Parse-O-Matic: Flow Control Script Commands for Parsing Data Files

Overview

Parse-O-Matic's flow control commands (such as If,Begin,End,Again,Stop)let you control the order in which the lines of your script are executed.You can,for example,execute a block of commands only under certain circumstances,or cause a group of commands to be executed repeatedly (“looping ”).You can also define generalized procedures to save you having to duplicate code.

Again

Format	Again [v1 k2 v3 ]
Examples	See the Begin command
Purpose	Causes a Begin block to repeat if the comparison is true (or if no comparison is specified)
Parameters	v1 -Value to be compared k2 -Comparator v3 -Value to compare to v1
Restrictions	You cannot combine an Again command with an If command.

Begin

Format	Begin [v1 k2 v3 ]
Examples	Begin MyVar ='XYZ';Execute block if MyVar equals 'XYZ'
Purpose	Marks the start of a conditional block of script code
Parameters	v1 -Value to be compared k2 -Comparator v3 -Value to compare to v1
Defaults	If no comparison is specified,the block always begins.In such case,it makes no sense to have an Else command,and it almost invariably means that the block will end with an Again command.
Restrictions	You cannot combine a Begin command with an If command.
Similar Cmds	If
Notes	Comparisons are not case-sensitive,so 'CAT'='Cat'(unless you have altered the CompareCtrl setting). The Begin command does not set the $Success variable! Begin blocks can be nested up to 25 levels deep.

Here is an example of the Begin command,used with Else and End:

Begin MyVar ='Cat'
OutEnd 'The animal is feline' OutEnd 'In fact,it is a cat'	;Executed if MyVar ='Cat' ;Executed if MyVar ='Cat'
Else
OutEnd 'The animal is not feline'	;Executed if MyVar is not 'Cat'
End

Note the use of indentation.Indentation of the conditional code blocks is not mandatory,but it does make a complicated script much easier to understand.This is particularly important if a Begin block contains other Begin blocks:

Begin CustCode [ 1 3 ] ='USA'

OutEnd 'The customer is in the USA'
Begin CustCode [ 4 5 ] ='NY'

OutEnd 'The customer is in New York'

End

Begin CustCode [ 4 5 ] ='TX'

OutEnd 'The customer is in Texas'

End

Without the indentation,the logic of the code above would be hard to follow.

Here is an example of the Begin command used in a loop:

Counter =0
Begin

Counter =Counter+
OutEnd 'The counter equals 'Counter

Again Counter #<10

This would output the numbers from 1 to 10.You could also do it this way:

Counter =0
Begin Counter #<10

Counter =Counter+
OutEnd 'The counter equals 'Counter

Again

This would output the numbers from 1 to 10.

If you wish,you can put comparisons on both the Begin and Again.Both tests are repeated on every iteration of the loop.

Break

Format	Break
Examples	If CustNum =MaxCustNum Break
Purpose	Breaks out of the current Begin/Again block,carrying on execution at the line following the next Again command
Similar Cmds	Continue

Call

Format	Call v1 [v2 v3 v4...]
Examples	Call MyProcedure 'Hello!';Pass 'Hello!'to MyProcedure
Purpose	Invoke a generalized section of script code
Parameters	v1 -The name of the Procedure;doubles as a variable for passing information to and receiving results back from the Procedure v2 -Value (any number of values can be appended)
Defaults	If v2 is not specified,the procedure variable v1 is assigned a null value.
Restrictions	Calls from procedures into other procedures,which in turn call other procedures (and so on),can nest up to 50 levels deep.

When you Call a procedure,execution of the script jumps to the first line of the procedure and continues until the corresponding End statement.The name of the procedure is also the variable name containing any parameters passed in v2,v3 and so on (the values are concatenated).Here is a sample script:

Call OutWithExclaim 'Hello,''world'	;Call the procedure
OutEnd 'Glad you could join us!'	;This line is run after the Call
Stop	;Stop running script lines
Procedure OutWithExclaim	;Start of the procedure
OutWithExclaim =OutWithExclaim '!'	;Add an exclamation point
OutEnd OutWithExclaim	;Output
End	;Return to the line after the Call

This would output the string 'Hello,world!'then return to the line following the Call command.

Continue

Format	Continue
Examples	If Status ='Ignore'Continue
Purpose	Jumps ahead to the Again of the current Begin/Again block
Similar Cmds	Break

Done

Format	Done
Examples	Skips the rest of the script (for the current record)
Purpose	Stop,NextFile,NextStep
Similar Cmds	The Done command is usually used with the If command, or at the end of a Begin/End block.

Here is an example of the Done command:

If EmployeeNum <>1234 Done

In this case,we are checking to see if the variable EmployeeNum is equal to 1234.If it is not,we skip the remainder of the current processing step.

Else

Format	Else
Examples	See the Begin command
Purpose	Defines the start of the conditional code block that is executed if the Begin comparison is false.
Restrictions	You cannot combine an Else command with an If command.

End

Format	End
Examples	See the Begin command
Purpose	Marks the end of a Begin block
Restrictions	You cannot combine an End command with an If command.

Exit

Format	Exit
Purpose	Immediately returns from a Procedure
Restrictions	You cannot combine an End command with an If command.

The Exit command is typically used in conjunction with a comparison.You do not need to include an Exit command in every Procedure;it is used to skip the rest of the procedure if some condition is met.For example:

Procedure AdjustPhoneNumber
TrimChar PhoneNumber 'A ' Change PhoneNumber '/''-' Change PhoneNumber '.''-' AreaCode =PhoneNumber [1 3 ] If AreaCode ='416'Exit If AreaCode ='905'Exit PhoneNumber ='1-'PhoneNumber	;Remove spaces ;Tidy up format ;Tidy up format
End

In this example,the procedure puts '1-'in front of a phone number unless it starts with 416 or 905.

Format	If v1 k2 v3 c4
Examples	If CustCode ='AB12'OutEnd 'Mary Smith' If CustCode ='CD34'CustAddr ='1234 Happy Lane'
Purpose	Conditionally performs a command
Parameters	v1 -Value to be compared k2 -Comparator v3 -Value to compare to v1 c4 -Command
Restrictions	The If command may not be combined with a command that defines the start of a code block,such as Begin or FileInit.
Similar Cmds	Begin,Again
Notes	The comparison is case-insensitive,so 'CAT'='cat'unless you have altered the CompareCtrl setting. The If command does not set the $Success variable!

In deference to the ingrained training of seasoned programmers,you may use the word “then ” after the comparison.Thus,the following command will be accepted:

If x >y then z ='Hello'

This usage is non-standard,however,and is not recommended.The scripting engine treats the “then ” as a variable,but ignores it in this context.Thus,you should never use a variable named “Then ”.

The If command does not have an “Else ” option as in most programming languages..To execute a command when the If condition is false,use the Otherwise command.Alternatively,you can use the Begin command with an Else section.

Otherwise

Format	Otherwise c1
Examples	If Animal ='Cat'Type ='Feline';The initial If command Otherwise Type ='Non-feline';Action taken if false
Purpose	Executes an alternative command when the If comparison is false
Parameters	c1 -Command
Restrictions	The Otherwise command must follow immediately after an If. The Otherwise command may not be combined with a command that defines the start of a code block,such as Begin or FileInit.
Similar Cmds	Else

Procedure

Format	Procedure v1
Examples	Procedure MyCode
Purpose	Defines the start of a generalized section of script code,which is terminated with the End command
Parameters	v1 -The name of the Procedure (must be a simple variable)
Restrictions	Recursive procedures (i.e.procedures that call themselves)are not formally supported and their use is not recommended.
Notes	See the Call command for additional details about procedures.

As the script is being run,any Procedure sections are ignored when encountered;they are only executed
when explicitly invoked by Call.Procedures can go anywhere except within conditional blocks such as
Begin/End,FileInit/End and so on.Procedures are usually placed together at the end of the script.

Stop

Format	Stop [v1 ]
Examples	If CustNum [1 ] ='X'Stop 'Invalid customer number'
Purpose	Terminates further processing
Parameters	v1 -Optional pop-up message
Similar Cmds	Done,NextStep
Notes	If v1 is included,a pop-up message is displayed.In such case, the Stop is considered an “abnormal ” end of processing and the script-enabled application should proceed accordingly.

(This page is part of the online user manual for Parse-O-Matic. Parse-O-Matic is a programmable parsing tool that can extract, manipulate, convert or mine existing data sources and turn them into importable data. For more information on Parse-O-Matic products and conversion services, please visit www.ParseOMatic.com)