mirror/zig
1
0
Fork 0
mirror of https://github.com/ziglang/zig.git synced 2026-02-18 23:39:17 +00:00
Code Issues Packages Projects Releases Wiki Activity

rb: add sort() that re-sorts tree with new compare function

Browse Source 
You can also specify the same compare function, but after updating the
context that the function will use (connected to the rb.Tree) before.
This commit is contained in:
Shawn Landden 2020-01-19 22:10:21 +04:00
parent e190082922
commit 4ab9678b95
1 changed files with 23 additions and 0 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

23
lib/std/rb.zig
View File

@ -134,6 +134,20 @@ pub const Tree = struct {
root: ?*Node,
compareFn: fn (*Node, *Node, *Tree) Order,
/// Re-sorts a tree with a new compare function
pub fn sort(tree: *Tree, newCompareFn: fn (*Node, *Node, *Tree) Order) !void {
var newTree = Tree.init(newCompareFn);
var node: *Node = undefined;
while (true) {
node = tree.first() orelse break;
tree.remove(node);
if (newTree.insert(node) != null) {
return error.NotUnique; // EEXISTS
}
}
tree.* = newTree;
}
/// If you have a need for a version that caches this, please file a bug.
pub fn first(tree: *Tree) ?*Node {
var node: *Node = tree.root orelse return null;
@ -244,6 +258,7 @@ pub const Tree = struct {
return doLookup(key, tree, &parent, &is_left);
}
/// If node is not part of tree, behavior is undefined.
pub fn remove(tree: *Tree, nodeconst: *Node) void {
var node = nodeconst;
// as this has the same value as node, it is unsafe to access node after newnode
@ -514,6 +529,10 @@ fn testCompare(l: *Node, r: *Node, contextIgnored: *Tree) Order {
unreachable;
}
fn testCompareReverse(l: *Node, r: *Node, contextIgnored: *Tree) Order {
return testCompare(r, l, contextIgnored);
}
test "rb" {
if (@import("builtin").arch == .aarch64) {
// TODO https://github.com/ziglang/zig/issues/3288
@ -600,4 +619,8 @@ test "multiple inserts, followed by calling first and last" {
var lookupNode: testNumber = undefined;
lookupNode.value = 3;
assert(tree.lookup(&lookupNode.node) == &third.node);
tree.sort(testCompareReverse) catch unreachable;
assert(testGetNumber(tree.first().?).value == 3);
assert(testGetNumber(tree.last().?).value == 0);
assert(tree.lookup(&lookupNode.node) == &third.node);
}