Schema: iso13584_generic_expressions_schema

Source : ISO 13584-20



SCHEMA iso13584_generic_expressions_schema;


ENTITY binary_generic_expression
  ABSTRACT SUPERTYPE
  SUBTYPE OF (generic_expression);
  operands : LIST[2:2] OF generic_expression;
END_ENTITY;

ENTITY environment;
  syntactic_representation : generic_variable;
  semantics : variable_semantics;
END_ENTITY;

ENTITY generic_expression
  ABSTRACT SUPERTYPE OF (ONEOF (simple_generic_expression,
                                unary_generic_expression,
                                binary_generic_expression,
                                multiple_arity_generic_expression));
WHERE
  WR1: is_acyclic(SELF);
END_ENTITY;

ENTITY generic_literal
  ABSTRACT SUPERTYPE
  SUBTYPE OF (simple_generic_expression);
END_ENTITY;

ENTITY generic_variable
  ABSTRACT SUPERTYPE
  SUBTYPE OF (simple_generic_expression);
INVERSE
  interpretation : environment FOR syntactic_representation;
END_ENTITY;

ENTITY multiple_arity_generic_expression
  ABSTRACT SUPERTYPE
  SUBTYPE OF (generic_expression);
  operands : LIST[2:?] OF generic_expression;
END_ENTITY;

ENTITY simple_generic_expression
  ABSTRACT SUPERTYPE OF (ONEOF (generic_literal,
                                generic_variable))
  SUBTYPE OF (generic_expression);
END_ENTITY;

ENTITY unary_generic_expression
  ABSTRACT SUPERTYPE
  SUBTYPE OF (generic_expression);
  operand : generic_expression;
END_ENTITY;

ENTITY variable_semantics
  ABSTRACT SUPERTYPE ;
END_ENTITY;

FUNCTION acyclic
 (arg1 : generic_expression; arg2 : SET[0:?] OF generic_expression) : BOOLEAN; 
LOCAL
	result: BOOLEAN := TRUE;
END_LOCAL;

IF ('ISO13584_GENERIC_EXPRESSIONS_SCHEMA.SIMPLE_GENERIC_EXPRESSION'
	IN TYPEOF (arg1)) 
THEN
	RETURN (TRUE);
END_IF;

IF arg1 IN arg2 
THEN 
	RETURN (FALSE);
END_IF;

IF 'ISO13584_GENERIC_EXPRESSIONS_SCHEMA.UNARY_GENERIC_EXPRESSION' 
	IN TYPEOF (arg1) 
THEN 
	RETURN 
	(acyclic(arg1\unary_generic_expression.operand,arg2+[arg1]));
END_IF;

IF 'ISO13584_GENERIC_EXPRESSIONS_SCHEMA.BINARY_GENERIC_EXPRESSION' 
	IN TYPEOF (arg1) 
THEN 
	RETURN 
	(acyclic(arg1\binary_generic_expression.operands[1],arg2+[arg1])
	AND
	acyclic(arg1\binary_generic_expression.operands[2],arg2+[arg1]));
END_IF;

IF 
'ISO13584_GENERIC_EXPRESSIONS_SCHEMA.MULTIPLE_ARITY_GENERIC_EXPRESSION' 
	IN TYPEOF (arg1) 
THEN 
	result := TRUE;
	REPEAT i := 1 TO 
			SIZEOF (arg1\multiple_arity_generic_expression.operands);
		result := result AND
		acyclic(arg1\multiple_arity_generic_expression.operands[i], arg2+[arg1]);
	END_REPEAT;

	RETURN (result);
END_IF;
	RETURN (result);
END_FUNCTION;

FUNCTION is_acyclic
 (arg : generic_expression) : BOOLEAN; 
RETURN (acyclic (arg, []));
END_FUNCTION;

FUNCTION used_variables
 (arg : generic_expression) : SET[0:?] OF generic_variable; 
LOCAL
	result : SET OF generic_variable := [];
END_LOCAL;

IF 'ISO13584_GENERIC_EXPRESSIONS_SCHEMA.GENERIC_VARIABLE' 
	IN TYPEOF (arg) 
THEN 
	RETURN ([arg]);
END_IF;

IF 'ISO13584_GENERIC_EXPRESSIONS_SCHEMA.UNARY_GENERIC_EXPRESSION' 
	IN TYPEOF (arg)
THEN 
	RETURN (used_variables (arg\unary_generic_expression.operand));
END_IF;

IF 'ISO13584_GENERIC_EXPRESSIONS_SCHEMA.BINARY_GENERIC_EXPRESSION'
	IN TYPEOF (arg)
THEN 
	RETURN(used_variables(arg\binary_generic_expression.operands[1])
		+ used_variables (arg\binary_generic_expression.operands[2]));
END_IF;

IF
'ISO13584_GENERIC_EXPRESSIONS_SCHEMA.MULTIPLE_ARITY_GENERIC_EXPRESSION' 
	IN TYPEOF (arg)
THEN
	REPEAT i := 1 TO 
		SIZEOF(arg\multiple_arity_generic_expression.operands);
		result := result + used_variables(
			arg\multiple_arity_generic_expression.operands[i]);
	END_REPEAT;
	
	RETURN (result);
END_IF;
RETURN ([ ]);
END_FUNCTION;

END_SCHEMA;  -- iso13584_generic_expressions_schema