1. A computer-implemented method, the method comprising: maintaining, using one or more processors, an index that indexes source code files, the index including, for each source code file, a respective popularity score, a file name of the source code file, and data describing one or more tags associated with the source code file, wherein the data describing each tag comprises a tag name, a tag definition, a description of the source code file, and one or more code lines associated with the tag; determining the respective popularity score stored in the index for each source code file based on a quantity of references to each source code file in source code of other source code files included in the index; receiving a search query that includes a source code tag and data specifying a programming language; identifying, using the index, search results that satisfy the search query, each search result referencing a respective source code file; ranking the identified search results based on respective popularity scores of the referenced source code files, wherein search results that reference source code files that are not associated with the specified programming language are ranked lower than other search results; and providing the ranked search results in response to the search query.
1. A computer-implemented method, the method comprising: maintaining, using one or more processors, an index that indexes source code files, the index including, for each source code file, a respective popularity score, a file name of the source code file, and data describing one or more tags associated with the source code file, wherein the data describing each tag comprises a tag name, a tag definition, a description of the source code file, and one or more code lines associated with the tag; determining the respective popularity score stored in the index for each source code file based on a quantity of references to each source code file in source code of other source code files included in the index; receiving a search query that includes a source code tag and data specifying a programming language; identifying, using the index, search results that satisfy the search query, each search result referencing a respective source code file; ranking the identified search results based on respective popularity scores of the referenced source code files, wherein search results that reference source code files that are not associated with the specified programming language are ranked lower than other search results; and providing the ranked search results in response to the search query. 2. The method of claim 1 , wherein a reference to a particular source code file in source code of a second source code file is one of an import statement or an include statement in the source code of the second source code file.