Add .succ and .pred.

colomon · Jan 29, 2011 · 2cfe839 · 2cfe839
1 parent 6cc43b1
commit 2cfe839
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diff --git a/lib/Math/BigInt.pm b/lib/Math/BigInt.pm
@@ -3,6 +3,8 @@ use NativeCall;
 sub bdNew() returns OpaquePointer is native("libbd") { ... }
 sub bdFreeSol(OpaquePointer $bd) is native("libbd") { ... }
 sub bdConvFromDecimal(OpaquePointer $bd, Str $digits) returns Int is native("libbd") { ... }
+sub bdIncrement(OpaquePointer $w) returns Int is native("libbd") { ... }
+sub bdDecrement(OpaquePointer $w) returns Int is native("libbd") { ... }
 sub bdAdd(OpaquePointer $w, OpaquePointer $u, OpaquePointer $v) returns Int is native("libbd") { ... }
 sub bdSubtract(OpaquePointer $w, OpaquePointer $u, OpaquePointer $v) returns Int is native("libbd") { ... }
 sub bdMultiply(OpaquePointer $w, OpaquePointer $u, OpaquePointer $v) returns Int is native("libbd") { ... }
@@ -45,6 +47,9 @@ class Math::BigInt does Real {
         +self.Str;
     }
 
+    method succ(Math::BigInt $x:) { bdIncrement($x.bd); self; }
+    method pred(Math::BigInt $x:) { bdDecrement($x.bd); self; } 
+
     multi sub infix:<+>(Math::BigInt $a, Math::BigInt $b) is export(:DEFAULT) {
         my $result = Math::BigInt.new("1");
         bdAdd($result.bd, $a.bd, $b.bd);

diff --git a/t/01-basic.t b/t/01-basic.t
@@ -20,4 +20,22 @@ plan *;
     is_approx +$a, 1234567890098765432100123456789, "Numifies properly";
 }
 
+{
+    my $a = Math::BigInt.new("21");
+    isa_ok $a, Math::BigInt, "We successfully made a BigInt";
+    ok $a ~~ Numeric & Real, "It's Numeric and Real, too";
+    is +$a, 21, "Starts with proper value";
+    my $b = $a.succ;
+    is +$b, 22, ".succ works";
+    $a = $b.pred;
+    is +$a, 21, ".pred works";
+
+    $a++;
+    is +$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";
+}
+
 done;