300 lines
9.1 KiB
TypeScript
300 lines
9.1 KiB
TypeScript
import { Tag } from "./constants";
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import { Bytes } from "./bytes";
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import { Value } from "./values";
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import { PreserveOn } from "./symbols";
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import { EncodeError } from "./codec";
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import { Record, Tuple } from "./record";
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import { GenericEmbedded, EmbeddedTypeEncode } from "./embedded";
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export type Encodable<T> =
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Value<T> | Preservable<T> | Iterable<Value<T>> | ArrayBufferView;
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export interface Preservable<T> {
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[PreserveOn](encoder: Encoder<T>): void;
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}
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export function isPreservable<T>(v: any): v is Preservable<T> {
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return typeof v === 'object' && v !== null && typeof v[PreserveOn] === 'function';
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}
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export interface EncoderOptions {
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canonical?: boolean;
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includeAnnotations?: boolean;
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}
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export interface EncoderEmbeddedOptions<T> extends EncoderOptions {
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embeddedEncode?: EmbeddedTypeEncode<T>;
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}
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export function asLatin1(bs: Uint8Array): string {
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return String.fromCharCode.apply(null, bs as any as number[]);
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}
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function isIterable<T>(v: any): v is Iterable<T> {
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return typeof v === 'object' && v !== null && typeof v[Symbol.iterator] === 'function';
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}
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let _nextId = 0;
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const _registry = new WeakMap<object, number>();
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export function embeddedId(v: any): number {
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let id = _registry.get(v);
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if (id === void 0) {
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id = _nextId++;
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_registry.set(v, id);
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}
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return id;
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}
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export const identityEmbeddedTypeEncode: EmbeddedTypeEncode<any> = {
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encode(s: EncoderState, v: any): void {
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new Encoder(s, this).push(embeddedId(v));
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},
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toValue(v: any): Value<GenericEmbedded> {
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return embeddedId(v);
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}
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};
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export class EncoderState {
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chunks: Array<Uint8Array>;
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view: DataView;
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index: number;
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options: EncoderOptions;
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constructor(options: EncoderOptions) {
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this.chunks = [];
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this.view = new DataView(new ArrayBuffer(256));
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this.index = 0;
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this.options = options;
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}
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get canonical(): boolean {
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return this.options.canonical ?? true;
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}
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get includeAnnotations(): boolean {
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return this.options.includeAnnotations ?? !this.canonical;
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}
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contents(): Bytes {
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if (this.chunks.length === 0) {
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const resultLength = this.index;
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this.index = 0;
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return new Bytes(this.view.buffer.slice(0, resultLength));
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} else {
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this.rotatebuffer(4096);
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return Bytes.concat(this.chunks);
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}
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}
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/* Like contents(), but hands back a string containing binary data "encoded" via latin-1 */
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contentsString(): string {
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if (this.chunks.length === 0) {
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const s = asLatin1(new Uint8Array(this.view.buffer, 0, this.index));
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this.index = 0;
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return s;
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} else {
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this.rotatebuffer(4096);
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return this.chunks.map(asLatin1).join('');
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}
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}
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rotatebuffer(size: number) {
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this.chunks.push(new Uint8Array(this.view.buffer, 0, this.index));
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this.view = new DataView(new ArrayBuffer(size));
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this.index = 0;
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}
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makeroom(amount: number) {
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if (this.index + amount > this.view.byteLength) {
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this.rotatebuffer(amount + 4096);
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}
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}
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emitbyte(b: number) {
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this.makeroom(1);
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this.view.setUint8(this.index++, b);
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}
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emitbytes(bs: Uint8Array) {
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this.makeroom(bs.length);
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(new Uint8Array(this.view.buffer)).set(bs, this.index);
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this.index += bs.length;
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}
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varint(v: number) {
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while (v >= 128) {
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this.emitbyte((v % 128) + 128);
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v = Math.floor(v / 128);
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}
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this.emitbyte(v);
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}
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encodeint(v: number) {
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// TODO: Bignums :-/
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const plain_bitcount = Math.floor(Math.log2(v > 0 ? v : -(1 + v))) + 1;
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const signed_bitcount = plain_bitcount + 1;
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const bytecount = (signed_bitcount + 7) >> 3;
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if (bytecount <= 16) {
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this.emitbyte(Tag.MediumInteger_lo + bytecount - 1);
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} else {
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this.emitbyte(Tag.SignedInteger);
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this.varint(bytecount);
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}
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const enc = (n: number, x: number) => {
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if (n > 0) {
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enc(n - 1, Math.floor(x / 256));
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this.emitbyte(x & 255);
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}
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};
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enc(bytecount, v);
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}
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encodebytes(tag: Tag, bs: Uint8Array) {
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this.emitbyte(tag);
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this.varint(bs.length);
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this.emitbytes(bs);
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}
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}
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export class Encoder<T = object> {
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state: EncoderState;
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embeddedEncode: EmbeddedTypeEncode<T>;
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constructor(options: EncoderEmbeddedOptions<T>);
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constructor(state: EncoderState, embeddedEncode?: EmbeddedTypeEncode<T>);
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constructor(
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state_or_options: (EncoderState | EncoderEmbeddedOptions<T>) = {},
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embeddedEncode?: EmbeddedTypeEncode<T>)
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{
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if (state_or_options instanceof EncoderState) {
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this.state = state_or_options;
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this.embeddedEncode = embeddedEncode ?? identityEmbeddedTypeEncode;
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} else {
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this.state = new EncoderState(state_or_options);
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this.embeddedEncode = state_or_options.embeddedEncode ?? identityEmbeddedTypeEncode;
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}
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}
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withEmbeddedEncode<S>(
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embeddedEncode: EmbeddedTypeEncode<S>,
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body: (e: Encoder<S>) => void): this
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{
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body(new Encoder(this.state, embeddedEncode));
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return this;
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}
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get canonical(): boolean {
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return this.state.canonical;
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}
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get includeAnnotations(): boolean {
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return this.state.includeAnnotations;
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}
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contents(): Bytes {
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return this.state.contents();
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}
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contentsString(): string {
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return this.state.contentsString();
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}
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encodevalues(tag: Tag, items: Iterable<Value<T>>) {
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this.state.emitbyte(tag);
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for (let i of items) { this.push(i); }
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this.state.emitbyte(Tag.End);
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}
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push(v: Encodable<T>) {
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if (isPreservable<never>(v)) {
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v[PreserveOn](this as unknown as Encoder<never>);
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}
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else if (isPreservable<T>(v)) {
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v[PreserveOn](this);
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}
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else if (typeof v === 'boolean') {
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this.state.emitbyte(v ? Tag.True : Tag.False);
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}
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else if (typeof v === 'number') {
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if (v >= -3 && v <= 12) {
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this.state.emitbyte(Tag.SmallInteger_lo + ((v + 16) & 0xf));
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} else {
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this.state.encodeint(v);
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}
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}
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else if (typeof v === 'string') {
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this.state.encodebytes(Tag.String, new Bytes(v)._view);
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}
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else if (typeof v === 'symbol') {
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const key = Symbol.keyFor(v);
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if (key === void 0) throw new EncodeError("Cannot preserve non-global Symbol", v);
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this.state.encodebytes(Tag.Symbol, new Bytes(key)._view);
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}
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else if (ArrayBuffer.isView(v)) {
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if (v instanceof Uint8Array) {
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this.state.encodebytes(Tag.ByteString, v);
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} else {
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const bs = new Uint8Array(v.buffer, v.byteOffset, v.byteLength);
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this.state.encodebytes(Tag.ByteString, bs);
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}
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}
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else if (Record.isRecord<Value<T>, Tuple<Value<T>>, T>(v)) {
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this.state.emitbyte(Tag.Record);
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this.push(v.label);
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for (let i of v) { this.push(i); }
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this.state.emitbyte(Tag.End);
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}
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else if (Array.isArray(v)) {
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this.encodevalues(Tag.Sequence, v);
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}
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else if (isIterable<Value<T>>(v)) {
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this.encodevalues(Tag.Sequence, v as Iterable<Value<T>>);
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}
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else {
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this.state.emitbyte(Tag.Embedded);
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this.embeddedEncode.encode(this.state, v.embeddedValue);
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}
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return this; // for chaining
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}
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}
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export function encode<T>(
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v: Encodable<T>,
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options: EncoderEmbeddedOptions<T> = {}): Bytes
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{
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return new Encoder(options).push(v).contents();
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}
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const _canonicalEncoder = new Encoder({ canonical: true });
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let _usingCanonicalEncoder = false;
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export function canonicalEncode(v: Encodable<never>, options?: EncoderEmbeddedOptions<never>): Bytes;
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export function canonicalEncode(v: Encodable<any>, options?: EncoderEmbeddedOptions<any>): Bytes;
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export function canonicalEncode(v: any, options?: EncoderEmbeddedOptions<any>): Bytes {
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if (options === void 0 && !_usingCanonicalEncoder) {
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_usingCanonicalEncoder = true;
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const bs = _canonicalEncoder.push(v).contents();
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_usingCanonicalEncoder = false;
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return bs;
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} else {
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return encode(v, { ... options, canonical: true });
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}
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}
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export function canonicalString(v: Encodable<any>): string {
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if (!_usingCanonicalEncoder) {
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_usingCanonicalEncoder = true;
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const s = _canonicalEncoder.push(v).contentsString();
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_usingCanonicalEncoder = false;
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return s;
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} else {
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return new Encoder({ canonical: true }).push(v).contentsString();
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}
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}
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export function encodeWithAnnotations<T>(v: Encodable<T>,
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options: EncoderEmbeddedOptions<T> = {}): Bytes {
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return encode(v, { ... options, includeAnnotations: true });
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}
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