preserves/implementations/javascript/packages/schema/src/meta.ts

import { Value, preserves } from '@preserves/core';

export type Input = Value<never>;

export function isValidToken(s: string, allowLeadingUnderscore = false): boolean {
    if (allowLeadingUnderscore) {
        return /^[a-zA-Z_][a-zA-Z_0-9]*$/.test(s);
    } else {
        return /^[a-zA-Z][a-zA-Z_0-9]*$/.test(s);
    }
}

export const ANDSYM = Symbol.for('&');
export const DOT = Symbol.for('.');
export const DOTDOTDOT = Symbol.for('...');
export const EQUALS = Symbol.for('=');
export const ORSYM = Symbol.for('/');

export * from './schemaschema';
import { Schema, Pattern, $definitions } from './schemaschema';

export type Environment = Array<Schema>;

export function lookup(env: Environment, name: symbol): Pattern {
    for (const s of env) {
        const p = Schema._.details(s).get($definitions).get(name);
        if (p !== void 0) return p;
    }
    throw new Error(preserves`Schema: unbound name ${name}`);
}