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//! This module contains utilities and data structures for working with enums.
const std = @import("std");
const assert = std.debug.assert;
const testing = std.testing;
const EnumField = std.builtin.Type.EnumField;
/// Increment this value when adding APIs that add single backwards branches.
const eval_branch_quota_cushion = 10;
pub fn fromInt(comptime E: type, integer: anytype) ?E {
const enum_info = @typeInfo(E).@"enum";
if (!enum_info.is_exhaustive) {
if (std.math.cast(enum_info.tag_type, integer)) |tag| {
return @enumFromInt(tag);
}
return null;
}
// We don't directly iterate over the fields of E, as that
// would require an inline loop. Instead, we create an array of
// values that is comptime-know, but can be iterated at runtime
// without requiring an inline loop.
// This generates better machine code.
for (values(E)) |value| {
if (@intFromEnum(value) == integer) return @enumFromInt(integer);
}
return null;
}
/// Returns a struct with a field matching each unique named enum element.
/// If the enum is extern and has multiple names for the same value, only
/// the first name is used. Each field is of type Data and has the provided
/// default, which may be undefined.
pub fn EnumFieldStruct(comptime E: type, comptime Data: type, comptime field_default: ?Data) type {
@setEvalBranchQuota(@typeInfo(E).@"enum".fields.len + eval_branch_quota_cushion);
const default_ptr: ?*const anyopaque = if (field_default) |d| @ptrCast(&d) else null;
return @Struct(.auto, null, std.meta.fieldNames(E), &@splat(Data), &@splat(.{ .default_value_ptr = default_ptr }));
}
/// Looks up the supplied fields in the given enum type.
/// Uses only the field names, field values are ignored.
/// The result array is in the same order as the input.
pub inline fn valuesFromFields(comptime E: type, comptime fields: []const EnumField) []const E {
comptime {
var result: [fields.len]E = undefined;
for (&result, fields) |*r, f| {
r.* = @enumFromInt(f.value);
}
const final = result;
return &final;
}
}
/// Returns the set of all named values in the given enum, in
/// declaration order.
pub fn values(comptime E: type) []const E {
return comptime valuesFromFields(E, @typeInfo(E).@"enum".fields);
}
/// A safe alternative to @tagName() for non-exhaustive enums that doesn't
/// panic when `e` has no tagged value.
/// Returns the tag name for `e` or null if no tag exists.
pub fn tagName(comptime E: type, e: E) ?[:0]const u8 {
return inline for (@typeInfo(E).@"enum".fields) |f| {
if (@intFromEnum(e) == f.value) break f.name;
} else null;
}
test tagName {
const E = enum(u8) { a, b, _ };
try testing.expect(tagName(E, .a) != null);
try testing.expectEqualStrings("a", tagName(E, .a).?);
try testing.expect(tagName(E, @as(E, @enumFromInt(42))) == null);
}
/// Determines the length of a direct-mapped enum array, indexed by
/// @intCast(usize, @intFromEnum(enum_value)).
/// If the enum is non-exhaustive, the resulting length will only be enough
/// to hold all explicit fields.
/// If the enum contains any fields with values that cannot be represented
/// by usize, a compile error is issued. The max_unused_slots parameter limits
/// the total number of items which have no matching enum key (holes in the enum
/// numbering). So for example, if an enum has values 1, 2, 5, and 6, max_unused_slots
/// must be at least 3, to allow unused slots 0, 3, and 4.
pub fn directEnumArrayLen(comptime E: type, comptime max_unused_slots: comptime_int) comptime_int {
var max_value: comptime_int = -1;
const max_usize: comptime_int = ~@as(usize, 0);
const fields = @typeInfo(E).@"enum".fields;
for (fields) |f| {
if (f.value < 0) {
@compileError("Cannot create a direct enum array for " ++ @typeName(E) ++ ", field ." ++ f.name ++ " has a negative value.");
}
if (f.value > max_value) {
if (f.value > max_usize) {
@compileError("Cannot create a direct enum array for " ++ @typeName(E) ++ ", field ." ++ f.name ++ " is larger than the max value of usize.");
}
max_value = f.value;
}
}
const unused_slots = max_value + 1 - fields.len;
if (unused_slots > max_unused_slots) {
const unused_str = std.fmt.comptimePrint("{d}", .{unused_slots});
const allowed_str = std.fmt.comptimePrint("{d}", .{max_unused_slots});
@compileError("Cannot create a direct enum array for " ++ @typeName(E) ++ ". It would have " ++ unused_str ++ " unused slots, but only " ++ allowed_str ++ " are allowed.");
}
return max_value + 1;
}
/// Initializes an array of Data which can be indexed by
/// @intCast(usize, @intFromEnum(enum_value)).
/// If the enum is non-exhaustive, the resulting array will only be large enough
/// to hold all explicit fields.
/// If the enum contains any fields with values that cannot be represented
/// by usize, a compile error is issued. The max_unused_slots parameter limits
/// the total number of items which have no matching enum key (holes in the enum
/// numbering). So for example, if an enum has values 1, 2, 5, and 6, max_unused_slots
/// must be at least 3, to allow unused slots 0, 3, and 4.
/// The init_values parameter must be a struct with field names that match the enum values.
/// If the enum has multiple fields with the same value, the name of the first one must
/// be used.
pub fn directEnumArray(
comptime E: type,
comptime Data: type,
comptime max_unused_slots: comptime_int,
init_values: EnumFieldStruct(E, Data, null),
) [directEnumArrayLen(E, max_unused_slots)]Data {
return directEnumArrayDefault(E, Data, null, max_unused_slots, init_values);
}
test directEnumArray {
const E = enum(i4) { a = 4, b = 6, c = 2 };
var runtime_false: bool = false;
_ = &runtime_false;
const array = directEnumArray(E, bool, 4, .{
.a = true,
.b = runtime_false,
.c = true,
});
try testing.expectEqual([7]bool, @TypeOf(array));
try testing.expectEqual(true, array[4]);
try testing.expectEqual(false, array[6]);
try testing.expectEqual(true, array[2]);
}
/// Initializes an array of Data which can be indexed by
/// @intCast(usize, @intFromEnum(enum_value)). The enum must be exhaustive.
/// If the enum contains any fields with values that cannot be represented
/// by usize, a compile error is issued. The max_unused_slots parameter limits
/// the total number of items which have no matching enum key (holes in the enum
/// numbering). So for example, if an enum has values 1, 2, 5, and 6, max_unused_slots
/// must be at least 3, to allow unused slots 0, 3, and 4.
/// The init_values parameter must be a struct with field names that match the enum values.
/// If the enum has multiple fields with the same value, the name of the first one must
/// be used.
pub fn directEnumArrayDefault(
comptime E: type,
comptime Data: type,
comptime default: ?Data,
comptime max_unused_slots: comptime_int,
init_values: EnumFieldStruct(E, Data, default),
) [directEnumArrayLen(E, max_unused_slots)]Data {
const len = comptime directEnumArrayLen(E, max_unused_slots);
var result: [len]Data = if (default) |d| [_]Data{d} ** len else undefined;
inline for (@typeInfo(@TypeOf(init_values)).@"struct".fields) |f| {
const enum_value = @field(E, f.name);
const index = @as(usize, @intCast(@intFromEnum(enum_value)));
result[index] = @field(init_values, f.name);
}
return result;
}
test directEnumArrayDefault {
const E = enum(i4) { a = 4, b = 6, c = 2 };
var runtime_false: bool = false;
_ = &runtime_false;
const array = directEnumArrayDefault(E, bool, false, 4, .{
.a = true,
.b = runtime_false,
});
try testing.expectEqual([7]bool, @TypeOf(array));
try testing.expectEqual(true, array[4]);
try testing.expectEqual(false, array[6]);
try testing.expectEqual(false, array[2]);
}
test "directEnumArrayDefault slice" {
const E = enum(i4) { a = 4, b = 6, c = 2 };
var runtime_b = "b";
_ = &runtime_b;
const array = directEnumArrayDefault(E, []const u8, "default", 4, .{
.a = "a",
.b = runtime_b,
});
try testing.expectEqual([7][]const u8, @TypeOf(array));
try testing.expectEqualSlices(u8, "a", array[4]);
try testing.expectEqualSlices(u8, "b", array[6]);
try testing.expectEqualSlices(u8, "default", array[2]);
}
/// Deprecated: Use @field(E, @tagName(tag)) or @field(E, string)
pub fn nameCast(comptime E: type, comptime value: anytype) E {
return comptime blk: {
const V = @TypeOf(value);
if (V == E) break :blk value;
const name: ?[]const u8 = switch (@typeInfo(V)) {
.enum_literal, .@"enum" => @tagName(value),
.pointer => value,
else => null,
};
if (name) |n| {
if (@hasField(E, n)) {
break :blk @field(E, n);
}
@compileError("Enum " ++ @typeName(E) ++ " has no field named " ++ n);
}
@compileError("Cannot cast from " ++ @typeName(@TypeOf(value)) ++ " to " ++ @typeName(E));
};
}
test nameCast {
const A = enum(u1) { a = 0, b = 1 };
const B = enum(u1) { a = 1, b = 0 };
try testing.expectEqual(A.a, nameCast(A, .a));
try testing.expectEqual(A.a, nameCast(A, A.a));
try testing.expectEqual(A.a, nameCast(A, B.a));
try testing.expectEqual(A.a, nameCast(A, "a"));
try testing.expectEqual(A.a, nameCast(A, @as(*const [1]u8, "a")));
try testing.expectEqual(A.a, nameCast(A, @as([:0]const u8, "a")));
try testing.expectEqual(A.a, nameCast(A, @as([]const u8, "a")));
try testing.expectEqual(B.a, nameCast(B, .a));
try testing.expectEqual(B.a, nameCast(B, A.a));
try testing.expectEqual(B.a, nameCast(B, B.a));
try testing.expectEqual(B.a, nameCast(B, "a"));
try testing.expectEqual(B.b, nameCast(B, .b));
try testing.expectEqual(B.b, nameCast(B, A.b));
try testing.expectEqual(B.b, nameCast(B, B.b));
try testing.expectEqual(B.b, nameCast(B, "b"));
}
test fromInt {
const E1 = enum {
A,
};
const E2 = enum {
A,
B,
};
const E3 = enum(i8) { A, _ };
var zero: u8 = 0;
var one: u16 = 1;
_ = &zero;
_ = &one;
try testing.expect(fromInt(E1, zero).? == E1.A);
try testing.expect(fromInt(E2, one).? == E2.B);
try testing.expect(fromInt(E3, zero).? == E3.A);
try testing.expect(fromInt(E3, 127).? == @as(E3, @enumFromInt(127)));
try testing.expect(fromInt(E3, -128).? == @as(E3, @enumFromInt(-128)));
try testing.expectEqual(null, fromInt(E1, one));
try testing.expectEqual(null, fromInt(E3, 128));
try testing.expectEqual(null, fromInt(E3, -129));
}
/// A set of enum elements, backed by a bitfield. If the enum
/// is exhaustive but not dense, a mapping will be constructed from enum values
/// to dense indices. This type does no dynamic allocation and
/// can be copied by value.
pub fn EnumSet(comptime E: type) type {
return struct {
const Self = @This();
/// The indexing rules for converting between keys and indices.
pub const Indexer = EnumIndexer(E);
/// The element type for this set.
pub const Key = Indexer.Key;
const BitSet = std.StaticBitSet(Indexer.count);
/// The maximum number of items in this set.
pub const len = Indexer.count;
bits: BitSet = BitSet.initEmpty(),
/// Initializes the set using a struct of bools
pub fn init(init_values: EnumFieldStruct(E, bool, false)) Self {
@setEvalBranchQuota(2 * @typeInfo(E).@"enum".fields.len);
var result: Self = .{};
if (@typeInfo(E).@"enum".is_exhaustive) {
inline for (0..Self.len) |i| {
const key = comptime Indexer.keyForIndex(i);
const tag = @tagName(key);
if (@field(init_values, tag)) {
result.bits.set(i);
}
}
} else {
inline for (std.meta.fields(E)) |field| {
const key = @field(E, field.name);
if (@field(init_values, field.name)) {
const i = comptime Indexer.indexOf(key);
result.bits.set(i);
}
}
}
return result;
}
/// Returns a set containing no keys.
pub fn initEmpty() Self {
return .{ .bits = BitSet.initEmpty() };
}
/// Returns a set containing all possible keys.
pub fn initFull() Self {
return .{ .bits = BitSet.initFull() };
}
/// Returns a set containing multiple keys.
pub fn initMany(keys: []const Key) Self {
var set = initEmpty();
for (keys) |key| set.insert(key);
return set;
}
/// Returns a set containing a single key.
pub fn initOne(key: Key) Self {
return initMany(&[_]Key{key});
}
/// Returns the number of keys in the set.
pub fn count(self: Self) usize {
return self.bits.count();
}
/// Checks if a key is in the set.
pub fn contains(self: Self, key: Key) bool {
return self.bits.isSet(Indexer.indexOf(key));
}
/// Puts a key in the set.
pub fn insert(self: *Self, key: Key) void {
self.bits.set(Indexer.indexOf(key));
}
/// Removes a key from the set.
pub fn remove(self: *Self, key: Key) void {
self.bits.unset(Indexer.indexOf(key));
}
/// Changes the presence of a key in the set to match the passed bool.
pub fn setPresent(self: *Self, key: Key, present: bool) void {
self.bits.setValue(Indexer.indexOf(key), present);
}
/// Toggles the presence of a key in the set. If the key is in
/// the set, removes it. Otherwise adds it.
pub fn toggle(self: *Self, key: Key) void {
self.bits.toggle(Indexer.indexOf(key));
}
/// Toggles the presence of all keys in the passed set.
pub fn toggleSet(self: *Self, other: Self) void {
self.bits.toggleSet(other.bits);
}
/// Toggles all possible keys in the set.
pub fn toggleAll(self: *Self) void {
self.bits.toggleAll();
}
/// Adds all keys in the passed set to this set.
pub fn setUnion(self: *Self, other: Self) void {
self.bits.setUnion(other.bits);
}
/// Removes all keys which are not in the passed set.
pub fn setIntersection(self: *Self, other: Self) void {
self.bits.setIntersection(other.bits);
}
/// Returns true iff both sets have the same keys.
pub fn eql(self: Self, other: Self) bool {
return self.bits.eql(other.bits);
}
/// Returns true iff all the keys in this set are
/// in the other set. The other set may have keys
/// not found in this set.
pub fn subsetOf(self: Self, other: Self) bool {
return self.bits.subsetOf(other.bits);
}
/// Returns true iff this set contains all the keys
/// in the other set. This set may have keys not
/// found in the other set.
pub fn supersetOf(self: Self, other: Self) bool {
return self.bits.supersetOf(other.bits);
}
/// Returns a set with all the keys not in this set.
pub fn complement(self: Self) Self {
return .{ .bits = self.bits.complement() };
}
/// Returns a set with keys that are in either this
/// set or the other set.
pub fn unionWith(self: Self, other: Self) Self {
return .{ .bits = self.bits.unionWith(other.bits) };
}
/// Returns a set with keys that are in both this
/// set and the other set.
pub fn intersectWith(self: Self, other: Self) Self {
return .{ .bits = self.bits.intersectWith(other.bits) };
}
/// Returns a set with keys that are in either this
/// set or the other set, but not both.
pub fn xorWith(self: Self, other: Self) Self {
return .{ .bits = self.bits.xorWith(other.bits) };
}
/// Returns a set with keys that are in this set
/// except for keys in the other set.
pub fn differenceWith(self: Self, other: Self) Self {
return .{ .bits = self.bits.differenceWith(other.bits) };
}
/// Returns an iterator over this set, which iterates in
/// index order. Modifications to the set during iteration
/// may or may not be observed by the iterator, but will
/// not invalidate it.
pub fn iterator(self: *const Self) Iterator {
return .{ .inner = self.bits.iterator(.{}) };
}
pub const Iterator = struct {
inner: BitSet.Iterator(.{}),
pub fn next(self: *Iterator) ?Key {
return if (self.inner.next()) |index|
Indexer.keyForIndex(index)
else
null;
}
};
};
}
/// A map keyed by an enum, backed by a bitfield and a dense array.
/// If the enum is exhaustive but not dense, a mapping will be constructed from
/// enum values to dense indices. This type does no dynamic
/// allocation and can be copied by value.
pub fn EnumMap(comptime E: type, comptime V: type) type {
return struct {
const Self = @This();
/// The index mapping for this map
pub const Indexer = EnumIndexer(E);
/// The key type used to index this map
pub const Key = Indexer.Key;
/// The value type stored in this map
pub const Value = V;
/// The number of possible keys in the map
pub const len = Indexer.count;
const BitSet = std.StaticBitSet(Indexer.count);
/// Bits determining whether items are in the map
bits: BitSet = BitSet.initEmpty(),
/// Values of items in the map. If the associated
/// bit is zero, the value is undefined.
values: [Indexer.count]Value = undefined,
/// Initializes the map using a sparse struct of optionals
pub fn init(init_values: EnumFieldStruct(E, ?Value, @as(?Value, null))) Self {
@setEvalBranchQuota(2 * @typeInfo(E).@"enum".fields.len);
var result: Self = .{};
if (@typeInfo(E).@"enum".is_exhaustive) {
inline for (0..Self.len) |i| {
const key = comptime Indexer.keyForIndex(i);
const tag = @tagName(key);
if (@field(init_values, tag)) |*v| {
result.bits.set(i);
result.values[i] = v.*;
}
}
} else {
inline for (std.meta.fields(E)) |field| {
const key = @field(E, field.name);
if (@field(init_values, field.name)) |*v| {
const i = comptime Indexer.indexOf(key);
result.bits.set(i);
result.values[i] = v.*;
}
}
}
return result;
}
/// Initializes a full mapping with all keys set to value.
/// Consider using EnumArray instead if the map will remain full.
pub fn initFull(value: Value) Self {
var result: Self = .{
.bits = Self.BitSet.initFull(),
.values = undefined,
};
@memset(&result.values, value);
return result;
}
/// Initializes a full mapping with supplied values.
/// Consider using EnumArray instead if the map will remain full.
pub fn initFullWith(init_values: EnumFieldStruct(E, Value, null)) Self {
return initFullWithDefault(null, init_values);
}
/// Initializes a full mapping with a provided default.
/// Consider using EnumArray instead if the map will remain full.
pub fn initFullWithDefault(comptime default: ?Value, init_values: EnumFieldStruct(E, Value, default)) Self {
@setEvalBranchQuota(2 * @typeInfo(E).@"enum".fields.len);
var result: Self = .{
.bits = Self.BitSet.initFull(),
.values = undefined,
};
inline for (0..Self.len) |i| {
const key = comptime Indexer.keyForIndex(i);
const tag = @tagName(key);
result.values[i] = @field(init_values, tag);
}
return result;
}
/// The number of items in the map.
pub fn count(self: Self) usize {
return self.bits.count();
}
/// Checks if the map contains an item.
pub fn contains(self: Self, key: Key) bool {
return self.bits.isSet(Indexer.indexOf(key));
}
/// Gets the value associated with a key.
/// If the key is not in the map, returns null.
pub fn get(self: Self, key: Key) ?Value {
const index = Indexer.indexOf(key);
return if (self.bits.isSet(index)) self.values[index] else null;
}
/// Gets the value associated with a key, which must
/// exist in the map.
pub fn getAssertContains(self: Self, key: Key) Value {
const index = Indexer.indexOf(key);
assert(self.bits.isSet(index));
return self.values[index];
}
/// Gets the address of the value associated with a key.
/// If the key is not in the map, returns null.
pub fn getPtr(self: *Self, key: Key) ?*Value {
const index = Indexer.indexOf(key);
return if (self.bits.isSet(index)) &self.values[index] else null;
}
/// Gets the address of the const value associated with a key.
/// If the key is not in the map, returns null.
pub fn getPtrConst(self: *const Self, key: Key) ?*const Value {
const index = Indexer.indexOf(key);
return if (self.bits.isSet(index)) &self.values[index] else null;
}
/// Gets the address of the value associated with a key.
/// The key must be present in the map.
pub fn getPtrAssertContains(self: *Self, key: Key) *Value {
const index = Indexer.indexOf(key);
assert(self.bits.isSet(index));
return &self.values[index];
}
/// Gets the address of the const value associated with a key.
/// The key must be present in the map.
pub fn getPtrConstAssertContains(self: *const Self, key: Key) *const Value {
const index = Indexer.indexOf(key);
assert(self.bits.isSet(index));
return &self.values[index];
}
/// Adds the key to the map with the supplied value.
/// If the key is already in the map, overwrites the value.
pub fn put(self: *Self, key: Key, value: Value) void {
const index = Indexer.indexOf(key);
self.bits.set(index);
self.values[index] = value;
}
/// Adds the key to the map with an undefined value.
/// If the key is already in the map, the value becomes undefined.
/// A pointer to the value is returned, which should be
/// used to initialize the value.
pub fn putUninitialized(self: *Self, key: Key) *Value {
const index = Indexer.indexOf(key);
self.bits.set(index);
self.values[index] = undefined;
return &self.values[index];
}
/// Sets the value associated with the key in the map,
/// and returns the old value. If the key was not in
/// the map, returns null.
pub fn fetchPut(self: *Self, key: Key, value: Value) ?Value {
const index = Indexer.indexOf(key);
const result: ?Value = if (self.bits.isSet(index)) self.values[index] else null;
self.bits.set(index);
self.values[index] = value;
return result;
}
/// Removes a key from the map. If the key was not in the map,
/// does nothing.
pub fn remove(self: *Self, key: Key) void {
const index = Indexer.indexOf(key);
self.bits.unset(index);
self.values[index] = undefined;
}
/// Removes a key from the map, and returns the old value.
/// If the key was not in the map, returns null.
pub fn fetchRemove(self: *Self, key: Key) ?Value {
const index = Indexer.indexOf(key);
const result: ?Value = if (self.bits.isSet(index)) self.values[index] else null;
self.bits.unset(index);
self.values[index] = undefined;
return result;
}
/// Returns an iterator over the map, which visits items in index order.
/// Modifications to the underlying map may or may not be observed by
/// the iterator, but will not invalidate it.
pub fn iterator(self: *Self) Iterator {
return .{
.inner = self.bits.iterator(.{}),
.values = &self.values,
};
}
/// An entry in the map.
pub const Entry = struct {
/// The key associated with this entry.
/// Modifying this key will not change the map.
key: Key,
/// A pointer to the value in the map associated
/// with this key. Modifications through this
/// pointer will modify the underlying data.
value: *Value,
};
pub const Iterator = struct {
inner: BitSet.Iterator(.{}),
values: *[Indexer.count]Value,
pub fn next(self: *Iterator) ?Entry {
return if (self.inner.next()) |index|
Entry{
.key = Indexer.keyForIndex(index),
.value = &self.values[index],
}
else
null;
}
};
};
}
test EnumMap {
const Ball = enum { red, green, blue };
const some = EnumMap(Ball, u8).init(.{
.green = 0xff,
.blue = 0x80,
});
try testing.expectEqual(2, some.count());
try testing.expectEqual(null, some.get(.red));
try testing.expectEqual(0xff, some.get(.green));
try testing.expectEqual(0x80, some.get(.blue));
}
/// A multiset of enum elements up to a count of usize. Backed
/// by an EnumArray. This type does no dynamic allocation and can
/// be copied by value.
pub fn EnumMultiset(comptime E: type) type {
return BoundedEnumMultiset(E, usize);
}
/// A multiset of enum elements up to CountSize. Backed by an
/// EnumArray. This type does no dynamic allocation and can be
/// copied by value.
pub fn BoundedEnumMultiset(comptime E: type, comptime CountSize: type) type {
return struct {
const Self = @This();
counts: EnumArray(E, CountSize),
/// Initializes the multiset using a struct of counts.
pub fn init(init_counts: EnumFieldStruct(E, CountSize, 0)) Self {
@setEvalBranchQuota(2 * @typeInfo(E).@"enum".fields.len);
var self = initWithCount(0);
inline for (@typeInfo(E).@"enum".fields) |field| {
const c = @field(init_counts, field.name);
const key = @as(E, @enumFromInt(field.value));
self.counts.set(key, c);
}
return self;
}
/// Initializes the multiset with a count of zero.
pub fn initEmpty() Self {
return initWithCount(0);
}
/// Initializes the multiset with all keys at the
/// same count.
pub fn initWithCount(comptime c: CountSize) Self {
return .{
.counts = EnumArray(E, CountSize).initDefault(c, .{}),
};
}
/// Returns the total number of key counts in the multiset.
pub fn count(self: Self) usize {
var sum: usize = 0;
for (self.counts.values) |c| {
sum += c;
}
return sum;
}
/// Checks if at least one key in multiset.
pub fn contains(self: Self, key: E) bool {
return self.counts.get(key) > 0;
}
/// Removes all instance of a key from multiset. Same as
/// setCount(key, 0).
pub fn removeAll(self: *Self, key: E) void {
return self.counts.set(key, 0);
}
/// Increases the key count by given amount. Caller asserts
/// operation will not overflow.
pub fn addAssertSafe(self: *Self, key: E, c: CountSize) void {
self.counts.getPtr(key).* += c;
}
/// Increases the key count by given amount.
pub fn add(self: *Self, key: E, c: CountSize) error{Overflow}!void {
self.counts.set(key, try std.math.add(CountSize, self.counts.get(key), c));
}
/// Decreases the key count by given amount. If amount is
/// greater than the number of keys in multset, then key count
/// will be set to zero.
pub fn remove(self: *Self, key: E, c: CountSize) void {
self.counts.getPtr(key).* -= @min(self.getCount(key), c);
}
/// Returns the count for a key.
pub fn getCount(self: Self, key: E) CountSize {
return self.counts.get(key);
}
/// Set the count for a key.
pub fn setCount(self: *Self, key: E, c: CountSize) void {
self.counts.set(key, c);
}
/// Increases the all key counts by given multiset. Caller
/// asserts operation will not overflow any key.
pub fn addSetAssertSafe(self: *Self, other: Self) void {
inline for (@typeInfo(E).@"enum".fields) |field| {
const key = @as(E, @enumFromInt(field.value));
self.addAssertSafe(key, other.getCount(key));
}
}
/// Increases the all key counts by given multiset.
pub fn addSet(self: *Self, other: Self) error{Overflow}!void {
inline for (@typeInfo(E).@"enum".fields) |field| {
const key = @as(E, @enumFromInt(field.value));
try self.add(key, other.getCount(key));
}
}
/// Decreases the all key counts by given multiset. If
/// the given multiset has more key counts than this,
/// then that key will have a key count of zero.
pub fn removeSet(self: *Self, other: Self) void {
inline for (@typeInfo(E).@"enum".fields) |field| {
const key = @as(E, @enumFromInt(field.value));
self.remove(key, other.getCount(key));
}
}
/// Returns true iff all key counts are the same as
/// given multiset.
pub fn eql(self: Self, other: Self) bool {
inline for (@typeInfo(E).@"enum".fields) |field| {
const key = @as(E, @enumFromInt(field.value));
if (self.getCount(key) != other.getCount(key)) {
return false;
}
}
return true;
}
/// Returns true iff all key counts less than or
/// equal to the given multiset.
pub fn subsetOf(self: Self, other: Self) bool {
inline for (@typeInfo(E).@"enum".fields) |field| {
const key = @as(E, @enumFromInt(field.value));
if (self.getCount(key) > other.getCount(key)) {
return false;
}
}
return true;
}
/// Returns true iff all key counts greater than or
/// equal to the given multiset.
pub fn supersetOf(self: Self, other: Self) bool {
inline for (@typeInfo(E).@"enum".fields) |field| {
const key = @as(E, @enumFromInt(field.value));
if (self.getCount(key) < other.getCount(key)) {
return false;
}
}
return true;
}
/// Returns a multiset with the total key count of this
/// multiset and the other multiset. Caller asserts
/// operation will not overflow any key.
pub fn plusAssertSafe(self: Self, other: Self) Self {
var result = self;
result.addSetAssertSafe(other);
return result;
}
/// Returns a multiset with the total key count of this
/// multiset and the other multiset.
pub fn plus(self: Self, other: Self) error{Overflow}!Self {
var result = self;
try result.addSet(other);
return result;
}
/// Returns a multiset with the key count of this
/// multiset minus the corresponding key count in the
/// other multiset. If the other multiset contains
/// more key count than this set, that key will have
/// a count of zero.
pub fn minus(self: Self, other: Self) Self {
var result = self;
result.removeSet(other);
return result;
}
pub const Entry = EnumArray(E, CountSize).Entry;
pub const Iterator = EnumArray(E, CountSize).Iterator;
/// Returns an iterator over this multiset. Keys with zero
/// counts are included. Modifications to the set during
/// iteration may or may not be observed by the iterator,
/// but will not invalidate it.
pub fn iterator(self: *Self) Iterator {
return self.counts.iterator();
}
};
}
test EnumMultiset {
const Ball = enum { red, green, blue };
const empty = EnumMultiset(Ball).initEmpty();
const r0_g1_b2 = EnumMultiset(Ball).init(.{
.red = 0,
.green = 1,
.blue = 2,
});
const ten_of_each = EnumMultiset(Ball).initWithCount(10);
try testing.expectEqual(empty.count(), 0);
try testing.expectEqual(r0_g1_b2.count(), 3);
try testing.expectEqual(ten_of_each.count(), 30);
try testing.expect(!empty.contains(.red));
try testing.expect(!empty.contains(.green));
try testing.expect(!empty.contains(.blue));
try testing.expect(!r0_g1_b2.contains(.red));
try testing.expect(r0_g1_b2.contains(.green));
try testing.expect(r0_g1_b2.contains(.blue));
try testing.expect(ten_of_each.contains(.red));
try testing.expect(ten_of_each.contains(.green));
try testing.expect(ten_of_each.contains(.blue));
{
var copy = ten_of_each;
copy.removeAll(.red);
try testing.expect(!copy.contains(.red));
// removeAll second time does nothing
copy.removeAll(.red);
try testing.expect(!copy.contains(.red));
}
{
var copy = ten_of_each;
copy.addAssertSafe(.red, 6);
try testing.expectEqual(copy.getCount(.red), 16);
}
{
var copy = ten_of_each;
try copy.add(.red, 6);
try testing.expectEqual(copy.getCount(.red), 16);
try testing.expectError(error.Overflow, copy.add(.red, std.math.maxInt(usize)));
}
{
var copy = ten_of_each;
copy.remove(.red, 4);
try testing.expectEqual(copy.getCount(.red), 6);
// subtracting more it contains does not underflow
copy.remove(.green, 14);
try testing.expectEqual(copy.getCount(.green), 0);
}
try testing.expectEqual(empty.getCount(.green), 0);
try testing.expectEqual(r0_g1_b2.getCount(.green), 1);
try testing.expectEqual(ten_of_each.getCount(.green), 10);
{
var copy = empty;
copy.setCount(.red, 6);
try testing.expectEqual(copy.getCount(.red), 6);
}
{
var copy = r0_g1_b2;
copy.addSetAssertSafe(ten_of_each);
try testing.expectEqual(copy.getCount(.red), 10);
try testing.expectEqual(copy.getCount(.green), 11);
try testing.expectEqual(copy.getCount(.blue), 12);
}
{
var copy = r0_g1_b2;
try copy.addSet(ten_of_each);
try testing.expectEqual(copy.getCount(.red), 10);
try testing.expectEqual(copy.getCount(.green), 11);
try testing.expectEqual(copy.getCount(.blue), 12);
const full = EnumMultiset(Ball).initWithCount(std.math.maxInt(usize));
try testing.expectError(error.Overflow, copy.addSet(full));
}
{
var copy = ten_of_each;
copy.removeSet(r0_g1_b2);
try testing.expectEqual(copy.getCount(.red), 10);
try testing.expectEqual(copy.getCount(.green), 9);
try testing.expectEqual(copy.getCount(.blue), 8);
copy.removeSet(ten_of_each);
try testing.expectEqual(copy.getCount(.red), 0);
try testing.expectEqual(copy.getCount(.green), 0);
try testing.expectEqual(copy.getCount(.blue), 0);
}
try testing.expect(empty.eql(empty));
try testing.expect(r0_g1_b2.eql(r0_g1_b2));
try testing.expect(ten_of_each.eql(ten_of_each));
try testing.expect(!empty.eql(r0_g1_b2));
try testing.expect(!r0_g1_b2.eql(ten_of_each));
try testing.expect(!ten_of_each.eql(empty));
try testing.expect(empty.subsetOf(empty));
try testing.expect(r0_g1_b2.subsetOf(r0_g1_b2));