@tldraw/state
Version:
tldraw infinite canvas SDK (state).
233 lines (232 loc) • 7.49 kB
JavaScript
import { assert } from "@tldraw/utils";
import { ArraySet } from "./ArraySet.mjs";
import { HistoryBuffer } from "./HistoryBuffer.mjs";
import { maybeCaptureParent, startCapturingParents, stopCapturingParents } from "./capture.mjs";
import { GLOBAL_START_EPOCH } from "./constants.mjs";
import { EMPTY_ARRAY, equals, haveParentsChanged, singleton } from "./helpers.mjs";
import { getGlobalEpoch, getIsReacting, getReactionEpoch } from "./transactions.mjs";
import { RESET_VALUE } from "./types.mjs";
import { logComputedGetterWarning } from "./warnings.mjs";
const UNINITIALIZED = Symbol.for("com.tldraw.state/UNINITIALIZED");
function isUninitialized(value) {
return value === UNINITIALIZED;
}
const WithDiff = singleton(
"WithDiff",
() => (class WithDiff {
constructor(value, diff) {
this.value = value;
this.diff = diff;
}
})
);
function withDiff(value, diff) {
return new WithDiff(value, diff);
}
class __UNSAFE__Computed {
constructor(name, derive, options) {
this.name = name;
this.derive = derive;
if (options?.historyLength) {
this.historyBuffer = new HistoryBuffer(options.historyLength);
}
this.computeDiff = options?.computeDiff;
this.isEqual = options?.isEqual ?? equals;
}
lastChangedEpoch = GLOBAL_START_EPOCH;
lastTraversedEpoch = GLOBAL_START_EPOCH;
__debug_ancestor_epochs__ = null;
/**
* The epoch when the reactor was last checked.
*/
lastCheckedEpoch = GLOBAL_START_EPOCH;
parentSet = new ArraySet();
parents = [];
parentEpochs = [];
children = new ArraySet();
// eslint-disable-next-line no-restricted-syntax
get isActivelyListening() {
return !this.children.isEmpty;
}
historyBuffer;
// The last-computed value of this signal.
state = UNINITIALIZED;
// If the signal throws an error we stash it so we can rethrow it on the next get()
error = null;
computeDiff;
isEqual;
__unsafe__getWithoutCapture(ignoreErrors) {
const isNew = this.lastChangedEpoch === GLOBAL_START_EPOCH;
const globalEpoch = getGlobalEpoch();
if (!isNew && (this.lastCheckedEpoch === globalEpoch || this.isActivelyListening && getIsReacting() && this.lastTraversedEpoch < getReactionEpoch() || !haveParentsChanged(this))) {
this.lastCheckedEpoch = globalEpoch;
if (this.error) {
if (!ignoreErrors) {
throw this.error.thrownValue;
} else {
return this.state;
}
} else {
return this.state;
}
}
try {
startCapturingParents(this);
const result = this.derive(this.state, this.lastCheckedEpoch);
const newState = result instanceof WithDiff ? result.value : result;
const isUninitialized2 = this.state === UNINITIALIZED;
if (isUninitialized2 || !this.isEqual(newState, this.state)) {
if (this.historyBuffer && !isUninitialized2) {
const diff = result instanceof WithDiff ? result.diff : void 0;
this.historyBuffer.pushEntry(
this.lastChangedEpoch,
getGlobalEpoch(),
diff ?? this.computeDiff?.(this.state, newState, this.lastCheckedEpoch, getGlobalEpoch()) ?? RESET_VALUE
);
}
this.lastChangedEpoch = getGlobalEpoch();
this.state = newState;
}
this.error = null;
this.lastCheckedEpoch = getGlobalEpoch();
return this.state;
} catch (e) {
if (this.state !== UNINITIALIZED) {
this.state = UNINITIALIZED;
this.lastChangedEpoch = getGlobalEpoch();
}
this.lastCheckedEpoch = getGlobalEpoch();
if (this.historyBuffer) {
this.historyBuffer.clear();
}
this.error = { thrownValue: e };
if (!ignoreErrors) throw e;
return this.state;
} finally {
stopCapturingParents();
}
}
get() {
try {
return this.__unsafe__getWithoutCapture();
} finally {
maybeCaptureParent(this);
}
}
getDiffSince(epoch) {
this.__unsafe__getWithoutCapture(true);
maybeCaptureParent(this);
if (epoch >= this.lastChangedEpoch) {
return EMPTY_ARRAY;
}
return this.historyBuffer?.getChangesSince(epoch) ?? RESET_VALUE;
}
}
const _Computed = singleton("Computed", () => __UNSAFE__Computed);
function computedMethodLegacyDecorator(options = {}, _target, key, descriptor) {
const originalMethod = descriptor.value;
const derivationKey = Symbol.for("__@tldraw/state__computed__" + key);
descriptor.value = function() {
let d = this[derivationKey];
if (!d) {
d = new _Computed(key, originalMethod.bind(this), options);
Object.defineProperty(this, derivationKey, {
enumerable: false,
configurable: false,
writable: false,
value: d
});
}
return d.get();
};
descriptor.value[isComputedMethodKey] = true;
return descriptor;
}
function computedGetterLegacyDecorator(options = {}, _target, key, descriptor) {
const originalMethod = descriptor.get;
const derivationKey = Symbol.for("__@tldraw/state__computed__" + key);
descriptor.get = function() {
let d = this[derivationKey];
if (!d) {
d = new _Computed(key, originalMethod.bind(this), options);
Object.defineProperty(this, derivationKey, {
enumerable: false,
configurable: false,
writable: false,
value: d
});
}
return d.get();
};
return descriptor;
}
function computedMethodTc39Decorator(options, compute, context) {
assert(context.kind === "method", "@computed can only be used on methods");
const derivationKey = Symbol.for("__@tldraw/state__computed__" + String(context.name));
const fn = function() {
let d = this[derivationKey];
if (!d) {
d = new _Computed(String(context.name), compute.bind(this), options);
Object.defineProperty(this, derivationKey, {
enumerable: false,
configurable: false,
writable: false,
value: d
});
}
return d.get();
};
fn[isComputedMethodKey] = true;
return fn;
}
function computedDecorator(options = {}, args) {
if (args.length === 2) {
const [originalMethod, context] = args;
return computedMethodTc39Decorator(options, originalMethod, context);
} else {
const [_target, key, descriptor] = args;
if (descriptor.get) {
logComputedGetterWarning();
return computedGetterLegacyDecorator(options, _target, key, descriptor);
} else {
return computedMethodLegacyDecorator(options, _target, key, descriptor);
}
}
}
const isComputedMethodKey = "@@__isComputedMethod__@@";
function getComputedInstance(obj, propertyName) {
const key = Symbol.for("__@tldraw/state__computed__" + propertyName.toString());
let inst = obj[key];
if (!inst) {
const val = obj[propertyName];
if (typeof val === "function" && val[isComputedMethodKey]) {
val.call(obj);
}
inst = obj[key];
}
return inst;
}
function computed() {
if (arguments.length === 1) {
const options = arguments[0];
return (...args) => computedDecorator(options, args);
} else if (typeof arguments[0] === "string") {
return new _Computed(arguments[0], arguments[1], arguments[2]);
} else {
return computedDecorator(void 0, arguments);
}
}
function isComputed(value) {
return value && value instanceof _Computed;
}
export {
UNINITIALIZED,
WithDiff,
_Computed,
computed,
getComputedInstance,
isComputed,
isUninitialized,
withDiff
};
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