Commit Graph

8 Commits

Author SHA1 Message Date
Stefan Holderbach
95b78eee25
Change the usage misnomer to "description" (#13598)
# Description
    
The meaning of the word usage is specific to describing how a command
function is *used* and not a synonym for general description. Usage can
be used to describe the SYNOPSIS or EXAMPLES sections of a man page
where the permitted argument combinations are shown or example *uses*
are given.
Let's not confuse people and call it what it is a description.

Our `help` command already creates its own *Usage* section based on the
available arguments and doesn't refer to the description with usage.

# User-Facing Changes

`help commands` and `scope commands` will now use `description` or
`extra_description`
`usage`-> `description`
`extra_usage` -> `extra_description`

Breaking change in the plugin protocol:

In the signature record communicated with the engine.
`usage`-> `description`
`extra_usage` -> `extra_description`

The same rename also takes place for the methods on
`SimplePluginCommand` and `PluginCommand`

# Tests + Formatting
- Updated plugin protocol specific changes
# After Submitting
- [ ] update plugin protocol doc
2024-08-22 12:02:08 +02:00
Stefan Holderbach
076a29ae19
Document public types in nu-protocol (#12906)
- **Doc-comment public `nu-protocol` modules**
- **Doccomment argument/signature/call stuff**
- **Doccomment cell path types**
- **Doccomment expression stuff**
- **Doccomment import patterns**
- **Doccomment pattern matching AST nodes**
2024-07-11 13:30:12 +02:00
Devyn Cairns
d7392f1f3b
Internal representation (IR) compiler and evaluator (#13330)
# Description

This PR adds an internal representation language to Nushell, offering an
alternative evaluator based on simple instructions, stream-containing
registers, and indexed control flow. The number of registers required is
determined statically at compile-time, and the fixed size required is
allocated upon entering the block.

Each instruction is associated with a span, which makes going backwards
from IR instructions to source code very easy.

Motivations for IR:

1. **Performance.** By simplifying the evaluation path and making it
more cache-friendly and branch predictor-friendly, code that does a lot
of computation in Nushell itself can be sped up a decent bit. Because
the IR is fairly easy to reason about, we can also implement
optimization passes in the future to eliminate and simplify code.
2. **Correctness.** The instructions mostly have very simple and
easily-specified behavior, so hopefully engine changes are a little bit
easier to reason about, and they can be specified in a more formal way
at some point. I have made an effort to document each of the
instructions in the docs for the enum itself in a reasonably specific
way. Some of the errors that would have happened during evaluation
before are now moved to the compilation step instead, because they don't
make sense to check during evaluation.
3. **As an intermediate target.** This is a good step for us to bring
the [`new-nu-parser`](https://github.com/nushell/new-nu-parser) in at
some point, as code generated from new AST can be directly compared to
code generated from old AST. If the IR code is functionally equivalent,
it will behave the exact same way.
4. **Debugging.** With a little bit more work, we can probably give
control over advancing the virtual machine that `IrBlock`s run on to
some sort of external driver, making things like breakpoints and single
stepping possible. Tools like `view ir` and [`explore
ir`](https://github.com/devyn/nu_plugin_explore_ir) make it easier than
before to see what exactly is going on with your Nushell code.

The goal is to eventually replace the AST evaluator entirely, once we're
sure it's working just as well. You can help dogfood this by running
Nushell with `$env.NU_USE_IR` set to some value. The environment
variable is checked when Nushell starts, so config runs with IR, or it
can also be set on a line at the REPL to change it dynamically. It is
also checked when running `do` in case within a script you want to just
run a specific piece of code with or without IR.

# Example

```nushell
view ir { |data|
  mut sum = 0
  for n in $data {
    $sum += $n
  }
  $sum
}
```
  
```gas
# 3 registers, 19 instructions, 0 bytes of data
   0: load-literal           %0, int(0)
   1: store-variable         var 904, %0 # let
   2: drain                  %0
   3: drop                   %0
   4: load-variable          %1, var 903
   5: iterate                %0, %1, end 15 # for, label(1), from(14:)
   6: store-variable         var 905, %0
   7: load-variable          %0, var 904
   8: load-variable          %2, var 905
   9: binary-op              %0, Math(Plus), %2
  10: span                   %0
  11: store-variable         var 904, %0
  12: load-literal           %0, nothing
  13: drain                  %0
  14: jump                   5
  15: drop                   %0          # label(0), from(5:)
  16: drain                  %0
  17: load-variable          %0, var 904
  18: return                 %0
```

# Benchmarks

All benchmarks run on a base model Mac Mini M1.

## Iterative Fibonacci sequence

This is about as best case as possible, making use of the much faster
control flow. Most code will not experience a speed improvement nearly
this large.

```nushell
def fib [n: int] {
  mut a = 0
  mut b = 1
  for _ in 2..=$n {
    let c = $a + $b
    $a = $b
    $b = $c
  }
  $b
}
use std bench
bench { 0..50 | each { |n| fib $n } }
```

IR disabled:

```
╭───────┬─────────────────╮
│ mean  │ 1ms 924µs 665ns │
│ min   │ 1ms 700µs 83ns  │
│ max   │ 3ms 450µs 125ns │
│ std   │ 395µs 759ns     │
│ times │ [list 50 items] │
╰───────┴─────────────────╯
```

IR enabled:

```
╭───────┬─────────────────╮
│ mean  │ 452µs 820ns     │
│ min   │ 427µs 417ns     │
│ max   │ 540µs 167ns     │
│ std   │ 17µs 158ns      │
│ times │ [list 50 items] │
╰───────┴─────────────────╯
```

![explore ir
view](https://github.com/nushell/nushell/assets/10729/d7bccc03-5222-461c-9200-0dce71b83b83)

##
[gradient_benchmark_no_check.nu](https://github.com/nushell/nu_scripts/blob/main/benchmarks/gradient_benchmark_no_check.nu)

IR disabled:

```
╭───┬──────────────────╮
│ 0 │ 27ms 929µs 958ns │
│ 1 │ 21ms 153µs 459ns │
│ 2 │ 18ms 639µs 666ns │
│ 3 │ 19ms 554µs 583ns │
│ 4 │ 13ms 383µs 375ns │
│ 5 │ 11ms 328µs 208ns │
│ 6 │  5ms 659µs 542ns │
╰───┴──────────────────╯
```

IR enabled:

```
╭───┬──────────────────╮
│ 0 │       22ms 662µs │
│ 1 │ 17ms 221µs 792ns │
│ 2 │ 14ms 786µs 708ns │
│ 3 │ 13ms 876µs 834ns │
│ 4 │  13ms 52µs 875ns │
│ 5 │ 11ms 269µs 666ns │
│ 6 │  6ms 942µs 500ns │
╰───┴──────────────────╯
```

##
[random-bytes.nu](https://github.com/nushell/nu_scripts/blob/main/benchmarks/random-bytes.nu)

I got pretty random results out of this benchmark so I decided not to
include it. Not clear why.

# User-Facing Changes
- IR compilation errors may appear even if the user isn't evaluating
with IR.
- IR evaluation can be enabled by setting the `NU_USE_IR` environment
variable to any value.
- New command `view ir` pretty-prints the IR for a block, and `view ir
--json` can be piped into an external tool like [`explore
ir`](https://github.com/devyn/nu_plugin_explore_ir).

# Tests + Formatting
All tests are passing with `NU_USE_IR=1`, and I've added some more eval
tests to compare the results for some very core operations. I will
probably want to add some more so we don't have to always check
`NU_USE_IR=1 toolkit test --workspace` on a regular basis.

# After Submitting
- [ ] release notes
- [ ] further documentation of instructions?
- [ ] post-release: publish `nu_plugin_explore_ir`
2024-07-10 17:33:59 -07:00
Ian Manske
cc9f41e553
Use CommandType in more places (#12832)
# Description
Kind of a vague title, but this PR does two main things:
1. Rather than overriding functions like `Command::is_parser_keyword`,
this PR instead changes commands to override `Command::command_type`.
The `CommandType` returned by `Command::command_type` is then used to
automatically determine whether `Command::is_parser_keyword` and the
other `is_{type}` functions should return true. These changes allow us
to remove the `CommandType::Other` case and should also guarantee than
only one of the `is_{type}` functions on `Command` will return true.
2. Uses the new, reworked `Command::command_type` function in the `scope
commands` and `which` commands.


# User-Facing Changes
- Breaking change for `scope commands`: multiple columns (`is_builtin`,
`is_keyword`, `is_plugin`, etc.) have been merged into the `type`
column.
- Breaking change: the `which` command can now report `plugin` or
`keyword` instead of `built-in` in the `type` column. It may also now
report `external` instead of `custom` in the `type` column for known
`extern`s.
2024-05-18 23:37:31 +00:00
Ian Manske
b6c7656194
IO and redirection overhaul (#11934)
# Description
The PR overhauls how IO redirection is handled, allowing more explicit
and fine-grain control over `stdout` and `stderr` output as well as more
efficient IO and piping.

To summarize the changes in this PR:
- Added a new `IoStream` type to indicate the intended destination for a
pipeline element's `stdout` and `stderr`.
- The `stdout` and `stderr` `IoStream`s are stored in the `Stack` and to
avoid adding 6 additional arguments to every eval function and
`Command::run`. The `stdout` and `stderr` streams can be temporarily
overwritten through functions on `Stack` and these functions will return
a guard that restores the original `stdout` and `stderr` when dropped.
- In the AST, redirections are now directly part of a `PipelineElement`
as a `Option<Redirection>` field instead of having multiple different
`PipelineElement` enum variants for each kind of redirection. This
required changes to the parser, mainly in `lite_parser.rs`.
- `Command`s can also set a `IoStream` override/redirection which will
apply to the previous command in the pipeline. This is used, for
example, in `ignore` to allow the previous external command to have its
stdout redirected to `Stdio::null()` at spawn time. In contrast, the
current implementation has to create an os pipe and manually consume the
output on nushell's side. File and pipe redirections (`o>`, `e>`, `e>|`,
etc.) have precedence over overrides from commands.

This PR improves piping and IO speed, partially addressing #10763. Using
the `throughput` command from that issue, this PR gives the following
speedup on my setup for the commands below:
| Command | Before (MB/s) | After (MB/s) | Bash (MB/s) |
| --------------------------- | -------------:| ------------:|
-----------:|
| `throughput o> /dev/null` | 1169 | 52938 | 54305 |
| `throughput \| ignore` | 840 | 55438 | N/A |
| `throughput \| null` | Error | 53617 | N/A |
| `throughput \| rg 'x'` | 1165 | 3049 | 3736 |
| `(throughput) \| rg 'x'` | 810 | 3085 | 3815 |

(Numbers above are the median samples for throughput)

This PR also paves the way to refactor our `ExternalStream` handling in
the various commands. For example, this PR already fixes the following
code:
```nushell
^sh -c 'echo -n "hello "; sleep 0; echo "world"' | find "hello world"
```
This returns an empty list on 0.90.1 and returns a highlighted "hello
world" on this PR.

Since the `stdout` and `stderr` `IoStream`s are available to commands
when they are run, then this unlocks the potential for more convenient
behavior. E.g., the `find` command can disable its ansi highlighting if
it detects that the output `IoStream` is not the terminal. Knowing the
output streams will also allow background job output to be redirected
more easily and efficiently.

# User-Facing Changes
- External commands returned from closures will be collected (in most
cases):
  ```nushell
  1..2 | each {|_| nu -c "print a" }
  ```
This gives `["a", "a"]` on this PR, whereas this used to print "a\na\n"
and then return an empty list.

  ```nushell
  1..2 | each {|_| nu -c "print -e a" }
  ```
This gives `["", ""]` and prints "a\na\n" to stderr, whereas this used
to return an empty list and print "a\na\n" to stderr.

- Trailing new lines are always trimmed for external commands when
piping into internal commands or collecting it as a value. (Failure to
decode the output as utf-8 will keep the trailing newline for the last
binary value.) In the current nushell version, the following three code
snippets differ only in parenthesis placement, but they all also have
different outputs:

  1. `1..2 | each { ^echo a }`
     ```
     a
     a
     ╭────────────╮
     │ empty list │
     ╰────────────╯
     ```
  2. `1..2 | each { (^echo a) }`
     ```
     ╭───┬───╮
     │ 0 │ a │
     │ 1 │ a │
     ╰───┴───╯
     ```
  3. `1..2 | (each { ^echo a })`
     ```
     ╭───┬───╮
     │ 0 │ a │
     │   │   │
     │ 1 │ a │
     │   │   │
     ╰───┴───╯
     ```

  But in this PR, the above snippets will all have the same output:
  ```
  ╭───┬───╮
  │ 0 │ a │
  │ 1 │ a │
  ╰───┴───╯
  ```

- All existing flags on `run-external` are now deprecated.

- File redirections now apply to all commands inside a code block:
  ```nushell
  (nu -c "print -e a"; nu -c "print -e b") e> test.out
  ```
This gives "a\nb\n" in `test.out` and prints nothing. The same result
would happen when printing to stdout and using a `o>` file redirection.

- External command output will (almost) never be ignored, and ignoring
output must be explicit now:
  ```nushell
  (^echo a; ^echo b)
  ```
This prints "a\nb\n", whereas this used to print only "b\n". This only
applies to external commands; values and internal commands not in return
position will not print anything (e.g., `(echo a; echo b)` still only
prints "b").

- `complete` now always captures stderr (`do` is not necessary).

# After Submitting
The language guide and other documentation will need to be updated.
2024-03-14 15:51:55 -05:00
Jakub Žádník
e88a51e930
Refactor scope commands (#10023) 2023-08-17 11:58:38 +03:00
Stefan Holderbach
62575c9a4f
Document and critically review ShellError variants - Ep. 3 (#8340)
Continuation of #8229 and #8326

# Description

The `ShellError` enum at the moment is kind of messy. 

Many variants are basic tuple structs where you always have to reference
the implementation with its macro invocation to know which field serves
which purpose.
Furthermore we have both variants that are kind of redundant or either
overly broad to be useful for the user to match on or overly specific
with few uses.

So I set out to start fixing the lacking documentation and naming to
make it feasible to critically review the individual usages and fix
those.
Furthermore we can decide to join or split up variants that don't seem
to be fit for purpose.

# Call to action

**Everyone:** Feel free to add review comments if you spot inconsistent
use of `ShellError` variants.

# User-Facing Changes

(None now, end goal more explicit and consistent error messages)

# Tests + Formatting

(No additional tests needed so far)

# Commits (so far)

- Remove `ShellError::FeatureNotEnabled`
- Name fields on `SE::ExternalNotSupported`
- Name field on `SE::InvalidProbability`
- Name fields on `SE::NushellFailed` variants
- Remove unused `SE::NushellFailedSpannedHelp`
- Name field on `SE::VariableNotFoundAtRuntime`
- Name fields on `SE::EnvVarNotFoundAtRuntime`
- Name fields on `SE::ModuleNotFoundAtRuntime`
- Remove usused `ModuleOrOverlayNotFoundAtRuntime`
- Name fields on `SE::OverlayNotFoundAtRuntime`
- Name field on `SE::NotFound`
2023-03-06 18:33:09 +01:00
Jakub Žádník
a3f817d71b
Re-implement aliases (#8123)
# Description

This PR adds an alternative alias implementation. Old aliases still work
but you need to use `old-alias` instead of `alias`.

Instead of replacing spans in the original code and re-parsing, which
proved to be extremely error-prone and a constant source of panics, the
new implementation creates a new command that references the old
command. Consider the new alias defined as `alias ll = ls -l`. The
parser creates a new command called `ll` and remembers that it is
actually a `ls` command called with the `-l` flag. Then, when the parser
sees the `ll` command, it will translate it to `ls -l` and passes to it
any parameters that were passed to the call to `ll`. It works quite
similar to how known externals defined with `extern` are implemented.

The new alias implementation should work the same way as the old
aliases, including exporting from modules, referencing both known and
unknown externals. It seems to preserve custom completions and pipeline
metadata. It is quite robust in most cases but there are some rough
edges (see later).

Fixes https://github.com/nushell/nushell/issues/7648,
https://github.com/nushell/nushell/issues/8026,
https://github.com/nushell/nushell/issues/7512,
https://github.com/nushell/nushell/issues/5780,
https://github.com/nushell/nushell/issues/7754

No effect: https://github.com/nushell/nushell/issues/8122 (we might
revisit the completions code after this PR)

Should use custom command instead:
https://github.com/nushell/nushell/issues/6048

# User-Facing Changes

Since aliases are now basically commands, it has some new implications:

1. `alias spam = "spam"` (requires command call)
	* **workaround**: use `alias spam = echo "spam"`
2. `def foo [] { 'foo' }; alias foo = ls -l` (foo defined more than
once)
* **workaround**: use different name (commands also have this
limitation)
4. `alias ls = (ls | sort-by type name -i)`
* **workaround**: Use custom command. _The common issue with this is
that it is currently not easy to pass flags through custom commands and
command referencing itself will lead to stack overflow. Both of these
issues are meant to be addressed._
5. TODO: Help messages, `which` command, `$nu.scope.aliases`, etc.
* Should we treat the aliases as commands or should they be separated
from regular commands?
6. Needs better error message and syntax highlight for recursed alias
(`alias f = f`)
7. Can't create alias with the same name as existing command (`alias ls
= ls -a`)
	* Might be possible to add support for it (not 100% sure)
8. Standalone `alias` doesn't list aliases anymore
9. Can't alias parser keywords (e.g., stuff like `alias ou = overlay
use` won't work)
	* TODO: Needs a better error message when attempting to do so

# Tests + Formatting

Don't forget to add tests that cover your changes.

Make sure you've run and fixed any issues with these commands:

- `cargo fmt --all -- --check` to check standard code formatting (`cargo
fmt --all` applies these changes)
- `cargo clippy --workspace -- -D warnings -D clippy::unwrap_used -A
clippy::needless_collect` to check that you're using the standard code
style
- `cargo test --workspace` to check that all tests pass

# After Submitting

If your PR had any user-facing changes, update [the
documentation](https://github.com/nushell/nushell.github.io) after the
PR is merged, if necessary. This will help us keep the docs up to date.
2023-02-27 20:44:05 +13:00