Added error messages, added cmake options

Now, argparse can be compiled with the support for error messages, which can be obtained via `arg_geterror ()`. If argparse was compiled without the support for error messages, NULL will be returned instead. Added CMake option to compile example.c via `-DARGPARSE_EXAMPLES` option.

Author: slayers-git

CMakeLists.txt

@@ -1,17 +1,32 @@
-cmake_minimum_required (VERSION 3.10)
+cmake_minimum_required (VERSION 3.12)
 project (argparse)
 
 set (CMAKE_C_FLAGS "-O3")
+option (ARGPARSE_ERRORS "builtin error description via arg_geterror ()" OFF)
+option (ARGPARSE_EXAMPLES "build examples" OFF)
 
 set (argparse_h
 	${PROJECT_SOURCE_DIR}/argparse.h)
 set (argparse_c
 	${PROJECT_SOURCE_DIR}/argparse.c)
+set (argparse_example_c
+	${PROJECT_SOURCE_DIR}/example.c)
 add_library (argparse SHARED
+	${argparse_h}
 	${argparse_c})
 
 set_target_properties (argparse PROPERTIES OUTPUT_NAME "argparse")
 
+if (ARGPARSE_ERRORS)
+	target_compile_definitions (argparse PUBLIC ARGPARSE_ERRORS)
+endif()
+
+if (ARGPARSE_EXAMPLES)
+	add_executable (argparse_ex
+		${argparse_example_c})
+	target_link_libraries (argparse_ex argparse)
+endif()
+
 set (LIBRARY_OUTPUT_PATH ${PROJECT_BINARY_DIR}/lib)
 
 install (TARGETS argparse

README.md

@@ -91,3 +91,6 @@ To build and install argparse on \*Unix systems, in your shell type
 mkdir build && cd build\
 cmake .. && make && sudo make install
 ```
+
+To build examples to `cmake` command add `-DARGPARSE_EXAMPLES=1`; to include error messages via `arg_geterror ()` to `cmake` command add `-DARGPARSE_ERRORS=1`
+Note, that if the library is compiled without error messages, a call to `arg_geterror ()` will always return NULL.

argparse.c

@@ -26,6 +26,20 @@
 #	define ARG_INLINE 
 #endif
 
+#ifdef ARGPARSE_ERRORS
+#	define _inc_aerr
+	/* a map with descriptions of all error codes */
+	const char * arg_err_map [] = {
+		[ARG_SUCCESS] = 0x0,
+
+		[ARG_HALT]   = "parsing was halted",
+		[ARG_INVAL]  = "invalid argument",
+		[ARG_UNEXP]  = "unexpected characters are met",
+		[ARG_NMATCH] = "not an argument",
+		[ARG_NVALUE] = "argument does not have a value"
+	};
+#endif
+
 /* A simple implementation of some important "string.h" functions */
 #ifdef ARG_STANDALONE
 #	define ARG_ASSERT(x)
@@ -292,3 +306,11 @@ char * arg_parse (int * argc, char *** argv, arg_list list, char ** nk, size_t *
 
 	return NULL;
 }
+
+const char * arg_geterror (arg_return code) {
+#ifdef _inc_aerr 
+	return arg_err_map [code];
+#else
+	return NULL;
+#endif
+}

argparse.h

@@ -16,13 +16,13 @@
  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA. */
 
 /* Parsing:
- * 	check whether or not the argument belongs in line
- * 	check if its long or short type
+ * 	check whether or not the argument is valid
+ * 	if it is a key, determine is it long or short type
  * 	parse accordingly:
- * 		short, meaning that the data can be inserted after a whitespace
- * 		long, meaning that the data can be inserted after a space char 
+ * 		short, meaning that the data can be inserted after a whitespace or immediately after the key
+ * 		long, meaning that the data can be inserted after a space char
  *
- * 	keys can be merged together, if they are flags (i.e: tar -xzvf ...) or,
+ * 	keys can be merged together if they are flags (i.e: tar -xzvf ...) or,
  * 	if ARG_PARSE_MERGED is passed to the arg_parse function, merged key-value
  * 	arguments can be used (i.e objdump -Mintel ...) */
 
@@ -32,19 +32,33 @@
 
 #include <stddef.h>
 
-#define ARG_SUCCESS 0
+/* For windows compatibility */
+#if defined(_WIN32) || defined(__WIN32__)
+#	if defined(argparse_EXPORTS) /* should be added by cmake */
+#		define  ARGPARSE_API __declspec(dllexport)
+#	else
+#		define  ARGPARSE_API __declspec(dllimport)
+#	endif
+#elif defined(linux) || defined(__linux)
+#	define ARGPARSE_API
+#endif
 
-#define ARG_ZERO   -1
-#define ARG_INVAL  -2
-#define ARG_NFOUND -3
-#define ARG_HALT   -4
-#define ARG_UNEXP  -5
-#define ARG_NMATCH -6
-#define ARG_NVALUE -7
+#ifdef __cplusplus
+extern "C" {
+#endif
 
 /* Type for the return codes */
-typedef signed char arg_return;
+typedef enum {
+	ARG_SUCCESS = 0, /* everything is ok */
 
+	ARG_INVAL, /* invalid arguments given */
+	ARG_HALT,  /* halted by the parser (flag) */
+	ARG_UNEXP, /* unexpected characters are met (garbage input) */
+	ARG_NMATCH,/* no match found */
+	ARG_NVALUE /* no value passed to the argument*/
+} arg_return;
+
+/* Prototype for the arg_handler */
 typedef arg_return p_arg_handler (char * data_ptr, size_t blksize, void * retval);
 
 /* The handler is the parser for the value of the argument
@@ -60,19 +74,19 @@ p_arg_handler arg_string_handler;
 p_arg_handler arg_strcpy_handler;
 
 /* Defaults */
-#define ARG_FLAG_DEFAULT   0x0
+#define ARG_FLAG_DEFAULT  0
 /* This flag tells the parser to set the flag argument value to 0 instead of 1 */
-#define ARG_FLAG_UNSET    0x01
+#define ARG_FLAG_UNSET    (1 << 1)
 /* This flag tells the parser that the value for this argument is optional */
-#define ARG_FLAG_OPTIONAL 0x04
+#define ARG_FLAG_OPTIONAL (1 << 2)
 /* This flag tells the parser to stop when the argument is met and parsed */
-#define ARG_FLAG_HALT     0x08
+#define ARG_FLAG_HALT     (1 << 3)
 
 /* Global parser flags */
 /* Defaults */
-#define ARG_PARSE_DEFAULT   0x0
+#define ARG_PARSE_DEFAULT  0
 /* Allow merged arguments (i.e: objdump -Mintel ...) */
-#define ARG_PARSE_MERGED   0x01
+#define ARG_PARSE_MERGED   1
 
 /* Flags define the behaviour of the arguments parser 
  * As example, ARG_FLAG_HALT will cause parser to be stopped when 
@@ -126,6 +140,24 @@ typedef struct arg_argument arg_list[];
  *     continue parsing.
  *   2 this function changes the addresses of the pointers, to save them
  *     as they were, consider writing them into another set of variables. */
-char * arg_parse (int * argc, char *** argv, arg_list list, char ** not_keys, size_t * not_keys_size, arg_flags flags, arg_return * return_code);
+ARGPARSE_API char * arg_parse (int * argc, char *** argv, arg_list list, char ** not_keys, size_t * not_keys_size, arg_flags flags, arg_return * return_code);
+
+/* const char * arg_geterror:
+ *   @param code:
+ *     the code of the error
+ *   RETURN const char * err:
+ *     returns the string with a description of the error code 
+ *   NOTES:
+ *   1 this function does not do bound checking, if an arbitrary code
+ *     is passed, an undefined behavior will occur.
+ *   2 if argparse was compiled with ARGPARSE_ERRORS turned off, the
+ *     function will always return NULL. */
+ARGPARSE_API const char * arg_geterror (arg_return code);
+
+#ifdef __cplusplus
+}
+#endif
+
+#undef ARGPARSE_API
 
 #endif

example.c

@@ -36,7 +36,7 @@ static char op = undef;
  * 
  * handlers modify the value of the argument
  * to write it in retval the right way */
-arg_return custom_enum_handler (void * data, size_t size, void * retval) {
+arg_return custom_enum_handler (char * data, size_t size, void * retval) {
 	if (STREQ (data, "+")) {
 		op = plus;
 	}
@@ -114,7 +114,7 @@ int main (int argc, char ** argv) {
 			return 0;
 		}
 		/* if an error occured */
-		printf ("Could not parse argument: %s\n", err_arg);
+		printf ("Could not parse argument: %s [%s]\n", err_arg, arg_geterror (code));
 		return 1;
 	}