From f77e5a5ec7f8b1373eeda0ea56f47137daf40330 Mon Sep 17 00:00:00 2001 From: Garrett D'Amore Date: Sat, 4 Jan 2025 17:57:28 -0800 Subject: args: Convert nng_opts_parse into a header only library using `nng_args_parse`. The API is identical, except that some names have changed, and this is now a header library in `nng/args.h` - so the core library does not need to carry this code in binaries. Being a header library also means it is not necessary to link against NNG, and it does not include any parts of NNG; it only depends on a standard C99 or C11 environment. --- docs/ref/api/cmd_opts.md | 165 ----------------------------------------------- 1 file changed, 165 deletions(-) delete mode 100644 docs/ref/api/cmd_opts.md (limited to 'docs/ref/api/cmd_opts.md') diff --git a/docs/ref/api/cmd_opts.md b/docs/ref/api/cmd_opts.md deleted file mode 100644 index c28d3f89..00000000 --- a/docs/ref/api/cmd_opts.md +++ /dev/null @@ -1,165 +0,0 @@ -# Command Options - -Some _NNG_ utilities need to parse command line options, -and the supplementary function here allows applications that -need the same support to benefit from this. - -To make use of this, the supplemental header `` -must be included. - -## Parse Command Line Options - -```c -typedef struct nng_optspec { - const char *o_name; // Long style name (may be NULL for short only) - int o_short; // Short option (no clustering!) - int o_val; // Value stored on a good parse (>0) - bool o_arg; // Option takes an argument if true -} nng_optspec; - -int nng_opts_parse(int argc, char *const *argv, - const nng_optspec *spec, int *val, char **arg, int *idx); -``` - -The {{i:`nng_opts_parse`}} function is a intended to facilitate parsing -{{i:command-line arguments}}. -This function exists largely to stand in for {{i:`getopt`}} from POSIX systems, -but it is available everywhere that _NNG_ is, and it includes -some capabilities missing from `getopt`. - -The function parses arguments from -`main`{{footnote: Parsing argument strings from other sources can be done as well, -although usually then _idx_ will be initialized to zero.}} -(using _argc_ and _argv_), -starting at the index referenced by _idx_. -(New invocations typically set the value pointed to by _idx_ to 1.) - -Options are parsed as specified by _spec_ (see [Option Specification](#option-specification).) -The value of the parsed option will be stored at the address indicated by -_val_, and the value of _idx_ will be incremented to reflect the next -option to parse. - -> [!TIP] -> For using this to parse command-line like strings that do not include -> the command name itself, set the value referenced by _idx_ to zero instead of one. - -If the option had an argument, a pointer to that is returned at the address -referenced by _arg_. - -This function should be called repeatedly, until it returns either -1 -(indicating the end of options is reached) or a non-zero error code is -returned. - -This function may return the following errors: - -- [`NNG_EAMBIGUOUS`]: Parsed option matches more than one specification. -- [`NNG_ENOARG`]: Option requires an argument, but one is not present. -- [`NNG_EINVAL`]: An invalid (unknown) argument is present. - -### Option Specification - -The calling program must first create an array of {{i:`nng_optspec`}} structures -describing the options to be supported. -This structure has the following members: - -- `o_name`: - - The long style name for the option, such as "verbose". - This will be parsed as a [long option](#long-options) on the command line when it is prefixed with two dashes. - It may be `NULL` if only a [short option](#short-options) is to be supported. - -- `o_short`: - - This is a single letter (at present only ASCII letters are supported). - These options appear as just a single letter, and are prefixed with a single dash on the command line. - The use of a slash in lieu of the dash is _not_ supported, in order to avoid confusion with path name arguments. - This value may be set to 0 if no [short option](#short-options) is needed. - -- `o_val`: - - This is a numeric value that is unique to this option. - This value is assigned by the application program, and must be non-zero for a valid option. - If this is zero, then it indicates the end of the specifications, and the - rest of this structure is ignored. - The value will be returned to the caller in _val_ by `nng_opts_parse` when - this option is parsed from the command line. - -- `o_arg`: - - This value should be set to `true` if the option should take an argument. - -### Long Options - -Long options are parsed from the _argv_ array, and are indicated when -the element being scanned starts with two dashes. -For example, the "verbose" option would be specified as `--verbose` on -the command line. -If a long option takes an argument, it can either immediately follow -the option as the next element in _argv_, or it can be appended to -the option, separated from the option by an equals sign (`=`) or a -colon (`:`). - -### Short Options - -Short options appear by themselves in an _argv_ element, prefixed by a dash (`-`). -If the short option takes an argument, it can either be appended in the -same element of _argv_, or may appear in the next _argv_ element. - -> [!NOTE] -> Option clustering, where multiple options can be crammed together in -> a single _argv_ element, is not supported by this function (yet). - -### Prefix Matching - -When using long options, the parser will match if it is equal to a prefix -of the `o_name` member of a option specification, provided that it do so -unambiguously (meaning it must not match any other option specification.) - -## Example - -The following program fragment demonstrates this function. - -```c - enum { OPT_LOGFILE, OPT_VERBOSE }; - char *logfile; // options to be set - bool verbose; - - static nng_optspec specs[] = { - { - .o_name = "logfile", - .o_short = 'D', - .o_val = OPT_LOGFILE, - .o_arg = true, - }, { - .o_name = "verbose", - .o_short = 'V', - .o_val = OPT_VERBOSE, - .o_arg = false, - }, { - .o_val = 0; // Terminate array - } - }; - - for (int idx = 1;;) { - int rv, opt; - char *arg; - rv = nng_opts_parse(argc, argv, specs, &opt, &arg, &idx); - if (rv != 0) { - break; - } - switch (opt) { - case OPT_LOGFILE: - logfile = arg; - break; - case OPT_VERBOSE: - verbose = true; - break; - } - } - if (rv != -1) { - printf("Options error: %s\n", nng_strerror(rv)); - exit(1); - } -``` - -{{#include ../xref.md}} -- cgit v1.2.3-70-g09d2