Changeset 51168 in webkit for trunk/JavaScriptCore/wtf/dtoa.cpp

Timestamp:

Nov 18, 2009, 7:12:50 PM (16 years ago)

Author:

[email protected]

Message:

2009-11-18 Kent Tamura <​[email protected]>

Reviewed by Darin Adler.

Move UString::from(double) implementation to new
WTF::doubleToStringInJavaScriptFormat(), and expose it because WebCore
code will use it.
​https://bugs.webkit.org/show_bug.cgi?id=31330

• Introduce new function createRep(const char*, unsigned) and UString::UString(const char*, unsigned) to reduce 2 calls to strlen().
• Fix a bug that dtoa() doesn't update *rve if the input value is NaN or Infinity.

No new tests because this doesn't change the behavior.

• JavaScriptCore.exp:
• JavaScriptCore.vcproj/JavaScriptCore/JavaScriptCore.def:
• runtime/UString.cpp: (JSC::createRep): (JSC::UString::UString): (JSC::UString::from): Move the code to doubleToStringInJavaScriptFormat().
• runtime/UString.h:
• wtf/dtoa.cpp: (WTF::dtoa): Fix a bug about rve. (WTF::append): A helper for doubleToStringInJavaScriptFormat(). (WTF::doubleToStringInJavaScriptFormat): Move the code from UString::from(double).
• wtf/dtoa.h:

File:

• trunk/JavaScriptCore/wtf/dtoa.cpp (modified) (5 diffs)

trunk/JavaScriptCore/wtf/dtoa.cpp

@@ -149 +149 @@
 #include <wtf/Assertions.h>
 #include <wtf/FastMalloc.h>
+#include <wtf/MathExtras.h>
 #include <wtf/Vector.h>
 #include <wtf/Threading.h>
@@ -1870 +1871 @@
  */
 
-void dtoa(char* result, double dd, int ndigits, int* decpt, int* sign, char** rve)
+void dtoa(DtoaBuffer result, double dd, int ndigits, int* decpt, int* sign, char** rve)
 {
     /*
@@ -1909 +1910 @@
         /* Infinity or NaN */
         *decpt = 9999;
-        if (!word1(&u) && !(word0(&u) & 0xfffff))
+        if (!word1(&u) && !(word0(&u) & 0xfffff)) {
             strcpy(result, "Infinity");
-        else 
+            if (rve)
+                *rve = result + 8;
+        } else {
             strcpy(result, "NaN");
+            if (rve)
+                *rve = result + 3;
+        }
         return;
     }
@@ -1919 +1925 @@
         result[0] = '0';
         result[1] = '\0';
+        if (rve)
+            *rve = result + 1;
         return;
     }
@@ -2377 +2385 @@
 }
 
+static ALWAYS_INLINE void append(char*& next, const char* src, unsigned size)
+{
+    for (unsigned i = 0; i < size; ++i)
+        *next++ = *src++;
+}
+
+void doubleToStringInJavaScriptFormat(double d, DtoaBuffer buffer, unsigned* resultLength)
+{
+    ASSERT(buffer);
+
+    // avoid ever printing -NaN, in JS conceptually there is only one NaN value
+    if (isnan(d)) {
+        append(buffer, "NaN", 3);
+        if (resultLength)
+            *resultLength = 3;
+        return;
+    }
+    // -0 -> "0"
+    if (!d) {
+        buffer[0] = '0';
+        if (resultLength)
+            *resultLength = 1;
+        return;
+    }
+
+    int decimalPoint;
+    int sign;
+
+    DtoaBuffer result;
+    char* resultEnd = 0;
+    WTF::dtoa(result, d, 0, &decimalPoint, &sign, &resultEnd);
+    int length = resultEnd - result;
+
+    char* next = buffer;
+    if (sign)
+        *next++ = '-';
+
+    if (decimalPoint <= 0 && decimalPoint > -6) {
+        *next++ = '0';
+        *next++ = '.';
+        for (int j = decimalPoint; j < 0; j++)
+            *next++ = '0';
+        append(next, result, length);
+    } else if (decimalPoint <= 21 && decimalPoint > 0) {
+        if (length <= decimalPoint) {
+            append(next, result, length);
+            for (int j = 0; j < decimalPoint - length; j++)
+                *next++ = '0';
+        } else {
+            append(next, result, decimalPoint);
+            *next++ = '.';
+            append(next, result + decimalPoint, length - decimalPoint);
+        }
+    } else if (result[0] < '0' || result[0] > '9')
+        append(next, result, length);
+    else {
+        *next++ = result[0];
+        if (length > 1) {
+            *next++ = '.';
+            append(next, result + 1, length - 1);
+        }
+
+        *next++ = 'e';
+        *next++ = (decimalPoint >= 0) ? '+' : '-';
+        // decimalPoint can't be more than 3 digits decimal given the
+        // nature of float representation
+        int exponential = decimalPoint - 1;
+        if (exponential < 0)
+            exponential = -exponential;
+        if (exponential >= 100)
+            *next++ = static_cast<char>('0' + exponential / 100);
+        if (exponential >= 10)
+            *next++ = static_cast<char>('0' + (exponential % 100) / 10);
+        *next++ = static_cast<char>('0' + exponential % 10);
+    }
+    if (resultLength)
+        *resultLength = next - buffer;
+}
+
 } // namespace WTF