# editAttr_udf_2
# written by John Dannenhoffer

# command blocks take the form:
#   PATBEG  var   ncopy        (optional)
#   type    oper  attr1 ...
#   bool    oper  attr1 ...    (optional)
#   ...                        (optional)
#   action        attr1 ...
#   PATEND                     (only if there is a matching PATBEG)
#
# where:
#   var                  loop variable (cannot be same as one outside)
#   ncopy                the number of copies of the pattern
#
# where type can be:
#   NODE                 to select Node(s)
#   EDGE                 to select Edge(s)
#   FACE                 to select Face(s)
#
# where oper can be:
#   HAS                  matches attr1 and attr2 and ...
#   ADJ2NODE             adjacent to a  Node that matches attr1 and attr2 and ...
#   ADJ2EDGE             adjacent to an Edge that matches attr1 and attr2 and ...
#   ADJ2FACE             adjacent to a  Face that matches attr1 and attr2 and ...
#
# where bool can be:
#   AND                  this condition must also hold
#   ANDNOT               this condition must not  hold
#
# where attr1 is in the form:
#   attrName=attrValue   matches the name and the value
#   attributeName=*      * is a wildcard
#   attributeName=       (only in SET) to delete the attrName
#
# where action can be:
#   SET                  sets attr1 and attr2 and ...
#   ADD                  adds attra and attr2 and ...
#
# #                      introduces a comment
# END                    the remainder of the file is ignored
#
# note: all command can be either UPPERCASE or lowercase, but not MixedCase
# note: white-space at beginning of a line is ignored
# note: tokens are delimited with white-spaces
# note: editAttr has access to variables defined in the .csm script

# make three adjacent boxes
BOX       0  0  0  0  1  1
BOX       1  0  0  0  1  1
BOX       2  0  0  0  1  1
BOX       3  0  0  0  1  1
RULE

# label the Faces face_1, face_2, ...
# note:  !$face_+iface means the expression (attribute value)
#        is the concatenation of the string "face_" and the value of iface
PATBEG    iface  @nface
   SELECT    FACE  @nbody  iface
   ATTRIBUTE name  !$face_+iface
PATEND

# select the Body so that the value for @nface will be correct below
SELECT    BODY

# make the odd-named Faces red
UDPRIM    editAttr  filename <<
   PATBEG    jface  @nface/2
      # the attribute value is the concatenation of the
      #     string "face_" and the value (2*jface-1)
      FACE   HAS    name=!$face_+(2*jface-1)
      SET           _color=red
   PATEND
>>

END