From b29acfb90d1f8714d721e2e322eb349cfca04ccc Mon Sep 17 00:00:00 2001
From: miloyip <miloyip@gmail.com>
Date: Mon, 15 Sep 2014 15:54:15 +0800
Subject: [PATCH] Limit significand to 17 digits for fast path

Should fix gcc debug error in tranvis. May need further refactoring.
---
 include/rapidjson/internal/strtod.h |  4 ++--
 include/rapidjson/reader.h          | 29 +++++++++++++++++++++++------
 2 files changed, 25 insertions(+), 8 deletions(-)

diff --git a/include/rapidjson/internal/strtod.h b/include/rapidjson/internal/strtod.h
index 46248bc..939cadb 100644
--- a/include/rapidjson/internal/strtod.h
+++ b/include/rapidjson/internal/strtod.h
@@ -447,12 +447,11 @@ inline int CheckWithinHalfULP(double b, const BigInteger& d, int dExp, bool* adj
     return cmp;
 }
 
-inline double FullPrecision(double d, int dExp, const char* decimals, size_t length) {
+inline double FullPrecision(double d, int p, const char* decimals, size_t length, size_t decimalPosition, int exp) {
     RAPIDJSON_ASSERT(d >= 0.0);
 
     // Use fast path for string-to-double conversion if possible
     // see http://www.exploringbinary.com/fast-path-decimal-to-floating-point-conversion/
-    int p = dExp;
     if (p > 22) {
         if (p < 22 + 16) {
             // Fast Path Cases In Disguise
@@ -468,6 +467,7 @@ inline double FullPrecision(double d, int dExp, const char* decimals, size_t len
         return 0.0;
 
     const BigInteger dInt(decimals, length);
+    const int dExp = (int)decimalPosition - (int)length + exp;
     Double approx = NormalPrecision(d, p);
     for (int i = 0; i < 10; i++) {
         bool adjustToNegative;
diff --git a/include/rapidjson/reader.h b/include/rapidjson/reader.h
index 17faff8..c03a4ce 100644
--- a/include/rapidjson/reader.h
+++ b/include/rapidjson/reader.h
@@ -779,6 +779,7 @@ private:
         unsigned i = 0;
         uint64_t i64 = 0;
         bool use64bit = false;
+        int significandDigit = 0;
         if (s.Peek() == '0') {
             i = 0;
             s.TakePush();
@@ -796,6 +797,7 @@ private:
                         }
                     }
                     i = i * 10 + static_cast<unsigned>(s.TakePush() - '0');
+                    significandDigit++;
                 }
             else
                 while (s.Peek() >= '0' && s.Peek() <= '9') {
@@ -807,6 +809,7 @@ private:
                         }
                     }
                     i = i * 10 + static_cast<unsigned>(s.TakePush() - '0');
+                    significandDigit++;
                 }
         }
         else
@@ -825,6 +828,7 @@ private:
                             break;
                         }
                     i64 = i64 * 10 + static_cast<unsigned>(s.TakePush() - '0');
+                    significandDigit++;
                 }
             else
                 while (s.Peek() >= '0' && s.Peek() <= '9') {                    
@@ -835,6 +839,7 @@ private:
                             break;
                         }
                     i64 = i64 * 10 + static_cast<unsigned>(s.TakePush() - '0');
+                    significandDigit++;
                 }
         }
 
@@ -849,8 +854,13 @@ private:
 
         // Parse frac = decimal-point 1*DIGIT
         int expFrac = 0;
+        size_t decimalPosition;
         if (s.Peek() == '.') {
             s.Take();
+            decimalPosition = s.Length();
+
+            if (!(s.Peek() >= '0' && s.Peek() <= '9'))
+                RAPIDJSON_PARSE_ERROR(kParseErrorNumberMissFraction, s.Tell());
 
             if (!useDouble) {
 #if RAPIDJSON_64BIT
@@ -864,6 +874,8 @@ private:
                     else {
                         i64 = i64 * 10 + static_cast<unsigned>(s.TakePush() - '0');
                         --expFrac;
+                        if (i64 != 0)
+                            significandDigit++;
                     }
                 }
 
@@ -876,13 +888,18 @@ private:
             }
 
             while (s.Peek() >= '0' && s.Peek() <= '9') {
-                d = d * 10.0 + (s.TakePush() - '0');
-                --expFrac;
+                if (significandDigit < 17) {
+                    d = d * 10.0 + (s.TakePush() - '0');
+                    --expFrac;
+                    if (d != 0.0)
+                        significandDigit++;
+                }
+                else
+                    s.TakePush();
             }
-
-            if (expFrac == 0)
-                RAPIDJSON_PARSE_ERROR(kParseErrorNumberMissFraction, s.Tell());
         }
+        else
+            decimalPosition = s.Length(); // decimal position at the end of integer.
 
         // Parse exp = e [ minus / plus ] 1*DIGIT
         int exp = 0;
@@ -924,7 +941,7 @@ private:
         if (useDouble) {
             int p = exp + expFrac;
             if (parseFlags & kParseFullPrecisionFlag)
-                d = internal::FullPrecision(d, p, decimal, length);
+                d = internal::FullPrecision(d, p, decimal, length, decimalPosition, exp);
             else
                 d = internal::NormalPrecision(d, p);