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.

1 files changed, 0 insertions, 165 deletions

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 `<nng/supplemental/util/options.h>`
-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}}