RE: [sv-cc] assignment pattern expressions information model efficiency

I like it !   I would perhaps choose to name 'vpiAssocExpr' as
'vpiAssignPatternKey' or
something that links it more directly with it's use here- unless it
would have other
similar applications elsewhere.
-Chuck


________________________________

	From: owner-sv-cc@eda.org [mailto:owner-sv-cc@eda.org] On Behalf
Of francoise martinolle
	Sent: Tuesday, April 25, 2006 11:50 PM
	To: 'SV-CC'
	Subject: [sv-cc] assignment pattern expressions information
model efficiency
	
	
	When we defined the information model for assignment pattern
expressions we decided that it 
	would be represented as an operation which operands would be the
expressions inside the assignment pattern
	expression of an equivalent assignment pattern expression using
the positional notation.
	See note 6 of diagram 27.39.
	 
	This is problematic when we have a default assignment pattern
expression assigned to a very large
	array:
	Ex:
	 
	int ARR [100][100] = '{default :0};
	There would be 10,000 operands returned for the iteration each
representing the value 0.
	 
	Same issue arises with the type key:
	 
	int ARR [100][100] = '{int: 0};
	 
	Perhaps we should define a more efficient (compact) model to
represent values assigned to multiple elements in assignment patterns.
	 
	An idea would be to represent the index, type, member and
default value as associations.
	For example,  I would introduce a new expression of type
vpiAssocExpr which could be returned as an operand of the 
	vpiAssignPatternOp operation. From a vpiAssocExpr, one can
access the property vpiKey which would 
	return either vpiDefault, vpiIndex, vpiMember or vpiType,
Additionally the expression associated with the association 
	can also be obtained with a vpiExpr method. The key itself can
be obtained with a vpiKeyExpr method
	 
	vpiOperation ---vpiOperand-->> vpiAssocExpr                 
	                                                 vpiKey
(vpiDefaultKey, vpiIndexKey, vpiTypeKey, vpiMemberKey)
	                                                 ------->
vpiKeyExpr
	                                                 -------->
vpiExpr 
	 
	 
	In the example above, vpiOperand would only return an operand of
type vpiAssocExpr. The vpiExpr applied
	to the vpiAssocExpr would return the constant 0, the vpiKey
property would return vpiDefault, the vpiKeyExpr would return NULL.
	 
	Ex:
	 
	int arr [1000] = '{0: 1, 100: 3, int:2}
	For this example, we would only get 3 operands for the
iteration, 
	   vpiAssocExpr 
	             vpiKey = vpiIndexKey
	             vpiKeyExpr = vpiConstant for 0
	             vpiExpr = vpiConstant 1
	 
	
	   vpiAssocExpr 
	             vpiKey = vpiIndexKey
	             vpiKeyExpr = vpiConstant for 100
	             vpiExpr = vpiConstant 1
	 
	  
	   vpiAssocExpr 
	             vpiKey = vpiTypeKey
	             vpiKeyExpr = vpiTypespec for "int"
	             vpiExpr = vpiConstant 2
	 
	 
	We would not require that assignmentPattern expressions be
represented with assoc expressions. We could still leave the possibility
	for an implementation to represent an assignment pattern
expression as a full expanded positional assignment pattern. 
	Comments?
	 
	Francoise
	       '