thi-ng/umbrella

import type { Fn, Predicate } from "@thi.ng/api";
import type { Parser } from "../api.js";

export const string =
    <T>(str: ArrayLike<T>, id = "string"): Parser<T> =>
    (ctx) => {
        if (ctx.done) return false;
        const scope = ctx.start(id);
        const state = scope.state!;
        const reader = ctx.reader;
        for (let i = 0, n = str.length; i < n; i++) {
            if (state.done) return false;
            const r = reader.read(state);
            if (r !== str[i]) {
                return ctx.discard();
            }
            reader.next(state);
        }
        scope.result = str;
        return ctx.end();
    };

export const stringD =
    <T>(str: ArrayLike<T>): Parser<T> =>
    (ctx) => {
        if (ctx.done) return false;
        const state = ctx.state.copy();
        const reader = ctx.reader;
        for (let i = 0, n = str.length; i < n; i++) {
            if (state.done) return false;
            const r = reader.read(state);
            if (r !== str[i]) {
                return false;
            }
            reader.next(state);
        }
        ctx.state = state;
        return true;
    };

export const stringOf =
    <T>(
        pred: Predicate<T>,
        id = "string",
        reduce: Fn<T[], any> = (x) => x.join("")
    ): Parser<T> =>
    (ctx) => {
        const state = ctx.state.copy();
        const reader = ctx.reader;
        let acc: T[] = [];
        while (!state.done) {
            const r = reader.read(state);
            if (!pred(r)) break;
            acc.push(r);
            reader.next(state);
        }
        return ctx.addChild(id, reduce(acc), state);
    };