parser_wrapper

Swift CLI that given a directory of Swift source code files attempts to parse each file using swift-ast by yanagiba and then computes several metrics related to error handling. The computed metrics are then written to a .csv file. Each run of parser_wrapper generates one row for the output .csv file. This CLI has been used as part of the paper 'How do Swift developers handle errors'.

To re-run the experiments, and execute the full pipeline, see the following Gist. In the Gist the steps needed to run this tool and all other scripts used to gather the final results are described in detail.

parser_wrapper itself takes three arguments:

• Key: The key of the line that should be appended to the csv file.

• BaseDir: Directory which is the starting point for recursively finding Swift source files. ALl files that end in .swift are parsed using parser_wrapper and the error handling in these files is recorded. After all swift files in the directory have been parsed all results are written to OutFile.

• OutFile: The .csv to which results should be appended after parsing all Swift files in a directory tree. Note that before calling parser_wrapper this file should exist on the file system with a header. The following csv header should be used:

  key, parsedFiles, parserFailed, parserFailedNoEh, compilerFailed, errorTypesEnum, errorTypesClass, errorTypesStruct, throwStatements, try, tryOpt, tryForce, doStatements, throwMethods, rethrows, catch, catchEnum, catchAll, emptyCatch, emptyCatchEnum, emptyCatchAll, catchPerDoMedian, catchPerDoAverage, slocPerCatchMedian, slocPerCatchAverage, slocPerCatchEnumMedian, slocPerCatchEnumAverage, slocPerCatchAllMedian, slocPerCatchAllAverage

  What each of the collected metrics means and why these metrics have been chosen is described in the paper.

Build instructions

Building parser_wrapper includes downloading all dependencies such that parser_wrapper can be linked against the dependencies. This is handled by the Swift build system itself. Building parser_wrapper can be done by opening a terminal in the root folder of the repository and running swift build. Build artifacts can be found in the .debug folder.

Package.swift is the file which contains the information needed by the build system of Swift. Currently the dependency on swift-ast points to a fork of the original swift-ast repository by yanagiba. This to prevent any breaking API changes from influencing parser_wrapper. It should always be possible to point back to the original version of swift-ast in case bugs in the original repository are fixed.