Add a generic collection of class templates to ADT for building

variadic-like functions in C++98. See the comments in the header file
for a more detailed description of how these work. We plan to use these
extensively in the AST matching library. This code and idea were
originally authored by Zhanyong Wan. I've condensed it using macros
to reduce repeatition and adjusted it to fit better with LLVM's ADT.

Thanks to both David Blaikie and Doug Gregor for the review!

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@146729 91177308-0d34-0410-b5e6-96231b3b80d8

diff --git a/include/llvm/ADT/VariadicFunction.h b/include/llvm/ADT/VariadicFunction.h
new file mode 100644 (file)
index 0000000..08c9697
--- /dev/null
+++ b/include/llvm/ADT/VariadicFunction.h
@@ -0,0 +1,343 @@
+//===--- VariadicFunctions.h - Variadic Functions ---------------*- C++ -*-===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+//  This file implements compile-time type-safe variadic functions.
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_ADT_VARIADIC_FUNCTION_H
+#define LLVM_ADT_VARIADIC_FUNCTION_H
+
+#include "llvm/ADT/ArrayRef.h"
+
+namespace llvm {
+
+// Define macros to aid in expanding a comma separated series with the index of
+// the series pasted onto the last token.
+#define LLVM_COMMA_JOIN1(x) x ## 0
+#define LLVM_COMMA_JOIN2(x) LLVM_COMMA_JOIN1(x), x ## 1
+#define LLVM_COMMA_JOIN3(x) LLVM_COMMA_JOIN2(x), x ## 2
+#define LLVM_COMMA_JOIN4(x) LLVM_COMMA_JOIN3(x), x ## 3
+#define LLVM_COMMA_JOIN5(x) LLVM_COMMA_JOIN4(x), x ## 4
+#define LLVM_COMMA_JOIN6(x) LLVM_COMMA_JOIN5(x), x ## 5
+#define LLVM_COMMA_JOIN7(x) LLVM_COMMA_JOIN6(x), x ## 6
+#define LLVM_COMMA_JOIN8(x) LLVM_COMMA_JOIN7(x), x ## 7
+#define LLVM_COMMA_JOIN9(x) LLVM_COMMA_JOIN8(x), x ## 8
+#define LLVM_COMMA_JOIN10(x) LLVM_COMMA_JOIN9(x), x ## 9
+#define LLVM_COMMA_JOIN11(x) LLVM_COMMA_JOIN10(x), x ## 10
+#define LLVM_COMMA_JOIN12(x) LLVM_COMMA_JOIN11(x), x ## 11
+#define LLVM_COMMA_JOIN13(x) LLVM_COMMA_JOIN12(x), x ## 12
+#define LLVM_COMMA_JOIN14(x) LLVM_COMMA_JOIN13(x), x ## 13
+#define LLVM_COMMA_JOIN15(x) LLVM_COMMA_JOIN14(x), x ## 14
+#define LLVM_COMMA_JOIN16(x) LLVM_COMMA_JOIN15(x), x ## 15
+#define LLVM_COMMA_JOIN17(x) LLVM_COMMA_JOIN16(x), x ## 16
+#define LLVM_COMMA_JOIN18(x) LLVM_COMMA_JOIN17(x), x ## 17
+#define LLVM_COMMA_JOIN19(x) LLVM_COMMA_JOIN18(x), x ## 18
+#define LLVM_COMMA_JOIN20(x) LLVM_COMMA_JOIN19(x), x ## 19
+#define LLVM_COMMA_JOIN21(x) LLVM_COMMA_JOIN20(x), x ## 20
+#define LLVM_COMMA_JOIN22(x) LLVM_COMMA_JOIN21(x), x ## 21
+#define LLVM_COMMA_JOIN23(x) LLVM_COMMA_JOIN22(x), x ## 22
+#define LLVM_COMMA_JOIN24(x) LLVM_COMMA_JOIN23(x), x ## 23
+#define LLVM_COMMA_JOIN25(x) LLVM_COMMA_JOIN24(x), x ## 24
+#define LLVM_COMMA_JOIN26(x) LLVM_COMMA_JOIN25(x), x ## 25
+#define LLVM_COMMA_JOIN27(x) LLVM_COMMA_JOIN26(x), x ## 26
+#define LLVM_COMMA_JOIN28(x) LLVM_COMMA_JOIN27(x), x ## 27
+#define LLVM_COMMA_JOIN29(x) LLVM_COMMA_JOIN28(x), x ## 28
+#define LLVM_COMMA_JOIN30(x) LLVM_COMMA_JOIN29(x), x ## 29
+#define LLVM_COMMA_JOIN31(x) LLVM_COMMA_JOIN30(x), x ## 30
+#define LLVM_COMMA_JOIN32(x) LLVM_COMMA_JOIN31(x), x ## 31
+
+/// \brief Class which can simulate a type-safe variadic function.
+///
+/// The VariadicFunction class template makes it easy to define
+/// type-safe variadic functions where all arguments have the same
+/// type.
+///
+/// Suppose we need a variadic function like this:
+///
+///   ResultT Foo(const ArgT &A_0, const ArgT &A_1, ..., const ArgT &A_N);
+///
+/// Instead of many overloads of Foo(), we only need to define a helper
+/// function that takes an array of arguments:
+///
+///   ResultT FooImpl(ArrayRef<const ArgT *> Args) {
+///     // 'Args[i]' is a pointer to the i-th argument passed to Foo().
+///     ...
+///   }
+///
+/// and then define Foo() like this:
+///
+///   const VariadicFunction<ResultT, ArgT, FooImpl> Foo;
+///
+/// VariadicFunction takes care of defining the overloads of Foo().
+///
+/// Actually, Foo is a function object (i.e. functor) instead of a plain
+/// function.  This object is stateless and its constructor/destructor
+/// does nothing, so it's safe to create global objects and call Foo(...) at
+/// any time.
+///
+/// Sometimes we need a variadic function to have some fixed leading
+/// arguments whose types may be different from that of the optional
+/// arguments.  For example:
+///
+///   bool FullMatch(const StringRef &S, const RE &Regex,
+///                  const ArgT &A_0, ..., const ArgT &A_N);
+///
+/// VariadicFunctionN is for such cases, where N is the number of fixed
+/// arguments.  It is like VariadicFunction, except that it takes N more
+/// template arguments for the types of the fixed arguments:
+///
+///   bool FullMatchImpl(const StringRef &S, const RE &Regex,
+///                      ArrayRef<const ArgT *> Args) { ... }
+///   const VariadicFunction2<bool, const StringRef&,
+///                           const RE&, ArgT, FullMatchImpl>
+///       FullMatch;
+///
+/// Currently VariadicFunction and friends support up-to 3
+/// fixed leading arguments and up-to 32 optional arguments.
+template <typename ResultT, typename ArgT,
+          ResultT (*Func)(ArrayRef<const ArgT *>)>
+class VariadicFunction {
+ public:
+  VariadicFunction() {}
+
+  ResultT operator()() const {
+    return Func(ArrayRef<const ArgT *>());
+  }
+
+#define LLVM_DEFINE_OVERLOAD(N) \
+  ResultT operator()(LLVM_COMMA_JOIN ## N(const ArgT &A)) const { \
+    const ArgT *const Args[] = { LLVM_COMMA_JOIN ## N(&A) }; \
+    return Func(Args); \
+  }
+  LLVM_DEFINE_OVERLOAD(1)
+  LLVM_DEFINE_OVERLOAD(2)
+  LLVM_DEFINE_OVERLOAD(3)
+  LLVM_DEFINE_OVERLOAD(4)
+  LLVM_DEFINE_OVERLOAD(5)
+  LLVM_DEFINE_OVERLOAD(6)
+  LLVM_DEFINE_OVERLOAD(7)
+  LLVM_DEFINE_OVERLOAD(8)
+  LLVM_DEFINE_OVERLOAD(9)
+  LLVM_DEFINE_OVERLOAD(10)
+  LLVM_DEFINE_OVERLOAD(11)
+  LLVM_DEFINE_OVERLOAD(12)
+  LLVM_DEFINE_OVERLOAD(13)
+  LLVM_DEFINE_OVERLOAD(14)
+  LLVM_DEFINE_OVERLOAD(15)
+  LLVM_DEFINE_OVERLOAD(16)
+  LLVM_DEFINE_OVERLOAD(17)
+  LLVM_DEFINE_OVERLOAD(18)
+  LLVM_DEFINE_OVERLOAD(19)
+  LLVM_DEFINE_OVERLOAD(20)
+  LLVM_DEFINE_OVERLOAD(21)
+  LLVM_DEFINE_OVERLOAD(22)
+  LLVM_DEFINE_OVERLOAD(23)
+  LLVM_DEFINE_OVERLOAD(24)
+  LLVM_DEFINE_OVERLOAD(25)
+  LLVM_DEFINE_OVERLOAD(26)
+  LLVM_DEFINE_OVERLOAD(27)
+  LLVM_DEFINE_OVERLOAD(28)
+  LLVM_DEFINE_OVERLOAD(29)
+  LLVM_DEFINE_OVERLOAD(30)
+  LLVM_DEFINE_OVERLOAD(31)
+  LLVM_DEFINE_OVERLOAD(32)
+#undef LLVM_DEFINE_OVERLOAD
+};
+
+template <typename ResultT, typename Param0T, typename ArgT,
+          ResultT (*Func)(Param0T, ArrayRef<const ArgT *>)>
+class VariadicFunction1 {
+ public:
+  VariadicFunction1() {}
+
+  ResultT operator()(Param0T P0) const {
+    return Func(P0, ArrayRef<const ArgT *>());
+  }
+
+#define LLVM_DEFINE_OVERLOAD(N) \
+  ResultT operator()(Param0T P0, LLVM_COMMA_JOIN ## N(const ArgT &A)) const { \
+    const ArgT *const Args[] = { LLVM_COMMA_JOIN ## N(&A) }; \
+    return Func(P0, Args); \
+  }
+  LLVM_DEFINE_OVERLOAD(1)
+  LLVM_DEFINE_OVERLOAD(2)
+  LLVM_DEFINE_OVERLOAD(3)
+  LLVM_DEFINE_OVERLOAD(4)
+  LLVM_DEFINE_OVERLOAD(5)
+  LLVM_DEFINE_OVERLOAD(6)
+  LLVM_DEFINE_OVERLOAD(7)
+  LLVM_DEFINE_OVERLOAD(8)
+  LLVM_DEFINE_OVERLOAD(9)
+  LLVM_DEFINE_OVERLOAD(10)
+  LLVM_DEFINE_OVERLOAD(11)
+  LLVM_DEFINE_OVERLOAD(12)
+  LLVM_DEFINE_OVERLOAD(13)
+  LLVM_DEFINE_OVERLOAD(14)
+  LLVM_DEFINE_OVERLOAD(15)
+  LLVM_DEFINE_OVERLOAD(16)
+  LLVM_DEFINE_OVERLOAD(17)
+  LLVM_DEFINE_OVERLOAD(18)
+  LLVM_DEFINE_OVERLOAD(19)
+  LLVM_DEFINE_OVERLOAD(20)
+  LLVM_DEFINE_OVERLOAD(21)
+  LLVM_DEFINE_OVERLOAD(22)
+  LLVM_DEFINE_OVERLOAD(23)
+  LLVM_DEFINE_OVERLOAD(24)
+  LLVM_DEFINE_OVERLOAD(25)
+  LLVM_DEFINE_OVERLOAD(26)
+  LLVM_DEFINE_OVERLOAD(27)
+  LLVM_DEFINE_OVERLOAD(28)
+  LLVM_DEFINE_OVERLOAD(29)
+  LLVM_DEFINE_OVERLOAD(30)
+  LLVM_DEFINE_OVERLOAD(31)
+  LLVM_DEFINE_OVERLOAD(32)
+#undef LLVM_DEFINE_OVERLOAD
+};
+
+template <typename ResultT, typename Param0T, typename Param1T, typename ArgT,
+          ResultT (*Func)(Param0T, Param1T, ArrayRef<const ArgT *>)>
+class VariadicFunction2 {
+ public:
+  VariadicFunction2() {}
+
+  ResultT operator()(Param0T P0, Param1T P1) const {
+    return Func(P0, P1, ArrayRef<const ArgT *>());
+  }
+
+#define LLVM_DEFINE_OVERLOAD(N) \
+  ResultT operator()(Param0T P0, Param1T P1, \
+                     LLVM_COMMA_JOIN ## N(const ArgT &A)) const { \
+    const ArgT *const Args[] = { LLVM_COMMA_JOIN ## N(&A) }; \
+    return Func(P0, P1, Args); \
+  }
+  LLVM_DEFINE_OVERLOAD(1)
+  LLVM_DEFINE_OVERLOAD(2)
+  LLVM_DEFINE_OVERLOAD(3)
+  LLVM_DEFINE_OVERLOAD(4)
+  LLVM_DEFINE_OVERLOAD(5)
+  LLVM_DEFINE_OVERLOAD(6)
+  LLVM_DEFINE_OVERLOAD(7)
+  LLVM_DEFINE_OVERLOAD(8)
+  LLVM_DEFINE_OVERLOAD(9)
+  LLVM_DEFINE_OVERLOAD(10)
+  LLVM_DEFINE_OVERLOAD(11)
+  LLVM_DEFINE_OVERLOAD(12)
+  LLVM_DEFINE_OVERLOAD(13)
+  LLVM_DEFINE_OVERLOAD(14)
+  LLVM_DEFINE_OVERLOAD(15)
+  LLVM_DEFINE_OVERLOAD(16)
+  LLVM_DEFINE_OVERLOAD(17)
+  LLVM_DEFINE_OVERLOAD(18)
+  LLVM_DEFINE_OVERLOAD(19)
+  LLVM_DEFINE_OVERLOAD(20)
+  LLVM_DEFINE_OVERLOAD(21)
+  LLVM_DEFINE_OVERLOAD(22)
+  LLVM_DEFINE_OVERLOAD(23)
+  LLVM_DEFINE_OVERLOAD(24)
+  LLVM_DEFINE_OVERLOAD(25)
+  LLVM_DEFINE_OVERLOAD(26)
+  LLVM_DEFINE_OVERLOAD(27)
+  LLVM_DEFINE_OVERLOAD(28)
+  LLVM_DEFINE_OVERLOAD(29)
+  LLVM_DEFINE_OVERLOAD(30)
+  LLVM_DEFINE_OVERLOAD(31)
+  LLVM_DEFINE_OVERLOAD(32)
+#undef LLVM_DEFINE_OVERLOAD
+};
+
+template <typename ResultT, typename Param0T, typename Param1T,
+          typename Param2T, typename ArgT,
+          ResultT (*Func)(Param0T, Param1T, Param2T, ArrayRef<const ArgT *>)>
+class VariadicFunction3 {
+ public:
+  VariadicFunction3() {}
+
+  ResultT operator()(Param0T P0, Param1T P1, Param2T P2) const {
+    return Func(P0, P1, P2, ArrayRef<const ArgT *>());
+  }
+
+#define LLVM_DEFINE_OVERLOAD(N) \
+  ResultT operator()(Param0T P0, Param1T P1, Param2T P2, \
+                     LLVM_COMMA_JOIN ## N(const ArgT &A)) const { \
+    const ArgT *const Args[] = { LLVM_COMMA_JOIN ## N(&A) }; \
+    return Func(P0, P1, P2, Args); \
+  }
+  LLVM_DEFINE_OVERLOAD(1)
+  LLVM_DEFINE_OVERLOAD(2)
+  LLVM_DEFINE_OVERLOAD(3)
+  LLVM_DEFINE_OVERLOAD(4)
+  LLVM_DEFINE_OVERLOAD(5)
+  LLVM_DEFINE_OVERLOAD(6)
+  LLVM_DEFINE_OVERLOAD(7)
+  LLVM_DEFINE_OVERLOAD(8)
+  LLVM_DEFINE_OVERLOAD(9)
+  LLVM_DEFINE_OVERLOAD(10)
+  LLVM_DEFINE_OVERLOAD(11)
+  LLVM_DEFINE_OVERLOAD(12)
+  LLVM_DEFINE_OVERLOAD(13)
+  LLVM_DEFINE_OVERLOAD(14)
+  LLVM_DEFINE_OVERLOAD(15)
+  LLVM_DEFINE_OVERLOAD(16)
+  LLVM_DEFINE_OVERLOAD(17)
+  LLVM_DEFINE_OVERLOAD(18)
+  LLVM_DEFINE_OVERLOAD(19)
+  LLVM_DEFINE_OVERLOAD(20)
+  LLVM_DEFINE_OVERLOAD(21)
+  LLVM_DEFINE_OVERLOAD(22)
+  LLVM_DEFINE_OVERLOAD(23)
+  LLVM_DEFINE_OVERLOAD(24)
+  LLVM_DEFINE_OVERLOAD(25)
+  LLVM_DEFINE_OVERLOAD(26)
+  LLVM_DEFINE_OVERLOAD(27)
+  LLVM_DEFINE_OVERLOAD(28)
+  LLVM_DEFINE_OVERLOAD(29)
+  LLVM_DEFINE_OVERLOAD(30)
+  LLVM_DEFINE_OVERLOAD(31)
+  LLVM_DEFINE_OVERLOAD(32)
+#undef LLVM_DEFINE_OVERLOAD
+};
+
+// Cleanup the macro namespace.
+#undef LLVM_COMMA_JOIN1
+#undef LLVM_COMMA_JOIN2
+#undef LLVM_COMMA_JOIN3
+#undef LLVM_COMMA_JOIN4
+#undef LLVM_COMMA_JOIN5
+#undef LLVM_COMMA_JOIN6
+#undef LLVM_COMMA_JOIN7
+#undef LLVM_COMMA_JOIN8
+#undef LLVM_COMMA_JOIN9
+#undef LLVM_COMMA_JOIN10
+#undef LLVM_COMMA_JOIN11
+#undef LLVM_COMMA_JOIN12
+#undef LLVM_COMMA_JOIN13
+#undef LLVM_COMMA_JOIN14
+#undef LLVM_COMMA_JOIN15
+#undef LLVM_COMMA_JOIN16
+#undef LLVM_COMMA_JOIN17
+#undef LLVM_COMMA_JOIN18
+#undef LLVM_COMMA_JOIN19
+#undef LLVM_COMMA_JOIN20
+#undef LLVM_COMMA_JOIN21
+#undef LLVM_COMMA_JOIN22
+#undef LLVM_COMMA_JOIN23
+#undef LLVM_COMMA_JOIN24
+#undef LLVM_COMMA_JOIN25
+#undef LLVM_COMMA_JOIN26
+#undef LLVM_COMMA_JOIN27
+#undef LLVM_COMMA_JOIN28
+#undef LLVM_COMMA_JOIN29
+#undef LLVM_COMMA_JOIN30
+#undef LLVM_COMMA_JOIN31
+#undef LLVM_COMMA_JOIN32
+
+} // end namespace llvm
+
+#endif  // LLVM_ADT_VARIADIC_FUNCTION_H

diff --git a/unittests/ADT/VariadicFunctionTest.cpp b/unittests/ADT/VariadicFunctionTest.cpp
new file mode 100644 (file)
index 0000000..8e6f5b4
--- /dev/null
+++ b/unittests/ADT/VariadicFunctionTest.cpp
@@ -0,0 +1,110 @@
+//===----------- VariadicFunctionTest.cpp - VariadicFunction unit tests ---===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+
+#include "gtest/gtest.h"
+#include "llvm/ADT/ArrayRef.h"
+#include "llvm/ADT/VariadicFunction.h"
+
+using namespace llvm;
+namespace {
+
+// Defines a variadic function StringCat() to join strings.
+// StringCat()'s arguments and return value have class types.
+std::string StringCatImpl(ArrayRef<const std::string*> Args) {
+  std::string S;
+  for (unsigned i = 0, e = Args.size(); i < e; ++i)
+    S += *Args[i];
+  return S;
+}
+const VariadicFunction<std::string, std::string, StringCatImpl> StringCat;
+
+TEST(VariadicFunctionTest, WorksForClassTypes) {
+  EXPECT_EQ("", StringCat());
+  EXPECT_EQ("a", StringCat("a"));
+  EXPECT_EQ("abc", StringCat("a", "bc"));
+  EXPECT_EQ("0123456789abcdefghijklmnopqrstuv",
+            StringCat("0", "1", "2", "3", "4", "5", "6", "7", "8", "9",
+                      "a", "b", "c", "d", "e", "f", "g", "h", "i", "j",
+                      "k", "l", "m", "n", "o", "p", "q", "r", "s", "t",
+                      "u", "v"));
+}
+
+// Defines a variadic function Sum(), whose arguments and return value
+// have primitive types.
+// The return type of SumImp() is deliberately different from its
+// argument type, as we want to test that this works.
+long SumImpl(ArrayRef<const int*> Args) {
+  long Result = 0;
+  for (unsigned i = 0, e = Args.size(); i < e; ++i)
+    Result += *Args[i];
+  return Result;
+}
+const VariadicFunction<long, int, SumImpl> Sum;
+
+TEST(VariadicFunctionTest, WorksForPrimitiveTypes) {
+  EXPECT_EQ(0, Sum());
+  EXPECT_EQ(1, Sum(1));
+  EXPECT_EQ(12, Sum(10, 2));
+  EXPECT_EQ(1234567, Sum(1000000, 200000, 30000, 4000, 500, 60, 7));
+}
+
+// Appends an array of strings to dest and returns the number of
+// characters appended.
+int StringAppendImpl(std::string* Dest, ArrayRef<const std::string*> Args) {
+  int Chars = 0;
+  for (unsigned i = 0, e = Args.size(); i < e; ++i) {
+    Chars += Args[i]->size();
+    *Dest += *Args[i];
+  }
+  return Chars;
+}
+const VariadicFunction1<int, std::string*, std::string,
+                        StringAppendImpl> StringAppend;
+
+TEST(VariadicFunction1Test, Works) {
+  std::string S0("hi");
+  EXPECT_EQ(0, StringAppend(&S0));
+  EXPECT_EQ("hi", S0);
+
+  std::string S1("bin");
+  EXPECT_EQ(2, StringAppend(&S1, "go"));
+  EXPECT_EQ("bingo", S1);
+
+  std::string S4("Fab4");
+  EXPECT_EQ(4 + 4 + 6 + 5,
+            StringAppend(&S4, "John", "Paul", "George", "Ringo"));
+  EXPECT_EQ("Fab4JohnPaulGeorgeRingo", S4);
+}
+
+// Counts how many optional arguments fall in the given range.
+// Returns the result in *num_in_range.  We make the return type void
+// as we want to test that VariadicFunction* can handle it.
+void CountInRangeImpl(int* NumInRange, int Low, int High,
+                      ArrayRef<const int*> Args) {
+  *NumInRange = 0;
+  for (unsigned i = 0, e = Args.size(); i < e; ++i)
+    if (Low <= *Args[i] && *Args[i] <= High)
+      ++(*NumInRange);
+}
+const VariadicFunction3<void, int*, int, int, int,
+                        CountInRangeImpl> CountInRange;
+
+TEST(VariadicFunction3Test, Works) {
+  int N = -1;
+  CountInRange(&N, -100, 100);
+  EXPECT_EQ(0, N);
+
+  CountInRange(&N, -100, 100, 42);
+  EXPECT_EQ(1, N);
+
+  CountInRange(&N, -100, 100, 1, 999, -200, 42);
+  EXPECT_EQ(2, N);
+}
+
+}  // namespace

diff --git a/unittests/CMakeLists.txt b/unittests/CMakeLists.txt
index 15423dce460a9f7a8e2cea2bd5c8254718958716..0fabf710661e8e52414ef446c5b362b169990d0f 100644 (file)
--- a/unittests/CMakeLists.txt
+++ b/unittests/CMakeLists.txt
@@ -73,6 +73,7 @@ add_llvm_unittest(ADT
   ADT/StringRefTest.cpp
   ADT/TripleTest.cpp
   ADT/TwineTest.cpp
+  ADT/VariadicFunctionTest.cpp
  )
 
 add_llvm_unittest(Analysis