Use template for DataString

src/rpc.cpp

 #include "sensor_node.h"
 
-DataString::DataString(uint16_t max_length)
-{
-  this->max_length = max_length;
-  this->data = (uint8_t *)malloc(sizeof(uint8_t) * max_length);
-  this->length = 0;
-}
-
-void DataString::reset()
-{
-  this->length = 0;
-}
-
-size_t DataString::write(uint8_t c)
-{
-  this->data[this->length] = c;
-  this->length++;
-}
-
 ArduRPC_SensorNode::ArduRPC_SensorNode(ArduRPC &rpc, char *name) : ArduRPCHandler()
 {
   this->type = 0x9999;
   this->registerSelf(rpc, name, (void *)this);
   this->status = 0;
-  this->cache = new DataString(1024);
 }
 
 uint8_t ArduRPC_SensorNode::call(uint8_t cmd_id)
@@ -44,13 +25,13 @@ uint8_t ArduRPC_SensorNode::call(uint8_t cmd_id)
     this->sensor_uuid[SENSOR_NODE_KEY_MAX_LENGTH] = '\0';
 
     this->status = 2;
-    this->cache->reset();
-    this->cache->print("[");
+    this->cache.reset();
+    this->cache.print("[");
     return RPC_RETURN_SUCCESS;
   } else if (cmd_id == 0x11) {
     /* finish() */
     if(this->status == 2 or this->status == 3) {
-      this->cache->print("]");
+      this->cache.print("]");
     }
     this->status = 4;
     this->submitData();
@@ -76,52 +57,52 @@ uint8_t ArduRPC_SensorNode::call(uint8_t cmd_id)
     if(this->status == 2) {
       this->status = 3;
     } else {
-      this->cache->print(",");
+      this->cache.print(",");
     }
 
-    this->cache->print("[");
+    this->cache.print("[");
     // sensor id
     u8 = this->_rpc->getParam_uint8();
-    this->cache->print(u8);
-    this->cache->print(",");
+    this->cache.print(u8);
+    this->cache.print(",");
     // sensor type
     u16 = this->_rpc->getParam_uint16();
-    this->cache->print(u16);
-    this->cache->print(",");
+    this->cache.print(u16);
+    this->cache.print(",");
     // value type
     u8 = this->_rpc->getParam_uint8();
-    this->cache->print(u8);
-    this->cache->print(",");
+    this->cache.print(u8);
+    this->cache.print(",");
     // value
     // - read value type
     u8 = this->_rpc->getParam_uint8();
     // - read value
     if(u8 == RPC_INT8) {
       i8 = this->_rpc->getParam_int8();
-      this->cache->print(i8);
+      this->cache.print(i8);
     } else if(u8 == RPC_UINT8) {
       u8 = this->_rpc->getParam_uint8();
-      this->cache->print(u8);
+      this->cache.print(u8);
     } else if(u8 == RPC_INT16) {
       i16 = this->_rpc->getParam_int16();
-      this->cache->print(i16);
+      this->cache.print(i16);
     } else if(u8 == RPC_UINT16) {
       u16 = this->_rpc->getParam_uint16();
-      this->cache->print(u16);
+      this->cache.print(u16);
     } else if(u8 == RPC_INT32) {
       i32 = this->_rpc->getParam_int32();
-      this->cache->print(i32);
+      this->cache.print(i32);
     } else if(u8 == RPC_UINT32) {
       u32 = this->_rpc->getParam_uint32();
-      this->cache->print(u32);
+      this->cache.print(u32);
     } else if(u8 == RPC_FLOAT) {
       f = this->_rpc->getParam_float();
-      this->cache->print(f);
+      this->cache.print(f);
     } else {
       // value type not supported
-      this->cache->print("\"n/a\"");
+      this->cache.print("\"n/a\"");
     }
-    this->cache->print("]");
+    this->cache.print("]");
     return RPC_RETURN_SUCCESS;
   }
   return RPC_RETURN_COMMAND_NOT_FOUND;
@@ -153,10 +134,10 @@ void ArduRPC_SensorNode::submitData()
   client->println(this->sensor_key);
   client->print("X-Sensor-Version: 1\r\n");
   client->print("Content-Length: ");
-  client->println(this->cache->length);
+  client->println(this->cache.length);
   client->println();
-  for(i = 0; i < this->cache->length; i++) {
-    Serial.print((char)this->cache->data[i]);
+  for(i = 0; i < this->cache.length; i++) {
+    Serial.print((char)this->cache.data[i]);
   }
   this->status = 0;
   client->stop();

src/sensor_node.h

@@ -34,16 +34,20 @@
 #define SENSOR_NODE_UUID_MAX_LENGTH 64
 #define SENSOR_NODE_KEY_MAX_LENGTH  64
 
+template <uint16_t SIZE>
 class DataString : public Print
 {
   public:
-    DataString(uint16_t);
-    void reset();
-    virtual size_t write(uint8_t);
+    DataString() { this->length = 0; };
+    void reset() { this->length = 0; };
+    virtual size_t write(uint8_t c) {
+      this->data[this->length] = c;
+      this->length++;
+    };
     uint16_t length;
-    uint8_t *data;
+    uint8_t data[SIZE];
   private:
-    uint16_t max_length;
+    uint16_t max_length = SIZE;
 };
 
 class ArduRPC_SensorNode : public ArduRPCHandler
@@ -55,7 +59,7 @@ class ArduRPC_SensorNode : public ArduRPCHandler
     void ICACHE_FLASH_ATTR submitData();
   private:
     uint8_t status;
-    DataString *cache;
+    DataString<1024> cache;
     char sensor_uuid[SENSOR_NODE_UUID_MAX_LENGTH + 1];
     char sensor_key[SENSOR_NODE_UUID_MAX_LENGTH + 1];
 };