zig/std/buf_map.zig

104 lines
3.1 KiB
Zig

const std = @import("std.zig");
const HashMap = std.HashMap;
const mem = std.mem;
const Allocator = mem.Allocator;
const testing = std.testing;
/// BufMap copies keys and values before they go into the map, and
/// frees them when they get removed.
pub const BufMap = struct {
hash_map: BufMapHashMap,
const BufMapHashMap = HashMap([]const u8, []const u8, mem.hash_slice_u8, mem.eql_slice_u8);
pub fn init(allocator: *Allocator) BufMap {
var self = BufMap{ .hash_map = BufMapHashMap.init(allocator) };
return self;
}
pub fn deinit(self: *BufMap) void {
var it = self.hash_map.iterator();
while (true) {
const entry = it.next() orelse break;
self.free(entry.key);
self.free(entry.value);
}
self.hash_map.deinit();
}
/// Same as `set` but the key and value become owned by the BufMap rather
/// than being copied.
/// If `setMove` fails, the ownership of key and value does not transfer.
pub fn setMove(self: *BufMap, key: []u8, value: []u8) !void {
const get_or_put = try self.hash_map.getOrPut(key);
if (get_or_put.found_existing) {
self.free(get_or_put.kv.key);
get_or_put.kv.key = key;
}
get_or_put.kv.value = value;
}
/// `key` and `value` are copied into the BufMap.
pub fn set(self: *BufMap, key: []const u8, value: []const u8) !void {
const value_copy = try self.copy(value);
errdefer self.free(value_copy);
// Avoid copying key if it already exists
const get_or_put = try self.hash_map.getOrPut(key);
if (!get_or_put.found_existing) {
get_or_put.kv.key = self.copy(key) catch |err| {
_ = self.hash_map.remove(key);
return err;
};
}
get_or_put.kv.value = value_copy;
}
pub fn get(self: BufMap, key: []const u8) ?[]const u8 {
const entry = self.hash_map.get(key) orelse return null;
return entry.value;
}
pub fn delete(self: *BufMap, key: []const u8) void {
const entry = self.hash_map.remove(key) orelse return;
self.free(entry.key);
self.free(entry.value);
}
pub fn count(self: BufMap) usize {
return self.hash_map.count();
}
pub fn iterator(self: *const BufMap) BufMapHashMap.Iterator {
return self.hash_map.iterator();
}
fn free(self: BufMap, value: []const u8) void {
self.hash_map.allocator.free(value);
}
fn copy(self: BufMap, value: []const u8) ![]u8 {
return mem.dupe(self.hash_map.allocator, u8, value);
}
};
test "BufMap" {
var bufmap = BufMap.init(std.heap.direct_allocator);
defer bufmap.deinit();
try bufmap.set("x", "1");
testing.expect(mem.eql(u8, bufmap.get("x").?, "1"));
testing.expect(1 == bufmap.count());
try bufmap.set("x", "2");
testing.expect(mem.eql(u8, bufmap.get("x").?, "2"));
testing.expect(1 == bufmap.count());
try bufmap.set("x", "3");
testing.expect(mem.eql(u8, bufmap.get("x").?, "3"));
testing.expect(1 == bufmap.count());
bufmap.delete("x");
testing.expect(0 == bufmap.count());
}