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// RUN: %dafny /compile:3 /spillTargetCode:2 /compileTarget:cs "%s" > "%t"
// RUN: %dafny /compile:3 /spillTargetCode:2 /compileTarget:js "%s" >> "%t"
// RUN: %dafny /compile:3 /spillTargetCode:2 /compileTarget:go "%s" >> "%t"
// RUN: %diff "%s.expect" "%t"
method Main() {
AssignSuchThat();
LetSuchThat();
Quantifier();
MapComprehension();
OutParamsUnderLambdas(); // white-box testing
AltControlFlow();
}
predicate method Thirteen(x: int) { x == 13 }
predicate method Even(y: int) { y % 2 == 1 }
function method FourMore(x: int): int { x + 4 }
method AssignSuchThat() {
var x, y;
assert Thirteen(13);
x, y :| 12 <= x < y && Thirteen(x);
print "x=", x, " y=", y, "\n";
var b;
x, b, y :| 12 <= x < y && Thirteen(x) && b;
print "x=", x, " y=", y, " b=", if b then "yes" else "no", "\n";
}
method LetSuchThat() {
assert Thirteen(13);
var p := var x, y :| 12 <= x < y < 15 && Thirteen(x); (x, y);
print "p=", p, "\n";
var q := var x, b, y :| 12 <= x < y < 15 && Thirteen(x) && b; (x, y, if b then "yes" else "no");
print "q=", q, "\n";
}
method Quantifier() {
var s := [0, 1, 1, 2, 3, 5, 8, 13];
print forall x :: x in s ==> x < 20, " "; // true
print forall x :: x in s ==> x < 10, "\n"; // false
print exists x :: x in s && x == 3, " "; // true
print exists x :: x in s && x == 4, "\n"; // false
}
method MapComprehension() {
// var m := map x,y | 12 <= x < y < 17 && Thirteen(x) && Even(y) :: x := y;
var m := map x | 12 <= x < 15 :: x / 2;
print m, "\n";
m := map x | 12 <= x < 15 :: FourMore(x) := x;
print m, "\n";
}
method OutParamsUnderLambdas() {
var x, b := XP();
print "XP returned: ", x, " ", b, "\n";
var m := XM();
print "XM returned: ", m, "\n";
}
method XP() returns (x: int, b: bool) {
var s := {2, 4};
b := exists y :: y in s && y < x;
}
method XM() returns (x: int) {
var before, after;
var f := () => x;
before := f();
x := 2;
after := f();
print "after: ", f(), " ", "before: ", f(), "\n";
f := () => x;
before := f();
x := 16;
after := f();
print "after: ", f(), " ", "before: ", f(), "\n";
}
method AltControlFlow() {
var s := [2, 29, 34, 35, 36, 59, 104, 106, 107, 107, 108, 2700];
var lo, hi, Lo, Hi;
lo, hi := FindRange(s, 0, 3000);
Lo, Hi := FindRange(s, 35, 107);
print lo, " ", hi, " ", Lo, " ", Hi, "\n";
lo, hi := FindRangeIf(s, 0, 3000);
Lo, Hi := FindRangeIf(s, 35, 107);
print lo, " ", hi, " ", Lo, " ", Hi, "\n";
lo, hi := FindRangeBindingGuard(s, 0, 3000);
Lo, Hi := FindRangeBindingGuard(s, 35, 107);
print lo, " ", hi, " ", Lo, " ", Hi, "\n";
lo, hi := FindRangeBindingGuardAlt(s, 0, 3000);
Lo, Hi := FindRangeBindingGuardAlt(s, 35, 107);
print lo, " ", hi, " ", Lo, " ", Hi, "\n";
}
method FindRange(s: seq<int>, from: int, to: int) returns (lo: int, hi: int)
requires forall i,j :: 0 <= i < j < |s| ==> s[i] <= s[j]
requires from <= to
ensures 0 <= lo <= hi <= |s|
ensures forall i :: 0 <= i < |s| ==> (from <= s[i] < to <==> lo <= i < hi)
{
lo, hi := 0, |s|;
while
invariant lo <= hi <= |s|
invariant forall i :: 0 <= i < lo ==> s[i] < from
invariant forall i :: hi <= i < |s| ==> to <= s[i]
decreases hi - lo
{
case lo < |s| && s[lo] < from =>
lo := lo + 1;
case 0 < hi && to <= s[hi-1] =>
hi := hi - 1;
}
}
method FindRangeIf(s: seq<int>, from: int, to: int) returns (lo: int, hi: int)
requires forall i,j :: 0 <= i < j < |s| ==> s[i] <= s[j]
requires from <= to
ensures 0 <= lo <= hi <= |s|
ensures forall i :: 0 <= i < |s| ==> (from <= s[i] < to <==> lo <= i < hi)
{
lo, hi := 0, |s|;
while lo < hi
invariant lo <= hi <= |s|
invariant forall i :: 0 <= i < lo ==> s[i] < from
invariant forall i :: hi <= i < |s| ==> to <= s[i]
decreases hi - lo
{
if
case s[lo] < from =>
lo := lo + 1;
case to <= s[hi-1] =>
hi := hi - 1;
case from <= s[lo] && s[hi-1] < to =>
break;
}
}
method FindRangeBindingGuard(s: seq<int>, from: int, to: int) returns (lo: int, hi: int)
requires forall i,j :: 0 <= i < j < |s| ==> s[i] <= s[j]
requires from <= to
ensures 0 <= lo <= hi <= |s|
ensures forall i :: 0 <= i < |s| ==> (from <= s[i] < to <==> lo <= i < hi)
{
lo, hi := 0, |s|;
while lo < hi
invariant lo <= hi <= |s|
invariant forall i :: 0 <= i < lo ==> s[i] < from
invariant forall i :: hi <= i < |s| ==> to <= s[i]
decreases hi - lo
{
if j :| lo <= j < |s| && s[j] < from {
lo := j + 1;
} else if j :| 0 <= j < hi && to <= s[j] {
hi := j;
} else {
break;
}
}
}
method FindRangeBindingGuardAlt(s: seq<int>, from: int, to: int) returns (lo: int, hi: int)
requires forall i,j :: 0 <= i < j < |s| ==> s[i] <= s[j]
requires from <= to
ensures 0 <= lo <= hi <= |s|
ensures forall i :: 0 <= i < |s| ==> (from <= s[i] < to <==> lo <= i < hi)
{
lo, hi := 0, |s|;
while lo < hi
invariant lo <= hi <= |s|
invariant forall i :: 0 <= i < lo ==> s[i] < from
invariant forall i :: hi <= i < |s| ==> to <= s[i]
decreases hi - lo
{
if
case j :| lo <= j < |s| && s[j] < from =>
lo := j + 1;
case j :| 0 <= j < hi && to <= s[j] =>
hi := j;
case forall j :: lo <= j < hi ==> from <= s[j] < to =>
break;
}
}
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