Implements tryEval.

data-extraction/src/js/api/DataExtractorApi.ts

@@ -17,10 +17,12 @@ export interface DataExtractorApi {
 	registerExtractors(extractors: DataExtractor<ExtractedData>[]): void;
 
 	/**
-	 * Extracts data from `value`.
+	 * Extracts data from the result of `valueFn`.
+	 * @valueFn a function returning the value to extract the data from.
+	 * Is a function so that it's evaluation can depend on `evalFn`.
 	 */
 	getData(
-		value: unknown,
+		valueFn: () => unknown,
 		evalFn: <T>(expression: string) => T,
 		preferredDataExtractorId: string | undefined
 	): JSONString<DataResult>;

data-extraction/src/js/api/DataExtractorApiImpl.ts

@@ -10,6 +10,8 @@ import { ExtractedData, DataExtractorInfo } from "../../DataExtractionResult";
 import { registerDefaultDataExtractors } from "./default-extractors";
 
 export class DataExtractorApiImpl implements DataExtractorApi {
+	public static lastEvalFn: (<T>(expression: string) => T) | undefined;
+
 	private readonly extractors = new Map<
 		string,
 		DataExtractor<ExtractedData>
@@ -34,7 +36,7 @@ export class DataExtractorApiImpl implements DataExtractorApi {
 	}
 
 	public getData(
-		value: unknown,
+		valueFn: () => unknown,
 		evalFn: <T>(expression: string) => T,
 		preferredDataExtractorId: string | undefined
 	): JSONString<DataResult> {
@@ -45,6 +47,10 @@ export class DataExtractorApiImpl implements DataExtractorApi {
 			},
 		};
 
+		DataExtractorApiImpl.lastEvalFn = evalFn;
+		const value = valueFn();
+		DataExtractorApiImpl.lastEvalFn = undefined;
+
 		for (const e of this.extractors.values()) {
 			e.getExtractions(value, extractionCollector, { evalFn });
 		}
@@ -85,6 +91,7 @@ export class DataExtractorApiImpl implements DataExtractorApi {
 	}
 
 	public registerDefaultExtractors(preferExisting: boolean = false): void {
+		// TODO consider preferExisting
 		registerDefaultDataExtractors(this);
 	}
 }