Replace UTF-8 compares with standard memory compares

This commit is contained in:
kayomn 2022-10-17 15:48:56 +01:00
parent 9f411025a7
commit 033227b243
3 changed files with 44 additions and 57 deletions

View File

@ -286,6 +286,43 @@ pub const Writer = struct {
}
};
///
/// Returns `true` if `this_bytes` is the same length and contains the same data as `that_bytes`,
/// otherwise `false`.
///
pub fn equalsBytes(this_bytes: []const u8, that_bytes: []const u8) bool {
return std.mem.eql(u8, this_bytes, that_bytes);
}
test "Equivalence of bytes" {
const bytes_sequence = &.{69, 42, 0};
const testing = std.testing;
try testing.expect(equalsBytes(bytes_sequence, bytes_sequence));
try testing.expect(!equalsBytes(bytes_sequence, &.{69, 42}));
}
///
/// Returns a deterministic hash code compiled from each byte in `bytes`.
///
/// **Note** that this operation has `O(n)` time complexity.
///
pub fn hashBytes(bytes: []const u8) usize {
var hash = @as(usize, 5381);
for (bytes) |byte| hash = ((hash << 5) + hash) + byte;
return hash;
}
test "Hashing bytes" {
const bytes_sequence = &.{69, 42, 0};
const testing = std.testing;
try testing.expect(hashBytes(bytes_sequence) == hashBytes(bytes_sequence));
try testing.expect(hashBytes(bytes_sequence) != hashBytes(&.{69, 42}));
}
///
/// Writer that silently throws consumed data away and never fails.
///

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@ -173,35 +173,14 @@ pub fn KeyContext(comptime Key: type) type {
};
}
///
/// Tests if the contents of `this_string` lexically equals the contents of `that_string`.
///
fn equalsString(this_string: []const u8, that_string: []const u8) bool {
return std.mem.eql(u8, this_string, that_string);
}
///
/// Hashes `string` into a hash value of `usize`.
///
fn hashString(string: []const u8) usize {
var hash = @as(usize, 5381);
for (string) |byte| hash = ((hash << 5) + hash) + byte;
return hash;
}
///
/// A [KeyContext] for handling `[]const u8` types.
///
pub const string_context = KeyContext([]const u8){
.hash = hashString,
.equals = equalsString,
};
test "Hashed table manipulation with string context" {
test "Hashed table manipulation with bytes context" {
const testing = std.testing;
var table = try Hashed([]const u8, u32, string_context).init(testing.allocator);
const io = @import("./io.zig");
var table = try Hashed([]const u8, u32, .{
.equals = io.equalsBytes,
.hash = io.hashBytes,
}).init(testing.allocator);
defer table.deinit();

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@ -1,29 +0,0 @@
const std = @import("std");
const table = @import("./table.zig");
///
/// Tests if the contents of `this_utf8_sequence` lexically equals the contents of
/// `that_utf8_sequence`.
///
pub fn equals(this_utf8_sequence: []const u8, that_utf8_sequence: []const u8) bool {
return std.mem.eql(u8, this_utf8_sequence, that_utf8_sequence);
}
///
/// Returns a deterministic hash for `utf8_sequence`.
///
pub fn hash(utf8_sequence: []const u8) usize {
var utf8_hash = @as(usize, 5381);
for (utf8_sequence) |utf8_code| utf8_hash = ((utf8_hash << 5) + utf8_hash) + utf8_code;
return utf8_hash;
}
///
/// A [table.KeyContext] for handling UTF-8 character sequences.
///
pub const key_context = table.KeyContext([]const u8){
.hash = hash,
.equals = equals,
};