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