bugfix: fail gracefully when parens are uneven

2 files changed, 11 insertions, 1 deletions

diff --git a/neb/exceptions.py b/neb/exceptions.py
index 8bbe000..cc0f915 100644
--- a/neb/exceptions.py
+++ b/neb/exceptions.py
@@ -11,3 +11,7 @@ class InterpretPanic(NebPanic):
 class LexError(NebPanic):
     def __init__(self, message, line):
         super().__init__(f"line {line}: {message}")
+
+class ParseError(NebPanic):
+    def __init__(self, message, line):
+        super().__init__(f"line {line}: {message}")
diff --git a/neb/parser.py b/neb/parser.py
index 5352ee5..08ab0be 100644
--- a/neb/parser.py
+++ b/neb/parser.py
@@ -1,4 +1,6 @@
 from .structs import *
+from .exceptions import ParseError
+
 
 def parseExpression(token, prev, tokens):
     idx = 0
@@ -6,6 +8,8 @@ def parseExpression(token, prev, tokens):
     prev = token
     while tokens[idx].type_ != TokenType.CLOSE_PAREN:
         token = tokens[idx]
+        if token.type_ == TokenType.EOF:
+            raise ParseError("uneven parens: not enough closing!", token.line)
         inc = 1
         if token.type_ == TokenType.OPEN_PAREN:
             expr, inc = parseExpression(token, prev, tokens[idx+1:])
@@ -49,7 +53,9 @@ def parse(tokens):
     while tokens[idx].type_ != TokenType.EOF:
         token = tokens[idx]
         counter = 1
-        if token.type_ == TokenType.OPEN_PAREN:
+        if token.type_ == TokenType.CLOSE_PAREN:
+            raise ParseError("uneven parens: too many closing!", token.line)
+        elif token.type_ == TokenType.OPEN_PAREN:
             expr, counter = parseExpression(token, prev, tokens[idx+1:])
             exprs.append(expr)
         elif token.type_ in (TokenType.FALSE, TokenType.TRUE, TokenType.STRING, TokenType.INT, TokenType.FLOAT):