rxdb
Version:
A local-first realtime NoSQL Database for JavaScript applications - https://rxdb.info/
63 lines (60 loc) • 1.8 kB
JavaScript
import { newRxError } from "../../rx-error.js";
/**
* Parses the full revision.
* Do NOT use this if you only need the revision height,
* then use getHeightOfRevision() instead which is faster.
*/
export function parseRevision(revision) {
var dashIndex = revision.indexOf('-');
if (dashIndex === -1) {
throw new Error('malformatted revision: ' + revision);
}
var height;
if (dashIndex === 1) {
height = revision.charCodeAt(0) - 48;
} else {
height = 0;
for (var i = 0; i < dashIndex; i++) {
height = height * 10 + (revision.charCodeAt(i) - 48);
}
}
return {
height,
hash: revision.substring(dashIndex + 1)
};
}
/**
* @hotPath Performance is very important here
* because we need to parse the revision height very often.
* Uses indexOf + charCodeAt for maximum performance.
* Single-digit heights (most common) use a fast path
* that avoids parseInt entirely.
*/
export function getHeightOfRevision(revision) {
var dashIndex = revision.indexOf('-');
if (dashIndex === -1) {
throw newRxError('SNH', {
args: {
revision
}
});
}
// Fast path for single-digit revision heights (most common case)
if (dashIndex === 1) {
return revision.charCodeAt(0) - 48;
}
// Manual number parsing for multi-digit heights (avoids parseInt + substring)
var num = 0;
for (var i = 0; i < dashIndex; i++) {
num = num * 10 + (revision.charCodeAt(i) - 48);
}
return num;
}
/**
* Creates the next write revision for a given document.
*/
export function createRevision(databaseInstanceToken, previousDocData) {
var newRevisionHeight = !previousDocData ? 1 : getHeightOfRevision(previousDocData._rev) + 1;
return newRevisionHeight + '-' + databaseInstanceToken;
}
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