Stdout/Stderr redirection (#7185)

This adds new pipeline connectors called out> and err> which redirect either stdout or stderr to a file. You can also use out+err> (or err+out>) to redirect both streams into a file.

crates/nu-protocol/src/ast/pipeline.rs

@@ -2,38 +2,50 @@ use std::ops::{Index, IndexMut};
 
 use crate::{ast::Expression, engine::StateWorkingSet, Span, VarId};
 
+#[derive(Debug, Clone)]
+pub enum Redirection {
+    Stdout,
+    Stderr,
+    StdoutAndStderr,
+}
+
+// Note: Span in the below is for the span of the connector not the whole element
 #[derive(Debug, Clone)]
 pub enum PipelineElement {
-    Expression(Expression),
-    Redirect(Expression),
-    And(Expression),
-    Or(Expression),
+    Expression(Option<Span>, Expression),
+    Redirection(Span, Redirection, Expression),
+    And(Span, Expression),
+    Or(Span, Expression),
 }
 
 impl PipelineElement {
     pub fn span(&self) -> Span {
         match self {
-            PipelineElement::Expression(expression)
-            | PipelineElement::Redirect(expression)
-            | PipelineElement::And(expression)
-            | PipelineElement::Or(expression) => expression.span,
+            PipelineElement::Expression(None, expression) => expression.span,
+            PipelineElement::Expression(Some(span), expression)
+            | PipelineElement::Redirection(span, _, expression)
+            | PipelineElement::And(span, expression)
+            | PipelineElement::Or(span, expression) => Span {
+                start: span.start,
+                end: expression.span.end,
+            },
         }
     }
     pub fn has_in_variable(&self, working_set: &StateWorkingSet) -> bool {
         match self {
-            PipelineElement::Expression(expression)
-            | PipelineElement::Redirect(expression)
-            | PipelineElement::And(expression)
-            | PipelineElement::Or(expression) => expression.has_in_variable(working_set),
+            PipelineElement::Expression(_, expression)
+            | PipelineElement::Redirection(_, _, expression)
+            | PipelineElement::And(_, expression)
+            | PipelineElement::Or(_, expression) => expression.has_in_variable(working_set),
         }
     }
 
     pub fn replace_in_variable(&mut self, working_set: &mut StateWorkingSet, new_var_id: VarId) {
         match self {
-            PipelineElement::Expression(expression)
-            | PipelineElement::Redirect(expression)
-            | PipelineElement::And(expression)
-            | PipelineElement::Or(expression) => {
+            PipelineElement::Expression(_, expression)
+            | PipelineElement::Redirection(_, _, expression)
+            | PipelineElement::And(_, expression)
+            | PipelineElement::Or(_, expression) => {
                 expression.replace_in_variable(working_set, new_var_id)
             }
         }
@@ -46,10 +58,10 @@ impl PipelineElement {
         new_span: Span,
     ) {
         match self {
-            PipelineElement::Expression(expression)
-            | PipelineElement::Redirect(expression)
-            | PipelineElement::And(expression)
-            | PipelineElement::Or(expression) => {
+            PipelineElement::Expression(_, expression)
+            | PipelineElement::Redirection(_, _, expression)
+            | PipelineElement::And(_, expression)
+            | PipelineElement::Or(_, expression) => {
                 expression.replace_span(working_set, replaced, new_span)
             }
         }
@@ -76,7 +88,10 @@ impl Pipeline {
         Self {
             elements: expressions
                 .into_iter()
-                .map(PipelineElement::Expression)
+                .enumerate()
+                .map(|(idx, x)| {
+                    PipelineElement::Expression(if idx == 0 { None } else { Some(x.span) }, x)
+                })
                 .collect(),
         }
     }

crates/nu-protocol/src/value/stream.rs

@@ -53,6 +53,20 @@ impl RawStream {
 
         Ok(Spanned { item: output, span })
     }
+
+    pub fn chain(self, stream: RawStream) -> RawStream {
+        RawStream {
+            stream: Box::new(self.stream.chain(stream.stream)),
+            leftover: self
+                .leftover
+                .into_iter()
+                .chain(stream.leftover.into_iter())
+                .collect(),
+            ctrlc: self.ctrlc,
+            is_binary: self.is_binary,
+            span: self.span,
+        }
+    }
 }
 impl Debug for RawStream {
     fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {