i386/ucla/src/lab5/inc/args.h

   1 #ifndef JOS_INC_ARGS_H
   2 #define JOS_INC_ARGS_H
   3
   4 struct Argstate;
   5
   6 // JOS command-line parsing functions.
   7
   8 // Initializes the Argstate buffer from argc and argv.
   9 // (Note: it is safe to use a 'const char **' for argv.)
  10 void argstart(int *argc, char **argv, struct Argstate *args);
  11
  12 // Returns the next flag in the argument list,
  13 // or -1 if there are no more flags.
  14 //
  15 // Flags stop at a non-flag (anything that doesn't start with '-'),
  16 // at the end of the argument list, before "-", or after "--",
  17 // whichever comes first.  Any "--" argument is not returned.
  18 //
  19 // Consumes arguments from the argc/argv array passed in to argstart.
  20 // If you argstart with an argc/argv array of ["sh", "-i", "foo"],
  21 // the first call to argnext will return 'i' and change the array to
  22 // ["sh", "foo"].  Thus, when argnext returns -1, the argc/argv array
  23 // contains just the non-flag arguments.
  24 int argnext(struct Argstate *);
  25
  26 // Returns the next value for the current flag, or 0 if it has no value.
  27 // For example, given an argument list ["-fval1", "val2", "val3"],
  28 // a call to argnext() will return 'f', after which repeated calls to
  29 // argnextvalue will return "val1", "val2", and "val3".
  30 // Consumes arguments from the argc/argv array.
  31 char *argnextvalue(struct Argstate *);
  32
  33 // Returns the current flag's value, or 0 if it has no value.
  34 // Behaves like argnextvalue, except that repeated calls to argvalue will
  35 // return the same value.
  36 char *argvalue(struct Argstate *);
  37
  38 // Used by panic() to print the program name.
  39 extern const char *argv0;
  40
  41 // Example:
  42 //
  43 //      #include <inc/lib.h>
  44 //
  45 //      void
  46 //      umain(int argc, char **argv)
  47 //      {
  48 //              int i;
  49 //              struct Argstate args;
  50 //
  51 //              argstart(&argc, argv, &args);
  52 //              while ((i = argnext(&args)) >= 0)
  53 //                      switch (i) {
  54 //                      case 'r':
  55 //                      case 'x':
  56 //                              cprintf("'-%c' flag\n", i);
  57 //                              break;
  58 //                      case 'f':
  59 //                              cprintf("'-f %s' flag\n", argvalue(&args));
  60 //                              break;
  61 //                      default:
  62 //                              cprintf("unknown flag\n");
  63 //                      }
  64 //
  65 //              for (i = 1; i < argc; i++)
  66 //                      cprintf("argument '%s'\n", argv[i]);
  67 //      }
  68 //
  69 // If this program is run with the arguments
  70 // ["-rx", "-f", "foo", "--", "-r", "duh"]
  71 // it will print out
  72 //      '-r' flag
  73 //      '-x' flag
  74 //      '-f foo' flag
  75 //      argument '-r'
  76 //      argument 'duh'
  77
  78 struct Argstate {
  79         int *argc;
  80         const char **argv;
  81         const char *curarg;
  82         const char *argvalue;
  83 };
  84
  85 #endif