] << 1 | u5s[++index] >> 4
+          : remainder === 3
+          ? u5s[index] << 4 | u5s[++index] >> 1
+          : remainder === 4
+          ? u5s[index] << 7 | u5s[++index] << 2 | u5s[++index] >> 3
+          : u5s[index] << 5 | u5s[++index, index++], // remainder === 6
+      ]);
     }
     return call(getViewBuffer, dataView, []);
   }
@@ -303,10 +300,13 @@ const decodeBase64 = (source, safe = false) => {
         ? 63
         : -1;
       if (result < 0) {
+        // The source contains an invalid character.
         throw new RangeError(
           `Piscēs: Invalid character in Base64: ${ucsCharacter}.`,
         );
       } else {
+        // The source contains a valid character with a recognized
+        // mapping.
         return result;
       }
     },
@@ -322,27 +322,22 @@ const decodeBase64 = (source, safe = false) => {
     // Every letter contributes at least some bits to the result.
     const dataView = new View(new Buffer(floor(length * 3 / 4)));
     for (let index = 0; index < length - 1;) {
+      // Iterate over the characters and assign their bits to the
+      // buffer.
+      //
       // The final index is not handled; if the string is not divisible
       // by 4, some bits might be dropped. This matches the “forgiving
       // decode” behaviour specified by WhatW·G for base64.
       const dataIndex = ceil(index * 3 / 4);
       const remainder = index % 4;
-      if (remainder === 0) {
-        call(viewSetUint8, dataView, [
-          dataIndex,
-          u6s[index] << 2 | u6s[++index] >> 4,
-        ]);
-      } else if (remainder === 1) {
-        call(viewSetUint8, dataView, [
-          dataIndex,
-          u6s[index] << 4 | u6s[++index] >> 2,
-        ]);
-      } else { // remainder === 2
-        call(viewSetUint8, dataView, [
-          dataIndex,
-          u6s[index] << 6 | u6s[++index, index++],
-        ]);
-      }
+      call(viewSetUint8, dataView, [
+        dataIndex,
+        remainder === 0
+          ? u6s[index] << 2 | u6s[++index] >> 4
+          : remainder === 1
+          ? u6s[index] << 4 | u6s[++index] >> 2
+          : u6s[index] << 6 | u6s[++index, index++], // remainder === 2
+      ]);
     }
     return call(getViewBuffer, dataView, []);
   }
@@ -366,17 +361,23 @@ const encodeBase16 = (buffer) => {
     0x3D,
   );
   for (let index = 0; index < byteLength;) {
+    // Iterate over the bytes and generate code units for them.
     const codeUnitIndex = index * 2;
     const datum = call(viewGetUint8, dataView, [index++]);
     const u4s = [datum >> 4, datum & 0xF];
     for (let u4i = 0; u4i < 2; ++u4i) {
+      // Handle the high four bits, then the low four bits.
       const u4 = u4s[u4i];
       const result = u4 < 10 ? u4 + 48 : u4 < 16 ? u4 + 55 : -1;
       if (result < 0) {
+        // No mapping exists for these four bits.
+        //
+        // ※ This shouldn’t be possible!
         throw new RangeError(
           `Piscēs: Unexpected Base16 value: ${u4}.`,
         );
       } else {
+        // A mapping exists for the bits.
         resultingCodeUnits[codeUnitIndex + u4i] = result;
       }
     }
@@ -408,6 +409,7 @@ const encodeBase32 = (buffer, wrmg = false) => {
     fillByte,
   );
   for (let index = 0; index < byteLength;) {
+    // Iterate over the bytes and generate code units for them.
     const codeUnitIndex = ceil(index * 8 / 5);
     const currentIndex = codeUnitIndex + +(
       0b01011 & 1 << index % 5 &&
@@ -457,8 +459,12 @@ const encodeBase32 = (buffer, wrmg = false) => {
       ? u5 + 24
       : -1;
     if (result < 0) {
+      // No mapping exists for these five bits.
+      //
+      // ※ This shouldn’t be possible!
       throw new RangeError(`Piscēs: Unexpected Base32 value: ${u5}.`);
     } else {
+      // A mapping exists for the bits.
       resultingCodeUnits[currentIndex] = result;
     }
   }
@@ -489,6 +495,7 @@ const encodeBase64 = (buffer, safe = false) => {
     0x3D,
   );
   for (let index = 0; index < byteLength;) {
+    // Iterate over the bytes and generate code units for them.
     const codeUnitIndex = ceil(index * 4 / 3);
     const currentIndex = codeUnitIndex + +(
       index % 3 === 0 && resultingCodeUnits[codeUnitIndex] != 0x3D
@@ -518,8 +525,12 @@ const encodeBase64 = (buffer, safe = false) => {
       ? (safe ? 0x5F : 0x2F)
       : -1;
     if (result < 0) {
+      // No mapping exists for these six bits.
+      //
+      // ※ This shouldn’t be possible!
       throw new RangeError(`Piscēs: Unexpected Base64 value: ${u6}.`);
     } else {
+      // A mapping exists for the bits.
       resultingCodeUnits[currentIndex] = result;
     }
   }
@@ -651,8 +662,9 @@ export const isArrayBuffer = ($) => {
     return call(getBufferByteLength, $, []), true;
   } catch {
     // The provided argument does not have array buffer internal slots.
-    return false;
+    /* do nothing */
   }
+  return false;
 };
 
 /**
@@ -663,8 +675,10 @@ export const isArrayBuffer = ($) => {
  */
 export const isBase16 = ($) => {
   if (typeof $ !== "string") {
+    // The provided value is not a string.
     return false;
   } else {
+    // The provided value is a string.
     const source = stringReplace($, /[\t\n\f\r ]+/gu, "");
     return source.length % 2 !== 1 &&
       call(reExec, /[^0-9A-F]/iu, [source]) === null;
@@ -679,8 +693,10 @@ export const isBase16 = ($) => {
  */
 export const isBase32 = ($) => {
   if (typeof $ !== "string") {
+    // The provided value is not a string.
     return false;
   } else {
+    // The provided value is a string.
     const source = stringReplace($, /[\t\n\f\r ]+/gu, "");
     const trimmed = source.length % 8 === 0
       ? stringReplace(source, /(?:=|={3,4}|={6})$/u, "")
@@ -698,8 +714,10 @@ export const isBase32 = ($) => {
  */
 export const isBase64 = ($) => {
   if (typeof $ !== "string") {
+    // The provided value is not a string.
     return false;
   } else {
+    // The provided value is a string.
     const source = stringReplace($, /[\t\n\f\r ]+/gu, "");
     const trimmed = source.length % 4 === 0
       ? stringReplace(source, /={1,2}$/u, "")
@@ -729,8 +747,10 @@ export const isDataView = ($) => {
  */
 export const isFilenameSafeBase64 = ($) => {
   if (typeof $ !== "string") {
+    // The provided value is not a string.
     return false;
   } else {
+    // The provided value is a string.
     const source = stringReplace($, /[\t\n\f\r ]+/gu, "");
     const trimmed = source.length % 4 === 0
       ? stringReplace(source, /={1,2}$/u, "")
@@ -761,8 +781,10 @@ export const isTypedArray = ($) => {
  */
 export const isWRMGBase32 = ($) => {
   if (typeof $ !== "string") {
+    // The provided value is not a string.
     return false;
   } else {
+    // The provided value is a string.
     const source = stringReplace($, /[\t\n\f\r ]+/gu, "");
     const trimmed = stringReplace(source, /-/gu, "");
     return trimmed.length % 8 !== 1 &&
@@ -777,19 +799,25 @@ export const isWRMGBase32 = ($) => {
  * typed array.
  */
 export const toArrayBuffer = ($) => {
-  try {
+  if (isArrayBuffer($)) {
     // The provided argument has array buffer internal slots.
-    return call(getBufferByteLength, $, []), $;
-  } catch {}
-  try {
-    // The provided argument has typed array internal slots.
-    return call(getTypedArrayBuffer, $, []);
-  } catch {}
-  try {
-    // The provided argument has data view internal slots.
-    return call(getViewBuffer, $, []);
-  } catch {}
-  throw new TypeError(`Piscēs: Not an array buffer or view: ${$}.`);
+    return $;
+  } else {
+    // The provided argument does not have array buffer internal slots.
+    try {
+      // The provided argument has typed array internal slots.
+      return call(getTypedArrayBuffer, $, []);
+    } catch {
+      /* do nothing */
+    }
+    try {
+      // The provided argument has data view internal slots.
+      return call(getViewBuffer, $, []);
+    } catch {
+      /* do nothing */
+    }
+    throw new TypeError(`Piscēs: Not an array buffer or view: ${$}.`);
+  }
 };
 
 /**