438062d7fc
# Description The `ShellError` enum at the moment is kind of messy. Many variants are basic tuple structs where you always have to reference the implementation with its macro invocation to know which field serves which purpose. Furthermore we have both variants that are kind of redundant or either overly broad to be useful for the user to match on or overly specific with few uses. So I set out to start fixing the lacking documentation and naming to make it feasible to critically review the individual usages and fix those. Furthermore we can decide to join or split up variants that don't seem to be fit for purpose. Feel free to add review comments if you spot inconsistent use of `ShellError` variants. - Name fields on `ShellError::OperatorOverflow` - Name fields on `ShellError::PipelineMismatch` - Add doc to `ShellError::OnlySupportsThisInputType` - Name `ShellError::OnlySupportsThisInputType` - Name field on `ShellError::PipelineEmpty` - Comment about issues with `TypeMismatch*` - Fix a few `exp_input_type`s - Name fields on `ShellError::InvalidRange` # User-Facing Changes (None now, end goal more explicit and consistent error messages) # Tests + Formatting (No additional tests needed so far)
313 lines
11 KiB
Rust
313 lines
11 KiB
Rust
use crate::input_handler::{operate, CmdArgument};
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use nu_engine::CallExt;
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use nu_protocol::ast::Call;
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use nu_protocol::ast::CellPath;
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use nu_protocol::engine::{Command, EngineState, Stack};
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use nu_protocol::{
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Category, Example, PipelineData, ShellError, Signature, Span, SyntaxShape, Type, Value,
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};
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use std::cmp::Ordering;
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#[derive(Clone)]
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pub struct BytesAt;
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struct Arguments {
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start: isize,
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end: isize,
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arg_span: Span,
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cell_paths: Option<Vec<CellPath>>,
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}
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impl CmdArgument for Arguments {
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fn take_cell_paths(&mut self) -> Option<Vec<CellPath>> {
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self.cell_paths.take()
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}
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}
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/// ensure given `range` is valid, and returns [start, end, val_span] pair.
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fn parse_range(range: Value, head: Span) -> Result<(isize, isize, Span), ShellError> {
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let (start, end, span) = match range {
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Value::List { mut vals, span } => {
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if vals.len() != 2 {
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return Err(ShellError::UnsupportedInput(
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"More than two indices in range".to_string(),
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"value originates from here".to_string(),
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head,
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span,
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));
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} else {
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let end = vals.pop().expect("Already check has size 2");
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let end = match end {
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Value::Int { val, .. } => val.to_string(),
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Value::String { val, .. } => val,
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// Explicitly propagate errors instead of dropping them.
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Value::Error { error } => return Err(error),
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other => {
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return Err(ShellError::UnsupportedInput(
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"Only string or list<int> ranges are supported".into(),
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format!("input type: {:?}", other.get_type()),
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head,
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other.expect_span(),
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))
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}
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};
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let start = vals.pop().expect("Already check has size 1");
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let start = match start {
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Value::Int { val, .. } => val.to_string(),
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Value::String { val, .. } => val,
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// Explicitly propagate errors instead of dropping them.
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Value::Error { error } => return Err(error),
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other => {
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return Err(ShellError::UnsupportedInput(
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"Only string or list<int> ranges are supported".into(),
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format!("input type: {:?}", other.get_type()),
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head,
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other.expect_span(),
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))
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}
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};
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(start, end, span)
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}
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}
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Value::String { val, span } => {
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let split_result = val.split_once(',');
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match split_result {
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Some((start, end)) => (start.to_string(), end.to_string(), span),
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None => {
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return Err(ShellError::UnsupportedInput(
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"could not perform subbytes".to_string(),
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"with this range".to_string(),
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head,
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span,
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))
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}
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}
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}
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// Explicitly propagate errors instead of dropping them.
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Value::Error { error } => return Err(error),
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other => {
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return Err(ShellError::UnsupportedInput(
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"could not perform subbytes".to_string(),
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"with this range".to_string(),
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head,
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other.expect_span(),
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))
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}
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};
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let start: isize = if start.is_empty() || start == "_" {
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0
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} else {
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start.trim().parse().map_err(|_| {
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ShellError::UnsupportedInput(
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"could not perform subbytes".to_string(),
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"with this range".to_string(),
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head,
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span,
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)
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})?
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};
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let end: isize = if end.is_empty() || end == "_" {
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isize::max_value()
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} else {
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end.trim().parse().map_err(|_| {
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ShellError::UnsupportedInput(
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"could not perform subbytes".to_string(),
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"with this range".to_string(),
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head,
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span,
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)
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})?
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};
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Ok((start, end, span))
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}
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impl Command for BytesAt {
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fn name(&self) -> &str {
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"bytes at"
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}
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fn signature(&self) -> Signature {
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Signature::build("bytes at")
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.input_output_types(vec![(Type::Binary, Type::Binary)])
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.vectorizes_over_list(true)
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.required("range", SyntaxShape::Any, "the indexes to get bytes")
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.rest(
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"rest",
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SyntaxShape::CellPath,
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"for a data structure input, get bytes from data at the given cell paths",
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)
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.category(Category::Bytes)
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}
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fn usage(&self) -> &str {
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"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."
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}
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fn search_terms(&self) -> Vec<&str> {
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vec!["slice"]
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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<PipelineData, ShellError> {
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let range: Value = call.req(engine_state, stack, 0)?;
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let (start, end, arg_span) = parse_range(range, call.head)?;
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let cell_paths: Vec<CellPath> = call.rest(engine_state, stack, 1)?;
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let cell_paths = (!cell_paths.is_empty()).then_some(cell_paths);
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let arg = Arguments {
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start,
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end,
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arg_span,
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cell_paths,
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};
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operate(at, arg, input, call.head, engine_state.ctrlc.clone())
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}
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fn examples(&self) -> Vec<Example> {
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vec![
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Example {
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description: "Get a subbytes `0x[10 01]` from the bytes `0x[33 44 55 10 01 13]`",
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example: " 0x[33 44 55 10 01 13] | bytes at [3 4]",
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result: Some(Value::Binary {
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val: vec![0x10],
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span: Span::test_data(),
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}),
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},
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Example {
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description: "Alternatively, you can use the form",
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example: " 0x[33 44 55 10 01 13] | bytes at '3,4'",
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result: Some(Value::Binary {
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val: vec![0x10],
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span: Span::test_data(),
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}),
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},
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Example {
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description: "Drop the last `n` characters from the string",
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example: " 0x[33 44 55 10 01 13] | bytes at ',-3'",
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result: Some(Value::Binary {
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val: vec![0x33, 0x44, 0x55],
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span: Span::test_data(),
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}),
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},
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Example {
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description: "Get the remaining characters from a starting index",
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example: " 0x[33 44 55 10 01 13] | bytes at '3,'",
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result: Some(Value::Binary {
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val: vec![0x10, 0x01, 0x13],
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span: Span::test_data(),
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}),
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},
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Example {
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description: "Get the characters from the beginning until ending index",
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example: " 0x[33 44 55 10 01 13] | bytes at ',4'",
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result: Some(Value::Binary {
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val: vec![0x33, 0x44, 0x55, 0x10],
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span: Span::test_data(),
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}),
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},
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Example {
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description:
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"Or the characters from the beginning until ending index inside a table",
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example: r#" [[ColA ColB ColC]; [0x[11 12 13] 0x[14 15 16] 0x[17 18 19]]] | bytes at "1," ColB ColC"#,
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result: Some(Value::List {
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vals: vec![Value::Record {
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cols: vec!["ColA".to_string(), "ColB".to_string(), "ColC".to_string()],
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vals: vec![
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Value::Binary {
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val: vec![0x11, 0x12, 0x13],
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span: Span::test_data(),
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},
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Value::Binary {
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val: vec![0x15, 0x16],
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span: Span::test_data(),
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},
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Value::Binary {
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val: vec![0x18, 0x19],
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span: Span::test_data(),
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},
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],
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span: Span::test_data(),
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}],
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span: Span::test_data(),
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}),
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},
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]
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}
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}
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fn at(val: &Value, args: &Arguments, span: Span) -> Value {
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match val {
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Value::Binary {
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val,
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span: val_span,
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} => at_impl(val, args, *val_span),
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// Propagate errors by explicitly matching them before the final case.
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Value::Error { .. } => val.clone(),
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other => Value::Error {
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error: ShellError::OnlySupportsThisInputType {
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exp_input_type: "binary".into(),
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wrong_type: other.get_type().to_string(),
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dst_span: span,
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src_span: other.expect_span(),
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},
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},
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}
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}
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fn at_impl(input: &[u8], arg: &Arguments, span: Span) -> Value {
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let len: isize = input.len() as isize;
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let start: isize = if arg.start < 0 {
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arg.start + len
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} else {
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arg.start
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};
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let end: isize = if arg.end < 0 {
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std::cmp::max(len + arg.end, 0)
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} else {
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arg.end
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};
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if start < len && end >= 0 {
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match start.cmp(&end) {
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Ordering::Equal => Value::Binary { val: vec![], span },
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Ordering::Greater => Value::Error {
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error: ShellError::TypeMismatch(
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"End must be greater than or equal to Start".to_string(),
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arg.arg_span,
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),
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},
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Ordering::Less => Value::Binary {
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val: {
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let input_iter = input.iter().copied().skip(start as usize);
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if end == isize::max_value() {
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input_iter.collect()
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} else {
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input_iter.take((end - start) as usize).collect()
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}
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},
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span,
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},
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}
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} else {
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Value::Binary { val: vec![], span }
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}
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}
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#[cfg(test)]
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mod tests {
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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(BytesAt {})
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}
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}
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