Swap lz4 library

Add rowset slicing

Author: gionatamettifogo

package-lock.json

@@ -1,6 +1,6 @@
 {
   "name": "sqlitecloud-js",
-  "version": "0.0.19-beta",
+  "version": "0.0.20-beta",
   "description": "SQLiteCloud drivers for Typescript/Javascript in edge, web and node clients",
   "main": "./lib/index.js",
   "types": "./lib/index.d.ts",
@@ -42,7 +42,7 @@
   "homepage": "https://github.com/sqlitecloud/sqlitecloud-js#readme",
   "dependencies": {
     "eventemitter3": "^5.0.1",
-    "lz4": "^0.6.5"
+    "lz4js": "^0.2.0"
   },
   "devDependencies": {
     "@types/jest": "^29.5.7",

package.json

@@ -3,7 +3,8 @@
  */
 
 import tls from 'tls'
-import lz4 from 'lz4'
+
+const lz4 = require('lz4js')
 
 import { SQLiteCloudConfig, SQLCloudRowsetMetadata, SQLiteCloudError, SQLiteCloudDataTypes, ErrorCallback, ResultsCallback } from './types'
 import { SQLiteCloudRowset } from './rowset'

src/connection.ts

@@ -101,4 +101,23 @@ export class SQLiteCloudRowset extends Array<SQLiteCloudRow> {
     }
     return this.#data[row * this.numberOfColumns + column]
   }
+
+  /** Returns a subset of rows from this rowset */
+  slice(start?: number, end?: number): SQLiteCloudRow[] {
+    start = start && start > 0 ? start : 0
+    if (end === undefined) {
+      end = this.numberOfRows
+    } else if (end < 0) {
+      end = this.numberOfRows + end
+    }
+    if (end < start) {
+      end = start
+    } else if (end > this.numberOfRows) {
+      end = this.numberOfRows
+    }
+
+    const slicedData = this.#data.slice(start * this.numberOfColumns, end * this.numberOfColumns)
+    const slicedMetadata = { ...this.#metadata, numberOfRows: end - start }
+    return new SQLiteCloudRowset(slicedMetadata, slicedData)
+  }
 }

src/rowset.ts

@@ -34,6 +34,30 @@ describe('rowset', () => {
     })
   })
 
+  it('can be sliced like an array', done => {
+    const connection = getChinookConnection()
+    connection.sendCommands('SELECT * FROM tracks LIMIT 50;', (error, rowset) => {
+      expect(rowset).toBeInstanceOf(SQLiteCloudRowset)
+      expect(rowset.numberOfColumns).toBe(9)
+      expect(rowset.numberOfRows).toBe(50)
+      expect(Array.isArray(rowset)).toBeTruthy()
+      expect(rowset).toHaveLength(50)
+
+      const sliced = rowset.slice(10, 20)
+      expect(sliced).toHaveLength(10)
+      expect(sliced[0]).toMatchObject(rowset[10])
+
+      // slice more than actually exists!
+      const largerSlice = rowset.slice(10, 100)
+      expect(largerSlice).toHaveLength(40)
+      expect(largerSlice[0]).toMatchObject(rowset[10])
+      expect(largerSlice[39]).toMatchObject(rowset[49])
+
+      connection.close()
+      done()
+    })
+  })
+
   it('contains basic metadata', done => {
     const connection = getChinookConnection()
     connection.sendCommands('SELECT * FROM tracks LIMIT 10;', (error, rowset) => {