Add additional memory utils to core module

src/core/io.zig

@@ -7,102 +7,6 @@ const std = @import("std");
 ///
 pub const Allocator = std.mem.Allocator;
 
-///
-/// File-system agnostic abstraction for manipulating a file.
-///
-pub const FileAccess = struct {
-    context: *anyopaque,
-    implementation: *const Implementation,
-
-    ///
-    /// Provides a set of implementation-specific behaviors to a [FileAccess] instance.
-    ///
-    pub const Implementation = struct {
-        close: fn (*anyopaque) void,
-        queryCursor: fn (*anyopaque) Error!u64,
-        queryLength: fn (*anyopaque) Error!u64,
-        read: fn (*anyopaque, []u8) Error!usize,
-        seek: fn (*anyopaque, u64) Error!void,
-        seekToEnd: fn (*anyopaque) Error!void,
-        skip: fn (*anyopaque, i64) Error!void,
-    };
-
-    ///
-    /// [Error.FileInaccessible] is a generic catch-all for a [FileAccess] reference no longer
-    /// pointing to a file or the file becomming invalid for whatever reason.
-    ///
-    pub const Error = error {
-        FileInaccessible,
-    };
-
-    ///
-    /// Close the file referenced by `file_access` on the main thread, invalidating the reference to
-    /// it and releasing any associated resources.
-    ///
-    /// Freeing an invalid `file_access` has no effect on the file and logs a warning over the
-    /// wasted effort.
-    ///
-    pub fn close(file_access: FileAccess) void {
-        return file_access.implementation.close(file_access.context);
-    }
-
-    ///
-    /// Attempts to query the current cursor position for the file referenced by `file_access`.
-    ///
-    /// Returns the number of bytes into the file that the cursor is relative to its beginning or a
-    /// [Error] on failure.
-    ///
-    pub fn queryCursor(file_access: FileAccess) Error!u64 {
-        return file_access.implementation.queryCursor(file_access.context);
-    }
-
-    ///
-    /// Attempts to query the current length for the file referenced by `file_access`.
-    ///
-    /// Returns the current length of the file at the time of the operation or a [Error] if the file
-    /// failed to be queried.
-    ///
-    pub fn queryLength(file_access: FileAccess) Error!u64 {
-        return file_access.implementation.queryLength(file_access.context);
-    }
-
-    ///
-    /// Attempts to read `file_access` from the its current position into `buffer`.
-    ///
-    /// Returns the number of bytes that were available to be read, otherwise an [Error] on failure.
-    ///
-    pub fn read(file_access: FileAccess, buffer: []u8) Error!usize {
-        return file_access.implementation.read(file_access.context, buffer);
-    }
-
-    ///
-    /// Attempts to seek `file_access` from the beginning of the file to `cursor` bytes.
-    ///
-    /// Returns [Error] on failure.
-    ///
-    pub fn seek(file_access: FileAccess, cursor: u64) Error!void {
-        return file_access.implementation.seek(file_access.context, cursor);
-    }
-
-    ///
-    /// Attempts to seek `file_access` to the end of the file.
-    ///
-    /// Returns [Error] on failure.
-    ///
-    pub fn seekToEnd(file_access: FileAccess) Error!void {
-        return file_access.implementation.seekToEnd(file_access.context);
-    }
-
-    ///
-    /// Attempts to seek `file_access` by `offset` from the current file position.
-    ///
-    /// Returns [Error] on failure;
-    ///
-    pub fn skip(file_access: FileAccess, offset: i64) Error!void {
-        return file_access.implementation.skip(file_access.context, offset);
-    }
-};
-
 ///
 /// Closure that captures a reference to readable resources like block devices, memory buffers,
 /// network sockets, and more.
@@ -161,7 +65,7 @@ test "Spliterating text" {
         var index = @as(usize, 0);
 
         while (spliterator.next()) |split| : (index += 1) {
-            try testing.expect(std.mem.eql(u8, split, components[index]));
+            try testing.expect(equals(u8, split, components[index]));
         }
     }
 
@@ -176,7 +80,7 @@ test "Spliterating text" {
         var index = @as(usize, 0);
 
         while (spliterator.next()) |split| : (index += 1) {
-            try testing.expect(std.mem.eql(u8, split, components[index]));
+            try testing.expect(equals(u8, split, components[index]));
         }
     }
 }
@@ -209,7 +113,7 @@ test "Check memory begins with" {
 ///
 /// **Note** that passing a slice will convert it to a byte slice.
 ///
-pub fn bytes(pointer: anytype) switch (@typeInfo(@TypeOf(pointer))) {
+pub fn bytesOf(pointer: anytype) switch (@typeInfo(@TypeOf(pointer))) {
     .Pointer => |info| if (info.is_const) []const u8 else []u8,
     else => @compileError("`pointer` must be a pointer type"),
 } {
@@ -233,7 +137,35 @@ test "Bytes of types" {
 
     var foo: u32 = 10;
 
-    testing.expectEqual(bytes(&foo), 0x0a);
+    testing.expectEqual(bytesOf(&foo), 0x0a);
+}
+
+///
+/// Compares `this` to `that`, returning the difference between the first byte deviation in the two
+/// sequences, otherwise `0` if they are identical.
+///
+pub fn compareBytes(this: []const u8, that: []const u8) isize {
+    var cursor: usize = 0;
+
+    while (cursor != this.len) : (cursor += 1) {
+        const this_byte = this[cursor];
+
+        if (cursor != that.len) return this_byte;
+
+        const that_byte = that[cursor];
+
+        if (this_byte != that_byte) return (this_byte - that_byte);
+    }
+
+    return 0;
+}
+
+test "Compare bytes" {
+    const testing = std.testing;
+
+    try testing.expectEquals(compareBytes(&.{69, 42, 0}, &.{69, 42, 0}), 0);
+    try testing.expectEquals(compareBytes(&.{69, 42, 0}, &.{69, 42}), 42);
+    try testing.expectEquals(compareBytes(&.{69, 42}, &.{69, 42, 0}), -42);
 }
 
 ///
@@ -243,11 +175,9 @@ test "Bytes of types" {
 pub fn equals(comptime Element: type, this: []const Element, that: []const Element) bool {
     if (this.len != that.len) return false;
 
-    {
     var i = std.mem.zeroes(usize);
 
     while (i < this.len) : (i += 1) if (this[i] != that[i]) return false;
-    }
 
     return true;
 }