preserves/implementations/javascript/packages/core/src/annotated.ts

import { Encoder } from "./encoder";
import { Tag } from "./constants";
import { AsPreserve, PreserveOn } from "./symbols";
import { DefaultPointer, Value } from "./values";
import { is, isAnnotated, IsPreservesAnnotated } from "./is";
import { stringify } from "./text";

export class Annotated<T = DefaultPointer> {
    readonly annotations: Array<Value<T>>;
    readonly item: Value<T>;

    constructor(item: Value<T>) {
        this.annotations = [];
        this.item = item;
    }

    [AsPreserve](): Value<T> {
        return this;
    }

    [PreserveOn](encoder: Encoder<T>) {
        if (encoder.includeAnnotations) {
            for (const a of this.annotations) {
                encoder.emitbyte(Tag.Annotation);
                encoder.push(a);
            }
        }
        encoder.push(this.item);
    }

    equals(other: any): boolean {
        return is(this.item, Annotated.isAnnotated(other) ? other.item : other);
    }

    // hashCode(): number {
    //     return hash(this.item);
    // }

    toString(): string {
        return this.asPreservesText();
    }

    asPreservesText(): string {
        const anns = this.annotations.map((a) => '@' + stringify(a)).join(' ');
        return (anns ? anns + ' ' : anns) + stringify(this.item);
    }

    get [IsPreservesAnnotated](): boolean {
        return true;
    }

    static isAnnotated<T = DefaultPointer>(x: any): x is Annotated<T> {
        return isAnnotated(x);
    }
}

export function annotate<T = DefaultPointer>(v0: Value<T>, ...anns: Value<T>[]): Annotated<T> {
    const v = Annotated.isAnnotated<T>(v0) ? v0 : new Annotated(v0);
    anns.forEach((a) => v.annotations.push(a));
    return v;
}