From 4db58148cf9f942b0783b2728261df2098958877 Mon Sep 17 00:00:00 2001
From: piegames <git@piegames.de>
Date: Thu, 14 Mar 2024 17:44:15 +0100
Subject: [PATCH] Parser: Fix operator parsing

Closes #122
---
 src/Nixfmt/Parser.hs                     | 16 ++++++++++++----
 test/correct/operator-after-operator.nix |  3 +++
 2 files changed, 15 insertions(+), 4 deletions(-)
 create mode 100644 test/correct/operator-after-operator.nix

diff --git a/src/Nixfmt/Parser.hs b/src/Nixfmt/Parser.hs
index 647283d9..92ca7622 100644
--- a/src/Nixfmt/Parser.hs
+++ b/src/Nixfmt/Parser.hs
@@ -342,12 +342,20 @@ list = List <$> symbol TBrackOpen <*> items term <*> symbol TBrackClose
 
 -- OPERATORS
 
-opChars :: [Char]
-opChars = "<>=+*/."
-
 operator :: Token -> Parser Leaf
 operator t = label "operator" $ try $ lexeme $
-    rawSymbol t <* notFollowedBy (oneOf opChars)
+    rawSymbol t <* notFollowedBy (oneOf (
+        -- Resolve ambiguities between operators which are prefixes of others
+        case t of
+            TPlus -> "+" :: [Char]
+            TMinus -> ">"
+            TMul -> "/"
+            TDiv -> "/*"
+            TLess -> "="
+            TGreater -> "="
+            TNot -> "="
+            _ -> ""
+    ))
 
 opCombiner :: Operator -> MPExpr.Operator Parser Expression
 opCombiner Apply = MPExpr.InfixL $ return Application
diff --git a/test/correct/operator-after-operator.nix b/test/correct/operator-after-operator.nix
new file mode 100644
index 00000000..d4ba6740
--- /dev/null
+++ b/test/correct/operator-after-operator.nix
@@ -0,0 +1,3 @@
+# https://github.com/NixOS/nixfmt/issues/122
+(1+/**/1)
+(1+.4)