avoid using StringScanner eos

lib/liquid/lexer.rb

@@ -181,7 +181,7 @@ module Liquid
             @output << DOTDOT
           elsif special == DASH
             # Special case for negative numbers
-            if !@ss.eos? && NUMBER_TABLE[@ss.peek_byte]
+            if (peeked_byte = @ss.peek_byte) && NUMBER_TABLE[peeked_byte]
               @ss.pos -= 1
               @output << [:number, @ss.scan(NUMBER_LITERAL)]
             else
@@ -192,7 +192,7 @@ module Liquid
           end
         elsif (sub_table = TWO_CHARS_COMPARISON_JUMP_TABLE[peeked])
           @ss.scan_byte
-          if !@ss.eos? && (found = sub_table[@ss.peek_byte])
+          if (peeked_byte = @ss.peek_byte) && (found = sub_table[peeked_byte])
             @output << found
             @ss.scan_byte
           else
@@ -200,7 +200,7 @@ module Liquid
           end
         elsif (sub_table = COMPARISON_JUMP_TABLE[peeked])
           @ss.scan_byte
-          if !@ss.eos? && (found = sub_table[@ss.peek_byte])
+          if (peeked_byte = @ss.peek_byte) && (found = sub_table[peeked_byte])
             @output << found
             @ss.scan_byte
           else

test/unit/lexer_unit_test.rb

@@ -108,7 +108,7 @@ class LexerUnitTest < Minitest::Test
 
   def test_error_with_utf8_character
     error = assert_raises(SyntaxError) do
-      Lexer.new("1 < 1Ø").tokenize
+      tokenize("1 < 1Ø")
     end
 
     assert_equal(
@@ -120,7 +120,7 @@ class LexerUnitTest < Minitest::Test
   def test_contains_as_attribute_name
     assert_equal(
       [[:id, "a"], [:dot, "."], [:id, "contains"], [:dot, "."], [:id, "b"], [:end_of_string]],
-      Lexer.new("a.contains.b").tokenize,
+      tokenize("a.contains.b"),
     )
   end