Add fast_float for float parsing.

2x faster than both std::from_chars and strtod on Windows.

macOS will get to benefit from a modern from_chars impl too.

common/CMakeLists.txt

@@ -269,6 +269,7 @@ target_link_libraries( kicommon
     kiplatform
     nlohmann_json
     nlohmann_json_schema_validator
+    FastFloat::fast_float
     fmt::fmt
     CURL::libcurl
     picosha2

common/dsnlexer.cpp

@@ -22,7 +22,7 @@
  * 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA
  */
 
-#include <charconv>
+#include <fast_float/fast_float.h>
 #include <cstdarg>
 #include <cstdio>
 #include <cstdlib>         // bsearch()
@@ -861,43 +861,13 @@ wxArrayString* DSNLEXER::ReadCommentLines()
 
 double DSNLEXER::parseDouble()
 {
-// We try here to be locale independent to avoid the need to switch to a "C" locale
+    // Use fast_float::from_chars which is designed to be locale independent and significantly
-#if ( defined( __GNUC__ ) && __GNUC__ < 11 ) || ( defined( __clang__ ) && __clang_major__ < 13 )
+    // faster than strtod and std::from_chars
-    // GCC older than 11 "supports" C++17 without supporting the C++17 std::from_chars for doubles
-    // clang is similar
-
-    // Use wxString::ToCDouble() which is designed to be locale independent
-    wxString tmp = CurStr();
-    double fval;
-    bool success = tmp.ToCDouble( &fval );
-
-    if( !success )
-    {
-        wxString error;
-        error.Printf( _( "Invalid floating point number in\nfile: '%s'\nline: %d\noffset: %d" ),
-                      CurSource(), CurLineNumber(), CurOffset() );
-
-        THROW_IO_ERROR( error );
-    }
-
-    return fval;
-#else
-    // Use std::from_chars which is designed to be locale independent and performance oriented
-    // for data interchange
-
     const std::string& str = CurStr();
 
-    // Offset any leading whitespace, this is one thing from_chars does not handle
-    size_t woff = 0;
-
-    while( std::isspace( str[woff] ) && woff < str.length() )
-    {
-        woff++;
-    }
-
     double                 dval{};
-    std::from_chars_result res =
+    fast_float::from_chars_result res = fast_float::from_chars( str.data(), str.data() + str.size(), dval,
-            std::from_chars( str.data() + woff, str.data() + str.size(), dval );
+                                                                fast_float::chars_format::skip_white_space );
 
     if( res.ec != std::errc() )
     {
@@ -906,5 +876,4 @@ double DSNLEXER::parseDouble()
     }
 
     return dval;
-#endif
 }

eeschema/sim/sim_value.cpp

@@ -22,7 +22,7 @@
  * 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA
  */
 
-#include <charconv>
+#include <fast_float/fast_float.h>
 #include <sim/sim_value.h>
 #include <wx/translation.h>
 #include <ki_exception.h>
@@ -382,22 +382,20 @@ std::string SIM_VALUE::ConvertNotation( const std::string& aString, NOTATION aFr
         int exponent = parseResult.exponent ? *parseResult.exponent : 0;
         exponent += parseResult.unitPrefixExponent ? *parseResult.unitPrefixExponent : 0;
 
-        try
+        int         expReduction = 0;
-        {
+        std::string prefix = SIM_VALUE_PARSER::ExponentToUnitPrefix( exponent, expReduction,
-            int         expReduction = 0;
+                                                                        aToNotation );
-            std::string prefix = SIM_VALUE_PARSER::ExponentToUnitPrefix( exponent, expReduction,
+        double significand{};
-                                                                         aToNotation );
-            double significand{};
-            wxString( parseResult.significand ).ToCDouble( &significand );
 
-            exponent -= expReduction;
+        fast_float::from_chars(
-            return fmt::format( "{:g}{}", significand * std::pow( 10, exponent ),
+                parseResult.significand.data(),
-                                prefix );
+                parseResult.significand.data() + parseResult.significand.size(),
-        }
+                significand,
-        catch( const std::invalid_argument& )
+                fast_float::chars_format::skip_white_space | fast_float::chars_format::allow_leading_plus );
-        {
+
-            // best efforts
+        exponent -= expReduction;
-        }
+        return fmt::format( "{:g}{}", significand * std::pow( 10, exponent ),
+                            prefix );
     }
 
     return aString;
@@ -446,19 +444,17 @@ double SIM_VALUE::ToDouble( const std::string& aString, double aDefault )
 
     if( parseResult.isOk && !parseResult.isEmpty && !parseResult.significand.empty() )
     {
-        try
+        int       exponent = parseResult.exponent ? *parseResult.exponent : 0;
-        {
-            LOCALE_IO toggle;
-            int       exponent = parseResult.exponent ? *parseResult.exponent : 0;
 
-            exponent += parseResult.unitPrefixExponent ? *parseResult.unitPrefixExponent : 0;
+        exponent += parseResult.unitPrefixExponent ? *parseResult.unitPrefixExponent : 0;
+        double significand{};
 
-            return std::stod( parseResult.significand ) * std::pow( 10, exponent );
+        fast_float::from_chars( parseResult.significand.data(),
-        }
+                                parseResult.significand.data() + parseResult.significand.size(),
-        catch( const std::invalid_argument& )
+                                significand,
-        {
+                                fast_float::chars_format::skip_white_space | fast_float::chars_format::allow_leading_plus );
-            // best efforts
+
-        }
+        return significand * std::pow( 10, exponent );
     }
 
     return aDefault;

thirdparty/CMakeLists.txt

@@ -48,6 +48,8 @@ add_subdirectory( delaunator )
 add_subdirectory( dxflib_qcad )
 add_subdirectory( dynamic_bitset )
 add_subdirectory( expected )
+set( FASTFLOAT_INSTALL OFF )
+add_subdirectory( fast_float )
 set( FMT_INSTALL OFF )
 add_subdirectory( fmt )
 add_subdirectory( gzip-hpp )