Implement integer precision.

format.cc

@@ -350,45 +350,6 @@ typename fmt::BasicWriter<Char>::CharPtr
   return content;
 }
 
-template <typename Char>
-typename fmt::BasicWriter<Char>::CharPtr
-  fmt::BasicWriter<Char>::PrepareFilledBuffer(unsigned num_digits,
-    const AlignSpec &spec, const char *prefix, unsigned prefix_size) {
-  unsigned size = prefix_size + num_digits;
-  unsigned width = spec.width();
-  if (width <= size) {
-    CharPtr p = GrowBuffer(size);
-    std::copy(prefix, prefix + prefix_size, p);
-    return p + size - 1;
-  }
-  CharPtr p = GrowBuffer(width);
-  CharPtr end = p + width;
-  Alignment align = spec.align();
-  // TODO: error if fill is not convertible to Char
-  Char fill = static_cast<Char>(spec.fill());
-  if (align == ALIGN_LEFT) {
-    std::copy(prefix, prefix + prefix_size, p);
-    p += size;
-    std::fill(p, end, fill);
-  } else if (align == ALIGN_CENTER) {
-    p = FillPadding(p, width, size, fill);
-    std::copy(prefix, prefix + prefix_size, p);
-    p += size;
-  } else {
-    if (align == ALIGN_NUMERIC) {
-      if (prefix_size != 0) {
-        p = std::copy(prefix, prefix + prefix_size, p);
-        size -= prefix_size;
-      }
-    } else {
-      std::copy(prefix, prefix + prefix_size, end - size);
-    }
-    std::fill(p, end - size, fill);
-    p = end;
-  }
-  return p - 1;
-}
-
 template <typename Char>
 template <typename T>
 void fmt::BasicWriter<Char>::FormatDouble(
@@ -637,7 +598,7 @@ unsigned fmt::BasicWriter<Char>::PrintfParser::ParseHeader(
   Char c = *s;
   if (c >= '0' && c <= '9') {
     // Parse an argument index (if followed by '$') or a width possibly
-    // preceded with a '0' flag.
+    // preceded with '0' flag(s).
     unsigned value = internal::ParseNonnegativeInt(s, error);
     if (*s == '$') {  // value is an argument index
       ++s;
@@ -668,7 +629,7 @@ unsigned fmt::BasicWriter<Char>::PrintfParser::ParseHeader(
   return arg_index;
 }
 
-// FIXME: this doesnt' depend on template argument
+// TODO: move to a base class that doesn't depend on template argument
 template <typename Char>
 const typename fmt::BasicWriter<Char>::ArgInfo
   &fmt::BasicWriter<Char>::PrintfParser::HandleArgIndex(
@@ -738,16 +699,11 @@ void fmt::BasicWriter<Char>::PrintfParser::Format(
     }
 
     // Parse precision.
-    int precision = -1;
-    /*if (*s == '.') {
+    if (*s == '.') {
       ++s;
-      precision = 0;
-      if ('0' <= *s && *s <= '9') {
-        unsigned value = ParseNonnegativeInt(s);
-        if (value > INT_MAX)
-          ReportError(s, "number is too big in format");
-        precision = value;
-      } else if (*s == '{') {
+      if ('0' <= *s && *s <= '9')
+        spec.precision_ = internal::ParseNonnegativeInt(s, error);
+      /*else if (*s == '*') {
         ++s;
         ++num_open_braces_;
         const ArgInfo &precision_arg = ParseArgIndex(s);
@@ -792,8 +748,8 @@ void fmt::BasicWriter<Char>::PrintfParser::Format(
       if (arg.type != DOUBLE && arg.type != LONG_DOUBLE) {
         ReportError(s,
             "precision specifier requires floating-point argument");
-      }
-    }*/
+      }*/
+    }
 
     // Parse type.
     if (!*s)
@@ -825,10 +781,10 @@ void fmt::BasicWriter<Char>::PrintfParser::Format(
       writer.FormatInt(arg.ulong_long_value, spec);
       break;
     case DOUBLE:
-      writer.FormatDouble(arg.double_value, spec, precision);
+      writer.FormatDouble(arg.double_value, spec, spec.precision_);
       break;
     case LONG_DOUBLE:
-      writer.FormatDouble(arg.long_double_value, spec, precision);
+      writer.FormatDouble(arg.long_double_value, spec, spec.precision_);
       break;
     case CHAR: {
       if (spec.type_ && spec.type_ != 'c')
@@ -1175,10 +1131,6 @@ template fmt::BasicWriter<char>::CharPtr
   fmt::BasicWriter<char>::FillPadding(CharPtr buffer,
     unsigned total_size, std::size_t content_size, wchar_t fill);
 
-template fmt::BasicWriter<char>::CharPtr
-  fmt::BasicWriter<char>::PrepareFilledBuffer(unsigned num_digits,
-    const AlignSpec &spec, const char *prefix, unsigned prefix_size);
-
 template void fmt::BasicWriter<char>::FormatParser::Format(
   BasicWriter<char> &writer, BasicStringRef<char> format,
   std::size_t num_args, const ArgInfo *args);
@@ -1193,10 +1145,6 @@ template fmt::BasicWriter<wchar_t>::CharPtr
   fmt::BasicWriter<wchar_t>::FillPadding(CharPtr buffer,
     unsigned total_size, std::size_t content_size, wchar_t fill);
 
-template fmt::BasicWriter<wchar_t>::CharPtr
-  fmt::BasicWriter<wchar_t>::PrepareFilledBuffer(unsigned num_digits,
-    const AlignSpec &spec, const char *prefix, unsigned prefix_size);
-
 template void fmt::BasicWriter<wchar_t>::FormatParser::Format(
     BasicWriter<wchar_t> &writer, BasicStringRef<wchar_t> format,
     std::size_t num_args, const ArgInfo *args);

format.h

@@ -586,6 +586,7 @@ template <char TYPE>
 struct TypeSpec : EmptySpec {
   Alignment align() const { return ALIGN_DEFAULT; }
   unsigned width() const { return 0; }
+  int precision() const { return -1; }
 
   bool sign_flag() const { return false; }
   bool plus_flag() const { return false; }
@@ -616,6 +617,8 @@ struct AlignSpec : WidthSpec {
   : WidthSpec(width, fill), align_(align) {}
 
   Alignment align() const { return align_; }
+
+  int precision() const { return -1; }
 };
 
 // An alignment and type specifier.
@@ -633,15 +636,19 @@ struct AlignTypeSpec : AlignSpec {
 // A full format specifier.
 struct FormatSpec : AlignSpec {
   unsigned flags_;
+  int precision_;
   char type_;
 
-  FormatSpec(unsigned width = 0, char type = 0, wchar_t fill = ' ')
-  : AlignSpec(width, fill), flags_(0), type_(type) {}
+  FormatSpec(
+    unsigned width = 0, char type = 0, wchar_t fill = ' ')
+  : AlignSpec(width, fill), flags_(0), precision_(-1), type_(type) {}
 
   bool sign_flag() const { return (flags_ & SIGN_FLAG) != 0; }
   bool plus_flag() const { return (flags_ & PLUS_FLAG) != 0; }
   bool hash_flag() const { return (flags_ & HASH_FLAG) != 0; }
 
+  int precision() const { return precision_; }
+
   char type() const { return type_; }
 };
 
@@ -860,14 +867,16 @@ class BasicWriter {
     return p + size - 1;
   }
 
+  template <typename Spec>
   CharPtr PrepareFilledBuffer(unsigned num_digits,
-    const AlignSpec &spec, const char *prefix, unsigned prefix_size);
+    const Spec &spec, const char *prefix, unsigned prefix_size);
 
   // Formats an integer.
   template <typename T, typename Spec>
   void FormatInt(T value, const Spec &spec);
 
   // Formats a floating-point number (double or long double).
+  // TODO: use precision from spec
   template <typename T>
   void FormatDouble(T value, const FormatSpec &spec, int precision);
 
@@ -1294,6 +1303,52 @@ typename BasicWriter<Char>::CharPtr BasicWriter<Char>::FormatString(
   return out;
 }
 
+template <typename Char>
+template <typename Spec>
+typename fmt::BasicWriter<Char>::CharPtr
+fmt::BasicWriter<Char>::PrepareFilledBuffer(unsigned num_digits,
+  const Spec &spec, const char *prefix, unsigned prefix_size) {
+  if (spec.precision() >= 0) {
+    // TODO: fill up to width if necessary
+    return PrepareFilledBuffer(num_digits,
+      AlignSpec(spec.precision() + prefix_size, '0', ALIGN_NUMERIC),
+      prefix, prefix_size);
+  }
+  unsigned size = prefix_size + num_digits;
+  unsigned width = spec.width();
+  if (width <= size) {
+    CharPtr p = GrowBuffer(size);
+    std::copy(prefix, prefix + prefix_size, p);
+    return p + size - 1;
+  }
+  CharPtr p = GrowBuffer(width);
+  CharPtr end = p + width;
+  Alignment align = spec.align();
+  // TODO: error if fill is not convertible to Char
+  Char fill = static_cast<Char>(spec.fill());
+  if (align == ALIGN_LEFT) {
+    std::copy(prefix, prefix + prefix_size, p);
+    p += size;
+    std::fill(p, end, fill);
+  } else if (align == ALIGN_CENTER) {
+    p = FillPadding(p, width, size, fill);
+    std::copy(prefix, prefix + prefix_size, p);
+    p += size;
+  } else {
+    if (align == ALIGN_NUMERIC) {
+      if (prefix_size != 0) {
+        p = std::copy(prefix, prefix + prefix_size, p);
+        size -= prefix_size;
+      }
+    } else {
+      std::copy(prefix, prefix + prefix_size, end - size);
+    }
+    std::fill(p, end - size, fill);
+    p = end;
+  }
+  return p - 1;
+}
+
 template <typename Char>
 template <typename T, typename Spec>
 void BasicWriter<Char>::FormatInt(T value, const Spec &spec) {

test/printf-test.cc

@@ -133,27 +133,6 @@ TEST(PrintfTest, DefaultAlignRight) {
   EXPECT_PRINTF("  abc", "%5s", "abc");
 }
 
-TEST(PrintfTest, Width) {
-  EXPECT_PRINTF("  abc", "%5s", "abc");
-
-  // Width cannot be specified twice.
-  EXPECT_THROW_MSG(fmt::sprintf("%5-5d", 42), FormatError,
-      "unknown format code '-' for integer");
-
-  EXPECT_THROW_MSG(fmt::sprintf(str(Format("%{}d", BIG_NUM)), 42),
-      FormatError, "number is too big in format");
-  EXPECT_THROW_MSG(fmt::sprintf(str(Format("%1${}d", BIG_NUM)), 42),
-      FormatError, "number is too big in format");
-}
-
-TEST(PrintfTest, DynamicWidth) {
-  EXPECT_EQ("   42", str(fmt::sprintf("%*d", 5, 42)));
-  EXPECT_THROW_MSG(fmt::sprintf("%*d", 5.0, 42), FormatError,
-      "width is not integer");
-  EXPECT_THROW_MSG(fmt::sprintf("%*d"), FormatError,
-      "argument index is out of range in format");
-}
-
 TEST(PrintfTest, ZeroFlag) {
   EXPECT_PRINTF("00042", "%05d", 42);
   EXPECT_PRINTF("-0042", "%05d", -42);
@@ -227,6 +206,31 @@ TEST(PrintfTest, HashFlag) {
   EXPECT_PRINTF("x", "%#c", 'x');
 }
 
-// TODO: test '*' width, precision, length and type specifier
+TEST(PrintfTest, Width) {
+  EXPECT_PRINTF("  abc", "%5s", "abc");
+
+  // Width cannot be specified twice.
+  EXPECT_THROW_MSG(fmt::sprintf("%5-5d", 42), FormatError,
+      "unknown format code '-' for integer");
+
+  EXPECT_THROW_MSG(fmt::sprintf(str(Format("%{}d", BIG_NUM)), 42),
+      FormatError, "number is too big in format");
+  EXPECT_THROW_MSG(fmt::sprintf(str(Format("%1${}d", BIG_NUM)), 42),
+      FormatError, "number is too big in format");
+}
+
+TEST(PrintfTest, DynamicWidth) {
+  EXPECT_EQ("   42", str(fmt::sprintf("%*d", 5, 42)));
+  EXPECT_THROW_MSG(fmt::sprintf("%*d", 5.0, 42), FormatError,
+      "width is not integer");
+  EXPECT_THROW_MSG(fmt::sprintf("%*d"), FormatError,
+      "argument index is out of range in format");
+}
+
+TEST(PrintfTest, Precision) {
+  EXPECT_PRINTF("00042", "%.5d", 42);
+}
+
+// TODO: test precision, length and type specifier
 
 #endif