perf: levenshtein optimization (vyperlang#3780)

optimize compile time. `levenshtein` is a hotspot since it is called a
lot during type analysis to construct exceptions (which are then caught
as part of the validation routines). this commit delays calling
`levenshtein` until the last minute, and also adds a mechanism to
`VyperException` so that hints can be constructed lazily in general.

on a couple test contracts, compilation time comes down 7%. however, as
a portion of the time spent in the frontend, compilation time comes down
20-30%. this will become important as projects become larger (that is,
many imports but only some functions are actually present in codegen)
and compilation time is dominated by the frontend.

tests/functional/syntax/modules/test_initializers.py

@@ -1178,4 +1178,4 @@ def test_ownership_decl_errors_not_swallowed(make_input_bundle):
     input_bundle = make_input_bundle({"lib1.vy": lib1})
     with pytest.raises(UndeclaredDefinition) as e:
         compile_code(main, input_bundle=input_bundle)
-    assert e.value._message == "'lib2' has not been declared. "
+    assert e.value._message == "'lib2' has not been declared."

tests/functional/syntax/test_for_range.py

@@ -21,6 +21,7 @@ def foo():
     """,
         StructureException,
         "Invalid syntax for loop iterator",
+        None,
         "a[1]",
     ),
     (
@@ -32,6 +33,7 @@ def bar():
     """,
         StructureException,
         "Bound must be at least 1",
+        None,
         "0",
     ),
     (
@@ -44,6 +46,7 @@ def foo():
     """,
         StateAccessViolation,
         "Bound must be a literal",
+        None,
         "x",
     ),
     (
@@ -55,6 +58,7 @@ def foo():
     """,
         StructureException,
         "Please remove the `bound=` kwarg when using range with constants",
+        None,
         "5",
     ),
     (
@@ -66,6 +70,7 @@ def foo():
     """,
         StructureException,
         "Bound must be at least 1",
+        None,
         "0",
     ),
     (
@@ -78,6 +83,7 @@ def bar():
     """,
         ArgumentException,
         "Invalid keyword argument 'extra'",
+        None,
         "extra=3",
     ),
     (
@@ -89,6 +95,7 @@ def bar():
     """,
         StructureException,
         "End must be greater than start",
+        None,
         "0",
     ),
     (
@@ -101,6 +108,7 @@ def bar():
     """,
         StateAccessViolation,
         "Value must be a literal integer, unless a bound is specified",
+        None,
         "x",
     ),
     (
@@ -113,6 +121,7 @@ def bar():
     """,
         StateAccessViolation,
         "Value must be a literal integer, unless a bound is specified",
+        None,
         "x",
     ),
     (
@@ -125,6 +134,7 @@ def repeat(n: uint256) -> uint256:
     """,
         StateAccessViolation,
         "Value must be a literal integer, unless a bound is specified",
+        None,
         "n * 10",
     ),
     (
@@ -137,6 +147,7 @@ def bar():
     """,
         StateAccessViolation,
         "Value must be a literal integer, unless a bound is specified",
+        None,
         "x + 1",
     ),
     (
@@ -148,6 +159,7 @@ def bar():
     """,
         StructureException,
         "End must be greater than start",
+        None,
         "1",
     ),
     (
@@ -160,6 +172,7 @@ def bar():
     """,
         StateAccessViolation,
         "Value must be a literal integer, unless a bound is specified",
+        None,
         "x",
     ),
     (
@@ -172,6 +185,7 @@ def foo():
     """,
         StateAccessViolation,
         "Value must be a literal integer, unless a bound is specified",
+        None,
         "x",
     ),
     (
@@ -184,6 +198,7 @@ def repeat(n: uint256) -> uint256:
     """,
         StateAccessViolation,
         "Value must be a literal integer, unless a bound is specified",
+        None,
         "n",
     ),
     (
@@ -196,6 +211,7 @@ def foo(x: int128):
     """,
         StateAccessViolation,
         "Value must be a literal integer, unless a bound is specified",
+        None,
         "x",
     ),
     (
@@ -207,6 +223,7 @@ def bar(x: uint256):
     """,
         StateAccessViolation,
         "Value must be a literal integer, unless a bound is specified",
+        None,
         "x",
     ),
     (
@@ -221,6 +238,7 @@ def foo():
     """,
         TypeMismatch,
         "Given reference has type int128, expected uint256",
+        None,
         "FOO",
     ),
     (
@@ -234,6 +252,7 @@ def foo():
         """,
         StructureException,
         "Bound must be at least 1",
+        None,
         "FOO",
     ),
     (
@@ -244,7 +263,8 @@ def foo():
         pass
     """,
         UnknownType,
-        "No builtin or user-defined type named 'DynArra'. Did you mean 'DynArray'?",
+        "No builtin or user-defined type named 'DynArra'.",
+        "Did you mean 'DynArray'?",
         "DynArra",
     ),
     (
@@ -262,7 +282,8 @@ def foo():
         pass
     """,
         UnknownType,
-        "No builtin or user-defined type named 'uint9'. Did you mean 'uint96', or maybe 'uint8'?",
+        "No builtin or user-defined type named 'uint9'.",
+        "Did you mean 'uint96', or maybe 'uint8'?",
         "uint9",
     ),
     (
@@ -278,7 +299,8 @@ def foo():
         pass
     """,
         UnknownType,
-        "No builtin or user-defined type named 'uint9'. Did you mean 'uint96', or maybe 'uint8'?",
+        "No builtin or user-defined type named 'uint9'.",
+        "Did you mean 'uint96', or maybe 'uint8'?",
         "uint9",
     ),
 ]
@@ -289,15 +311,18 @@ def foo():
         f"{i:02d}: {for_code_regex.search(code).group(1)}"  # type: ignore[union-attr]
         f" raises {type(err).__name__}"
     )
-    for i, (code, err, msg, src) in enumerate(fail_list)
+    for i, (code, err, msg, hint, src) in enumerate(fail_list)
 ]
 
 
-@pytest.mark.parametrize("bad_code,error_type,message,source_code", fail_list, ids=fail_test_names)
-def test_range_fail(bad_code, error_type, message, source_code):
+@pytest.mark.parametrize(
+    "bad_code,error_type,message,hint,source_code", fail_list, ids=fail_test_names
+)
+def test_range_fail(bad_code, error_type, message, hint, source_code):
     with pytest.raises(error_type) as exc_info:
         compiler.compile_code(bad_code)
-    assert message == exc_info.value.message
+    assert message == exc_info.value._message
+    assert hint == exc_info.value.hint
     assert source_code == exc_info.value.args[1].get_original_node().node_source_code
 
 

vyper/exceptions.py

@@ -79,11 +79,20 @@ def with_annotation(self, *annotations):
         exc.annotations = annotations
         return exc
 
+    @property
+    def hint(self):
+        # some hints are expensive to compute, so we wait until the last
+        # minute when the formatted message is actually requested to compute
+        # them.
+        if callable(self._hint):
+            return self._hint()
+        return self._hint
+
     @property
     def message(self):
         msg = self._message
-        if self._hint:
-            msg += f"\n\n  (hint: {self._hint})"
+        if self.hint:
+            msg += f"\n\n  (hint: {self.hint})"
         return msg
 
     def __str__(self):

vyper/semantics/analysis/levenshtein_utils.py

@@ -1,4 +1,4 @@
-from typing import Any, Dict
+from typing import Any, Callable
 
 
 def levenshtein_norm(source: str, target: str) -> float:
@@ -73,7 +73,13 @@ def levenshtein(source: str, target: str) -> int:
     return matrix[len(source)][len(target)]
 
 
-def get_levenshtein_error_suggestions(key: str, namespace: Dict[str, Any], threshold: float) -> str:
+def get_levenshtein_error_suggestions(*args, **kwargs) -> Callable:
+    return lambda: _get_levenshtein_error_suggestions(*args, **kwargs)
+
+
+def _get_levenshtein_error_suggestions(
+    key: str, namespace: dict[str, Any], threshold: float
+) -> str:
     """
     Generate an error message snippet for the suggested closest values in the provided namespace
     with the shortest normalized Levenshtein distance from the given key if that distance

vyper/semantics/analysis/utils.py

@@ -208,9 +208,9 @@ def _raise_invalid_reference(name, node):
             if name in self.namespace:
                 _raise_invalid_reference(name, node)
 
-            suggestions_str = get_levenshtein_error_suggestions(name, t.members, 0.4)
+            hint = get_levenshtein_error_suggestions(name, t.members, 0.4)
             raise UndeclaredDefinition(
-                f"Storage variable '{name}' has not been declared. {suggestions_str}", node
+                f"Storage variable '{name}' has not been declared.", node, hint=hint
             ) from None
 
     def types_from_BinOp(self, node):

vyper/semantics/namespace.py

@@ -45,8 +45,8 @@ def __setitem__(self, attr, obj):
 
     def __getitem__(self, key):
         if key not in self:
-            suggestions_str = get_levenshtein_error_suggestions(key, self, 0.2)
-            raise UndeclaredDefinition(f"'{key}' has not been declared. {suggestions_str}")
+            hint = get_levenshtein_error_suggestions(key, self, 0.2)
+            raise UndeclaredDefinition(f"'{key}' has not been declared.", hint=hint)
         return super().__getitem__(key)
 
     def __enter__(self):

vyper/semantics/types/base.py

@@ -321,8 +321,8 @@ def get_member(self, key: str, node: vy_ast.VyperNode) -> "VyperType":
         if not self.members:
             raise StructureException(f"{self} instance does not have members", node)
 
-        suggestions_str = get_levenshtein_error_suggestions(key, self.members, 0.3)
-        raise UnknownAttribute(f"{self} has no member '{key}'. {suggestions_str}", node)
+        hint = get_levenshtein_error_suggestions(key, self.members, 0.3)
+        raise UnknownAttribute(f"{self} has no member '{key}'.", node, hint=hint)
 
     def __repr__(self):
         return self._id

vyper/semantics/types/user.py

@@ -399,9 +399,9 @@ def _ctor_call_return(self, node: vy_ast.Call) -> "StructT":
         keys = list(self.member_types.keys())
         for i, (key, value) in enumerate(zip(node.args[0].keys, node.args[0].values)):
             if key is None or key.get("id") not in members:
-                suggestions_str = get_levenshtein_error_suggestions(key.get("id"), members, 1.0)
+                hint = get_levenshtein_error_suggestions(key.get("id"), members, 1.0)
                 raise UnknownAttribute(
-                    f"Unknown or duplicate struct member. {suggestions_str}", key or value
+                    "Unknown or duplicate struct member.", key or value, hint=hint
                 )
             expected_key = keys[i]
             if key.id != expected_key:

vyper/semantics/types/utils.py

@@ -146,10 +146,9 @@ def _type_from_annotation(node: vy_ast.VyperNode) -> VyperType:
         raise InvalidType(err_msg, node)
 
     if node.id not in namespace:  # type: ignore
-        suggestions_str = get_levenshtein_error_suggestions(node.node_source_code, namespace, 0.3)
+        hint = get_levenshtein_error_suggestions(node.node_source_code, namespace, 0.3)
         raise UnknownType(
-            f"No builtin or user-defined type named '{node.node_source_code}'. {suggestions_str}",
-            node,
+            f"No builtin or user-defined type named '{node.node_source_code}'.", node, hint=hint
         ) from None
 
     typ_ = namespace[node.id]