lookingAt (Function)
Matches the input.sequence from the beginning against the regex pattern, and unlike regex:matches() it does not require that the entire input.sequence be matched.
Syntax
<BOOL> regex:lookingAt(<STRING> regex, <STRING> input.sequence)
Query Parameters
| Name | Description | Default Value | Possible Data Types | Optional | Dynamic |
|---|---|---|---|---|---|
| regex | A regular expression. For example, \d\d(.*)gdn. | STRING | No | Yes | |
| input.sequence | The input sequence to be matched with the regular expression. For example, 21 products are produced by gdn. | STRING | No | Yes |
Example 1
@info(name = 'regexLookingAtExample1')
SELECT regex:lookingAt('\\d\\d(.*)(gdn.*)', '21 products are produced by gdn currently in Sri Lanka') AS lookingAtResult;
The regexLookingAtExample1 demonstrates the use of the regex:lookingAt() function to check if the input string matches the provided regular expression pattern from the beginning. In this example, the input string is '21 products are produced by gdn currently in Sri Lanka', and the regular expression pattern is \\d\\d(.*)(gdn.*). The function returns true because the input string matches the pattern from the beginning.
Example 2
@info(name = 'regexLookingAtExample2')
SELECT regex:lookingAt('gdn(.*)middleware(.*)', 'sample test string and gdn is situated in trace and it''s a middleware company') AS lookingAtResult;
The regexLookingAtExample2 demonstrates the use of the regex:lookingAt() function to check if the input string matches the provided regular expression pattern from the beginning. In this example, the input string is 'sample test string and gdn is situated in trace and it's a middleware company', and the regular expression pattern is gdn(.*)middleware(.*). The function returns false because the input string does not match the pattern from the beginning.
Example 3
CREATE STREAM InputStream (eventTime long, inputText string, regexPattern string);
CREATE SINK STREAM OutputStream (eventTime long, lookingAtRegex bool);
@info(name = 'regexLookingAtStreamWorker')
INSERT INTO OutputStream
SELECT eventTime, regex:lookingAt(regexPattern, inputText) AS lookingAtRegex
FROM InputStream;
The regexLookingAtStreamWorker processes events from the InputStream and uses the regex:lookingAt() function to check if the inputText attribute matches the specified regexPattern attribute from the beginning of the string. The query outputs the eventTime and a boolean value lookingAtRegex for each event to the OutputStream. The boolean value is true if the input string matches the regular expression pattern from the beginning, and false otherwise.