MultiSliceView

const MultiSliceView = struct

File

Code

const MultiSliceView = struct {
    slices: [3][]const u8,
    offsets: [4]usize,

    fn init(s1: []const u8, s2: []const u8, s3: []const u8) MultiSliceView {
        return .{
            .slices = .{ s1, s2, s3 },
            .offsets = .{
                0,
                s1.len,
                s1.len + s2.len,
                s1.len + s2.len + s3.len,
            },
        };
    }

    fn totalLen(self: *const MultiSliceView) usize {
        return self.offsets[3];
    }

    /// Get byte at position (zero-copy)
    fn getByte(self: *const MultiSliceView, pos: usize) u8 {
        for (0..3) |i| {
            if (pos >= self.offsets[i] and pos < self.offsets[i + 1]) {
                return self.slices[i][pos - self.offsets[i]];
            }
        }
        unreachable;
    }

    /// Try to get a contiguous slice [start..end) - returns null if spans boundaries
    fn tryGetSlice(self: *const MultiSliceView, start: usize, end: usize) ?[]const u8 {
        for (0..3) |i| {
            if (start >= self.offsets[i] and end <= self.offsets[i + 1]) {
                const local_start = start - self.offsets[i];
                const local_end = end - self.offsets[i];
                return self.slices[i][local_start..local_end];
            }
        }
        return null;
    }

    /// Copy range [start..end) to buffer (used when slice spans boundaries)
    fn copyRange(self: *const MultiSliceView, start: usize, end: usize, buffer: []u8) void {
        var pos: usize = 0;
        for (start..end) |i| {
            buffer[pos] = self.getByte(i);
            pos += 1;
        }
    }
}