nu_cmd_lang/core_commands/
for_.rs

1use nu_engine::command_prelude::*;
2use nu_protocol::engine::CommandType;
3
4#[derive(Clone)]
5pub struct For;
6
7impl Command for For {
8    fn name(&self) -> &str {
9        "for"
10    }
11
12    fn description(&self) -> &str {
13        "Loop over a range."
14    }
15
16    fn signature(&self) -> nu_protocol::Signature {
17        Signature::build("for")
18            .input_output_types(vec![(Type::Nothing, Type::Nothing)])
19            .allow_variants_without_examples(true)
20            .required(
21                "var_name",
22                SyntaxShape::VarWithOptType,
23                "Name of the looping variable.",
24            )
25            .required(
26                "range",
27                SyntaxShape::Keyword(b"in".to_vec(), Box::new(SyntaxShape::Any)),
28                "Range of the loop.",
29            )
30            .required("block", SyntaxShape::Block, "The block to run.")
31            .category(Category::Core)
32    }
33
34    fn extra_description(&self) -> &str {
35        r#"This command is a parser keyword. For details, check:
36  https://www.nushell.sh/book/thinking_in_nu.html"#
37    }
38
39    fn command_type(&self) -> CommandType {
40        CommandType::Keyword
41    }
42
43    fn run(
44        &self,
45        _engine_state: &EngineState,
46        _stack: &mut Stack,
47        _call: &Call,
48        _input: PipelineData,
49    ) -> Result<PipelineData, ShellError> {
50        // This is compiled specially by the IR compiler. The code here is never used when
51        // running in IR mode.
52        eprintln!(
53            "Tried to execute 'run' for the 'for' command: this code path should never be reached in IR mode"
54        );
55        unreachable!()
56    }
57
58    fn examples(&self) -> Vec<Example<'_>> {
59        vec![
60            Example {
61                description: "Print the square of each integer",
62                example: "for x in [1 2 3] { print ($x * $x) }",
63                result: None,
64            },
65            Example {
66                description: "Work with elements of a range",
67                example: "for $x in 1..3 { print $x }",
68                result: None,
69            },
70            Example {
71                description: "Number each item and print a message",
72                example: r#"for $it in (['bob' 'fred'] | enumerate) { print $"($it.index) is ($it.item)" }"#,
73                result: None,
74            },
75        ]
76    }
77}
78
79#[cfg(test)]
80mod test {
81    use super::*;
82
83    #[test]
84    fn test_examples() {
85        use crate::test_examples;
86
87        test_examples(For {})
88    }
89}
nu_cmd_lang/core_commands/for_.rs

nu_cmd_lang/core_commands/
for_.rs
