126 lines
4.2 KiB
Zig
126 lines
4.2 KiB
Zig
const std = @import("std.zig");
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const StringHashMap = std.StringHashMap;
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const mem = std.mem;
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const Allocator = mem.Allocator;
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const testing = std.testing;
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/// BufMap copies keys and values before they go into the map, and
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/// frees them when they get removed.
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pub const BufMap = struct {
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hash_map: BufMapHashMap,
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const BufMapHashMap = StringHashMap([]const u8);
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/// Create a BufMap backed by a specific allocator.
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/// That allocator will be used for both backing allocations
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/// and string deduplication.
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pub fn init(allocator: Allocator) BufMap {
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var self = BufMap{ .hash_map = BufMapHashMap.init(allocator) };
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return self;
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}
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/// Free the backing storage of the map, as well as all
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/// of the stored keys and values.
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pub fn deinit(self: *BufMap) void {
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var it = self.hash_map.iterator();
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while (it.next()) |entry| {
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self.free(entry.key_ptr.*);
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self.free(entry.value_ptr.*);
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}
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self.hash_map.deinit();
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}
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/// Same as `put` but the key and value become owned by the BufMap rather
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/// than being copied.
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/// If `putMove` fails, the ownership of key and value does not transfer.
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pub fn putMove(self: *BufMap, key: []u8, value: []u8) !void {
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const get_or_put = try self.hash_map.getOrPut(key);
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if (get_or_put.found_existing) {
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self.free(get_or_put.key_ptr.*);
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self.free(get_or_put.value_ptr.*);
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get_or_put.key_ptr.* = key;
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}
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get_or_put.value_ptr.* = value;
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}
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/// `key` and `value` are copied into the BufMap.
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pub fn put(self: *BufMap, key: []const u8, value: []const u8) !void {
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const value_copy = try self.copy(value);
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errdefer self.free(value_copy);
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const get_or_put = try self.hash_map.getOrPut(key);
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if (get_or_put.found_existing) {
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self.free(get_or_put.value_ptr.*);
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} else {
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get_or_put.key_ptr.* = self.copy(key) catch |err| {
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_ = self.hash_map.remove(key);
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return err;
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};
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}
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get_or_put.value_ptr.* = value_copy;
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}
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/// Find the address of the value associated with a key.
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/// The returned pointer is invalidated if the map resizes.
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pub fn getPtr(self: BufMap, key: []const u8) ?*[]const u8 {
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return self.hash_map.getPtr(key);
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}
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/// Return the map's copy of the value associated with
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/// a key. The returned string is invalidated if this
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/// key is removed from the map.
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pub fn get(self: BufMap, key: []const u8) ?[]const u8 {
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return self.hash_map.get(key);
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}
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/// Removes the item from the map and frees its value.
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/// This invalidates the value returned by get() for this key.
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pub fn remove(self: *BufMap, key: []const u8) void {
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const kv = self.hash_map.fetchRemove(key) orelse return;
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self.free(kv.key);
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self.free(kv.value);
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}
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/// Returns the number of KV pairs stored in the map.
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pub fn count(self: BufMap) BufMapHashMap.Size {
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return self.hash_map.count();
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}
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/// Returns an iterator over entries in the map.
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pub fn iterator(self: *const BufMap) BufMapHashMap.Iterator {
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return self.hash_map.iterator();
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}
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fn free(self: BufMap, value: []const u8) void {
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self.hash_map.allocator.free(value);
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}
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fn copy(self: BufMap, value: []const u8) ![]u8 {
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return self.hash_map.allocator.dupe(u8, value);
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}
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};
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test "BufMap" {
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const allocator = std.testing.allocator;
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var bufmap = BufMap.init(allocator);
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defer bufmap.deinit();
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try bufmap.put("x", "1");
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try testing.expect(mem.eql(u8, bufmap.get("x").?, "1"));
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try testing.expect(1 == bufmap.count());
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try bufmap.put("x", "2");
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try testing.expect(mem.eql(u8, bufmap.get("x").?, "2"));
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try testing.expect(1 == bufmap.count());
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try bufmap.put("x", "3");
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try testing.expect(mem.eql(u8, bufmap.get("x").?, "3"));
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try testing.expect(1 == bufmap.count());
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bufmap.remove("x");
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try testing.expect(0 == bufmap.count());
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try bufmap.putMove(try allocator.dupe(u8, "k"), try allocator.dupe(u8, "v1"));
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try bufmap.putMove(try allocator.dupe(u8, "k"), try allocator.dupe(u8, "v2"));
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}
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