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Unified Diff: third_party/cld/base/template_util.h

Issue 122007: [chromium-reviews] Add Compact Language Detection (CLD) library to Chrome. This works in Windows... (Closed) Base URL: svn://chrome-svn/chrome/trunk/src/
Patch Set: '' Created 11 years, 6 months ago
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Index: third_party/cld/base/template_util.h
===================================================================
--- third_party/cld/base/template_util.h (revision 0)
+++ third_party/cld/base/template_util.h (revision 0)
@@ -0,0 +1,96 @@
+// Copyright (c) 2006-2009 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+// Template metaprogramming utility functions.
+//
+// This code is compiled directly on many platforms, including client
+// platforms like Windows, Mac, and embedded systems. Before making
+// any changes here, make sure that you're not breaking any platforms.
+//
+// The names choosen here reflect those used in tr1 and the boost::mpl
+// library, there are similar operations used in the Loki library as
+// well. I prefer the boost names for 2 reasons:
+// 1. I think that portions of the Boost libraries are more likely to
+// be included in the c++ standard.
+// 2. It is not impossible that some of the boost libraries will be
+// included in our own build in the future.
+// Both of these outcomes means that we may be able to directly replace
+// some of these with boost equivalents.
+//
+#ifndef BASE_TEMPLATE_UTIL_H_
+#define BASE_TEMPLATE_UTIL_H_
+
+namespace base {
+
+// Types small_ and big_ are guaranteed such that sizeof(small_) <
+// sizeof(big_)
+typedef char small_;
+
+struct big_ {
+ char dummy[2];
+};
+
+// integral_constant, defined in tr1, is a wrapper for an integer
+// value. We don't really need this generality; we could get away
+// with hardcoding the integer type to bool. We use the fully
+// general integer_constant for compatibility with tr1.
+
+template<class T, T v>
+struct integral_constant {
+ static const T value = v;
+ typedef T value_type;
+ typedef integral_constant<T, v> type;
+};
+
+template <class T, T v> const T integral_constant<T, v>::value;
+
+
+// Abbreviations: true_type and false_type are structs that represent boolean
+// true and false values. Also define the boost::mpl versions of those names,
+// true_ and false_.
+typedef integral_constant<bool, true> true_type;
+typedef integral_constant<bool, false> false_type;
+typedef true_type true_;
+typedef false_type false_;
+
+// if_ is a templatized conditional statement.
+// if_<cond, A, B> is a compile time evaluation of cond.
+// if_<>::type contains A if cond is true, B otherwise.
+template<bool cond, typename A, typename B>
+struct if_{
+ typedef A type;
+};
+
+template<typename A, typename B>
+struct if_<false, A, B> {
+ typedef B type;
+};
+
+
+// type_equals_ is a template type comparator, similar to Loki IsSameType.
+// type_equals_<A, B>::value is true iff "A" is the same type as "B".
+template<typename A, typename B>
+struct type_equals_ : public false_ {
+};
+
+template<typename A>
+struct type_equals_<A, A> : public true_ {
+};
+
+// and_ is a template && operator.
+// and_<A, B>::value evaluates "A::value && B::value".
+template<typename A, typename B>
+struct and_ : public integral_constant<bool, (A::value && B::value)> {
+};
+
+// or_ is a template || operator.
+// or_<A, B>::value evaluates "A::value || B::value".
+template<typename A, typename B>
+struct or_ : public integral_constant<bool, (A::value || B::value)> {
+};
+
+
+} // Close namespace base
+
+#endif // BASE_TEMPLATE_UTIL_H_
Property changes on: third_party\cld\base\template_util.h
___________________________________________________________________
Added: svn:eol-style
+ LF
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