Category : BASIC Source Code
Archive   : QBSUBS10.ZIP
Filename : PARSE.SUB

' PARSE.ASC -- MSDOS QuickBASIC subroutine parses COMMAND$ 25 June 86
' by David L. Poskie (608) 274-9560
' 7118 Raymond Rd. Madison, WI 53719
' Please run any suggestions, corrections, additions, or changes by me.
' I can be messaged on all the major Madison, WI RBBS's.

'| >>> OMNI.SUB and PARSE.SUB must be $Included in main program.
'| DIMensioning MUST be done in the main program; e.g.:
'| NumMax = 2 : DIM Cmd$(NumMax)
'| This would allow 2 commands (we ignore Cmd$(0) here).
'|
'| Function: Parse the command line tail, getting as many commands as exist
'| (up to the maximum set by the Cmd$(NumMax) dimension statement
'| in the main program).
'| Requires commands be separated by one or more
'| definable characters, (I use spaces here).
'| Input: NumMax = maximum number of commands this subroutine will parse
'| COMMAND$ = DOS command line function
'| Output: Num = the number of commands parsed.
'| Cmd$(1) to Cmd$(NumMax) = the separated command strings.
'| Other Vars: Text$ = internal work string
'| IsSep = flags the presence of a separator in Text$
'| Sep$ = one or more legal separators

Parse:
' We'll work with Text$ because COMMAND$ can't be altered
Text$ = COMMAND$
' Sep$ is the legal command separator (change as you desire)
Sep$ = " "
' Num = the number of command/s in the command line tail.
Num = 0
' Bail out on empty command line
IF Text$ = "" _
THEN GOTO ParseExit
' Bail out on non-alpha first character in command line
IF ASC(Text$) < 65 _
OR ASC(Text$) > 90 _
THEN GOTO ParseError
' We start filling Cmd$(Num)
' Look for from 1 to NumMax commands to put in Cmd$(Num)
Num = 1
ParseLoop:
' IsSep flags the occurrance & location of the first separator in Text$
IsSep = INSTR(Text$ , Sep$)
' If no separator, there is only this command left
IF IsSep = False _
THEN Cmd$(Num) = Text$ : _
GOTO ParseExit
' There is a separator, so get the command
IF Num =< NumMax _
THEN Cmd$(Num) = LEFT$(Text$ , IsSep - 1)
' If at our limit -- time to go
IF Num > NumMax _
THEN GOTO ParseExit
' Adjust Text$
Text$ = RIGHT$(Text$ , LEN(Text$) - IsSep)
' Adjust the count
Num = Num + 1
' Go filter any leading spaces or TABs in Text$
WHILE ASC(Text$) = 9 _
OR ASC(Text$) = 32
Text$ = RIGHT$(Text$ , LEN(Text$) - 1)
WEND
' Back for another command
GOTO ParseLoop
ParseError:
Text$ = "Non-alpha command . . ."
GOSUB Center
BEEP
ParseExit:
RETURN
' >>>>> Physical EOF PARSE.SUB 25 June 86