THRIFT-1500: d programming language support
Client: D
Patch: David Nadlinger
D program language library and additions
git-svn-id: https://svn.apache.org/repos/asf/thrift/trunk@1304085 13f79535-47bb-0310-9956-ffa450edef68
diff --git a/lib/d/src/thrift/internal/traits.d b/lib/d/src/thrift/internal/traits.d
new file mode 100644
index 0000000..11e98c5
--- /dev/null
+++ b/lib/d/src/thrift/internal/traits.d
@@ -0,0 +1,141 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements. See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership. The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License. You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied. See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
+module thrift.internal.traits;
+
+import std.traits;
+
+/**
+ * Adds or removes attributes from the given function (pointer) or delegate
+ * type.
+ *
+ * Besides the base type, two std.traits.FunctionAttribute bitfields are
+ * accepted, representing the attributes to add to the function signature
+ * resp. to remove from it. If an attribute appears in both fields, an error
+ * is raised.
+ *
+ * Params:
+ * T = The base type.
+ * setAttrs = The attributes to add to the type, if not already present.
+ * clearAttrs = The attributes to remove from the type, if present.
+ */
+template ChangeFuncAttrs(
+ T,
+ FunctionAttribute setAttrs = FunctionAttribute.none,
+ FunctionAttribute clearAttrs = FunctionAttribute.none
+) if (isFunctionPointer!T || isDelegate!T) {
+ static assert(!(setAttrs & clearAttrs),
+ "Cannot set and clear attributes at the same time.");
+ mixin({
+ enum newAttrs = (functionAttributes!T | setAttrs) & ~clearAttrs;
+ static assert(!(newAttrs & FunctionAttribute.trusted) ||
+ !(newAttrs & FunctionAttribute.safe),
+ "Cannot have a function/delegate that is both trusted and safe.");
+
+ string result = "alias ";
+
+ static if (functionLinkage!T != "D") {
+ result ~= "extern(" ~ functionLinkage!T ~ ") ";
+ }
+
+ static if (newAttrs & FunctionAttribute.ref_) {
+ result ~= "ref ";
+ }
+
+ result ~= "ReturnType!T";
+
+ static if (isDelegate!T) {
+ result ~= " delegate";
+ } else {
+ result ~= " function";
+ }
+
+ result ~= "(ParameterTypeTuple!T)";
+
+ static if (newAttrs & FunctionAttribute.pure_) {
+ result ~= " pure";
+ }
+ static if (newAttrs & FunctionAttribute.nothrow_) {
+ result ~= " nothrow";
+ }
+ static if (newAttrs & FunctionAttribute.property) {
+ result ~= " @property";
+ }
+ static if (newAttrs & FunctionAttribute.trusted) {
+ result ~= " @trusted";
+ }
+ static if (newAttrs & FunctionAttribute.safe) {
+ result ~= " @safe";
+ }
+
+ result ~= " ChangeFuncAttrs;";
+ return result;
+ }());
+}
+
+/// Ditto
+template ChangeFuncAttrs(
+ T,
+ FunctionAttribute setAttrs = FunctionAttribute.none,
+ FunctionAttribute clearAttrs = FunctionAttribute.none
+) if (is(T == function)) {
+ // To avoid a lot of syntactic headaches, we just use the above version to
+ // operate on the corresponding function pointer type and then remove the
+ // pointer again.
+ alias FunctionTypeOf!(ChangeFuncAttrs!(T*, setAttrs, clearAttrs))
+ ChangeFuncAttrs;
+}
+
+version (unittest) {
+ import std.algorithm;
+ import std.metastrings;
+ import std.typetuple;
+}
+unittest {
+ alias FunctionAttribute FA;
+ foreach (T0; TypeTuple!(
+ int function(int),
+ int delegate(int),
+ FunctionTypeOf!(int function(int))
+ )) {
+ alias ChangeFuncAttrs!(T0, FA.safe) T1;
+ static assert(functionAttributes!T1 == FA.safe);
+
+ alias ChangeFuncAttrs!(T1, FA.nothrow_ | FA.ref_, FA.safe) T2;
+ static assert(functionAttributes!T2 == (FA.nothrow_ | FA.ref_));
+
+ enum allAttrs = reduce!"a | b"([EnumMembers!FA]) & ~FA.safe;
+
+ alias ChangeFuncAttrs!(T2, allAttrs) T3;
+ static assert(functionAttributes!T3 == allAttrs);
+
+ alias ChangeFuncAttrs!(T3, FA.none, allAttrs) T4;
+ static assert(is(T4 == T0));
+ }
+}
+
+/**
+ * Adds »nothrow« to the type of the passed function pointer/delegate, if it
+ * is not already present.
+ *
+ * Technically, assumeNothrow just performs a cast, but using it has the
+ * advantage of being explicitly about the operation that is performed.
+ */
+auto assumeNothrow(T)(T t) if (isFunctionPointer!T || isDelegate!T) {
+ return cast(ChangeFuncAttrs!(T, FunctionAttribute.nothrow_))t;
+}