14.10 Scanobjects Interface

ORIGIN '~beta/basiclib/betaenv';
BODY 'private/scanobjectsbody';

(* Support for scanning all objects at a point of time
 * in the execution of any BETA program.
 *
 * If you specialize the 'callback' virtual, it will be
 * executed once for each object visited, with 'obj'
 * referring to the object being visited. It will
 * never be executed for a non-object, such as a
 * repetition etc.
 *
 * The pattern variable 'root' is used to select
 * which objects to visit: an object is visited iff
 * it is an instance of a specialization of the
 * pattern denoted by 'root'. If 'root' is NONE,
 * all objects and non-objects are visited. If
 * (root## = object##), all objects are visited.
 *
 * If 'printVisited' is true, a message is printed
 * describing the pattern of each visited object,
 * and giving the category of each visited non-object,
 * such as '[Value Repetition]'.
 *
 * When 'printVisited' is true, other booleans can be
 * used to enhance the output for objects: If
 * 'printOrigin' is true, the origin of each
 * visited object is printed. If 'printSize'
 * is true, the size in bytes of each visited
 * object is printed. 
 *
 * If a garbage collection runs during a scan, it
 * will be aborted with an error message, but the
 * program continues otherwise unaffected. To
 * avoid this, try to create as few objects as
 * possible in callback. (If callback is not
 * specialized, it will not get called, and no
 * objects will be created during the scan.)
 *
 * COPYRIGHT
 *       Copyright Mjolner Informatics, 1994-96
 *       All rights reserved.
 *)

--- LIB: attributes ---

scanCallback:
  (# obj: ^object;
  enter obj[]
  do INNER
  #);

scanPrefix:
  (# callback:< scanCallback;
     root: ##object;
     printVisited,printOrigin,printSize: @boolean;
  do INNER
  #);

scanIOA:  scanPrefix(# do ... #);
scanAOA:  scanPrefix(# do ... #);
scanLVRA: scanPrefix(# do ... #);

ScanRefsToPrefix:
  (# target: ^Object;
     callback:< scanCallback;
     printName: @Boolean;
     skipGC: @Boolean; (* Set to true when using within the other scans *)
  enter target[]
  do INNER
  #);

(* Scans IOA only for references to the given target *)
scanRefsToObject: ScanRefsToPrefix(# do ... #)