refactoring; pre-compiling regular expressions to improve performance

Author: AleksandrRogov

src/client/helpers/parseBatchResponse.ts

@@ -0,0 +1,147 @@
+import { DynamicsWebApiError, ErrorHelper } from "../../helpers/ErrorHelper";
+import {
+    BATCH_RESPONSE_HEADERS_REGEX,
+    LINE_ENDING_REGEX,
+    HTTP_STATUS_REGEX,
+    TEXT_REGEX,
+    CONTENT_TYPE_PLAIN_REGEX,
+    ODATA_ENTITYID_REGEX,
+    extractUuidFromUrl,
+} from "../../helpers/Regex";
+import { handleJsonResponse, handlePlainResponse } from "./parseResponse";
+
+//partially taken from http://olingo.apache.org/doc/javascript/apidoc/batch.js.html
+function parseBatchHeaders(text: string): any {
+    const ctx = { position: 0 };
+    const headers: Record<string, string> = {};
+    let parts: RegExpExecArray | null;
+    let line: string | null;
+    let pos: number;
+
+    do {
+        pos = ctx.position;
+        line = readLine(text, ctx);
+        if (!line) break; //if the line is empty, then it is the end of the headers
+        parts = BATCH_RESPONSE_HEADERS_REGEX.exec(line);
+        if (parts !== null) {
+            headers[parts[1].toLowerCase()] = parts[2];
+        } else {
+            // Whatever was found is not a header, so reset the context position.
+            ctx.position = pos;
+        }
+    } while (line && parts);
+
+    return headers;
+}
+
+//partially taken from http://olingo.apache.org/doc/javascript/apidoc/batch.js.html
+function readLine(text: string, ctx: { position: number }): string | null {
+    return readTo(text, ctx, LINE_ENDING_REGEX);
+}
+
+//partially taken from http://olingo.apache.org/doc/javascript/apidoc/batch.js.html
+function readTo(text: string, ctx: { position: number }, searchRegTerm: RegExp): string | null {
+    const start = ctx.position || 0;
+    const slicedText = text.slice(start);
+    const match = searchRegTerm.exec(slicedText);
+    if (!match) {
+        return null;
+    }
+    const end = start + match.index;
+    ctx.position = end + match[0].length;
+    return text.substring(start, end);
+}
+
+//partially taken from https://github.com/emiltholin/google-api-batch-utils
+function getHttpStatus(response: string) {
+    const parts = HTTP_STATUS_REGEX.exec(response);
+    //todo: add error handler for httpStatus and httpStatusMessage; remove "!" operator
+    return { httpStatusString: parts![0], httpStatus: parseInt(parts![1]), httpStatusMessage: parts![2].trim() };
+}
+
+function getPlainContent(response: string) {
+    // Reset the lastIndex property to ensure correct matching
+    HTTP_STATUS_REGEX.lastIndex = 0;
+
+    const textReg = TEXT_REGEX.exec(response.trim());
+    return textReg?.length ? textReg[0] : undefined;
+}
+
+function handlePlainContent(batchResponse: string, parseParams: any, requestNumber: number): any {
+    const plainContent = getPlainContent(batchResponse);
+    return handlePlainResponse(plainContent);
+}
+
+function handleEmptyContent(batchResponse: string, parseParams: any, requestNumber: number): any {
+    if (parseParams?.[requestNumber]?.valueIfEmpty !== undefined) {
+        return parseParams[requestNumber].valueIfEmpty;
+    } else {
+        const entityUrl = ODATA_ENTITYID_REGEX.exec(batchResponse);
+        return extractUuidFromUrl(entityUrl?.[0]) ?? undefined;
+    }
+}
+
+function processBatchPart(batchResponse: string, parseParams: any, requestNumber: number): any {
+    const { httpStatusString, httpStatus, httpStatusMessage } = getHttpStatus(batchResponse);
+    const responseData = batchResponse.substring(batchResponse.indexOf("{"), batchResponse.lastIndexOf("}") + 1);
+
+    //if the batch part does not contain a json response, parse it as plain or empty content
+    if (!responseData) {
+        if (CONTENT_TYPE_PLAIN_REGEX.test(batchResponse)) {
+            return handlePlainContent(batchResponse, parseParams, requestNumber);
+        }
+
+        return handleEmptyContent(batchResponse, parseParams, requestNumber);
+    }
+
+    //parse json data
+    const parsedResponse = handleJsonResponse(responseData, parseParams, requestNumber);
+
+    if (httpStatus < 400) {
+        return parsedResponse;
+    }
+
+    //handle error
+    const responseHeaders = parseBatchHeaders(
+        batchResponse.substring(batchResponse.indexOf(httpStatusString) + httpStatusString.length + 1, batchResponse.indexOf("{"))
+    );
+
+    return ErrorHelper.handleHttpError(parsedResponse, {
+        status: httpStatus,
+        statusText: httpStatusMessage,
+        statusMessage: httpStatusMessage,
+        headers: responseHeaders,
+    });
+}
+
+/**
+ *
+ * @param {string} response - response that needs to be parsed
+ * @param {Array} parseParams - parameters for parsing the response
+ * @param {Number} [requestNumber] - number of the request
+ * @returns {any} parsed batch response
+ */
+export function parseBatchResponse(response: string, parseParams: any, requestNumber: number = 0): (string | undefined | DynamicsWebApiError | Number)[] {
+    // Not the same delimiter in the response as we specify ourselves in the request,
+    // so we have to extract it.
+    const delimiter = response.substring(0, response.search(LINE_ENDING_REGEX));
+    const batchResponseParts = response.split(delimiter);
+    // The first part will always be an empty string. Just remove it.
+    batchResponseParts.shift();
+    // The last part will be the "--". Just remove it.
+    batchResponseParts.pop();
+
+    let result: (string | undefined | DynamicsWebApiError | Number)[] = [];
+    for (let part of batchResponseParts) {
+        if (part.indexOf("--changesetresponse_") === -1) {
+            result.push(processBatchPart(part, parseParams, requestNumber++));
+            continue;
+        }
+
+        part = part.trim();
+        const batchToProcess = part.substring(part.search(LINE_ENDING_REGEX) + 1).trim();
+        result = result.concat(parseBatchResponse(batchToProcess, parseParams, requestNumber++));
+    }
+
+    return result;
+}