nushell/crates/nu-cli/src/commands/if_.rs

143 lines
4.3 KiB
Rust
Raw Normal View History

2020-07-04 21:40:04 +02:00
use crate::commands::classified::block::run_block;
use crate::commands::WholeStreamCommand;
use crate::evaluate::evaluate_baseline_expr;
use crate::prelude::*;
use nu_errors::ShellError;
use nu_protocol::{
hir::CapturedBlock, hir::ClassifiedCommand, Signature, SyntaxShape, UntaggedValue,
};
2020-07-04 21:40:04 +02:00
pub struct If;
#[derive(Deserialize)]
pub struct IfArgs {
condition: CapturedBlock,
then_case: CapturedBlock,
else_case: CapturedBlock,
2020-07-04 21:40:04 +02:00
}
#[async_trait]
impl WholeStreamCommand for If {
fn name(&self) -> &str {
"if"
}
fn signature(&self) -> Signature {
Signature::build("if")
.required(
"condition",
SyntaxShape::Math,
"the condition that must match",
)
.required(
"then_case",
SyntaxShape::Block,
"block to run if condition is true",
)
.required(
"else_case",
SyntaxShape::Block,
"block to run if condition is false",
)
}
fn usage(&self) -> &str {
2020-07-18 19:16:35 +02:00
"Run blocks if a condition is true or false."
2020-07-04 21:40:04 +02:00
}
async fn run(&self, args: CommandArgs) -> Result<OutputStream, ShellError> {
if_command(args).await
2020-07-04 21:40:04 +02:00
}
fn examples(&self) -> Vec<Example> {
vec![
Example {
description: "Run a block if a condition is true",
example: "set x = 10; if $x > 5 { echo 'greater than 5' } { echo 'less than or equal to 5' }",
2020-07-04 21:40:04 +02:00
result: Some(vec![UntaggedValue::string("greater than 5").into()]),
},
Example {
description: "Run a block if a condition is false",
example: "set x = 1; if $x > 5 { echo 'greater than 5' } { echo 'less than or equal to 5' }",
2020-07-04 21:40:04 +02:00
result: Some(vec![UntaggedValue::string("less than or equal to 5").into()]),
},
]
}
}
async fn if_command(raw_args: CommandArgs) -> Result<OutputStream, ShellError> {
2020-07-04 21:40:04 +02:00
let tag = raw_args.call_info.name_tag.clone();
let context = Arc::new(EvaluationContext::from_raw(&raw_args));
2020-07-04 21:40:04 +02:00
let (
IfArgs {
condition,
then_case,
else_case,
},
input,
) = raw_args.process().await?;
let cond = {
if condition.block.block.len() != 1 {
2020-07-04 21:40:04 +02:00
return Err(ShellError::labeled_error(
"Expected a condition",
"expected a condition",
tag,
));
}
match condition.block.block[0].pipelines.get(0) {
Some(item) => match item.list.get(0) {
Some(ClassifiedCommand::Expr(expr)) => expr.clone(),
2020-07-04 21:40:04 +02:00
_ => {
return Err(ShellError::labeled_error(
"Expected a condition",
"expected a condition",
tag,
));
}
},
None => {
return Err(ShellError::labeled_error(
"Expected a condition",
"expected a condition",
tag,
));
}
}
};
context.scope.enter_scope();
context.scope.add_vars(&condition.captured.entries);
//FIXME: should we use the scope that's brought in as well?
let condition = evaluate_baseline_expr(&cond, &*context).await;
match condition {
Ok(condition) => match condition.as_bool() {
Ok(b) => {
let result = if b {
run_block(&then_case.block, &*context, input).await
} else {
run_block(&else_case.block, &*context, input).await
};
context.scope.exit_scope();
result.map(|x| x.to_output_stream())
2020-07-04 21:40:04 +02:00
}
Err(e) => Ok(futures::stream::iter(vec![Err(e)].into_iter()).to_output_stream()),
},
Err(e) => Ok(futures::stream::iter(vec![Err(e)].into_iter()).to_output_stream()),
}
2020-07-04 21:40:04 +02:00
}
#[cfg(test)]
mod tests {
use super::If;
use super::ShellError;
2020-07-04 21:40:04 +02:00
#[test]
fn examples_work_as_expected() -> Result<(), ShellError> {
2020-07-04 21:40:04 +02:00
use crate::examples::test as test_examples;
Ok(test_examples(If {})?)
2020-07-04 21:40:04 +02:00
}
}