Add math pi and math e constants (#7258)

Currently implemented as commands

Work towards #7073

Add them to the example test harness together with `math round`

crates/nu-command/src/default_context.rs

@@ -405,6 +405,8 @@ pub fn create_default_context() -> EngineState {
             MathStddev,
             MathSum,
             MathVariance,
+            MathPi,
+            MathEuler,
         };
 
         // Network

crates/nu-command/src/example_test.rs

@@ -9,8 +9,8 @@ pub fn test_examples(cmd: impl Command + 'static) {
 #[cfg(test)]
 mod test_examples {
     use super::super::{
-        Ansi, Date, Echo, From, If, Into, LetEnv, Math, Path, Random, Split, SplitColumn, SplitRow,
+        Ansi, Date, Echo, From, If, Into, LetEnv, Math, MathEuler, MathPi, MathRound, Path, Random,
-        Str, StrJoin, StrLength, StrReplace, Url, Wrap,
+        Split, SplitColumn, SplitRow, Str, StrJoin, StrLength, StrReplace, Url, Wrap,
     };
     use crate::{Break, Mut, To};
     use itertools::Itertools;
@@ -82,6 +82,9 @@ mod test_examples {
             working_set.add_decl(Box::new(Echo));
             working_set.add_decl(Box::new(Break));
             working_set.add_decl(Box::new(Mut));
+            working_set.add_decl(Box::new(MathEuler));
+            working_set.add_decl(Box::new(MathPi));
+            working_set.add_decl(Box::new(MathRound));
             // Adding the command that is being tested to the working set
             working_set.add_decl(cmd);
 

crates/nu-command/src/math/euler.rs

@@ -0,0 +1,61 @@
+use nu_protocol::ast::Call;
+use nu_protocol::engine::{Command, EngineState, Stack};
+use nu_protocol::{Category, Example, IntoPipelineData, PipelineData, Signature, Type, Value};
+
+#[derive(Clone)]
+pub struct SubCommand;
+
+impl Command for SubCommand {
+    fn name(&self) -> &str {
+        "math e"
+    }
+
+    fn signature(&self) -> Signature {
+        Signature::build("math e")
+            .input_output_types(vec![(Type::Any, Type::Float)])
+            .category(Category::Math)
+    }
+
+    fn usage(&self) -> &str {
+        "Returns the mathematical constant π."
+    }
+
+    fn search_terms(&self) -> Vec<&str> {
+        vec!["euler", "constant"]
+    }
+
+    #[allow(clippy::approx_constant)]
+    fn examples(&self) -> Vec<Example> {
+        vec![Example {
+            example: "math e | math round --precision 3",
+            description: "Get the first three decimal digits of e",
+            result: Some(Value::test_float(2.718)),
+        }]
+    }
+
+    fn run(
+        &self,
+        _engine_state: &EngineState,
+        _stack: &mut Stack,
+        call: &Call,
+        _input: PipelineData,
+    ) -> Result<nu_protocol::PipelineData, nu_protocol::ShellError> {
+        Ok(Value::Float {
+            val: std::f64::consts::E,
+            span: call.head,
+        }
+        .into_pipeline_data())
+    }
+}
+
+#[cfg(test)]
+mod test {
+    use super::*;
+
+    #[test]
+    fn test_examples() {
+        use crate::test_examples;
+
+        test_examples(SubCommand {})
+    }
+}

crates/nu-command/src/math/mod.rs

@@ -1,6 +1,7 @@
 mod abs;
 mod avg;
 mod ceil;
+mod euler;
 mod eval;
 mod floor;
 pub mod math_;
@@ -8,6 +9,7 @@ mod max;
 mod median;
 mod min;
 mod mode;
+mod pi;
 mod product;
 mod reducers;
 mod round;
@@ -33,3 +35,6 @@ pub use sqrt::SubCommand as MathSqrt;
 pub use stddev::SubCommand as MathStddev;
 pub use sum::SubCommand as MathSum;
 pub use variance::SubCommand as MathVariance;
+
+pub use euler::SubCommand as MathEuler;
+pub use pi::SubCommand as MathPi;

crates/nu-command/src/math/pi.rs

@@ -0,0 +1,61 @@
+use nu_protocol::ast::Call;
+use nu_protocol::engine::{Command, EngineState, Stack};
+use nu_protocol::{Category, Example, IntoPipelineData, PipelineData, Signature, Type, Value};
+
+#[derive(Clone)]
+pub struct SubCommand;
+
+impl Command for SubCommand {
+    fn name(&self) -> &str {
+        "math pi"
+    }
+
+    fn signature(&self) -> Signature {
+        Signature::build("math pi")
+            .input_output_types(vec![(Type::Any, Type::Float)])
+            .category(Category::Math)
+    }
+
+    fn usage(&self) -> &str {
+        "Returns the mathematical constant π."
+    }
+
+    fn search_terms(&self) -> Vec<&str> {
+        vec!["trigonometry", "constant"]
+    }
+
+    #[allow(clippy::approx_constant)]
+    fn examples(&self) -> Vec<Example> {
+        vec![Example {
+            example: "math pi | math round --precision 2",
+            description: "Get the first two decimal digits of π",
+            result: Some(Value::test_float(3.14)),
+        }]
+    }
+
+    fn run(
+        &self,
+        _engine_state: &EngineState,
+        _stack: &mut Stack,
+        call: &Call,
+        _input: PipelineData,
+    ) -> Result<nu_protocol::PipelineData, nu_protocol::ShellError> {
+        Ok(Value::Float {
+            val: std::f64::consts::PI,
+            span: call.head,
+        }
+        .into_pipeline_data())
+    }
+}
+
+#[cfg(test)]
+mod test {
+    use super::*;
+
+    #[test]
+    fn test_examples() {
+        use crate::test_examples;
+
+        test_examples(SubCommand {})
+    }
+}