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import { _IType, _ArgDefDetails, nil, DataType, IValue } from '../interfaces-private.ts';import { Types } from '../datatypes/index.ts';import { it } from '../utils.ts';import { QueryError } from '../interfaces.ts';
export interface HasSig {    name: string;    args: _ArgDefDetails[];    argsVariadic?: _IType | nil;}
export class OverloadResolver<T extends HasSig> {
    private byName = new Map<string, OverloadNode<T>>();
    constructor(private implicitCastOnly: boolean) { }
    add(value: T, replaceIfExists: boolean) {        let ret = this.byName.get(value.name);        if (!ret) {            this.byName.set(value.name, ret = new OverloadNode<T>(Types.null, this.implicitCastOnly, 0));        }        ret.index(value, replaceIfExists);    }
    getOverloads(name: string) {        const ovr = this.byName.get(name);        if (!ovr) {            return [];        }        return [...ovr.all()];    }
    remove(value: T) {        this.byName.get(value.name)?.unindex(value);    }
    resolve(name: string, args: IValue[]) {        return this.byName.get(name)?.resolve(args);    }
    getExact(name: string, types: _IType[]): T | nil {        return this.byName.get(name)?.getExact(types);    }}

class OverloadNode<T extends HasSig> {
    private nexts = new Map<DataType, OverloadNode<T>[]>();    private leaf: T | nil;
    constructor(readonly type: _IType, private implicitCastOnly: boolean, private at: number) {    }
    *all(): IterableIterator<T> {        if (this.leaf) {            yield this.leaf;        }        for (const children of this.nexts.values()) {            for (const child of children) {                yield* child.all();            }        }    }
    index(value: T, replaceIfExists: boolean) {        if (this.at >= value.args.length) {            if (this.leaf && !replaceIfExists) {                throw new QueryError('Function already exists: ' + value.name);            }            this.leaf = value;            return;        }        const arg = value.args[this.at];        const primary = arg.type.primary;        let lst = this.nexts.get(primary);        if (!lst) {            this.nexts.set(primary, lst = []);        }        // get or add corresponding node        let node = lst.find(x => x.type === arg.type);        if (!node) {            lst.push(node = new OverloadNode(arg.type, this.implicitCastOnly, this.at + 1));        }
        // process arg list        node.index(value, replaceIfExists);    }
    unindex(value: T) {        if (this.leaf === value) {            this.leaf = null;            return;        }        for (const children of this.nexts.values()) {            for (const child of children) {                child.unindex(value);            }        }    }
    getExact(types: _IType[]): T | nil {        if (this.at >= types.length) {            return this.leaf;        }        const target = types[this.at];        const found = this.nexts.get(target.primary)            ?.find(x => x.type == target);        return found?.getExact(types);    }
    resolve(args: IValue[]): T | nil {        if (this.at >= args.length) {            return this.leaf;        }
        // gets the child which type matches the current arg better        const arg = args[this.at];        const sigsToCheck = it(            this.nexts // perf tweak: search by primary type                .get(arg.type.primary)            ?? it(this.nexts.values()).flatten() // else, search all registered overloads        );
        const match = sigsToCheck.reduce<OverloadNode<T> | nil>((acc, x) => {            // check that arg can be converted to the target type            if (!this.compatible(arg, x.type)) {                return acc;            }            // first match            if (!acc) {                return x;            }            // returns the prefered type            return acc.type.prefer(x.type) === x.type ? x : acc;        }, null);
        if (match) {            return match.resolve(args);        }
        // handle variadic args        if (this.leaf && this.leaf.argsVariadic && this.compatible(arg, this.leaf.argsVariadic)) {            return this.leaf;        }
        // not found        return null;    }
    private compatible(givenArg: IValue, expectedArg: _IType) {        if (givenArg.type === expectedArg) {            return true;        }        return givenArg.isConstantLiteral            ? givenArg.type.canCast(expectedArg)            : givenArg.type.canConvertImplicit(expectedArg) ?? givenArg.type.canCast(expectedArg);    }}