1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133

use crate::input_handler::{operate, CmdArgument};
use nu_engine::CallExt;
use nu_protocol::ast::Call;
use nu_protocol::ast::CellPath;
use nu_protocol::engine::{Command, EngineState, Stack};
use nu_protocol::Category;
use nu_protocol::{Example, PipelineData, ShellError, Signature, Span, SyntaxShape, Type, Value};

struct Arguments {
    pattern: Vec<u8>,
    cell_paths: Option<Vec<CellPath>>,
}

impl CmdArgument for Arguments {
    fn take_cell_paths(&mut self) -> Option<Vec<CellPath>> {
        self.cell_paths.take()
    }
}

#[derive(Clone)]

pub struct BytesStartsWith;

impl Command for BytesStartsWith {
    fn name(&self) -> &str {
        "bytes starts-with"
    }

    fn signature(&self) -> Signature {
        Signature::build("bytes starts-with")
            .input_output_types(vec![(Type::Binary, Type::Bool)])
            .required("pattern", SyntaxShape::Binary, "the pattern to match")
            .rest(
                "rest",
                SyntaxShape::CellPath,
                "for a data structure input, check if bytes at the given cell paths start with the pattern",
            )
            .category(Category::Bytes)
    }

    fn usage(&self) -> &str {
        "Check if bytes starts with a pattern"
    }

    fn search_terms(&self) -> Vec<&str> {
        vec!["pattern", "match", "find", "search"]
    }

    fn run(
        &self,
        engine_state: &EngineState,
        stack: &mut Stack,
        call: &Call,
        input: PipelineData,
    ) -> Result<PipelineData, ShellError> {
        let pattern: Vec<u8> = call.req(engine_state, stack, 0)?;
        let cell_paths: Vec<CellPath> = call.rest(engine_state, stack, 1)?;
        let cell_paths = (!cell_paths.is_empty()).then_some(cell_paths);
        let arg = Arguments {
            pattern,
            cell_paths,
        };
        operate(
            starts_with,
            arg,
            input,
            call.head,
            engine_state.ctrlc.clone(),
        )
    }

    fn examples(&self) -> Vec<Example> {
        vec![
            Example {
                description: "Checks if binary starts with `0x[1F FF AA]`",
                example: "0x[1F FF AA AA] | bytes starts-with 0x[1F FF AA]",
                result: Some(Value::Bool {
                    val: true,
                    span: Span::test_data(),
                }),
            },
            Example {
                description: "Checks if binary starts with `0x[1F]`",
                example: "0x[1F FF AA AA] | bytes starts-with 0x[1F]",
                result: Some(Value::Bool {
                    val: true,
                    span: Span::test_data(),
                }),
            },
            Example {
                description: "Checks if binary starts with `0x[1F]`",
                example: "0x[1F FF AA AA] | bytes starts-with 0x[11]",
                result: Some(Value::Bool {
                    val: false,
                    span: Span::test_data(),
                }),
            },
        ]
    }
}

fn starts_with(val: &Value, args: &Arguments, span: Span) -> Value {
    match val {
        Value::Binary {
            val,
            span: val_span,
        } => Value::Bool {
            val: val.starts_with(&args.pattern),
            span: *val_span,
        },
        other => Value::Error {
            error: ShellError::UnsupportedInput(
                format!(
                    "Input's type is {}. This command only works with bytes.",
                    other.get_type()
                ),
                span,
            ),
        },
    }
}

#[cfg(test)]
mod tests {
    use super::*;

    #[test]
    fn test_examples() {
        use crate::test_examples;

        test_examples(BytesStartsWith {})
    }
}