[Support] Introduce llvm::formatv() function.

This introduces a new type-safe general purpose formatting
library.  It provides compile-time type safety, does not require
a format specifier (since the type is deduced), and provides
mechanisms for extending the format capability to user defined
types, and overriding the formatting behavior for existing types.

This patch additionally adds documentation for the API to the
LLVM programmer's manual.

Mailing List Thread:
http://lists.llvm.org/pipermail/llvm-dev/2016-October/105836.html

Differential Revision: https://reviews.llvm.org/D25587

llvm-svn: 286682

1 files changed, 44 insertions, 23 deletions

diff --git a/llvm/lib/Support/NativeFormatting.cpp b/llvm/lib/Support/NativeFormatting.cpp
index dbfe658e87c..bb868914109 100644
--- a/llvm/lib/Support/NativeFormatting.cpp
+++ b/llvm/lib/Support/NativeFormatting.cpp
@@ -47,8 +47,8 @@ static void writeWithCommas(raw_ostream &S, ArrayRef<char> Buffer) {
 }
 
 template <typename T>
-static void write_unsigned_impl(raw_ostream &S, T N, IntegerStyle Style,
-                                bool IsNegative) {
+static void write_unsigned_impl(raw_ostream &S, T N, size_t MinDigits,
+                                IntegerStyle Style, bool IsNegative) {
   static_assert(std::is_unsigned<T>::value, "Value is not unsigned!");
 
   char NumberBuffer[128];
@@ -59,6 +59,12 @@ static void write_unsigned_impl(raw_ostream &S, T N, IntegerStyle Style,
 
   if (IsNegative)
     S << '-';
+
+  if (Len < MinDigits && Style != IntegerStyle::Number) {
+    for (size_t I = Len; I < MinDigits; ++I)
+      S << '0';
+  }
+
   if (Style == IntegerStyle::Number) {
     writeWithCommas(S, ArrayRef<char>(std::end(NumberBuffer) - Len, Len));
   } else {
@@ -67,53 +73,60 @@ static void write_unsigned_impl(raw_ostream &S, T N, IntegerStyle Style,
 }
 
 template <typename T>
-static void write_unsigned(raw_ostream &S, T N, IntegerStyle Style,
-                           bool IsNegative = false) {
+static void write_unsigned(raw_ostream &S, T N, size_t MinDigits,
+                           IntegerStyle Style, bool IsNegative = false) {
   // Output using 32-bit div/mod if possible.
   if (N == static_cast<uint32_t>(N))
-    write_unsigned_impl(S, static_cast<uint32_t>(N), Style, IsNegative);
+    write_unsigned_impl(S, static_cast<uint32_t>(N), MinDigits, Style,
+                        IsNegative);
   else
-    write_unsigned_impl(S, N, Style, IsNegative);
+    write_unsigned_impl(S, N, MinDigits, Style, IsNegative);
 }
 
 template <typename T>
-static void write_signed(raw_ostream &S, T N, IntegerStyle Style) {
+static void write_signed(raw_ostream &S, T N, size_t MinDigits,
+                         IntegerStyle Style) {
   static_assert(std::is_signed<T>::value, "Value is not signed!");
 
   using UnsignedT = typename std::make_unsigned<T>::type;
 
   if (N >= 0) {
-    write_unsigned(S, static_cast<UnsignedT>(N), Style);
+    write_unsigned(S, static_cast<UnsignedT>(N), MinDigits, Style);
     return;
   }
 
   UnsignedT UN = -(UnsignedT)N;
-  write_unsigned(S, UN, Style, true);
+  write_unsigned(S, UN, MinDigits, Style, true);
 }
 
-void llvm::write_integer(raw_ostream &S, unsigned int N, IntegerStyle Style) {
-  write_unsigned(S, N, Style);
+void llvm::write_integer(raw_ostream &S, unsigned int N, size_t MinDigits,
+                         IntegerStyle Style) {
+  write_unsigned(S, N, MinDigits, Style);
 }
 
-void llvm::write_integer(raw_ostream &S, int N, IntegerStyle Style) {
-  write_signed(S, N, Style);
+void llvm::write_integer(raw_ostream &S, int N, size_t MinDigits,
+                         IntegerStyle Style) {
+  write_signed(S, N, MinDigits, Style);
 }
 
-void llvm::write_integer(raw_ostream &S, unsigned long N, IntegerStyle Style) {
-  write_unsigned(S, N, Style);
+void llvm::write_integer(raw_ostream &S, unsigned long N, size_t MinDigits,
+                         IntegerStyle Style) {
+  write_unsigned(S, N, MinDigits, Style);
 }
 
-void llvm::write_integer(raw_ostream &S, long N, IntegerStyle Style) {
-  write_signed(S, N, Style);
+void llvm::write_integer(raw_ostream &S, long N, size_t MinDigits,
+                         IntegerStyle Style) {
+  write_signed(S, N, MinDigits, Style);
 }
 
-void llvm::write_integer(raw_ostream &S, unsigned long long N,
+void llvm::write_integer(raw_ostream &S, unsigned long long N, size_t MinDigits,
                          IntegerStyle Style) {
-  write_unsigned(S, N, Style);
+  write_unsigned(S, N, MinDigits, Style);
 }
 
-void llvm::write_integer(raw_ostream &S, long long N, IntegerStyle Style) {
-  write_signed(S, N, Style);
+void llvm::write_integer(raw_ostream &S, long long N, size_t MinDigits,
+                         IntegerStyle Style) {
+  write_signed(S, N, MinDigits, Style);
 }
 
 void llvm::write_hex(raw_ostream &S, uint64_t N, HexPrintStyle Style,
@@ -178,7 +191,9 @@ void llvm::write_double(raw_ostream &S, double N, FloatStyle Style,
 #if defined(__MINGW32__)
     // FIXME: It should be generic to C++11.
     if (N == 0.0 && std::signbit(N)) {
-      const char *NegativeZero = "-0.000000e+00";
+      char NegativeZero[] = "-0.000000e+00";
+      if (Style == FloatStyle::ExponentUpper)
+        NegativeZero[strlen(NegativeZero) - 4] = 'E';
       S << NegativeZero;
       return;
     }
@@ -187,7 +202,9 @@ void llvm::write_double(raw_ostream &S, double N, FloatStyle Style,
 
     // negative zero
     if (fpcl == _FPCLASS_NZ) {
-      const char *NegativeZero = "-0.000000e+00";
+      char NegativeZero[] = "-0.000000e+00";
+      if (Style == FloatStyle::ExponentUpper)
+        NegativeZero[strlen(NegativeZero) - 4] = 'E';
       S << NegativeZero;
       return;
     }
@@ -231,6 +248,10 @@ void llvm::write_double(raw_ostream &S, double N, FloatStyle Style,
     S << '%';
 }
 
+bool llvm::isPrefixedHexStyle(HexPrintStyle S) {
+  return (S == HexPrintStyle::PrefixLower || S == HexPrintStyle::PrefixUpper);
+}
+
 size_t llvm::getDefaultPrecision(FloatStyle Style) {
   switch (Style) {
   case FloatStyle::Exponent: