[Support] Add type-safe alternative to llvm::format()

llvm::format() is somewhat unsafe. The compiler does not check that integer
parameter size matches the %x or %d size and it does not complain when a 
StringRef is passed for a %s.  And correctly using a StringRef with format() is  
ugly because you have to convert it to a std::string then call c_str().
 
The cases where llvm::format() is useful is controlling how numbers and
strings are printed, especially when you want fixed width output.  This
patch adds some new formatting functions to raw_streams to format numbers
and StringRefs in a type safe manner. Some examples:

   OS << format_hex(255, 6)        => "0x00ff"
   OS << format_hex(255, 4)        => "0xff"
   OS << format_decimal(0, 5)      => "    0"
   OS << format_decimal(255, 5)    => "  255"
   OS << right_justify(Str, 5)     => "  foo"
   OS << left_justify(Str, 5)      => "foo  "



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@218463 91177308-0d34-0410-b5e6-96231b3b80d8

lib/Support/raw_ostream.cpp

@@ -20,6 +20,7 @@
 #include "llvm/Support/ErrorHandling.h"
 #include "llvm/Support/FileSystem.h"
 #include "llvm/Support/Format.h"
+#include "llvm/Support/MathExtras.h"
 #include "llvm/Support/Process.h"
 #include "llvm/Support/Program.h"
 #include <cctype>
@@ -394,6 +395,62 @@ raw_ostream &raw_ostream::operator<<(const format_object_base &Fmt) {
   }
 }
 
+raw_ostream &raw_ostream::operator<<(const FormattedString &FS) {
+  unsigned Len = FS.Str.size(); 
+  int PadAmount = FS.Width - Len;
+  if (FS.RightJustify && (PadAmount > 0))
+    this->indent(PadAmount);
+  this->operator<<(FS.Str);
+  if (!FS.RightJustify && (PadAmount > 0))
+    this->indent(PadAmount);
+  return *this;
+}
+
+raw_ostream &raw_ostream::operator<<(const FormattedNumber &FN) {
+  if (FN.Hex) {
+    unsigned Nibbles = (64 - countLeadingZeros(FN.HexValue)+3)/4;
+    unsigned Width = (FN.Width > Nibbles+2) ? FN.Width : Nibbles+2;
+        
+    char NumberBuffer[20] = "0x0000000000000000";
+    char *EndPtr = NumberBuffer+Width;
+    char *CurPtr = EndPtr;
+    const char A = FN.Upper ? 'A' : 'a';
+    unsigned long long N = FN.HexValue;
+    while (N) {
+      uintptr_t x = N % 16;
+      *--CurPtr = (x < 10 ? '0' + x : A + x - 10);
+      N /= 16;
+    }
+
+    return write(NumberBuffer, Width);
+  } else {
+    // Zero is a special case.
+    if (FN.DecValue == 0) {
+      this->indent(FN.Width-1);
+      return *this << '0';
+    }
+    char NumberBuffer[32];
+    char *EndPtr = NumberBuffer+sizeof(NumberBuffer);
+    char *CurPtr = EndPtr;
+    bool Neg = (FN.DecValue < 0);
+    uint64_t N = Neg ? -FN.DecValue : FN.DecValue;
+    while (N) {
+      *--CurPtr = '0' + char(N % 10);
+      N /= 10;
+    }
+    int Len = EndPtr - CurPtr;
+    int Pad = FN.Width - Len;
+    if (Neg) 
+      --Pad;
+    if (Pad > 0)
+      this->indent(Pad);
+    if (Neg)
+      *this << '-';
+    return write(CurPtr, Len);
+  }
+}
+
+
 /// indent - Insert 'NumSpaces' spaces.
 raw_ostream &raw_ostream::indent(unsigned NumSpaces) {
   static const char Spaces[] = "                                "