Added custom implementation of strtod() (issue #453)

include/ArduinoJson/Polyfills/parseFloat.hpp

@@ -0,0 +1,87 @@
+// Copyright Benoit Blanchon 2014-2017
+// MIT License
+//
+// Arduino JSON library
+// https://github.com/bblanchon/ArduinoJson
+// If you like this project, please add a star!
+
+#pragma once
+
+#include "../TypeTraits/FloatTraits.hpp"
+#include "./ctype.hpp"
+#include "./math.hpp"
+
+namespace ArduinoJson {
+namespace Polyfills {
+
+template <typename T>
+inline T parseFloat(const char* s) {
+  typedef TypeTraits::FloatTraits<T> traits;
+  typedef typename traits::mantissa_type mantissa_t;
+  typedef typename traits::exponent_type exponent_t;
+
+  bool negative_result = false;
+  switch (*s) {
+    case '-':
+      negative_result = true;
+    case '+':
+      s++;
+  }
+
+  if (*s == 'n' || *s == 'N') return traits::nan();
+  if (*s == 'i' || *s == 'I')
+    return negative_result ? -traits::inf() : traits::inf();
+
+  mantissa_t mantissa = 0;
+  exponent_t exponent_offset = 0;
+
+  while (isdigit(*s)) {
+    if (mantissa < traits::mantissa_max / 10)
+      mantissa = mantissa * 10 + (*s - '0');
+    else
+      exponent_offset++;
+    s++;
+  }
+
+  if (*s == '.') {
+    s++;
+    while (isdigit(*s)) {
+      if (mantissa < traits::mantissa_max / 10) {
+        mantissa = mantissa * 10 + (*s - '0');
+        exponent_offset--;
+      }
+      s++;
+    }
+  }
+
+  int exponent = 0;
+  if (*s == 'e' || *s == 'E') {
+    s++;
+    bool negative_exponent = false;
+    if (*s == '-') {
+      negative_exponent = true;
+      s++;
+    } else if (*s == '+') {
+      s++;
+    }
+
+    while (isdigit(*s)) {
+      exponent = exponent * 10 + (*s - '0');
+      if (exponent + exponent_offset > traits::exponent_max) {
+        if (negative_exponent)
+          return negative_result ? -0.0f : 0.0f;
+        else
+          return negative_result ? -traits::inf() : traits::inf();
+      }
+      s++;
+    }
+    if (negative_exponent) exponent = -exponent;
+  }
+  exponent += exponent_offset;
+
+  T result = traits::make_float(static_cast<T>(mantissa), exponent);
+
+  return negative_result ? -result : result;
+}
+}
+}