Simple text scanner like Java for Zig. For competitive programming.

scanner.zig

const std = @import("std");

pub const Scanner = struct {
    const Self = @This();
    const stdin = std.io.getStdIn();
    var buffered_reader = std.io.bufferedReader(stdin.reader());
    var reader = buffered_reader.reader();

    buffer: [65536]u8 = undefined,

    pub fn init() Self {
        return Self{};
    }
    pub fn next(self: *Self) []const u8 {
        var fbs = std.io.fixedBufferStream(&self.buffer);
        const writer = fbs.writer();
        for (0..fbs.buffer.len) |_| {
            const byte: u8 = reader.readByte() catch unreachable;
            if (std.ascii.isWhitespace(byte)) {
                break;
            }
            writer.writeByte(byte) catch unreachable;
        }
        const output = fbs.getWritten();
        self.buffer[output.len] = ' '; // emulating old behaviour
        return output;
    }
    pub fn nextOwn(self: *Self, allocator: std.mem.Allocator) []const u8 {
        return allocator.dupe(u8, self.next()) catch unreachable;
    }
    pub fn nextLine(self: *Self) []const u8 {
        const line = reader.readUntilDelimiterOrEof(&self.buffer, '\n') catch unreachable;
        if (@import("builtin").os.tag == .windows) {
            return std.mem.trimRight(u8, line.?, "\r");
        } else {
            return line.?;
        }
    }
    pub fn nextLineOwn(self: *Self, allocator: std.mem.Allocator) []const u8 {
        return allocator.dupe(u8, self.nextLine()) catch unreachable;
    }
    pub fn nextUsize(self: *Self) usize {
        return std.fmt.parseInt(usize, self.next(), 10) catch unreachable;
    }
    pub fn nextInt(self: *Self, comptime T: type) T {
        return std.fmt.parseInt(T, self.next(), 10) catch unreachable;
    }
    pub fn nextFloat(self: *Self, comptime T: type) T {
        return std.fmt.parseFloat(T, self.next()) catch unreachable;
    }
};