Merge pull request #5677 from poorna2152/regex_find

Add BBE for `Regexp` find operations

examples/index.json

@@ -1223,6 +1223,13 @@
         "verifyBuild": true,
         "verifyOutput": true,
         "isLearnByExample": true
+      },
+      {
+        "name": "RegExp find operations",
+        "url": "regexp-find-operations",
+        "verifyBuild": true,
+        "verifyOutput": true,
+        "isLearnByExample": true
       }
     ]
   },

examples/regexp-find-operations/regexp_find_operations.bal

@@ -0,0 +1,63 @@
+import ballerina/io;
+import ballerina/lang.regexp;
+
+public function main() returns error? {
+    string logContent = string `
+        2024-09-19 10:02:01 WARN  [UserLogin] - Failed login attempt for user: johndoe
+        2024-09-19 10:03:17 ERROR [Database] - Connection to database timed out
+        2024-09-19 10:04:05 WARN  [RequestHandler] - Response time exceeded threshold for /api/v1/users
+        2024-09-19 10:05:45 INFO  [Scheduler] - Scheduled task started: Data backup
+        2024-09-19 10:06:10 ERROR [Scheduler] - Failed to start data backup: Permission denied
+        2024-09-19 10:11:55 INFO  [Security] - Security scan completed, no issues found
+        2024-09-19 10:12:30 ERROR [RequestHandler] - 404 Not Found: /api/v1/products`;
+
+    // Regular expression to match error logs with three groups:
+    // 1. Timestamp (e.g., 2024-09-19 10:03:17).
+    // 2. Component (e.g., Database, Scheduler).
+    // 3. Log message (e.g., Connection to database timed out).
+    string:RegExp errorLogPattern = re `(\d{4}-\d{2}-\d{2} \d{2}:\d{2}:\d{2}) ERROR \[(\w+)\]\s-\s(.*)`;
+
+    // Retrieve the first error log from `logContent`.
+    regexp:Span? firstErrorLog = errorLogPattern.find(logContent);
+    if firstErrorLog == () {
+        io:println("Failed to find a error log");
+        return;
+    }
+    io:println("First error log: ", firstErrorLog.substring());
+
+    // Retrieve all error logs from the `logContent`.
+    regexp:Span[] allErrorLogs = errorLogPattern.findAll(logContent);
+    io:println("\nAll error logs:");
+    foreach regexp:Span errorLog in allErrorLogs {
+        io:println(errorLog.substring());
+    }
+
+    // Retrieve groups (timestamp, component, message) from the first error log.
+    regexp:Groups? firstErrorLogGroups = errorLogPattern.findGroups(logContent);
+    if firstErrorLogGroups == () {
+        io:println("Failed to find groups in first error log");
+        return;
+    }
+    io:println("\nGroups within first error log:");
+    check printGroupsWithinLog(firstErrorLogGroups);
+
+    // Retrieve groups from all error logs.
+    regexp:Groups[] allErrorLogGroups = errorLogPattern.findAllGroups(logContent);
+    io:println("\nGroups in all error logs");
+    foreach regexp:Groups logGroup in allErrorLogGroups {
+        check printGroupsWithinLog(logGroup);
+    }
+}
+
+function printGroupsWithinLog(regexp:Groups logGroup) returns error? {
+    // The first element in the `logGroup` is the entire matched string.
+    // The subsequent elements in `logGroup` represent the captured groups 
+    // (timestamp, component, message).
+    string timestamp = (check logGroup[1].ensureType(regexp:Span)).substring();
+    string component = (check logGroup[2].ensureType(regexp:Span)).substring();
+    string logMessage = (check logGroup[3].ensureType(regexp:Span)).substring();
+
+    io:println("Timestamp: ", timestamp);
+    io:println("Component: ", component);
+    io:println("Message: ", logMessage);
+}

examples/regexp-find-operations/regexp_find_operations.md

@@ -0,0 +1,12 @@
+# RegExp find operations
+
+The `RegExp` type provides a set of langlib functions to find patterns within strings. These functions enable efficient pattern matching, grouping, and extraction based on specific regular expressions.
+
+::: code regexp_find_operations.bal :::
+
+::: out regexp_find_operations.out :::
+
+## Related links
+- [RegExp type](/learn/by-example/regexp-type)
+- [RegExp API Docs](https://lib.ballerina.io/ballerina/lang.regexp)
+- [string API Docs](https://lib.ballerina.io/ballerina/lang.string)

examples/regexp-find-operations/regexp_find_operations.metatags

@@ -0,0 +1,2 @@
+description: This BBE demonstrates how to use the regexp langlib functions relevant to regex find operations.
+keywords: ballerina, ballerina by example, bbe, regexp, RegExp, regex, regular expressions, ballerina regex functions, regexp langlib functions, find, findAll, findGroups, findAllGroups

examples/regexp-find-operations/regexp_find_operations.out

@@ -0,0 +1,23 @@
+$ bal run regexp_find_operations.bal
+First error log: 2024-09-19 10:03:17 ERROR [Database] - Connection to database timed out
+
+All error logs:
+2024-09-19 10:03:17 ERROR [Database] - Connection to database timed out
+2024-09-19 10:06:10 ERROR [Scheduler] - Failed to start data backup: Permission denied
+2024-09-19 10:12:30 ERROR [RequestHandler] - 404 Not Found: /api/v1/products
+
+Groups within first error log:
+Timestamp: 2024-09-19 10:03:17
+Component: Database
+Message: Connection to database timed out
+
+Groups in all error logs
+Timestamp: 2024-09-19 10:03:17
+Component: Database
+Message: Connection to database timed out
+Timestamp: 2024-09-19 10:06:10
+Component: Scheduler
+Message: Failed to start data backup: Permission denied
+Timestamp: 2024-09-19 10:12:30
+Component: RequestHandler
+Message: 404 Not Found: /api/v1/products