Scripting Language Syntax
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.
- Command Line Syntax: the format of a single command line.
- Variable Names: the language allows variables and variable arrays.
- Expression Syntax: the language allows expressions for making calculations and setting arguments.
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
- 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).
- 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. - 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
- 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
Subroutines can be defined at the start of the commands and called with optional parameters.
- <a href="sub.html">Sub</a> ... <a href="endsub.html">EndSub</a>: Define a subroutine.
- <a href="gosub.html">GoSub</a>: Call a <a href="sub.html">subroutine</a>.
- <a href="return.html">Return</a>: Return from a <a href="sub.html">subroutine</a>.
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.