Entry

TSE: Parse: Parameter: Command line: MSDOS: How to possibly parse the command line?

May 15th, 2005 01:31
Knud van Eeden,

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--- Knud van Eeden --- 15 May 2021 - 01:29 pm ------------------------
TSE: Parse: Parameter: Command line: MSDOS: How to possibly parse the 
command line?
===
e.g.
 g32.exe -ic:\temp\test.txt
---
e.g.
 e32.exe -lc:\temp\my.mac
---
e.g.
 c:\tse\g32.exe -i"c:\temp\ -itisatestdirectory\"
---
e.g.
 c:\tse\g32.exe -i"c:\temp\ -itisatestdirectory\" -e"c:\my-macro-
example.mac"
---
e.g.
 c:\tse\g32.exe -i"c:\temp\ -itisatestdirectory\" -e"c:\my-macro-
example.mac" -lc:\my.mac
===
In words:
1. The command line is
   1. an executable name,
      followed by zero or more parameters,
      followed by an end of line
      1. A parameter is
         one or more spaces,
         followed by the character '-',
         followed by a character,
         followed by zero or one filename
         1. A filename
            starts with a double quote,
            followed by some characters
            (possibly also spaces and dashes),
            finished by a double quote
         -- or --
         1. A filename contains some characters, but no spaces
===
Backus Naur Form:
---
command line =
                      +--------<--------+
                      |                 |
->-[executablename]->-+->-[parameter]->-+->-[end of line]
                      |                 |
                      +-------->--------+
---
parameter =
    +-----<-----+
    |           |
 ->-+-(space)->-+-(-)->-[character]->-+->-[filename]->-+->-
    |           |                     |                |
    +-----------+                     +-------->-------+
---
filename =
 ->-+->-(")->-[some characters possibly also spaces]->-(")->-+-->
    |                                                        |
    +->-------[some characters, but no spaces]->-------+-->--+
===
To parse:
1. start parsing from begin of the line, and from left to right (and
   not somewhere in the middle thus)
   1. if you while parsing from left to right:
       1. first find a space with a '-' followed by a character after
          it (e.g. ' -i'), it must be a parameter.
          1. Then after this parameter comes possibly a filename, which
             you then parse as usual
              1. If you find a starting double quote, parse further
                 until you find the closing double quote (it might also
                 have a '-' with a character after it (e.g. ' -i') in
                 it, if the filename has quotes around it)
              1. If you do not find a double quote, parse it as usual
                 for a filename
===
To parse: program
---
if not [executablename]
 exit
endif
if [end of line]
 exit
endif
// read parameters
while ( current character == (space) )
 while (space)
  read
 endwhile
 if (-)
  read
 else
  exit
 endif
 if [character]
  read
 else
  error
  exit
 endif
 if [filename]
  if (double quote)
   read until finishing (double quote)
  else
   read until space or end of line
  endif
 endif
endwhile
if not [end of line]
 error
 exit
endif
===
Note:
About spaces:
You possibly will have to write this parsing routine
yourself.
If you are relying on the argv[] array in C or C++, or ParamStr() in
Delphi, or other command line parameter arrays in the different
programming languages, which see by design the spaces as parameter
separators, that will thus not work if your filenames contain spaces
(as it will then break the filenames in parts, at the position of this
spaces)
---
---
Internet: see also:
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