Scripting Language Syntax

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Both NairnFEAMPM and NairnFEAMPMViz have built-in scripting languages for programmatically setting up calculations. This section describes language syntax and all generic commands for programming control.

Language Syntax

This sections describes the syntax of command lines and gives the definitions of variables and expressions.

Conditional Commands

The if, ifStr, ifDef, and ifNDef commands are used to define conditional blocks. The if command is for numeric comparisons; the ifStr commands is for string comparisons; the ifDef and ifNDef commands are to check if variables have been defined. The format of a conditional block is: 

if (num1) (op) (num2)
  (block of commands if numeric comparison is true)
    .
else ifStr (string1) (op) (string2)
  (block of commands if string comparison is true)
    .
else if (num1)
  (block of commands if (num1) is not zero)
    .
else ifStr (string1)
  (block of commands if (string1) is not empty)
    .
else ifDef #varName
  (block of commands if #varNam is a defined variable)
    .
else ifNDef #varName
  (block of commands if #varNam is not a defined variable)
    .
else
  (block of commands if no prior condition is true)<br>
endif

where there can be any number of conditionals and each can be of any type. If either arguments to an if conditional are strings instead of numbers, that conditional will automatically be converted to an ifStr command. In other words, there is no need to use ifStr unless you explicit want to compare two strings as strings when they happen to also be valid numbers. The arguments to ifDef and ifNDef must be a single variable name.

Numeric Comparisons

Numerical conditionals compare (num1) to (num2) with the following comparison operators for (op):

  • = or == or ' is ': true if (num1) is equal to (num2).
  • != or <> : true if (num1) is not equal to (num2).
  • > : true if (num1) is greater than (num2).
  • >= : true if (num1) is greater than or equal to (num2).
  • < :true if (num1) is less than (num2).
  • <= : true if (num1) is less than or equal to (num2).

String Comparisons

String conditionals are nearly the same except ordering is alphabetical order instead of numerical order. Furthermore the two "equals" operators provide case-insensitive or case-sensitive comparisons as follows:

  • = or ' is ': true if (string1) is equal to (string2) by case-insensitive comparison.
  • == : true if (string1) is equal to (string2) by case-sensitive comparison (i.e., two equals signs means more equal than one equals sign).

Notes on Conditionals

  1. Some string functions can be used to implement other types of useful string comparisons. For example:
    • if offset(s1\string)>0 - is true if the string contains the string s1.
    • if chars("\"&length(s1)&"\string")=s1 - is true if string starts with the string s1 (case insensitive, use == to make it case sensitive).
    • if chars((length(string)-length(s1)+1)&"\string")=s1 - is true if string ends with the string s1 (case insensitive, use == to make it case sensitive).
  2. When a numeric conditional has only a single number and no comparison operator (such as if (num1)), the conditional is true if the number is not equal to zero. If the number is not zero, the conditional is false.
  3. When a string conditional has only a single string and no comparison operator (such as ifStr (string1)), the conditional is true if the string is not an empty string. If the string has text, the conditional is false.

Repeat Commands

The Repeat command can be used to set up loops in the commands. The format for repeat loops, which may be nested, is: 

Repeat "#x",start,end,<step>
  (commands in the loop)
    ...
  break
    ...
  Repeat "#y",start,end,<step>
    (commands in nested loop)
      ...
    continue
      ...
    Repeat
      (commands in nested continuous loop)
        ...
      breakAll
        ...
    EndRepeat
  EndRepeat
EndRepeat

where

  • Repeat "#x",min,max,step
    This command sets up a repeat loop. The repeat variable appears first and it must be quoted to prevent evaluation as an expression. The subsequent three arguments give the starting and ending values for the loop and the step size to increment the value each pass through the loop. If the step size is not included, it is set to 1. Negative step sizes are allowed. A loop may have zero passes if start is greater than end (for positive step size) or less then end (for negative step size).
  • A Repeat with no variables will loop forever. It will cause an endless loop unless some condition within the loop forces a break.
  • A break can be used in any loop. It will exit the current loop. If there are nested loops, control will enter the next higher loop.
  • A breakAll can be used in any loop. It will exit all current loops and pass control to after the last EndRepeat command.
  • A continue command will increment the current loop variable and go back to the start of that loop. If the loop is done, it will exit.

Notes on Repeat Commands

  1. You cannot permanently change the loop variable during a loop. If you change it, it will be reset to the next loop value at the start of the next pass through the loop. For example: 
    Repeat "#x",1,5
  Write #x
  #x+=10
EndRepeat
    will write 1,2,3,4,5 on successive lines even though #x</t> was changed in the loop. Each pass through the loop resets #x to the next loop value.

Subroutine Commands

The commands can include subroutines. All subroutines must be defined at the start of the commands. The commands that get executed and will call the subroutines must start with the first command after the last subroutine definition.

A subroutine, which can be called with a GoSub command, is defined as follows: 

Sub subname #arg1,#arg2,...,#argn
  (subroutine commands)
    .
    .
    .
  return
    .
    .
    .
EndSub

where

  • subname is the name of the subroutine. The names of all subroutines must be unique.
  • #arg1,#arg2,...,#argn are any number of subroutine arguments. The name of each argument must be a valid variable name and must not be in quotes.
  • The subroutine ends with the EndSub command and execution will return to the line after the GoSub command that called the subroutine.
  • The return command can be used to exit a subroutine at any time before the its end.

Calling Subroutines

The GoSub command is used to call subroutines. The calling format is 

GoSub subname #1,#2,...#n

where

  • subname is the name of the subroutine.
  • #1,#2,...,#n are any expressions. The total number of expressions must exactly match the number of arguments in the subroutine definition. The variables in the subroutine definition will be set equal to the values passed in the GoSub command.

Notes on Subroutines

  1. All variables are global variables. Thus subroutines can use variables set in the main commands and the main commands can access variables defined in the subroutines including subroutine arguments. If a subroutine argument matches a variable from the main commands, calling the subroutine will overwrite that value.
  2. Subroutines can be nested which means subroutines can call any other subroutines with GoSub commands.

Output and Debugging Commands

These commands print output to the lower field in the input commands window or stop an analysis in progress. They are normally for debugging calculation commands.

  • <a href="clear.html">Clear</a>: Clear the output area.
  • <a href="dump.html">Dump</a>: Write all arguments to output area for debugging.
  • <a href="message.html">Message</a>: Write arguments to the message panel.
  • <a href="write.html">Write</a>: Write arguments to output area.
  • <a href="stop.html">Stop</a>: Stop the analysis.

Differences in the NairnFEAMPMViz Scripting Language

The scripting language in NairnFEAMPMViz is based on the corresponding scripting commands in the Mac application NairnFEAMPM, but it is not as fully developed. The key difference in NairnFEAMPMViz are:

  1. String variables are required to end in a $, while in NairnFEAMPM, that is not required, but is allowed.
  2. The main command on each line must be separeted from arguments by a space and arguments must be delimited by commands. In NairnFEAMPM commands and arguments can be delimited by commas, spaces, or tabs.
  3. Variables can begin in a letter or a #. In NairnFEAMPM, they must all begin in #.
  4. String expression can only combine quoted text and variables with the & operator. In NairnFEAMPM, numeric expressions can be embedded in string expressions by grouping them in parentheses, but that is not allowed in NairnFEAMPMViz.
  5. Array variables (using [] after the variable name) is not yet developed for NairnFEAMPMViz.
  6. Repeat loops are not yet developed for NairnFEAMPMViz.
  7. Subroutines are not yet developed for NairnFEAMPMViz.
  8. Some functions in expressions are not available in NairnFEAMPMViz.

When writing command files to use in both applications, you should avoid anything not supported in both applications. The key recommendations are to start all variables in #, to end string variables in $, and to use string expressions allowed in NairnFEAMPMViz.

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