This commit contains two improvements:
- Support for a Range syntax (and a corresponding Range value)
- Work towards a signature syntax
Implementing the Range syntax resulted in cleaning up how operators in
the core syntax works. There are now two kinds of infix operators
- tight operators (`.` and `..`)
- loose operators
Tight operators may not be interspersed (`$it.left..$it.right` is a
syntax error). Loose operators require whitespace on both sides of the
operator, and can be arbitrarily interspersed. Precedence is left to
right in the core syntax.
Note that delimited syntax (like `( ... )` or `[ ... ]`) is a single
token node in the core syntax. A single token node can be parsed from
beginning to end in a context-free manner.
The rule for `.` is `<token node>.<member>`. The rule for `..` is
`<token node>..<token node>`.
Loose operators all have the same syntactic rule: `<token
node><space><loose op><space><token node>`.
The second aspect of this pull request is the beginning of support for a
signature syntax. Before implementing signatures, a necessary
prerequisite is for the core syntax to support multi-line programs.
That work establishes a few things:
- `;` and newlines are handled in the core grammar, and both count as
"separators"
- line comments begin with `#` and continue until the end of the line
In this commit, multi-token productions in the core grammar can use
separators interchangably with spaces. However, I think we will
ultimately want a different rule preventing separators from occurring
before an infix operator, so that the end of a line is always
unambiguous. This would avoid gratuitous differences between modules and
repl usage.
We already effectively have this rule, because otherwise `x<newline> |
y` would be a single pipeline, but of course that wouldn't work.
The original intent of this patch was to remove more unwraps to reduce
panics. I then lost a ton of time to the fact that the playground isn't
in a temp directory (because of permissions issues on Windows).
This commit improves the test facilities to:
- use a tempdir for the playground
- change the playground API so you instantiate it with a block that
encloses the lifetime of the tempdir
- the block is called with a `dirs` argument that has `dirs.test()` and
other important directories that we were computing by hand all the time
- the block is also called with a `playground` argument that you can use
to construct files (it's the same `Playground` as before)
- change the nu! and nu_error! macros to produce output instead of
taking a variable binding
- change the nu! and nu_error! macros to do the cwd() transformation
internally
- change the nu! and nu_error! macros to take varargs at the end that
get interpolated into the running command
I didn't manage to finish porting all of the tests, so a bunch of tests
are currently commented out. That will need to change before we land
this patch.
This commit makes it possible to force nu to treat a command as an external command by prefixing it with `^`. For example `^dir` will force `dir` to run an external command, even if `dir` is also a registered nu command.
This ensures that users don't need to leave nu just because we happened to use a command they need.
This commit adds a new token type for external commands, which, among other things, makes it pretty straight forward to syntax highlight external commands uniquely, and generally to treat them as special.
