Removed implicit conversion in comparison operators (issue #998)

src/ArduinoJson/Operators/VariantComparisons.hpp

@@ -7,154 +7,216 @@
 #include "../Variant/VariantRef.hpp"
 
 namespace ARDUINOJSON_NAMESPACE {
+
+template <typename T, typename Enable = void>
+struct Comparer;
+
 template <typename T>
-struct is_simple_value {
-  static const bool value = is_integral<T>::value ||
-                            is_floating_point<T>::value ||
-                            is_same<T, bool>::value;
+struct Comparer<T, typename enable_if<IsString<T>::value>::type> {
+  T rhs;
+  int result;
+
+  explicit Comparer(T value) : rhs(value), result(1) {}
+
+  void visitArray(const CollectionData &) {}
+  void visitObject(const CollectionData &) {}
+  void visitFloat(Float) {}
+  void visitString(const char *lhs) {
+    result = -adaptString(rhs).compare(lhs);
+  }
+  void visitRawJson(const char *, size_t) {}
+  void visitNegativeInteger(UInt) {}
+  void visitPositiveInteger(UInt) {}
+  void visitBoolean(bool) {}
+  void visitNull() {
+    result = adaptString(rhs).compare(NULL);
+  }
+};
+
+template <typename T>
+typename enable_if<is_signed<T>::value, int>::type sign(const T &value) {
+  return value < 0 ? -1 : value > 0 ? 1 : 0;
+}
+
+template <typename T>
+typename enable_if<is_unsigned<T>::value, int>::type sign(const T &value) {
+  return value > 0 ? 1 : 0;
+}
+
+template <typename T>
+struct Comparer<T, typename enable_if<is_integral<T>::value ||
+                                      is_floating_point<T>::value>::type> {
+  T rhs;
+  int result;
+
+  explicit Comparer(T value) : rhs(value), result(1) {}
+
+  void visitArray(const CollectionData &) {}
+  void visitObject(const CollectionData &) {}
+  void visitFloat(Float lhs) {
+    result = sign(lhs - static_cast<Float>(rhs));
+  }
+  void visitString(const char *) {}
+  void visitRawJson(const char *, size_t) {}
+  void visitNegativeInteger(UInt lhs) {
+    result = -sign(static_cast<T>(lhs) + rhs);
+  }
+  void visitPositiveInteger(UInt lhs) {
+    result = static_cast<T>(lhs) < rhs ? -1 : static_cast<T>(lhs) > rhs ? 1 : 0;
+  }
+  void visitBoolean(bool) {}
+  void visitNull() {}
+};
+
+template <>
+struct Comparer<bool, void> {
+  bool rhs;
+  int result;
+
+  explicit Comparer(bool value) : rhs(value), result(1) {}
+
+  void visitArray(const CollectionData &) {}
+  void visitObject(const CollectionData &) {}
+  void visitFloat(Float) {}
+  void visitString(const char *) {}
+  void visitRawJson(const char *, size_t) {}
+  void visitNegativeInteger(UInt) {}
+  void visitPositiveInteger(UInt) {}
+  void visitBoolean(bool lhs) {
+    result = static_cast<int>(lhs - rhs);
+  }
+  void visitNull() {}
 };
 
 template <typename TVariant>
 class VariantComparisons {
+ private:
+  template <typename T>
+  static int compare(TVariant lhs, const T &rhs) {
+    Comparer<T> comparer(rhs);
+    lhs.accept(comparer);
+    return comparer.result;
+  }
+
  public:
-  // const char* == TVariant
+  // value == TVariant
   template <typename T>
-  friend typename enable_if<IsString<T *>::value, bool>::type operator==(
-      T *lhs, TVariant rhs) {
-    return adaptString(lhs).equals(rhs.template as<const char *>());
+  friend bool operator==(T *lhs, TVariant rhs) {
+    return compare(rhs, lhs) == 0;
+  }
+  template <typename T>
+  friend bool operator==(const T &lhs, TVariant rhs) {
+    return compare(rhs, lhs) == 0;
   }
 
-  // std::string == TVariant
+  // TVariant == value
   template <typename T>
-  friend typename enable_if<IsString<T>::value, bool>::type operator==(
-      const T &lhs, TVariant rhs) {
-    return adaptString(lhs).equals(rhs.template as<const char *>());
+  friend bool operator==(TVariant lhs, T *rhs) {
+    return compare(lhs, rhs) == 0;
+  }
+  template <typename T>
+  friend bool operator==(TVariant lhs, const T &rhs) {
+    return compare(lhs, rhs) == 0;
   }
 
-  // TVariant == const char*
+  // value != TVariant
   template <typename T>
-  friend typename enable_if<IsString<T *>::value, bool>::type operator==(
-      TVariant lhs, T *rhs) {
-    return adaptString(rhs).equals(lhs.template as<const char *>());
+  friend bool operator!=(T *lhs, TVariant rhs) {
+    return compare(rhs, lhs) != 0;
+  }
+  template <typename T>
+  friend bool operator!=(const T &lhs, TVariant rhs) {
+    return compare(rhs, lhs) != 0;
   }
 
-  // TVariant == std::string
+  // TVariant != value
   template <typename T>
-  friend typename enable_if<IsString<T>::value, bool>::type operator==(
-      TVariant lhs, const T &rhs) {
-    return adaptString(rhs).equals(lhs.template as<const char *>());
+  friend bool operator!=(TVariant lhs, T *rhs) {
+    return compare(lhs, rhs) != 0;
+  }
+  template <typename T>
+  friend bool operator!=(TVariant lhs, const T &rhs) {
+    return compare(lhs, rhs) != 0;
   }
 
-  // bool/int/float == TVariant
+  // value < TVariant
   template <typename T>
-  friend typename enable_if<is_simple_value<T>::value, bool>::type operator==(
-      const T &lhs, TVariant rhs) {
-    return lhs == rhs.template as<T>();
+  friend bool operator<(T *lhs, TVariant rhs) {
+    return compare(rhs, lhs) > 0;
+  }
+  template <typename T>
+  friend bool operator<(const T &lhs, TVariant rhs) {
+    return compare(rhs, lhs) > 0;
   }
 
-  // TVariant == bool/int/float
+  // TVariant < value
   template <typename T>
-  friend typename enable_if<is_simple_value<T>::value, bool>::type operator==(
-      TVariant lhs, const T &rhs) {
-    return lhs.template as<T>() == rhs;
+  friend bool operator<(TVariant lhs, T *rhs) {
+    return compare(lhs, rhs) < 0;
+  }
+  template <typename T>
+  friend bool operator<(TVariant lhs, const T &rhs) {
+    return compare(lhs, rhs) < 0;
   }
 
-  // const char* != TVariant
+  // value <= TVariant
   template <typename T>
-  friend typename enable_if<IsString<T *>::value, bool>::type operator!=(
-      T *lhs, TVariant rhs) {
-    return !adaptString(lhs).equals(rhs.template as<const char *>());
+  friend bool operator<=(T *lhs, TVariant rhs) {
+    return compare(rhs, lhs) >= 0;
+  }
+  template <typename T>
+  friend bool operator<=(const T &lhs, TVariant rhs) {
+    return compare(rhs, lhs) >= 0;
   }
 
-  // std::string != TVariant
+  // TVariant <= value
   template <typename T>
-  friend typename enable_if<IsString<T>::value, bool>::type operator!=(
-      const T &lhs, TVariant rhs) {
-    return !adaptString(lhs).equals(rhs.template as<const char *>());
+  friend bool operator<=(TVariant lhs, T *rhs) {
+    return compare(lhs, rhs) <= 0;
+  }
+  template <typename T>
+  friend bool operator<=(TVariant lhs, const T &rhs) {
+    return compare(lhs, rhs) <= 0;
   }
 
-  // TVariant != const char*
+  // value > TVariant
   template <typename T>
-  friend typename enable_if<IsString<T *>::value, bool>::type operator!=(
-      TVariant lhs, T *rhs) {
-    return !adaptString(rhs).equals(lhs.template as<const char *>());
+  friend bool operator>(T *lhs, TVariant rhs) {
+    return compare(rhs, lhs) < 0;
+  }
+  template <typename T>
+  friend bool operator>(const T &lhs, TVariant rhs) {
+    return compare(rhs, lhs) < 0;
   }
 
-  // TVariant != std::string
+  // TVariant > value
   template <typename T>
-  friend typename enable_if<IsString<T>::value, bool>::type operator!=(
-      TVariant lhs, const T &rhs) {
-    return !adaptString(rhs).equals(lhs.template as<const char *>());
+  friend bool operator>(TVariant lhs, T *rhs) {
+    return compare(lhs, rhs) > 0;
+  }
+  template <typename T>
+  friend bool operator>(TVariant lhs, const T &rhs) {
+    return compare(lhs, rhs) > 0;
   }
 
-  // bool/int/float != TVariant
+  // value >= TVariant
   template <typename T>
-  friend typename enable_if<is_simple_value<T>::value, bool>::type operator!=(
-      const T &lhs, TVariant rhs) {
-    return lhs != rhs.template as<T>();
+  friend bool operator>=(T *lhs, TVariant rhs) {
+    return compare(rhs, lhs) <= 0;
+  }
+  template <typename T>
+  friend bool operator>=(const T &lhs, TVariant rhs) {
+    return compare(rhs, lhs) <= 0;
   }
 
-  // TVariant != bool/int/float
+  // TVariant >= value
   template <typename T>
-  friend typename enable_if<is_simple_value<T>::value, bool>::type operator!=(
-      TVariant lhs, const T &rhs) {
-    return lhs.template as<T>() != rhs;
+  friend bool operator>=(TVariant lhs, T *rhs) {
+    return compare(lhs, rhs) >= 0;
   }
-
-  // bool/int/float < TVariant
   template <typename T>
-  friend typename enable_if<is_simple_value<T>::value, bool>::type operator<(
-      const T &lhs, TVariant rhs) {
-    return lhs < rhs.template as<T>();
-  }
-
-  // TVariant < bool/int/float
-  template <typename T>
-  friend typename enable_if<is_simple_value<T>::value, bool>::type operator<(
-      TVariant lhs, const T &rhs) {
-    return lhs.template as<T>() < rhs;
-  }
-
-  // bool/int/float <= TVariant
-  template <typename T>
-  friend typename enable_if<is_simple_value<T>::value, bool>::type operator<=(
-      const T &lhs, TVariant rhs) {
-    return lhs <= rhs.template as<T>();
-  }
-
-  // TVariant <= bool/int/float
-  template <typename T>
-  friend typename enable_if<is_simple_value<T>::value, bool>::type operator<=(
-      TVariant lhs, const T &rhs) {
-    return lhs.template as<T>() <= rhs;
-  }
-
-  // bool/int/float > TVariant
-  template <typename T>
-  friend typename enable_if<is_simple_value<T>::value, bool>::type operator>(
-      const T &lhs, TVariant rhs) {
-    return lhs > rhs.template as<T>();
-  }
-
-  // TVariant > bool/int/float
-  template <typename T>
-  friend typename enable_if<is_simple_value<T>::value, bool>::type operator>(
-      TVariant lhs, const T &rhs) {
-    return lhs.template as<T>() > rhs;
-  }
-
-  // bool/int/float >= TVariant
-  template <typename T>
-  friend typename enable_if<is_simple_value<T>::value, bool>::type operator>=(
-      const T &lhs, TVariant rhs) {
-    return lhs >= rhs.template as<T>();
-  }
-
-  // TVariant >= bool/int/float
-  template <typename T>
-  friend typename enable_if<is_simple_value<T>::value, bool>::type operator>=(
-      TVariant lhs, const T &rhs) {
-    return lhs.template as<T>() >= rhs;
+  friend bool operator>=(TVariant lhs, const T &rhs) {
+    return compare(lhs, rhs) >= 0;
   }
 };
 

src/ArduinoJson/Polyfills/safe_strcmp.hpp

@@ -0,0 +1,22 @@
+// ArduinoJson - arduinojson.org
+// Copyright Benoit Blanchon 2014-2019
+// MIT License
+
+#pragma once
+
+namespace ARDUINOJSON_NAMESPACE {
+
+inline int8_t safe_strcmp(const char* a, const char* b) {
+  if (a == b) return 0;
+  if (!a) return -1;
+  if (!b) return 1;
+  return static_cast<int8_t>(strcmp(a, b));
+}
+
+inline int8_t safe_strncmp(const char* a, const char* b, size_t n) {
+  if (a == b) return 0;
+  if (!a) return -1;
+  if (!b) return 1;
+  return static_cast<int8_t>(strncmp(a, b, n));
+}
+}  // namespace ARDUINOJSON_NAMESPACE

src/ArduinoJson/Strings/ArduinoStringAdapter.hpp

@@ -5,6 +5,7 @@
 #pragma once
 
 #include <WString.h>
+#include "../Polyfills/safe_strcmp.hpp"
 
 namespace ARDUINOJSON_NAMESPACE {
 
@@ -25,11 +26,14 @@ class ArduinoStringAdapter {
     return !_str->c_str();
   }
 
-  bool equals(const char* expected) const {
+  int8_t compare(const char* other) const {
     // Arduino's String::c_str() can return NULL
-    const char* actual = _str->c_str();
-    if (!actual || !expected) return actual == expected;
-    return 0 == strcmp(actual, expected);
+    const char* me = _str->c_str();
+    return safe_strcmp(me, other);
+  }
+
+  bool equals(const char* expected) const {
+    return compare(expected) == 0;
   }
 
   const char* data() const {

src/ArduinoJson/Strings/ConstRamStringAdapter.hpp

@@ -6,6 +6,7 @@
 
 #include <stddef.h>  // size_t
 #include <string.h>  // strcmp
+#include "../Polyfills/safe_strcmp.hpp"
 
 namespace ARDUINOJSON_NAMESPACE {
 
@@ -13,10 +14,12 @@ class ConstRamStringAdapter {
  public:
   ConstRamStringAdapter(const char* str = 0) : _str(str) {}
 
+  int8_t compare(const char* other) const {
+    return safe_strcmp(_str, other);
+  }
+
   bool equals(const char* expected) const {
-    const char* actual = _str;
-    if (!actual || !expected) return actual == expected;
-    return strcmp(actual, expected) == 0;
+    return compare(expected) == 0;
   }
 
   bool isNull() const {

src/ArduinoJson/Strings/FlashStringAdapter.hpp

@@ -10,10 +10,15 @@ class FlashStringAdapter {
  public:
   FlashStringAdapter(const __FlashStringHelper* str) : _str(str) {}
 
+  int8_t compare(const char* other) const {
+    if (!other && !_str) return 0;
+    if (!_str) return -1;
+    if (!other) return 1;
+    return -strcmp_P(other, reinterpret_cast<const char*>(_str));
+  }
+
   bool equals(const char* expected) const {
-    const char* actual = reinterpret_cast<const char*>(_str);
-    if (!actual || !expected) return actual == expected;
-    return strcmp_P(expected, actual) == 0;
+    return compare(expected) == 0;
   }
 
   bool isNull() const {

src/ArduinoJson/Strings/SizedFlashStringAdapter.hpp

@@ -11,10 +11,15 @@ class SizedFlashStringAdapter {
   SizedFlashStringAdapter(const __FlashStringHelper* str, size_t sz)
       : _str(str), _size(sz) {}
 
+  int8_t compare(const char* other) const {
+    if (!other && !_str) return 0;
+    if (!_str) return -1;
+    if (!other) return 1;
+    return -strncmp_P(other, reinterpret_cast<const char*>(_str), _size);
+  }
+
   bool equals(const char* expected) const {
-    const char* actual = reinterpret_cast<const char*>(_str);
-    if (!actual || !expected) return actual == expected;
-    return strncmp_P(expected, actual, _size) == 0;
+    return compare(expected) == 0;
   }
 
   bool isNull() const {

src/ArduinoJson/Strings/SizedRamStringAdapter.hpp

@@ -12,10 +12,12 @@ class SizedRamStringAdapter {
  public:
   SizedRamStringAdapter(const char* str, size_t n) : _str(str), _size(n) {}
 
+  int8_t compare(const char* other) const {
+    return safe_strncmp(_str, other, _size) == 0;
+  }
+
   bool equals(const char* expected) const {
-    const char* actual = reinterpret_cast<const char*>(_str);
-    if (!actual || !expected) return actual == expected;
-    return strcmp(actual, expected) == 0;
+    return compare(expected) == 0;
   }
 
   bool isNull() const {

src/ArduinoJson/Strings/StlStringAdapter.hpp

@@ -23,6 +23,11 @@ class StlStringAdapter {
     return false;
   }
 
+  int8_t compare(const char* other) const {
+    if (!other) return 1;
+    return static_cast<int8_t>(_str->compare(other));
+  }
+
   bool equals(const char* expected) const {
     if (!expected) return false;
     return *_str == expected;