Decode escaped backslashes in raw string literals

CHANGELOG.rst

@@ -1,7 +1,7 @@
 Next Release (TBD)
 ==================
 
-* No changes yet.
+* Decode escaped backslashes in raw string literals according to the language specification.
 
 
 1.1.0

jmespath/lexer.py

@@ -191,9 +191,19 @@ def _consume_quoted_identifier(self):
 
     def _consume_raw_string_literal(self):
         start = self._position
-        lexeme = self._consume_until("'").replace("\\'", "'")
+        lexeme = self._consume_until("'")
+        raw_string = []
+        i = 0
+        while i < len(lexeme):
+            char = lexeme[i]
+            if (char == '\\' and i + 1 < len(lexeme) and
+                    lexeme[i + 1] in ("\\", "'")):
+                i += 1
+                char = lexeme[i]
+            raw_string.append(char)
+            i += 1
         token_len = self._position - start
-        return {'type': 'literal', 'value': lexeme,
+        return {'type': 'literal', 'value': ''.join(raw_string),
                 'start': start, 'end': token_len}
 
     def _match_or_else(self, expected, match_type, else_type):

tests/compliance/literal.json

@@ -191,9 +191,9 @@
           "result": "\\z"
         },
         {
-          "comment": "Backslash not followed by single quote is treated as any other character",
+          "comment": "Backslash escapes a backslash in a raw string",
           "expression": "'\\\\'",
-          "result": "\\\\"
+          "result": "\\"
         }
       ]
     }

tests/test_raw_string_escapes.py

@@ -0,0 +1,23 @@
+from tests import unittest
+
+import jmespath
+from jmespath.lexer import Lexer
+
+
+class TestRawStringEscapes(unittest.TestCase):
+
+    def test_escaped_backslash_is_unescaped(self):
+        tokens = list(Lexer().tokenize(r"'\\'"))
+        self.assertEqual(tokens[0]['value'], '\\')
+        self.assertEqual(jmespath.search(r"'\\'", {}), '\\')
+
+    def test_backslash_before_other_character_is_preserved(self):
+        self.assertEqual(jmespath.search(r"'\z'", {}), r'\z')
+
+    def test_escaped_quote_is_unescaped(self):
+        self.assertEqual(jmespath.search(r"'foo\'bar'", {}), "foo'bar")
+
+    def test_windows_path_filter_with_trailing_backslash(self):
+        rows = [{'FullName': r'C:\x\msvc\file.txt'}]
+        expression = r"[? !contains(FullName, '\msvc\\')]"
+        self.assertEqual(jmespath.search(expression, rows), [])