From bcaa281e6c6569452a798034c37da7e0d6a047a7 Mon Sep 17 00:00:00 2001
From: Enrico Lumetti <enrico.lumetti@gmail.com>
Date: Sat, 1 May 2021 00:06:37 +0200
Subject: [PATCH] Implement and test explicate-control

---
 explicate-control.scm      | 32 +++++++++++++++++++++
 test-explicate-control.scm | 59 ++++++++++++++++++++++++++++++++++++++
 2 files changed, 91 insertions(+)
 create mode 100644 explicate-control.scm
 create mode 100644 test-explicate-control.scm

diff --git a/explicate-control.scm b/explicate-control.scm
new file mode 100644
index 0000000..8efbc43
--- /dev/null
+++ b/explicate-control.scm
@@ -0,0 +1,32 @@
+#lang racket
+
+(require racket/fixnum)
+
+(provide explicate-control)
+
+(define (explicate-control sexp)
+  (match sexp
+    [`(program ,info ,exp)
+      `(program ,info ,(explicate-control-tail exp))]))
+
+; after a remove-complex-opera*, all expressions
+; are compatible with C0
+(define (explicate-control-tail exp)
+  (match exp
+    [(? fixnum?) `(return ,exp)]
+    [(? symbol?) `(return ,exp)]
+    [`(read) `(return ,exp)]
+    [`(- ,e) `(return ,exp)]
+    [`(+ ,e1 ,e2) `(return ,exp)]
+    [`(let ([,var ,rexp]) ,body)
+     (explicate-control-assign var rexp (explicate-control-tail body))]))
+
+; stmt :=  (assign var exp)
+; tail :=  (return exp) / (seq stmt tail)
+(define (explicate-control-assign var exp c0-body) `()
+  (match exp
+     [`(let ([,v ,x]) ,b) (explicate-control-assign v x (explicate-control-assign var b c0-body))]
+     [_ `(seq (assign ,var ,exp) ,c0-body)]))
+
+
+
diff --git a/test-explicate-control.scm b/test-explicate-control.scm
new file mode 100644
index 0000000..1fc4636
--- /dev/null
+++ b/test-explicate-control.scm
@@ -0,0 +1,59 @@
+#lang racket
+
+(require "test-util.scm")
+(require "remove-complex-oper.scm")
+(require "explicate-control.scm")
+(require "c2.scm")
+
+(define programs 
+  (list
+   `(program () (+ 2 3))
+   `(program () (+ (- 2) 3))
+   `(program ()
+             (let ([y (let ([x 20])
+                        (+ x (let ([x 22]) x)))]) y))
+   `(program ()
+      (let ([a 42])
+        (let ([b a])
+          b)))
+
+   `(program () (+ (let ([x (+ (- 1) 2)]) (+ x 2)) (+ 4 5)))))
+
+      
+
+(define (pass program) (explicate-control (remove-complex-opera* program)))
+
+(test-eq
+ (pass (list-ref programs 0))
+ `(program ()
+           (return (+ 2 3))))
+
+(test-eq
+ (pass (list-ref programs 1))
+ `(program ()
+           (seq (assign tmp.1 (- 2))
+             (return (+ tmp.1 3)))))
+
+(test-eq
+  (pass (list-ref programs 2))
+  `(program ()
+     (seq (assign x.1 20)
+      (seq (assign x.2 22)
+       (seq (assign y.1 (+ x.1 x.2))
+        (return y.1))))))
+
+(test-eq
+ (pass (list-ref programs 3))
+ `(program ()
+           (seq (assign a.1 42)
+                (seq (assign b.1 a.1)
+                     (return b.1)))))
+
+(test-eq
+ (pass (list-ref programs 4))
+ `(program ()
+           (seq (assign tmp.1 (- 1)) 
+                (seq (assign x.1 (+ tmp.1 2)) 
+                     (seq (assign tmp.2 (+ x.1 2)) 
+                          (seq (assign tmp.3 (+ 4 5)) 
+                               (return (+ tmp.2 tmp.3))))))))