🐐 Array indexing

centvrion/ast_nodes.py

@@ -342,6 +342,24 @@ class UnaryMinus(Node):
     return vtable, ValInt(-val.value())
 
 
+class ArrayIndex(Node):
+  def __init__(self, array, index) -> None:
+    self.array = array
+    self.index = index
+
+  def __repr__(self) -> str:
+    return f"ArrayIndex({self.array!r}, {self.index!r})"
+
+  def _eval(self, vtable):
+    vtable, array = self.array.eval(vtable)
+    vtable, index = self.index.eval(vtable)
+    i = index.value()
+    lst = array.value()
+    if i < 1 or i > len(lst):
+      raise IndexError(f"Index {i} out of range for array of length {len(lst)}")
+    return vtable, lst[i - 1]
+
+
 class SiStatement(Node):
   def __init__(self, test, statements, else_part) -> None:
     self.test = test

centvrion/parser.py

@@ -16,6 +16,7 @@ class Parser():
         ('left', ["SYMBOL_PLUS", "SYMBOL_MINUS"]),
         ('left', ["SYMBOL_TIMES", "SYMBOL_DIVIDE"]),
         ('right', ["UMINUS"]),
+        ('left', ["INDEX"]),
       ]
     )
 
@@ -194,6 +195,10 @@ class Parser():
     def range_array(tokens):
       return ast_nodes.DataRangeArray(tokens[1], tokens[3])
 
+    @self.pg.production('expression : expression SYMBOL_LBRACKET expression SYMBOL_RBRACKET', precedence='INDEX')
+    def array_index(tokens):
+      return ast_nodes.ArrayIndex(tokens[0], tokens[2])
+
     # ids
     @self.pg.production('ids : SYMBOL_LPARENS id_list')
     def ids(tokens):