852 lines
32 KiB
Zig
852 lines
32 KiB
Zig
//! This module contains utilities and data structures for working with enums.
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const std = @import("std.zig");
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const assert = std.debug.assert;
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const testing = std.testing;
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const EnumField = std.builtin.Type.EnumField;
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/// Returns a struct with a field matching each unique named enum element.
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/// If the enum is extern and has multiple names for the same value, only
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/// the first name is used. Each field is of type Data and has the provided
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/// default, which may be undefined.
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pub fn EnumFieldStruct(comptime E: type, comptime Data: type, comptime field_default: ?Data) type {
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const StructField = std.builtin.Type.StructField;
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var fields: []const StructField = &[_]StructField{};
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for (std.meta.fields(E)) |field| {
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fields = fields ++ &[_]StructField{.{
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.name = field.name,
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.field_type = Data,
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.default_value = if (field_default) |d| &d else null,
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.is_comptime = false,
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.alignment = if (@sizeOf(Data) > 0) @alignOf(Data) else 0,
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}};
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}
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return @Type(.{ .Struct = .{
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.layout = .Auto,
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.fields = fields,
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.decls = &.{},
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.is_tuple = false,
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} });
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}
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/// Looks up the supplied fields in the given enum type.
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/// Uses only the field names, field values are ignored.
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/// The result array is in the same order as the input.
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pub fn valuesFromFields(comptime E: type, comptime fields: []const EnumField) []const E {
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comptime {
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var result: [fields.len]E = undefined;
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for (fields) |f, i| {
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result[i] = @field(E, f.name);
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}
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return &result;
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}
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}
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/// Returns the set of all named values in the given enum, in
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/// declaration order.
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pub fn values(comptime E: type) []const E {
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return comptime valuesFromFields(E, @typeInfo(E).Enum.fields);
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}
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/// Determines the length of a direct-mapped enum array, indexed by
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/// @intCast(usize, @enumToInt(enum_value)).
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/// If the enum is non-exhaustive, the resulting length will only be enough
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/// to hold all explicit fields.
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/// If the enum contains any fields with values that cannot be represented
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/// by usize, a compile error is issued. The max_unused_slots parameter limits
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/// the total number of items which have no matching enum key (holes in the enum
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/// numbering). So for example, if an enum has values 1, 2, 5, and 6, max_unused_slots
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/// must be at least 3, to allow unused slots 0, 3, and 4.
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pub fn directEnumArrayLen(comptime E: type, comptime max_unused_slots: comptime_int) comptime_int {
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var max_value: comptime_int = -1;
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const max_usize: comptime_int = ~@as(usize, 0);
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const fields = std.meta.fields(E);
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for (fields) |f| {
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if (f.value < 0) {
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@compileError("Cannot create a direct enum array for " ++ @typeName(E) ++ ", field ." ++ f.name ++ " has a negative value.");
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}
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if (f.value > max_value) {
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if (f.value > max_usize) {
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@compileError("Cannot create a direct enum array for " ++ @typeName(E) ++ ", field ." ++ f.name ++ " is larger than the max value of usize.");
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}
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max_value = f.value;
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}
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}
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const unused_slots = max_value + 1 - fields.len;
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if (unused_slots > max_unused_slots) {
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const unused_str = std.fmt.comptimePrint("{d}", .{unused_slots});
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const allowed_str = std.fmt.comptimePrint("{d}", .{max_unused_slots});
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@compileError("Cannot create a direct enum array for " ++ @typeName(E) ++ ". It would have " ++ unused_str ++ " unused slots, but only " ++ allowed_str ++ " are allowed.");
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}
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return max_value + 1;
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}
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/// Initializes an array of Data which can be indexed by
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/// @intCast(usize, @enumToInt(enum_value)).
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/// If the enum is non-exhaustive, the resulting array will only be large enough
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/// to hold all explicit fields.
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/// If the enum contains any fields with values that cannot be represented
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/// by usize, a compile error is issued. The max_unused_slots parameter limits
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/// the total number of items which have no matching enum key (holes in the enum
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/// numbering). So for example, if an enum has values 1, 2, 5, and 6, max_unused_slots
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/// must be at least 3, to allow unused slots 0, 3, and 4.
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/// The init_values parameter must be a struct with field names that match the enum values.
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/// If the enum has multiple fields with the same value, the name of the first one must
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/// be used.
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pub fn directEnumArray(
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comptime E: type,
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comptime Data: type,
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comptime max_unused_slots: comptime_int,
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init_values: EnumFieldStruct(E, Data, null),
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) [directEnumArrayLen(E, max_unused_slots)]Data {
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return directEnumArrayDefault(E, Data, null, max_unused_slots, init_values);
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}
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test "std.enums.directEnumArray" {
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const E = enum(i4) { a = 4, b = 6, c = 2 };
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var runtime_false: bool = false;
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const array = directEnumArray(E, bool, 4, .{
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.a = true,
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.b = runtime_false,
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.c = true,
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});
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try testing.expectEqual([7]bool, @TypeOf(array));
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try testing.expectEqual(true, array[4]);
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try testing.expectEqual(false, array[6]);
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try testing.expectEqual(true, array[2]);
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}
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/// Initializes an array of Data which can be indexed by
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/// @intCast(usize, @enumToInt(enum_value)). The enum must be exhaustive.
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/// If the enum contains any fields with values that cannot be represented
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/// by usize, a compile error is issued. The max_unused_slots parameter limits
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/// the total number of items which have no matching enum key (holes in the enum
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/// numbering). So for example, if an enum has values 1, 2, 5, and 6, max_unused_slots
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/// must be at least 3, to allow unused slots 0, 3, and 4.
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/// The init_values parameter must be a struct with field names that match the enum values.
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/// If the enum has multiple fields with the same value, the name of the first one must
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/// be used.
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pub fn directEnumArrayDefault(
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comptime E: type,
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comptime Data: type,
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comptime default: ?Data,
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comptime max_unused_slots: comptime_int,
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init_values: EnumFieldStruct(E, Data, default),
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) [directEnumArrayLen(E, max_unused_slots)]Data {
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const len = comptime directEnumArrayLen(E, max_unused_slots);
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var result: [len]Data = if (default) |d| [_]Data{d} ** len else undefined;
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inline for (@typeInfo(@TypeOf(init_values)).Struct.fields) |f| {
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const enum_value = @field(E, f.name);
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const index = @intCast(usize, @enumToInt(enum_value));
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result[index] = @field(init_values, f.name);
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}
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return result;
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}
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test "std.enums.directEnumArrayDefault" {
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const E = enum(i4) { a = 4, b = 6, c = 2 };
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var runtime_false: bool = false;
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const array = directEnumArrayDefault(E, bool, false, 4, .{
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.a = true,
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.b = runtime_false,
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});
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try testing.expectEqual([7]bool, @TypeOf(array));
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try testing.expectEqual(true, array[4]);
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try testing.expectEqual(false, array[6]);
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try testing.expectEqual(false, array[2]);
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}
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/// Cast an enum literal, value, or string to the enum value of type E
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/// with the same name.
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pub fn nameCast(comptime E: type, comptime value: anytype) E {
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comptime {
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const V = @TypeOf(value);
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if (V == E) return value;
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var name: ?[]const u8 = switch (@typeInfo(V)) {
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.EnumLiteral, .Enum => @tagName(value),
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.Pointer => if (std.meta.trait.isZigString(V)) value else null,
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else => null,
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};
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if (name) |n| {
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if (@hasField(E, n)) {
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return @field(E, n);
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}
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@compileError("Enum " ++ @typeName(E) ++ " has no field named " ++ n);
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}
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@compileError("Cannot cast from " ++ @typeName(@TypeOf(value)) ++ " to " ++ @typeName(E));
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}
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}
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test "std.enums.nameCast" {
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const A = enum(u1) { a = 0, b = 1 };
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const B = enum(u1) { a = 1, b = 0 };
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try testing.expectEqual(A.a, nameCast(A, .a));
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try testing.expectEqual(A.a, nameCast(A, A.a));
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try testing.expectEqual(A.a, nameCast(A, B.a));
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try testing.expectEqual(A.a, nameCast(A, "a"));
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try testing.expectEqual(A.a, nameCast(A, @as(*const [1]u8, "a")));
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try testing.expectEqual(A.a, nameCast(A, @as([:0]const u8, "a")));
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try testing.expectEqual(A.a, nameCast(A, @as([]const u8, "a")));
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try testing.expectEqual(B.a, nameCast(B, .a));
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try testing.expectEqual(B.a, nameCast(B, A.a));
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try testing.expectEqual(B.a, nameCast(B, B.a));
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try testing.expectEqual(B.a, nameCast(B, "a"));
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try testing.expectEqual(B.b, nameCast(B, .b));
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try testing.expectEqual(B.b, nameCast(B, A.b));
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try testing.expectEqual(B.b, nameCast(B, B.b));
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try testing.expectEqual(B.b, nameCast(B, "b"));
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}
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/// A set of enum elements, backed by a bitfield. If the enum
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/// is not dense, a mapping will be constructed from enum values
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/// to dense indices. This type does no dynamic allocation and
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/// can be copied by value.
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pub fn EnumSet(comptime E: type) type {
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const mixin = struct {
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fn EnumSetExt(comptime Self: type) type {
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const Indexer = Self.Indexer;
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return struct {
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/// Initializes the set using a struct of bools
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pub fn init(init_values: EnumFieldStruct(E, bool, false)) Self {
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var result = Self{};
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comptime var i: usize = 0;
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inline while (i < Self.len) : (i += 1) {
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const key = comptime Indexer.keyForIndex(i);
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const tag = comptime @tagName(key);
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if (@field(init_values, tag)) {
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result.bits.set(i);
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}
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}
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return result;
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}
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};
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}
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};
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return IndexedSet(EnumIndexer(E), mixin.EnumSetExt);
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}
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/// A map keyed by an enum, backed by a bitfield and a dense array.
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/// If the enum is not dense, a mapping will be constructed from
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/// enum values to dense indices. This type does no dynamic
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/// allocation and can be copied by value.
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pub fn EnumMap(comptime E: type, comptime V: type) type {
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const mixin = struct {
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fn EnumMapExt(comptime Self: type) type {
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const Indexer = Self.Indexer;
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return struct {
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/// Initializes the map using a sparse struct of optionals
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pub fn init(init_values: EnumFieldStruct(E, ?V, @as(?V, null))) Self {
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var result = Self{};
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comptime var i: usize = 0;
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inline while (i < Self.len) : (i += 1) {
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const key = comptime Indexer.keyForIndex(i);
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const tag = comptime @tagName(key);
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if (@field(init_values, tag)) |*v| {
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result.bits.set(i);
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result.values[i] = v.*;
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}
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}
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return result;
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}
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/// Initializes a full mapping with all keys set to value.
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/// Consider using EnumArray instead if the map will remain full.
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pub fn initFull(value: V) Self {
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var result = Self{
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.bits = Self.BitSet.initFull(),
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.values = undefined,
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};
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std.mem.set(V, &result.values, value);
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return result;
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}
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/// Initializes a full mapping with supplied values.
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/// Consider using EnumArray instead if the map will remain full.
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pub fn initFullWith(init_values: EnumFieldStruct(E, V, @as(?V, null))) Self {
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return initFullWithDefault(@as(?V, null), init_values);
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}
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/// Initializes a full mapping with a provided default.
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/// Consider using EnumArray instead if the map will remain full.
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pub fn initFullWithDefault(comptime default: ?V, init_values: EnumFieldStruct(E, V, default)) Self {
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var result = Self{
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.bits = Self.BitSet.initFull(),
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.values = undefined,
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};
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comptime var i: usize = 0;
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inline while (i < Self.len) : (i += 1) {
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const key = comptime Indexer.keyForIndex(i);
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const tag = comptime @tagName(key);
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result.values[i] = @field(init_values, tag);
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}
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return result;
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}
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};
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}
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};
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return IndexedMap(EnumIndexer(E), V, mixin.EnumMapExt);
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}
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/// An array keyed by an enum, backed by a dense array.
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/// If the enum is not dense, a mapping will be constructed from
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/// enum values to dense indices. This type does no dynamic
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/// allocation and can be copied by value.
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pub fn EnumArray(comptime E: type, comptime V: type) type {
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const mixin = struct {
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fn EnumArrayExt(comptime Self: type) type {
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const Indexer = Self.Indexer;
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return struct {
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/// Initializes all values in the enum array
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pub fn init(init_values: EnumFieldStruct(E, V, @as(?V, null))) Self {
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return initDefault(@as(?V, null), init_values);
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}
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/// Initializes values in the enum array, with the specified default.
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pub fn initDefault(comptime default: ?V, init_values: EnumFieldStruct(E, V, default)) Self {
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var result = Self{ .values = undefined };
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comptime var i: usize = 0;
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inline while (i < Self.len) : (i += 1) {
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const key = comptime Indexer.keyForIndex(i);
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const tag = @tagName(key);
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result.values[i] = @field(init_values, tag);
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}
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return result;
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}
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};
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}
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};
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return IndexedArray(EnumIndexer(E), V, mixin.EnumArrayExt);
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}
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/// Pass this function as the Ext parameter to Indexed* if you
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/// do not want to attach any extensions. This parameter was
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/// originally an optional, but optional generic functions
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/// seem to be broken at the moment.
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/// TODO: Once #8169 is fixed, consider switching this param
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/// back to an optional.
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pub fn NoExtension(comptime Self: type) type {
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_ = Self;
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return NoExt;
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}
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const NoExt = struct {};
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/// A set type with an Indexer mapping from keys to indices.
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/// Presence or absence is stored as a dense bitfield. This
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/// type does no allocation and can be copied by value.
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pub fn IndexedSet(comptime I: type, comptime Ext: fn (type) type) type {
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comptime ensureIndexer(I);
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return struct {
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const Self = @This();
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pub usingnamespace Ext(Self);
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/// The indexing rules for converting between keys and indices.
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pub const Indexer = I;
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/// The element type for this set.
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pub const Key = Indexer.Key;
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const BitSet = std.StaticBitSet(Indexer.count);
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/// The maximum number of items in this set.
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pub const len = Indexer.count;
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bits: BitSet = BitSet.initEmpty(),
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/// Returns a set containing all possible keys.
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pub fn initFull() Self {
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return .{ .bits = BitSet.initFull() };
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}
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/// Returns the number of keys in the set.
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pub fn count(self: Self) usize {
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return self.bits.count();
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}
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/// Checks if a key is in the set.
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pub fn contains(self: Self, key: Key) bool {
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return self.bits.isSet(Indexer.indexOf(key));
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}
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/// Puts a key in the set.
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pub fn insert(self: *Self, key: Key) void {
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self.bits.set(Indexer.indexOf(key));
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}
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/// Removes a key from the set.
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pub fn remove(self: *Self, key: Key) void {
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self.bits.unset(Indexer.indexOf(key));
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}
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/// Changes the presence of a key in the set to match the passed bool.
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pub fn setPresent(self: *Self, key: Key, present: bool) void {
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self.bits.setValue(Indexer.indexOf(key), present);
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}
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/// Toggles the presence of a key in the set. If the key is in
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/// the set, removes it. Otherwise adds it.
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pub fn toggle(self: *Self, key: Key) void {
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self.bits.toggle(Indexer.indexOf(key));
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}
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/// Toggles the presence of all keys in the passed set.
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pub fn toggleSet(self: *Self, other: Self) void {
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self.bits.toggleSet(other.bits);
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}
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/// Toggles all possible keys in the set.
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pub fn toggleAll(self: *Self) void {
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self.bits.toggleAll();
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}
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/// Adds all keys in the passed set to this set.
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pub fn setUnion(self: *Self, other: Self) void {
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self.bits.setUnion(other.bits);
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}
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/// Removes all keys which are not in the passed set.
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pub fn setIntersection(self: *Self, other: Self) void {
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self.bits.setIntersection(other.bits);
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}
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/// Returns an iterator over this set, which iterates in
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/// index order. Modifications to the set during iteration
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/// may or may not be observed by the iterator, but will
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/// not invalidate it.
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pub fn iterator(self: *Self) Iterator {
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return .{ .inner = self.bits.iterator(.{}) };
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}
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pub const Iterator = struct {
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inner: BitSet.Iterator(.{}),
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pub fn next(self: *Iterator) ?Key {
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return if (self.inner.next()) |index|
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Indexer.keyForIndex(index)
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else
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null;
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}
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};
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};
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}
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/// A map from keys to values, using an index lookup. Uses a
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/// bitfield to track presence and a dense array of values.
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/// This type does no allocation and can be copied by value.
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pub fn IndexedMap(comptime I: type, comptime V: type, comptime Ext: fn (type) type) type {
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comptime ensureIndexer(I);
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return struct {
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const Self = @This();
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pub usingnamespace Ext(Self);
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/// The index mapping for this map
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pub const Indexer = I;
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/// The key type used to index this map
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pub const Key = Indexer.Key;
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/// The value type stored in this map
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pub const Value = V;
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/// The number of possible keys in the map
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pub const len = Indexer.count;
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const BitSet = std.StaticBitSet(Indexer.count);
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/// Bits determining whether items are in the map
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bits: BitSet = BitSet.initEmpty(),
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/// Values of items in the map. If the associated
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/// bit is zero, the value is undefined.
|
|
values: [Indexer.count]Value = undefined,
|
|
|
|
/// 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];
|
|
}
|
|
|
|
/// 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;
|
|
}
|
|
};
|
|
};
|
|
}
|
|
|
|
/// A dense array of values, using an indexed lookup.
|
|
/// This type does no allocation and can be copied by value.
|
|
pub fn IndexedArray(comptime I: type, comptime V: type, comptime Ext: fn (type) type) type {
|
|
comptime ensureIndexer(I);
|
|
return struct {
|
|
const Self = @This();
|
|
|
|
pub usingnamespace Ext(Self);
|
|
|
|
/// The index mapping for this map
|
|
pub const Indexer = I;
|
|
/// 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;
|
|
|
|
values: [Indexer.count]Value,
|
|
|
|
pub fn initUndefined() Self {
|
|
return Self{ .values = undefined };
|
|
}
|
|
|
|
pub fn initFill(v: Value) Self {
|
|
var self: Self = undefined;
|
|
std.mem.set(Value, &self.values, v);
|
|
return self;
|
|
}
|
|
|
|
/// Returns the value in the array associated with a key.
|
|
pub fn get(self: Self, key: Key) Value {
|
|
return self.values[Indexer.indexOf(key)];
|
|
}
|
|
|
|
/// Returns a pointer to the slot in the array associated with a key.
|
|
pub fn getPtr(self: *Self, key: Key) *Value {
|
|
return &self.values[Indexer.indexOf(key)];
|
|
}
|
|
|
|
/// Returns a const pointer to the slot in the array associated with a key.
|
|
pub fn getPtrConst(self: *const Self, key: Key) *const Value {
|
|
return &self.values[Indexer.indexOf(key)];
|
|
}
|
|
|
|
/// Sets the value in the slot associated with a key.
|
|
pub fn set(self: *Self, key: Key, value: Value) void {
|
|
self.values[Indexer.indexOf(key)] = value;
|
|
}
|
|
|
|
/// Iterates over the items in the array, in index order.
|
|
pub fn iterator(self: *Self) Iterator {
|
|
return .{
|
|
.values = &self.values,
|
|
};
|
|
}
|
|
|
|
/// An entry in the array.
|
|
pub const Entry = struct {
|
|
/// The key associated with this entry.
|
|
/// Modifying this key will not change the array.
|
|
key: Key,
|
|
|
|
/// A pointer to the value in the array associated
|
|
/// with this key. Modifications through this
|
|
/// pointer will modify the underlying data.
|
|
value: *Value,
|
|
};
|
|
|
|
pub const Iterator = struct {
|
|
index: usize = 0,
|
|
values: *[Indexer.count]Value,
|
|
|
|
pub fn next(self: *Iterator) ?Entry {
|
|
const index = self.index;
|
|
if (index < Indexer.count) {
|
|
self.index += 1;
|
|
return Entry{
|
|
.key = Indexer.keyForIndex(index),
|
|
.value = &self.values[index],
|
|
};
|
|
}
|
|
return null;
|
|
}
|
|
};
|
|
};
|
|
}
|
|
|
|
/// Verifies that a type is a valid Indexer, providing a helpful
|
|
/// compile error if not. An Indexer maps a comptime known set
|
|
/// of keys to a dense set of zero-based indices.
|
|
/// The indexer interface must look like this:
|
|
/// ```
|
|
/// struct {
|
|
/// /// The key type which this indexer converts to indices
|
|
/// pub const Key: type,
|
|
/// /// The number of indexes in the dense mapping
|
|
/// pub const count: usize,
|
|
/// /// Converts from a key to an index
|
|
/// pub fn indexOf(Key) usize;
|
|
/// /// Converts from an index to a key
|
|
/// pub fn keyForIndex(usize) Key;
|
|
/// }
|
|
/// ```
|
|
pub fn ensureIndexer(comptime T: type) void {
|
|
comptime {
|
|
if (!@hasDecl(T, "Key")) @compileError("Indexer must have decl Key: type.");
|
|
if (@TypeOf(T.Key) != type) @compileError("Indexer.Key must be a type.");
|
|
if (!@hasDecl(T, "count")) @compileError("Indexer must have decl count: usize.");
|
|
if (@TypeOf(T.count) != usize) @compileError("Indexer.count must be a usize.");
|
|
if (!@hasDecl(T, "indexOf")) @compileError("Indexer.indexOf must be a fn(Key)usize.");
|
|
if (@TypeOf(T.indexOf) != fn (T.Key) usize) @compileError("Indexer must have decl indexOf: fn(Key)usize.");
|
|
if (!@hasDecl(T, "keyForIndex")) @compileError("Indexer must have decl keyForIndex: fn(usize)Key.");
|
|
if (@TypeOf(T.keyForIndex) != fn (usize) T.Key) @compileError("Indexer.keyForIndex must be a fn(usize)Key.");
|
|
}
|
|
}
|
|
|
|
test "std.enums.ensureIndexer" {
|
|
ensureIndexer(struct {
|
|
pub const Key = u32;
|
|
pub const count: usize = 8;
|
|
pub fn indexOf(k: Key) usize {
|
|
return @intCast(usize, k);
|
|
}
|
|
pub fn keyForIndex(index: usize) Key {
|
|
return @intCast(Key, index);
|
|
}
|
|
});
|
|
}
|
|
|
|
fn ascByValue(ctx: void, comptime a: EnumField, comptime b: EnumField) bool {
|
|
_ = ctx;
|
|
return a.value < b.value;
|
|
}
|
|
pub fn EnumIndexer(comptime E: type) type {
|
|
if (!@typeInfo(E).Enum.is_exhaustive) {
|
|
@compileError("Cannot create an enum indexer for a non-exhaustive enum.");
|
|
}
|
|
|
|
const const_fields = std.meta.fields(E);
|
|
var fields = const_fields[0..const_fields.len].*;
|
|
if (fields.len == 0) {
|
|
return struct {
|
|
pub const Key = E;
|
|
pub const count: usize = 0;
|
|
pub fn indexOf(e: E) usize {
|
|
_ = e;
|
|
unreachable;
|
|
}
|
|
pub fn keyForIndex(i: usize) E {
|
|
_ = i;
|
|
unreachable;
|
|
}
|
|
};
|
|
}
|
|
std.sort.sort(EnumField, &fields, {}, ascByValue);
|
|
const min = fields[0].value;
|
|
const max = fields[fields.len - 1].value;
|
|
const fields_len = fields.len;
|
|
if (max - min == fields.len - 1) {
|
|
return struct {
|
|
pub const Key = E;
|
|
pub const count = fields_len;
|
|
pub fn indexOf(e: E) usize {
|
|
return @intCast(usize, @enumToInt(e) - min);
|
|
}
|
|
pub fn keyForIndex(i: usize) E {
|
|
// TODO fix addition semantics. This calculation
|
|
// gives up some safety to avoid artificially limiting
|
|
// the range of signed enum values to max_isize.
|
|
const enum_value = if (min < 0) @bitCast(isize, i) +% min else i + min;
|
|
return @intToEnum(E, @intCast(std.meta.Tag(E), enum_value));
|
|
}
|
|
};
|
|
}
|
|
|
|
const keys = valuesFromFields(E, &fields);
|
|
|
|
return struct {
|
|
pub const Key = E;
|
|
pub const count = fields_len;
|
|
pub fn indexOf(e: E) usize {
|
|
for (keys) |k, i| {
|
|
if (k == e) return i;
|
|
}
|
|
unreachable;
|
|
}
|
|
pub fn keyForIndex(i: usize) E {
|
|
return keys[i];
|
|
}
|
|
};
|
|
}
|
|
|
|
test "std.enums.EnumIndexer dense zeroed" {
|
|
const E = enum(u2) { b = 1, a = 0, c = 2 };
|
|
const Indexer = EnumIndexer(E);
|
|
ensureIndexer(Indexer);
|
|
try testing.expectEqual(E, Indexer.Key);
|
|
try testing.expectEqual(@as(usize, 3), Indexer.count);
|
|
|
|
try testing.expectEqual(@as(usize, 0), Indexer.indexOf(.a));
|
|
try testing.expectEqual(@as(usize, 1), Indexer.indexOf(.b));
|
|
try testing.expectEqual(@as(usize, 2), Indexer.indexOf(.c));
|
|
|
|
try testing.expectEqual(E.a, Indexer.keyForIndex(0));
|
|
try testing.expectEqual(E.b, Indexer.keyForIndex(1));
|
|
try testing.expectEqual(E.c, Indexer.keyForIndex(2));
|
|
}
|
|
|
|
test "std.enums.EnumIndexer dense positive" {
|
|
const E = enum(u4) { c = 6, a = 4, b = 5 };
|
|
const Indexer = EnumIndexer(E);
|
|
ensureIndexer(Indexer);
|
|
try testing.expectEqual(E, Indexer.Key);
|
|
try testing.expectEqual(@as(usize, 3), Indexer.count);
|
|
|
|
try testing.expectEqual(@as(usize, 0), Indexer.indexOf(.a));
|
|
try testing.expectEqual(@as(usize, 1), Indexer.indexOf(.b));
|
|
try testing.expectEqual(@as(usize, 2), Indexer.indexOf(.c));
|
|
|
|
try testing.expectEqual(E.a, Indexer.keyForIndex(0));
|
|
try testing.expectEqual(E.b, Indexer.keyForIndex(1));
|
|
try testing.expectEqual(E.c, Indexer.keyForIndex(2));
|
|
}
|
|
|
|
test "std.enums.EnumIndexer dense negative" {
|
|
const E = enum(i4) { a = -6, c = -4, b = -5 };
|
|
const Indexer = EnumIndexer(E);
|
|
ensureIndexer(Indexer);
|
|
try testing.expectEqual(E, Indexer.Key);
|
|
try testing.expectEqual(@as(usize, 3), Indexer.count);
|
|
|
|
try testing.expectEqual(@as(usize, 0), Indexer.indexOf(.a));
|
|
try testing.expectEqual(@as(usize, 1), Indexer.indexOf(.b));
|
|
try testing.expectEqual(@as(usize, 2), Indexer.indexOf(.c));
|
|
|
|
try testing.expectEqual(E.a, Indexer.keyForIndex(0));
|
|
try testing.expectEqual(E.b, Indexer.keyForIndex(1));
|
|
try testing.expectEqual(E.c, Indexer.keyForIndex(2));
|
|
}
|
|
|
|
test "std.enums.EnumIndexer sparse" {
|
|
const E = enum(i4) { a = -2, c = 6, b = 4 };
|
|
const Indexer = EnumIndexer(E);
|
|
ensureIndexer(Indexer);
|
|
try testing.expectEqual(E, Indexer.Key);
|
|
try testing.expectEqual(@as(usize, 3), Indexer.count);
|
|
|
|
try testing.expectEqual(@as(usize, 0), Indexer.indexOf(.a));
|
|
try testing.expectEqual(@as(usize, 1), Indexer.indexOf(.b));
|
|
try testing.expectEqual(@as(usize, 2), Indexer.indexOf(.c));
|
|
|
|
try testing.expectEqual(E.a, Indexer.keyForIndex(0));
|
|
try testing.expectEqual(E.b, Indexer.keyForIndex(1));
|
|
try testing.expectEqual(E.c, Indexer.keyForIndex(2));
|
|
}
|