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https://github.com/nushell/nushell.git
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f70c6d5d48
This commit extracts Tag, Span, Text, as well as source-related debug facilities into a new crate called nu_source. This change is much bigger than one might have expected because the previous code relied heavily on implementing inherent methods on `Tagged<T>` and `Spanned<T>`, which is no longer possible. As a result, this change creates more concrete types instead of using `Tagged<T>`. One notable example: Tagged<Value> became Value, and Value became UntaggedValue. This change clarifies the intent of the code in many places, but it does make it a big change.
61 lines
1.4 KiB
Rust
61 lines
1.4 KiB
Rust
use crate::commands::WholeStreamCommand;
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use crate::errors::ShellError;
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use crate::parser::CommandRegistry;
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use crate::prelude::*;
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use nu_source::Tagged;
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pub struct Last;
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#[derive(Deserialize)]
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pub struct LastArgs {
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rows: Option<Tagged<u64>>,
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}
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impl WholeStreamCommand for Last {
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fn name(&self) -> &str {
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"last"
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}
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fn signature(&self) -> Signature {
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Signature::build("last").optional(
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"rows",
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SyntaxShape::Number,
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"starting from the back, the number of rows to return",
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)
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}
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fn usage(&self) -> &str {
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"Show only the last number of rows."
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}
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fn run(
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&self,
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args: CommandArgs,
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registry: &CommandRegistry,
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) -> Result<OutputStream, ShellError> {
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args.process(registry, last)?.run()
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}
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}
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fn last(LastArgs { rows }: LastArgs, context: RunnableContext) -> Result<OutputStream, ShellError> {
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let stream = async_stream! {
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let v: Vec<_> = context.input.into_vec().await;
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let rows_desired = if let Some(quantity) = rows {
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*quantity
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} else {
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1
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};
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let count = (rows_desired as usize);
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if count < v.len() {
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let k = v.len() - count;
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for x in v[k..].iter() {
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let y: Value = x.clone();
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yield ReturnSuccess::value(y)
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}
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}
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};
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Ok(stream.to_output_stream())
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}
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