Multi-Tech Systems MTASR3-200 Appendix B - Script Language, Script Language Grammar

Appendices

MTASR3-200

Appendix B - Script Language

The script file can be used to automate certain operations. The script file is a text file containing a

sequence of commands. The structure of a script file is succinctly expressed by the following

grammar.

Script Language Grammar

<declarations> ={<var_type> <identifier> {, <identifier> } ; }

<var_type> =INTEGER I STRING

<statement_list> ={<statement>}

<statement> =<elementary_statement> I <if_statement> I<for_statement> I

<while_statement> I <switch_statement>

<if_statement> =IF <expression> THEN <statement_list> {ELSE<statement_list> } ENDIF

<for_statement> =FOR <identifier>=<expression> TO IDOWNTO <expression} STEP

<expression> / DO <statement_list> ENDFOR

<while_statement> =WHILE <expression> DO <statement_list> ENDWHILE

<switch_statement> =SWITCH <expression> {CASE <integer_const> <statement_list> I

CASE <string_const> <statement_list> I

DEFAULT <statement_list> }

ENDSWITCH

<elementary_statement> =<identifier> = <expression> ; I <identifier> / (<expression>

{,<expression> } ) /; I GOTO <identifier> ; I <identifier> : I ;

<expression> =<expression> OPERATOR <expression> I {<expression> } I /<expression>I

- <expression> I<identifier> / (<expression> {, <expression> } ) /

OPERATOR = < I <= I > I >= I == I != I && I II I + I - I * I / I !

<proc_declaration> =PROC <identifier>/(<parameter_list>)} { :<vartype> };FORWARD ;

<proc_declaration> =PROC <identifier>/(<parameter_list>)} / : <vartype> / ;

<declarations> <statement_list>ENDPROC

<parameter_list> =<argument_list> { ; <argument_list>}

<argument_list> ={VAR} <var_type> <identifier> {<identifier>}

Execution starts at the PROC main. PROC main cannot have any arguments. All the variables have

to be declared before use. All procedures must be declared before calling. Recursion is allowed in

procedures.

To define mutually recursive procedures, use the FORWARD directive to indicate that the procedure

body is defined later in the source file. Procedures defined with the FORWARD directive should have

all the parameters and return value (if any) specified, the actual definition of the procedure body

should not contain the formal parameter list or the return value. An example of forward defined

procedures is given below:

proc a(integer x,y) : integer,forward:

proc b(integer u,v) : integer,forward:

proc a; integer t;

/*Some more code here. */

t=b(x,y);

/*Some more code here. */

return(t);

endproc

proc b; return(a(u,v);

endproc