Templatize SkToXXX.

include/private/SkTFitsIn.h

 /*
  * Copyright 2013 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #ifndef SkTFitsIn_DEFINED
 #define SkTFitsIn_DEFINED
 
-#include "SkTypes.h"
-#include "SkTLogic.h"
+#include "../private/SkTLogic.h"
 #include <limits>
 #include <type_traits>
 
 namespace sktfitsin {
 namespace Private {
 
 /** SkTMux::type = (a && b) ? Both : (a) ? A : (b) ? B : Neither; */
 template <bool a, bool b, typename Both, typename A, typename B, typename Neither>
 struct SkTMux {
     using type = skstd::conditional_t<a, skstd::conditional_t<b, Both, A>,
                                          skstd::conditional_t<b, B, Neither>>;
 };
 
 /** SkTHasMoreDigits = (digits(A) >= digits(B)) ? true_type : false_type. */
-template<typename A, typename B> struct SkTHasMoreDigits
+template <typename A, typename B> struct SkTHasMoreDigits
     : skstd::bool_constant<std::numeric_limits<A>::digits >= std::numeric_limits<B>::digits>
 { };
 
 /** A high or low side predicate which is used when it is statically known
  *  that source values are in the range of the Destination.
  */
 template <typename S> struct SkTOutOfRange_False {
-    typedef std::false_type can_be_true;
-    typedef S source_type;
-    static bool apply(S s) {
+    using can_be_true = std::false_type;
+    using source_type = S;
+    static bool apply(S) {
         return false;
     }
 };
 
 /** A low side predicate which tests if the source value < Min(D).
  *  Assumes that Min(S) <= Min(D).
  */
 template <typename D, typename S> struct SkTOutOfRange_LT_MinD {
-    typedef std::true_type can_be_true;
-    typedef S source_type;
+    using can_be_true = std::true_type;
+    using source_type = S;
     static bool apply(S s) {
-        typedef SkTHasMoreDigits<S, D> precondition;
-        static_assert(precondition::value, "SkTOutOfRange_LT_MinD__minS_gt_minD");
+        using precondition = SkTHasMoreDigits<S, D>;
+        static_assert(precondition::value, "minS > minD");
 
         return s < static_cast<S>((std::numeric_limits<D>::min)());
     }
 };
 
 /** A low side predicate which tests if the source value is less than 0. */
 template <typename D, typename S> struct SkTOutOfRange_LT_Zero {
-    typedef std::true_type can_be_true;
-    typedef S source_type;
+    using can_be_true = std::true_type;
+    using source_type = S;
     static bool apply(S s) {
         return s < static_cast<S>(0);
     }
 };
 
 /** A high side predicate which tests if the source value > Max(D).
  *  Assumes that Max(S) >= Max(D).
  */
 template <typename D, typename S> struct SkTOutOfRange_GT_MaxD {
-    typedef std::true_type can_be_true;
-    typedef S source_type;
+    using can_be_true = std::true_type;
+    using source_type = S;
     static bool apply(S s) {
-        typedef SkTHasMoreDigits<S, D> precondition;
-        static_assert(precondition::value, "SkTOutOfRange_GT_MaxD__maxS_lt_maxD");
+        using precondition = SkTHasMoreDigits<S, D>;
+        static_assert(precondition::value, "maxS < maxD");
 
         return s > static_cast<S>((std::numeric_limits<D>::max)());
     }
 };
 
 /** Composes two SkTOutOfRange predicates.
  *  First checks OutOfRange_Low then, if in range, OutOfRange_High.
  */
-template<class OutOfRange_Low, class OutOfRange_High> struct SkTOutOfRange_Either {
-    typedef std::true_type can_be_true;
-    typedef typename OutOfRange_Low::source_type source_type;
+template <typename OutOfRange_Low, typename OutOfRange_High> struct SkTOutOfRange_Either {
+    using can_be_true = std::true_type;
+    using source_type = typename OutOfRange_Low::source_type;
     static bool apply(source_type s) {
         bool outOfRange = OutOfRange_Low::apply(s);
         if (!outOfRange) {
             outOfRange = OutOfRange_High::apply(s);
         }
         return outOfRange;
     }
 };
 
 /** SkTCombineOutOfRange::type is an SkTOutOfRange_XXX type which is the
  *  optimal combination of OutOfRange_Low and OutOfRange_High.
  */
-template<class OutOfRange_Low, class OutOfRange_High> struct SkTCombineOutOfRange {
-    typedef SkTOutOfRange_Either<OutOfRange_Low, OutOfRange_High> Both;
-    typedef SkTOutOfRange_False<typename OutOfRange_Low::source_type> Neither;
+template <typename OutOfRange_Low, typename OutOfRange_High> struct SkTCombineOutOfRange {
+    using Both = SkTOutOfRange_Either<OutOfRange_Low, OutOfRange_High>;
+    using Neither = SkTOutOfRange_False<typename OutOfRange_Low::source_type>;
 
-    typedef typename OutOfRange_Low::can_be_true apply_low;
-    typedef typename OutOfRange_High::can_be_true apply_high;
+    using apply_low = typename OutOfRange_Low::can_be_true;
+    using apply_high = typename OutOfRange_High::can_be_true;
 
-    typedef typename SkTMux<apply_low::value, apply_high::value,
-                            Both, OutOfRange_Low, OutOfRange_High, Neither>::type type;
+    using type = typename SkTMux<apply_low::value, apply_high::value,
+                                 Both, OutOfRange_Low, OutOfRange_High, Neither>::type;
 };
 
-template<typename D, typename S, class OutOfRange_Low, class OutOfRange_High>
+template <typename D, typename S, typename OutOfRange_Low, typename OutOfRange_High>
 struct SkTRangeChecker {
     /** This is the method which is called at runtime to do the range check. */
     static bool OutOfRange(S s) {
-        typedef typename SkTCombineOutOfRange<OutOfRange_Low, OutOfRange_High>::type Combined;
+        using Combined = typename SkTCombineOutOfRange<OutOfRange_Low, OutOfRange_High>::type;
         return Combined::apply(s);
     }
 };
 
 /** SkTFitsIn_Unsigned2Unsiged::type is an SkTRangeChecker with an OutOfRange(S s) method
  *  the implementation of which is tailored for the source and destination types.
  *  Assumes that S and D are unsigned integer types.
  */
-template<typename D, typename S> struct SkTFitsIn_Unsigned2Unsiged {
-    typedef SkTOutOfRange_False<S> OutOfRange_Low;
-    typedef SkTOutOfRange_GT_MaxD<D, S> OutOfRange_High;
+template <typename D, typename S> struct SkTFitsIn_Unsigned2Unsiged {
+    using OutOfRange_Low = SkTOutOfRange_False<S>;
+    using OutOfRange_High = SkTOutOfRange_GT_MaxD<D, S>;
 
-    typedef SkTRangeChecker<D, S, OutOfRange_Low, OutOfRange_High> HighSideOnlyCheck;
-    typedef SkTRangeChecker<D, S, SkTOutOfRange_False<S>, SkTOutOfRange_False<S> > NoCheck;
+    using HighSideOnlyCheck = SkTRangeChecker<D, S, OutOfRange_Low, OutOfRange_High>;
+    using NoCheck = SkTRangeChecker<D, S, SkTOutOfRange_False<S>, SkTOutOfRange_False<S>>;
 
     // If std::numeric_limits<D>::digits >= std::numeric_limits<S>::digits, nothing to check.
     // This also protects the precondition of SkTOutOfRange_GT_MaxD.
-    typedef SkTHasMoreDigits<D, S> sourceFitsInDesitination;
-    typedef skstd::conditional_t<sourceFitsInDesitination::value, NoCheck, HighSideOnlyCheck> type;
+    using sourceFitsInDesitination = SkTHasMoreDigits<D, S>;
+    using type = skstd::conditional_t<sourceFitsInDesitination::value, NoCheck, HighSideOnlyCheck>;
 };
 
 /** SkTFitsIn_Signed2Signed::type is an SkTRangeChecker with an OutOfRange(S s) method
  *  the implementation of which is tailored for the source and destination types.
  *  Assumes that S and D are signed integer types.
  */
-template<typename D, typename S> struct SkTFitsIn_Signed2Signed {
-    typedef SkTOutOfRange_LT_MinD<D, S> OutOfRange_Low;
-    typedef SkTOutOfRange_GT_MaxD<D, S> OutOfRange_High;
+template <typename D, typename S> struct SkTFitsIn_Signed2Signed {
+    using OutOfRange_Low = SkTOutOfRange_LT_MinD<D, S>;
+    using OutOfRange_High = SkTOutOfRange_GT_MaxD<D, S>;
 
-    typedef SkTRangeChecker<D, S, OutOfRange_Low, OutOfRange_High> FullCheck;
-    typedef SkTRangeChecker<D, S, SkTOutOfRange_False<S>, SkTOutOfRange_False<S> > NoCheck;
+    using FullCheck = SkTRangeChecker<D, S, OutOfRange_Low, OutOfRange_High>;
+    using NoCheck = SkTRangeChecker<D, S, SkTOutOfRange_False<S>, SkTOutOfRange_False<S>>;
 
     // If std::numeric_limits<D>::digits >= std::numeric_limits<S>::digits, nothing to check.
     // This also protects the precondition of SkTOutOfRange_LT_MinD and SkTOutOfRange_GT_MaxD.
-    typedef SkTHasMoreDigits<D, S> sourceFitsInDesitination;
-    typedef skstd::conditional_t<sourceFitsInDesitination::value, NoCheck, FullCheck> type;
+    using sourceFitsInDesitination = SkTHasMoreDigits<D, S>;
+    using type = skstd::conditional_t<sourceFitsInDesitination::value, NoCheck, FullCheck>;
 };
 
 /** SkTFitsIn_Signed2Unsigned::type is an SkTRangeChecker with an OutOfRange(S s) method
  *  the implementation of which is tailored for the source and destination types.
  *  Assumes that S is a signed integer type and D is an unsigned integer type.
  */
-template<typename D, typename S> struct SkTFitsIn_Signed2Unsigned {
-    typedef SkTOutOfRange_LT_Zero<D, S> OutOfRange_Low;
-    typedef SkTOutOfRange_GT_MaxD<D, S> OutOfRange_High;
+template <typename D, typename S> struct SkTFitsIn_Signed2Unsigned {
+    using OutOfRange_Low = SkTOutOfRange_LT_Zero<D, S>;
+    using OutOfRange_High = SkTOutOfRange_GT_MaxD<D, S>;
 
-    typedef SkTRangeChecker<D, S, OutOfRange_Low, OutOfRange_High> FullCheck;
-    typedef SkTRangeChecker<D, S, OutOfRange_Low, SkTOutOfRange_False<S> > LowSideOnlyCheck;
+    using FullCheck = SkTRangeChecker<D, S, OutOfRange_Low, OutOfRange_High>;
+    using LowSideOnlyCheck = SkTRangeChecker<D, S, OutOfRange_Low, SkTOutOfRange_False<S>>;
 
     // If std::numeric_limits<D>::max() >= std::numeric_limits<S>::max(),
     // no need to check the high side. (Until C++11, assume more digits means greater max.)
     // This also protects the precondition of SkTOutOfRange_GT_MaxD.
-    typedef SkTHasMoreDigits<D, S> sourceCannotExceedDest;
-    typedef skstd::conditional_t<sourceCannotExceedDest::value, LowSideOnlyCheck, FullCheck> type;
+    using sourceCannotExceedDest = SkTHasMoreDigits<D, S>;
+    using type = skstd::conditional_t<sourceCannotExceedDest::value, LowSideOnlyCheck, FullCheck>;
 };
 
 /** SkTFitsIn_Unsigned2Signed::type is an SkTRangeChecker with an OutOfRange(S s) method
  *  the implementation of which is tailored for the source and destination types.
  *  Assumes that S is an usigned integer type and D is a signed integer type.
  */
-template<typename D, typename S> struct SkTFitsIn_Unsigned2Signed {
-    typedef SkTOutOfRange_False<S> OutOfRange_Low;
-    typedef SkTOutOfRange_GT_MaxD<D, S> OutOfRange_High;
+template <typename D, typename S> struct SkTFitsIn_Unsigned2Signed {
+    using OutOfRange_Low = SkTOutOfRange_False<S>;
+    using OutOfRange_High = SkTOutOfRange_GT_MaxD<D, S>;
 
-    typedef SkTRangeChecker<D, S, OutOfRange_Low, OutOfRange_High> HighSideOnlyCheck;
-    typedef SkTRangeChecker<D, S, SkTOutOfRange_False<S>, SkTOutOfRange_False<S> > NoCheck;
+    using HighSideOnlyCheck = SkTRangeChecker<D, S, OutOfRange_Low, OutOfRange_High>;
+    using NoCheck = SkTRangeChecker<D, S, SkTOutOfRange_False<S>, SkTOutOfRange_False<S>>;
 
     // If std::numeric_limits<D>::max() >= std::numeric_limits<S>::max(), nothing to check.
     // (Until C++11, assume more digits means greater max.)
     // This also protects the precondition of SkTOutOfRange_GT_MaxD.
-    typedef SkTHasMoreDigits<D, S> sourceCannotExceedDest;
-    typedef skstd::conditional_t<sourceCannotExceedDest::value, NoCheck, HighSideOnlyCheck> type;
+    using sourceCannotExceedDest = SkTHasMoreDigits<D, S>;
+    using type = skstd::conditional_t<sourceCannotExceedDest::value, NoCheck, HighSideOnlyCheck>;
 };
 
 /** SkTFitsIn::type is an SkTRangeChecker with an OutOfRange(S s) method
  *  the implementation of which is tailored for the source and destination types.
  *  Assumes that S and D are integer types.
  */
-template<typename D, typename S> struct SkTFitsIn {
+template <typename D, typename S> struct SkTFitsIn {
     // One of the following will be the 'selector' type.
-    typedef SkTFitsIn_Signed2Signed<D, S> S2S;
-    typedef SkTFitsIn_Signed2Unsigned<D, S> S2U;
-    typedef SkTFitsIn_Unsigned2Signed<D, S> U2S;
-    typedef SkTFitsIn_Unsigned2Unsiged<D, S> U2U;
+    using S2S = SkTFitsIn_Signed2Signed<D, S>;
+    using S2U = SkTFitsIn_Signed2Unsigned<D, S>;
+    using U2S = SkTFitsIn_Unsigned2Signed<D, S>;
+    using U2U = SkTFitsIn_Unsigned2Unsiged<D, S>;
 
-    typedef skstd::bool_constant<std::numeric_limits<S>::is_signed> S_is_signed;
-    typedef skstd::bool_constant<std::numeric_limits<D>::is_signed> D_is_signed;
+    using S_is_signed = skstd::bool_constant<std::numeric_limits<S>::is_signed>;
+    using D_is_signed = skstd::bool_constant<std::numeric_limits<D>::is_signed>;
 
-    typedef typename SkTMux<S_is_signed::value, D_is_signed::value,
-                            S2S, S2U, U2S, U2U>::type selector;
+    using selector = typename SkTMux<S_is_signed::value, D_is_signed::value,
+                                     S2S, S2U, U2S, U2U>::type;
     // This type is an SkTRangeChecker.
-    typedef typename selector::type type;
+    using type = typename selector::type;
+};
+
+template <typename T, bool = std::is_enum<T>::value> struct underlying_type {
+    using type = skstd::underlying_type_t<T>;
+};
+template <typename T> struct underlying_type<T, false> {
+    using type = T;
 };
 
 } // namespace Private
 } // namespace sktfitsin
 
 /** Returns true if the integer source value 's' will fit in the integer destination type 'D'. */
 template <typename D, typename S> inline bool SkTFitsIn(S s) {
-    static_assert(std::numeric_limits<S>::is_integer, "SkTFitsIn_source_must_be_integer");
-    static_assert(std::numeric_limits<D>::is_integer, "SkTFitsIn_destination_must_be_integer");
+    static_assert(std::is_integral<S>::value || std::is_enum<S>::value, "S must be integral.");
+    static_assert(std::is_integral<D>::value || std::is_enum<D>::value, "D must be integral.");
 
-    return !sktfitsin::Private::SkTFitsIn<D, S>::type::OutOfRange(s);
+    using RealS = typename sktfitsin::Private::underlying_type<S>::type;
+    using RealD = typename sktfitsin::Private::underlying_type<D>::type;
+
+    return !sktfitsin::Private::SkTFitsIn<RealD, RealS>::type::OutOfRange(s);
 }
 
 #endif