hackc: print syntax error message

1 files changed, 21 insertions, 10 deletions

diff --git a/projects/hackc/syntax.py b/projects/hackc/syntax.py
index c9be157..a07e69e 100644
--- a/projects/hackc/syntax.py
+++ b/projects/hackc/syntax.py
@@ -41,8 +41,15 @@ class Class:
                 f"Expected `{LEFT_BRACE}`, got `{tokens[2]}` instead", tokens[2]
             )
 
-        variables = Variable.from_tokens(tokens[3:])
-        variables.print_verbose()
+        tokens_consumed = 3
+
+        while True:
+            variables, token_cnt = Variable.from_tokens(tokens[tokens_consumed:])
+            if variables is None:
+                break
+            variables.print_verbose()
+            tokens_consumed += token_cnt
+
         return Class(name, variables, [])
 
 
@@ -53,10 +60,9 @@ class Variable:
         self.names = names
 
     @classmethod
-    def from_tokens(cls, tokens: list):
+    def from_tokens(cls, tokens: list) -> tuple:
         """Construct variable declaration statement.
-
-        You can declare multiple variables of one scope and type on the same line.
+        Return a tuple of a Variable instance and number of tokens consumed.
 
         Format:
         <scope> <type> <one or more names, joined with a comma>;
@@ -66,7 +72,7 @@ class Variable:
         """
         if len(tokens) < 4 or tokens[0] not in SCOPES:
             # not variable declaration
-            return None
+            return (None, 0)
 
         scope = tokens[0]
 
@@ -77,10 +83,12 @@ class Variable:
 
         type = tokens[1]
 
+        tokens_consumed = 2
         names = []  # names of variables
         expecting_identifier = True
 
         for token in tokens[2:]:
+            tokens_consumed += 1
             if token.type == "identifier":
                 if expecting_identifier:
                     names.append(token)
@@ -94,19 +102,22 @@ class Variable:
                     expecting_identifier = True
                 else:
                     raise JackSyntaxError(
-                        f"Expected identifier, got `,` instead", token
+                        f"Expected variable name, got `,` instead", token
                     )
             elif token == ";":
                 if expecting_identifier:
                     raise JackSyntaxError(
-                        f"Expected identifier, got `;` instead", token
+                        f"Expected variable name, got `;` instead", token
                     )
                 break
+            else:
+                expected = "variable name" if expecting_identifier else "`,` or `;`"
+                raise JackSyntaxError(f"Expected {expected}, got `{token}` instead", token)
 
-        return Variable(scope, type, names)
+        return (Variable(scope, type, names), tokens_consumed)
 
     def print_verbose(self):
-        print(f"Declare {len(self.names)} variables:")
+        print(f"Declare {len(self.names)} variable(s):")
         for name in self.names:
             print(self.scope, self.type, name)