SERVER-51862 Generate a C++ base class for each V1 command

5 files changed, 91 insertions, 28 deletions

diff --git a/buildscripts/idl/idl/ast.py b/buildscripts/idl/idl/ast.py
index 1d0b97a1f82..7ae0a3c7f33 100644
--- a/buildscripts/idl/idl/ast.py
+++ b/buildscripts/idl/idl/ast.py
@@ -215,6 +215,7 @@ class Command(Struct):
         # type: (str, int, int) -> None
         """Construct a command."""
         self.namespace = None  # type: str
+        self.command_name = None  # type: str
         self.command_field = None  # type: Field
         self.reply_type = None  # type: Field
         self.api_version = ""  # type: str
@@ -268,8 +269,6 @@ class FieldListEntry(common.SourceLocation):
         self.name = None  # type: str
         self.forward_to_shards = False  # type: bool
         self.forward_from_shards = False  # type: bool
-
-        self.command_name = None  # type: str
         super(FieldListEntry, self).__init__(file_name, line, column)
 
     def get_should_forward(self):
diff --git a/buildscripts/idl/idl/binder.py b/buildscripts/idl/idl/binder.py
index 20eebf0158c..b449c962add 100644
--- a/buildscripts/idl/idl/binder.py
+++ b/buildscripts/idl/idl/binder.py
@@ -482,6 +482,8 @@ def _bind_command_reply_type(ctxt, parsed_spec, command):
 
     if not isinstance(syntax_symbol, syntax.Struct):
         ctxt.add_reply_type_invalid_type(ast_field, command.name, command.reply_type)
+    else:
+        ast_field.struct_type = syntax_symbol.name
 
     return ast_field
 
@@ -497,6 +499,8 @@ def _bind_command(ctxt, parsed_spec, command):
 
     ast_command = ast.Command(command.file_name, command.line, command.column)
     ast_command.api_version = command.api_version
+    ast_command.is_deprecated = command.is_deprecated
+    ast_command.command_name = command.command_name
 
     # Inject special fields used for command parsing
     _inject_hidden_command_fields(command)
diff --git a/buildscripts/idl/idl/generator.py b/buildscripts/idl/idl/generator.py
index 36c8976e7c6..71667f94539 100644
--- a/buildscripts/idl/idl/generator.py
+++ b/buildscripts/idl/idl/generator.py
@@ -514,6 +514,8 @@ class _CppFileWriterBase(object):
 class _CppHeaderFileWriter(_CppFileWriterBase):
     """C++ .h File writer."""
 
+    # pylint: disable=too-many-public-methods
+
     def gen_class_declaration_block(self, class_name):
         # type: (str) -> writer.IndentedScopedBlock
         """Generate a class declaration block."""
@@ -715,8 +717,8 @@ class _CppHeaderFileWriter(_CppFileWriterBase):
 
         if isinstance(struct, ast.Command):
             self._writer.write_line(
-                common.template_args('static constexpr auto kCommandName = "${struct_name}"_sd;',
-                                     struct_name=struct.name))
+                common.template_args('static constexpr auto kCommandName = "${command_name}"_sd;',
+                                     command_name=struct.command_name))
 
     def gen_enum_functions(self, idl_enum):
         # type: (ast.Enum) -> None
@@ -910,6 +912,76 @@ class _CppHeaderFileWriter(_CppFileWriterBase):
 
         self.write_empty_line()
 
+    def gen_template_declaration(self):
+        # type: () -> None
+        """Generate a template declaration for a command's base class."""
+        self._writer.write_line('template <typename Derived>')
+
+    def gen_derived_class_declaration_block(self, command_name, api_version):
+        # type: (str, str) -> writer.IndentedScopedBlock
+        """Generate a command's base class declaration block."""
+        class_name = common.title_case(command_name) + "CmdVersion" + api_version + "Gen"
+        return writer.IndentedScopedBlock(
+            self._writer, 'class %s : public TypedCommand<Derived> {' % class_name, '};')
+
+    def gen_type_alias_declaration(self, new_type_name, old_type_name):
+        # type: (str, str) -> None
+        """Generate a type alias declaration."""
+        self._writer.write_line(
+            'using %s = %s;' % (new_type_name, common.title_case(old_type_name)))
+
+    def gen_api_version_fn(self, is_api_versions, api_version):
+        # type: (bool, Union[str, bool]) -> None
+        """Generate an apiVersions or deprecatedApiVersions function for a command's base class."""
+        fn_name = "apiVersions" if is_api_versions else "deprecatedApiVersions"
+        fn_def = 'virtual const std::set<std::string>& %s() const override' % fn_name
+        value = "kApiVersions1" if api_version else "kNoApiVersions"
+        with self._block('%s {' % (fn_def), '}'):
+            self._writer.write_line('return %s;' % value)
+
+    def gen_invocation_base_class_declaration(self):
+        # type: () -> None
+        """Generate the InvocationBaseGen class for a command's base class."""
+        class_declaration = 'class InvocationBaseGen : public _TypedCommandInvocationBase {'
+        with writer.IndentedScopedBlock(self._writer, class_declaration, '};'):
+            # public requires special indentation that aligns with the class definition.
+            self._writer.unindent()
+            self._writer.write_line('public:')
+            self._writer.indent()
+
+            # Inherit base constructor.
+            self._writer.write_line(
+                'using _TypedCommandInvocationBase::_TypedCommandInvocationBase;')
+
+            self._writer.write_line('virtual Reply typedRun(OperationContext* opCtx) = 0;')
+
+    def generate_versioned_command_base_class(self, command):
+        # type: (ast.Command) -> None
+        """Generate a command's C++ base class to a stream."""
+        self.write_empty_line()
+
+        self.gen_template_declaration()
+
+        with self.gen_derived_class_declaration_block(command.command_name, command.api_version):
+            # Write type alias for InvocationBase.
+            self.gen_type_alias_declaration('_TypedCommandInvocationBase',
+                                            'typename TypedCommand<Derived>::InvocationBase')
+
+            self.write_empty_line()
+
+            self.write_unindented_line('public:')
+
+            # Write type aliases for Request and Reply.
+            self.gen_type_alias_declaration("Request", command.command_name)
+            self.gen_type_alias_declaration("Reply", command.reply_type.struct_type)
+
+            # Write apiVersions() and deprecatedApiVersions() functions.
+            self.gen_api_version_fn(True, command.api_version)
+            self.gen_api_version_fn(False, command.is_deprecated)
+
+            # Write InvocationBaseGen class.
+            self.gen_invocation_base_class_declaration()
+
     def generate(self, spec):
         # type: (ast.IDLAST) -> None
         """Generate the C++ header to a stream."""
@@ -961,6 +1033,11 @@ class _CppHeaderFileWriter(_CppFileWriterBase):
             header_list.append('mongo/idl/server_parameter.h')
             header_list.append('mongo/idl/server_parameter_with_storage.h')
 
+        # Include this for TypedCommand only if a base class will be generated for a command in this
+        # file.
+        if any(command.api_version for command in spec.commands):
+            header_list.append('mongo/db/commands.h')
+
         header_list.sort()
 
         for include in header_list:
@@ -968,7 +1045,7 @@ class _CppHeaderFileWriter(_CppFileWriterBase):
 
         self.write_empty_line()
 
-        # Generate namesapce
+        # Generate namespace
         with self.gen_namespace_block(spec.globals.cpp_namespace):
             self.write_empty_line()
 
@@ -1077,6 +1154,11 @@ class _CppHeaderFileWriter(_CppFileWriterBase):
                     self._gen_extern_declaration(opt.cpp_vartype, opt.cpp_varname, opt.condition)
                 self._gen_config_function_declaration(spec)
 
+            # Write a base class for each command in API Version 1.
+            for command in spec.commands:
+                if command.api_version:
+                    self.generate_versioned_command_base_class(command)
+
 
 class _CppSourceFileWriter(_CppFileWriterBase):
     """C++ .cpp File writer."""
@@ -2314,7 +2396,7 @@ class _CppSourceFileWriter(_CppFileWriterBase):
 
     def generate(self, spec, header_file_name):
         # type: (ast.IDLAST, str) -> None
-        """Generate the C++ header to a stream."""
+        """Generate the C++ source to a stream."""
 
         # pylint: disable=too-many-statements
 
diff --git a/buildscripts/idl/idl/syntax.py b/buildscripts/idl/idl/syntax.py
index a249bf235b7..fcacc571139 100644
--- a/buildscripts/idl/idl/syntax.py
+++ b/buildscripts/idl/idl/syntax.py
@@ -475,7 +475,6 @@ class FieldListEntry(common.SourceLocation):
         self.name = None  # type: str
         self.forward_to_shards = False  # type: bool
         self.forward_from_shards = False  # type: bool
-        self.command_name = None  # type: str
         super(FieldListEntry, self).__init__(file_name, line, column)
 
 
diff --git a/src/mongo/db/commands/generic.cpp b/src/mongo/db/commands/generic.cpp
index 4c3bc4ca914..52ed0d5c556 100644
--- a/src/mongo/db/commands/generic.cpp
+++ b/src/mongo/db/commands/generic.cpp
@@ -52,27 +52,6 @@ using std::string;
 using std::stringstream;
 using std::vector;
 
-// TODO (SERVER-51862): generate PingCmdVersion1Gen from IDL.
-template <typename Derived>
-class PingCmdVersion1Gen : public TypedCommand<Derived> {
-    using _TypedCommandInvocationBase = typename TypedCommand<Derived>::InvocationBase;
-
-public:
-    using Request = Ping;
-    using Reply = OkReply;
-    virtual const std::set<std::string>& apiVersions() const override {
-        return kApiVersions1;
-    }
-    virtual const std::set<std::string>& deprecatedApiVersions() const override {
-        return kNoApiVersions;
-    }
-    class InvocationBaseGen : public _TypedCommandInvocationBase {
-    public:
-        using _TypedCommandInvocationBase::_TypedCommandInvocationBase;
-        virtual Reply typedRun(OperationContext* opCtx) = 0;
-    };
-};
-
 class PingCommand : public PingCmdVersion1Gen<PingCommand> {
 public:
     AllowedOnSecondary secondaryAllowed(ServiceContext*) const override {