All files / src/internal/client/reactivity props.js

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import { DEV } from 'esm-env';
import {
	PROPS_IS_IMMUTABLE,
	PROPS_IS_LAZY_INITIAL,
	PROPS_IS_RUNES,
	PROPS_IS_UPDATED
} from '../../../constants.js';
import { get_descriptor, is_function } from '../utils.js';
import { mutable_source, set, source } from './sources.js';
import { derived, derived_safe_equal } from './deriveds.js';
import { get, is_signals_recorded, untrack, update } from '../runtime.js';
import { safe_equals } from './equality.js';
import * as e from '../errors.js';
import { LEGACY_DERIVED_PROP } from '../constants.js';
 
/**
 * @param {((value?: number) => number)} fn
 * @param {1 | -1} [d]
 * @returns {number}
 */
export function update_prop(fn, d = 1) {
	const value = fn();
	fn(value + d);
	return value;
}
 
/**
 * @param {((value?: number) => number)} fn
 * @param {1 | -1} [d]
 * @returns {number}
 */
export function update_pre_prop(fn, d = 1) {
	const value = fn() + d;
	fn(value);
	return value;
}
 
/**
 * The proxy handler for rest props (i.e. `const { x, ...rest } = $props()`).
 * Is passed the full `$$props` object and excludes the named props.
 * @type {ProxyHandler<{ props: Record<string | symbol, unknown>, exclude: Array<string | symbol>, name?: string }>}}
 */
const rest_props_handler = {
	get(target, key) {
		if (target.exclude.includes(key)) return;
		return target.props[key];
	},
	set(target, key) {
		if (DEV) {
			// TODO should this happen in prod too?
			e.props_rest_readonly(`${target.name}.${String(key)}`);
		}

		return false;
	},
	getOwnPropertyDescriptor(target, key) {
		if (target.exclude.includes(key)) return;
		if (key in target.props) {
			return {
				enumerable: true,
				configurable: true,
				value: target.props[key]
			};
		}
	},
	has(target, key) {
		if (target.exclude.includes(key)) return false;
		return key in target.props;
	},
	ownKeys(target) {
		return Reflect.ownKeys(target.props).filter((key) => !target.exclude.includes(key));
	}
};
 
/**
 * @param {Record<string, unknown>} props
 * @param {string[]} exclude
 * @param {string} [name]
 * @returns {Record<string, unknown>}
 */
export function rest_props(props, exclude, name) {
	return new Proxy(
		DEV ? { props, exclude, name, other: {}, to_proxy: [] } : { props, exclude },
		rest_props_handler
	);
}
 
/**
 * The proxy handler for legacy $$restProps and $$props
 * @type {ProxyHandler<{ props: Record<string | symbol, unknown>, exclude: Array<string | symbol>, special: Record<string | symbol, (v?: unknown) => unknown>, version: import('./types.js').Source<number> }>}}
 */
const legacy_rest_props_handler = {
	get(target, key) {
		if (target.exclude.includes(key)) return;
		get(target.version);
		return key in target.special ? target.special[key]() : target.props[key];
	},
	set(target, key, value) {
		if (!(key in target.special)) {
			// Handle props that can temporarily get out of sync with the parent
			/** @type {Record<string, (v?: unknown) => unknown>} */
			target.special[key] = prop(
				{
					get [key]() {
						return target.props[key];
					}
				},
				/** @type {string} */ (key),
				PROPS_IS_UPDATED
			);
		}
 
		target.special[key](value);
		update(target.version); // $$props is coarse-grained: when $$props.x is updated, usages of $$props.y etc are also rerun
		return true;
	},
	getOwnPropertyDescriptor(target, key) {
		if (target.exclude.includes(key)) return;
		if (key in target.props) {
			return {
				enumerable: true,
				configurable: true,
				value: target.props[key]
			};
		}
	},
	has(target, key) {
		if (target.exclude.includes(key)) return false;
		return key in target.props;
	},
	ownKeys(target) {
		return Reflect.ownKeys(target.props).filter((key) => !target.exclude.includes(key));
	}
};
 
/**
 * @param {Record<string, unknown>} props
 * @param {string[]} exclude
 * @returns {Record<string, unknown>}
 */
export function legacy_rest_props(props, exclude) {
	return new Proxy({ props, exclude, special: {}, version: source(0) }, legacy_rest_props_handler);
}
 
/**
 * The proxy handler for spread props. Handles the incoming array of props
 * that looks like `() => { dynamic: props }, { static: prop }, ..` and wraps
 * them so that the whole thing is passed to the component as the `$$props` argument.
 * @template {Record<string | symbol, unknown>} T
 * @type {ProxyHandler<{ props: Array<T | (() => T)> }>}}
 */
const spread_props_handler = {
	get(target, key) {
		let i = target.props.length;
		while (i--) {
			let p = target.props[i];
			if (is_function(p)) p = p();
			if (typeof p === 'object' && p !== null && key in p) return p[key];
		}
	},
	getOwnPropertyDescriptor(target, key) {
		let i = target.props.length;
		while (i--) {
			let p = target.props[i];
			if (is_function(p)) p = p();
			if (typeof p === 'object' && p !== null && key in p) return get_descriptor(p, key);
		}
	},
	has(target, key) {
		for (let p of target.props) {
			if (is_function(p)) p = p();
			if (p != null && key in p) return true;
		}
 
		return false;
	},
	ownKeys(target) {
		/** @type {Array<string | symbol>} */
		const keys = [];
 
		for (let p of target.props) {
			if (is_function(p)) p = p();
			for (const key in p) {
				if (!keys.includes(key)) keys.push(key);
			}
		}
 
		return keys;
	}
};
 
/**
 * @param {Array<Record<string, unknown> | (() => Record<string, unknown>)>} props
 * @returns {any}
 */
export function spread_props(...props) {
	return new Proxy({ props }, spread_props_handler);
}
 
/**
 * This function is responsible for synchronizing a possibly bound prop with the inner component state.
 * It is used whenever the compiler sees that the component writes to the prop, or when it has a default prop_value.
 * @template V
 * @param {Record<string, unknown>} props
 * @param {string} key
 * @param {number} flags
 * @param {V | (() => V)} [fallback]
 * @returns {(() => V | ((arg: V) => V) | ((arg: V, mutation: boolean) => V))}
 */
export function prop(props, key, flags, fallback) {
	var immutable = (flags & PROPS_IS_IMMUTABLE) !== 0;
	var runes = (flags & PROPS_IS_RUNES) !== 0;
	var lazy = (flags & PROPS_IS_LAZY_INITIAL) !== 0;
 
	var prop_value = /** @type {V} */ (props[key]);
	var setter = get_descriptor(props, key)?.set;
 
	var fallback_value = /** @type {V} */ (fallback);
	var fallback_dirty = true;
 
	var get_fallback = () => {
		if (lazy && fallback_dirty) {
			fallback_dirty = false;
			fallback_value = untrack(/** @type {() => V} */ (fallback));
		}
 
		return fallback_value;
	};
 
	if (prop_value === undefined && fallback !== undefined) {
		if (setter && runes) {
			e.props_invalid_value(key);
		}
 
		prop_value = get_fallback();
		if (setter) setter(prop_value);
	}
 
	/** @type {() => V} */
	var getter;
	if (runes) {
		getter = () => {
			var value = /** @type {V} */ (props[key]);
			if (value === undefined) return get_fallback();
			fallback_dirty = true;
			return value;
		};
	} else {
		// Svelte 4 did not trigger updates when a primitive value was updated to the same value.
		// Replicate that behavior through using a derived
		var derived_getter = (immutable ? derived : derived_safe_equal)(
			() => /** @type {V} */ (props[key])
		);
		derived_getter.f |= LEGACY_DERIVED_PROP;
		getter = () => {
			var value = get(derived_getter);
			if (value !== undefined) fallback_value = /** @type {V} */ (undefined);
			return value === undefined ? fallback_value : value;
		};
	}
 
	// easy mode — prop is never written to
	if ((flags & PROPS_IS_UPDATED) === 0) {
		return getter;
	}
 
	// intermediate mode — prop is written to, but the parent component had
	// `bind:foo` which means we can just call `$$props.foo = value` directly
	if (setter) {
		return function (/** @type {V} */ value) {
			if (arguments.length === 1) {
				/** @type {Function} */ (setter)(value);
				return value;
			} else {
				return getter();
			}
		};
	}
 
	// hard mode. this is where it gets ugly — the value in the child should
	// synchronize with the parent, but it should also be possible to temporarily
	// set the value to something else locally.
	var from_child = false;
	var was_from_child = false;
 
	// The derived returns the current value. The underlying mutable
	// source is written to from various places to persist this value.
	var inner_current_value = mutable_source(prop_value);
	var current_value = derived(() => {
		var parent_value = getter();
		var child_value = get(inner_current_value);
 
		if (from_child) {
			from_child = false;
			was_from_child = true;
			return child_value;
		}
 
		was_from_child = false;
		return (inner_current_value.v = parent_value);
	});
 
	if (!immutable) current_value.equals = safe_equals;
 
	return function (/** @type {V} */ value) {
		var current = get(current_value);
 
		// legacy nonsense — need to ensure the source is invalidated when necessary
		// also needed for when handling inspect logic so we can inspect the correct source signal
		if (is_signals_recorded) {
			// set this so that we don't reset to the parent value if `d`
			// is invalidated because of `invalidate_inner_signals` (rather
			// than because the parent or child value changed)
			from_child = was_from_child;
			// invoke getters so that signals are picked up by `invalidate_inner_signals`
			getter();
			get(inner_current_value);
		}
 
		if (arguments.length > 0) {
			if (!current_value.equals(value)) {
				from_child = true;
				set(inner_current_value, value);
				get(current_value); // force a synchronisation immediately
			}
 
			return value;
		}
 
		return current;
	};
}