From 979faf853adeadce00728877e0000a07f8baa972 Mon Sep 17 00:00:00 2001
From: JT <jonathan.d.turner@gmail.com>
Date: Mon, 6 Sep 2021 14:20:02 +1200
Subject: [PATCH] Block params

---
 crates/nu-cli/src/errors.rs                   |  2 +-
 crates/nu-engine/src/eval.rs                  |  2 +-
 crates/nu-parser/src/parser.rs                | 16 +++++++++++++++-
 crates/nu-protocol/src/engine/engine_state.rs | 14 ++++++++++++--
 crates/nu-protocol/src/shell_error.rs         |  2 +-
 crates/nu-protocol/src/signature.rs           |  2 +-
 src/tests.rs                                  | 10 ++++++++++
 7 files changed, 41 insertions(+), 7 deletions(-)

diff --git a/crates/nu-cli/src/errors.rs b/crates/nu-cli/src/errors.rs
index ef25181cad..d35f0c9ede 100644
--- a/crates/nu-cli/src/errors.rs
+++ b/crates/nu-cli/src/errors.rs
@@ -297,7 +297,7 @@ pub fn report_shell_error(
             ShellError::InternalError(s) => {
                 Diagnostic::error().with_message(format!("Internal error: {}", s))
             }
-            ShellError::VariableNotFound(span) => {
+            ShellError::VariableNotFoundAtRuntime(span) => {
                 let (diag_file_id, diag_range) = convert_span_to_diag(working_set, span)?;
                 Diagnostic::error()
                     .with_message("Variable not found")
diff --git a/crates/nu-engine/src/eval.rs b/crates/nu-engine/src/eval.rs
index e629ab3034..f4042816bf 100644
--- a/crates/nu-engine/src/eval.rs
+++ b/crates/nu-engine/src/eval.rs
@@ -101,7 +101,7 @@ pub fn eval_expression(
         }
         Expr::Var(var_id) => context
             .get_var(*var_id)
-            .map_err(move |_| ShellError::VariableNotFound(expr.span)),
+            .map_err(move |_| ShellError::VariableNotFoundAtRuntime(expr.span)),
         Expr::Call(call) => eval_call(context, call, Value::nothing()),
         Expr::ExternalCall(_, _) => Err(ShellError::ExternalNotSupported(expr.span)),
         Expr::Operator(_) => Ok(Value::Nothing { span: expr.span }),
diff --git a/crates/nu-parser/src/parser.rs b/crates/nu-parser/src/parser.rs
index d9206b1e0e..a3adc73974 100644
--- a/crates/nu-parser/src/parser.rs
+++ b/crates/nu-parser/src/parser.rs
@@ -1771,6 +1771,7 @@ pub fn parse_block_expression(
     let (output, err) = lex(source, start, &[], &[]);
     error = error.or(err);
 
+    working_set.enter_scope();
     // Check to see if we have parameters
     let (signature, amt_to_skip): (Option<Box<Signature>>, usize) = match output.first() {
         Some(Token {
@@ -1818,13 +1819,26 @@ pub fn parse_block_expression(
     let (output, err) = lite_parse(&output[amt_to_skip..]);
     error = error.or(err);
 
-    let (mut output, err) = parse_block(working_set, &output, true);
+    let (mut output, err) = parse_block(working_set, &output, false);
     error = error.or(err);
 
     if let Some(signature) = signature {
         output.signature = signature;
+    } else if let Some(last) = working_set.delta.scope.last() {
+        if let Some(var_id) = last.get_var(b"$it") {
+            let mut signature = Signature::new("");
+            signature.required_positional.push(PositionalArg {
+                var_id: Some(*var_id),
+                name: "$it".into(),
+                desc: String::new(),
+                shape: SyntaxShape::Any,
+            });
+            output.signature = Box::new(signature);
+        }
     }
 
+    working_set.exit_scope();
+
     let block_id = working_set.add_block(output);
 
     (
diff --git a/crates/nu-protocol/src/engine/engine_state.rs b/crates/nu-protocol/src/engine/engine_state.rs
index 31ad6b6b2a..80d437a57c 100644
--- a/crates/nu-protocol/src/engine/engine_state.rs
+++ b/crates/nu-protocol/src/engine/engine_state.rs
@@ -13,7 +13,7 @@ pub struct EngineState {
 }
 
 #[derive(Debug)]
-struct ScopeFrame {
+pub struct ScopeFrame {
     vars: HashMap<Vec<u8>, VarId>,
     decls: HashMap<Vec<u8>, DeclId>,
     aliases: HashMap<Vec<u8>, Vec<Span>>,
@@ -27,6 +27,16 @@ impl ScopeFrame {
             aliases: HashMap::new(),
         }
     }
+
+    pub fn get_var(&self, var_name: &[u8]) -> Option<&VarId> {
+        self.vars.get(var_name)
+    }
+}
+
+impl Default for ScopeFrame {
+    fn default() -> Self {
+        Self::new()
+    }
 }
 
 impl Default for EngineState {
@@ -188,7 +198,7 @@ pub struct StateDelta {
     vars: Vec<Type>,              // indexed by VarId
     decls: Vec<Box<dyn Command>>, // indexed by DeclId
     blocks: Vec<Block>,           // indexed by BlockId
-    scope: Vec<ScopeFrame>,
+    pub scope: Vec<ScopeFrame>,
 }
 
 impl StateDelta {
diff --git a/crates/nu-protocol/src/shell_error.rs b/crates/nu-protocol/src/shell_error.rs
index a769faacf8..78f672921d 100644
--- a/crates/nu-protocol/src/shell_error.rs
+++ b/crates/nu-protocol/src/shell_error.rs
@@ -13,7 +13,7 @@ pub enum ShellError {
     UnknownOperator(String, Span),
     ExternalNotSupported(Span),
     InternalError(String),
-    VariableNotFound(Span),
+    VariableNotFoundAtRuntime(Span),
     CantConvert(String, Span),
     DivisionByZero(Span),
 }
diff --git a/crates/nu-protocol/src/signature.rs b/crates/nu-protocol/src/signature.rs
index 2c12efd00b..0bf8fa0954 100644
--- a/crates/nu-protocol/src/signature.rs
+++ b/crates/nu-protocol/src/signature.rs
@@ -350,7 +350,7 @@ impl Command for BlockCommand {
     }
 
     fn signature(&self) -> Signature {
-        panic!("Internal error: can't get signature with 'signature', use block_id");
+        self.signature.clone()
     }
 
     fn usage(&self) -> &str {
diff --git a/src/tests.rs b/src/tests.rs
index 97e4630689..820af046a9 100644
--- a/src/tests.rs
+++ b/src/tests.rs
@@ -203,3 +203,13 @@ fn alias_2() -> TestResult {
         "143",
     )
 }
+
+#[test]
+fn block_param1() -> TestResult {
+    run_test("[3] | each { $it + 10 }", "13")
+}
+
+#[test]
+fn block_param2() -> TestResult {
+    run_test("[3] | each { |y| $y + 10 }", "13")
+}