From 17289d480c153200c2944b260aa50b58b904e8be Mon Sep 17 00:00:00 2001
From: Hamish Knight <hamish_github@mediocremail.com>
Date: Thu, 23 Mar 2023 13:13:22 +0000
Subject: [PATCH] Remove check for `endOfFile` in `advance`

Instead, let the lexer produce `.eof` itself. This
will be needed for regex literal lexing, where the
lexer may still want to produce an empty regex
literal pattern when at the end of the file, before
the `.eof` token.
---
 Sources/SwiftParser/Lexer/Cursor.swift         |  2 ++
 Sources/SwiftParser/Lexer/LexemeSequence.swift | 15 +--------------
 2 files changed, 3 insertions(+), 14 deletions(-)

diff --git a/Sources/SwiftParser/Lexer/Cursor.swift b/Sources/SwiftParser/Lexer/Cursor.swift
index 16f5deb09b1..9717ba1a2fc 100644
--- a/Sources/SwiftParser/Lexer/Cursor.swift
+++ b/Sources/SwiftParser/Lexer/Cursor.swift
@@ -1772,6 +1772,8 @@ extension Lexer.Cursor {
   }
 
   mutating func lexInStringLiteral(stringLiteralKind: StringLiteralKind, delimiterLength: Int) -> Lexer.Result {
+    if self.isAtEndOfFile { return .init(.eof) }
+
     var error: LexingDiagnostic? = nil
 
     while true {
diff --git a/Sources/SwiftParser/Lexer/LexemeSequence.swift b/Sources/SwiftParser/Lexer/LexemeSequence.swift
index 138e6f74ba3..266cbe4db9c 100644
--- a/Sources/SwiftParser/Lexer/LexemeSequence.swift
+++ b/Sources/SwiftParser/Lexer/LexemeSequence.swift
@@ -43,20 +43,7 @@ extension Lexer {
 
     mutating func advance() -> Lexer.Lexeme {
       defer {
-        if self.cursor.isAtEndOfFile {
-          self.nextToken = Lexeme(
-            tokenKind: .eof,
-            flags: [],
-            diagnostic: nil,
-            start: self.cursor.pointer,
-            leadingTriviaLength: 0,
-            textLength: 0,
-            trailingTriviaLength: 0,
-            cursor: self.cursor
-          )
-        } else {
-          self.nextToken = self.cursor.nextToken(sourceBufferStart: self.sourceBufferStart, stateAllocator: lexerStateAllocator)
-        }
+        self.nextToken = self.cursor.nextToken(sourceBufferStart: self.sourceBufferStart, stateAllocator: lexerStateAllocator)
       }
       return self.nextToken
     }