From e3da546e23f6eeda84fbc81ba287920390df32e0 Mon Sep 17 00:00:00 2001
From: Jonathan Turner <jonathandturner@users.noreply.github.com>
Date: Mon, 21 Dec 2020 16:02:39 +1300
Subject: [PATCH] Simplifies 'if' to work on the available scope rather than a
 stream (#2805)

---
 crates/nu-cli/src/commands/if_.rs | 70 +++++++++----------------------
 crates/nu-cli/src/examples.rs     |  5 ++-
 tests/shell/mod.rs                |  2 +-
 3 files changed, 25 insertions(+), 52 deletions(-)

diff --git a/crates/nu-cli/src/commands/if_.rs b/crates/nu-cli/src/commands/if_.rs
index f63e83708..dddd2bee3 100644
--- a/crates/nu-cli/src/commands/if_.rs
+++ b/crates/nu-cli/src/commands/if_.rs
@@ -53,12 +53,12 @@ impl WholeStreamCommand for If {
         vec![
             Example {
                 description: "Run a block if a condition is true",
-                example: "echo 10 | if $it > 5 { echo 'greater than 5' } { echo 'less than or equal to 5' }",
+                example: "set x = 10; if $x > 5 { echo 'greater than 5' } { echo 'less than or equal to 5' }",
                 result: Some(vec![UntaggedValue::string("greater than 5").into()]),
             },
             Example {
                 description: "Run a block if a condition is false",
-                example: "echo 1 | if $it > 5 { echo 'greater than 5' } { echo 'less than or equal to 5' }",
+                example: "set x = 1; if $x > 5 { echo 'greater than 5' } { echo 'less than or equal to 5' }",
                 result: Some(vec![UntaggedValue::string("less than or equal to 5").into()]),
             },
         ]
@@ -105,57 +105,27 @@ async fn if_command(raw_args: CommandArgs) -> Result<OutputStream, ShellError> {
         }
     };
 
-    Ok(input
-        .then(move |input| {
-            let cond = cond.clone();
-            let then_case = then_case.clone();
-            let else_case = else_case.clone();
-            let context = context.clone();
-            context.scope.enter_scope();
-            context.scope.add_vars(&condition.captured.entries);
-            context.scope.add_var("$it", input);
+    context.scope.enter_scope();
+    context.scope.add_vars(&condition.captured.entries);
 
-            async move {
-                //FIXME: should we use the scope that's brought in as well?
-                let condition = evaluate_baseline_expr(&cond, &*context).await;
+    //FIXME: should we use the scope that's brought in as well?
+    let condition = evaluate_baseline_expr(&cond, &*context).await;
+    match condition {
+        Ok(condition) => match condition.as_bool() {
+            Ok(b) => {
+                let result = if b {
+                    run_block(&then_case.block, &*context, input).await
+                } else {
+                    run_block(&else_case.block, &*context, input).await
+                };
+                context.scope.exit_scope();
 
-                match condition {
-                    Ok(condition) => match condition.as_bool() {
-                        Ok(b) => {
-                            if b {
-                                let result =
-                                    run_block(&then_case.block, &*context, InputStream::empty())
-                                        .await;
-                                context.scope.exit_scope();
-
-                                match result {
-                                    Ok(stream) => stream.to_output_stream(),
-                                    Err(e) => futures::stream::iter(vec![Err(e)].into_iter())
-                                        .to_output_stream(),
-                                }
-                            } else {
-                                let result =
-                                    run_block(&else_case.block, &*context, InputStream::empty())
-                                        .await;
-                                context.scope.exit_scope();
-
-                                match result {
-                                    Ok(stream) => stream.to_output_stream(),
-                                    Err(e) => futures::stream::iter(vec![Err(e)].into_iter())
-                                        .to_output_stream(),
-                                }
-                            }
-                        }
-                        Err(e) => {
-                            futures::stream::iter(vec![Err(e)].into_iter()).to_output_stream()
-                        }
-                    },
-                    Err(e) => futures::stream::iter(vec![Err(e)].into_iter()).to_output_stream(),
-                }
+                result.map(|x| x.to_output_stream())
             }
-        })
-        .flatten()
-        .to_output_stream())
+            Err(e) => Ok(futures::stream::iter(vec![Err(e)].into_iter()).to_output_stream()),
+        },
+        Err(e) => Ok(futures::stream::iter(vec![Err(e)].into_iter()).to_output_stream()),
+    }
 }
 
 #[cfg(test)]
diff --git a/crates/nu-cli/src/examples.rs b/crates/nu-cli/src/examples.rs
index 28ce79378..8c734d709 100644
--- a/crates/nu-cli/src/examples.rs
+++ b/crates/nu-cli/src/examples.rs
@@ -13,7 +13,7 @@ use num_bigint::BigInt;
 use crate::commands::classified::block::run_block;
 use crate::commands::command::CommandArgs;
 use crate::commands::{
-    whole_stream_command, BuildString, Command, Each, Echo, First, Get, Keep, Last, Nth,
+    whole_stream_command, BuildString, Command, Each, Echo, First, Get, Keep, Last, Nth, Set,
     StrCollect, WholeStreamCommand, Wrap,
 };
 use crate::evaluation_context::EvaluationContext;
@@ -40,6 +40,7 @@ pub fn test_examples(cmd: Command) -> Result<(), ShellError> {
         whole_stream_command(Each {}),
         whole_stream_command(Last {}),
         whole_stream_command(Nth {}),
+        whole_stream_command(Set {}),
         whole_stream_command(StrCollect),
         whole_stream_command(Wrap),
         cmd,
@@ -97,6 +98,7 @@ pub fn test(cmd: impl WholeStreamCommand + 'static) -> Result<(), ShellError> {
         whole_stream_command(Get {}),
         whole_stream_command(Keep {}),
         whole_stream_command(Each {}),
+        whole_stream_command(Set {}),
         whole_stream_command(cmd),
         whole_stream_command(StrCollect),
         whole_stream_command(Wrap),
@@ -158,6 +160,7 @@ pub fn test_anchors(cmd: Command) -> Result<(), ShellError> {
         whole_stream_command(Each {}),
         whole_stream_command(Last {}),
         whole_stream_command(Nth {}),
+        whole_stream_command(Set {}),
         whole_stream_command(StrCollect),
         whole_stream_command(Wrap),
         cmd,
diff --git a/tests/shell/mod.rs b/tests/shell/mod.rs
index 1e2d60142..87fd0abed 100644
--- a/tests/shell/mod.rs
+++ b/tests/shell/mod.rs
@@ -27,7 +27,7 @@ fn plugins_are_declared_with_wix() {
                 | wrap wix
             }
             | default wix _
-            | if $it.wix != $it.cargo { = 1 } { = 0 }
+            | each { if $it.wix != $it.cargo { = 1 } { = 0 } }
             | math sum
             "#
     ));