shithub: mc

Download patch

ref: aa906e108823e155dd2c5e9b1b4ef6967f55473b
parent: 4855e100dd14214ffe838fd836e4dcb726dea1d2
author: Ori Bernstein <ori@eigenstate.org>
date: Sun Sep 4 16:50:27 EDT 2016 

Add byreverse iterator.


--- a/lib/std/iterutil.myr
+++ b/lib/std/iterutil.myr
@@ -7,6 +7,11 @@
 		s2	: @b[:]
 	;;
 
+	type reverseiter(@a) = struct
+		sl	: @a[:]
+		idx	: size
+	;;
+
 	type enumiter(@a) = struct
 		idx	: size
 		s	: @a[:]
@@ -14,9 +19,11 @@
 
 	impl iterable zipiter(@a, @b) -> (@a, @b)
 	impl iterable enumiter(@a) -> (size, @a)
+	impl iterable reverseiter(@a) -> (size, @a)
 
 	generic byzip	: (a : @a[:], b : @b[:]	 -> zipiter(@a, @b))
 	generic byenum	: (a : @a[:] -> enumiter(@a))
+	generic byreverse 	: (sl : @a[:] -> reverseiter(@a))
 ;;
 
 generic byzip = {a, b
@@ -39,7 +46,25 @@
 	}
 ;;
 
+generic byreverse = {sl
+	-> [.sl = sl, .idx = sl.len]
+}
 
+impl iterable reverseiter(@a) -> @a =
+	__iternext__ = {itp, valp
+		if itp.idx > 0
+			valp# = itp.sl[itp.idx - 1]
+			itp.idx--
+			-> true
+		else
+			-> false
+		;;
+	}
+
+	__iterfin__ = {itp, valp
+	}
+;;
+
 generic byenum = {a
 	-> [.s = a, .idx = 0]
 }
@@ -47,7 +72,6 @@
 impl iterable enumiter(@a) -> (size, @b) =
 	__iternext__ = {itp, valp
 		if itp.idx < itp.s.len
-			std.put("itp.idx: {}, itp.s[{}]: {}\n", itp.idx, itp.idx, itp.s[itp.idx])
 			valp# = (itp.idx, itp.s[itp.idx])
 			itp.idx++
 			-> true
--- a/lib/std/test/iterutil.myr
+++ b/lib/std/test/iterutil.myr
@@ -16,4 +16,11 @@
 		std.assert(b == n*2 + 2, "invalid val from b: {}", b)
 		n++
 	;;
+
+	n = 0
+	for x in std.byreverse([3, 2, 1, 0][:])
+		std.assert(x == n, "invalid reversed value {}, expected {}", x, n)
+		n++
+	;;
+
 }