Add Math::BigInt.Bool and infix:<**>.

colomon · Jan 30, 2011 · 5627557 · 5627557
1 parent 286b859
commit 5627557
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Showing 3 changed files with 37 additions and 2 deletions.
diff --git a/lib/Math/BigInt.pm b/lib/Math/BigInt.pm
@@ -13,6 +13,7 @@ sub bdModulo(OpaquePointer $w, OpaquePointer $u, OpaquePointer $v) returns Int i
 sub bdConvToDecimal(OpaquePointer $bd, OpaquePointer $s, Int $smax) returns Int is native("libbd") { ... }
 sub bdIsEqual(OpaquePointer $a, OpaquePointer $b) returns Int is native("libbd") { ... }
 sub bdCompare(OpaquePointer $a, OpaquePointer $b) returns Int is native("libbd") { ... }
+sub bdIsZero(OpaquePointer $a) returns Int is native("libbd") { ... }
 
 sub malloc(Int $n) returns OpaquePointer is native("libSystem") { ... }
 sub free(OpaquePointer $p) is native("libSystem") { ... }
@@ -46,8 +47,12 @@ class Math::BigInt does Real {
         $result;
     }
 
-    method Bridge() {
-        +self.Str;
+    method Bridge(Math::BigInt $x:) {
+        +$x.Str;
+    }
+
+    method Bool(Math::BigInt $x:) {
+        !bdIsZero($x.bd);
     }
 
     method succ(Math::BigInt $x:) { bdIncrement($x.bd); self; }
@@ -140,6 +145,24 @@ class Math::BigInt does Real {
         bdModulo($result.bd, $a.bd, Math::BigInt.new($b).bd);
         $result.Int;
     }
+
+    multi sub infix:<**>(Math::BigInt $a, Math::BigInt $b is copy) is export(:DEFAULT) {
+        my $result = Math::BigInt.new("1");
+        my $power = $a;
+        loop {
+            my $r = $b % 2;
+            if $r {
+                $result = $result * $power;
+            }
+            $b = ($b - $r) div 2;
+            last unless $b;
+        }
+        $result;
+    }
+
+    multi sub infix:<**>(Math::BigInt $a, Int $b) is export(:DEFAULT) {
+        $a ** Math::BigInt.new($b);
+    }
 
     # Comparison operators
 

diff --git a/t/01-basic.t b/t/01-basic.t
@@ -29,13 +29,15 @@ plan *;
     is +$b, 22, ".succ works";
     $a = $b.pred;
     is +$a, 21, ".pred works";
+    ok $a.Bool, "and 21.Bool is true";
 
     $a++;
     is +$a, 22, "Increment works";
     isa_ok $a, Math::BigInt, "It's still a BigInt";
     $a--;
     is +$a, 21, "Decrement works";
     isa_ok $a, Math::BigInt, "It's still a BigInt";
+    nok ($a - $a).Bool, "0 is false";
 }
 
 done;
diff --git a/t/02-arith.t b/t/02-arith.t
@@ -121,6 +121,16 @@ plan *;
     is $c, 1, "and it's 1";
 }
 
+# power!
+{
+    my @powers-of-three := Math::BigInt.new(1), * * 3 ... *;
+    for ^20 -> $i {
+        is @powers-of-three[$i], 3¹ ** $i, "3 ** $i agrees (integer power)";
+        is @powers-of-three[$i], 3¹ ** Math::BigInt.new($i), "3 ** $i agrees (Math::BigInt power)";
+    }
+}
+
+