64 lines
2.7 KiB
JavaScript
64 lines
2.7 KiB
JavaScript
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import { utf8DecodeJs } from "./utils/utf8.mjs";
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var DEFAULT_MAX_KEY_LENGTH = 16;
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var DEFAULT_MAX_LENGTH_PER_KEY = 16;
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var CachedKeyDecoder = /** @class */ (function () {
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function CachedKeyDecoder(maxKeyLength, maxLengthPerKey) {
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if (maxKeyLength === void 0) { maxKeyLength = DEFAULT_MAX_KEY_LENGTH; }
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if (maxLengthPerKey === void 0) { maxLengthPerKey = DEFAULT_MAX_LENGTH_PER_KEY; }
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this.maxKeyLength = maxKeyLength;
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this.maxLengthPerKey = maxLengthPerKey;
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this.hit = 0;
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this.miss = 0;
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// avoid `new Array(N)`, which makes a sparse array,
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// because a sparse array is typically slower than a non-sparse array.
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this.caches = [];
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for (var i = 0; i < this.maxKeyLength; i++) {
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this.caches.push([]);
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}
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}
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CachedKeyDecoder.prototype.canBeCached = function (byteLength) {
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return byteLength > 0 && byteLength <= this.maxKeyLength;
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};
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CachedKeyDecoder.prototype.find = function (bytes, inputOffset, byteLength) {
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var records = this.caches[byteLength - 1];
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FIND_CHUNK: for (var _i = 0, records_1 = records; _i < records_1.length; _i++) {
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var record = records_1[_i];
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var recordBytes = record.bytes;
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for (var j = 0; j < byteLength; j++) {
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if (recordBytes[j] !== bytes[inputOffset + j]) {
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continue FIND_CHUNK;
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}
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}
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return record.str;
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}
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return null;
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};
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CachedKeyDecoder.prototype.store = function (bytes, value) {
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var records = this.caches[bytes.length - 1];
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var record = { bytes: bytes, str: value };
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if (records.length >= this.maxLengthPerKey) {
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// `records` are full!
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// Set `record` to an arbitrary position.
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records[(Math.random() * records.length) | 0] = record;
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}
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else {
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records.push(record);
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}
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};
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CachedKeyDecoder.prototype.decode = function (bytes, inputOffset, byteLength) {
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var cachedValue = this.find(bytes, inputOffset, byteLength);
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if (cachedValue != null) {
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this.hit++;
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return cachedValue;
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}
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this.miss++;
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var str = utf8DecodeJs(bytes, inputOffset, byteLength);
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// Ensure to copy a slice of bytes because the byte may be NodeJS Buffer and Buffer#slice() returns a reference to its internal ArrayBuffer.
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var slicedCopyOfBytes = Uint8Array.prototype.slice.call(bytes, inputOffset, inputOffset + byteLength);
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this.store(slicedCopyOfBytes, str);
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return str;
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};
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return CachedKeyDecoder;
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}());
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export { CachedKeyDecoder };
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//# sourceMappingURL=CachedKeyDecoder.mjs.map
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