Multitech MTPSR1-202ST Betriebsanweisung PDF herunterladen (Seite 61)

Appendixes

MTPSR1-202ST

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

Argument to procedures can be passed by value or address. To pass an argument by address, prefix

the argument name in the formal parameter list by the keyword VAR; otherwise the argument is

passed by value. Only variables can be passed by address. Expressions like A+B, where A and B

are integer variables can be passed by value but cannot be passed by address.

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