forked from extern/nushell
e4226def16
This commit extracts five new crates:
- nu-source, which contains the core source-code handling logic in Nu,
including Text, Span, and also the pretty.rs-based debug logic
- nu-parser, which is the parser and expander logic
- nu-protocol, which is the bulk of the types and basic conveniences
used by plugins
- nu-errors, which contains ShellError, ParseError and error handling
conveniences
- nu-textview, which is the textview plugin extracted into a crate
One of the major consequences of this refactor is that it's no longer
possible to `impl X for Spanned<Y>` outside of the `nu-source` crate, so
a lot of types became more concrete (Value became a concrete type
instead of Spanned<Value>, for example).
This also turned a number of inherent methods in the main nu crate into
plain functions (impl Value {} became a bunch of functions in the
`value` namespace in `crate::data::value`).
55 lines
1.2 KiB
Rust
55 lines
1.2 KiB
Rust
use crate::commands::WholeStreamCommand;
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use crate::context::CommandRegistry;
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use crate::prelude::*;
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use nu_errors::ShellError;
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use nu_protocol::{Signature, SyntaxShape};
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use nu_source::Tagged;
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pub struct First;
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#[derive(Deserialize)]
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pub struct FirstArgs {
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rows: Option<Tagged<u64>>,
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}
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impl WholeStreamCommand for First {
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fn name(&self) -> &str {
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"first"
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}
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fn signature(&self) -> Signature {
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Signature::build("first").optional(
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"rows",
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SyntaxShape::Int,
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"starting from the front, 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 first 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, first)?.run()
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}
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}
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fn first(
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FirstArgs { rows }: FirstArgs,
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context: RunnableContext,
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) -> Result<OutputStream, ShellError> {
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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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Ok(OutputStream::from_input(
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context.input.values.take(rows_desired),
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))
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}
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