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Frptools uses a hash function now instead of a comparator

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This commit is contained in:
Timothy Farrell 2017-11-20 20:57:18 -06:00
parent 914779fb44
commit 1e29d2d7a4
7 changed files with 58 additions and 54 deletions
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50
README.md
View File

@ -51,22 +51,24 @@ const remainingSubscriptionCount = unsubscribe();
inViewport.unsubscribeAll(); // Call unsubscribeAll to remove child property/computed subscriptions.
```
### Provide a comparator for complex types
### Provide a hash function for complex types
When storing a type that is not determined to be equal with simple equality (===), provide a
function to determine in the new provided value should be propagated to dependents.
When storing a type that is not determined to be equal with simple equality (===), provide a hash
function to be used for simple comparison to determine if the new provided value should be
propagated to dependents.
```js
function setEquals(a, b) {
return (
a instanceof Set &&
b instanceof Set &&
[...a].reduce((acc, d) => acc && b.has(d), true) &&
[...b].reduce((acc, d) => acc && a.has(d), true)
);
function hashSet(_a) {
if (_a instanceof Set) {
return Array.from(_a.keys())
.sort()
.map(k => `${(typeof k).substr(0, 1)}:${encodeURIComponent(k)}/`)
.join('?');
}
return _a;
}
const a = prop(new Set([1, 2]), setEquals);
const a = prop(new Set([1, 2]), hashSet);
```
# [computed](./src/computed.js)
@ -137,28 +139,30 @@ showDialog.detach(); // Call detach to remove this computed from the logic tree.
showDialog.unsubscribeAll(); // Call unsubscribeAll to remove child property/computed subscriptions.
```
### Provide a comparator for complex types
### Provide a hash function for complex types
When the computed result is a type that is not determined to be equal with simple equality (===),
provide a function to determine in the new provided value should be propagated to dependents.
provide a hash function to be used for simple comparison to determine if the new provided value
should be propagated to dependents.
```js
function setEquals(a, b) {
return (
a instanceof Set &&
b instanceof Set &&
[...a].reduce((acc, d) => acc && b.has(d), true) &&
[...b].reduce((acc, d) => acc && a.has(d), true)
);
function hashSet(_a) {
if (_a instanceof Set) {
return Array.from(_a.keys())
.sort()
.map(k => `${(typeof k).substr(0, 1)}:${encodeURIComponent(k)}/`)
.join('?');
}
return _a;
}
function _intersection(a, b) {
return new Set([...a].filter(x => b.has(x)));
}
const a = prop(new Set([1, 2]), setEquals);
const b = prop(new Set([2, 3]), setEquals);
const intersection = computed(_intersection, [a, b], setEquals);
const a = prop(new Set([1, 2]), hashSet);
const b = prop(new Set([2, 3]), hashSet);
const intersection = computed(_intersection, [a, b], hashSet);
```
# [bundle](./src/bundle.js)

2
package.json
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@ -1,6 +1,6 @@
{
"name": "frptools",
"version": "2.0.0",
"version": "2.1.0",
"description": "Observable Property and Computed data streams",
"main": "lib/index.js",
"jsnext:main": "src/index.js",

16
spec/computed.spec.js
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@ -1,4 +1,5 @@
const { prop, computed } = require('../lib/index.js');
const { hashSet } = require('../lib/util.js');
describe('computed', () => {
const add = (a, b) => a + b;
@ -157,15 +158,6 @@ describe('computed', () => {
});
it('uses a comparator', () => {
function setEquals(a, b) {
return (
a instanceof Set &&
b instanceof Set &&
[...a].reduce((acc, d) => acc && b.has(d), true) &&
[...b].reduce((acc, d) => acc && a.has(d), true)
);
}
let runCount = 0;
function intersection(a, b) {
@ -173,9 +165,9 @@ describe('computed', () => {
return new Set([...a].filter(x => b.has(x)));
}
const a = prop(new Set([1, 2]), setEquals);
const b = prop(new Set([2, 3]), setEquals);
const ABintersection = computed(intersection, [a, b], setEquals);
const a = prop(new Set([1, 2]), hashSet);
const b = prop(new Set([2, 3]), hashSet);
const ABintersection = computed(intersection, [a, b], hashSet);
expect(runCount).toEqual(0);
expect([...ABintersection()]).toEqual([2]);

14
spec/property.spec.js
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@ -1,4 +1,5 @@
const { prop } = require('../lib/index.js');
const { hashSet } = require('../lib/util.js');
describe('A property', () => {
it('returns its initialized value', () => {
@ -62,19 +63,10 @@ describe('A property', () => {
expect(runCount).toEqual(3);
});
it('uses a comparator', () => {
function setEquals(a, b) {
return (
a instanceof Set &&
b instanceof Set &&
[...a].reduce((acc, d) => acc && b.has(d), true) &&
[...b].reduce((acc, d) => acc && a.has(d), true)
);
}
it('uses a hash function', () => {
let runCount = 0;
const a = prop(new Set([1, 2]), setEquals);
const a = prop(new Set([1, 2]), hashSet);
a.subscribe(() => (runCount += 1));
expect([...a()]).toEqual([1, 2]);
expect(runCount).toEqual(0);

9
src/computed.js
View File

@ -1,10 +1,11 @@
import { eq } from './util.js';
import { id } from './util.js';
export function computed(fn, dependencies = [], comparator = eq) {
export function computed(fn, dependencies = [], hash = id) {
const subscribers = new Set();
const dependents = new Set();
let isDirty = true;
let val;
let id;
// Receive dirty flag from parent logic node (dependency). Pass it down.
function _computedDirtyReporter(_, skipPropagation) {
@ -25,7 +26,9 @@ export function computed(fn, dependencies = [], comparator = eq) {
if (isDirty) {
const newVal = fn.apply(null, dependencies.map(runParam));
isDirty = false;
if (!comparator(val, newVal)) {
const newId = hash(newVal);
if (id !== newId) {
id = newId;
val = newVal;
subscribers.forEach(s => s(val));
}

9
src/property.js
View File

@ -1,10 +1,13 @@
import { eq } from './util.js';
import { id } from './util.js';
export function prop(store, comparator = eq) {
export function prop(store, hash = id) {
const subscribers = new Set();
let id = hash(store);
const accessor = function _prop(newVal) {
if (newVal !== undefined && !comparator(store, newVal)) {
const newId = hash(newVal);
if (newVal !== undefined && id !== newId) {
id = newId;
store = newVal;
subscribers.forEach(s => s(store));
}

12
src/util.js
View File

@ -1 +1,11 @@
export const eq = (a, b) => a === b;
export const id = a => a;
export function hashSet(_a) {
if (_a instanceof Set) {
return Array.from(_a.keys())
.sort()
.map(k => `${(typeof k).substr(0, 1)}:${encodeURIComponent(k)}/`)
.join('?');
}
return _a;
}