[MLv2] Add TypeScript wrappers for MLv2 expression methods (#32595)

* Add `ExpressionClause` type

* Add TypeScript wrappers for expression methods

* Export expression wrappers

* Fix `expression` method

frontend/src/metabase-lib/expression.ts

+import * as ML from "cljs/metabase.lib.js";
+import type { ColumnMetadata, ExpressionClause, Query } from "./types";
+
+export function expression(
+  query: Query,
+  stageIndex: number,
+  expressionName: string,
+  clause: ExpressionClause,
+): Query {
+  return ML.expression(query, stageIndex, expressionName, clause);
+}
+
+export function expressions(
+  query: Query,
+  stageIndex: number,
+): ExpressionClause[] {
+  return ML.expressions(query, stageIndex);
+}
+
+export function expressionableColumns(
+  query: Query,
+  stageIndex: number,
+  expressionPosition: number,
+): ColumnMetadata[] {
+  return ML.expressionable_columns(query, stageIndex, expressionPosition);
+}

frontend/src/metabase-lib/types.ts

@@ -30,6 +30,9 @@ export type AggregationOperator = unknown & {
 declare const BreakoutClause: unique symbol;
 export type BreakoutClause = unknown & { _opaque: typeof BreakoutClause };
 
+declare const ExpressionClause: unique symbol;
+export type ExpressionClause = unknown & { _opaque: typeof ExpressionClause };
+
 declare const OrderByClause: unique symbol;
 export type OrderByClause = unknown & { _opaque: typeof OrderByClause };
 
@@ -41,6 +44,7 @@ export type FilterClause = unknown & { _opaque: typeof FilterClause };
 export type Clause =
   | AggregationClause
   | BreakoutClause
+  | ExpressionClause
   | FilterClause
   | OrderByClause;
 

frontend/src/metabase-lib/v2.ts

@@ -9,6 +9,7 @@ export * from "./column_types";
 export * from "./common";
 export * from "./comparison";
 export * from "./database";
+export * from "./expression";
 export * from "./fields";
 export * from "./filter";
 export * from "./join";