state-manager.js
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export var Html5QrcodeScannerState;
(function (Html5QrcodeScannerState) {
Html5QrcodeScannerState[Html5QrcodeScannerState["UNKNOWN"] = 0] = "UNKNOWN";
Html5QrcodeScannerState[Html5QrcodeScannerState["NOT_STARTED"] = 1] = "NOT_STARTED";
Html5QrcodeScannerState[Html5QrcodeScannerState["SCANNING"] = 2] = "SCANNING";
Html5QrcodeScannerState[Html5QrcodeScannerState["PAUSED"] = 3] = "PAUSED";
})(Html5QrcodeScannerState || (Html5QrcodeScannerState = {}));
class StateManagerImpl {
constructor() {
this.state = Html5QrcodeScannerState.NOT_STARTED;
this.onGoingTransactionNewState = Html5QrcodeScannerState.UNKNOWN;
}
directTransition(newState) {
this.failIfTransitionOngoing();
this.validateTransition(newState);
this.state = newState;
}
startTransition(newState) {
this.failIfTransitionOngoing();
this.validateTransition(newState);
this.onGoingTransactionNewState = newState;
return this;
}
execute() {
if (this.onGoingTransactionNewState
=== Html5QrcodeScannerState.UNKNOWN) {
throw "Transaction is already cancelled, cannot execute().";
}
const tempNewState = this.onGoingTransactionNewState;
this.onGoingTransactionNewState = Html5QrcodeScannerState.UNKNOWN;
this.directTransition(tempNewState);
}
cancel() {
if (this.onGoingTransactionNewState
=== Html5QrcodeScannerState.UNKNOWN) {
throw "Transaction is already cancelled, cannot cancel().";
}
this.onGoingTransactionNewState = Html5QrcodeScannerState.UNKNOWN;
}
getState() {
return this.state;
}
failIfTransitionOngoing() {
if (this.onGoingTransactionNewState
!== Html5QrcodeScannerState.UNKNOWN) {
throw "Cannot transition to a new state, already under transition";
}
}
validateTransition(newState) {
switch (this.state) {
case Html5QrcodeScannerState.UNKNOWN:
throw "Transition from unknown is not allowed";
case Html5QrcodeScannerState.NOT_STARTED:
this.failIfNewStateIs(newState, [Html5QrcodeScannerState.PAUSED]);
break;
case Html5QrcodeScannerState.SCANNING:
break;
case Html5QrcodeScannerState.PAUSED:
break;
}
}
failIfNewStateIs(newState, disallowedStatesToTransition) {
for (const disallowedState of disallowedStatesToTransition) {
if (newState === disallowedState) {
throw `Cannot transition from ${this.state} to ${newState}`;
}
}
}
}
export class StateManagerProxy {
constructor(stateManager) {
this.stateManager = stateManager;
}
startTransition(newState) {
return this.stateManager.startTransition(newState);
}
directTransition(newState) {
this.stateManager.directTransition(newState);
}
getState() {
return this.stateManager.getState();
}
canScanFile() {
return this.stateManager.getState() === Html5QrcodeScannerState.NOT_STARTED;
}
isScanning() {
return this.stateManager.getState() !== Html5QrcodeScannerState.NOT_STARTED;
}
isStrictlyScanning() {
return this.stateManager.getState() === Html5QrcodeScannerState.SCANNING;
}
isPaused() {
return this.stateManager.getState() === Html5QrcodeScannerState.PAUSED;
}
}
export class StateManagerFactory {
static create() {
return new StateManagerProxy(new StateManagerImpl());
}
}
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