Google to unleash code search site

Google is today expected to launch a website it says will let programmers search billions of lines of code.

The service - Google Code Search - conceived by the Google Labs early technology group, will crawl publicly available code, most of which is made available through open source projects. The search and indexing can cover code on web pages as well as code that resides in compressed files, according to Tom Stocky, a product manager at Google.

Google expects the search engine will be used primarily as a learning tool to help students and serious programmers, rather than a way to find and copy another person's code.

Stocky said: "Most of the code is open source so you can reuse it. But I don't think that's the primary use - it's more about how to learn about things and, when you're building open source packages, to make sure you doing it the right way."

For example, a developer may need to write a function as part of an application and search the web to see other examples.

Google engineers, many of whom participate in open source projects, already use these code searching capabilities internally. Since it is a Google Labs project, the company is not yet seeking to monetise searches through ads, Stocky said.

The search engine will allow people to do both keyword search and "regular expressions", which allow people to search a specified pattern, he said. For example, a person could narrow search to JavaScript functions, which will help find more examples, Stocky said.

As it does with many of its services, Google will release an application programming interface (API) to create an XML feed based on a specific query.

Although it doesn't sell programming tools, Google has an active developer outreach programme and relies on third-party programmers to enhance its services.

For example, developers have created popular mash-up applications that display information from one website using its Google Maps service.

Stocky said: "More and more [the developer community] is the way Google products are getting to scale. We think developers can really improve Google products and use Google technology to improve their own products."

Martin LaMonica writes for CNET News.com