calcium-lang/dist/expression/subscript.js

Calcium language interpreter

import { None } from "../factory";
import { default as Sym } from "../symbol";
import { evaluate, retrieveValue } from "../util";
/**
 * access the element by an index or a key
 */
export default class Subscript {
    /**
     *
     * @param referredObj
     * @param lower could be a single index or key. Otherwise the value from which
     * a slice starts.
     * @param upper the value at which a slice ends, if any
     */
    constructor(referredObj, lower, upper) {
        this.referredObj = referredObj;
        this.lower = lower;
        this.upper = upper;
    }
    assign(rhs, env) {
        const ref = evaluate(this.referredObj, env);
        if (this.upper === undefined) {
            const rhsValue = evaluate(rhs, env);
            const index = evaluate(this.lower, env);
            Reflect.get(ref, Sym.subscript)(index, rhsValue);
        }
        else {
            const rhsValue = retrieveValue(rhs, env); // Proxy cannot be used as a list
            const l = evaluate(this.lower, env);
            const u = evaluate(this.upper, env);
            Reflect.get(ref, Sym.slice)(l, u, rhsValue);
        }
    }
    [Sym.evaluate](env) {
        const ref = evaluate(this.referredObj, env);
        if (this.upper === undefined) {
            const index = evaluate(this.lower, env);
            return Reflect.get(ref, Sym.subscript)(index);
        }
        else {
            const l = evaluate(this.lower, env);
            const u = evaluate(this.upper, env);
            return Reflect.get(ref, Sym.slice)(l, u);
        }
    }
    get [Sym.description]() {
        if (this.upper === undefined) {
            return `${Reflect.get(this.referredObj, Sym.description)}[${Reflect.get(this.lower, Sym.description)}]`;
        }
        else {
            // consider the cases such as `a[:-1]` or `a[:]`.
            const lowerStr = this.lower === None ? "" : Reflect.get(this.lower, Sym.description);
            const upperStr = this.upper === None ? "" : Reflect.get(this.upper, Sym.description);
            return `${Reflect.get(this.referredObj, Sym.description)}[${lowerStr}:${upperStr}]`;
        }
    }
}
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