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, Example, PipelineData, ShellError, Signature, Span, SyntaxShape, Type, Value,
};
use std::cmp::Ordering;
#[derive(Clone)]
pub struct BytesAt;
struct Arguments {
start: isize,
end: isize,
arg_span: Span,
cell_paths: Option<Vec<CellPath>>,
}
impl CmdArgument for Arguments {
fn take_cell_paths(&mut self) -> Option<Vec<CellPath>> {
self.cell_paths.take()
}
}
fn parse_range(range: Value, head: Span) -> Result<(isize, isize, Span), ShellError> {
let (start, end, span) = match range {
Value::List { mut vals, span } => {
if vals.len() != 2 {
return Err(ShellError::UnsupportedInput(
"More than two indices in range".to_string(),
"value originates from here".to_string(),
head,
span,
));
} else {
let end = vals.pop().expect("Already check has size 2");
let end = match end {
Value::Int { val, .. } => val.to_string(),
Value::String { val, .. } => val,
Value::Error { error } => return Err(error),
other => {
return Err(ShellError::UnsupportedInput(
"Only string or list<int> ranges are supported".into(),
format!("input type: {:?}", other.get_type()),
head,
other.expect_span(),
))
}
};
let start = vals.pop().expect("Already check has size 1");
let start = match start {
Value::Int { val, .. } => val.to_string(),
Value::String { val, .. } => val,
Value::Error { error } => return Err(error),
other => {
return Err(ShellError::UnsupportedInput(
"Only string or list<int> ranges are supported".into(),
format!("input type: {:?}", other.get_type()),
head,
other.expect_span(),
))
}
};
(start, end, span)
}
}
Value::String { val, span } => {
let split_result = val.split_once(',');
match split_result {
Some((start, end)) => (start.to_string(), end.to_string(), span),
None => {
return Err(ShellError::UnsupportedInput(
"could not perform subbytes".to_string(),
"with this range".to_string(),
head,
span,
))
}
}
}
Value::Error { error } => return Err(error),
other => {
return Err(ShellError::UnsupportedInput(
"could not perform subbytes".to_string(),
"with this range".to_string(),
head,
other.expect_span(),
))
}
};
let start: isize = if start.is_empty() || start == "_" {
0
} else {
start.trim().parse().map_err(|_| {
ShellError::UnsupportedInput(
"could not perform subbytes".to_string(),
"with this range".to_string(),
head,
span,
)
})?
};
let end: isize = if end.is_empty() || end == "_" {
isize::max_value()
} else {
end.trim().parse().map_err(|_| {
ShellError::UnsupportedInput(
"could not perform subbytes".to_string(),
"with this range".to_string(),
head,
span,
)
})?
};
Ok((start, end, span))
}
impl Command for BytesAt {
fn name(&self) -> &str {
"bytes at"
}
fn signature(&self) -> Signature {
Signature::build("bytes at")
.input_output_types(vec![(Type::Binary, Type::Binary)])
.vectorizes_over_list(true)
.required("range", SyntaxShape::Any, "the indexes to get bytes")
.rest(
"rest",
SyntaxShape::CellPath,
"for a data structure input, get bytes from data at the given cell paths",
)
.category(Category::Bytes)
}
fn usage(&self) -> &str {
"Get bytes defined by a range. Note that the start is included but the end is excluded, and that the first byte is index 0."
}
fn search_terms(&self) -> Vec<&str> {
vec!["slice"]
}
fn run(
&self,
engine_state: &EngineState,
stack: &mut Stack,
call: &Call,
input: PipelineData,
) -> Result<PipelineData, ShellError> {
let range: Value = call.req(engine_state, stack, 0)?;
let (start, end, arg_span) = parse_range(range, call.head)?;
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 {
start,
end,
arg_span,
cell_paths,
};
operate(at, arg, input, call.head, engine_state.ctrlc.clone())
}
fn examples(&self) -> Vec<Example> {
vec![
Example {
description: "Get a subbytes `0x[10 01]` from the bytes `0x[33 44 55 10 01 13]`",
example: " 0x[33 44 55 10 01 13] | bytes at [3 4]",
result: Some(Value::Binary {
val: vec![0x10],
span: Span::test_data(),
}),
},
Example {
description: "Alternatively, you can use the form",
example: " 0x[33 44 55 10 01 13] | bytes at '3,4'",
result: Some(Value::Binary {
val: vec![0x10],
span: Span::test_data(),
}),
},
Example {
description: "Drop the last `n` characters from the string",
example: " 0x[33 44 55 10 01 13] | bytes at ',-3'",
result: Some(Value::Binary {
val: vec![0x33, 0x44, 0x55],
span: Span::test_data(),
}),
},
Example {
description: "Get the remaining characters from a starting index",
example: " 0x[33 44 55 10 01 13] | bytes at '3,'",
result: Some(Value::Binary {
val: vec![0x10, 0x01, 0x13],
span: Span::test_data(),
}),
},
Example {
description: "Get the characters from the beginning until ending index",
example: " 0x[33 44 55 10 01 13] | bytes at ',4'",
result: Some(Value::Binary {
val: vec![0x33, 0x44, 0x55, 0x10],
span: Span::test_data(),
}),
},
Example {
description:
"Or the characters from the beginning until ending index inside a table",
example: r#" [[ColA ColB ColC]; [0x[11 12 13] 0x[14 15 16] 0x[17 18 19]]] | bytes at "1," ColB ColC"#,
result: Some(Value::List {
vals: vec![Value::Record {
cols: vec!["ColA".to_string(), "ColB".to_string(), "ColC".to_string()],
vals: vec![
Value::Binary {
val: vec![0x11, 0x12, 0x13],
span: Span::test_data(),
},
Value::Binary {
val: vec![0x15, 0x16],
span: Span::test_data(),
},
Value::Binary {
val: vec![0x18, 0x19],
span: Span::test_data(),
},
],
span: Span::test_data(),
}],
span: Span::test_data(),
}),
},
]
}
}
fn at(val: &Value, args: &Arguments, span: Span) -> Value {
match val {
Value::Binary {
val,
span: val_span,
} => at_impl(val, args, *val_span),
Value::Error { .. } => val.clone(),
other => Value::Error {
error: ShellError::OnlySupportsThisInputType(
"integer".into(),
other.get_type().to_string(),
span,
other.expect_span(),
),
},
}
}
fn at_impl(input: &[u8], arg: &Arguments, span: Span) -> Value {
let len: isize = input.len() as isize;
let start: isize = if arg.start < 0 {
arg.start + len
} else {
arg.start
};
let end: isize = if arg.end < 0 {
std::cmp::max(len + arg.end, 0)
} else {
arg.end
};
if start < len && end >= 0 {
match start.cmp(&end) {
Ordering::Equal => Value::Binary { val: vec![], span },
Ordering::Greater => Value::Error {
error: ShellError::TypeMismatch(
"End must be greater than or equal to Start".to_string(),
arg.arg_span,
),
},
Ordering::Less => Value::Binary {
val: {
let input_iter = input.iter().copied().skip(start as usize);
if end == isize::max_value() {
input_iter.collect()
} else {
input_iter.take((end - start) as usize).collect()
}
},
span,
},
}
} else {
Value::Binary { val: vec![], span }
}
}
#[cfg(test)]
mod tests {
use super::*;
#[test]
fn test_examples() {
use crate::test_examples;
test_examples(BytesAt {})
}
}