Move isArqueroTable to fix circular dependency (#336)

Author: libbey-observable

src/arquero.js

@@ -0,0 +1,4 @@
+export function isArqueroTable(value) {
+  // Arquero tables have a `toArrowBuffer` function
+  return value && typeof value.toArrowBuffer === "function";
+}

src/duckdb.js

@@ -1,8 +1,8 @@
+import {isArqueroTable} from "./arquero.js";
 import {getArrowTableSchema, isArrowTable, loadArrow} from "./arrow.js";
 import {duckdb} from "./dependencies.js";
 import {FileAttachment} from "./fileAttachment.js";
 import {cdn} from "./require.js";
-import {isArqueroTable} from "./table.js";
 
 // Adapted from https://observablehq.com/@cmudig/duckdb-client
 // Copyright 2021 CMU Data Interaction Group

src/index.js

@@ -1,12 +1,12 @@
 export {FileAttachments, AbstractFile} from "./fileAttachment.js";
 export {Library} from "./library.js";
 export {getArrowTableSchema, isArrowTable} from "./arrow.js";
+export {isArqueroTable} from "./arquero.js";
 export {
   makeQueryTemplate,
   loadDataSource,
   arrayIsPrimitive,
   isDataArray,
   isDatabaseClient,
-  isArqueroTable,
   __table as applyDataTableOperations
 } from "./table.js";

src/table.js

@@ -1,5 +1,6 @@
 import {ascending, descending, reverse} from "d3-array";
 import {FileAttachment} from "./fileAttachment.js";
+import {isArqueroTable} from "./arquero.js";
 import {isArrowTable, loadArrow} from "./arrow.js";
 import {DuckDBClient} from "./duckdb.js";
 
@@ -141,11 +142,6 @@ function isTypedArray(value) {
   );
 }
 
-export function isArqueroTable(value) {
-  // Arquero tables have a `toArrowBuffer` function
-  return value && typeof value.toArrowBuffer === "function";
-}
-
 // __query is used by table cells; __query.sql is used by SQL cells.
 export const __query = Object.assign(
   async (source, operations, invalidation, name) => {