README.md

Piranha Swift

Piranha scans source files to delete code related to stale feature flags leading to a cleaner, safer, more performant, and more maintainable code base.

Development

• Run swift build && swift package generate-xcodeproj
• Open Xcode project
• Make required changes and do local testing
• Run sh package.sh
• Run sh test.sh (should print a successful message without a diff)

Usage

Piranha Swift can be configured to recognize different flag APIs and flag behaviours by specifying a properties.json file and the appropriate command line options.

USAGE: <piranha_exe> cleanup-stale-flags [--source-file <source-file>] [--config-file <config-file>] --flag <flag> [--group-name <group-name>] [--treated]

OPTIONS:
  -s, --source-file <source-file>
                          Input source file for Piranha
  -c, --config-file <config-file>
                          Path of configuration file for Piranha 
  -f, --flag <flag>       Name of the stale flag 
  --group-name <group-name>
  -t, --treated           If this option is supplied, the flag is treated, otherwise it is control. 
  -h, --help              Show help information.

Example

Consider the following properties file properties.json.

{
  "methodProperties": [
    {
      "methodName": "isToggleDisabled",
      "flagType": "control",
      "flagIndex": 0
    },
    {
      "methodName": "isFlagTreated",
      "flagType": "treated",
      "flagIndex": 0
    },
    {
      "methodName": "isToggleEnabled",
      "flagType": "treated",
      "flagIndex": 0
    }
  ]
}

This specifies a list of flag APIs each of which return a boolean value. It is assumed that a method returns true iff the flagType specified in the properties file matches the flag behaviour specified at runtime. For example, if the flag behavior is treated, isFlagTreated(flag) will return true and isToggleDisabled(flag) will return false.

The following code in Examples/sample.swift contains the stale flag featureFlag

// Simple flag cleanup in conditional
if cachedExperiments.isTreated(forExperiment: ExperimentNamesSwift.featureFlag) {
    f1();
 } else {
    f2();
 }

// Assignment cleanup
var a = isToggleDisabled(ExperimentNamesSwift.featureFlag)
if(a) {
   f1()
} else {
   f2()
}

When this file is run through Piranha with the command

<piranha_exe> cleanup-stale-flags -c properties.json -s Examples/sample.swift -f featureFlag --treated

It yields the following output:

f1()
f2()

Note that code-style and comments are preserved wherever possible by default.