Added support for running benchmarks using substring filters. Positional arguments prefixed with a single + or - sign are interpreted as benchmark name filters.
Excecutes all benchmarks whose names include any of the strings prefixed with a plus sign but none of the strings prefixed with a minus sign.
The `--help` option now prints standard usage description with documentaion for all arguments:
````
$ Benchmark_O --help
usage: Benchmark_O [--argument=VALUE] [TEST [TEST ...]]
positional arguments:
TEST name or number of the benchmark to measure
optional arguments:
--help show this help message and exit
--num-samples number of samples to take per benchmark; default: 1
--num-iters number of iterations averaged in the sample;
default: auto-scaled to measure for 1 second
--iter-scale number of seconds used for num-iters calculation
default: 1
--verbose increase output verbosity
--delim value delimiter used for log output; default: ,
--tags run tests matching all the specified categories
--skip-tags don't run tests matching any of the specified
categories; default: unstable,skip
--sleep number of seconds to sleep after benchmarking
--list don't run the tests, just log the list of test
numbers, names and tags (respects specified filters)
````
The `parseArgs` funtion is now a private method on `ArgumentParser`.
Removed `Arguments` struct and moved the `Argument` as a nested struct into the parser.
Adjusted error messages and the corresponding checks.
In case of invalid command line arguments, there is no reasonable recovery, the `ArgumentParser` can exit the program itself. It is therefore no longer necessary to propagate the `ArgumentError`s outside of the parser.
The `ArgumentParser` now has a configuration phase which specifies the supported arguments and their handling. The configured parser is then executed using the `parse` method which returns the parsed result.
Refactored to use Swift’s idiomatic error handling.
In case of invalid argument errors, the message is printed to `stderr` and we exit gracefully with error code 1. We no longer crash the app in most cases.
This allows the benchmarks to be built without the Foundation overlay being
built. I am currently prototyping having +0 parameters for all normal arguments
and have not gotten the Foundation overlay to work yet... so this commit will
let me get some initial numbers for the subset of the tests that do not depend
on Foundation.
rdar://34222540
