1 files changed, 47 insertions, 0 deletions
diff --git a/projects/hackc/utils.py b/projects/hackc/utils.py
index d375953..8756e46 100644
--- a/projects/hackc/utils.py
+++ b/projects/hackc/utils.py
@@ -1,5 +1,31 @@
 from sys import stderr
 
+KEYWORDS = [
+    "class",
+    "constructor",
+    "function",
+    "method",
+    "field",
+    "static",
+    "var",
+    "int",
+    "char",
+    "boolean",
+    "void",
+    "true",
+    "false",
+    "null",
+    "this",
+    "let",
+    "do",
+    "if",
+    "else",
+    "while",
+    "return",
+]
+
+SYMBOLS = "{}()[].,;+-*/&|<>=~"
+
 EXIT_CODE_FILE_ERROR = 1
 EXIT_CODE_INVALID_TOKEN = 2
 EXIT_CODE_SYNTAX_ERROR = 4
@@ -13,6 +39,7 @@ RIGHT_BRACKET = "]"
 LEFT_PAREN = "("
 RIGHT_PAREN = ")"
 
+
 class JackSyntaxError(Exception):
     def __init__(self, msg, token):
         self.message = msg
@@ -20,5 +47,25 @@ class JackSyntaxError(Exception):
         super().__init__(msg)
 
 
+class UnexpectedToken(JackSyntaxError):
+    def __init__(self, expected, unexpected):
+        if str(expected) in KEYWORDS or str(expected) in SYMBOLS:
+            # wrap literal keyword/symbol in backticks
+            super().__init__(
+                f"Expected `{expected}`, got `{unexpected}` instead", unexpected
+            )
+        else:
+            super().__init__(
+                f"Expected {expected}, got `{unexpected}` instead", unexpected
+            )
+
+
+class Unexpected(JackSyntaxError):
+    def __init__(self, expected, unexpected):
+        super().__init__(
+            f"Expected `{expected}`, got `{unexpected}` instead", unexpected
+        )
+
+
 def print_err(msg):
     print(msg, file=stderr)