@mapwhit/style-expressions/lib/expression/definitions/global_state.js

Process expressions in map style.

import getOwn from '../../util/get_own.js';
import { ValueType } from '../types.js';

export default class GlobalState {
  constructor(key) {
    this.type = ValueType;
    this.key = key;
  }

  static parse(args, context) {
    if (args.length !== 2) {
      return context.error(`Expected 1 argument, but found ${args.length - 1} instead.`);
    }

    const key = args[1];

    if (key === undefined || key === null) {
      return context.error('Global state property must be defined.');
    }

    if (typeof key !== 'string') {
      return context.error(`Global state property must be string, but found ${typeof args[1]} instead.`);
    }

    return new GlobalState(key);
  }

  evaluate(ctx) {
    const globalState = ctx.globals?.globalState;

    if (!globalState || Object.keys(globalState).length === 0) return null;

    return getOwn(globalState, this.key);
  }

  eachChild() {}

  outputDefined() {
    return false;
  }
}