4 Information requirements

This clause specifies the information requirements for the Expression application module. The information requirements are specified as the Application Reference Model (ARM) of this application module.

NOTE 1  A graphical representation of the information requirements is given in Annex C.

NOTE 2  The mapping specification is specified in 5.1. It shows how the information requirements are met by using common resources and constructs defined or imported in the MIM schema of this application module.

This clause defines the information requirements to which implementations shall conform using the EXPRESS language as defined in ISO 10303-11. The following begins the Expression_arm schema and identifies the necessary external references.

4.1 Required AM ARMs

The following EXPRESS interface statements specify the elements imported from the ARMs of other application modules.

EXPRESS specification:

*)
USE FROM Generic_expression_arm;    --  ISO/TS 10303-1341



USE FROM Numeric_expression_arm;    --  ISO/TS 10303-1526



REFERENCE FROM Numeric_expression_arm    --  ISO/TS 10303-1526
  (Is_int_expr);
(*



NOTE 1   The schemas referenced above are specified in the following part of ISO 10303:

Generic_expression_arm	ISO/TS 10303-1341
Numeric_expression_arm	ISO/TS 10303-1526
Numeric_expression_arm	ISO/TS 10303-1526

NOTE 2   See Annex C, Figures C.1and C.2 for a graphical representation of this schema.

4.2 ARM entity definitions

This subclause specifies the ARM entities for this module. Each ARM application entity is an atomic element that embodies a unique application concept and contains attributes specifying the data elements of the entity. The ARM entities and definitions are specified below.

4.2.1 Concat_expression   

NOTE    The Concat_expression operator accepts at least two String_expression as operands and evaluates to a string value resulting from the concatenation of all the elements of the operands list. These elements are concatenated in the list order.

EXPRESS specification:

*)
ENTITY Concat_expression
  SUBTYPE OF (String_expression, Multiple_arity_generic_expression);
  SELF\Multiple_arity_generic_expression.operands : LIST[2:?] OF String_expression;
END_ENTITY;
(*

Attribute definitions:

operands: the String_expression to be concatenated.

4.2.2 Format_function   

EXPRESS specification:

*)
ENTITY Format_function
  SUBTYPE OF (String_expression, Binary_generic_expression);
DERIVE
  value_to_format : Generic_expression := SELF\Binary_generic_expression.operands[1];
  format_string : Generic_expression := SELF\Binary_generic_expression.operands[2];
WHERE
  WR1: (('EXPRESSION_ARM.NUMERIC_EXPRESSION') IN TYPEOF(value_to_format)) AND (('EXPRESSION_ARM.STRING_EXPRESSION') IN TYPEOF(format_string));
END_ENTITY;
(*

Attribute definitions:

value_to_format: the Numeric_expression to be formatted.

format_string: the formatting commands that defines the appearance of the result.

Formal propositions:

WR1: the value_to_format shall be a Numeric_expression and the format_string shall be a String_expression.

4.2.3 Index_expression   

NOTE    The Index_expression string operator takes two operands, the string value (represented by the operand attribute) being indexed by the index specification (represented by the index attribute). The resulting string value is the character at position the value of the index operator.

EXPRESS specification:

*)
ENTITY Index_expression
  SUBTYPE OF (String_expression, Binary_generic_expression);
DERIVE
  operand : Generic_expression := SELF\Binary_generic_expression.operands[1];
  index : Generic_expression := SELF\Binary_generic_expression.operands[2];
WHERE
  WR1: ('EXPRESSION_ARM.STRING_EXPRESSION' IN TYPEOF(operand)) AND ('NUMERIC_EXPRESSION_ARM.NUMERIC_EXPRESSION' IN TYPEOF(index));
  WR2: Is_int_expr (index);
END_ENTITY;
(*

Attribute definitions:

operand: the String_expression that represents the STRING.

index: the integer Numeric_expression that indicates the index value.

Formal propositions:

WR1: the first operand shall be a String_expression and the second operand shall be a Numeric_expression.

WR2: the position described by the index operand shall be an integer value.

4.2.4 Like_expression   

EXPRESS specification:

*)
ENTITY Like_expression
  SUBTYPE OF (Comparison_expression);
WHERE
  WR1: ('EXPRESSION_ARM.STRING_EXPRESSION' IN TYPEOF(SELF\Comparison_expression.operands[1])) AND ('EXPRESSION_ARM.STRING_EXPRESSION' IN TYPEOF(SELF\Comparison_expression.operands[2]));
END_ENTITY;
(*

Formal propositions:

WR1: the operand list shall contain two Generic_expressions instances that are String_expression.

4.2.5 Simple_string_expression   

EXPRESS specification:

*)
ENTITY Simple_string_expression
  ABSTRACT SUPERTYPE OF (ONEOF (String_literal,
                                String_variable))
  SUBTYPE OF (String_expression, Simple_generic_expression);
END_ENTITY;
(*

4.2.6 Sql_mappable_defined_function   

EXPRESS specification:

*)
ENTITY Sql_mappable_defined_function
  ABSTRACT SUPERTYPE
  SUBTYPE OF (Defined_function);
END_ENTITY;
(*

4.2.7 String_defined_function   

EXPRESS specification:

*)
ENTITY String_defined_function
  ABSTRACT SUPERTYPE
  SUBTYPE OF (Defined_function, String_expression);
END_ENTITY;
(*

4.2.8 String_expression   

EXPRESS specification:

*)
ENTITY String_expression
  ABSTRACT SUPERTYPE OF (ONEOF (Simple_string_expression,
                                Index_expression,
                                Substring_expression,
                                Concat_expression,
                                Format_function,
                                String_defined_function))
  SUBTYPE OF (Expression);
END_ENTITY;
(*

4.2.9 String_literal   

NOTE    The EXPRESS STRING data type has as its domain sequences of characters.

EXPRESS specification:

*)
ENTITY String_literal
  SUBTYPE OF (Simple_string_expression, Generic_literal);
  the_value : STRING;
END_ENTITY;
(*

Attribute definitions:

the_value: a STRING literal value.

4.2.10 String_variable   

EXPRESS specification:

*)
ENTITY String_variable
  SUBTYPE OF (Simple_string_expression, Variable);
END_ENTITY;
(*

4.2.11 Substring_expression   

NOTE    The Substring_expression string operator takes three operands, the string value (represented by the operand attribute) being indexed by the index specification (represented by the index1 and index2 attributes). The Substring_expression evaluates to a string value of length (index2 - index1 + 1). The resulting string value is equivalent to the sequence of characters at position index1through index2.

EXPRESS specification:

*)
ENTITY Substring_expression
  SUBTYPE OF (String_expression, Multiple_arity_generic_expression);
DERIVE
  operand : Generic_expression := SELF\Multiple_arity_generic_expression.operands[1];
  index1 : Generic_expression := SELF\Multiple_arity_generic_expression.operands[2];
  index2 : Generic_expression := SELF\Multiple_arity_generic_expression.operands[3];
WHERE
  WR1: ('EXPRESSION_ARM.STRING_EXPRESSION' IN TYPEOF(operand)) AND ('EXPRESSION_ARM.NUMERIC_EXPRESSION' IN TYPEOF(index1)) AND ('EXPRESSION_ARM.NUMERIC_EXPRESSION' IN TYPEOF(index2));
  WR2: SIZEOF(SELF\Multiple_arity_generic_expression.operands)=3;
  WR3: Is_int_expr (index1);
  WR4: Is_int_expr (index2);
END_ENTITY;
(*

Attribute definitions:

operand: the String_expression from which a substring is extracted.

index1: the Numeric_expression that indicates the low bound of the substring in operand.

index2: the Numeric_expression that indicates the high bound of the substring in operand.

Formal propositions:

WR1: operand shall be a String_expression, index1 and index2 shall be a Numeric_expression.

WR2: the Substring_expression operands LIST shall contain three elements.

WR3: the index1 shall evaluate to an INTEGER value.

WR4: the index2 shall evaluate to an INTEGER value.

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