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createMemoryHistory.js
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createMemoryHistory.js
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import { createPath } from './PathUtils.js';
import { createLocation } from './LocationUtils.js';
import createTransitionManager from './createTransitionManager.js';
import warning from './warning.js';
function clamp(n, lowerBound, upperBound) {
return Math.min(Math.max(n, lowerBound), upperBound);
}
/**
* Creates a history object that stores locations in memory.
*/
function createMemoryHistory(props = {}) {
const {
getUserConfirmation,
initialEntries = ['/'],
initialIndex = 0,
keyLength = 6
} = props;
const transitionManager = createTransitionManager();
function setState(nextState) {
Object.assign(history, nextState);
history.length = history.entries.length;
transitionManager.notifyListeners(history.location, history.action);
}
function createKey() {
return Math.random()
.toString(36)
.substr(2, keyLength);
}
const index = clamp(initialIndex, 0, initialEntries.length - 1);
const entries = initialEntries.map(entry =>
typeof entry === 'string'
? createLocation(entry, undefined, createKey())
: createLocation(entry, undefined, entry.key || createKey())
);
// Public interface
const createHref = createPath;
function push(path, state) {
warning(
!(
typeof path === 'object' &&
path.state !== undefined &&
state !== undefined
),
'You should avoid providing a 2nd state argument to push when the 1st ' +
'argument is a location-like object that already has state; it is ignored'
);
const action = 'PUSH';
const location = createLocation(path, state, createKey(), history.location);
transitionManager.confirmTransitionTo(
location,
action,
getUserConfirmation,
ok => {
if (!ok) return;
const prevIndex = history.index;
const nextIndex = prevIndex + 1;
const nextEntries = history.entries.slice(0);
if (nextEntries.length > nextIndex) {
nextEntries.splice(
nextIndex,
nextEntries.length - nextIndex,
location
);
} else {
nextEntries.push(location);
}
setState({
action,
location,
index: nextIndex,
entries: nextEntries
});
}
);
}
function replace(path, state) {
warning(
!(
typeof path === 'object' &&
path.state !== undefined &&
state !== undefined
),
'You should avoid providing a 2nd state argument to replace when the 1st ' +
'argument is a location-like object that already has state; it is ignored'
);
const action = 'REPLACE';
const location = createLocation(path, state, createKey(), history.location);
transitionManager.confirmTransitionTo(
location,
action,
getUserConfirmation,
ok => {
if (!ok) return;
history.entries[history.index] = location;
setState({ action, location });
}
);
}
function go(n) {
const nextIndex = clamp(history.index + n, 0, history.entries.length - 1);
const action = 'POP';
const location = history.entries[nextIndex];
transitionManager.confirmTransitionTo(
location,
action,
getUserConfirmation,
ok => {
if (ok) {
setState({
action,
location,
index: nextIndex
});
} else {
// Mimic the behavior of DOM histories by
// causing a render after a cancelled POP.
setState();
}
}
);
}
function goBack() {
go(-1);
}
function goForward() {
go(1);
}
function canGo(n) {
const nextIndex = history.index + n;
return nextIndex >= 0 && nextIndex < history.entries.length;
}
function block(prompt = false) {
return transitionManager.setPrompt(prompt);
}
function listen(listener) {
return transitionManager.appendListener(listener);
}
const history = {
length: entries.length,
action: 'POP',
location: entries[index],
index,
entries,
createHref,
push,
replace,
go,
goBack,
goForward,
canGo,
block,
listen
};
return history;
}
export default createMemoryHistory;