functionalscript/types/btree/find/module.f.js

FunctionalScript is a purely functional subset of JavaScript

import { index3, index5 } from "../../function/compare/module.f.js";
const child = (item) => item[1][item[0]];
export const find = (c) => {
    const i3 = index3(c);
    const i5 = index5(c);
    const f = (tail) => (node) => {
        const append = index => {
            const first = [index, node];
            return f({ first, tail })(child(first));
        };
        const done = index => ({ first: [index, node], tail });
        switch (node.length) {
            case 1: {
                return done(i3(node[0]));
            }
            case 2: {
                return done(i5(node));
            }
            case 3: {
                const i = i3(node[1]);
                switch (i) {
                    case 0:
                    case 2: {
                        return append(i);
                    }
                    case 1: {
                        return done(i);
                    }
                }
            }
            case 5: {
                const i = i5([node[1], node[3]]);
                switch (i) {
                    case 0:
                    case 2:
                    case 4: {
                        return append(i);
                    }
                    case 1:
                    case 3: {
                        return done(i);
                    }
                }
            }
        }
    };
    return f(null);
};
export const isFound = ([i]) => {
    switch (i) {
        case 1:
        case 3: {
            return true;
        }
        default: {
            return false;
        }
    }
};
export const value = ([i, r]) => {
    switch (i) {
        case 1: {
            switch (r.length) {
                case 1:
                case 2: {
                    return r[0];
                }
                default: {
                    return r[1];
                }
            }
        }
        case 3: {
            return r.length === 2 ? r[1] : r[3];
        }
        default: {
            return null;
        }
    }
};