authorgravatar for thatlemon@gmail.comLemonBoy <thatlemon@gmail.com> 2020-02-03 14:42:32+01:00
committergravatar for thatlemon@gmail.comLemonBoy <thatlemon@gmail.com> 2020-02-03 21:51:03+01:00
logdb3aea3a0bfce6af04d941003c6a63e86cfdee1a
treeecadf721e422cc48bcaf4da578f0e1885efb4527
parentfd8d8afb243d5a6ceadaf38ad08b72be915fce2e

Change API for binarySearch fn

1 files changed, 17 insertions(+), 18 deletions(-)

lib/std/sort.zig+17-18
...@@ -5,7 +5,7 @@ const mem = std.mem;...@@ -5,7 +5,7 @@ const mem = std.mem;
5const math = std.math;5const math = std.math;
6const builtin = @import("builtin");6const builtin = @import("builtin");
77
8pub fn binarySearch(comptime T: type, items: []T, comptime compareFn: fn (val: T) math.Order) ?usize {8pub fn binarySearch(comptime T: type, key: T, items: []const T, comptime compareFn: fn (lhs: T, rhs: T) math.Order) ?usize {
9 if (items.len < 1)9 if (items.len < 1)
10 return null;10 return null;
1111
...@@ -15,11 +15,11 @@ pub fn binarySearch(comptime T: type, items: []T, comptime compareFn: fn (val: T...@@ -15,11 +15,11 @@ pub fn binarySearch(comptime T: type, items: []T, comptime compareFn: fn (val: T
15 while (left <= right) {15 while (left <= right) {
16 // Avoid overflowing in the midpoint calculation16 // Avoid overflowing in the midpoint calculation
17 const mid = left + (right - left) / 2;17 const mid = left + (right - left) / 2;
18 // Compare the midpoint element with the key18 // Compare the key with the midpoint element
19 switch (compareFn(items[mid])) {19 switch (compareFn(key, items[mid])) {
20 .eq => return mid,20 .eq => return mid,
21 .lt => left = mid + 1,21 .gt => left = mid + 1,
22 .gt => right = mid - 1,22 .lt => right = mid - 1,
23 }23 }
24 }24 }
2525
...@@ -28,41 +28,40 @@ pub fn binarySearch(comptime T: type, items: []T, comptime compareFn: fn (val: T...@@ -28,41 +28,40 @@ pub fn binarySearch(comptime T: type, items: []T, comptime compareFn: fn (val: T
2828
29test "std.sort.binarySearch" {29test "std.sort.binarySearch" {
30 const S = struct {30 const S = struct {
31 fn makeComparisonPred(comptime T: type, value: T) type {31 fn order_u32(lhs: u32, rhs: u32) math.Order {
32 return struct {32 return math.order(lhs, rhs);
33 fn pred(v: T) math.Order {33 }
34 return math.order(v, value);34 fn order_i32(lhs: i32, rhs: i32) math.Order {
35 }35 return math.order(lhs, rhs);
36 };
37 }36 }
38 };37 };
39 testing.expectEqual(38 testing.expectEqual(
40 @as(?usize, null),39 @as(?usize, null),
41 binarySearch(u32, &[_]u32{}, S.makeComparisonPred(u32, 1).pred),40 binarySearch(u32, 1, &[_]u32{}, S.order_u32),
42 );41 );
43 testing.expectEqual(42 testing.expectEqual(
44 @as(?usize, 0),43 @as(?usize, 0),
45 binarySearch(u32, &[_]u32{1}, S.makeComparisonPred(u32, 1).pred),44 binarySearch(u32, 1, &[_]u32{1}, S.order_u32),
46 );45 );
47 testing.expectEqual(46 testing.expectEqual(
48 @as(?usize, null),47 @as(?usize, null),
49 binarySearch(u32, &[_]u32{0}, S.makeComparisonPred(u32, 1).pred),48 binarySearch(u32, 1, &[_]u32{0}, S.order_u32),
50 );49 );
51 testing.expectEqual(50 testing.expectEqual(
52 @as(?usize, 4),51 @as(?usize, 4),
53 binarySearch(u32, &[_]u32{ 1, 2, 3, 4, 5 }, S.makeComparisonPred(u32, 5).pred),52 binarySearch(u32, 5, &[_]u32{ 1, 2, 3, 4, 5 }, S.order_u32),
54 );53 );
55 testing.expectEqual(54 testing.expectEqual(
56 @as(?usize, 0),55 @as(?usize, 0),
57 binarySearch(u32, &[_]u32{ 2, 4, 8, 16, 32, 64 }, S.makeComparisonPred(u32, 2).pred),56 binarySearch(u32, 2, &[_]u32{ 2, 4, 8, 16, 32, 64 }, S.order_u32),
58 );57 );
59 testing.expectEqual(58 testing.expectEqual(
60 @as(?usize, 1),59 @as(?usize, 1),
61 binarySearch(i32, &[_]i32{ -7, -4, 0, 9, 10 }, S.makeComparisonPred(i32, -4).pred),60 binarySearch(i32, -4, &[_]i32{ -7, -4, 0, 9, 10 }, S.order_i32),
62 );61 );
63 testing.expectEqual(62 testing.expectEqual(
64 @as(?usize, 3),63 @as(?usize, 3),
65 binarySearch(i32, &[_]i32{ -100, -25, 2, 98, 99, 100 }, S.makeComparisonPred(i32, 98).pred),64 binarySearch(i32, 98, &[_]i32{ -100, -25, 2, 98, 99, 100 }, S.order_i32),
66 );65 );
67}66}
6867