Remove unused SymbolTable (#10544)

All members of the `SymbolTable` are `TargetAdaptor`, so there is no reason for this dictionary anymore.

[ci skip-rust]
[ci skip-build-wheels]

src/python/pants/engine/internals/build_files_test.py

@@ -30,7 +30,7 @@
     strip_address_origins,
 )
 from pants.engine.internals.mapper import AddressFamily, AddressMapper
-from pants.engine.internals.parser import BuildFilePreludeSymbols, Parser, SymbolTable
+from pants.engine.internals.parser import BuildFilePreludeSymbols, Parser
 from pants.engine.internals.scheduler import ExecutionError
 from pants.engine.internals.target_adaptor import TargetAdaptor
 from pants.engine.rules import RootRule
@@ -42,7 +42,9 @@
 
 def test_parse_address_family_empty() -> None:
     """Test that parsing an empty BUILD file results in an empty AddressFamily."""
-    address_mapper = AddressMapper(parser=Parser(SymbolTable({}), BuildFileAliases()))
+    address_mapper = AddressMapper(
+        parser=Parser(target_type_aliases=[], object_aliases=BuildFileAliases())
+    )
     af = run_rule(
         parse_address_family,
         rule_args=[address_mapper, BuildFilePreludeSymbols(FrozenDict()), Dir("/dev/null")],
@@ -60,7 +62,9 @@ def test_parse_address_family_empty() -> None:
 def resolve_addresses_with_origins_from_address_specs(
     address_specs: AddressSpecs, address_family: AddressFamily,
 ) -> AddressesWithOrigins:
-    address_mapper = AddressMapper(Parser(SymbolTable({}), BuildFileAliases()))
+    address_mapper = AddressMapper(
+        Parser(target_type_aliases=[], object_aliases=BuildFileAliases())
+    )
     snapshot = Snapshot(Digest("xx", 2), ("root/BUILD",), ())
     addresses_with_origins = run_rule(
         addresses_with_origins_from_address_specs,

src/python/pants/engine/internals/mapper_test.py

@@ -9,14 +9,14 @@
 from pants.build_graph.address import Address
 from pants.build_graph.build_file_aliases import BuildFileAliases
 from pants.engine.internals.mapper import AddressFamily, AddressMap, DifferingFamiliesError
-from pants.engine.internals.parser import BuildFilePreludeSymbols, Parser, SymbolTable
+from pants.engine.internals.parser import BuildFilePreludeSymbols, Parser
 from pants.engine.internals.target_adaptor import TargetAdaptor
 from pants.util.frozendict import FrozenDict
 
 
 def parse_address_map(build_file: str) -> AddressMap:
     path = "/dev/null"
-    parser = Parser(SymbolTable({"thing": TargetAdaptor}), BuildFileAliases())
+    parser = Parser(target_type_aliases=["thing"], object_aliases=BuildFileAliases())
     address_map = AddressMap.parse(path, build_file, parser, BuildFilePreludeSymbols(FrozenDict()))
     assert path == address_map.path
     return address_map

src/python/pants/engine/internals/parser.py

@@ -5,7 +5,7 @@
 import tokenize
 from dataclasses import dataclass
 from io import StringIO
-from typing import Any, Dict, List, Tuple, Type, cast
+from typing import Any, Dict, Iterable, List, Tuple, cast
 
 from pants.base.exceptions import UnaddressableObjectError
 from pants.base.parse_context import ParseContext
@@ -14,13 +14,6 @@
 from pants.util.frozendict import FrozenDict
 
 
-@dataclass(frozen=True)
-class SymbolTable:
-    """A symbol table dict mapping symbol name to implementation class."""
-
-    table: Dict[str, Type]
-
-
 @dataclass(frozen=True)
 class BuildFilePreludeSymbols:
     symbols: FrozenDict[str, Any]
@@ -31,12 +24,16 @@ class ParseError(Exception):
 
 
 class Parser:
-    def __init__(self, symbol_table: SymbolTable, aliases: BuildFileAliases) -> None:
-        self._symbols, self._parse_context = self._generate_symbols(symbol_table, aliases)
+    def __init__(
+        self, *, target_type_aliases: Iterable[str], object_aliases: BuildFileAliases
+    ) -> None:
+        self._symbols, self._parse_context = self._generate_symbols(
+            target_type_aliases, object_aliases
+        )
 
     @staticmethod
     def _generate_symbols(
-        symbol_table: SymbolTable, aliases: BuildFileAliases,
+        target_type_aliases: Iterable[str], object_aliases: BuildFileAliases,
     ) -> Tuple[Dict[str, Any], ParseContext]:
         symbols: Dict[str, Any] = {}
 
@@ -48,14 +45,11 @@ def _generate_symbols(
         parse_context = ParseContext(rel_path=None, type_aliases=symbols)
 
         class Registrar:
-            def __init__(self, parse_context: ParseContext, type_alias: str, object_type):
+            def __init__(self, parse_context: ParseContext, type_alias: str):
                 self._parse_context = parse_context
                 self._type_alias = type_alias
-                self._object_type = object_type
 
             def __call__(self, *args, **kwargs):
-                if not issubclass(self._object_type, TargetAdaptor):
-                    return self._object_type(*args, **kwargs)
                 # Target names default to the name of the directory their BUILD file is in
                 # (as long as it's not the root directory).
                 if "name" not in kwargs:
@@ -66,17 +60,13 @@ def __call__(self, *args, **kwargs):
                         )
                     kwargs["name"] = dirname
                 kwargs.setdefault("type_alias", self._type_alias)
-                obj = self._object_type(**kwargs)
-                self._parse_context._storage.add(obj)
-                return obj
-
-        for alias, symbol in symbol_table.table.items():
-            registrar = Registrar(parse_context, alias, object_type=symbol)
-            symbols[alias] = registrar
-
-        symbols.update(aliases.objects)
+                target_adaptor = TargetAdaptor(**kwargs)
+                self._parse_context._storage.add(target_adaptor)
+                return target_adaptor
 
-        for alias, object_factory in aliases.context_aware_object_factories.items():
+        symbols.update({alias: Registrar(parse_context, alias) for alias in target_type_aliases})
+        symbols.update(object_aliases.objects)
+        for alias, object_factory in object_aliases.context_aware_object_factories.items():
             symbols[alias] = object_factory(parse_context)
 
         return symbols, parse_context

src/python/pants/engine/internals/parser_test.py

@@ -4,13 +4,12 @@
 import pytest
 
 from pants.build_graph.build_file_aliases import BuildFileAliases
-from pants.engine.internals.parser import BuildFilePreludeSymbols, ParseError, Parser, SymbolTable
-from pants.engine.internals.target_adaptor import TargetAdaptor
+from pants.engine.internals.parser import BuildFilePreludeSymbols, ParseError, Parser
 from pants.util.frozendict import FrozenDict
 
 
 def test_imports_banned() -> None:
-    parser = Parser(SymbolTable({}), BuildFileAliases())
+    parser = Parser(target_type_aliases=[], object_aliases=BuildFileAliases())
     with pytest.raises(ParseError) as exc:
         parser.parse(
             "dir/BUILD", "\nx = 'hello'\n\nimport os\n", BuildFilePreludeSymbols(FrozenDict())
@@ -20,8 +19,8 @@ def test_imports_banned() -> None:
 
 def test_unrecognized_symbol() -> None:
     parser = Parser(
-        SymbolTable({"tgt": TargetAdaptor}),
-        BuildFileAliases(
+        target_type_aliases=["tgt"],
+        object_aliases=BuildFileAliases(
             objects={"obj": 0},
             context_aware_object_factories={"caof": lambda parse_context: lambda _: None},
         ),

src/python/pants/init/engine_initializer.py

@@ -19,10 +19,9 @@
 from pants.engine.internals.build_files import create_graph_rules
 from pants.engine.internals.mapper import AddressMapper
 from pants.engine.internals.native import Native
-from pants.engine.internals.parser import Parser, SymbolTable
+from pants.engine.internals.parser import Parser
 from pants.engine.internals.scheduler import Scheduler, SchedulerSession
 from pants.engine.internals.selectors import Params
-from pants.engine.internals.target_adaptor import TargetAdaptor
 from pants.engine.platform import create_platform_rules
 from pants.engine.process import InteractiveRunner
 from pants.engine.rules import RootRule, collect_rules, rule
@@ -246,10 +245,9 @@ def setup_legacy_graph_extended(
         union_membership = UnionMembership.from_rules(build_configuration.union_rules)
 
         registered_target_types = RegisteredTargetTypes.create(build_configuration.target_types)
-        symbol_table_from_registered_targets = SymbolTable(
-            {target_type.alias: TargetAdaptor for target_type in registered_target_types.types}
+        parser = Parser(
+            target_type_aliases=registered_target_types.aliases, object_aliases=build_file_aliases
         )
-        parser = Parser(symbol_table_from_registered_targets, build_file_aliases)
         address_mapper = AddressMapper(
             parser=parser,
             prelude_glob_patterns=build_file_prelude_globs,
@@ -266,10 +264,6 @@ def glob_match_error_behavior_singleton() -> GlobMatchErrorBehavior:
         def build_configuration_singleton() -> BuildConfiguration:
             return build_configuration
 
-        @rule
-        def symbol_table_singleton() -> SymbolTable:
-            return symbol_table_from_registered_targets
-
         @rule
         def registered_target_types_singleton() -> RegisteredTargetTypes:
             return registered_target_types