Raise specific exception #7

Author: obenjiro

simplepeg/__init__.py

@@ -1 +1,2 @@
 from .speg import SPEG
+from .exceptions import GrammarParseError, TextParseError

simplepeg/exceptions.py

@@ -0,0 +1,12 @@
+class GrammarParseError(ValueError):
+    """Something is wrong with your PEG grammar"""
+    def __init__(self, message, *args):
+        self.message = message
+        super(GrammarParseError, self).__init__(message, *args)
+
+
+class TextParseError(ValueError):
+    """Something is wrong with your text"""
+    def __init__(self, message, *args):
+        self.message = message
+        super(TextParseError, self).__init__(message, *args)

simplepeg/speg.py

@@ -1,7 +1,7 @@
 from . import speg_visitor as sv
 from . import speg_parser as sp
 from . import rd_parser as rd
-
+from . import exceptions as ex
 
 class SPEG(object):
     def __init__(self):
@@ -15,7 +15,7 @@ def parse_grammar(self, grammar):
         if speg_ast:
             self.speg_parser = self.visitor.visit(speg_ast)
         else:
-            raise Exception('Failed to parse grammar: \n\n' + self.parser.get_last_error())
+            raise ex.GrammarParseError('Failed to parse grammar: \n\n' + self.parser.get_last_error())
 
     def parse_text(self, text):
         if self.speg_parser:
@@ -27,7 +27,7 @@ def parse_text(self, text):
             if ast:
                 return ast
             else:
-                raise Exception('Failed to parse text: \n\n' + rd.get_last_error(state))
+                raise ex.TextParseError('Failed to parse text: \n\n' + rd.get_last_error(state))
         else:
             raise Exception('You need grammar to parse text. Call parseGrammar first')
 
@@ -44,9 +44,9 @@ def parse(self, grammar, text):
             if ast:
                 return ast
             else:
-                raise Exception('Failed to parse text: \n\n' + rd.get_last_error(state))
+                raise ex.TextParseError('Failed to parse text: \n\n' + rd.get_last_error(state))
         else:
-            raise Exception('Failed to parse grammar: \n\n' + self.parser.get_last_error())
+            raise ex.GrammarParseError('Failed to parse grammar: \n\n' + self.parser.get_last_error())
 
 
 class SimplePegActions(object):

simplepeg/tests/test_speg_exceptions.py

@@ -0,0 +1,41 @@
+from unittest import TestCase
+
+from .. import speg as s
+
+
+class TestSPEGExceptions(TestCase):
+    def test_grammar_parser_exception(self):
+        speg = s.SPEG()
+        try:
+            speg.parse_grammar('!!!')
+        except Exception as ex:
+            self.assertEqual(type(ex).__name__, 'GrammarParseError')
+
+    def test_text_parser_exception(self):
+        speg = s.SPEG()
+        try:
+            speg.parse_grammar('GRAMMAR test a -> "A";')
+            speg.parse_text('B')
+        except Exception as ex:
+            self.assertEqual(type(ex).__name__, 'TextParseError')
+
+    def test_grammar_before_text(self):
+        speg = s.SPEG()
+        try:
+            speg.parse_text('B')
+        except Exception as ex:
+            self.assertEqual(type(ex).__name__, 'Exception')
+
+    def test_speg_parse_grammar_parser_exception(self):
+        speg = s.SPEG()
+        try:
+            speg.parse('!!!', 'B')
+        except Exception as ex:
+            self.assertEqual(type(ex).__name__, 'GrammarParseError')
+
+    def test_speg_parse_text_parser_exception(self):
+        speg = s.SPEG()
+        try:
+            speg.parse('GRAMMAR test a -> "A";', 'B')
+        except Exception as ex:
+            self.assertEqual(type(ex).__name__, 'TextParseError')