From 9e7f84afb0f1cd2b5c2da7cfbf165305489e1a32 Mon Sep 17 00:00:00 2001
From: WindSoilder <WindSoilder@outlook.com>
Date: Thu, 19 Oct 2023 05:23:17 +0800
Subject: [PATCH] Refactor: simplify lex_item impl (#10744)

In the final match of `lex_item`, we'll return `Err(ParseError)` in rare
case, normally we'll return None.

So I think making error part mutable can reduce some code, and it's
better if we want to add more lex items.
---
 crates/nu-parser/src/lex.rs | 74 ++++++++++++++++---------------------
 1 file changed, 32 insertions(+), 42 deletions(-)

diff --git a/crates/nu-parser/src/lex.rs b/crates/nu-parser/src/lex.rs
index 34701efdf4..50f0909d3a 100644
--- a/crates/nu-parser/src/lex.rs
+++ b/crates/nu-parser/src/lex.rs
@@ -254,57 +254,47 @@ pub fn lex_item(
         );
     }
 
-    match &input[(span.start - span_offset)..(span.end - span_offset)] {
-        b"out>" | b"o>" => (
-            Token {
-                contents: TokenContents::OutGreaterThan,
-                span,
-            },
-            None,
-        ),
-        b"err>" | b"e>" => (
-            Token {
-                contents: TokenContents::ErrGreaterThan,
-                span,
-            },
-            None,
-        ),
-        b"out+err>" | b"err+out>" | b"o+e>" | b"e+o>" => (
-            Token {
-                contents: TokenContents::OutErrGreaterThan,
-                span,
-            },
-            None,
-        ),
-        b"&&" => (
+    let mut err = None;
+    let output = match &input[(span.start - span_offset)..(span.end - span_offset)] {
+        b"out>" | b"o>" => Token {
+            contents: TokenContents::OutGreaterThan,
+            span,
+        },
+        b"err>" | b"e>" => Token {
+            contents: TokenContents::ErrGreaterThan,
+            span,
+        },
+        b"out+err>" | b"err+out>" | b"o+e>" | b"e+o>" => Token {
+            contents: TokenContents::OutErrGreaterThan,
+            span,
+        },
+        b"&&" => {
+            err = Some(ParseError::ShellAndAnd(span));
             Token {
                 contents: TokenContents::Item,
                 span,
-            },
-            Some(ParseError::ShellAndAnd(span)),
-        ),
-        b"2>" => (
+            }
+        }
+        b"2>" => {
+            err = Some(ParseError::ShellErrRedirect(span));
             Token {
                 contents: TokenContents::Item,
                 span,
-            },
-            Some(ParseError::ShellErrRedirect(span)),
-        ),
-        b"2>&1" => (
+            }
+        }
+        b"2>&1" => {
+            err = Some(ParseError::ShellOutErrRedirect(span));
             Token {
                 contents: TokenContents::Item,
                 span,
-            },
-            Some(ParseError::ShellOutErrRedirect(span)),
-        ),
-        _ => (
-            Token {
-                contents: TokenContents::Item,
-                span,
-            },
-            None,
-        ),
-    }
+            }
+        }
+        _ => Token {
+            contents: TokenContents::Item,
+            span,
+        },
+    };
+    (output, err)
 }
 
 pub fn lex_signature(