jssm/dist/es6/jssm_arrow.js

A Javascript finite state machine (FSM) with a terse DSL and a simple API. Most FSMs are one-liners. Fast, easy, powerful, well tested, typed with TypeScript, and visualizations. MIT License.

import { JssmError } from './jssm_error';
/* eslint-disable complexity */
/*********
 *
 *  Return the direction of an arrow - `right`, `left`, or `both`.
 *
 *  ```typescript
 *  import { arrow_direction } from 'jssm';
 *
 *  arrow_direction('->');    // 'right'
 *  arrow_direction('<~=>');  // 'both'
 *  ```
 *
 *  @param arrow The arrow to be evaluated
 *
 */
function arrow_direction(arrow) {
    switch (String(arrow)) {
        case '->':
        case '→':
        case '=>':
        case '⇒':
        case '~>':
        case '↛':
            return 'right';
        case '<-':
        case '←':
        case '<=':
        case '⇐':
        case '<~':
        case '↚':
            return 'left';
        case '<->':
        case '↔':
        case '<-=>':
        case '←⇒':
        case '←=>':
        case '<-⇒':
        case '<-~>':
        case '←↛':
        case '←~>':
        case '<-↛':
        case '<=>':
        case '⇔':
        case '<=->':
        case '⇐→':
        case '⇐->':
        case '<=→':
        case '<=~>':
        case '⇐↛':
        case '⇐~>':
        case '<=↛':
        case '<~>':
        case '↮':
        case '<~->':
        case '↚→':
        case '↚->':
        case '<~→':
        case '<~=>':
        case '↚⇒':
        case '↚=>':
        case '<~⇒':
            return 'both';
        default:
            throw new JssmError(undefined, `arrow_direction: unknown arrow type ${arrow}`);
    }
}
/* eslint-enable complexity */
/* eslint-disable complexity */
/*********
 *
 *  Return the direction of an arrow - `right`, `left`, or `both`.
 *
 *  ```typescript
 *  import { arrow_left_kind } from 'jssm';
 *
 *  arrow_left_kind('<-');    // 'legal'
 *  arrow_left_kind('<=');    // 'main'
 *  arrow_left_kind('<~');    // 'forced'
 *  arrow_left_kind('<->');   // 'legal'
 *  arrow_left_kind('->');    // 'none'
 *  ```
 *
 *  @param arrow The arrow to be evaluated
 *
 */
function arrow_left_kind(arrow) {
    switch (String(arrow)) {
        case '->':
        case '→':
        case '=>':
        case '⇒':
        case '~>':
        case '↛':
            return 'none';
        case '<-':
        case '←':
        case '<->':
        case '↔':
        case '<-=>':
        case '←⇒':
        case '<-~>':
        case '←↛':
            return 'legal';
        case '<=':
        case '⇐':
        case '<=>':
        case '⇔':
        case '<=->':
        case '⇐→':
        case '<=~>':
        case '⇐↛':
            return 'main';
        case '<~':
        case '↚':
        case '<~>':
        case '↮':
        case '<~->':
        case '↚→':
        case '<~=>':
        case '↚⇒':
            return 'forced';
        default:
            throw new JssmError(undefined, `arrow_direction: unknown arrow type ${arrow}`);
    }
}
/* eslint-enable complexity */
/* eslint-disable complexity */
/*********
 *
 *  Return the direction of an arrow - `right`, `left`, or `both`.
 *
 *  ```typescript
 *  import { arrow_left_kind } from 'jssm';
 *
 *  arrow_left_kind('->');    // 'legal'
 *  arrow_left_kind('=>');    // 'main'
 *  arrow_left_kind('~>');    // 'forced'
 *  arrow_left_kind('<->');   // 'legal'
 *  arrow_left_kind('<-');    // 'none'
 *  ```
 *
 *  @param arrow The arrow to be evaluated
 *
 */
function arrow_right_kind(arrow) {
    switch (String(arrow)) {
        case '<-':
        case '←':
        case '<=':
        case '⇐':
        case '<~':
        case '↚':
            return 'none';
        case '->':
        case '→':
        case '<->':
        case '↔':
        case '<=->':
        case '⇐→':
        case '<~->':
        case '↚→':
            return 'legal';
        case '=>':
        case '⇒':
        case '<=>':
        case '⇔':
        case '<-=>':
        case '←⇒':
        case '<~=>':
        case '↚⇒':
            return 'main';
        case '~>':
        case '↛':
        case '<~>':
        case '↮':
        case '<-~>':
        case '←↛':
        case '<=~>':
        case '⇐↛':
            return 'forced';
        default:
            throw new JssmError(undefined, `arrow_direction: unknown arrow type ${arrow}`);
    }
}
/* eslint-enable complexity */
export { arrow_direction, arrow_left_kind, arrow_right_kind };