nushell/crates/nu-plugin/src/protocol/evaluated_call.rs
Stefan Holderbach 62575c9a4f
Document and critically review ShellError variants - Ep. 3 (#8340)
Continuation of #8229 and #8326

# 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.

# Call to action

**Everyone:** Feel free to add review comments if you spot inconsistent
use of `ShellError` variants.

# User-Facing Changes

(None now, end goal more explicit and consistent error messages)

# Tests + Formatting

(No additional tests needed so far)

# Commits (so far)

- Remove `ShellError::FeatureNotEnabled`
- Name fields on `SE::ExternalNotSupported`
- Name field on `SE::InvalidProbability`
- Name fields on `SE::NushellFailed` variants
- Remove unused `SE::NushellFailedSpannedHelp`
- Name field on `SE::VariableNotFoundAtRuntime`
- Name fields on `SE::EnvVarNotFoundAtRuntime`
- Name fields on `SE::ModuleNotFoundAtRuntime`
- Remove usused `ModuleOrOverlayNotFoundAtRuntime`
- Name fields on `SE::OverlayNotFoundAtRuntime`
- Name field on `SE::NotFound`
2023-03-06 18:33:09 +01:00

165 lines
4.7 KiB
Rust

use nu_engine::eval_expression;
use nu_protocol::{
ast::Call,
engine::{EngineState, Stack},
FromValue, ShellError, Span, Spanned, Value,
};
use serde::{Deserialize, Serialize};
// The evaluated call is used with the Plugins because the plugin doesn't have
// access to the Stack and the EngineState. For that reason, before encoding the
// message to the plugin all the arguments to the original call (which are expressions)
// are evaluated and passed to Values
#[derive(Debug, Clone, Serialize, Deserialize)]
pub struct EvaluatedCall {
pub head: Span,
pub positional: Vec<Value>,
pub named: Vec<(Spanned<String>, Option<Value>)>,
}
impl EvaluatedCall {
pub fn try_from_call(
call: &Call,
engine_state: &EngineState,
stack: &mut Stack,
) -> Result<Self, ShellError> {
let positional = call
.positional_iter()
.map(|expr| eval_expression(engine_state, stack, expr))
.collect::<Result<Vec<Value>, ShellError>>()?;
let mut named = Vec::with_capacity(call.named_len());
for (string, _, expr) in call.named_iter() {
let value = match expr {
None => None,
Some(expr) => Some(eval_expression(engine_state, stack, expr)?),
};
named.push((string.clone(), value))
}
Ok(Self {
head: call.head,
positional,
named,
})
}
pub fn has_flag(&self, flag_name: &str) -> bool {
for name in &self.named {
if flag_name == name.0.item {
return true;
}
}
false
}
pub fn get_flag_value(&self, flag_name: &str) -> Option<Value> {
for name in &self.named {
if flag_name == name.0.item {
return name.1.clone();
}
}
None
}
pub fn nth(&self, pos: usize) -> Option<Value> {
self.positional.get(pos).cloned()
}
pub fn get_flag<T: FromValue>(&self, name: &str) -> Result<Option<T>, ShellError> {
if let Some(value) = self.get_flag_value(name) {
FromValue::from_value(&value).map(Some)
} else {
Ok(None)
}
}
pub fn rest<T: FromValue>(&self, starting_pos: usize) -> Result<Vec<T>, ShellError> {
self.positional
.iter()
.skip(starting_pos)
.map(|value| FromValue::from_value(value))
.collect()
}
pub fn opt<T: FromValue>(&self, pos: usize) -> Result<Option<T>, ShellError> {
if let Some(value) = self.nth(pos) {
FromValue::from_value(&value).map(Some)
} else {
Ok(None)
}
}
pub fn req<T: FromValue>(&self, pos: usize) -> Result<T, ShellError> {
if let Some(value) = self.nth(pos) {
FromValue::from_value(&value)
} else if self.positional.is_empty() {
Err(ShellError::AccessEmptyContent { span: self.head })
} else {
Err(ShellError::AccessBeyondEnd {
max_idx: self.positional.len() - 1,
span: self.head,
})
}
}
}
#[cfg(test)]
mod test {
use super::*;
use nu_protocol::{Span, Spanned, Value};
#[test]
fn call_to_value() {
let call = EvaluatedCall {
head: Span::new(0, 10),
positional: vec![
Value::Float {
val: 1.0,
span: Span::new(0, 10),
},
Value::String {
val: "something".into(),
span: Span::new(0, 10),
},
],
named: vec![
(
Spanned {
item: "name".to_string(),
span: Span::new(0, 10),
},
Some(Value::Float {
val: 1.0,
span: Span::new(0, 10),
}),
),
(
Spanned {
item: "flag".to_string(),
span: Span::new(0, 10),
},
None,
),
],
};
let name: Option<f64> = call.get_flag("name").unwrap();
assert_eq!(name, Some(1.0));
assert!(call.has_flag("flag"));
let required: f64 = call.req(0).unwrap();
assert!((required - 1.0).abs() < f64::EPSILON);
let optional: Option<String> = call.opt(1).unwrap();
assert_eq!(optional, Some("something".to_string()));
let rest: Vec<String> = call.rest(1).unwrap();
assert_eq!(rest, vec!["something".to_string()]);
}
}