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Make plugins able to find and call other commands (#13407)

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# Description

Adds functionality to the plugin interface to support calling internal
commands from plugins. For example, using `view ir --json`:

```rust
let closure: Value = call.req(0)?;

let Some(decl_id) = engine.find_decl("view ir")? else {
    return Err(LabeledError::new("`view ir` not found"));
};

let ir_json = engine.call_decl(
    decl_id,
    EvaluatedCall::new(call.head)
        .with_named("json".into_spanned(call.head), Value::bool(true, call.head))
        .with_positional(closure),
    PipelineData::Empty,
    true,
    false,
)?.into_value()?.into_string()?;

let ir = serde_json::from_value(&ir_json);

// ...
```

# User-Facing Changes

Plugin developers can now use `EngineInterface::find_decl()` and
`call_decl()` to call internal commands, which could be handy for
formatters like `to csv` or `to nuon`, or for reflection commands that
help gain insight into the engine.

# Tests + Formatting
- 🟢 `toolkit fmt`
- 🟢 `toolkit clippy`
- 🟢 `toolkit test`
- 🟢 `toolkit test stdlib`

# After Submitting
- [ ] release notes
- [ ] update plugin protocol documentation: `FindDecl`, `CallDecl`
engine calls; `Identifier` engine call response
This commit is contained in:
Devyn Cairns 2024-07-18 22:54:21 -07:00 committed by GitHub
parent c19944f291
commit f3843a6176
No known key found for this signature in database
GPG Key ID: B5690EEEBB952194
11 changed files with 418 additions and 21 deletions
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103
crates/nu-plugin-engine/src/context.rs
View File

@ -1,9 +1,10 @@
use crate::util::MutableCow;
use nu_engine::{get_eval_block_with_early_return, get_full_help, ClosureEvalOnce};
use nu_plugin_protocol::EvaluatedCall;
use nu_protocol::{
engine::{Call, Closure, EngineState, Redirection, Stack},
Config, IntoSpanned, OutDest, PipelineData, PluginIdentity, ShellError, Signals, Span, Spanned,
Value,
ir, Config, DeclId, IntoSpanned, OutDest, PipelineData, PluginIdentity, ShellError, Signals,
Span, Spanned, Value,
};
use std::{
borrow::Cow,
@ -44,6 +45,17 @@ pub trait PluginExecutionContext: Send + Sync {
redirect_stdout: bool,
redirect_stderr: bool,
) -> Result<PipelineData, ShellError>;
/// Find a declaration by name
fn find_decl(&self, name: &str) -> Result<Option<DeclId>, ShellError>;
/// Call a declaration with arguments and input
fn call_decl(
&mut self,
decl_id: DeclId,
call: EvaluatedCall,
input: PipelineData,
redirect_stdout: bool,
redirect_stderr: bool,
) -> Result<PipelineData, ShellError>;
/// Create an owned version of the context with `'static` lifetime
fn boxed(&self) -> Box<dyn PluginExecutionContext>;
}
@ -177,19 +189,10 @@ impl<'a> PluginExecutionContext for PluginExecutionCommandContext<'a> {
.captures_to_stack(closure.item.captures)
.reset_pipes();
let stdout = if redirect_stdout {
Some(Redirection::Pipe(OutDest::Capture))
} else {
None
};
let stderr = if redirect_stderr {
Some(Redirection::Pipe(OutDest::Capture))
} else {
None
};
let stack = &mut stack.push_redirection(stdout, stderr);
let stack = &mut stack.push_redirection(
redirect_stdout.then_some(Redirection::Pipe(OutDest::Capture)),
redirect_stderr.then_some(Redirection::Pipe(OutDest::Capture)),
);
// Set up the positional arguments
for (idx, value) in positional.into_iter().enumerate() {
@ -211,6 +214,57 @@ impl<'a> PluginExecutionContext for PluginExecutionCommandContext<'a> {
eval_block_with_early_return(&self.engine_state, stack, block, input)
}
fn find_decl(&self, name: &str) -> Result<Option<DeclId>, ShellError> {
Ok(self.engine_state.find_decl(name.as_bytes(), &[]))
}
fn call_decl(
&mut self,
decl_id: DeclId,
call: EvaluatedCall,
input: PipelineData,
redirect_stdout: bool,
redirect_stderr: bool,
) -> Result<PipelineData, ShellError> {
if decl_id >= self.engine_state.num_decls() {
return Err(ShellError::GenericError {
error: "Plugin misbehaving".into(),
msg: format!("Tried to call unknown decl id: {}", decl_id),
span: Some(call.head),
help: None,
inner: vec![],
});
}
let decl = self.engine_state.get_decl(decl_id);
let stack = &mut self.stack.push_redirection(
redirect_stdout.then_some(Redirection::Pipe(OutDest::Capture)),
redirect_stderr.then_some(Redirection::Pipe(OutDest::Capture)),
);
let mut call_builder = ir::Call::build(decl_id, call.head);
for positional in call.positional {
call_builder.add_positional(stack, positional.span(), positional);
}
for (name, value) in call.named {
if let Some(value) = value {
call_builder.add_named(stack, &name.item, "", name.span, value);
} else {
call_builder.add_flag(stack, &name.item, "", name.span);
}
}
decl.run(
&self.engine_state,
stack,
&(&call_builder.finish()).into(),
input,
)
}
fn boxed(&self) -> Box<dyn PluginExecutionContext + 'static> {
Box::new(PluginExecutionCommandContext {
identity: self.identity.clone(),
@ -298,6 +352,25 @@ impl PluginExecutionContext for PluginExecutionBogusContext {
})
}
fn find_decl(&self, _name: &str) -> Result<Option<DeclId>, ShellError> {
Err(ShellError::NushellFailed {
msg: "find_decl not implemented on bogus".into(),
})
}
fn call_decl(
&mut self,
_decl_id: DeclId,
_call: EvaluatedCall,
_input: PipelineData,
_redirect_stdout: bool,
_redirect_stderr: bool,
) -> Result<PipelineData, ShellError> {
Err(ShellError::NushellFailed {
msg: "call_decl not implemented on bogus".into(),
})
}
fn boxed(&self) -> Box<dyn PluginExecutionContext + 'static> {
Box::new(PluginExecutionBogusContext)
}

16
crates/nu-plugin-engine/src/interface/mod.rs
View File

@ -1316,6 +1316,22 @@ pub(crate) fn handle_engine_call(
} => context
.eval_closure(closure, positional, input, redirect_stdout, redirect_stderr)
.map(EngineCallResponse::PipelineData),
EngineCall::FindDecl(name) => context.find_decl(&name).map(|decl_id| {
if let Some(decl_id) = decl_id {
EngineCallResponse::Identifier(decl_id)
} else {
EngineCallResponse::empty()
}
}),
EngineCall::CallDecl {
decl_id,
call,
input,
redirect_stdout,
redirect_stderr,
} => context
.call_decl(decl_id, call, input, redirect_stdout, redirect_stderr)
.map(EngineCallResponse::PipelineData),
}
}

86
crates/nu-plugin-protocol/src/evaluated_call.rs
View File

@ -27,6 +27,82 @@ pub struct EvaluatedCall {
}
impl EvaluatedCall {
/// Create a new [`EvaluatedCall`] with the given head span.
pub fn new(head: Span) -> EvaluatedCall {
EvaluatedCall {
head,
positional: vec![],
named: vec![],
}
}
/// Add a positional argument to an [`EvaluatedCall`].
///
/// # Example
///
/// ```rust
/// # use nu_protocol::{Value, Span, IntoSpanned};
/// # use nu_plugin_protocol::EvaluatedCall;
/// # let head = Span::test_data();
/// let mut call = EvaluatedCall::new(head);
/// call.add_positional(Value::test_int(1337));
/// ```
pub fn add_positional(&mut self, value: Value) -> &mut Self {
self.positional.push(value);
self
}
/// Add a named argument to an [`EvaluatedCall`].
///
/// # Example
///
/// ```rust
/// # use nu_protocol::{Value, Span, IntoSpanned};
/// # use nu_plugin_protocol::EvaluatedCall;
/// # let head = Span::test_data();
/// let mut call = EvaluatedCall::new(head);
/// call.add_named("foo".into_spanned(head), Value::test_string("bar"));
/// ```
pub fn add_named(&mut self, name: Spanned<impl Into<String>>, value: Value) -> &mut Self {
self.named.push((name.map(Into::into), Some(value)));
self
}
/// Add a flag argument to an [`EvaluatedCall`]. A flag argument is a named argument with no
/// value.
///
/// # Example
///
/// ```rust
/// # use nu_protocol::{Value, Span, IntoSpanned};
/// # use nu_plugin_protocol::EvaluatedCall;
/// # let head = Span::test_data();
/// let mut call = EvaluatedCall::new(head);
/// call.add_flag("pretty".into_spanned(head));
/// ```
pub fn add_flag(&mut self, name: Spanned<impl Into<String>>) -> &mut Self {
self.named.push((name.map(Into::into), None));
self
}
/// Builder variant of [`.add_positional()`].
pub fn with_positional(mut self, value: Value) -> Self {
self.add_positional(value);
self
}
/// Builder variant of [`.add_named()`].
pub fn with_named(mut self, name: Spanned<impl Into<String>>, value: Value) -> Self {
self.add_named(name, value);
self
}
/// Builder variant of [`.add_flag()`].
pub fn with_flag(mut self, name: Spanned<impl Into<String>>) -> Self {
self.add_flag(name);
self
}
/// Try to create an [`EvaluatedCall`] from a command `Call`.
pub fn try_from_call(
call: &Call,
@ -192,6 +268,16 @@ impl EvaluatedCall {
Ok(false)
}
/// Returns the [`Span`] of the name of an optional named argument.
///
/// This can be used in errors for named arguments that don't take values.
pub fn get_flag_span(&self, flag_name: &str) -> Option<Span> {
self.named
.iter()
.find(|(name, _)| name.item == flag_name)
.map(|(name, _)| name.span)
}
/// Returns the [`Value`] of an optional named argument
///
/// # Examples

35
crates/nu-plugin-protocol/src/lib.rs
View File

@ -22,7 +22,7 @@ mod tests;
pub mod test_util;
use nu_protocol::{
ast::Operator, engine::Closure, ByteStreamType, Config, LabeledError, PipelineData,
ast::Operator, engine::Closure, ByteStreamType, Config, DeclId, LabeledError, PipelineData,
PluginMetadata, PluginSignature, ShellError, Span, Spanned, Value,
};
use nu_utils::SharedCow;
@ -494,6 +494,21 @@ pub enum EngineCall<D> {
/// Whether to redirect stderr from external commands
redirect_stderr: bool,
},
/// Find a declaration by name
FindDecl(String),
/// Call a declaration with args
CallDecl {
/// The id of the declaration to be called (can be found with `FindDecl`)
decl_id: DeclId,
/// Information about the call (head span, arguments, etc.)
call: EvaluatedCall,
/// Pipeline input to the call
input: D,
/// Whether to redirect stdout from external commands
redirect_stdout: bool,
/// Whether to redirect stderr from external commands
redirect_stderr: bool,
},
}
impl<D> EngineCall<D> {
@ -511,6 +526,8 @@ impl<D> EngineCall<D> {
EngineCall::LeaveForeground => "LeaveForeground",
EngineCall::GetSpanContents(_) => "GetSpanContents",
EngineCall::EvalClosure { .. } => "EvalClosure",
EngineCall::FindDecl(_) => "FindDecl",
EngineCall::CallDecl { .. } => "CallDecl",
}
}
@ -544,6 +561,20 @@ impl<D> EngineCall<D> {
redirect_stdout,
redirect_stderr,
},
EngineCall::FindDecl(name) => EngineCall::FindDecl(name),
EngineCall::CallDecl {
decl_id,
call,
input,
redirect_stdout,
redirect_stderr,
} => EngineCall::CallDecl {
decl_id,
call,
input: f(input)?,
redirect_stdout,
redirect_stderr,
},
})
}
}
@ -556,6 +587,7 @@ pub enum EngineCallResponse<D> {
PipelineData(D),
Config(SharedCow<Config>),
ValueMap(HashMap<String, Value>),
Identifier(usize),
}
impl<D> EngineCallResponse<D> {
@ -570,6 +602,7 @@ impl<D> EngineCallResponse<D> {
EngineCallResponse::PipelineData(data) => EngineCallResponse::PipelineData(f(data)?),
EngineCallResponse::Config(config) => EngineCallResponse::Config(config),
EngineCallResponse::ValueMap(map) => EngineCallResponse::ValueMap(map),
EngineCallResponse::Identifier(id) => EngineCallResponse::Identifier(id),
})
}
}

73
crates/nu-plugin/src/plugin/interface/mod.rs
View File

@ -6,12 +6,12 @@ use nu_plugin_core::{
StreamManagerHandle,
};
use nu_plugin_protocol::{
CallInfo, CustomValueOp, EngineCall, EngineCallId, EngineCallResponse, Ordering, PluginCall,
PluginCallId, PluginCallResponse, PluginCustomValue, PluginInput, PluginOption, PluginOutput,
ProtocolInfo,
CallInfo, CustomValueOp, EngineCall, EngineCallId, EngineCallResponse, EvaluatedCall, Ordering,
PluginCall, PluginCallId, PluginCallResponse, PluginCustomValue, PluginInput, PluginOption,
PluginOutput, ProtocolInfo,
};
use nu_protocol::{
engine::Closure, Config, LabeledError, PipelineData, PluginMetadata, PluginSignature,
engine::Closure, Config, DeclId, LabeledError, PipelineData, PluginMetadata, PluginSignature,
ShellError, Signals, Span, Spanned, Value,
};
use nu_utils::SharedCow;
@ -872,6 +872,71 @@ impl EngineInterface {
}
}
/// Ask the engine for the identifier for a declaration. If found, the result can then be passed
/// to [`.call_decl()`] to call other internal commands.
///
/// See [`.call_decl()`] for an example.
pub fn find_decl(&self, name: impl Into<String>) -> Result<Option<DeclId>, ShellError> {
let call = EngineCall::FindDecl(name.into());
match self.engine_call(call)? {
EngineCallResponse::Error(err) => Err(err),
EngineCallResponse::Identifier(id) => Ok(Some(id)),
EngineCallResponse::PipelineData(PipelineData::Empty) => Ok(None),
_ => Err(ShellError::PluginFailedToDecode {
msg: "Received unexpected response type for EngineCall::FindDecl".into(),
}),
}
}
/// Ask the engine to call an internal command, using the declaration ID previously looked up
/// with [`.find_decl()`].
///
/// # Example
///
/// ```rust,no_run
/// # use nu_protocol::{Value, ShellError, PipelineData};
/// # use nu_plugin::{EngineInterface, EvaluatedCall};
/// # fn example(engine: &EngineInterface, call: &EvaluatedCall) -> Result<Value, ShellError> {
/// if let Some(decl_id) = engine.find_decl("scope commands")? {
/// let commands = engine.call_decl(
/// decl_id,
/// EvaluatedCall::new(call.head),
/// PipelineData::Empty,
/// true,
/// false,
/// )?;
/// commands.into_value(call.head)
/// } else {
/// Ok(Value::list(vec![], call.head))
/// }
/// # }
/// ```
pub fn call_decl(
&self,
decl_id: DeclId,
call: EvaluatedCall,
input: PipelineData,
redirect_stdout: bool,
redirect_stderr: bool,
) -> Result<PipelineData, ShellError> {
let call = EngineCall::CallDecl {
decl_id,
call,
input,
redirect_stdout,
redirect_stderr,
};
match self.engine_call(call)? {
EngineCallResponse::Error(err) => Err(err),
EngineCallResponse::PipelineData(data) => Ok(data),
_ => Err(ShellError::PluginFailedToDecode {
msg: "Received unexpected response type for EngineCall::CallDecl".into(),
}),
}
}
/// Tell the engine whether to disable garbage collection for this plugin.
///
/// The garbage collector is enabled by default, but plugins can turn it off (ideally

2
crates/nu-protocol/src/ir/call.rs
View File

@ -239,7 +239,7 @@ impl CallBuilder {
}
self.inner.args_len += 1;
if let Some(span) = argument.span() {
self.inner.span = self.inner.span.append(span);
self.inner.span = self.inner.span.merge(span);
}
stack.arguments.push(argument);
self

78
crates/nu_plugin_example/src/commands/call_decl.rs Normal file
View File

@ -0,0 +1,78 @@
use nu_plugin::{EngineInterface, EvaluatedCall, PluginCommand};
use nu_protocol::{
IntoSpanned, LabeledError, PipelineData, Record, Signature, Spanned, SyntaxShape, Value,
};
use crate::ExamplePlugin;
pub struct CallDecl;
impl PluginCommand for CallDecl {
type Plugin = ExamplePlugin;
fn name(&self) -> &str {
"example call-decl"
}
fn signature(&self) -> Signature {
Signature::build(self.name())
.required(
"name",
SyntaxShape::String,
"the name of the command to call",
)
.optional(
"named_args",
SyntaxShape::Record(vec![]),
"named arguments to pass to the command",
)
.rest(
"positional_args",
SyntaxShape::Any,
"positional arguments to pass to the command",
)
}
fn usage(&self) -> &str {
"Demonstrates calling other commands from plugins using `call_decl()`."
}
fn extra_usage(&self) -> &str {
"
The arguments will not be typechecked at parse time. This command is for
demonstration only, and should not be used for anything real.
"
.trim()
}
fn run(
&self,
_plugin: &ExamplePlugin,
engine: &EngineInterface,
call: &EvaluatedCall,
input: PipelineData,
) -> Result<PipelineData, LabeledError> {
let name: Spanned<String> = call.req(0)?;
let named_args: Option<Record> = call.opt(1)?;
let positional_args: Vec<Value> = call.rest(2)?;
let decl_id = engine.find_decl(&name.item)?.ok_or_else(|| {
LabeledError::new(format!("Can't find `{}`", name.item))
.with_label("not in scope", name.span)
})?;
let mut new_call = EvaluatedCall::new(call.head);
for (key, val) in named_args.into_iter().flatten() {
new_call.add_named(key.into_spanned(val.span()), val);
}
for val in positional_args {
new_call.add_positional(val);
}
let result = engine.call_decl(decl_id, new_call, input, true, false)?;
Ok(result)
}
}

2
crates/nu_plugin_example/src/commands/mod.rs
View File

@ -13,11 +13,13 @@ pub use three::Three;
pub use two::Two;
// Engine interface demos
mod call_decl;
mod config;
mod disable_gc;
mod env;
mod view_span;
pub use call_decl::CallDecl;
pub use config::Config;
pub use disable_gc::DisableGc;
pub use env::Env;

1
crates/nu_plugin_example/src/lib.rs
View File

@ -27,6 +27,7 @@ impl Plugin for ExamplePlugin {
Box::new(Env),
Box::new(ViewSpan),
Box::new(DisableGc),
Box::new(CallDecl),
// Stream demos
Box::new(CollectBytes),
Box::new(Echo),

42
tests/plugins/call_decl.rs Normal file
View File

@ -0,0 +1,42 @@
use nu_test_support::nu_with_plugins;
#[test]
fn call_to_json() {
let result = nu_with_plugins!(
cwd: ".",
plugin: ("nu_plugin_example"),
r#"
[42] | example call-decl 'to json' {indent: 4}
"#
);
assert!(result.status.success());
// newlines are removed from test output
assert_eq!("[ 42]", result.out);
}
#[test]
fn call_reduce() {
let result = nu_with_plugins!(
cwd: ".",
plugin: ("nu_plugin_example"),
r#"
[1 2 3] | example call-decl 'reduce' {fold: 10} { |it, acc| $it + $acc }
"#
);
assert!(result.status.success());
assert_eq!("16", result.out);
}
#[test]
fn call_scope_variables() {
let result = nu_with_plugins!(
cwd: ".",
plugin: ("nu_plugin_example"),
r#"
let test_var = 10
example call-decl 'scope variables' | where name == '$test_var' | length
"#
);
assert!(result.status.success());
assert_eq!("1", result.out);
}

1
tests/plugins/mod.rs
View File

@ -1,3 +1,4 @@
mod call_decl;
mod config;
mod core_inc;
mod custom_values;