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Conformant Array Parameters
A conformant array parameter is a formal array parameter defined by a
conformant array schema (the syntax appears in the HP Pascal/iX Reference
Manual or the HP Pascal/HP-UX Reference Manual). Its actual parameter
must be an array variable that conforms to the schema.
An array variable conforms to a conformant array schema if all of the
following are true:
* The variable and the schema are both PACKED, or neither is PACKED.
* The index types of the variable and the schema are compatible (as
defined in the
HP Pascal/iX Reference Manual or the HP Pascal/HP-UX Reference
Manual).
* The bounds of the index type of the variable are within the bounds
of the index type of the schema.
* The element types of the variable and the schema are the same,
unless the element type of the schema is another schema. If the
element type of the schema is another schema, the element type of
the variable conforms to the other schema.
Example 1
TYPE
itype = 0..20;
jtype = 'a'..'z';
ktype = 0..5;
VAR
var1 : ARRAY [0..10] OF integer;
PROCEDURE p (yes : ARRAY [lb1..ub1 : itype] OF integer;
no1 : PACKED ARRAY [lb3..ub3 : itype] OF integer;
no2 : ARRAY [lb4..ub4 : jtype] OF integer;
no3 : ARRAY [lb5..ub5 : ktype] OF integer;
no4 : ARRAY [lb6..ub6 : itype] OF real;
no5 : ARRAY [lb7..ub7 : itype;
lb8..ub8 : itype] OF integer);
The array variable var1 conforms to the schemas of the conformant array
parameter yes. Var1 and the schema of yes have the same element type,
and 0..10 is within the bounds of itype.
The variable var1 does not conform to the schemas of conformant array
parameters no1, no2, no3, no4, and no5. The following table gives the
reasons for nonconformance.
Parameter Why var1 Does Not Conform to Schema
no1 Schema is PACKED and var1 is not PACKED.
no2 Index types of var1 and schema are not compatible.
no3 Bounds of index type of var1 are not within bounds of index
type of schema.
no4 Element types of var1 and schema are different.
no5 Schema specifies two dimensions, and var has only one
dimension.
Like array declarations, schemas can specify dimensions in syntactically
different but structurally equivalent ways.
Example 2
VAR
var1 : ARRAY [3..5,1..10] OF integer;
var2 : ARRAY [3..5] OF ARRAY [1..10] OF integer;
PROCEDURE p (yes1 : ARRAY [lb1..ub1 : itype] OF
ARRAY [lb2..ub2 : itype] OF integer;
yes2 : ARRAY [lb3..lb3 : itype;
lb4..ub4 : itype] OF integer;
no1 : ARRAY [lb5..ub5 : itype] OF integer;
no2 : ARRAY [lb6..ub6 : itype;
lb7..ub7 : itype;
lb8..ub8 : itype] OF integer);
The declarations of the array variables var1 and var2 are structurally
equivalent, as are the schemas of conformant array parameters yes1 and
yes2. Both var1 and var2 conform to the schemas of yes1 and yes2.
Neither var1 nor var2 conforms to the schema of no1 or no2.
When a conformant array schema is a formal parameter, its bounds are also
formal parameters. They are read-only parameters. The actual parameter
for the formal conformant array schema is an array, and its bounds are
the actual parameters of the formal bounds parameters.
Example 3
TYPE
itype = 0..20;
VAR
v : ARRAY [0..10] OF integer;
PROCEDURE p (x : ARRAY [lb..ub : itype] OF integer);
BEGIN
p(v);
END;
The conformant array schema x is a formal parameter, so its
bounds, lb and ub are read-only formal parameters. The array v is
the actual parameter for x. The lower bound of v, zero, is the
actual parameter for lb. The upper bound of v (10) is the actual
parameter for ub.
When HP Pascal passes an actual parameter to a formal conformant array
parameter of more than one dimension, it also passes one hidden parameter
for each inner dimension that is itself a conformant array. See "Hidden
Parameters" for more information.