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use nu_engine::CallExt;
use nu_protocol::ast::Call;
use nu_protocol::engine::{Command, EngineState, Stack};
use nu_protocol::{
Category, Example, PipelineData, ShellError, Signature, Span, Spanned, SyntaxShape, Type, Value,
};
#[derive(Clone)]
pub struct SubCommand;
impl Command for SubCommand {
fn name(&self) -> &str {
"math log"
}
fn signature(&self) -> Signature {
Signature::build("math log")
.required(
"base",
SyntaxShape::Number,
"Base for which the logarithm should be computed",
)
.input_output_types(vec![(Type::Number, Type::Float)])
.vectorizes_over_list(true)
.category(Category::Math)
}
fn usage(&self) -> &str {
"Returns the logarithm for an arbitrary base."
}
fn search_terms(&self) -> Vec<&str> {
vec!["base", "exponent", "inverse", "euler"]
}
fn run(
&self,
engine_state: &EngineState,
stack: &mut Stack,
call: &Call,
input: PipelineData,
) -> Result<nu_protocol::PipelineData, nu_protocol::ShellError> {
let head = call.head;
let base: Spanned<f64> = call.req(engine_state, stack, 0)?;
if base.item <= 0.0f64 {
return Err(ShellError::UnsupportedInput(
"Base has to be greater 0".into(),
"value originates from here".into(),
head,
base.span,
));
}
if matches!(input, PipelineData::Empty) {
return Err(ShellError::PipelineEmpty(head));
}
let base = base.item;
input.map(
move |value| operate(value, head, base),
engine_state.ctrlc.clone(),
)
}
fn examples(&self) -> Vec<Example> {
vec![
Example {
description: "Get the logarithm of 100 to the base 10",
example: "100 | math log 10",
result: Some(Value::test_float(2.0f64)),
},
Example {
example: "[16 8 4] | math log 2",
description: "Get the log2 of a list of values",
result: Some(Value::List {
vals: vec![
Value::test_float(4.0),
Value::test_float(3.0),
Value::test_float(2.0),
],
span: Span::test_data(),
}),
},
]
}
}
fn operate(value: Value, head: Span, base: f64) -> Value {
match value {
numeric @ (Value::Int { .. } | Value::Float { .. }) => {
let (val, span) = match numeric {
Value::Int { val, span } => (val as f64, span),
Value::Float { val, span } => (val, span),
_ => unreachable!(),
};
if val <= 0.0 {
return Value::Error {
error: ShellError::UnsupportedInput(
"'math log' undefined for values outside the open interval (0, Inf)."
.into(),
"value originates from here".into(),
head,
span,
),
};
}
let val = if base == 10.0 {
val.log10()
} else if base == 2.0 {
val.log2()
} else {
val.log(base)
};
Value::Float { val, span }
}
Value::Error { .. } => value,
other => Value::Error {
error: ShellError::OnlySupportsThisInputType(
"numeric".into(),
other.get_type().to_string(),
head,
other.expect_span(),
),
},
}
}
#[cfg(test)]
mod test {
use super::*;
#[test]
fn test_examples() {
use crate::test_examples;
test_examples(SubCommand {})
}
}