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starts_with.rs
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starts_with.rs
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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::boolean(true, 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::boolean(true, 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::boolean(false, Span::test_data())),
},
]
}
}
fn starts_with(val: &Value, args: &Arguments, span: Span) -> Value {
match val {
Value::Binary {
val,
span: val_span,
} => Value::boolean(val.starts_with(&args.pattern), *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 {})
}
}