Add a `set SETTING := VALUE` construct.
This construct is intended to be extended as needed with new settings,
but for now we're starting with `set shell := [COMMAND, ARG1, ...]`,
which allows setting the shell to use for recipe and backtick execution
in a justfile.
One of the primary reasons for adding this feature is to have a better
story on windows, where users are forced to scrounge up an `sh` binary
if they want to use `just`. This should allow them to use cmd.exe or
powershell in their justfiles, making just optionally dependency-free.
This diff makes positional argument parsing much cleaner, along with
adding a bunch of tests. Just's positional argument parsing is rather,
complex, so hopefully this reform allows it to both be correct and stay
correct.
User-visible changes:
- `just ..` is now accepted, with the same effect as `just ../`
- `just .` is also accepted, with the same effect as `just`
- It is now an error to pass arguments or overrides to subcommands
that do not accept them, namely `--dump`, `--edit`, `--list`,
`--show`, and `--summary`. It is also an error to pass arguments to
`--evaluate`, although `--evaluate` does of course still accept
overrides.
(This is a breaking change, but hopefully worth it, as it will allow us
to add arguments to subcommands which did not previously take
them, if we so desire.)
- Subcommands which do not accept arguments may now accept a
single search-directory argument, so `just --list ../` and
`just --dump foo/` are now accepted, with the former starting the
search for the justfile to list in the parent directory, and the latter
starting the search for the justfile to dump in `foo`.
Just's first parser performed both parsing, i.e the transformation of a
token stream according to the language grammar, and a number of consistency
checks and analysis passes.
This made parsing and analysis quite complex, so this diff introduces a
new, much cleaner `Parser`, and moves existing analysis into a dedicated
`Analyzer`.
- Refactor the lexer tests to be more readable, abandoning the
previous string-based summary DSL in favor of a more obvious
sequence of `TokenKinds` with optional lexemes. The new tests
also test that token lexemes are correct.
- Move duplicated `unindent` function into a shared crate,
`test-utilities`. This new versionless dev-dependency will
prevent publishing to crates.io, at least until rust-lang/cargo/pull/7333
makes it into stable. If we publish a new version before then,
test-utilities will need to be published to crates.io, so we can depend
on it by version.
Eventually, there will probably be a `crate` visibility specifier that
does the same thing as `pub(crate)`. This commit replaces `pub` with
`pub(crate)`, so when `crate` is available we can easily switch to it.
`env_var(key)` looks up the value of the environment variable with name `key`, aborting execution if it is not found.
`env_var_or_default(key, default)` looks up the value of the environment variable with name `key`, returning `default` if it is not found.
