From: Chris Hanson <org/chris-hanson/cph>
Date: Wed, 7 Feb 1990 23:25:58 +0000 (+0000)
Subject: Implement new record proposal.
X-Git-Tag: 20090517-FFI~11543
X-Git-Url: https://birchwood-abbey.net/git?a=commitdiff_plain;h=05cb1dca7d44a3f91f755833c9764f6af297f997;p=mit-scheme.git

Implement new record proposal.
---

diff --git a/v7/src/runtime/record.scm b/v7/src/runtime/record.scm
index 572ff3f2a..6ac6ba550 100644
--- a/v7/src/runtime/record.scm
+++ b/v7/src/runtime/record.scm
@@ -1,8 +1,8 @@
 #| -*-Scheme-*-
 
-$Header: /Users/cph/tmp/foo/mit-scheme/mit-scheme/v7/src/runtime/record.scm,v 1.2 1989/02/28 18:36:10 cph Rel $
+$Header: /Users/cph/tmp/foo/mit-scheme/mit-scheme/v7/src/runtime/record.scm,v 1.3 1990/02/07 23:25:58 cph Exp $
 
-Copyright (c) 1989 Massachusetts Institute of Technology
+Copyright (c) 1989, 1990 Massachusetts Institute of Technology
 
 This material was developed by the Scheme project at the Massachusetts
 Institute of Technology, Department of Electrical Engineering and
@@ -33,80 +33,144 @@ promotional, or sales literature without prior written consent from
 MIT in each case. |#
 
 ;;;; Records
-;;; written by Jonathan Rees
+;;; adapted from JAR's implementation
+;;; conforms to R4RS proposal
 
 (declare (usual-integrations))
 
-(define (make-record-type type-id field-names)
-  (let ((size (+ (length field-names) 1)))
-
-    (define (constructor names)
-      (let ((number-of-inits (length names))
-	    (indexes (map field-index names)))
-	(lambda field-values
-	  (if (not (= (length field-values) number-of-inits))
-	      (error "wrong number of arguments to record constructor"
-		     field-values type-id names))
-	  (let ((record (make-vector size)))
-	    (vector-set! record 0 the-descriptor)
-	    (for-each (lambda (index value) (vector-set! record index value))
-		      indexes
-		      field-values)
-	    record))))
-
-    (define (predicate obj)
-      (and (vector? obj)
-	   (= (vector-length obj) size)
-	   (eq? (vector-ref obj 0) the-descriptor)))
+(define (make-record-type type-name field-names)
+  (let ((size (+ (length field-names) 1))
+	(the-descriptor (make-vector 7)))
+
+    (define (predicate object)
+      (and (vector? object)
+	   (= (vector-length object) size)
+	   (eq? (vector-ref object 0) the-descriptor)))
 
     (define (guarantee record)
       (if (not (predicate record))
-	  (error "invalid argument to record accessor" record type-id)))
-
-    (define (accessor name)
-      (let ((index (field-index name)))
-	(lambda (record)
-	  (guarantee record)
-	  (vector-ref record index))))
-
-    (define (updater name)
-      (let ((index (field-index name)))
-	(lambda (record new-value)
-	  (guarantee record)
-	  (vector-set! record index new-value))))
-
-    (define (describe record)
-      (guarantee record)
-      (map (lambda (name) (list name (vector-ref record (field-index name))))
-	   field-names))
+	  (error "invalid argument to record accessor" record type-name)))
 
     (define (field-index name)
       (let loop ((names field-names) (index 1))
-	(cond ((null? names) (error "bad field name" name))
-	      ((eq? name (car names)) index)
-	      (else (loop (cdr names) (+ index 1))))))
-
-    (define (the-descriptor request)
-      (case request
-	((CONSTRUCTOR) constructor)
-	((PREDICATE) predicate)
-	((ACCESSOR) accessor)
-	((UPDATER) updater)
-	(else (error "invalid request to record type" type-id request))))
-
+	(if (null? names)
+	    (error "bad field name" name))
+	(if (eq? name (car names))
+	    index
+	    (loop (cdr names) (+ index 1)))))
+
+    (vector-set! the-descriptor 0 "record-type-descriptor")
+    (vector-set! the-descriptor 1 predicate)
+    (vector-set! the-descriptor 2
+      (lambda (names)
+	(let ((number-of-inits (length names))
+	      (indexes (map field-index names)))
+	  (lambda field-values
+	    (if (not (= (length field-values) number-of-inits))
+		(error "wrong number of arguments to record constructor"
+		       field-values type-name names))
+	    (let ((record (make-vector size)))
+	      (vector-set! record 0 the-descriptor)
+	      (for-each (lambda (index value)
+			  (vector-set! record index value))
+			indexes
+			field-values)
+	      record)))))
+    (vector-set! the-descriptor 3
+      (lambda (name)
+	(let ((index (field-index name)))
+	  (lambda (record)
+	    (guarantee record)
+	    (vector-ref record index)))))
+    (vector-set! the-descriptor 4
+      (lambda (name)
+	(let ((index (field-index name)))
+	  (lambda (record new-value)
+	    (guarantee record)
+	    (vector-set! record index new-value)))))
+    (vector-set! the-descriptor 5 type-name)
+    (vector-set! the-descriptor 6 (list-copy field-names))
     (unparser/set-tagged-vector-method! the-descriptor
-					(unparser/standard-method type-id))
-    (named-structure/set-tag-description! the-descriptor describe)
+					(unparser/standard-method type-name))
+    (named-structure/set-tag-description! the-descriptor
+      (lambda (record)
+	(guarantee record)
+	(map (lambda (name)
+	       (list name (vector-ref record (field-index name))))
+	     field-names)))
     the-descriptor))
-
-(define (record-constructor record-type names)
-  ((record-type 'CONSTRUCTOR) names))
+
+(define (record-constructor record-type #!optional field-names)
+  (guarantee-record-type record-type)
+  ((vector-ref record-type 2)
+   (if (default-object? field-names)
+       (record-type-field-names record-type)
+       field-names)))
 
 (define (record-predicate record-type)
-  (record-type 'PREDICATE))
+  (guarantee-record-type record-type)
+  (vector-ref record-type 1))
 
 (define (record-accessor record-type field-name)
-  ((record-type 'ACCESSOR) field-name))
+  (guarantee-record-type record-type)
+  ((vector-ref record-type 3) field-name))
 
 (define (record-updater record-type field-name)
-  ((record-type 'UPDATER) field-name))
\ No newline at end of file
+  (guarantee-record-type record-type)
+  ((vector-ref record-type 4) field-name))
+
+(define (set-record-type-unparser-method! record-type method)
+  (guarantee-record-type record-type)
+  (unparser/set-tagged-vector-method! record-type method))
+
+;;; Abstraction-Breaking Operations
+
+(define record-type?
+  (let ((record-type (make-record-type "foo" '())))
+    (let ((size (vector-length record-type))
+	  (tag (vector-ref record-type 0)))
+      (unparser/set-tagged-vector-method!
+       tag
+       (unparser/standard-method 'RECORD-TYPE-DESCRIPTOR
+	 (lambda (state record-type)
+	   (unparse-object state (vector-ref record-type 5)))))
+      (named-structure/set-tag-description! tag
+	(lambda (record-type)
+	  (guarantee-record-type record-type)
+	  `((PREDICATE ,(vector-ref record-type 1))
+	    (CONSTRUCTOR-CONSTRUCTOR ,(vector-ref record-type 2))
+	    (ACCESSOR-CONSTRUCTOR ,(vector-ref record-type 3))
+	    (UPDATER-CONSTRUCTOR ,(vector-ref record-type 4))
+	    (TYPE-NAME ,(vector-ref record-type 5))
+	    (FIELD-NAMES ,(vector-ref record-type 6)))))
+      (lambda (object)
+	(and (vector? object)
+	     (= (vector-length object) size)
+	     (eq? (vector-ref object 0) tag))))))
+
+(define (guarantee-record-type object)
+  (if (not (record-type? object))
+      (error "not a record type descriptor" object))
+  object)
+
+(define (record-type-name record-type)
+  (guarantee-record-type record-type)
+  (vector-ref record-type 5))
+
+(define (record-type-field-names record-type)
+  (guarantee-record-type record-type)
+  (list-copy (vector-ref record-type 6)))
+
+(define (record? object)
+  (and (vector? object)
+       (not (zero? (vector-length object)))
+       (record-type? (vector-ref object 0))))
+
+(define (guarantee-record object)
+  (if (not (record? object))
+      (error "not a record" object))
+  object)
+
+(define (record-type-descriptor record)
+  (guarantee-record record)
+  (vector-ref record 0))
\ No newline at end of file