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use nu_engine::{eval_block, eval_expression, CallExt};
use nu_protocol::ast::Call;
use nu_protocol::engine::{Block, Command, EngineState, Stack};
use nu_protocol::{
Category, Example, ListStream, PipelineData, ShellError, Signature, SyntaxShape, Type, Value,
};
#[derive(Clone)]
pub struct For;
impl Command for For {
fn name(&self) -> &str {
"for"
}
fn usage(&self) -> &str {
"Loop over a range"
}
fn signature(&self) -> nu_protocol::Signature {
Signature::build("for")
.input_output_types(vec![(Type::Nothing, Type::Nothing)])
.allow_variants_without_examples(true)
.required(
"var_name",
SyntaxShape::VarWithOptType,
"name of the looping variable",
)
.required(
"range",
SyntaxShape::Keyword(b"in".to_vec(), Box::new(SyntaxShape::Any)),
"range of the loop",
)
.required("block", SyntaxShape::Block, "the block to run")
.switch(
"numbered",
"returned a numbered item ($it.index and $it.item)",
Some('n'),
)
.creates_scope()
.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_nu.html"#
}
fn is_parser_keyword(&self) -> bool {
true
}
fn run(
&self,
engine_state: &EngineState,
stack: &mut Stack,
call: &Call,
_input: PipelineData,
) -> Result<nu_protocol::PipelineData, nu_protocol::ShellError> {
let head = call.head;
let var_id = call
.positional_nth(0)
.expect("checked through parser")
.as_var()
.expect("internal error: missing variable");
let keyword_expr = call
.positional_nth(1)
.expect("checked through parser")
.as_keyword()
.expect("internal error: missing keyword");
let values = eval_expression(engine_state, stack, keyword_expr)?;
let block: Block = call.req(engine_state, stack, 2)?;
let numbered = call.has_flag("numbered");
let ctrlc = engine_state.ctrlc.clone();
let engine_state = engine_state.clone();
let block = engine_state.get_block(block.block_id).clone();
let redirect_stdout = call.redirect_stdout;
let redirect_stderr = call.redirect_stderr;
match values {
Value::List { vals, .. } => {
for (idx, x) in ListStream::from_stream(vals.into_iter(), ctrlc).enumerate() {
// with_env() is used here to ensure that each iteration uses
// a different set of environment variables.
// Hence, a 'cd' in the first loop won't affect the next loop.
stack.add_var(
var_id,
if numbered {
Value::Record {
cols: vec!["index".into(), "item".into()],
vals: vec![Value::int(idx as i64, head), x],
span: head,
}
} else {
x
},
);
//let block = engine_state.get_block(block_id);
match eval_block(
&engine_state,
stack,
&block,
PipelineData::empty(),
redirect_stdout,
redirect_stderr,
) {
Err(ShellError::Break(_)) => {
break;
}
Err(ShellError::Continue(_)) => {
continue;
}
Err(err) => {
return Err(err);
}
Ok(pipeline) => {
let exit_code = pipeline.print(&engine_state, stack, false, false)?;
if exit_code != 0 {
break;
}
}
}
}
}
Value::Range { val, .. } => {
for (idx, x) in val.into_range_iter(ctrlc)?.enumerate() {
stack.add_var(
var_id,
if numbered {
Value::Record {
cols: vec!["index".into(), "item".into()],
vals: vec![Value::int(idx as i64, head), x],
span: head,
}
} else {
x
},
);
//let block = engine_state.get_block(block_id);
match eval_block(
&engine_state,
stack,
&block,
PipelineData::empty(),
redirect_stdout,
redirect_stderr,
) {
Err(ShellError::Break(_)) => {
break;
}
Err(ShellError::Continue(_)) => {
continue;
}
Err(err) => {
return Err(err);
}
Ok(pipeline) => {
let exit_code = pipeline.print(&engine_state, stack, false, false)?;
if exit_code != 0 {
break;
}
}
}
}
}
x => {
stack.add_var(var_id, x);
eval_block(
&engine_state,
stack,
&block,
PipelineData::empty(),
redirect_stdout,
redirect_stderr,
)?
.into_value(head);
}
}
Ok(PipelineData::empty())
}
fn examples(&self) -> Vec<Example> {
vec![
Example {
description: "Echo the square of each integer",
example: "for x in [1 2 3] { print ($x * $x) }",
result: None,
},
Example {
description: "Work with elements of a range",
example: "for $x in 1..3 { print $x }",
result: None,
},
Example {
description: "Number each item and echo a message",
example:
"for $it in ['bob' 'fred'] --numbered { print $\"($it.index) is ($it.item)\" }",
result: None,
},
]
}
}
#[cfg(test)]
mod test {
use super::*;
#[test]
fn test_examples() {
use crate::test_examples;
test_examples(For {})
}
}