From d5d21c858e194e789fc0298c3f4ea526f5f2bc46 Mon Sep 17 00:00:00 2001
From: Matthew Butterick <mb@mbtype.com>
Date: Thu, 2 Dec 2021 21:45:50 -0800
Subject: [PATCH] size and point

---
 quad/quad2/main.rkt | 73 +++++++++++++++++++++++----------------------
 1 file changed, 37 insertions(+), 36 deletions(-)

diff --git a/quad/quad2/main.rkt b/quad/quad2/main.rkt
index 098e141d..9f051ff6 100644
--- a/quad/quad2/main.rkt
+++ b/quad/quad2/main.rkt
@@ -1,20 +1,23 @@
 #lang debug racket/base
 (require racket/contract racket/function rackunit)
 
-(struct $posn (x y) #:transparent)
+(struct $point (x y) #:transparent #:mutable)
+(struct $size (width height) #:transparent #:mutable)
+(struct $rect (origin size) #:transparent #:mutable)
+
 (struct $quad (posn char) #:transparent #:mutable)
 
 (define/contract (posn-add p0 p1)
-  ($posn? $posn? . -> . $posn?)
-  ($posn (+ ($posn-x p0) ($posn-x p1)) (+ ($posn-y p0) ($posn-y p1))))
+  ($point? $size? . -> . $point?)
+  ($point (+ ($point-x p0) ($size-width p1)) (+ ($point-y p0) ($size-height p1))))
 
 (define/contract (size char)
-  ($quad? . -> . $posn?)
-  ($posn 1 1))
+  ($quad? . -> . $size?)
+  ($size 1 1))
 
 (define/contract (advance char)
-  ($quad? . -> . $posn?)
-  ($posn 1 0))
+  ($quad? . -> . $size?)
+  ($size 1 0))
 
 (define pass/c ((listof $quad?) . -> . (listof $quad?)))
 
@@ -41,38 +44,36 @@
       (error 'postcondition-failed))
     res))
 
-(struct $rect (x y width height) #:transparent #:mutable)
-
-(define (min-x rect) ($rect-x rect))
-(define (max-x rect) (+ (min-x rect) ($rect-width rect)))
-(define (min-y rect) ($rect-y rect))
-(define (max-y rect) (+ (min-y rect) ($rect-height rect)))
+(define (min-x rect) ($point-x ($rect-origin rect)))
+(define (width rect) ($size-width ($rect-size rect)))
+(define (max-x rect) (+ (min-x rect) (width rect)))
+(define (min-y rect) ($point-y ($rect-origin rect)))
+(define (height rect) ($size-height ($rect-size rect)))
+(define (max-y rect) (+ (min-y rect) (height rect)))
 
-(define/contract (rect-contains-posn? rect posn)
-  ($rect? $posn? . -> . boolean?)
-  (and (<= (min-x rect) ($posn-x posn) (max-x rect))
-       (<= (min-y rect) ($posn-y posn) (max-y rect))))
+(define/contract (rect-contains-point? rect pt)
+  ($rect? $point? . -> . boolean?)
+  (and (<= (min-x rect) ($point-x pt) (max-x rect))
+       (<= (min-y rect) ($point-y pt) (max-y rect))))
 
 (define/contract (rect-contains-rect? outer inner)
   ($rect? $rect? . -> . boolean?)
-  (and (rect-contains-posn? outer ($posn (min-x inner) (min-y inner)))
-       (rect-contains-posn? outer ($posn (max-x inner) (max-y inner)))))
+  (and (rect-contains-point? outer ($rect-origin inner))
+       (rect-contains-point? outer ($point (max-x inner) (max-y inner)))))
   
-
 (define (has-position? q) (not (eq? ($quad-posn q) #false)))
 (define-pass (layout qs)
   #:precondition (λ (qs) (andmap (λ (q) (not (has-position? q))) qs))
   #:postcondition (λ (qs) (andmap has-position? qs))
-  (define frame ($rect 0 0 5 30))
+  (define frame ($rect ($point 0 0) ($size 5 30)))
   (define (quad-fits? q posn)
     (define q-size (size q))
-    (define quad-rect ($rect ($posn-x posn) ($posn-y posn)
-                             ($posn-x q-size) ($posn-y q-size)))
+    (define quad-rect ($rect posn q-size))
     (and (rect-contains-rect? frame quad-rect) posn))
-  (for/fold ([posn ($posn 0 0)]
+  (for/fold ([posn ($point 0 0)]
              #:result qs)
             ([q (in-list qs)])
-    (define first-posn-on-next-line ($posn 0 (add1 ($posn-y posn))))
+    (define first-posn-on-next-line ($point 0 (add1 ($point-y posn))))
     (define winning-posn (or (ormap (λ (posn) (quad-fits? q posn)) (list posn first-posn-on-next-line)) (error 'no-posn-that-fits)))
     (set-$quad-posn! q winning-posn)
     (posn-add winning-posn (advance q))))
@@ -80,14 +81,14 @@
 (define compile (make-compiler layout))
 (check-equal? (compile "Hello world")
               (list
-               ($quad ($posn 0 0) #\H)
-               ($quad ($posn 1 0) #\e)
-               ($quad ($posn 2 0) #\l)
-               ($quad ($posn 3 0) #\l)
-               ($quad ($posn 4 0) #\o)
-               ($quad ($posn 0 1) #\space)
-               ($quad ($posn 1 1) #\w)
-               ($quad ($posn 2 1) #\o)
-               ($quad ($posn 3 1) #\r)
-               ($quad ($posn 4 1) #\l)
-               ($quad ($posn 0 2) #\d)))
\ No newline at end of file
+               ($quad ($point 0 0) #\H)
+               ($quad ($point 1 0) #\e)
+               ($quad ($point 2 0) #\l)
+               ($quad ($point 3 0) #\l)
+               ($quad ($point 4 0) #\o)
+               ($quad ($point 0 1) #\space)
+               ($quad ($point 1 1) #\w)
+               ($quad ($point 2 1) #\o)
+               ($quad ($point 3 1) #\r)
+               ($quad ($point 4 1) #\l)
+               ($quad ($point 0 2) #\d)))
\ No newline at end of file