StringToDouble rewritten not using String::Get and memory allocations....

test/cctest/test-conversions.cc

Index: test/cctest/test-conversions.cc
===================================================================
--- test/cctest/test-conversions.cc	(revision 4210)
+++ test/cctest/test-conversions.cc	(working copy)
@@ -41,6 +41,10 @@
   CHECK_EQ(7.0, StringToDouble("07", ALLOW_HEX));
   CHECK_EQ(10.0, StringToDouble("010", ALLOW_HEX));
   CHECK_EQ(77.0, StringToDouble("077", ALLOW_HEX));
+
+  const double x = 010000000000;  // Power of 2, no rounding errors.
+  CHECK_EQ(x * x * x * x * x, StringToDouble("01" "0000000000" "0000000000"
+      "0000000000" "0000000000" "0000000000", ALLOW_OCTALS));
 }
 
 
@@ -80,6 +84,8 @@
 TEST(TrailingJunk) {
   CHECK_EQ(8.0, StringToDouble("8q", ALLOW_TRAILING_JUNK));
   CHECK_EQ(63.0, StringToDouble("077qqq", ALLOW_OCTALS | ALLOW_TRAILING_JUNK));
+  CHECK_EQ(10.0, StringToDouble("10e", ALLOW_OCTALS | ALLOW_TRAILING_JUNK));
+  CHECK_EQ(10.0, StringToDouble("10e-", ALLOW_OCTALS | ALLOW_TRAILING_JUNK));
 }
 
 
@@ -91,6 +97,79 @@
   CHECK_EQ(0.0, StringToDouble(" ", NO_FLAGS));
 }
 
+TEST(IntegerStrLiteral) {
+  CHECK_EQ(0.0, StringToDouble("0.0", NO_FLAGS));
+  CHECK_EQ(0.0, StringToDouble("0", NO_FLAGS));
+  CHECK_EQ(0.0, StringToDouble("00", NO_FLAGS));
+  CHECK_EQ(0.0, StringToDouble("000", NO_FLAGS));
+  CHECK_EQ(1.0, StringToDouble("1", NO_FLAGS));
+  CHECK_EQ(-1.0, StringToDouble("-1", NO_FLAGS));
+  CHECK_EQ(-1.0, StringToDouble("  -  1  ", NO_FLAGS));
+  CHECK_EQ(1.0, StringToDouble("  +  1  ", NO_FLAGS));
+}
+
+TEST(LongNumberStr) {
+  CHECK_EQ(1e10, StringToDouble("1" "0000000000", NO_FLAGS));
+  CHECK_EQ(1e20, StringToDouble("1" "0000000000" "0000000000", NO_FLAGS));
+
+  CHECK_EQ(1e60, StringToDouble("1" "0000000000" "0000000000" "0000000000"
+      "0000000000" "0000000000" "0000000000", NO_FLAGS));
+
+  CHECK_EQ(1e-2, StringToDouble("." "0" "1", NO_FLAGS));
+  CHECK_EQ(1e-11, StringToDouble("." "0000000000" "1", NO_FLAGS));
+  CHECK_EQ(1e-21, StringToDouble("." "0000000000" "0000000000" "1", NO_FLAGS));
+
+  CHECK_EQ(1e-61, StringToDouble("." "0000000000" "0000000000" "0000000000"
+      "0000000000" "0000000000" "0000000000" "1", NO_FLAGS));
+
+
+  // x = 24414062505131248.0 and y = 24414062505131252.0 are representable in
+  // double. Check chat z = (x + y) / 2 is rounded to x...
+  CHECK_EQ(24414062505131248.0,
+           StringToDouble("24414062505131250.0", NO_FLAGS));
+
+  // ... and z = (x + y) / 2 + delta is rounded to y.
+  CHECK_EQ(24414062505131252.0,
+           StringToDouble("24414062505131250.000000001", NO_FLAGS));
+}
+
+
+TEST(MaximumSignificantDigits) {
+  // Smallest possible double
+  double min_double = 1 * pow(2, -1023) * pow(2, -51);
+  CHECK_NE(min_double, 0.0);
+  CHECK_EQ(min_double / 2, 0.0);
+
+  // Maximum odd double (any breater number is rounded to even).
+  double big_num = (pow(2, 52) - 1) * 2.0 + 1.0;
+  CHECK_NE(big_num, big_num - 1.0);
+
+  // Numbers with longest possible decimal representation.
+  long double a = min_double * big_num;
+  long double b = min_double * (big_num - 1);
+
+  char buffer[1100];
+  // Construct a number exactly at the middle between 2 possible
+  // doubles with long decimal representation (~760 significant digits).
+  int n = snprintf(buffer, sizeof(buffer), "%.1000Le", (a + b) / 2);

[Florian Loitsch, 2010/03/25 13:51:35]

It is (imho) better not to rely on snprintf. Precomputing the string and pasting
it here will use up more than 10 lines, but at least there would be no
dependency on sprintf. Also it is not certain that sprintf behaves correctly on
all platforms (for instance on embedded devices).

+
+  CHECK_EQ(strcmp(buffer + n - 10, "00000e-308"), 0);
+  CHECK_EQ(b, StringToDouble(buffer, NO_FLAGS));
+
+  buffer[n - 8] = '1';
+  CHECK_EQ(a, StringToDouble(buffer, NO_FLAGS));
+}
+
+
+TEST(ExponentNumberStr) {
+  CHECK_EQ(1e1, StringToDouble("1e1", NO_FLAGS));
+  CHECK_EQ(1e1, StringToDouble("1e+1", NO_FLAGS));
+  CHECK_EQ(1e-1, StringToDouble("1e-1", NO_FLAGS));
+  CHECK_EQ(1e100, StringToDouble("1e+100", NO_FLAGS));
+  CHECK_EQ(1e-100, StringToDouble("1e-100", NO_FLAGS));
+  CHECK_EQ(1e-106, StringToDouble(".000001e-100", NO_FLAGS));
+}
+
 class OneBit1: public BitField<uint32_t, 0, 1> {};
 class OneBit2: public BitField<uint32_t, 7, 1> {};
 class EightBit1: public BitField<uint32_t, 0, 8> {};