Remove math eval command (#7284)

Reasoning: 

Most missing math commands are implemented with #7258.
The `meval` crate itself declares that it doesn't strive to stringent
standards (https://docs.rs/meval/latest/meval/#related-projects).
For example no particular special casing or transformations are
performed to ensure numerical stability. It uses the same rust `std`
library functions we use or have access to (and `f64`).
While the command call syntax in nushell may be a bit more verbose,
having a single source of truth and common commands is beneficial.
Furthermore the `math` commands can themselves implement broadcasting
over lists (or table columns).

Closes #7073

Removed dependencies:
- `meval`
- `nom 1.2.4` (duplicate)

User-Facing Changes:

Scripts using `math eval` will break. 
We remove a further `eval` like behavior to get results through runtime evaluation (albeit limited in scope)

Tests:

- Updated tests that internally used `math eval`.
- Removed one test that primarily used `math eval` to obtain a result from `str join`

Cargo.lock

@@ -104,7 +104,7 @@ version = "0.2.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "220044e6a1bb31ddee4e3db724d29767f352de47445a6cd75e1a173142136c83"
 dependencies = [
- "nom 7.1.1",
+ "nom",
  "vte",
 ]
 
@@ -479,7 +479,7 @@ version = "0.6.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "6fac387a98bb7c37292057cffc56d62ecb629900026402633ae9160df93a8766"
 dependencies = [
- "nom 7.1.1",
+ "nom",
 ]
 
 [[package]]
@@ -2225,16 +2225,6 @@ dependencies = [
  "autocfg",
 ]
 
-[[package]]
-name = "meval"
-version = "0.2.0"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "f79496a5651c8d57cd033c5add8ca7ee4e3d5f7587a4777484640d9cb60392d9"
-dependencies = [
- "fnv",
- "nom 1.2.4",
-]
-
 [[package]]
 name = "miette"
 version = "5.3.0"
@@ -2439,12 +2429,6 @@ version = "0.1.14"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "72ef4a56884ca558e5ddb05a1d1e7e1bfd9a68d9ed024c21704cc98872dae1bb"
 
-[[package]]
-name = "nom"
-version = "1.2.4"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "a5b8c256fd9471521bcb84c3cdba98921497f1a331cbc15b8030fc63b82050ce"
-
 [[package]]
 name = "nom"
 version = "7.1.1"
@@ -2465,7 +2449,7 @@ dependencies = [
  "indent_write",
  "joinery",
  "memchr",
- "nom 7.1.1",
+ "nom",
 ]
 
 [[package]]
@@ -2628,7 +2612,6 @@ dependencies = [
  "log",
  "lscolors",
  "md-5",
- "meval",
  "mime",
  "mime_guess",
  "notify",
@@ -3672,7 +3655,7 @@ version = "0.0.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "a4a63d338dec139f56dacc692ca63ad35a6be6a797442479b55acd611d79e906"
 dependencies = [
- "nom 7.1.1",
+ "nom",
 ]
 
 [[package]]
@@ -5574,7 +5557,7 @@ dependencies = [
  "bstr",
  "const_format",
  "itertools",
- "nom 7.1.1",
+ "nom",
  "nom-supreme",
  "pori",
  "regex",

crates/nu-command/Cargo.toml

@@ -57,7 +57,6 @@ itertools = "0.10.0"
 log = "0.4.14"
 lscolors = { version = "0.12.0", features = ["crossterm"], default-features = false }
 md5 = { package = "md-5", version = "0.10.0" }
-meval = "0.2.0"
 mime = "0.3.16"
 mime_guess = "2.0.4"
 notify = "4.0.17"

crates/nu-command/src/default_context.rs

@@ -401,7 +401,6 @@ pub fn create_default_context() -> EngineState {
             MathAbs,
             MathAvg,
             MathCeil,
-            MathEval,
             MathFloor,
             MathMax,
             MathMedian,
@@ -481,6 +480,7 @@ pub fn create_default_context() -> EngineState {
             StrDecimalDeprecated,
             StrIntDeprecated,
             StrFindReplaceDeprecated,
+            MathEvalDeprecated,
         };
 
         #[cfg(feature = "plugin")]

crates/nu-command/src/deprecated/math_eval.rs

@@ -0,0 +1,40 @@
+use nu_protocol::ast::Call;
+use nu_protocol::engine::{Command, EngineState, Stack};
+use nu_protocol::{Category, PipelineData, ShellError, Signature, SyntaxShape};
+
+#[derive(Clone)]
+pub struct SubCommand;
+
+impl Command for SubCommand {
+    fn name(&self) -> &str {
+        "math eval"
+    }
+
+    fn signature(&self) -> Signature {
+        Signature::build("math eval")
+            .rest(
+                "ignored",
+                SyntaxShape::Any,
+                "arguments to deprecated command are ignored",
+            )
+            .category(Category::Deprecated)
+    }
+
+    fn usage(&self) -> &str {
+        "Deprecated command"
+    }
+
+    fn run(
+        &self,
+        _engine_state: &EngineState,
+        _stack: &mut Stack,
+        call: &Call,
+        _input: PipelineData,
+    ) -> Result<PipelineData, ShellError> {
+        Err(ShellError::DeprecatedCommand(
+            self.name().to_string(),
+            "math <subcommands>".to_string(),
+            call.head,
+        ))
+    }
+}

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

@@ -1,5 +1,6 @@
 mod deprecated_commands;
 mod hash_base64;
+mod math_eval;
 mod source;
 mod str_datetime;
 mod str_decimal;
@@ -8,6 +9,7 @@ mod str_int;
 
 pub use deprecated_commands::*;
 pub use hash_base64::HashBase64;
+pub use math_eval::SubCommand as MathEvalDeprecated;
 pub use source::Source;
 pub use str_datetime::StrDatetimeDeprecated;
 pub use str_decimal::StrDecimalDeprecated;

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

@@ -1,115 +0,0 @@
-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 eval"
-    }
-
-    fn usage(&self) -> &str {
-        "Evaluate a math expression into a number"
-    }
-
-    fn search_terms(&self) -> Vec<&str> {
-        vec!["evaluation", "solve", "equation", "expression"]
-    }
-
-    fn signature(&self) -> Signature {
-        Signature::build("math eval")
-            .input_output_types(vec![(Type::String, Type::Number)])
-            .optional(
-                "math expression",
-                SyntaxShape::String,
-                "the math expression to evaluate",
-            )
-            .category(Category::Math)
-    }
-
-    fn run(
-        &self,
-        engine_state: &EngineState,
-        stack: &mut Stack,
-        call: &Call,
-        input: PipelineData,
-    ) -> Result<PipelineData, ShellError> {
-        let spanned_expr: Option<Spanned<String>> = call.opt(engine_state, stack, 0)?;
-        eval(spanned_expr, input, engine_state, call.head)
-    }
-
-    fn examples(&self) -> Vec<Example> {
-        vec![Example {
-            description: "Evaluate math in the pipeline",
-            example: "'10 / 4' | math eval",
-            result: Some(Value::test_float(2.5)),
-        }]
-    }
-}
-
-pub fn eval(
-    spanned_expr: Option<Spanned<String>>,
-    input: PipelineData,
-    engine_state: &EngineState,
-    head: Span,
-) -> Result<PipelineData, ShellError> {
-    if let Some(expr) = spanned_expr {
-        match parse(&expr.item, &expr.span) {
-            Ok(value) => Ok(PipelineData::Value(value, None)),
-            Err(err) => Err(ShellError::UnsupportedInput(
-                format!("Math evaluation error: {}", err),
-                "value originates from here".into(),
-                head,
-                expr.span,
-            )),
-        }
-    } else {
-        if let PipelineData::Value(Value::Nothing { .. }, ..) = input {
-            return Ok(input);
-        }
-        input.map(
-            move |val| match val.as_string() {
-                Ok(string) => match parse(&string, &val.span().unwrap_or(head)) {
-                    Ok(value) => value,
-                    Err(err) => Value::Error {
-                        error: ShellError::UnsupportedInput(
-                            format!("Math evaluation error: {}", err),
-                            "value originates from here".into(),
-                            head,
-                            val.expect_span(),
-                        ),
-                    },
-                },
-                Err(error) => Value::Error { error },
-            },
-            engine_state.ctrlc.clone(),
-        )
-    }
-}
-
-pub fn parse(math_expression: &str, span: &Span) -> Result<Value, String> {
-    let mut ctx = meval::Context::new();
-    ctx.var("tau", std::f64::consts::TAU);
-    match meval::eval_str_with_context(math_expression, &ctx) {
-        Ok(num) if num.is_infinite() || num.is_nan() => Err("cannot represent result".to_string()),
-        Ok(num) => Ok(Value::float(num, *span)),
-        Err(error) => Err(error.to_string().to_lowercase()),
-    }
-}
-
-#[cfg(test)]
-mod test {
-    use super::*;
-
-    #[test]
-    fn test_examples() {
-        use crate::test_examples;
-
-        test_examples(SubCommand {})
-    }
-}

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

@@ -10,7 +10,6 @@ mod ceil;
 mod cos;
 mod cosh;
 mod euler;
-mod eval;
 mod floor;
 mod ln;
 mod log;
@@ -37,7 +36,6 @@ mod variance;
 pub use abs::SubCommand as MathAbs;
 pub use avg::SubCommand as MathAvg;
 pub use ceil::SubCommand as MathCeil;
-pub use eval::SubCommand as MathEval;
 pub use floor::SubCommand as MathFloor;
 pub use math_::MathCommand as Math;
 pub use max::SubCommand as MathMax;

crates/nu-command/tests/commands/math/eval.rs

@@ -1,85 +0,0 @@
-use nu_test_support::{nu, pipeline};
-
-#[test]
-fn evaluates_two_plus_two() {
-    let actual = nu!(
-        cwd: ".", pipeline(
-        r#"
-        math eval "2 + 2"
-        "#
-    ));
-
-    assert!(actual.out.contains('4'));
-}
-
-#[test]
-fn evaluates_two_to_the_power_four() {
-    let actual = nu!(
-        cwd: ".", pipeline(
-        r#"
-        echo "2 ^ 4" | math eval
-        "#
-    ));
-
-    assert!(actual.out.contains("16"));
-}
-
-#[test]
-fn evaluates_three_multiplied_by_five() {
-    let actual = nu!(
-        cwd: ".", pipeline(
-        r#"
-        echo "3 * 5" | math eval
-        "#
-    ));
-
-    assert!(actual.out.contains("15"));
-}
-
-#[test]
-fn evaluates_twenty_four_divided_by_two() {
-    let actual = nu!(
-        cwd: ".", pipeline(
-        r#"
-        echo "24 / 2" | math eval
-        "#
-    ));
-
-    assert!(actual.out.contains("12"));
-}
-
-#[test]
-fn evaluates_twenty_eight_minus_seven() {
-    let actual = nu!(
-        cwd: ".", pipeline(
-        r#"
-        echo "28 - 7" | math eval
-        "#
-    ));
-
-    assert!(actual.out.contains("21"));
-}
-
-#[test]
-fn evaluates_pi() {
-    let actual = nu!(
-        cwd: ".", pipeline(
-        r#"
-        math eval pi
-        "#
-    ));
-
-    assert!(actual.out.contains("3.14"));
-}
-
-#[test]
-fn evaluates_tau() {
-    let actual = nu!(
-        cwd: ".", pipeline(
-        r#"
-        math eval tau
-        "#
-    ));
-
-    assert!(actual.out.contains("6.28"));
-}

crates/nu-command/tests/commands/math/mod.rs

@@ -1,5 +1,4 @@
 mod avg;
-mod eval;
 mod median;
 mod round;
 mod sqrt;

crates/nu-command/tests/commands/reduce.rs

@@ -8,7 +8,7 @@ fn reduce_table_column() {
         echo "[{month:2,total:30}, {month:3,total:10}, {month:4,total:3}, {month:5,total:60}]"
         | from json
         | get total
-        | reduce -f 20 { |it, acc| $it + (math eval $"($acc)^1.05")}
+        | reduce -f 20 { |it, acc| $it + $acc ** 1.05}
         | into string -d 1
         "#
         )
@@ -23,7 +23,7 @@ fn reduce_table_column_with_path() {
         cwd: ".", pipeline(
         r#"
         [{month:2,total:30}, {month:3,total:10}, {month:4,total:3}, {month:5,total:60}]
-        | reduce -f 20 { |it, acc| $it.total + (math eval $"($acc)^1.05")}
+        | reduce -f 20 { |it, acc| $it.total + $acc ** 1.05}
         | into string -d 1
         "#
         )

crates/nu-command/tests/commands/str_/collect.rs

@@ -38,16 +38,3 @@ fn construct_a_path() {
 
     assert_eq!(actual.out, "sample.txt");
 }
-
-#[test]
-fn sum_one_to_four() {
-    let actual = nu!(
-        cwd: ".", pipeline(
-        r#"
-        1..4 | each { |it| $it } | into string | str join "+" | math eval
-        "#
-        )
-    );
-
-    assert!(actual.out.contains("10"));
-}