| 1 | import { enqueueRender } from './component';
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| 2 |
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| 3 | export let i = 0;
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| 4 |
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| 5 | export function createContext(defaultValue, contextId) {
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| 6 | contextId = '__cC' + i++;
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| 7 |
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| 8 | const context = {
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| 9 | _id: contextId,
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| 10 | _defaultValue: defaultValue,
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| 11 | Consumer(props, contextValue) {
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| 12 | // return props.children(
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| 13 | // context[contextId] ? context[contextId].props.value : defaultValue
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| 14 | // );
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| 15 | return props.children(contextValue);
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| 16 | },
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| 17 | Provider(props, subs, ctx) {
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| 18 | if (!this.getChildContext) {
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| 19 | subs = [];
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| 20 | ctx = {};
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| 21 | ctx[contextId] = this;
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| 22 |
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| 23 | this.getChildContext = () => ctx;
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| 24 |
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| 25 | this.shouldComponentUpdate = function(_props) {
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| 26 | if (this.props.value !== _props.value) {
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| 27 | // I think the forced value propagation here was only needed when `options.debounceRendering` was being bypassed:
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| 28 | // https://github.com/preactjs/preact/commit/4d339fb803bea09e9f198abf38ca1bf8ea4b7771#diff-54682ce380935a717e41b8bfc54737f6R358
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| 29 | // In those cases though, even with the value corrected, we're double-rendering all nodes.
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| 30 | // It might be better to just tell folks not to use force-sync mode.
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| 31 | // Currently, using `useContext()` in a class component will overwrite its `this.context` value.
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| 32 | // subs.some(c => {
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| 33 | // c.context = _props.value;
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| 34 | // enqueueRender(c);
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| 35 | // });
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| 36 |
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| 37 | // subs.some(c => {
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| 38 | // c.context[contextId] = _props.value;
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| 39 | // enqueueRender(c);
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| 40 | // });
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| 41 | subs.some(enqueueRender);
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| 42 | }
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| 43 | };
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| 44 |
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| 45 | this.sub = c => {
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| 46 | subs.push(c);
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| 47 | let old = c.componentWillUnmount;
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| 48 | c.componentWillUnmount = () => {
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| 49 | subs.splice(subs.indexOf(c), 1);
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| 50 | if (old) old.call(c);
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| 51 | };
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| 52 | };
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| 53 | }
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| 54 |
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| 55 | return props.children;
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| 56 | }
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| 57 | };
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| 58 |
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| 59 | // Devtools needs access to the context object when it
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| 60 | // encounters a Provider. This is necessary to support
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| 61 | // setting `displayName` on the context object instead
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| 62 | // of on the component itself. See:
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| 63 | // https://reactjs.org/docs/context.html#contextdisplayname
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| 64 |
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| 65 | return (context.Provider._contextRef = context.Consumer.contextType = context);
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| 66 | }
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