forked from extern/nushell
169 lines
5.3 KiB
Rust
169 lines
5.3 KiB
Rust
use nu_engine::{eval_block, eval_expression};
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use nu_protocol::ast::Call;
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use nu_protocol::engine::{Command, EngineState, EvaluationContext, Stack};
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use nu_protocol::{Example, IntoPipelineData, PipelineData, Signature, Span, SyntaxShape, Value};
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#[derive(Clone)]
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pub struct For;
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impl Command for For {
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fn name(&self) -> &str {
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"for"
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}
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fn usage(&self) -> &str {
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"Loop over a range"
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}
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fn signature(&self) -> nu_protocol::Signature {
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Signature::build("for")
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.required(
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"var_name",
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SyntaxShape::VarWithOptType,
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"name of the looping variable",
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)
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.required(
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"range",
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SyntaxShape::Keyword(b"in".to_vec(), Box::new(SyntaxShape::Any)),
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"range of the loop",
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)
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.required(
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"block",
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SyntaxShape::Block(Some(vec![])),
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"the block to run",
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)
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.creates_scope()
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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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let var_id = call.positional[0]
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.as_var()
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.expect("internal error: missing variable");
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let keyword_expr = call.positional[1]
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.as_keyword()
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.expect("internal error: missing keyword");
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let values = eval_expression(engine_state, stack, keyword_expr)?;
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let block = call.positional[2]
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.as_block()
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.expect("internal error: expected block");
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let engine_state = engine_state.clone();
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let mut stack = stack.enter_scope();
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match values {
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Value::List { vals, span } => Ok(vals
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.into_iter()
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.map(move |x| {
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let block = engine_state.get_block(block);
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let mut stack = stack.clone();
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stack.add_var(var_id, x);
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match eval_block(&engine_state, &mut stack, block, PipelineData::new()) {
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Ok(value) => Value::List {
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vals: value.collect(),
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span,
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},
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Err(error) => Value::Error { error },
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}
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})
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.into_pipeline_data()),
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Value::Range { val, span } => Ok(val
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.into_range_iter()?
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.map(move |x| {
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let block = engine_state.get_block(block);
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let mut stack = stack.enter_scope();
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stack.add_var(var_id, x);
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match eval_block(&engine_state, &mut stack, block, PipelineData::new()) {
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Ok(value) => Value::List {
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vals: value.collect(),
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span,
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},
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Err(error) => Value::Error { error },
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}
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})
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.into_pipeline_data()),
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x => {
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let block = engine_state.get_block(block);
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let mut stack = stack.enter_scope();
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stack.add_var(var_id, x);
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eval_block(&engine_state, &mut stack, block, PipelineData::new())
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}
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}
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}
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fn examples(&self) -> Vec<Example> {
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let span = Span::unknown();
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vec![
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Example {
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description: "Echo the square of each integer",
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example: "for x in [1 2 3] { $x * $x }",
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result: Some(Value::List {
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vals: vec![
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Value::Int { val: 1, span },
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Value::Int { val: 4, span },
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Value::Int { val: 9, span },
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],
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span: Span::unknown(),
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}),
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},
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Example {
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description: "Work with elements of a range",
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example: "for $x in 1..3 { $x }",
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result: Some(Value::List {
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vals: vec![
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Value::Int { val: 1, span },
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Value::Int { val: 2, span },
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Value::Int { val: 3, span },
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],
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span: Span::unknown(),
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}),
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},
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// FIXME? Numbered `for` is kinda strange, but was supported in previous nushell
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// Example {
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// description: "Number each item and echo a message",
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// example: "for $it in ['bob' 'fred'] --numbered { $\"($it.index) is ($it.item)\" }",
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// result: Some(Value::List {
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// vals: vec![
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// Value::String {
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// val: "0 is bob".into(),
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// span,
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// },
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// Value::String {
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// val: "0 is fred".into(),
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// span,
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// },
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// ],
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// span: Span::unknown(),
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// }),
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// },
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]
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}
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}
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#[cfg(test)]
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mod test {
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use super::*;
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#[test]
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fn test_examples() {
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use crate::test_examples;
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test_examples(For {})
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}
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}
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