Extract string->double and double->string conversions for use in the preparser.

src/conversions.h

 // Copyright 2011 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 10 matching lines @@
 // SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
 // LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 // DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 // THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 // (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 // OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 
 #ifndef V8_CONVERSIONS_H_
 #define V8_CONVERSIONS_H_
 
+#include <limits>
+
 #include "scanner-base.h"
 
 namespace v8 {
 namespace internal {
 
+// Maximum number of significant digits in decimal representation.
+// The longest possible double in decimal representation is
+// (2^53 - 1) * 2 ^ -1074 that is (2 ^ 53 - 1) * 5 ^ 1074 / 10 ^ 1074
+// (768 digits). If we parse a number whose first digits are equal to a
+// mean of 2 adjacent doubles (that could have up to 769 digits) the result
+// must be rounded to the bigger one unless the tail consists of zeros, so
+// we don't need to preserve all the digits.
+const int kMaxSignificantDigits = 772;
+
+static const double JUNK_STRING_VALUE =
+    std::numeric_limits<double>::quiet_NaN();
+
+static bool isDigit(int x, int radix) {
+  return (x >= '0' && x <= '9' && x < '0' + radix)
+      || (radix > 10 && x >= 'a' && x < 'a' + radix - 10)
+      || (radix > 10 && x >= 'A' && x < 'A' + radix - 10);
+}
+
+
+static double SignedZero(bool negative) {
+  return negative ? -0.0 : 0.0;
+}
+
 
 // The fast double-to-(unsigned-)int conversion routine does not guarantee
 // rounding towards zero.
 // The result is unspecified if x is infinite or NaN, or if the rounded
 // integer value is outside the range of type int.
 static inline int FastD2I(double x) {
   // The static_cast convertion from double to int used to be slow, but
   // as new benchmarks show, now it is much faster than lrint().
   return static_cast<int>(x);
 }
@@ skipping 34 matching lines @@
 // Enumeration for allowing octals and ignoring junk when converting
 // strings to numbers.
 enum ConversionFlags {
   NO_FLAGS = 0,
   ALLOW_HEX = 1,
   ALLOW_OCTALS = 2,
   ALLOW_TRAILING_JUNK = 4
 };
 
 
-// Convert from Number object to C integer.
-static inline int32_t NumberToInt32(Object* number);
-static inline uint32_t NumberToUint32(Object* number);
-
-
 // Converts a string into a double value according to ECMA-262 9.3.1
 double StringToDouble(UnicodeCache* unicode_cache,
-                      String* str,
-                      int flags,
-                      double empty_string_val = 0);
-double StringToDouble(UnicodeCache* unicode_cache,
                       Vector<const char> str,
                       int flags,
                       double empty_string_val = 0);
 double StringToDouble(UnicodeCache* unicode_cache,
                       Vector<const uc16> str,
                       int flags,
                       double empty_string_val = 0);
 // This version expects a zero-terminated character array.
 double StringToDouble(UnicodeCache* unicode_cache,
                       const char* str,
                       int flags,
                       double empty_string_val = 0);
 
-// Converts a string into an integer.
-double StringToInt(UnicodeCache* unicode_cache, String* str, int radix);
-
 // Converts a double to a string value according to ECMA-262 9.8.1.
 // The buffer should be large enough for any floating point number.
 // 100 characters is enough.
 const char* DoubleToCString(double value, Vector<char> buffer);
 
 // Convert an int to a null-terminated string. The returned string is
 // located inside the buffer, but not necessarily at the start.
 const char* IntToCString(int n, Vector<char> buffer);
 
 // Additional number to string conversions for the number type.
 // The caller is responsible for calling free on the returned pointer.
 char* DoubleToFixedCString(double value, int f);
 char* DoubleToExponentialCString(double value, int f);
 char* DoubleToPrecisionCString(double value, int f);
 char* DoubleToRadixCString(double value, int radix);
 
 } }  // namespace v8::internal
 
 #endif  // V8_CONVERSIONS_H_