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c747ec75c9
# Description
When implementing a `Command`, one must also import all the types
present in the function signatures for `Command`. This makes it so that
we often import the same set of types in each command implementation
file. E.g., something like this:
```rust
use nu_protocol::ast::Call;
use nu_protocol::engine::{Command, EngineState, Stack};
use nu_protocol::{
record, Category, Example, IntoInterruptiblePipelineData, IntoPipelineData, PipelineData,
ShellError, Signature, Span, Type, Value,
};
```
This PR adds the `nu_engine::command_prelude` module which contains the
necessary and commonly used types to implement a `Command`:
```rust
// command_prelude.rs
pub use crate::CallExt;
pub use nu_protocol::{
ast::{Call, CellPath},
engine::{Command, EngineState, Stack},
record, Category, Example, IntoInterruptiblePipelineData, IntoPipelineData, IntoSpanned,
PipelineData, Record, ShellError, Signature, Span, Spanned, SyntaxShape, Type, Value,
};
```
This should reduce the boilerplate needed to implement a command and
also gives us a place to track the breadth of the `Command` API. I tried
to be conservative with what went into the prelude modules, since it
might be hard/annoying to remove items from the prelude in the future.
Let me know if something should be included or excluded.
67 lines
2.1 KiB
Rust
67 lines
2.1 KiB
Rust
use nu_engine::command_prelude::*;
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#[derive(Clone)]
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pub struct Module;
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impl Command for Module {
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fn name(&self) -> &str {
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"module"
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}
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fn usage(&self) -> &str {
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"Define a custom module."
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}
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fn signature(&self) -> nu_protocol::Signature {
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Signature::build("module")
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.input_output_types(vec![(Type::Nothing, Type::Nothing)])
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.allow_variants_without_examples(true)
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.required("module", SyntaxShape::String, "Module name or module path.")
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.optional(
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"block",
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SyntaxShape::Block,
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"Body of the module if 'module' parameter is not a module path.",
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)
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.category(Category::Core)
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}
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fn extra_usage(&self) -> &str {
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r#"This command is a parser keyword. For details, check:
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https://www.nushell.sh/book/thinking_in_nu.html"#
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}
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fn is_parser_keyword(&self) -> bool {
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true
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}
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fn run(
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&self,
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_engine_state: &EngineState,
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_stack: &mut Stack,
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_call: &Call,
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_input: PipelineData,
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) -> Result<PipelineData, ShellError> {
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Ok(PipelineData::empty())
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}
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fn examples(&self) -> Vec<Example> {
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vec![
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Example {
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description: "Define a custom command in a module and call it",
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example: r#"module spam { export def foo [] { "foo" } }; use spam foo; foo"#,
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result: Some(Value::test_string("foo")),
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},
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Example {
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description: "Define an environment variable in a module",
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example: r#"module foo { export-env { $env.FOO = "BAZ" } }; use foo; $env.FOO"#,
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result: Some(Value::test_string("BAZ")),
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},
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Example {
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description: "Define a custom command that participates in the environment in a module and call it",
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example: r#"module foo { export def --env bar [] { $env.FOO_BAR = "BAZ" } }; use foo bar; bar; $env.FOO_BAR"#,
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result: Some(Value::test_string("BAZ")),
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},
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]
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}
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}
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