From 6074ab1c3821e7d040512582756be789844b06c4 Mon Sep 17 00:00:00 2001
From: Alexis <alexis.challande@trailofbits.com>
Date: Fri, 19 Apr 2024 10:54:37 +0200
Subject: [PATCH] Remove calls to isinstance to improve performances.

---
 slither/visitors/expression/expression.py | 79 +++++++++--------------
 1 file changed, 29 insertions(+), 50 deletions(-)

diff --git a/slither/visitors/expression/expression.py b/slither/visitors/expression/expression.py
index 41886a1023..860ca28503 100644
--- a/slither/visitors/expression/expression.py
+++ b/slither/visitors/expression/expression.py
@@ -1,4 +1,5 @@
 import logging
+from functools import cache
 
 from slither.core.expressions.assignment_operation import AssignmentOperation
 from slither.core.expressions.binary_operation import BinaryOperation
@@ -21,6 +22,28 @@
 logger = logging.getLogger("ExpressionVisitor")
 
 
+@cache
+def get_visitor_mapping():
+    """Returns a visitor mapping from expression type to visiting functions."""
+    return {
+        AssignmentOperation: '_visit_assignement_operation',
+        BinaryOperation: '_visit_binary_operation',
+        CallExpression: '_visit_call_expression',
+        ConditionalExpression: '_visit_conditional_expression',
+        ElementaryTypeNameExpression: '_visit_elementary_type_name_expression',
+        Identifier: '_visit_identifier',
+        IndexAccess: '_visit_index_access',
+        Literal: '_visit_literal',
+        MemberAccess: '_visit_member_access',
+        NewArray: '_visit_new_array',
+        NewContract: '_visit_new_contract',
+        NewElementaryType: '_visit_new_elementary_type',
+        TupleExpression: '_visit_tuple_expression',
+        TypeConversion: '_visit_type_conversion',
+        UnaryOperation: '_visit_unary_operation'
+    }
+
+
 # pylint: disable=too-few-public-methods
 class ExpressionVisitor:
     def __init__(self, expression: Expression) -> None:
@@ -35,60 +58,16 @@ def expression(self) -> Expression:
 
     # visit an expression
     # call pre_visit, visit_expression_name, post_visit
-    # pylint: disable=too-many-branches
     def _visit_expression(self, expression: Expression) -> None:
         self._pre_visit(expression)
 
-        if isinstance(expression, AssignmentOperation):
-            self._visit_assignement_operation(expression)
-
-        elif isinstance(expression, BinaryOperation):
-            self._visit_binary_operation(expression)
-
-        elif isinstance(expression, CallExpression):
-            self._visit_call_expression(expression)
-
-        elif isinstance(expression, ConditionalExpression):
-            self._visit_conditional_expression(expression)
-
-        elif isinstance(expression, ElementaryTypeNameExpression):
-            self._visit_elementary_type_name_expression(expression)
-
-        elif isinstance(expression, Identifier):
-            self._visit_identifier(expression)
-
-        elif isinstance(expression, IndexAccess):
-            self._visit_index_access(expression)
-
-        elif isinstance(expression, Literal):
-            self._visit_literal(expression)
-
-        elif isinstance(expression, MemberAccess):
-            self._visit_member_access(expression)
-
-        elif isinstance(expression, NewArray):
-            self._visit_new_array(expression)
-
-        elif isinstance(expression, NewContract):
-            self._visit_new_contract(expression)
-
-        elif isinstance(expression, NewElementaryType):
-            self._visit_new_elementary_type(expression)
-
-        elif isinstance(expression, TupleExpression):
-            self._visit_tuple_expression(expression)
+        if expression is not None:
+            visitor_method = get_visitor_mapping().get(expression.__class__)
+            if not visitor_method:
+                raise SlitherError(f"Expression not handled: {expression}")
 
-        elif isinstance(expression, TypeConversion):
-            self._visit_type_conversion(expression)
-
-        elif isinstance(expression, UnaryOperation):
-            self._visit_unary_operation(expression)
-
-        elif expression is None:
-            pass
-
-        else:
-            raise SlitherError(f"Expression not handled: {expression}")
+            visitor = getattr(self, visitor_method)
+            visitor(expression)
 
         self._post_visit(expression)