The Lean Mean C++ Option Parser
Public Member Functions
Parser Class Reference

Detailed Description

Checks argument vectors for validity and parses them into data structures that are easier to work with.

Example:
int main(int argc, char* argv[])
{
argc-=(argc>0); argv+=(argc>0); // skip program name argv[0] if present
option::Stats stats(usage, argc, argv);
option::Option options[stats.options_max], buffer[stats.buffer_max];
option::Parser parse(usage, argc, argv, options, buffer);
if (parse.error())
return 1;
if (options[HELP])
...

Definition at line 1055 of file optionparser.h.

Public Member Functions

 Parser ()
 Creates a new Parser. More...
 
 Parser (bool gnu, const Descriptor usage[], int argc, const char **argv, Option options[], Option buffer[], int min_abbr_len=0, bool single_minus_longopt=false, int bufmax=-1)
 Creates a new Parser and immediately parses the given argument vector. More...
 
 Parser (bool gnu, const Descriptor usage[], int argc, char **argv, Option options[], Option buffer[], int min_abbr_len=0, bool single_minus_longopt=false, int bufmax=-1)
 Parser(...) with non-const argv. More...
 
 Parser (const Descriptor usage[], int argc, const char **argv, Option options[], Option buffer[], int min_abbr_len=0, bool single_minus_longopt=false, int bufmax=-1)
 POSIX Parser(...) (gnu==false). More...
 
 Parser (const Descriptor usage[], int argc, char **argv, Option options[], Option buffer[], int min_abbr_len=0, bool single_minus_longopt=false, int bufmax=-1)
 POSIX Parser(...) (gnu==false) with non-const argv. More...
 
void parse (bool gnu, const Descriptor usage[], int argc, const char **argv, Option options[], Option buffer[], int min_abbr_len=0, bool single_minus_longopt=false, int bufmax=-1)
 Parses the given argument vector. More...
 
void parse (bool gnu, const Descriptor usage[], int argc, char **argv, Option options[], Option buffer[], int min_abbr_len=0, bool single_minus_longopt=false, int bufmax=-1)
 parse() with non-const argv. More...
 
void parse (const Descriptor usage[], int argc, const char **argv, Option options[], Option buffer[], int min_abbr_len=0, bool single_minus_longopt=false, int bufmax=-1)
 POSIX parse() (gnu==false). More...
 
void parse (const Descriptor usage[], int argc, char **argv, Option options[], Option buffer[], int min_abbr_len=0, bool single_minus_longopt=false, int bufmax=-1)
 POSIX parse() (gnu==false) with non-const argv. More...
 
int optionsCount ()
 Returns the number of valid Option objects in buffer[]. More...
 
int nonOptionsCount ()
 Returns the number of non-option arguments that remained at the end of the most recent parse() that actually encountered non-option arguments. More...
 
const char ** nonOptions ()
 Returns a pointer to an array of non-option arguments (only valid if nonOptionsCount() >0 ). More...
 
const char * nonOption (int i)
 Returns nonOptions()[i] (without checking if i is in range!). More...
 
bool error ()
 Returns true if an unrecoverable error occurred while parsing options. More...
 

Constructor & Destructor Documentation

Parser ( )

Creates a new Parser.

Definition at line 1066 of file optionparser.h.

Parser ( bool  gnu,
const Descriptor  usage[],
int  argc,
const char **  argv,
Option  options[],
Option  buffer[],
int  min_abbr_len = 0,
bool  single_minus_longopt = false,
int  bufmax = -1 
)

Creates a new Parser and immediately parses the given argument vector.

Parameters
gnuif true, parse() will not stop at the first non-option argument. Instead it will reorder arguments so that all non-options are at the end. This is the default behaviour of GNU getopt() but is not conforming to POSIX.
Note, that once the argument vector has been reordered, the gnu flag will have no further effect on this argument vector. So it is enough to pass gnu==true when creating Stats.
usageArray of Descriptor objects that describe the options to support. The last entry of this array must have 0 in all fields.
argcThe number of elements from argv that are to be parsed. If you pass -1, the number will be determined automatically. In that case the argv list must end with a NULL pointer.
argvThe arguments to be parsed. If you pass -1 as argc the last pointer in the argv list must be NULL to mark the end.
optionsEach entry is the first element of a linked list of Options. Each new option that is parsed will be appended to the list specified by that Option's Descriptor::index. If an entry is not yet used (i.e. the Option is invalid), it will be replaced rather than appended to.
The minimum length of this array is the greatest Descriptor::index value that occurs in usage PLUS ONE.
bufferEach argument that is successfully parsed (including unknown arguments, if they have a Descriptor whose CheckArg does not return ARG_ILLEGAL) will be stored in this array. parse() scans the array for the first invalid entry and begins writing at that index. You can pass bufmax to limit the number of options stored.
min_abbr_lenPassing a value min_abbr_len > 0 enables abbreviated long options. The parser will match a prefix of a long option as if it was the full long option (e.g. –foob=10 will be interpreted as if it was –foobar=10 ), as long as the prefix has at least min_abbr_len characters (not counting the ) and is unambiguous.
Be careful if combining min_abbr_len=1 with single_minus_longopt=true because the ambiguity check does not consider short options and abbreviated single minus long options will take precedence over short options.
single_minus_longoptPassing true for this option allows long options to begin with a single minus. The double minus form will still be recognized. Note that single minus long options take precedence over short options and short option groups. E.g. -file would be interpreted as –file and not as -f -i -l -e (assuming a long option named "file" exists).
bufmaxThe greatest index in the buffer[] array that parse() will write to is bufmax-1. If there are more options, they will be processed (in particular their CheckArg will be called) but not stored.
If you used Stats::buffer_max to dimension this array, you can pass -1 (or not pass bufmax at all) which tells parse() that the buffer is "large enough".
Attention
Remember that options and buffer store Option objects, not pointers. Therefore it is not possible for the same object to be in both arrays. For those options that are found in both buffer[] and options[] the respective objects are independent copies. And only the objects in options[] are properly linked via Option::next() and Option::prev(). You can iterate over buffer[] to process all options in the order they appear in the argument vector, but if you want access to the other Options with the same Descriptor::index, then you must access the linked list via options[]. You can get the linked list in options from a buffer object via something like options[buffer[i].index()].

Definition at line 1075 of file optionparser.h.

Parser ( bool  gnu,
const Descriptor  usage[],
int  argc,
char **  argv,
Option  options[],
Option  buffer[],
int  min_abbr_len = 0,
bool  single_minus_longopt = false,
int  bufmax = -1 
)

Parser(...) with non-const argv.

Definition at line 1083 of file optionparser.h.

Parser ( const Descriptor  usage[],
int  argc,
const char **  argv,
Option  options[],
Option  buffer[],
int  min_abbr_len = 0,
bool  single_minus_longopt = false,
int  bufmax = -1 
)

POSIX Parser(...) (gnu==false).

Definition at line 1091 of file optionparser.h.

Parser ( const Descriptor  usage[],
int  argc,
char **  argv,
Option  options[],
Option  buffer[],
int  min_abbr_len = 0,
bool  single_minus_longopt = false,
int  bufmax = -1 
)

POSIX Parser(...) (gnu==false) with non-const argv.

Definition at line 1099 of file optionparser.h.

Member Function Documentation

bool error ( )

Returns true if an unrecoverable error occurred while parsing options.

An illegal argument to an option (i.e. CheckArg returns ARG_ILLEGAL) is an unrecoverable error that aborts the parse. Unknown options are only an error if their CheckArg function returns ARG_ILLEGAL. Otherwise they are collected. In that case if you want to exit the program if either an illegal argument or an unknown option has been passed, use code like this

if (parser.error() || options[UNKNOWN])
exit(1);

Definition at line 1258 of file optionparser.h.

const char* nonOption ( int  i)

Returns nonOptions()[i] (without checking if i is in range!).

Definition at line 1238 of file optionparser.h.

const char** nonOptions ( )

Returns a pointer to an array of non-option arguments (only valid if nonOptionsCount() >0 ).

Note
  • parse() does not copy arguments, so this pointer points into the actual argument vector as passed to parse().
  • As explained at nonOptionsCount() this pointer is only changed by parse() calls that actually encounter non-option arguments. A parse() call that encounters only options, will not change nonOptions().

Definition at line 1230 of file optionparser.h.

int nonOptionsCount ( )

Returns the number of non-option arguments that remained at the end of the most recent parse() that actually encountered non-option arguments.

Note
A parse() that does not encounter non-option arguments will leave this value as well as nonOptions() undisturbed. This means you can feed the Parser a default argument vector that contains non-option arguments (e.g. a default filename). Then you feed it the actual arguments from the user. If the user has supplied at least one non-option argument, all of the non-option arguments from the default disappear and are replaced by the user's non-option arguments. However, if the user does not supply any non-option arguments the defaults will still be in effect.

Definition at line 1214 of file optionparser.h.

int optionsCount ( )

Returns the number of valid Option objects in buffer[].

Note
  • The returned value always reflects the number of Options in the buffer[] array used for the most recent call to parse().
  • The count (and the buffer[]) includes unknown options if they are collected (see Descriptor::longopt).

Definition at line 1195 of file optionparser.h.

void parse ( bool  gnu,
const Descriptor  usage[],
int  argc,
const char **  argv,
Option  options[],
Option  buffer[],
int  min_abbr_len = 0,
bool  single_minus_longopt = false,
int  bufmax = -1 
)

Parses the given argument vector.

Parameters
gnuif true, parse() will not stop at the first non-option argument. Instead it will reorder arguments so that all non-options are at the end. This is the default behaviour of GNU getopt() but is not conforming to POSIX.
Note, that once the argument vector has been reordered, the gnu flag will have no further effect on this argument vector. So it is enough to pass gnu==true when creating Stats.
usageArray of Descriptor objects that describe the options to support. The last entry of this array must have 0 in all fields.
argcThe number of elements from argv that are to be parsed. If you pass -1, the number will be determined automatically. In that case the argv list must end with a NULL pointer.
argvThe arguments to be parsed. If you pass -1 as argc the last pointer in the argv list must be NULL to mark the end.
optionsEach entry is the first element of a linked list of Options. Each new option that is parsed will be appended to the list specified by that Option's Descriptor::index. If an entry is not yet used (i.e. the Option is invalid), it will be replaced rather than appended to.
The minimum length of this array is the greatest Descriptor::index value that occurs in usage PLUS ONE.
bufferEach argument that is successfully parsed (including unknown arguments, if they have a Descriptor whose CheckArg does not return ARG_ILLEGAL) will be stored in this array. parse() scans the array for the first invalid entry and begins writing at that index. You can pass bufmax to limit the number of options stored.
min_abbr_lenPassing a value min_abbr_len > 0 enables abbreviated long options. The parser will match a prefix of a long option as if it was the full long option (e.g. –foob=10 will be interpreted as if it was –foobar=10 ), as long as the prefix has at least min_abbr_len characters (not counting the ) and is unambiguous.
Be careful if combining min_abbr_len=1 with single_minus_longopt=true because the ambiguity check does not consider short options and abbreviated single minus long options will take precedence over short options.
single_minus_longoptPassing true for this option allows long options to begin with a single minus. The double minus form will still be recognized. Note that single minus long options take precedence over short options and short option groups. E.g. -file would be interpreted as –file and not as -f -i -l -e (assuming a long option named "file" exists).
bufmaxThe greatest index in the buffer[] array that parse() will write to is bufmax-1. If there are more options, they will be processed (in particular their CheckArg will be called) but not stored.
If you used Stats::buffer_max to dimension this array, you can pass -1 (or not pass bufmax at all) which tells parse() that the buffer is "large enough".
Attention
Remember that options and buffer store Option objects, not pointers. Therefore it is not possible for the same object to be in both arrays. For those options that are found in both buffer[] and options[] the respective objects are independent copies. And only the objects in options[] are properly linked via Option::next() and Option::prev(). You can iterate over buffer[] to process all options in the order they appear in the argument vector, but if you want access to the other Options with the same Descriptor::index, then you must access the linked list via options[]. You can get the linked list in options from a buffer object via something like options[buffer[i].index()].

Definition at line 1490 of file optionparser.h.

void parse ( bool  gnu,
const Descriptor  usage[],
int  argc,
char **  argv,
Option  options[],
Option  buffer[],
int  min_abbr_len = 0,
bool  single_minus_longopt = false,
int  bufmax = -1 
)

parse() with non-const argv.

Definition at line 1166 of file optionparser.h.

void parse ( const Descriptor  usage[],
int  argc,
const char **  argv,
Option  options[],
Option  buffer[],
int  min_abbr_len = 0,
bool  single_minus_longopt = false,
int  bufmax = -1 
)

POSIX parse() (gnu==false).

Definition at line 1173 of file optionparser.h.

void parse ( const Descriptor  usage[],
int  argc,
char **  argv,
Option  options[],
Option  buffer[],
int  min_abbr_len = 0,
bool  single_minus_longopt = false,
int  bufmax = -1 
)

POSIX parse() (gnu==false) with non-const argv.

Definition at line 1180 of file optionparser.h.


The documentation for this class was generated from the following file: