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use nu_engine::eval_block;
use nu_protocol::ast::{Call, Expr, Expression, ImportPatternMember};
use nu_protocol::engine::{Command, EngineState, Stack};
use nu_protocol::{
Category, Example, PipelineData, ShellError, Signature, Span, SyntaxShape, Value,
};
#[derive(Clone)]
pub struct Use;
impl Command for Use {
fn name(&self) -> &str {
"use"
}
fn usage(&self) -> &str {
"Use definitions from a module"
}
fn signature(&self) -> nu_protocol::Signature {
Signature::build("use")
.required("pattern", SyntaxShape::ImportPattern, "import pattern")
.category(Category::Core)
}
fn extra_usage(&self) -> &str {
r#"This command is a parser keyword. For details, check:
https://www.nushell.sh/book/thinking_in_nushell.html"#
}
fn is_parser_keyword(&self) -> bool {
true
}
fn run(
&self,
engine_state: &EngineState,
stack: &mut Stack,
call: &Call,
_input: PipelineData,
) -> Result<PipelineData, ShellError> {
let import_pattern = if let Some(Expression {
expr: Expr::ImportPattern(pat),
..
}) = call.positional_nth(0)
{
pat
} else {
return Err(ShellError::GenericError(
"Unexpected import".into(),
"import pattern not supported".into(),
Some(call.head),
None,
Vec::new(),
));
};
if let Some(module_id) = import_pattern.head.id {
let module = engine_state.get_module(module_id);
let env_vars_to_use = if import_pattern.members.is_empty() {
module.env_vars_with_head(&import_pattern.head.name)
} else {
match &import_pattern.members[0] {
ImportPatternMember::Glob { .. } => module.env_vars(),
ImportPatternMember::Name { name, span } => {
let mut output = vec![];
if let Some(id) = module.get_env_var_id(name) {
output.push((name.clone(), id));
} else if !module.has_decl(name) && !module.has_alias(name) {
return Err(ShellError::EnvVarNotFoundAtRuntime(
String::from_utf8_lossy(name).into(),
*span,
));
}
output
}
ImportPatternMember::List { names } => {
let mut output = vec![];
for (name, span) in names {
if let Some(id) = module.get_env_var_id(name) {
output.push((name.clone(), id));
} else if !module.has_decl(name) && !module.has_alias(name) {
return Err(ShellError::EnvVarNotFoundAtRuntime(
String::from_utf8_lossy(name).into(),
*span,
));
}
}
output
}
}
};
for (name, block_id) in env_vars_to_use {
let name = if let Ok(s) = String::from_utf8(name.clone()) {
s
} else {
return Err(ShellError::NonUtf8(import_pattern.head.span));
};
let block = engine_state.get_block(block_id);
let val = eval_block(
engine_state,
stack,
block,
PipelineData::new(call.head),
false,
true,
)?
.into_value(call.head);
stack.add_env_var(name, val);
}
} else {
return Err(ShellError::GenericError(
format!(
"Could not import from '{}'",
String::from_utf8_lossy(&import_pattern.head.name)
),
"module does not exist".to_string(),
Some(import_pattern.head.span),
None,
Vec::new(),
));
}
Ok(PipelineData::new(call.head))
}
fn examples(&self) -> Vec<Example> {
vec![
Example {
description: "Define a custom command in a module and call it",
example: r#"module spam { export def foo [] { "foo" } }; use spam foo; foo"#,
result: Some(Value::String {
val: "foo".to_string(),
span: Span::test_data(),
}),
},
Example {
description: "Define an environment variable in a module and evaluate it",
example: r#"module foo { export env FOO_ENV { "BAZ" } }; use foo FOO_ENV; $env.FOO_ENV"#,
result: Some(Value::String {
val: "BAZ".to_string(),
span: Span::test_data(),
}),
},
Example {
description: "Define a custom command that participates in the environment in a module and call it",
example: r#"module foo { export def-env bar [] { let-env FOO_BAR = "BAZ" } }; use foo bar; bar; $env.FOO_BAR"#,
result: Some(Value::String {
val: "BAZ".to_string(),
span: Span::test_data(),
}),
},
]
}
}
