mirror of
https://github.com/denoland/deno.git
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793089bdf0
This commit renames "deno_core::InternalModuleLoader" to "ExtModuleLoader" and changes the specifiers used by the modules loaded from this loader to "ext:". "internal:" scheme was really ambiguous and it's more characters than "ext:", which should result in slightly smaller snapshot size. Closes https://github.com/denoland/deno/issues/18020
160 lines
4 KiB
TypeScript
160 lines
4 KiB
TypeScript
// Copyright 2018-2023 the Deno authors. All rights reserved. MIT license.
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import { Encodings } from "ext:deno_node/internal_binding/_node.ts";
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export function indexOfNeedle(
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source: Uint8Array,
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needle: Uint8Array,
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start = 0,
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): number {
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if (start >= source.length) {
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return -1;
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}
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if (start < 0) {
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start = Math.max(0, source.length + start);
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}
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const s = needle[0];
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for (let i = start; i < source.length; i++) {
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if (source[i] !== s) continue;
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const pin = i;
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let matched = 1;
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let j = i;
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while (matched < needle.length) {
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j++;
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if (source[j] !== needle[j - pin]) {
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break;
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}
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matched++;
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}
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if (matched === needle.length) {
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return pin;
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}
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}
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return -1;
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}
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export function numberToBytes(n: number): Uint8Array {
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if (n === 0) return new Uint8Array([0]);
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const bytes = [];
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bytes.unshift(n & 255);
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while (n >= 256) {
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n = n >>> 8;
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bytes.unshift(n & 255);
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}
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return new Uint8Array(bytes);
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}
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// TODO(Soremwar)
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// Check if offset or buffer can be transform in order to just use std's lastIndexOf directly
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// This implementation differs from std's lastIndexOf in the fact that
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// it also includes items outside of the offset as long as part of the
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// set is contained inside of the offset
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// Probably way slower too
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function findLastIndex(
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targetBuffer: Uint8Array,
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buffer: Uint8Array,
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offset: number,
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) {
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offset = offset > targetBuffer.length ? targetBuffer.length : offset;
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const searchableBuffer = targetBuffer.slice(0, offset + buffer.length);
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const searchableBufferLastIndex = searchableBuffer.length - 1;
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const bufferLastIndex = buffer.length - 1;
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// Important to keep track of the last match index in order to backtrack after an incomplete match
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// Not doing this will cause the search to skip all possible matches that happened in the
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// last match range
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let lastMatchIndex = -1;
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let matches = 0;
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let index = -1;
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for (let x = 0; x <= searchableBufferLastIndex; x++) {
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if (
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searchableBuffer[searchableBufferLastIndex - x] ===
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buffer[bufferLastIndex - matches]
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) {
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if (lastMatchIndex === -1) {
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lastMatchIndex = x;
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}
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matches++;
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} else {
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matches = 0;
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if (lastMatchIndex !== -1) {
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// Restart the search right after the last index was ignored
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x = lastMatchIndex + 1;
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lastMatchIndex = -1;
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}
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continue;
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}
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if (matches === buffer.length) {
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index = x;
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break;
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}
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}
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if (index === -1) return index;
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return searchableBufferLastIndex - index;
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}
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// TODO(@bartlomieju):
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// Take encoding into account when evaluating index
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function indexOfBuffer(
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targetBuffer: Uint8Array,
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buffer: Uint8Array,
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byteOffset: number,
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encoding: Encodings,
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forwardDirection: boolean,
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) {
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if (!Encodings[encoding] === undefined) {
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throw new Error(`Unknown encoding code ${encoding}`);
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}
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if (!forwardDirection) {
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// If negative the offset is calculated from the end of the buffer
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if (byteOffset < 0) {
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byteOffset = targetBuffer.length + byteOffset;
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}
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if (buffer.length === 0) {
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return byteOffset <= targetBuffer.length
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? byteOffset
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: targetBuffer.length;
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}
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return findLastIndex(targetBuffer, buffer, byteOffset);
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}
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if (buffer.length === 0) {
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return byteOffset <= targetBuffer.length ? byteOffset : targetBuffer.length;
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}
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return indexOfNeedle(targetBuffer, buffer, byteOffset);
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}
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// TODO(Soremwar)
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// Node's implementation is a very obscure algorithm that I haven't been able to crack just yet
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function indexOfNumber(
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targetBuffer: Uint8Array,
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number: number,
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byteOffset: number,
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forwardDirection: boolean,
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) {
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const bytes = numberToBytes(number);
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if (bytes.length > 1) {
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throw new Error("Multi byte number search is not supported");
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}
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return indexOfBuffer(
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targetBuffer,
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numberToBytes(number),
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byteOffset,
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Encodings.UTF8,
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forwardDirection,
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);
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}
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export default { indexOfBuffer, indexOfNumber };
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export { indexOfBuffer, indexOfNumber };
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