Commit 5bf63bfbf1
Changed files (1)
std
std/hash_map.zig
@@ -522,8 +522,9 @@ pub fn getTrivialEqlFn(comptime K: type) (fn (K, K) bool) {
pub fn getAutoHashFn(comptime K: type) (fn (K) u32) {
return struct {
fn hash(key: K) u32 {
- const h = autoHash(key, 0);
- return @truncate(u32, h);
+ var hasher = Wyhash.init(0);
+ autoHash(&hasher, key);
+ return @truncate(u32, hasher.final());
}
}.hash;
}
@@ -538,10 +539,7 @@ pub fn getAutoEqlFn(comptime K: type) (fn (K, K) bool) {
/// Provides generic hashing for any eligible type.
/// Only hashes `key` itself, pointers are not followed.
-/// The underlying hashing algorithm is wyhash.
-pub fn autoHash(key: var, seed: u64) u64 {
- // We use the fact that wyhash takes an input seed to "chain" hasing when the
- // key has multiple parts that are not necessarily contiguous in memory.
+pub fn autoHash(hasher: var, key: var) void {
const Key = @typeOf(key);
switch (@typeInfo(Key)) {
builtin.TypeId.NoReturn,
@@ -557,91 +555,101 @@ pub fn autoHash(key: var, seed: u64) u64 {
builtin.TypeId.EnumLiteral,
=> @compileError("cannot hash this type"),
- builtin.TypeId.Int => return Wyhash.hash(seed, std.mem.asBytes(&key)),
+ builtin.TypeId.Int => hasher.update(std.mem.asBytes(&key)),
- builtin.TypeId.Float => |info| return autoHash(@bitCast(@IntType(false, info.bits), key), seed),
+ builtin.TypeId.Float => |info| autoHash(hasher, @bitCast(@IntType(false, info.bits), key)),
- builtin.TypeId.Bool => return autoHash(@boolToInt(key), seed),
- builtin.TypeId.Enum => return autoHash(@enumToInt(key), seed),
- builtin.TypeId.ErrorSet => return autoHash(@errorToInt(key), seed),
- builtin.TypeId.Promise, builtin.TypeId.Fn => return autoHash(@ptrToInt(key), seed),
+ builtin.TypeId.Bool => autoHash(hasher, @boolToInt(key)),
+ builtin.TypeId.Enum => autoHash(hasher, @enumToInt(key)),
+ builtin.TypeId.ErrorSet => autoHash(hasher, @errorToInt(key)),
+ builtin.TypeId.Promise, builtin.TypeId.Fn => autoHash(hasher, @ptrToInt(key)),
- builtin.TypeId.Pointer => |info| return switch (info.size) {
+ builtin.TypeId.Pointer => |info| switch (info.size) {
builtin.TypeInfo.Pointer.Size.One,
builtin.TypeInfo.Pointer.Size.Many,
builtin.TypeInfo.Pointer.Size.C,
- => return autoHash(@ptrToInt(key), seed),
+ => autoHash(hasher, @ptrToInt(key)),
- builtin.TypeInfo.Pointer.Size.Slice => return autoHash(key.len, autoHash(key.ptr, seed)),
+ builtin.TypeInfo.Pointer.Size.Slice => {
+ autoHash(hasher, key.ptr);
+ autoHash(hasher, key.len);
+ },
},
- builtin.TypeId.Optional => return if (key) |k| autoHash(k, seed) else 0,
+ builtin.TypeId.Optional => if (key) |k| autoHash(hasher, k),
builtin.TypeId.Array => {
// TODO detect via a trait when Key has no padding bits to
// hash it as an array of bytes.
// Otherwise, hash every element.
- var s = seed;
for (key) |element| {
- // We reuse the hash of the previous element as the seed for the
- // next one so that they're dependant.
- s = autoHash(element, s);
+ autoHash(hasher, element);
}
- return s;
},
builtin.TypeId.Vector => |info| {
- // If there's no unused bits in the child type, we can just hash
- // this as an array of bytes.
if (info.child.bit_count % 8 == 0) {
- return Wyhash.hash(seed, mem.asBytes(&key));
- }
-
- // Otherwise, hash every element.
- var s = seed;
- // TODO remove the copy to an array once field access is done.
- const array: [info.len]info.child = key;
- comptime var i: u32 = 0;
- inline while (i < info.len) : (i += 1) {
- s = autoHash(array[i], s);
+ // If there's no unused bits in the child type, we can just hash
+ // this as an array of bytes.
+ hasher.update(mem.asBytes(&key));
+ } else {
+ // Otherwise, hash every element.
+ // TODO remove the copy to an array once field access is done.
+ const array: [info.len]info.child = key;
+ comptime var i: u32 = 0;
+ inline while (i < info.len) : (i += 1) {
+ autoHash(hasher, array[i]);
+ }
}
- return s;
},
builtin.TypeId.Struct => |info| {
// TODO detect via a trait when Key has no padding bits to
// hash it as an array of bytes.
// Otherwise, hash every field.
- var s = seed;
inline for (info.fields) |field| {
// We reuse the hash of the previous field as the seed for the
// next one so that they're dependant.
- s = autoHash(@field(key, field.name), s);
+ autoHash(hasher, @field(key, field.name));
}
- return s;
},
- builtin.TypeId.Union => |info| {
+ builtin.TypeId.Union => |info| blk: {
if (info.tag_type) |tag_type| {
const tag = meta.activeTag(key);
- const s = autoHash(tag, seed);
+ const s = autoHash(hasher, tag);
inline for (info.fields) |field| {
const enum_field = field.enum_field.?;
if (enum_field.value == @enumToInt(tag)) {
- return autoHash(@field(key, enum_field.name), s);
+ autoHash(hasher, @field(key, enum_field.name));
+ // TODO use a labelled break when it does not crash the compiler.
+ // break :blk;
+ return;
}
}
unreachable;
} else @compileError("cannot hash untagged union type: " ++ @typeName(Key) ++ ", provide your own hash function");
},
- builtin.TypeId.ErrorUnion => {
- return autoHash(key catch |err| return autoHash(err, seed), seed);
+ builtin.TypeId.ErrorUnion => blk: {
+ const payload = key catch |err| {
+ autoHash(hasher, err);
+ break :blk;
+ };
+ autoHash(hasher, payload);
},
}
}
+fn testAutoHash(key: var) u64 {
+ var hasher = Wyhash.init(0);
+ autoHash(&hasher, key);
+ return hasher.final();
+}
+
test "autoHash slice" {
+ // Allocate one array dynamically so that we're assured it is not merged
+ // with the other by the optimization passes.
const array1 = try std.heap.direct_allocator.create([6]u32);
defer std.heap.direct_allocator.destroy(array1);
array1.* = [_]u32{ 1, 2, 3, 4, 5, 6 };
@@ -649,38 +657,46 @@ test "autoHash slice" {
const a = array1[0..];
const b = array2[0..];
const c = array1[0..3];
- testing.expect(autoHash(a, 0) == autoHash(a, 0));
- testing.expect(autoHash(a, 0) != autoHash(array1, 0));
- testing.expect(autoHash(a, 0) != autoHash(b, 0));
- testing.expect(autoHash(a, 0) != autoHash(c, 0));
+ testing.expect(testAutoHash(a) == testAutoHash(a));
+ testing.expect(testAutoHash(a) != testAutoHash(array1));
+ testing.expect(testAutoHash(a) != testAutoHash(b));
+ testing.expect(testAutoHash(a) != testAutoHash(c));
}
-test "autoHash optional" {
+test "testAutoHash optional" {
const a: ?u32 = 123;
const b: ?u32 = null;
- testing.expectEqual(autoHash(a, 0), autoHash(u32(123), 0));
- testing.expect(autoHash(a, 0) != autoHash(b, 0));
- testing.expectEqual(autoHash(b, 0), 0);
+ testing.expectEqual(testAutoHash(a), testAutoHash(u32(123)));
+ testing.expect(testAutoHash(a) != testAutoHash(b));
+ testing.expectEqual(testAutoHash(b), 0);
}
-test "autoHash array" {
+test "testAutoHash array" {
const a = [_]u32{ 1, 2, 3 };
- const h = autoHash(a, 0);
- testing.expectEqual(h, autoHash(u32(3), autoHash(u32(2), autoHash(u32(1), 0))));
+ const h = testAutoHash(a);
+ var hasher = Wyhash.init(0);
+ autoHash(&hasher, u32(1));
+ autoHash(&hasher, u32(2));
+ autoHash(&hasher, u32(3));
+ testing.expectEqual(h, hasher.final());
}
-test "autoHash struct" {
+test "testAutoHash struct" {
const Foo = struct {
a: u32 = 1,
b: u32 = 2,
c: u32 = 3,
};
const f = Foo{};
- const h = autoHash(f, 0);
- testing.expectEqual(h, autoHash(u32(3), autoHash(u32(2), autoHash(u32(1), 0))));
+ const h = testAutoHash(f);
+ var hasher = Wyhash.init(0);
+ autoHash(&hasher, u32(1));
+ autoHash(&hasher, u32(2));
+ autoHash(&hasher, u32(3));
+ testing.expectEqual(h, hasher.final());
}
-test "autoHash union" {
+test "testAutoHash union" {
const Foo = union(enum) {
A: u32,
B: f32,
@@ -690,24 +706,24 @@ test "autoHash union" {
const a = Foo{ .A = 18 };
var b = Foo{ .B = 12.34 };
const c = Foo{ .C = 18 };
- testing.expect(autoHash(a, 0) == autoHash(a, 0));
- testing.expect(autoHash(a, 0) != autoHash(b, 0));
- testing.expect(autoHash(a, 0) != autoHash(c, 0));
+ testing.expect(testAutoHash(a) == testAutoHash(a));
+ testing.expect(testAutoHash(a) != testAutoHash(b));
+ testing.expect(testAutoHash(a) != testAutoHash(c));
b = Foo{ .A = 18 };
- testing.expect(autoHash(a, 0) == autoHash(b, 0));
+ testing.expect(testAutoHash(a) == testAutoHash(b));
}
-test "autoHash vector" {
+test "testAutoHash vector" {
const a: @Vector(4, u32) = [_]u32{ 1, 2, 3, 4 };
const b: @Vector(4, u32) = [_]u32{ 1, 2, 3, 5 };
const c: @Vector(4, u31) = [_]u31{ 1, 2, 3, 4 };
- testing.expect(autoHash(a, 0) == autoHash(a, 0));
- testing.expect(autoHash(a, 0) != autoHash(b, 0));
- testing.expect(autoHash(a, 0) != autoHash(c, 0));
+ testing.expect(testAutoHash(a) == testAutoHash(a));
+ testing.expect(testAutoHash(a) != testAutoHash(b));
+ testing.expect(testAutoHash(a) != testAutoHash(c));
}
-test "autoHash error union" {
+test "testAutoHash error union" {
const Errors = error{Test};
const Foo = struct {
a: u32 = 1,
@@ -716,7 +732,7 @@ test "autoHash error union" {
};
const f = Foo{};
const g: Errors!Foo = Errors.Test;
- testing.expect(autoHash(f, 0) != autoHash(g, 0));
- testing.expect(autoHash(f, 0) == autoHash(Foo{}, 0));
- testing.expect(autoHash(g, 0) == autoHash(Errors.Test, 0));
+ testing.expect(testAutoHash(f) != testAutoHash(g));
+ testing.expect(testAutoHash(f) == testAutoHash(Foo{}));
+ testing.expect(testAutoHash(g) == testAutoHash(Errors.Test));
}