Adds initial state property to parsing table

Author: Maxcode123

src/syntactes/table.py

@@ -46,6 +46,7 @@ class LR0ParsingTable:
     def __init__(self, grammar: Grammar) -> None:
         self.rows: dict[LR0State, Row] = dict()
         self._grammar = grammar
+        self._initial_state = None
 
     def get_actions(self, state: LR0State, token: Token) -> Optional[list[Action]]:
         """
@@ -65,9 +66,12 @@ def add_entry(self, entry: Entry) -> None:
         """
         Adds an entry to the parsing table.
         """
-        self.rows.setdefault(entry.from_state, {}).setdefault(
-            entry.token, list()
-        ).append(entry.action)
+        if entry.from_state.number == 1:
+            self._initial_state = entry.from_state
+
+        row = self.rows.setdefault(entry.from_state, {})
+        actions = row.setdefault(entry.token, list())
+        actions.append(entry.action)
 
     @staticmethod
     def from_entries(
@@ -86,6 +90,10 @@ def pretty_str(self) -> str:
         """
         return self._rules_pretty_str() + "\n\n" + self._table_pretty_str()
 
+    @property
+    def initial_state(self) -> LR0State:
+        return self._initial_state
+
     def _rules_pretty_str(self) -> str:
         rules = [str(i) + ". " + str(r) for i, r in enumerate(self._grammar.rules)]
         rules_str = "\n".join(rules)

src/syntactes/tests/test_generator.py

@@ -262,6 +262,13 @@ def test_state_6_token_plus(self):
     def test_state_6_token_x(self):
         self.assert_state_actions(reduce(rule_2))
 
+class TestLR0GeneratorGenerateInitialState(TestLR0Generator):
+    def subject(self):
+        return self.generator().generate().initial_state
+
+    def test_initial_state(self):
+        self.assertResult(state_1())
+
 
 class TestSLRGenerator(TestCase):
     def setUp(self):
@@ -370,3 +377,11 @@ def test_state_5_token_eof(self):
     @args(state_6(), EOF)
     def test_state_6_token_eof(self):
         self.assert_state_actions(reduce(rule_2))
+
+
+class TestSLRGeneratorGenerateInitialState(TestSLRGenerator):
+    def subject(self):
+        return self.generator().generate().initial_state
+
+    def test_initial_state(self):
+        self.assertResult(state_1())