SERVER-31390 Use a templating language to generate error_codes.{h,cpp,js}

Author: RedBeard0531

.eslintignore

@@ -1 +1,2 @@
 src/mongo/gotools/*
+*.tpl.js

buildscripts/requirements.txt

@@ -10,3 +10,5 @@ pylint == 1.6.5
 pydocstyle == 1.1.1
 # resmoke.py
 -r resmokelib/requirements.txt
+# generate_error_codes.py
+cheetah3 == 3.0.0; python_version < "3"

src/mongo/base/SConscript

@@ -4,10 +4,29 @@ Import("env")
 
 env = env.Clone()
 
-generateErrorCodes = env.Command(
-    target=['error_codes.h', 'error_codes.cpp'],
-    source=['generate_error_codes.py', 'error_codes.err'],
-    action=['$PYTHON ${SOURCES[0]} cpp ${SOURCES[1]} --cpp-header=${TARGETS[0]} --cpp-source=${TARGETS[1]}'])
+
+# This needs to use its own env to tell scons to suppress scanning the .tpl.h and .tpl.cpp inputs
+# for #includes since they aren't directly preprocessed. Scons will still scan the generated files
+# to produce the correct implicit dependencies when they are compiled.
+env_for_error_codes = env.Clone()
+env_for_error_codes['SCANNERS'] = []
+generateErrorCodes = env_for_error_codes.Command(
+    target=[
+        'error_codes.h',
+        'error_codes.cpp'
+    ],
+    source=[
+        'generate_error_codes.py',
+        'error_codes.err',
+        'error_codes.tpl.h',
+        'error_codes.tpl.cpp',
+    ],
+    action=['$PYTHON ${SOURCES[0]} ${SOURCES[1]} '
+            '${SOURCES[2]}=${TARGETS[0]} '
+            '${SOURCES[3]}=${TARGETS[1]}'
+    ],
+)
+
 env.Alias('generated-sources', generateErrorCodes)
 
 env.CppUnitTest('base_test',

src/mongo/base/error_codes.tpl.cpp

@@ -0,0 +1,77 @@
+/**
+ *    Copyright 2017 MongoDB, Inc.
+ *
+ *    This program is free software: you can redistribute it and/or  modify
+ *    it under the terms of the GNU Affero General Public License, version 3,
+ *    as published by the Free Software Foundation.
+ *
+ *    This program is distributed in the hope that it will be useful,
+ *    but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *    GNU Affero General Public License for more details.
+ *
+ *    You should have received a copy of the GNU Affero General Public License
+ *    along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ *
+ *    As a special exception, the copyright holders give permission to link the
+ *    code of portions of this program with the OpenSSL library under certain
+ *    conditions as described in each individual source file and distribute
+ *    linked combinations including the program with the OpenSSL library. You
+ *    must comply with the GNU Affero General Public License in all respects
+ *    for all of the code used other than as permitted herein. If you modify
+ *    file(s) with this exception, you may extend this exception to your
+ *    version of the file(s), but you are not obligated to do so. If you do not
+ *    wish to do so, delete this exception statement from your version. If you
+ *    delete this exception statement from all source files in the program,
+ *    then also delete it in the license file.
+ */
+
+#include "mongo/platform/basic.h"
+
+#include "mongo/base/error_codes.h"
+
+#include "mongo/base/static_assert.h"
+#include "mongo/util/assert_util.h"
+#include "mongo/util/mongoutils/str.h"
+
+namespace mongo {
+
+MONGO_STATIC_ASSERT(sizeof(ErrorCodes::Error) == sizeof(int));
+
+std::string ErrorCodes::errorString(Error err) {
+    switch (err) {
+        //#for $ec in $codes
+        case $ec.name:
+            return "$ec.name";
+        //#end for
+        default:
+            return mongoutils::str::stream() << "Location" << int(err);
+    }
+}
+
+ErrorCodes::Error ErrorCodes::fromString(StringData name) {
+    //#for $ec in $codes
+    if (name == "$ec.name"_sd)
+        return $ec.name;
+    //#end for
+    return UnknownError;
+}
+
+std::ostream& operator<<(std::ostream& stream, ErrorCodes::Error code) {
+    return stream << ErrorCodes::errorString(code);
+}
+
+//#for $cat in $categories
+bool ErrorCodes::is${cat.name}(Error err) {
+    switch (err) {
+        //#for $code in $cat.codes
+        case $code:
+            return true;
+        //#end for
+        default:
+            return false;
+    }
+}
+//#end for
+
+}  // namespace mongo

src/mongo/base/error_codes.tpl.h

@@ -0,0 +1,82 @@
+/**
+ *    Copyright 2017 MongoDB, Inc.
+ *
+ *    This program is free software: you can redistribute it and/or  modify
+ *    it under the terms of the GNU Affero General Public License, version 3,
+ *    as published by the Free Software Foundation.
+ *
+ *    This program is distributed in the hope that it will be useful,
+ *    but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *    GNU Affero General Public License for more details.
+ *
+ *    You should have received a copy of the GNU Affero General Public License
+ *    along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ *
+ *    As a special exception, the copyright holders give permission to link the
+ *    code of portions of this program with the OpenSSL library under certain
+ *    conditions as described in each individual source file and distribute
+ *    linked combinations including the program with the OpenSSL library. You
+ *    must comply with the GNU Affero General Public License in all respects
+ *    for all of the code used other than as permitted herein. If you modify
+ *    file(s) with this exception, you may extend this exception to your
+ *    version of the file(s), but you are not obligated to do so. If you do not
+ *    wish to do so, delete this exception statement from your version. If you
+ *    delete this exception statement from all source files in the program,
+ *    then also delete it in the license file.
+ */
+
+#pragma once
+
+#include <cstdint>
+#include <iosfwd>
+#include <string>
+
+#include "mongo/base/string_data.h"
+
+namespace mongo {
+
+/**
+ * This is a generated class containing a table of error codes and their corresponding error
+ * strings. The class is derived from the definitions in src/mongo/base/error_codes.err file and the
+ * src/mongo/base/error_codes.tpl.h template.
+ *
+ * Do not update this file directly. Update src/mongo/base/error_codes.err instead.
+ */
+class ErrorCodes {
+public:
+    // Explicitly 32-bits wide so that non-symbolic values,
+    // like uassert codes, are valid.
+    enum Error : std::int32_t {
+        //#for $ec in $codes
+        $ec.name = $ec.code,
+        //#end for
+        MaxError
+    };
+
+    static std::string errorString(Error err);
+
+    /**
+     * Parses an Error from its "name".  Returns UnknownError if "name" is unrecognized.
+     *
+     * NOTE: Also returns UnknownError for the string "UnknownError".
+     */
+    static Error fromString(StringData name);
+
+    /**
+     * Casts an integer "code" to an Error.  Unrecognized codes are preserved, meaning
+     * that the result of a call to fromInt() may not be one of the values in the
+     * Error enumeration.
+     */
+    static Error fromInt(int code) {
+        return static_cast<Error>(code);
+    }
+
+    //#for $cat in $categories
+    static bool is${cat.name}(Error err);
+    //#end for
+};
+
+std::ostream& operator<<(std::ostream& stream, ErrorCodes::Error code);
+
+}  // namespace mongo