jssm
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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.
181 lines (180 loc) • 6.65 kB
JavaScript
import { JssmError } from './jssm_error';
/*******
*
* Predicate for validating an array for uniqueness. Not generally meant for
* external use.
*
*/
function arr_uniq_p(el, i, source) {
return source.indexOf(el) === i;
}
const array_box_if_string = n => typeof n === 'string' ? [n] : n;
// this is explicitly about other peoples' data, so it has to be weakly typed
/* eslint-disable flowtype/no-weak-types */
const weighted_rand_select = (options, probability_property = 'probability', rng) => {
if (!Array.isArray(options)) {
throw new TypeError('options must be a non-empty array of objects');
}
if (!(typeof options[0] === 'object')) {
throw new TypeError('options must be a non-empty array of objects');
}
const frand = (cap) => Math.random() * cap, or_one = (item) => item === undefined ? 1 : item, prob_sum = options.reduce((acc, val) => acc + or_one(val[probability_property]), 0), rnd = frand(prob_sum);
let cursor = 0, cursor_sum = 0;
while ((cursor_sum += or_one(options[cursor++][probability_property])) <= rnd) { } // eslint-disable-line no-empty,fp/no-loops
return options[cursor - 1];
};
/* eslint-enable flowtype/no-weak-types */
/*******
*
* Returns, for a non-negative integer argument `n`, the series `[0 .. n]`.
*
* ```typescript
* import { seq } from './jssm';
*
* seq(5); // [0, 1, 2, 3, 4]
* seq(0); // []
* ```
*
*/
function seq(n) {
if (!(Number.isInteger(n))) {
throw new TypeError('seq/1 takes a non-negative integer n as an argument');
}
if (n < 0) {
throw new TypeError('seq/1 takes a non-negative integer n as an argument');
}
return (new Array(n))
.fill(true)
.map((_, i) => i);
}
/*******
*
* Returns the histograph of an array as a `Map`. Makes no attempt to cope
* with deep equality; will fail for complex contents, as such.
*
* ```typescript
* import { histograph } from './jssm';
*
* histograph( [0, 0, 1, 1, 2, 2, 1] ); // Map()
* ```
*
*/
const histograph = (ar) => // eslint-disable-line flowtype/no-weak-types
ar.sort()
.reduce((m, v) => // TODO FIXME eslint-disable-line flowtype/no-weak-types,no-sequences
(m.set(v, (m.has(v) ? m.get(v) + 1 : 1)), m), new Map());
const weighted_sample_select = (n, options, probability_property) => // TODO FIXME no any // eslint-disable-line flowtype/no-weak-types
seq(n)
.map((_i) => // TODO FIXME eslint-disable-line flowtype/no-weak-types
weighted_rand_select(options, probability_property));
const weighted_histo_key = (n, opts, prob_prop, extract) => // TODO FIXME no any // eslint-disable-line flowtype/no-weak-types
histograph(weighted_sample_select(n, opts, prob_prop)
.map((s) => s[extract] // TODO FIXME eslint-disable-line flowtype/no-weak-types
));
/*******
*
* Internal method generating names for edges for the hook lookup map. Not
* meant for external use.
*
*/
function name_bind_prop_and_state(prop, state) {
if (typeof prop !== 'string') {
throw new JssmError(undefined, `Name of property must be a string; got ${prop}`);
}
if (typeof state !== 'string') {
throw new JssmError(undefined, `Name of state must be a string; got ${prop}`);
}
return JSON.stringify([prop, state]);
}
/*******
*
* Internal method generating names for edges for the hook lookup map. Not
* meant for external use.
*
*/
const hook_name = (from, to) => JSON.stringify([from, to]);
/*******
*
* Internal method generating names for actions for the hook lookup map. Not
* meant for external use.
*
*/
const named_hook_name = (from, to, action) => JSON.stringify([from, to, action]);
/*******
*
* Creates a SplitMix32 random generator. Used by the randomness test suite.
*
* Sourced from `bryc`: https://github.com/bryc/code/blob/master/jshash/PRNGs.md#splitmix32
*
* Replaces the Mulberry generator, which was found to have problems
*
*/
function gen_splitmix32(a) {
if (a === undefined) {
a = new Date().getTime();
}
return function () {
a |= 0;
a = a + 0x9e3779b9 | 0;
var t = a ^ a >>> 16;
t = Math.imul(t, 0x21f0aaad);
t = t ^ t >>> 15;
t = Math.imul(t, 0x735a2d97);
return ((t = t ^ t >>> 15) >>> 0) / 4294967296;
};
}
/*******
*
* Reduces an array to its unique contents. Compares with `===` and makes no
* effort to deep-compare contents; two matching arrays or objects contained
* will be treated as distinct, according to javascript rules. This also means
* that `NaNs` will be ***dropped***, because they do not self-compare.
*
* ```typescript
* unique( [] ); // []
* unique( [0,0] ); // [0]
* unique( [0,1,2, 0,1,2, 0,1,2] ); // [0,1,2]
* unique( [ [1], [1] ] ); // [ [1], [1] ] because arrays don't match
* unique( [0,NaN,2] ); // [0,2]
* ```
*
*/
const unique = (arr) => arr.filter((v, i, a) => a.indexOf(v) === i);
/*******
*
* Lists all repeated items in an array along with their counts. Subject to
* matching rules of Map. `NaN` is manually removed because of conflict rules
* around {@link unique}. Because these are compared with `===` and because
* arrays and objects never match that way unless they're the same object,
* arrays and objects are never considered repeats.
*
* ```typescript
* find_repeated<string>([ ]); // []
* find_repeated<string>([ "one" ]); // []
* find_repeated<string>([ "one", "two" ]); // []
* find_repeated<string>([ "one", "one" ]); // [ ["one", 2] ]
* find_repeated<string>([ "one", "two", "one" ]); // [ ["one", 2] ]
* find_repeated<number>([ 0, NaN, 0, NaN ]); // [ [0, 2] ]
* ```
*
*/
function find_repeated(arr) {
const uniqued = unique(arr);
if (uniqued.length !== arr.length) {
const residue_keys = new Map();
arr.forEach(k => residue_keys.set(k, residue_keys.has(k)
? (residue_keys.get(k) + 1)
: 1));
uniqued.forEach(k => residue_keys.set(k, residue_keys.get(k) - 1));
return [...residue_keys.entries()]
.filter((e) => ((e[1] > 0) && (!(Number.isNaN(e[0])))))
.map((e) => [e[0], e[1] + 1]);
}
else {
return [];
}
}
function sleep(ms) {
return new Promise(resolve => setTimeout(resolve, ms));
}
export { seq, unique, find_repeated, arr_uniq_p, histograph, weighted_histo_key, weighted_rand_select, weighted_sample_select, array_box_if_string, name_bind_prop_and_state, hook_name, named_hook_name, gen_splitmix32, sleep };