Merge pull request #129 from nushell/do_rest_args

Do rest args

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

@@ -1,4 +1,4 @@
-use nu_engine::{eval_block, eval_expression};
+use nu_engine::{eval_block, CallExt};
 use nu_protocol::ast::Call;
 use nu_protocol::engine::{Command, EvaluationContext};
 use nu_protocol::{Signature, SyntaxShape, Value};
@@ -15,11 +15,14 @@ impl Command for Do {
     }
 
     fn signature(&self) -> nu_protocol::Signature {
-        Signature::build("do").desc(self.usage()).required(
-            "block",
-            SyntaxShape::Block(Some(vec![])),
-            "the block to run",
-        )
+        Signature::build("do")
+            .desc(self.usage())
+            .required(
+                "block",
+                SyntaxShape::Block(Some(vec![])),
+                "the block to run",
+            )
+            .rest("rest", SyntaxShape::Any, "the parameter(s) for the block")
     }
 
     fn run(
@@ -28,17 +31,54 @@ impl Command for Do {
         call: &Call,
         input: Value,
     ) -> Result<nu_protocol::Value, nu_protocol::ShellError> {
-        let block = &call.positional[0];
+        let block_id = call.positional[0]
+            .as_block()
+            .expect("internal error: expected block");
+        let rest: Vec<Value> = call.rest(context, 1)?;
 
-        let out = eval_expression(context, block)?;
+        let engine_state = context.engine_state.borrow();
+        let block = engine_state.get_block(block_id);
 
-        match out {
-            Value::Block { val: block_id, .. } => {
-                let engine_state = context.engine_state.borrow();
-                let block = engine_state.get_block(block_id);
-                eval_block(context, block, input)
+        let state = context.enter_scope();
+
+        let params: Vec<_> = block
+            .signature
+            .required_positional
+            .iter()
+            .chain(block.signature.optional_positional.iter())
+            .collect();
+
+        for param in params.iter().zip(&rest) {
+            if let Some(var_id) = param.0.var_id {
+                state.add_var(var_id, param.1.clone())
             }
-            _ => Ok(Value::nothing()),
         }
+
+        if let Some(param) = &block.signature.rest_positional {
+            if rest.len() > params.len() {
+                let mut rest_items = vec![];
+
+                for r in rest.into_iter().skip(params.len()) {
+                    rest_items.push(r);
+                }
+
+                let span = if let Some(rest_item) = rest_items.first() {
+                    rest_item.span()?
+                } else {
+                    call.head
+                };
+
+                state.add_var(
+                    param
+                        .var_id
+                        .expect("Internal error: rest positional parameter lacks var_id"),
+                    Value::List {
+                        vals: rest_items,
+                        span,
+                    },
+                )
+            }
+        }
+        eval_block(&state, block, input)
     }
 }

src/tests.rs

@@ -722,3 +722,8 @@ fn flag_param_value() -> TestResult {
         "155",
     )
 }
+
+#[test]
+fn do_rest_args() -> TestResult {
+    run_test(r#"(do { |...rest| $rest } 1 2).1 + 10"#, "12")
+}