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feat(loader): use TextDecoder for large strings #1471

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Merged
merged 7 commits into from
Sep 27, 2020
Merged

feat(loader): use TextDecoder for large strings #1471

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7343ed0
feat(loader): use TextDecoder for large strings
MaxGraey Sep 25, 2020
22bc157
node.js as well
MaxGraey Sep 25, 2020
7326bc9
fix
MaxGraey Sep 25, 2020
2a5ddea
revert
MaxGraey Sep 25, 2020
5be9ad3
' -> "
MaxGraey Sep 25, 2020
7b61d73
add test
MaxGraey Sep 25, 2020
03e3e5e
simplify
MaxGraey Sep 25, 2020
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30 changes: 18 additions & 12 deletions lib/loader/index.js
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Original file line number Diff line number Diff line change
Expand Up @@ -38,23 +38,29 @@ const ARRAY_SIZE = 16;

const BIGINT = typeof BigUint64Array !== "undefined";
const THIS = Symbol();
const CHUNKSIZE = 1024;

const STRING_DECODE_THRESHOLD = 32;

let decoder;
if (typeof process !== 'undefined') {
// node.js
decoder = new (require('util').TextDecoder)('utf-16le');
} else {
// browser
decoder = new TextDecoder('utf-16le');
}

/** Gets a string from an U32 and an U16 view on a memory. */
function getStringImpl(buffer, ptr) {
const U32 = new Uint32Array(buffer);
const U16 = new Uint16Array(buffer);
let length = U32[ptr + SIZE_OFFSET >>> 2] >>> 1;
let offset = ptr >>> 1;
if (length <= CHUNKSIZE) return String.fromCharCode.apply(String, U16.subarray(offset, offset + length));
let parts = '';
do {
const last = U16[offset + CHUNKSIZE - 1];
const size = last >= 0xD800 && last < 0xDC00 ? CHUNKSIZE - 1 : CHUNKSIZE;
parts += String.fromCharCode.apply(String, U16.subarray(offset, offset += size));
length -= size;
} while (length > CHUNKSIZE);
return parts + String.fromCharCode.apply(String, U16.subarray(offset, offset + length));
const length = U32[ptr + SIZE_OFFSET >>> 2] >>> 1;
const offset = ptr >>> 1;
const data = U16.subarray(offset, offset + length);
if (length <= STRING_DECODE_THRESHOLD) {
return String.fromCharCode.apply(String, data);
}
return decoder.decode(data);
}

/** Prepares the base module prior to instantiation. */
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