;;;; -*- Mode: Lisp; Syntax: ANSI-Common-Lisp; Base: 10 -*-
;;;; *************************************************************************
;;;; FILE IDENTIFICATION
;;;;
;;;; Name:          equal.lisp
;;;; Purpose:       Generalized equal function for KMRCL package
;;;; Programmer:    Kevin M. Rosenberg
;;;; Date Started:  Apr 2000
;;;;
;;;; $Id: equal.lisp,v 1.1 2002/10/12 06:10:17 kevin Exp $
;;;;
;;;; This file, part of KMRCL, is Copyright (c) 2002 by Kevin M. Rosenberg
;;;;
;;;; KMRCL users are granted the rights to distribute and use this software
;;;; as governed by the terms of the Lisp Lesser GNU Public License
;;;; (http://opensource.franz.com/preamble.html), also known as the LLGPL.
;;;; *************************************************************************


(in-package :kmrcl)
(declaim (optimize (speed 3) (safety 1) (compilation-speed 0) (debug 3)))

  
(defun generalized-equal (obj1 obj2)
  (if (not (equal (type-of obj1) (type-of obj2)))
      (progn
	(terpri)
	(describe obj1)
	(describe obj2)
	nil)
    (typecase obj1
      (double-float
       (let ((diff (abs (/ (- obj1 obj2) obj1))))
	 (if (> diff (* 10 double-float-epsilon))
	     nil
	   t)))
      (complex
       (and (generalized-equal (realpart obj1) (realpart obj2))
	    (generalized-equal (imagpart obj1) (imagpart obj2))))
      (standard-xstructure
       (generalized-equal-fielded-object obj1 obj2))
      (standard-object
       (generalized-equal-fielded-object obj1 obj2))
      (hash-table
       (generalized-equal-hash-table obj1 obj2)
       )
      (function
       (generalized-equal-function obj1 obj2))
      (string
       (string= obj1 obj2))
      (array
       (generalized-equal-array obj1 obj2))
      (t
       (equal obj1 obj2)))))


(defun generalized-equal-function (obj1 obj2)
  (string= (function-to-string obj1) (function-to-string obj2)))

(defun generalized-equal-array (obj1 obj2)
  (block test
    (when (not (= (array-total-size obj1) (array-total-size obj2)))
      (return-from test nil))
    (dotimes (i (array-total-size obj1))
      (unless (generalized-equal (aref obj1 i) (aref obj2 i))
	(return-from test nil)))
    (return-from test t)))

(defun generalized-equal-hash-table (obj1 obj2)
  (block test
    (when (not (= (hash-table-count obj1) (hash-table-count obj2)))
      (return-from test nil))
    (maphash
     #'(lambda (k v)
	 (multiple-value-bind (value found) (gethash k obj2)
	   (unless (and found (generalized-equal v value))
	     (return-from test nil))))
     obj1)
    (return-from test t)))

(defun generalized-equal-fielded-object (obj1 obj2)
  (block test
    (when (not (equal (class-of obj1) (class-of obj2)))
      (return-from test nil))
    (dolist (field (class-slot-names (class-name (class-of obj1))))
      (unless (generalized-equal (slot-value obj1 field) (slot-value obj2 field))
	(return-from test nil)))
    (return-from test t)))

#+(or allegro lispworks)
(defun class-slot-names (class-name)
  "Given a CLASS-NAME, returns a list of the slots in the class."
  (mapcar #'clos:slot-definition-name
	  (clos:class-slots (find-class class-name))))

#-(or allegro lispworks)
(defun class-slot-names (class-name)
  (warn "class-slot-names not supported on this platform"))


(defun function-to-string (obj)
  "Returns the lambda code for a function. Relies on
Allegro implementation-dependent features."
  (multiple-value-bind (lambda closurep name) (function-lambda-expression obj)
    (declare (ignore closurep))
    (if lambda
	  (format nil "#'~s" lambda)
      (if name
	  (format nil "#'~s" name)
	(progn
	  (print obj)
	  (break))))))