next
Version:
The React Framework
56 lines (55 loc) • 1.94 kB
JavaScript
/**
* Find the starting index of Uint8Array `b` within Uint8Array `a`.
*/ export function indexOfUint8Array(a, b) {
if (b.length === 0) return 0;
if (a.length === 0 || b.length > a.length) return -1;
// Use Node's native implementation when available.
if (typeof Buffer !== 'undefined') {
const haystack = Buffer.isBuffer(a) ? a : Buffer.from(a.buffer, a.byteOffset, a.byteLength);
return haystack.indexOf(b);
}
// start iterating through `a`
for(let i = 0; i <= a.length - b.length; i++){
let completeMatch = true;
// from index `i`, iterate through `b` and check for mismatch
for(let j = 0; j < b.length; j++){
// if the values do not match, then this isn't a complete match, exit `b` iteration early and iterate to next index of `a`.
if (a[i + j] !== b[j]) {
completeMatch = false;
break;
}
}
if (completeMatch) {
return i;
}
}
return -1;
}
/**
* Check if two Uint8Arrays are strictly equivalent.
*/ export function isEquivalentUint8Arrays(a, b) {
if (a.length !== b.length) return false;
for(let i = 0; i < a.length; i++){
if (a[i] !== b[i]) return false;
}
return true;
}
/**
* Remove Uint8Array `b` from Uint8Array `a`.
*
* If `b` is not in `a`, `a` is returned unchanged.
*
* Otherwise, the function returns a new Uint8Array instance with size `a.length - b.length`
*/ export function removeFromUint8Array(a, b) {
const tagIndex = indexOfUint8Array(a, b);
if (tagIndex === 0) return a.subarray(b.length);
if (tagIndex > -1) {
const removed = new Uint8Array(a.length - b.length);
removed.set(a.subarray(0, tagIndex));
removed.set(a.subarray(tagIndex + b.length), tagIndex);
return removed;
} else {
return a;
}
}
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