Merge branch 'pr/53'

Author: c42f

README.md

@@ -202,9 +202,11 @@ means that a `bool` variable printed with "%s" will come out as `true` or
 Not all features of printf can be simulated simply using standard iostreams.
 Here's a list of known incompatibilities:
 
-* The C99 `"%a"` and `"%A"` hexadecimal floating point conversions are not
-  supported since the iostreams don't have the necessary flags.  Using either
-  of these flags will result in a call to `TINYFORMAT_ERROR`.
+* The `"%a"` and `"%A"` hexadecimal floating point conversions ignore precision
+  as stream output of hexfloat (introduced in C++11) ignores precision, always
+  outputting the minimum number of digits required for exact representation.
+  MSVC incorrectly honors stream precision, so we force precision to 13 in this
+  case to guarentee lossless roundtrip conversion.
 * The precision for integer conversions cannot be supported by the iostreams
   state independently of the field width.  (Note: **this is only a
   problem for certain obscure integer conversions**; float conversions like

appveyor.yml

@@ -48,5 +48,5 @@ build_script:
 
 test_script:
   # cmake testall target has problems finding the correct configuration, so use ctest directly.
-  - ctest -C %CONFIGURATION%
+  - ctest -VV -C %CONFIGURATION%
 

tinyformat.h

@@ -496,7 +496,7 @@ namespace detail {
 
 // Type-opaque holder for an argument to format(), with associated actions on
 // the type held as explicit function pointers.  This allows FormatArg's for
-// each argument to be allocated as a homogenous array inside FormatList
+// each argument to be allocated as a homogeneous array inside FormatList
 // whereas a naive implementation based on inheritance does not.
 class FormatArg
 {
@@ -838,6 +838,18 @@ inline const char* streamStateFromFormat(std::ostream& out, bool& positionalMode
         case 'f':
             out.setf(std::ios::fixed, std::ios::floatfield);
             break;
+        case 'A':
+            out.setf(std::ios::uppercase);
+            // Falls through
+        case 'a':
+#           ifdef _MSC_VER
+            // Workaround https://developercommunity.visualstudio.com/content/problem/520472/hexfloat-stream-output-does-not-ignore-precision-a.html
+            // by always setting maximum precision on MSVC to avoid precision
+            // loss for doubles.
+            out.precision(13);
+#           endif
+            out.setf(std::ios::fixed | std::ios::scientific, std::ios::floatfield);
+            break;
         case 'G':
             out.setf(std::ios::uppercase);
             // Falls through
@@ -846,17 +858,13 @@ inline const char* streamStateFromFormat(std::ostream& out, bool& positionalMode
             // As in boost::format, let stream decide float format.
             out.flags(out.flags() & ~std::ios::floatfield);
             break;
-        case 'a': case 'A':
-            TINYFORMAT_ERROR("tinyformat: the %a and %A conversion specs "
-                             "are not supported");
-            break;
         case 'c':
             // Handled as special case inside formatValue()
             break;
         case 's':
             if(precisionSet)
                 ntrunc = static_cast<int>(out.precision());
-            // Make %s print booleans as "true" and "false"
+            // Make %s print Booleans as "true" and "false"
             out.setf(std::ios::boolalpha);
             break;
         case 'n':

tinyformat_test.cpp

@@ -122,6 +122,13 @@ int unitTests()
     CHECK_EQUAL(tfm::format("%E", -1.23456E10), "-1.234560E+10");
     CHECK_EQUAL(tfm::format("%f", -9.8765), "-9.876500");
     CHECK_EQUAL(tfm::format("%F", 9.8765), "9.876500");
+#   ifndef _MSC_VER
+    CHECK_EQUAL(tfm::format("%a", -1.671111047267913818359375), "-0x1.abcdefp+0");
+    CHECK_EQUAL(tfm::format("%A",  1.671111047267913818359375),  "0X1.ABCDEFP+0");
+#   else
+    CHECK_EQUAL(tfm::format("%a", -1.671111047267913818359375), "-0x1.abcdef0000000p+0");
+    CHECK_EQUAL(tfm::format("%A",  1.671111047267913818359375),  "0X1.ABCDEF0000000P+0");
+#   endif
     CHECK_EQUAL(tfm::format("%g", 10), "10");
     CHECK_EQUAL(tfm::format("%G", 100), "100");
     CHECK_EQUAL(tfm::format("%c", 65), "A");
@@ -163,6 +170,16 @@ int unitTests()
     CHECK_EQUAL(tfm::format("%.4d", 10), "0010");
     CHECK_EQUAL(tfm::format("%10.4f", 1234.1234567890), " 1234.1235");
     CHECK_EQUAL(tfm::format("%.f", 10.1), "10");
+    // Per C++ spec, iostreams ignore the precision for "%a" to avoid precision
+    // loss. This is a printf incompatibility.
+#   ifndef _MSC_VER
+    CHECK_EQUAL(tfm::format("%.1a", 1.13671875), "0x1.23p+0");
+    CHECK_EQUAL(tfm::format("%14a", 1.671111047267913818359375), " 0x1.abcdefp+0");
+#   else
+    // MSVC workaround
+    CHECK_EQUAL(tfm::format("%.1a", 1.13671875), "0x1.2300000000000p+0");
+    CHECK_EQUAL(tfm::format("%21a", 1.671111047267913818359375), " 0x1.abcdef0000000p+0");
+#   endif
     CHECK_EQUAL(tfm::format("%.2s", "asdf"), "as"); // strings truncate to precision
     CHECK_EQUAL(tfm::format("%.2s", std::string("asdf")), "as");
     // Test variable precision & width
@@ -245,8 +262,6 @@ int unitTests()
 
     // Unhandled C99 format spec
     EXPECT_ERROR( tfm::format("%n", 10) )
-    EXPECT_ERROR( tfm::format("%a", 10) )
-    EXPECT_ERROR( tfm::format("%A", 10) )
 
 #ifdef TEST_WCHAR_T_COMPILE
     // Test wchar_t handling - should fail to compile!