replaced String by char* + StringBuilder

settings.cpp

@@ -25,7 +25,7 @@ Settings::~Settings()
 {
 }
 
-void Settings::add_line(String const& section, String const& key, String const& val)
+void Settings::add_line(char const* section, char const* key, char const* val)
 {
     //TODO: do something with the line
     Serial.print("Section: \"");
@@ -35,6 +35,10 @@ void Settings::add_line(String const& section, String const& key, String const&
     Serial.print("\", Val: \"");
     Serial.print(val);
     Serial.println("\"");
+
+    delete[] section;
+    delete[] key;
+    delete[] val;
 }
 
 Settings const* Settings::load(char const* settings_filename)
@@ -62,9 +66,9 @@ Settings const* Settings::load(char const* settings_filename)
     bool is_section_line = false;
     unsigned int nb_whitespace = 0; //used for trimming the end of lines
 
-    String current_section = "";
-    String current_key = "";
-    String current_val = "";
+    StringBuilder current_section;
+    StringBuilder current_key;
+    StringBuilder current_val;
 
     bool write_to_key = true;
 
@@ -89,7 +93,7 @@ Settings const* Settings::load(char const* settings_filename)
             else if (c == '[')
             {
                 is_section_line = true;
-                current_section = "";
+                current_section.clear();
                 continue;
             }
         }
@@ -100,10 +104,12 @@ Settings const* Settings::load(char const* settings_filename)
             is_comment_line = false;
             is_section_line = false;
 
-            settings->add_line(current_section, current_key, current_val);
+            settings->add_line(current_section.to_string(),
+                               current_key.to_string(),
+                               current_val.to_string());
 
-            current_key = "";
-            current_val = "";
+            current_key.clear();
+            current_val.clear();
             write_to_key = true;
         }
         else if(is_comment_line)
@@ -142,7 +148,9 @@ Settings const* Settings::load(char const* settings_filename)
         }
     }
     if(!first_char_of_line && !is_comment_line && !is_section_line)
-        settings->add_line(current_section, current_key, current_val);
+        settings->add_line(current_section.to_string(),
+                           current_key.to_string(),
+                           current_val.to_string());
 
     file.close();
 

settings.h

@@ -1,7 +1,7 @@
 #ifndef SETTINGS_H
 #define SETTINGS_H
 
-#include "Arduino.h"
+#include "string_builder.h"
 #include "wifi_settings.h"
 #include "clock_settings.h"
 
@@ -11,7 +11,9 @@ class Settings
         Settings();
         ~Settings();
 
-        void add_line(String const& section, String const& key, String const& val);
+        void add_line(char const* section,
+                      char const* key,
+                      char const* val);
 
     public:
         static Settings const* load(char const* settings_filename);

string_builder.cpp

@@ -0,0 +1,62 @@
+#include "string_builder.h"
+
+StringBuilder::StringBuilder():
+    m_size(0),
+    m_front(nullptr)
+{
+}
+
+StringBuilder::~StringBuilder()
+{
+    if(m_front != nullptr)
+        delete m_front;
+}
+
+void StringBuilder::clear()
+{
+    if(m_front != nullptr)
+        delete m_front;
+    m_front = nullptr;
+
+    m_size = 0;
+}
+
+bool StringBuilder::empty() const
+{
+    return m_size == 0;
+}
+
+void StringBuilder::append(char const c)
+{
+    ++m_size;
+    Node* new_front = new Node(m_front, c);
+    m_front = new_front;
+}
+
+char* StringBuilder::to_string() const
+{
+    char* ret = new char[m_size + 1];
+    if(ret == nullptr)
+        return ret;
+
+    //populating the string in reverse
+    //because m_front is the last char of the string
+    ret[m_size] = '\0';
+    unsigned int i = m_size - 1;
+    for(Node const* it = m_front; it != nullptr; it = it->next())
+        ret[i--] = it->getChar();
+
+    return ret;
+}
+
+StringBuilder::Node::Node(Node* next, char c):
+    m_next(next),
+    m_c(c)
+{
+}
+
+StringBuilder::Node::~Node()
+{
+    if(m_next != nullptr)
+        delete m_next;
+}

string_builder.h

@@ -0,0 +1,63 @@
+/**
+ * @file string_builder.h
+ * @author n0m1s
+ */
+#ifndef STRING_BUILDER_H
+#define STRING_BUILDER_H
+
+/**
+ * @brief Object used to create string by appending chars without re-allocations
+ */
+class StringBuilder
+{
+    public:
+        StringBuilder();
+        ~StringBuilder();
+
+        /**
+         * @brief empties everything and go back to an empty string
+         */
+        void clear();
+
+        /**
+         * @return true if this is empty
+         */
+        bool empty() const;
+
+        /**
+         * @brief appends a character
+         */
+        void append(char const c);
+        inline void operator += (char const c) {this-> append(c);}
+
+        /**
+         * @brief get the string
+         *
+         * @return a dynamically allocated string (be sure to delete it afterwards)
+         */
+        char* to_string() const;
+
+    protected:
+        /**
+         * @brief Class used to simulate a std::forward_list
+         */
+        class Node
+        {
+            public:
+                Node(Node* next, char c);
+                ~Node();
+
+                inline char getChar() const {return m_c;}
+                inline Node const* next() const {return m_next;}
+
+            protected:
+                Node* m_next;
+                char  m_c;
+        };
+
+    protected:
+        unsigned int m_size;
+        Node * m_front;
+};
+
+#endif //STRING_BUILDER_H