"merging into one dfr into-nu command" (#9858)

- fixes #9806

# Description

Merges ExprAsNu command and ToNu into one command. 

# User-Facing Changes

As both commands were overloading ```dfr into-nu``` there are no user
facing changes

---------

Co-authored-by: Jack Wright <jack.wright@disqo.com>

crates/nu-cmd-dataframe/src/dataframe/eager/to_nu.rs

@@ -5,6 +5,8 @@ use nu_protocol::{
     Category, Example, PipelineData, ShellError, Signature, Span, SyntaxShape, Type, Value,
 };
 
+use crate::dataframe::values::NuExpression;
+
 use super::super::values::NuDataFrame;
 
 #[derive(Clone)]
@@ -16,7 +18,7 @@ impl Command for ToNu {
     }
 
     fn usage(&self) -> &str {
-        "Converts a section of the dataframe into nushell Table."
+        "Converts a dataframe or an expression into into nushell value for access and exploration."
     }
 
     fn signature(&self) -> Signature {
@@ -28,7 +30,11 @@ impl Command for ToNu {
                 Some('n'),
             )
             .switch("tail", "shows tail rows", Some('t'))
-            .input_output_type(Type::Custom("dataframe".into()), Type::Any)
+            .input_output_types(vec![
+                (Type::Custom("expression".into()), Type::Any),
+                (Type::Custom("dataframe".into()), Type::Table(vec![])),
+            ])
+            //.input_output_type(Type::Any, Type::Any)
             .category(Category::Custom("dataframe".into()))
     }
 
@@ -67,6 +73,15 @@ impl Command for ToNu {
                     span: Span::test_data(),
                 }),
             },
+            Example {
+                description: "Convert a col expression into a nushell value",
+                example: "dfr col a | dfr into-nu",
+                result: Some(Value::Record {
+                    cols: vec!["expr".into(), "value".into()],
+                    vals: vec![Value::test_string("column"), Value::test_string("a")],
+                    span: Span::test_data(),
+                }),
+            },
         ]
     }
 
@@ -77,20 +92,25 @@ impl Command for ToNu {
         call: &Call,
         input: PipelineData,
     ) -> Result<PipelineData, ShellError> {
-        command(engine_state, stack, call, input)
+        let value = input.into_value(call.head);
+        if NuDataFrame::can_downcast(&value) {
+            dataframe_command(engine_state, stack, call, value)
+        } else {
+            expression_command(call, value)
+        }
     }
 }
 
-fn command(
+fn dataframe_command(
     engine_state: &EngineState,
     stack: &mut Stack,
     call: &Call,
-    input: PipelineData,
+    input: Value,
 ) -> Result<PipelineData, ShellError> {
     let rows: Option<usize> = call.get_flag(engine_state, stack, "rows")?;
     let tail: bool = call.has_flag("tail");
 
-    let df = NuDataFrame::try_from_pipeline(input, call.head)?;
+    let df = NuDataFrame::try_from_value(input)?;
 
     let values = if tail {
         df.tail(rows, call.head)?
@@ -110,14 +130,26 @@ fn command(
 
     Ok(PipelineData::Value(value, None))
 }
+fn expression_command(call: &Call, input: Value) -> Result<PipelineData, ShellError> {
+    let expr = NuExpression::try_from_value(input)?;
+    let value = expr.to_value(call.head);
+
+    Ok(PipelineData::Value(value, None))
+}
 
 #[cfg(test)]
 mod test {
+    use super::super::super::expressions::ExprCol;
     use super::super::super::test_dataframe::test_dataframe;
     use super::*;
 
     #[test]
-    fn test_examples() {
+    fn test_examples_dataframe_input() {
         test_dataframe(vec![Box::new(ToNu {})])
     }
+
+    #[test]
+    fn test_examples_expression_input() {
+        test_dataframe(vec![Box::new(ToNu {}), Box::new(ExprCol {})])
+    }
 }

crates/nu-cmd-dataframe/src/dataframe/expressions/alias.rs

@@ -88,7 +88,7 @@ impl Command for ExprAlias {
 mod test {
     use super::super::super::test_dataframe::test_dataframe;
     use super::*;
-    use crate::dataframe::expressions::ExprAsNu;
+    use crate::dataframe::eager::ToNu;
     use crate::dataframe::expressions::ExprCol;
 
     #[test]
@@ -96,7 +96,7 @@ mod test {
         test_dataframe(vec![
             Box::new(ExprAlias {}),
             Box::new(ExprCol {}),
-            Box::new(ExprAsNu {}),
+            Box::new(ToNu {}),
         ])
     }
 }

crates/nu-cmd-dataframe/src/dataframe/expressions/as_nu.rs

@@ -1,67 +0,0 @@
-use super::super::values::NuExpression;
-
-use nu_protocol::{
-    ast::Call,
-    engine::{Command, EngineState, Stack},
-    Category, Example, PipelineData, ShellError, Signature, Span, Type, Value,
-};
-
-#[derive(Clone)]
-pub struct ExprAsNu;
-
-impl Command for ExprAsNu {
-    fn name(&self) -> &str {
-        "dfr into-nu"
-    }
-
-    fn usage(&self) -> &str {
-        "Convert expression into a nu value for access and exploration."
-    }
-
-    fn signature(&self) -> Signature {
-        Signature::build(self.name())
-            .input_output_type(Type::Custom("expression".into()), Type::Any)
-            .category(Category::Custom("expression".into()))
-    }
-
-    fn examples(&self) -> Vec<Example> {
-        vec![Example {
-            description: "Convert a col expression into a nushell value",
-            example: "dfr col a | dfr into-nu",
-            result: Some(Value::Record {
-                cols: vec!["expr".into(), "value".into()],
-                vals: vec![Value::test_string("column"), Value::test_string("a")],
-                span: Span::test_data(),
-            }),
-        }]
-    }
-
-    fn search_terms(&self) -> Vec<&str> {
-        vec!["convert", "conversion"]
-    }
-
-    fn run(
-        &self,
-        _engine_state: &EngineState,
-        _stack: &mut Stack,
-        call: &Call,
-        input: PipelineData,
-    ) -> Result<PipelineData, ShellError> {
-        let expr = NuExpression::try_from_pipeline(input, call.head)?;
-        let value = expr.to_value(call.head);
-
-        Ok(PipelineData::Value(value, None))
-    }
-}
-
-#[cfg(test)]
-mod test {
-    use super::super::super::test_dataframe::test_dataframe;
-    use super::super::ExprCol;
-    use super::*;
-
-    #[test]
-    fn test_examples() {
-        test_dataframe(vec![Box::new(ExprAsNu {}), Box::new(ExprCol {})])
-    }
-}

crates/nu-cmd-dataframe/src/dataframe/expressions/col.rs

@@ -64,10 +64,10 @@ impl Command for ExprCol {
 mod test {
     use super::super::super::test_dataframe::test_dataframe;
     use super::*;
-    use crate::dataframe::expressions::as_nu::ExprAsNu;
+    use crate::dataframe::eager::ToNu;
 
     #[test]
     fn test_examples() {
-        test_dataframe(vec![Box::new(ExprCol {}), Box::new(ExprAsNu {})])
+        test_dataframe(vec![Box::new(ExprCol {}), Box::new(ToNu {})])
     }
 }

crates/nu-cmd-dataframe/src/dataframe/expressions/datepart.rs

@@ -144,9 +144,9 @@ impl Command for ExprDatePart {
 mod test {
     use super::super::super::test_dataframe::test_dataframe;
     use super::*;
+    use crate::dataframe::eager::ToNu;
     use crate::dataframe::eager::WithColumn;
     use crate::dataframe::expressions::ExprAlias;
-    use crate::dataframe::expressions::ExprAsNu;
     use crate::dataframe::expressions::ExprCol;
     use crate::dataframe::series::AsDateTime;
 
@@ -155,7 +155,7 @@ mod test {
         test_dataframe(vec![
             Box::new(ExprDatePart {}),
             Box::new(ExprCol {}),
-            Box::new(ExprAsNu {}),
+            Box::new(ToNu {}),
             Box::new(AsDateTime {}),
             Box::new(WithColumn {}),
             Box::new(ExprAlias {}),

crates/nu-cmd-dataframe/src/dataframe/expressions/lit.rs

@@ -66,10 +66,10 @@ impl Command for ExprLit {
 mod test {
     use super::super::super::test_dataframe::test_dataframe;
     use super::*;
-    use crate::dataframe::expressions::as_nu::ExprAsNu;
+    use crate::dataframe::eager::ToNu;
 
     #[test]
     fn test_examples() {
-        test_dataframe(vec![Box::new(ExprLit {}), Box::new(ExprAsNu {})])
+        test_dataframe(vec![Box::new(ExprLit {}), Box::new(ToNu {})])
     }
 }

crates/nu-cmd-dataframe/src/dataframe/expressions/mod.rs

@@ -1,6 +1,5 @@
 mod alias;
 mod arg_where;
-mod as_nu;
 mod col;
 mod concat_str;
 mod datepart;
@@ -15,7 +14,6 @@ use nu_protocol::engine::StateWorkingSet;
 
 pub(crate) use crate::dataframe::expressions::alias::ExprAlias;
 use crate::dataframe::expressions::arg_where::ExprArgWhere;
-use crate::dataframe::expressions::as_nu::ExprAsNu;
 pub(super) use crate::dataframe::expressions::col::ExprCol;
 pub(super) use crate::dataframe::expressions::concat_str::ExprConcatStr;
 pub(crate) use crate::dataframe::expressions::datepart::ExprDatePart;
@@ -44,7 +42,6 @@ pub fn add_expressions(working_set: &mut StateWorkingSet) {
         ExprConcatStr,
         ExprCount,
         ExprLit,
-        ExprAsNu,
         ExprWhen,
         ExprOtherwise,
         ExprQuantile,

crates/nu-cmd-dataframe/src/dataframe/expressions/otherwise.rs

@@ -110,9 +110,9 @@ impl Command for ExprOtherwise {
 #[cfg(test)]
 mod test {
     use super::super::super::test_dataframe::test_dataframe;
-    use crate::dataframe::eager::WithColumn;
+    use crate::dataframe::eager::{ToNu, WithColumn};
     use crate::dataframe::expressions::when::ExprWhen;
-    use crate::dataframe::expressions::{ExprAlias, ExprAsNu, ExprCol};
+    use crate::dataframe::expressions::{ExprAlias, ExprCol};
 
     use super::*;
 
@@ -124,7 +124,7 @@ mod test {
             Box::new(ExprAlias {}),
             Box::new(ExprWhen {}),
             Box::new(ExprOtherwise {}),
-            Box::new(ExprAsNu {}),
+            Box::new(ToNu {}),
         ])
     }
 }

crates/nu-cmd-dataframe/src/dataframe/expressions/when.rs

@@ -128,9 +128,9 @@ impl Command for ExprWhen {
 #[cfg(test)]
 mod test {
     use super::super::super::test_dataframe::test_dataframe;
-    use crate::dataframe::eager::WithColumn;
+    use crate::dataframe::eager::{ToNu, WithColumn};
     use crate::dataframe::expressions::otherwise::ExprOtherwise;
-    use crate::dataframe::expressions::{ExprAlias, ExprAsNu, ExprCol};
+    use crate::dataframe::expressions::{ExprAlias, ExprCol};
 
     use super::*;
 
@@ -142,7 +142,7 @@ mod test {
             Box::new(ExprAlias {}),
             Box::new(ExprWhen {}),
             Box::new(ExprOtherwise {}),
-            Box::new(ExprAsNu {}),
+            Box::new(ToNu {}),
         ])
     }
 }