Added an R7RS-compatible implementation and fixed a couple of bugs.

srfi/128.body1.scm

@@ -0,0 +1,362 @@
+;;; Copyright (C) John Cowan (2015). All Rights Reserved.
+;;; 
+;;; Permission is hereby granted, free of charge, to any person
+;;; obtaining a copy of this software and associated documentation
+;;; files (the "Software"), to deal in the Software without
+;;; restriction, including without limitation the rights to use,
+;;; copy, modify, merge, publish, distribute, sublicense, and/or
+;;; sell copies of the Software, and to permit persons to whom the
+;;; Software is furnished to do so, subject to the following
+;;; conditions:
+;;; 
+;;; The above copyright notice and this permission notice shall be
+;;; included in all copies or substantial portions of the Software.
+;;; 
+;;; THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+;;; EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES
+;;; OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
+;;; NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
+;;; HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
+;;; WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+;;; FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
+;;; OTHER DEALINGS IN THE SOFTWARE. 
+
+;;;; Main part of the SRFI 114 reference implementation
+
+;;; "There are two ways of constructing a software design: One way is to
+;;; make it so simple that there are obviously no deficiencies, and the
+;;; other way is to make it so complicated that there are no *obvious*
+;;; deficiencies." --Tony Hoare
+
+;;; Syntax (because syntax must be defined before it is used, contra Dr. Hardcase)
+
+;; Arithmetic if
+(define-syntax comparator-if<=>
+  (syntax-rules ()
+    ((if<=> a b less equal greater)
+     (comparator-if<=> (make-default-comparator) a b less equal greater))
+    ((comparator-if<=> comparator a b less equal greater)
+     (cond
+       ((=? comparator a b) equal)
+       ((<? comparator a b) less)
+       (else greater)))))
+
+;; Upper bound of hash functions is 2^25-1
+(define-syntax hash-bound
+  (syntax-rules ()
+    ((hash-bound) 33554432)))
+
+(define %salt% (make-parameter 16064047))
+
+(define-syntax hash-salt
+   (syntax-rules ()
+     ((hash-salt) (%salt%))))
+
+(define-syntax with-hash-salt
+  (syntax-rules ()
+    ((with-hash-salt new-salt hash-func obj)
+     (parameterize ((%salt% new-salt)) (hash-func obj)))))
+
+;;; Definition of comparator records with accessors and basic comparator
+
+(define-record-type comparator
+  (make-raw-comparator type-test equality ordering hash ordering? hash?)
+  comparator?
+  (type-test comparator-type-test-predicate)
+  (equality comparator-equality-predicate)
+  (ordering comparator-ordering-predicate)
+  (hash comparator-hash-function)
+  (ordering? comparator-ordered?)
+  (hash? comparator-hashable?))
+
+;; Public constructor
+(define (make-comparator type-test equality ordering hash)
+  (make-raw-comparator
+    (if (eq? type-test #t) (lambda (x) #t) type-test)
+    (if (eq? equality #t) (lambda (x y) (eqv? (ordering x y) 0)) equality)
+    (if ordering ordering (lambda (x y) (error "ordering not supported")))
+    (if hash hash (lambda (x y) (error "hashing not supported")))
+    (if ordering #t #f)
+    (if hash #t #f)))
+
+;;; Invokers
+
+;; Invoke the test type
+(define (comparator-test-type comparator obj)
+  ((comparator-type-test-predicate comparator) obj))
+
+;; Invoke the test type and throw an error if it fails
+(define (comparator-check-type comparator obj)
+  (if (comparator-test-type comparator obj)
+    #t
+    (error "comparator type check failed" comparator obj)))
+
+;; Invoke the hash function
+(define (comparator-hash comparator obj)
+  ((comparator-hash-function comparator) obj))
+
+;;; Comparison predicates
+
+;; Binary versions for internal use
+
+(define (binary=? comparator a b)
+  ((comparator-equality-predicate comparator) a b))
+
+(define (binary<? comparator a b)
+  ((comparator-ordering-predicate comparator) a b))
+
+(define (binary>? comparator a b)
+  (binary<? comparator b a))
+
+(define (binary<=? comparator a b)
+  (not (binary>? comparator a b)))
+
+(define (binary>=? comparator a b)
+  (not (binary<? comparator a b)))
+
+;; General versions for export
+
+(define (=? comparator a b . objs)
+  (let loop ((a a) (b b) (objs objs))
+    (and (binary=? comparator a b)
+	 (if (null? objs) #t (loop b (car objs) (cdr objs))))))
+
+(define (<? comparator a b . objs)
+  (let loop ((a a) (b b) (objs objs))
+    (and (binary<? comparator a b)
+	 (if (null? objs) #t (loop b (car objs) (cdr objs))))))
+
+(define (>? comparator a b . objs)
+  (let loop ((a a) (b b) (objs objs))
+    (and (binary>? comparator a b)
+	 (if (null? objs) #t (loop b (car objs) (cdr objs))))))
+
+(define (<=? comparator a b . objs)
+  (let loop ((a a) (b b) (objs objs))
+    (and (binary<=? comparator a b)
+	 (if (null? objs) #t (loop b (car objs) (cdr objs))))))
+
+(define (>=? comparator a b . objs)
+  (let loop ((a a) (b b) (objs objs))
+    (and (binary>=? comparator a b)
+	 (if (null? objs) #t (loop b (car objs) (cdr objs))))))
+
+
+;;; Simple ordering and hash functions
+
+(define (boolean<? a b)
+  ;; #f < #t but not otherwise
+  (and (not a) b))
+
+
+(define (boolean-hash obj)
+  (if obj (%salt%) 0))
+
+(define (char-hash obj)
+  (modulo (* (%salt%) (char->integer obj)) (hash-bound)))
+
+(define (char-ci-hash obj)
+  (modulo (* (%salt%) (char->integer (char-foldcase obj))) (hash-bound)))
+
+(define (number-hash obj)
+  (cond
+    ((nan? obj) (%salt%))
+    ((and (infinite? obj) (positive? obj)) (* 2 (%salt%)))
+    ((infinite? obj) (* (%salt%) 3))
+    ((real? obj) (abs (exact (round obj))))
+    (else (+ (number-hash (real-part obj)) (number-hash (imag-part obj))))))
+
+;; Lexicographic ordering of complex numbers
+(define (complex<? a b)
+  (if (= (real-part a) (real-part b))
+    (< (imag-part a) (imag-part b))
+    (< (real-part a) (real-part b))))
+
+(define (string-ci-hash obj)
+    (string-hash (string-foldcase obj)))
+
+(define (symbol<? a b) (string<? (symbol->string a) (symbol->string b)))
+
+(define (symbol-hash obj)
+  (string-hash (symbol->string obj)))
+
+;;; Wrapped equality predicates
+;;; These comparators don't have ordering functions.
+
+(define (make-eq-comparator)
+  (make-comparator #t eq? #f default-hash))
+
+(define (make-eqv-comparator)
+  (make-comparator #t eqv? #f default-hash))
+
+(define (make-equal-comparator)
+  (make-comparator #t equal? #f default-hash))
+
+;;; Sequence ordering and hash functions
+;; The hash functions are based on djb2, but
+;; modulo 2^25 instead of 2^32 in hopes of sticking to fixnums.
+
+(define (make-hasher)
+  (let ((result (%salt%)))
+    (case-lambda
+     (() result)
+     ((n) (set! result (+ (modulo (* result 33) (hash-bound)) n))
+          result))))
+
+;;; Pair comparator
+(define (make-pair-comparator car-comparator cdr-comparator)
+   (make-comparator
+     (make-pair-type-test car-comparator cdr-comparator)
+     (make-pair=? car-comparator cdr-comparator)
+     (make-pair<? car-comparator cdr-comparator)
+     (make-pair-hash car-comparator cdr-comparator)))
+
+(define (make-pair-type-test car-comparator cdr-comparator)
+  (lambda (obj)
+    (and (pair? obj)
+         (comparator-test-type car-comparator (car obj))
+         (comparator-test-type cdr-comparator (cdr obj)))))
+
+(define (make-pair=? car-comparator cdr-comparator)
+   (lambda (a b)
+     (and ((comparator-equality-predicate car-comparator) (car a) (car b))
+          ((comparator-equality-predicate cdr-comparator) (cdr a) (cdr b)))))
+
+(define (make-pair<? car-comparator cdr-comparator)
+   (lambda (a b)
+      (if (=? car-comparator (car a) (car b))
+        (<? cdr-comparator (cdr a) (cdr b))
+        (<? car-comparator (car a) (car b)))))
+
+(define (make-pair-hash car-comparator cdr-comparator)
+   (lambda (obj)
+     (let ((acc (make-hasher)))
+       (acc (comparator-hash car-comparator (car obj)))
+       (acc (comparator-hash cdr-comparator (cdr obj)))
+       (acc))))
+
+;;; List comparator
+
+;; Cheap test for listness
+(define (norp? obj) (or (null? obj) (pair? obj)))
+
+(define (make-list-comparator element-comparator type-test empty? head tail)
+   (make-comparator
+     (make-list-type-test element-comparator type-test empty? head tail)
+     (make-list=? element-comparator type-test empty? head tail)
+     (make-list<? element-comparator type-test empty? head tail)
+     (make-list-hash element-comparator type-test empty? head tail)))
+
+
+(define (make-list-type-test element-comparator type-test empty? head tail)
+  (lambda (obj)
+    (and
+      (type-test obj)
+      (let ((elem-type-test (comparator-type-test-predicate element-comparator)))
+        (let loop ((obj obj))
+          (cond
+            ((empty? obj) #t)
+            ((not (elem-type-test (head obj))) #f)
+            (else (loop (tail obj)))))))))
+
+(define (make-list=? element-comparator type-test empty? head tail)
+  (lambda (a b)
+    (let ((elem=? (comparator-equality-predicate element-comparator)))
+      (let loop ((a a) (b b))
+        (cond
+          ((and (empty? a) (empty? b) #t))
+          ((empty? a) #f)
+          ((empty? b) #f)
+          ((elem=? (head a) (head b)) (loop (tail a) (tail b)))
+          (else #f))))))
+
+(define (make-list<? element-comparator type-test empty? head tail)
+  (lambda (a b)
+    (let ((elem=? (comparator-equality-predicate element-comparator))
+          (elem<? (comparator-ordering-predicate element-comparator)))
+      (let loop ((a a) (b b))
+        (cond
+          ((and (empty? a) (empty? b) #f))
+          ((empty? a) #t)
+          ((empty? b) #f)
+          ((elem=? (head a) (head b)) (loop (tail a) (tail b)))
+          ((elem<? (head a) (head b)) #t)
+          (else #f))))))
+
+(define (make-list-hash element-comparator type-test empty? head tail)
+  (lambda (obj)
+    (let ((elem-hash (comparator-hash-function element-comparator))
+          (acc (make-hasher)))
+      (let loop ((obj obj))
+        (cond
+          ((empty? obj) (acc))
+          (else (acc (elem-hash (head obj))) (loop (tail obj))))))))
+
+
+;;; Vector comparator
+
+(define (make-vector-comparator element-comparator type-test length ref)
+     (make-comparator
+       (make-vector-type-test element-comparator type-test length ref)
+       (make-vector=? element-comparator type-test length ref)
+       (make-vector<? element-comparator type-test length ref)
+       (make-vector-hash element-comparator type-test length ref)))
+
+(define (make-vector-type-test element-comparator type-test length ref)
+  (lambda (obj)
+    (and
+      (type-test obj)
+      (let ((elem-type-test (comparator-type-test-predicate element-comparator))
+            (len (length obj)))
+        (let loop ((n 0))
+          (cond
+            ((= n len) #t)
+            ((not (elem-type-test (ref obj n))) #f)
+            (else (loop (+ n 1)))))))))
+
+(define (make-vector=? element-comparator type-test length ref)
+   (lambda (a b)
+     (and
+       (= (length a) (length b))
+       (let ((elem=? (comparator-equality-predicate element-comparator))
+             (len (length b)))
+         (let loop ((n 0))
+           (cond
+             ((= n len) #t)
+             ((elem=? (ref a n) (ref b n)) (loop (+ n 1)))
+             (else #f)))))))
+
+(define (make-vector<? element-comparator type-test length ref)
+   (lambda (a b)
+     (cond
+       ((< (length a) (length b)) #t)
+       ((> (length a) (length b)) #f)
+        (else
+         (let ((elem=? (comparator-equality-predicate element-comparator))
+             (elem<? (comparator-ordering-predicate element-comparator))
+             (len (length a)))
+         (let loop ((n 0))
+           (cond
+             ((= n len) #f)
+             ((elem=? (ref a n) (ref b n)) (loop (+ n 1)))
+             ((elem<? (ref a n) (ref b n)) #t)
+             (else #f))))))))
+
+(define (make-vector-hash element-comparator type-test length ref)
+  (lambda (obj)
+    (let ((elem-hash (comparator-hash-function element-comparator))
+          (acc (make-hasher))
+          (len (length obj)))
+      (let loop ((n 0))
+        (cond
+          ((= n len) (acc))
+          (else (acc (elem-hash (ref obj n))) (loop (+ n 1))))))))
+
+(define (string-hash obj)
+  (let ((acc (make-hasher))
+        (len (string-length obj)))
+    (let loop ((n 0))
+      (cond
+        ((= n len) (acc))
+        (else (acc (char->integer (string-ref obj n))) (loop (+ n 1)))))))
+