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c747ec75c9
# Description
When implementing a `Command`, one must also import all the types
present in the function signatures for `Command`. This makes it so that
we often import the same set of types in each command implementation
file. E.g., something like this:
```rust
use nu_protocol::ast::Call;
use nu_protocol::engine::{Command, EngineState, Stack};
use nu_protocol::{
record, Category, Example, IntoInterruptiblePipelineData, IntoPipelineData, PipelineData,
ShellError, Signature, Span, Type, Value,
};
```
This PR adds the `nu_engine::command_prelude` module which contains the
necessary and commonly used types to implement a `Command`:
```rust
// command_prelude.rs
pub use crate::CallExt;
pub use nu_protocol::{
ast::{Call, CellPath},
engine::{Command, EngineState, Stack},
record, Category, Example, IntoInterruptiblePipelineData, IntoPipelineData, IntoSpanned,
PipelineData, Record, ShellError, Signature, Span, Spanned, SyntaxShape, Type, Value,
};
```
This should reduce the boilerplate needed to implement a command and
also gives us a place to track the breadth of the `Command` API. I tried
to be conservative with what went into the prelude modules, since it
might be hard/annoying to remove items from the prelude in the future.
Let me know if something should be included or excluded.
112 lines
3.2 KiB
Rust
112 lines
3.2 KiB
Rust
use crate::formats::to::delimited::to_delimited_data;
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use nu_engine::command_prelude::*;
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use nu_protocol::Config;
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#[derive(Clone)]
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pub struct ToCsv;
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impl Command for ToCsv {
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fn name(&self) -> &str {
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"to csv"
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}
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fn signature(&self) -> Signature {
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Signature::build("to csv")
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.input_output_types(vec![
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(Type::Record(vec![]), Type::String),
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(Type::Table(vec![]), Type::String),
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])
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.named(
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"separator",
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SyntaxShape::String,
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"a character to separate columns, defaults to ','",
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Some('s'),
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)
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.switch(
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"noheaders",
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"do not output the columns names as the first row",
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Some('n'),
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)
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.category(Category::Formats)
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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: "Outputs an CSV string representing the contents of this table",
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example: "[[foo bar]; [1 2]] | to csv",
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result: Some(Value::test_string("foo,bar\n1,2\n")),
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},
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Example {
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description: "Outputs an CSV string representing the contents of this table",
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example: "[[foo bar]; [1 2]] | to csv --separator ';' ",
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result: Some(Value::test_string("foo;bar\n1;2\n")),
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},
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Example {
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description: "Outputs an CSV string representing the contents of this record",
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example: "{a: 1 b: 2} | to csv",
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result: Some(Value::test_string("a,b\n1,2\n")),
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},
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]
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}
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fn usage(&self) -> &str {
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"Convert table into .csv text ."
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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 head = call.head;
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let noheaders = call.has_flag(engine_state, stack, "noheaders")?;
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let separator: Option<Spanned<String>> = call.get_flag(engine_state, stack, "separator")?;
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let config = engine_state.get_config();
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to_csv(input, noheaders, separator, head, config)
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}
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}
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fn to_csv(
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input: PipelineData,
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noheaders: bool,
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separator: Option<Spanned<String>>,
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head: Span,
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config: &Config,
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) -> Result<PipelineData, ShellError> {
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let sep = match separator {
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Some(Spanned { item: s, span, .. }) => {
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if s == r"\t" {
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'\t'
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} else {
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let vec_s: Vec<char> = s.chars().collect();
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if vec_s.len() != 1 {
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return Err(ShellError::TypeMismatch {
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err_message: "Expected a single separator char from --separator"
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.to_string(),
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span,
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});
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};
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vec_s[0]
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}
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}
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_ => ',',
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};
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to_delimited_data(noheaders, sep, "CSV", input, head, config)
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}
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#[cfg(test)]
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mod test {
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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(ToCsv {})
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}
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}
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