Fix the for loop to create vars

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

@@ -2,6 +2,7 @@ mod alias;
 mod def;
 mod do_;
 mod export_def;
+mod for_;
 mod help;
 mod hide;
 mod if_;
@@ -14,6 +15,7 @@ pub use alias::Alias;
 pub use def::Def;
 pub use do_::Do;
 pub use export_def::ExportDef;
+pub use for_::For;
 pub use help::Help;
 pub use hide::Hide;
 pub use if_::If;

crates/nu-command/src/filters/for_.rs

@@ -1,132 +0,0 @@
-use nu_engine::{eval_block, eval_expression};
-use nu_protocol::ast::Call;
-use nu_protocol::engine::{Command, EvaluationContext};
-use nu_protocol::{Example, IntoValueStream, Signature, Span, SyntaxShape, Value};
-
-pub struct For;
-
-impl Command for For {
-    fn name(&self) -> &str {
-        "for"
-    }
-
-    fn usage(&self) -> &str {
-        "Loop over a range"
-    }
-
-    fn signature(&self) -> nu_protocol::Signature {
-        Signature::build("for")
-            .required(
-                "var_name",
-                SyntaxShape::Variable,
-                "name of the looping variable",
-            )
-            .required(
-                "range",
-                SyntaxShape::Keyword(
-                    b"in".to_vec(),
-                    Box::new(SyntaxShape::List(Box::new(SyntaxShape::Int))),
-                ),
-                "range of the loop",
-            )
-            .required(
-                "block",
-                SyntaxShape::Block(Some(vec![])),
-                "the block to run",
-            )
-    }
-
-    fn run(
-        &self,
-        context: &EvaluationContext,
-        call: &Call,
-        _input: Value,
-    ) -> Result<nu_protocol::Value, nu_protocol::ShellError> {
-        let var_id = call.positional[0]
-            .as_var()
-            .expect("internal error: missing variable");
-
-        let keyword_expr = call.positional[1]
-            .as_keyword()
-            .expect("internal error: missing keyword");
-        let values = eval_expression(context, keyword_expr)?;
-
-        let block = call.positional[2]
-            .as_block()
-            .expect("internal error: expected block");
-        let context = context.clone();
-
-        match values {
-            Value::Stream { stream, .. } => Ok(Value::Stream {
-                stream: stream
-                    .map(move |x| {
-                        let engine_state = context.engine_state.borrow();
-                        let block = engine_state.get_block(block);
-
-                        let state = context.enter_scope();
-                        state.add_var(var_id, x);
-
-                        //FIXME: DON'T UNWRAP
-                        eval_block(&state, block, Value::nothing()).unwrap()
-                    })
-                    .into_value_stream(),
-                span: call.head,
-            }),
-            Value::List { vals: val, .. } => Ok(Value::List {
-                vals: val
-                    .into_iter()
-                    .map(move |x| {
-                        let engine_state = context.engine_state.borrow();
-                        let block = engine_state.get_block(block);
-
-                        let state = context.enter_scope();
-                        state.add_var(var_id, x);
-
-                        //FIXME: DON'T UNWRAP
-                        eval_block(&state, block, Value::nothing()).unwrap()
-                    })
-                    .collect(),
-                span: call.head,
-            }),
-            _ => Ok(Value::nothing()),
-        }
-    }
-
-    fn examples(&self) -> Vec<Example> {
-        let span = Span::unknown();
-        vec![
-            Example {
-                description: "Echo the square of each integer",
-                example: "for x in [1 2 3] { $x * $x }",
-                result: Some(vec![
-                    Value::Int { val: 1, span },
-                    Value::Int { val: 4, span },
-                    Value::Int { val: 9, span },
-                ]),
-            },
-            Example {
-                description: "Work with elements of a range",
-                example: "for $x in 1..3 { $x }",
-                result: Some(vec![
-                    Value::Int { val: 1, span },
-                    Value::Int { val: 2, span },
-                    Value::Int { val: 3, span },
-                ]),
-            },
-            Example {
-                description: "Number each item and echo a message",
-                example: "for $it in ['bob' 'fred'] --numbered { $\"($it.index) is ($it.item)\" }",
-                result: Some(vec![
-                    Value::String {
-                        val: "0 is bob".into(),
-                        span,
-                    },
-                    Value::String {
-                        val: "0 is fred".into(),
-                        span,
-                    },
-                ]),
-            },
-        ]
-    }
-}

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

@@ -1,5 +1,4 @@
 mod each;
-mod for_;
 mod get;
 mod length;
 mod lines;
@@ -8,7 +7,6 @@ mod where_;
 mod wrap;
 
 pub use each::Each;
-pub use for_::For;
 pub use get::Get;
 pub use length::Length;
 pub use lines::Lines;

crates/nu-parser/src/parser.rs

@@ -459,6 +459,10 @@ pub fn parse_internal_call(
 
     let signature = working_set.get_decl(decl_id).signature();
 
+    if signature.creates_scope {
+        working_set.enter_scope();
+    }
+
     // The index into the positional parameter in the definition
     let mut positional_idx = 0;
 
@@ -554,6 +558,10 @@ pub fn parse_internal_call(
     let err = check_call(command_span, &signature, &call);
     error = error.or(err);
 
+    if signature.creates_scope {
+        working_set.exit_scope();
+    }
+
     // FIXME: type unknown
     (Box::new(call), span(spans), error)
 }

crates/nu-protocol/src/signature.rs

@@ -36,6 +36,7 @@ pub struct Signature {
     pub rest_positional: Option<PositionalArg>,
     pub named: Vec<Flag>,
     pub is_filter: bool,
+    pub creates_scope: bool,
 }
 
 impl PartialEq for Signature {
@@ -62,6 +63,7 @@ impl Signature {
             rest_positional: None,
             named: vec![],
             is_filter: false,
+            creates_scope: false,
         }
     }
     pub fn build(name: impl Into<String>) -> Signature {
@@ -189,6 +191,12 @@ impl Signature {
         self
     }
 
+    /// Sets that signature will create a scope as it parses
+    pub fn creates_scope(mut self) -> Signature {
+        self.creates_scope = true;
+        self
+    }
+
     /// Get list of the short-hand flags
     pub fn get_shorts(&self) -> Vec<char> {
         self.named.iter().filter_map(|f| f.short).collect()

src/tests.rs

@@ -553,3 +553,8 @@ fn split_column() -> TestResult {
         "hello",
     )
 }
+
+#[test]
+fn for_loops() -> TestResult {
+    run_test(r#"(for x in [1, 2, 3] { $x + 10 }).1"#, "12")
+}