1 files changed, 66 insertions, 0 deletions
diff --git a/sys_info_param.hpp b/sys_info_param.hpp
new file mode 100644
index 0000000..6088626
--- /dev/null
+++ b/sys_info_param.hpp
@@ -0,0 +1,66 @@
+#pragma once
+
+#include <cstdint>
+#include <functional>
+#include <map>
+#include <string>
+#include <tuple>
+
+/**
+ * Key-value store for string-type system info parameters.
+ */
+class SysInfoParamStoreIntf
+{
+  public:
+    virtual ~SysInfoParamStoreIntf()
+    {
+    }
+
+    /**
+     * Returns true if parameter is found. If and only if s is non-null,
+     * invokes the parameter's callback and writes the value.
+     *
+     * @param[in] paramSelector - the key to lookup.
+     * @return tuple of bool and string, true if parameter is found and
+     * string set accordingly.
+     */
+    virtual std::tuple<bool, std::string>
+        lookup(uint8_t paramSelector) const = 0;
+
+    /**
+     * Update a parameter by its code with a string value.
+     *
+     * @param[in] paramSelector - the key to update.
+     * @param[in] s - the value to set.
+     */
+    virtual void update(uint8_t paramSelector, const std::string& s) = 0;
+
+    /**
+     * Update a parameter by its code with a callback that is called to retrieve
+     * its value whenever called. Callback must be idempotent, as it may be
+     * called multiple times by the host to retrieve the parameter by chunks.
+     *
+     * @param[in] paramSelector - the key to update.
+     * @param[in] callback - the callback to use for parameter retrieval.
+     */
+    virtual void update(uint8_t paramSelector,
+                        const std::function<std::string()>& callback) = 0;
+
+    // TODO: Store "read-only" flag for each parameter.
+    // TODO: Function to erase a parameter?
+};
+
+/**
+ * Implement the system info parameters store as a map of callbacks.
+ */
+class SysInfoParamStore : public SysInfoParamStoreIntf
+{
+  public:
+    std::tuple<bool, std::string> lookup(uint8_t paramSelector) const override;
+    void update(uint8_t paramSelector, const std::string& s) override;
+    void update(uint8_t paramSelector,
+                const std::function<std::string()>& callback) override;
+
+  private:
+    std::map<uint8_t, std::function<std::string()>> params;
+};