Change Allocator to use interface style

src/core/io.zig

@@ -3,9 +3,9 @@ const stack = @import("./stack.zig");
 const std = @import("std");
 
 ///
-/// Closure for allocating, reallocating, and deallocating dynamic memory resources through itself.
 ///
-pub const Allocator = meta.BiFunction(56, ?[]u8, usize, AllocationError![]u8);
+///
+pub const Allocator = std.mem.Allocator;
 
 ///
 /// File-system agnostic abstraction for manipulating a file.
@@ -203,7 +203,7 @@ pub fn equals(comptime Element: type, this: []const Element, that: []const Eleme
     return true;
 }
 
-test "Equivalence of bytes" {
+test "Memory buffers equal" {
     const bytes_sequence = &.{69, 42, 0};
     const testing = std.testing;
 
@@ -255,11 +255,3 @@ test "Null writing" {
         try testing.expectEqual(nullWriter().apply(sequence), sequence.len);
     }
 }
-
-///
-/// Applies the singular `byte` to `writer`, returning `true` if it was successfully written,
-/// otherwise `false`.
-///
-pub fn writeByte(writer: *Writer, byte: u8) bool {
-    return (writer.apply(std.mem.asBytes(&byte)) != 0);
-}

src/core/meta.zig

@@ -48,20 +48,20 @@ pub fn BiFunction(comptime captures_size: usize, comptime A: type,
                 @compileError("`captures` must be smaller than or equal to " ++
                     std.fmt.comptimePrint("{d}", .{captures_size}) ++ " bytes");
 
-            const captures_align = @alignOf(Captures);
-
             var function = Self{
                 .context = undefined,
 
                 .applyErased = struct {
-                    fn do(erased: *anyopaque, a: A, b: B) Out {
+                    fn applyErased(erased: *anyopaque, a: A, b: B) Out {
-                        return call(@ptrCast(*Captures, @alignCast(
+                        return call(if (Captures == void) {} else @ptrCast(*Captures,
-                            captures_align, erased)).*, a, b);
+                            @alignCast(@alignOf(Captures), erased)).*, a, b);
                     }
-                }.do,
+                }.applyErased,
             };
 
-            @ptrCast(*Captures, @alignCast(captures_align, &function.context)).* = captures;
+            if (captures != {}) {
+                @ptrCast(*Captures, @alignCast(@alignOf(Captures), &function.context)).* = captures;
+            }
 
             return function;
         }
@@ -108,11 +108,11 @@ pub fn Function(comptime captures_size: usize, comptime In: type, comptime Out:
                 .context = undefined,
 
                 .applyErased = struct {
-                    fn do(erased: *anyopaque, input: In) Out {
+                    fn applyErased(erased: *anyopaque, input: In) Out {
-                        return call(@ptrCast(*Captures, @alignCast(
+                        return call(if (Captures == void) {} else @ptrCast(*Captures,
-                            captures_align, erased)).*, input);
+                            @alignCast(@alignOf(Captures), erased)).*, input);
                     }
-                }.do,
+                }.applyErased,
             };
 
             @ptrCast(*Captures, @alignCast(captures_align, &function.context)).* = captures;

src/core/table.zig

@@ -1,4 +1,4 @@
-const std = @import("std");
+const io = @import("./io.zig");
 
 ///
 /// Returns a hash-backed table type of `Value`s indexed by `Key` and using `key_context` as the key
@@ -7,7 +7,7 @@ const std = @import("std");
 pub fn Hashed(comptime Key: type, comptime Value: type,
     comptime key_context: KeyContext(Key)) type {
 
-    const Allocator = std.mem.Allocator;
+    const Allocator = io.Allocator;
 
     return struct {
         allocator: Allocator,
@@ -44,11 +44,13 @@ pub fn Hashed(comptime Key: type, comptime Value: type,
         ///
         /// Initializes a [Self] using `allocator` as the memory allocation strategy.
         ///
-        /// Returns a new [Self] value or an [Allocator.Error] if initializing failed.
+        /// Returns a new [Self] value or an [io.Allocator.Error] if initializing failed.
         ///
         pub fn init(allocator: Allocator) Allocator.Error!Self {
+            const initial_capacity = 4;
+
             return Self{
-                .buckets = try allocator.alloc(Bucket, 4),
+                .buckets = try allocator.alloc(Bucket, initial_capacity),
                 .filled = 0,
                 .allocator = allocator,
                 .load_limit = 0.75,
@@ -158,7 +160,7 @@ pub fn Hashed(comptime Key: type, comptime Value: type,
 /// [InsertError.KeyExists] occurs when an insertion was attempted on a table with a matching key
 /// already present.
 ///
-pub const InsertError = std.mem.Allocator.Error || error {
+pub const InsertError = io.Allocator.Error || error {
     KeyExists,
 };
 
@@ -173,14 +175,27 @@ pub fn KeyContext(comptime Key: type) type {
     };
 }
 
-test "Hashed table manipulation with bytes context" {
+///
-    const testing = std.testing;
+/// A [KeyContext] for dealing with string literal (i.e. []const u8) values.
-    const io = @import("./io.zig");
+///
+/// **Note** that, while lightweight, this context should only be considered safe to use with string
+/// literals or variables pointing to string literals - as the [KeyContext] does not take ownership
+/// of its keys beyond copying the reference.
+///
+pub const string_literal_context = KeyContext([]const u8){
+    .hash = io.hashBytes,
 
-    var table = try Hashed([]const u8, u32, .{
+    .equals = struct {
-        .equals = io.equalsBytes,
+        fn stringsEqual(this: []const u8, that: []const u8) bool {
-        .hash = io.hashBytes,
+            return io.equals(u8, this, that);
-    }).init(testing.allocator);
+        }
+    }.stringsEqual,
+};
+
+test "Hash table manipulation with string literal context" {
+    const testing = @import("std").testing;
+
+    var table = try Hashed([]const u8, u32, string_literal_context).init(testing.allocator);
 
     defer table.deinit();