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(libc.info)Argp Parsing State

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Argp Parsing State
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   The third argument to argp parser functions (Note: Argp Parser
Functions) is a pointer to a `struct argp_state', which contains
information about the state of the option parsing.

 - Data Type: struct argp_state
     This structure has the following fields, which may be modified as
     noted:

    `const struct argp *const root_argp'
          The top level argp parser being parsed.  Note that this is
          often _not_ the same `struct argp' passed into `argp_parse' by
          the invoking program.  Note: Argp.  It is an internal argp
          parser that contains options implemented by `argp_parse'
          itself, such as `--help'.

    `int argc'
    `char **argv'
          The argument vector being parsed.  This may be modified.

    `int next'
          The index in `argv' of the next argument to be parsed.  This
          may be modified.

          One way to consume all remaining arguments in the input is to
          set `STATE->next = STATE->argc', perhaps after recording the
          value of the `next' field to find the consumed arguments.  The
          current option can be re-parsed immediately by decrementing
          this field, then modifying `STATE->argv[STATE->next]' to
          reflect the option that should be reexamined.

    `unsigned flags'
          The flags supplied to `argp_parse'.  These may be modified,
          although some flags may only take effect when `argp_parse' is
          first invoked.  Note: Argp Flags.

    `unsigned arg_num'
          While calling a parsing function with the KEY argument
          `ARGP_KEY_ARG', this represents the number of the current arg,
          starting at 0.  It is incremented after each `ARGP_KEY_ARG'
          call returns.  At all other times, this is the number of
          `ARGP_KEY_ARG' arguments that have been processed.

    `int quoted'
          If non-zero, the index in `argv' of the first argument
          following a special `--' argument.  This prevents anything
          that follows from being interpreted as an option.  It is only
          set after argument parsing has proceeded past this point.

    `void *input'
          An arbitrary pointer passed in from the caller of
          `argp_parse', in the INPUT argument.

    `void **child_inputs'
          These are values that will be passed to child parsers.  This
          vector will be the same length as the number of children in
          the current parser.  Each child parser will be given the
          value of `STATE->child_inputs[I]' as _its_ `STATE->input'
          field, where I is the index of the child in the this parser's
          `children' field.  Note: Argp Children.

    `void *hook'
          For the parser function's use.  Initialized to 0, but
          otherwise ignored by argp.

    `char *name'
          The name used when printing messages.  This is initialized to
          `argv[0]', or `program_invocation_name' if `argv[0]' is
          unavailable.

    `FILE *err_stream'
    `FILE *out_stream'
          The stdio streams used when argp prints.  Error messages are
          printed to `err_stream', all other output, such as `--help'
          output) to `out_stream'.  These are initialized to `stderr'
          and `stdout' respectively.  Note: Standard Streams.

    `void *pstate'
          Private, for use by the argp implementation.