MXS-2304 Convert configuration management structs to classes

The fields of MXS_CONFIG_PARAMETER remain unchanged so that parameter
processing can be changed gradually.

include/maxscale/config.hh

@@ -215,31 +215,56 @@ extern const char CN_LOG_AUGMENTATION[];
 extern const char CN_LOG_TO_SHM[];
 
 /**
- * The config parameter
+ * Config parameter container. Typically includes all parameters of a single configuration file section
+ * such as a server or filter.
  */
-typedef struct config_parameter
+class MXS_CONFIG_PARAMETER
 {
+public:
+
+    /**
+     * Get value of key as string.
+     *
+     * @param key Parameter name
+     * @return Parameter value. Empty string if key not found.
+     */
+    std::string get_string(const std::string& key) const;
+
+    /**
+     * Get value of key as c-string. The pointer is valid as long as the underlying configuration
+     * is not changed.
+     *
+     * @param key Parameter name
+     * @return Parameter value. Empty string if key not found.
+     */
+    const char* get_c_str(const std::string& key) const;
+
+    int64_t get_integer(const std::string& key) const;
+
+    int64_t get_enum(const std::string& key, const MXS_ENUM_VALUE* enum_mapping) const;
+
     char*                    name;          /**< The name of the parameter */
     char*                    value;         /**< The value of the parameter */
-    struct config_parameter* next;          /**< Next pointer in the linked list */
+    MXS_CONFIG_PARAMETER*    next;          /**< Next pointer in the linked list */
-} MXS_CONFIG_PARAMETER;
+};
 
 /**
  * The config context structure, used to build the configuration
  * data during the parse process
  */
-typedef struct config_context
+class CONFIG_CONTEXT
 {
+public:
     char*                  object;          /**< The name of the object being configured */
     MXS_CONFIG_PARAMETER*  parameters;      /**< The list of parameter values */
     bool                   was_persisted;   /**< True if this object was persisted */
-    struct config_context* next;            /**< Next pointer in the linked list */
+    CONFIG_CONTEXT*        next;            /**< Next pointer in the linked list */
-} CONFIG_CONTEXT;
+};
 
 /**
  * The gateway global configuration data
  */
-typedef struct
+struct MXS_CONFIG
 {
     bool    config_check;                               /**< Only check config */
     int     n_threads;                                  /**< Number of polling threads */
@@ -287,7 +312,7 @@ typedef struct
     char             peer_user[MAX_ADMIN_HOST_LEN];     /**< Username for maxscale-to-maxscale traffic */
     char             peer_password[MAX_ADMIN_HOST_LEN]; /**< Password for maxscale-to-maxscale traffic */
     mxb_log_target_t log_target;                        /**< Log type */
-} MXS_CONFIG;
+};
 
 /**
  * @brief Get global MaxScale configuration

server/core/config.cc

@@ -1900,6 +1900,26 @@ bool config_get_compiled_regexes(const MXS_CONFIG_PARAMETER* params,
     return rval;
 }
 
+string MXS_CONFIG_PARAMETER::get_string(const std::string& key) const
+{
+    return get_c_str(key);
+}
+
+const char* MXS_CONFIG_PARAMETER::get_c_str(const std::string& key) const
+{
+    return config_get_string(this, key.c_str());
+}
+
+int64_t MXS_CONFIG_PARAMETER::get_integer(const std::string& key) const
+{
+    return config_get_integer(this, key.c_str());
+}
+
+int64_t MXS_CONFIG_PARAMETER::get_enum(const std::string& key, const MXS_ENUM_VALUE* enum_mapping) const
+{
+    return config_get_enum(this, key.c_str(), enum_mapping);
+}
+
 MXS_CONFIG_PARAMETER* config_clone_param(const MXS_CONFIG_PARAMETER* param)
 {
     MXS_CONFIG_PARAMETER* p2 = (MXS_CONFIG_PARAMETER*)MXS_MALLOC(sizeof(MXS_CONFIG_PARAMETER));