Implement getattr operation

hisscl/ast.py

@@ -86,7 +86,13 @@ class Index:
     value: 'Value'
     index: 'Value'
     
-Expression = BinaryExpression | UnaryExpression | Expansion | Index
+@dataclasses.dataclass
+class GetAttr:
+    pos: Position
+    value: 'Value'
+    attr: str
+    
+Expression = BinaryExpression | UnaryExpression | Expansion | Index | GetAttr
 Value = Literal | Collection | Expression | Ref
 
 @dataclasses.dataclass

hisscl/interp.py

@@ -65,6 +65,11 @@ class Interp:
             return self._eval_unary_expr(val)
         elif isinstance(val, ast.Index):
             return self._eval_index(val)
+        elif isinstance(val, ast.GetAttr):
+            obj = self._convert_value(val.value)
+            if not hasattr(obj, val.attr):
+                raise AttributeError(f'{val.pos}: no such attribute {repr(val.attr)} in object of type {type(obj).__name__}')
+            return getattr(obj, val.attr)
         elif isinstance(val, ast.Expansion):
             raise ValueError(f'{val.pos}: cannot use expansion operator outside of a function call')
     

hisscl/lexer.py

@@ -25,6 +25,7 @@ class Token(enum.Enum):
     COLON = 12
     OPERATOR = 13
     ELLIPSIS = 14
+    DOT = 15
 
 class ExpectedError(Exception):
     def __init__(self, pos: ast.Position, expected: str, got: str):
@@ -228,8 +229,9 @@ class Lexer:
                 return self.scan()
             case '.':
                 if (next := self._read()) != '.':
-                    raise ExpectedError(self.pos, '.', next)
-                if (next := self._read()) != '.':
+                    self._unread(next)
+                    return Token.DOT, self.pos, next
+                elif (next := self._read()) != '.':
                     raise ExpectedError(self.pos, '.', next)
                 return Token.ELLIPSIS, self.pos, "..."
             case '':

hisscl/parser.py

@@ -29,15 +29,27 @@ class Parser:
     def _unscan(self, tok: lexer.Token, pos: ast.Position, lit: str):
         self._prev = tok, pos, lit
     
-    def _parse_index(self, val: ast.Value) -> ast.Index:
-        index = ast.Index(pos=val.pos, value=val, index=self._parse_expr())
-        tok, pos, lit = self._scan()
+    def _parse_index(self, val: ast.Value, start_pos: ast.Position) -> ast.Index:
+        index = ast.Index(pos=start_pos, value=val, index=self._parse_expr())
+        tok, start_pos, lit = self._scan()
         if tok != lexer.Token.SQUARE or lit != ']':
-            raise ExpectedError(pos, 'closing square bracket', lit)
+            raise ExpectedError(start_pos, 'closing square bracket', lit)
         while self.lexer._peek(1) == '[':
-            self._scan()
-            index = self._parse_index(index)
+            _, start_pos, _ = self._scan()
+            index = self._parse_index(index, start_pos)
         return index
+        
+    def _parse_getattr(self, val: ast.Value, start_pos: ast.Position) -> ast.Index | ast.GetAttr:
+        tok, pos, lit = self._scan()
+        if tok == lexer.Token.INTEGER:
+            return ast.Index(pos=start_pos, value=val, index=ast.Integer(pos=pos, value=int(lit)))
+        elif tok == lexer.Token.IDENT:
+            return ast.GetAttr(pos=start_pos, value=val, attr=lit)
+        else:
+            raise ExpectedError(pos, 'integer or identifier', lit)
+        while self.lexer._peek(1) == '.':
+            _, start_pos, _ = self._scan()
+            index = self._parse_getattr(index, start_pos)
       
     def _parse_expr(self) -> ast.Value:
         left = self._parse_value()
@@ -156,9 +168,13 @@ class Parser:
             case _:
                 raise ExpectedError(pos, 'value', lit)
         
-        if self.lexer._peek(1) == '[':
-            self._scan()
-            out = self._parse_index(out)
+        tok, pos, lit = self._scan()
+        if tok == lexer.Token.SQUARE and lit == '[':
+            out = self._parse_index(out, pos)
+        elif tok == lexer.Token.DOT:
+            out = self._parse_getattr(out, pos)
+        else:
+            self._unscan(tok, pos, lit)
         
         return out
         

test/test_interp.py

@@ -114,6 +114,22 @@ class TestRefs(unittest.TestCase):
         cfg = interp.Interp(io.StringIO('x = ["123", "456", "789"][1][2]'), "TestRefs.test_multi_index").run()
         self.assertIn('x', cfg)
         self.assertEqual(cfg['x'], '6')
+        
+    def test_index_legacy(self):
+        i = interp.Interp(io.StringIO('x = y.1'), "TestRefs.test_index_legacy")
+        i['y'] = [123, 456, 789]
+        cfg = i.run()
+        self.assertIn('x', cfg)
+        self.assertEqual(cfg['x'], 456)
+        
+    def test_getattr(self):
+        class Y:
+            z = 123
+        i = interp.Interp(io.StringIO('x = Y.z'), "TestRefs.test_getattr")
+        i['Y'] = Y()
+        cfg = i.run()
+        self.assertIn('x', cfg)
+        self.assertEqual(cfg['x'], 123)
 
     def test_func(self):
         def y(a, b):

test/test_parser.py

@@ -205,6 +205,29 @@ class TestExpressions(unittest.TestCase):
             pos = ast.Position(name='TestExpressions.test_index', line=1, col=3),
             value = 0,
         ))
+        
+    def test_index_legacy(self):
+        val = parser.Parser(io.StringIO('x.0'), 'TestExpressions.test_index_legacy')._parse_expr()
+        self.assertIsInstance(val, ast.Index)
+        assert type(val) is ast.Index
+        self.assertEqual(val.value, ast.VariableRef(
+            pos = ast.Position(name='TestExpressions.test_index_legacy', line=1, col=1),
+            name = 'x',
+        ))
+        self.assertEqual(val.index, ast.Integer(
+            pos = ast.Position(name='TestExpressions.test_index_legacy', line=1, col=3),
+            value = 0,
+        ))
+        
+    def test_getattr(self):
+        val = parser.Parser(io.StringIO('x.y'), 'TestExpressions.test_getattr')._parse_expr()
+        self.assertIsInstance(val, ast.GetAttr)
+        assert type(val) is ast.GetAttr
+        self.assertEqual(val.value, ast.VariableRef(
+            pos = ast.Position(name='TestExpressions.test_getattr', line=1, col=1),
+            name = 'x',
+        ))
+        self.assertEqual(val.attr, 'y')
     
     def test_unary(self):
         val = parser.Parser(io.StringIO('!true'), 'TestExpressions.test_unary')._parse_value()