initial commit
This commit is contained in:
commit
b088e7ba55
2
.gitignore
vendored
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2
.gitignore
vendored
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/zig-cache/
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/zig-out/
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71
build.zig
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71
build.zig
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const std = @import("std");
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// Although this function looks imperative, note that its job is to
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// declaratively construct a build graph that will be executed by an external
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// runner.
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pub fn build(b: *std.Build) void {
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// Standard target options allows the person running `zig build` to choose
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// what target to build for. Here we do not override the defaults, which
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// means any target is allowed, and the default is native. Other options
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// for restricting supported target set are available.
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const target = b.standardTargetOptions(.{});
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// Standard optimization options allow the person running `zig build` to select
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// between Debug, ReleaseSafe, ReleaseFast, and ReleaseSmall. Here we do not
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// set a preferred release mode, allowing the user to decide how to optimize.
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const optimize = b.standardOptimizeOption(.{});
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const exe = b.addExecutable(.{
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.name = "datastructures",
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// In this case the main source file is merely a path, however, in more
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// complicated build scripts, this could be a generated file.
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.root_source_file = .{ .path = "src/main.zig" },
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.target = target,
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.optimize = optimize,
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});
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exe.linkLibC();
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// This declares intent for the executable to be installed into the
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// standard location when the user invokes the "install" step (the default
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// step when running `zig build`).
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exe.install();
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// This *creates* a RunStep in the build graph, to be executed when another
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// step is evaluated that depends on it. The next line below will establish
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// such a dependency.
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const run_cmd = exe.run();
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// By making the run step depend on the install step, it will be run from the
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// installation directory rather than directly from within the cache directory.
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// This is not necessary, however, if the application depends on other installed
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// files, this ensures they will be present and in the expected location.
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run_cmd.step.dependOn(b.getInstallStep());
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// This allows the user to pass arguments to the application in the build
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// command itself, like this: `zig build run -- arg1 arg2 etc`
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if (b.args) |args| {
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run_cmd.addArgs(args);
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}
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// This creates a build step. It will be visible in the `zig build --help` menu,
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// and can be selected like this: `zig build run`
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// This will evaluate the `run` step rather than the default, which is "install".
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const run_step = b.step("run", "Run the app");
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run_step.dependOn(&run_cmd.step);
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// Creates a step for unit testing.
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const exe_tests = b.addTest(.{
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.root_source_file = .{ .path = "src/main.zig" },
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.target = target,
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.optimize = optimize,
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});
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exe_tests.linkLibC();
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// Similar to creating the run step earlier, this exposes a `test` step to
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// the `zig build --help` menu, providing a way for the user to request
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// running the unit tests.
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const test_step = b.step("test", "Run unit tests");
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test_step.dependOn(&exe_tests.step);
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}
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306
src/main.zig
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306
src/main.zig
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@ -0,0 +1,306 @@
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const std = @import("std");
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const BTree = struct {
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const Self = @This();
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const B: usize = 3;
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const CAPACITY: usize = 2 * B - 1;
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const NUM_EDGES: usize = 2 * B;
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ally: std.mem.Allocator = std.heap.c_allocator,
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root: ?NodeOrLeaf,
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fn create(ally: std.mem.Allocator) Self {
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return Self{
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.ally = ally,
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.root = null,
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};
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}
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fn insert(self: *Self, value: u32) !void {
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if (self.root) |*root| {
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switch (root.*) {
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.internal => |node| {
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std.debug.print("can't insert values into {?} yet :|\n", .{node});
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},
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.leaf => |leaf| {
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try leaf.insert_value(value);
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},
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}
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} else {
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var leaf: *Leaf = try self.ally.create(Leaf);
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errdefer self.ally.destroy(leaf);
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leaf.init(self.ally);
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try leaf.insert_value(value);
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self.root = NodeOrLeaf{ .leaf = leaf };
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}
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}
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fn destroy(self: *Self) void {
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if (self.root) |*root| {
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root.destroy();
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}
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}
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const NodeOrLeafTag = enum {
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internal,
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leaf,
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};
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const NodeOrLeaf = union(NodeOrLeafTag) {
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internal: *Node,
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leaf: *Leaf,
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fn destroy(self: *NodeOrLeaf) void {
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self.as_leaf().destroy();
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}
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fn as_leaf(self: *NodeOrLeaf) *Leaf {
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switch (self.*) {
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.internal => |node| {
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return node.as_leaf();
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},
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.leaf => |leaf| {
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return leaf;
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},
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}
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}
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fn from_leaf(leaf: *Leaf) NodeOrLeaf {
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if (leaf.level == 0) {
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return .{ .leaf = leaf };
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} else {
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return .{ .node = @ptrCast(Node, leaf) };
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}
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}
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};
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const Node = struct {
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leaf: Leaf,
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edges: [NUM_EDGES]?NodeOrLeaf = undefined,
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fn create(ally: std.mem.Allocator) !Leaf {
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var node = try ally.create(Node);
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node.init(ally);
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return node;
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}
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fn init(self: *Leaf, ally: std.mem.Allocator) void {
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self.* = Node{ .leaf = Leaf{ .ally = ally } };
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}
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fn as_leaf(self: *Node) *Leaf {
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return &self.leaf;
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}
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fn insert_node(self: *Node, child: NodeOrLeaf) void {
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const self_leaf = self.as_leaf();
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const ls = child.as_leaf().get_values()[0];
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var idx: u16 = 0;
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for (self_leaf.get_values(), 0..) |v, i| {
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idx = @intCast(u16, i);
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if (v > ls) {
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break;
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}
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}
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if (self.get_edges()[idx]) |edge| {
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std.debug.print("edge already present?: {?}", .{edge});
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} else {
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child.as_leaf().parent = .{ .parent = self, .idx = idx };
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self.get_edges()[idx] = child;
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}
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}
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fn get_edges(self: *Node) []?NodeOrLeaf {
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const len = self.leaf.len;
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return self.edges[0..len];
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}
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};
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const ParentPtr = struct {
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parent: *Node,
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idx: u16,
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};
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const Leaf = struct {
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ally: std.mem.Allocator,
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level: usize = 0,
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parent: ?ParentPtr = null,
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len: u16 = 0,
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values: [CAPACITY]u32 = undefined,
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fn create(ally: std.mem.Allocator) !*Leaf {
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var leaf = try ally.create(Leaf);
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leaf.init(ally);
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return leaf;
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}
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fn init(self: *Leaf, ally: std.mem.Allocator) void {
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self.* = Leaf{ .ally = ally };
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}
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fn destroy(self: *Leaf) void {
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self.ally.destroy(self);
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}
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fn push_value(self: *Leaf, value: u32) void {
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std.debug.assert(self.len < CAPACITY);
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var tmp = value;
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for (self.get_values()) |*val| {
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if (val.* < value) {
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continue;
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}
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const t = val.*;
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val.* = tmp;
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tmp = t;
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}
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self.values[self.len] = tmp;
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self.len = self.len + 1;
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}
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const SplitResult = struct {
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// attached
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left: *Leaf,
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// lose value, previously attacked, must be inserted
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middle: u32,
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// free floating leaf, must be attached
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right: *Leaf,
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};
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fn split_at(self: *Leaf, value: u32) !SplitResult {
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var idx: u16 = 0;
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for (self.get_values(), 0..) |v, i| {
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idx = @intCast(u16, i);
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if (v > value) {
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break;
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}
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}
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std.debug.assert(idx > 0 and idx < CAPACITY - 1);
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var new = try Leaf.create(self.ally);
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new.level = self.level;
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var middle: u32 = undefined;
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// take from right half
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if (idx > B) {
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new.len = self.len - (idx + 1);
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std.mem.copy(u32, &new.values, self.values[(idx + 1)..self.len]);
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middle = self.values[idx];
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self.len = idx;
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self.push_value(value);
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} else {
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// take from left half
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new.len = self.len - (idx);
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std.mem.copy(u32, &new.values, self.values[idx..self.len]);
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new.push_value(value);
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middle = self.values[idx - 1];
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self.len = idx - 1;
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}
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return .{ .left = self, .middle = middle, .right = new };
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}
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fn insert_value(self: *Leaf, value: u32) !void {
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if (self.len < CAPACITY) {
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self.push_value(value);
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} else {
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return error.LeafAtCapacity;
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}
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}
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fn get_values(self: *Leaf) []u32 {
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const len = self.len;
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return self.values[0..len];
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}
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};
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};
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pub fn main() !void {
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// Prints to stderr (it's a shortcut based on `std.io.getStdErr()`)
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std.debug.print("All your {s} are belong to us.\n", .{"codebase"});
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// stdout is for the actual output of your application, for example if you
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// are implementing gzip, then only the compressed bytes should be sent to
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// stdout, not any debugging messages.
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const stdout_file = std.io.getStdOut().writer();
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var bw = std.io.bufferedWriter(stdout_file);
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const stdout = bw.writer();
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try stdout.print("Run `zig build test` to run the tests.\n", .{});
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try bw.flush(); // don't forget to flush!
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}
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test "btree leaf" {
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std.testing.refAllDeclsRecursive(BTree);
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std.testing.refAllDeclsRecursive(BTree.Leaf);
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var leaf = BTree.Leaf{ .ally = std.testing.allocator, .parent = null, .len = 2, .values = [_]u32{ 5, 6, undefined, undefined, undefined } };
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const values = leaf.get_values();
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std.debug.print("{?}\n", .{leaf});
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std.debug.print("{any}\n", .{values});
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}
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fn printValues(leaf: *BTree.Leaf) void {
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const values = leaf.get_values();
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std.debug.print("{any}\n", .{values});
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}
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test "leaf split" {
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std.debug.print("testing splitting\n", .{});
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var tree = BTree.create(std.testing.allocator);
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defer tree.destroy();
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try tree.insert(2);
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try tree.insert(4);
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try tree.insert(6);
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try tree.insert(3);
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try tree.insert(7);
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std.debug.print("before split:", .{});
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printValues(tree.root.?.as_leaf());
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const split = try tree.root.?.as_leaf().split_at(5);
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std.debug.print("after split:", .{});
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printValues(tree.root.?.as_leaf());
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std.debug.print("split: {?}\n", .{split});
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tree.ally.destroy(split.right);
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}
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test "btree new" {
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std.debug.print("testing insertion\n", .{});
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var tree = BTree.create(std.testing.allocator);
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defer tree.destroy();
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try tree.insert(5);
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printValues(tree.root.?.as_leaf());
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try tree.insert(4);
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printValues(tree.root.?.as_leaf());
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try tree.insert(6);
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printValues(tree.root.?.as_leaf());
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try tree.insert(3);
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printValues(tree.root.?.as_leaf());
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try tree.insert(7);
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printValues(tree.root.?.as_leaf());
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//try tree.insert(8);
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}
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test "simple test" {
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var list = std.ArrayList(i32).init(std.testing.allocator);
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defer list.deinit(); // try commenting this out and see if zig detects the memory leak!
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try list.append(42);
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try std.testing.expectEqual(@as(i32, 42), list.pop());
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}
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