2021-09-29 20:25:05 +02:00
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use nu_engine::{eval_block, eval_expression};
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use nu_protocol::ast::Call;
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2021-10-25 18:58:58 +02:00
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use nu_protocol::engine::{Command, EngineState, Stack};
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2021-10-25 06:01:02 +02:00
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use nu_protocol::{IntoPipelineData, PipelineData, ShellError, Signature, SyntaxShape, Value};
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2021-09-29 20:25:05 +02:00
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2021-10-25 06:01:02 +02:00
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#[derive(Clone)]
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2021-09-29 20:25:05 +02:00
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pub struct If;
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impl Command for If {
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fn name(&self) -> &str {
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"if"
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}
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fn usage(&self) -> &str {
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"Conditionally run a block."
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}
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fn signature(&self) -> nu_protocol::Signature {
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Signature::build("if")
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.required("cond", SyntaxShape::Expression, "condition")
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.required("then_block", SyntaxShape::Block(Some(vec![])), "then block")
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.optional(
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"else",
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SyntaxShape::Keyword(b"else".to_vec(), Box::new(SyntaxShape::Expression)),
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"optional else followed by else block",
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)
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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<nu_protocol::PipelineData, nu_protocol::ShellError> {
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2021-09-29 20:25:05 +02:00
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let cond = &call.positional[0];
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let then_block = call.positional[1]
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.as_block()
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.expect("internal error: expected block");
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let else_case = call.positional.get(2);
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2021-10-25 08:31:39 +02:00
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let result = eval_expression(engine_state, stack, cond)?;
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match &result {
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Value::Bool { val, .. } => {
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if *val {
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let block = engine_state.get_block(then_block);
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2021-10-25 22:04:23 +02:00
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let mut stack = stack.collect_captures(&block.captures);
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eval_block(engine_state, &mut stack, block, input)
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} else if let Some(else_case) = else_case {
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if let Some(else_expr) = else_case.as_keyword() {
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if let Some(block_id) = else_expr.as_block() {
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2021-10-25 08:31:39 +02:00
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let block = engine_state.get_block(block_id);
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let mut stack = stack.collect_captures(&block.captures);
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eval_block(engine_state, &mut stack, block, input)
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} else {
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eval_expression(engine_state, stack, else_expr)
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.map(|x| x.into_pipeline_data())
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}
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} else {
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eval_expression(engine_state, stack, else_case)
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.map(|x| x.into_pipeline_data())
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}
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} else {
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Ok(PipelineData::new(call.head))
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}
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}
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2021-11-06 06:50:33 +01:00
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x => Err(ShellError::CantConvert(
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"bool".into(),
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x.get_type().to_string(),
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result.span()?,
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)),
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}
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}
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}
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