Add argument parsing

Added (IMHO) relatively simple argument parsing function (as well as helper
function for printing help information).

include/BH/Args.h

@@ -0,0 +1,70 @@
+#ifndef BH_ARGS_H
+#define BH_ARGS_H
+
+
+#include "Common.h"
+
+
+#define BH_ARGS_ARGUMENT   0
+#define BH_ARGS_UNKNOWN   -1
+
+#define BH_ARGS_VALUE      1
+#define BH_ARGS_OPTIONAL   2
+
+
+typedef struct BH_ArgsOption
+{
+    int key;
+    const char *name;
+    int flags;
+    const char *description;
+} BH_ArgsOption;
+
+
+typedef int (*BH_ArgsCallback)(int key, char *arg, void *data);
+
+
+/**
+ * Parses command line \a options (given by \a argc and \a argv) and calls the
+ * specified \a callback with \a data.
+ *
+ * There are few internal rules:
+ * - If the "--" argument is specified, option parsing stops, and the rest of
+ *   the arguments are processed as is.
+ * - If the "-" argument is specified, it is processed as is.
+ * - For long options, if a value is required, the string after the equal sign
+ *   or the next argument will be used as the value ("--define=Value" or
+ *   "--define Value").
+ * - For short options, if a value is required, the string after the option
+ *   letter or the next argument will be used as the value ("-DValue" or
+ *   "-D Value").
+ *
+ * Options array should have last element filled with zeros.
+ *
+ * \param argc      Arguments count
+ * \param argv      Arguments array
+ * \param options   Options array pointer
+ * \param callback  Callback function
+ * \param data      Callback data
+ *
+ * \return On success, returns zero value.
+ * \return On failure, returns error code.
+ */
+int BH_ArgsParse(int argc,
+                 char **argv,
+                 BH_ArgsOption *options,
+                 BH_ArgsCallback callback,
+                 void *data);
+
+
+/**
+ * Prints documentation for \a options (with specified \a padding).
+ *
+ * \param options  Options array pointer
+ * \param padding  Padding
+ */
+void BH_ArgsHelp(BH_ArgsOption *options,
+                 int padding);
+
+
+#endif /* BH_ARGS_H */