const std = @import("std"); pub fn Context(comptime readerType: anytype, comptime writerType: anytype) type { return struct { reader: readerType, writer: writerType, lastChar: ?i64 = null, const Self = @This(); pub fn characterInput(self: *Self) !i64 { if (self.lastChar) |c| { self.lastChar = null; return c; } var buffer = [_]u8{0}; var n = try self.reader.read(buffer[0..]); if (n == 1) { return buffer[0]; } return error.IOError; } test "characterInput" { var stdin = std.io.fixedBufferStream("ab0"); var stdout = std.ArrayList(u8).init(std.testing.allocator); defer stdout.deinit(); var ioContext = context(stdin, stdout); try std.testing.expectEqual(try ioContext.characterInput(), 'a'); try std.testing.expectEqual(try ioContext.characterInput(), 'b'); try std.testing.expectEqual(try ioContext.characterInput(), '0'); try std.testing.expectEqual(ioContext.characterInput(), error.IOError); } pub fn decimalInput(self: *Self) !i64 { var result: i64 = undefined; while (true) { // Fist we need to find the next numeric char const c = self.characterInput() catch return error.IOError; if (c >= '0' and c <= '9') { result = c - '0'; break; } } while (true) { // then we read until we encounter a non numeric char const c = self.characterInput() catch break; if (c >= '0' and c <= '9') { result = result * 10 + c - '0'; } else { self.lastChar = c; break; } } return result; } test "decimalInput" { var stdin = std.io.fixedBufferStream("1 234abc5d6ef"); var stdout = std.ArrayList(u8).init(std.testing.allocator); defer stdout.deinit(); var ioContext = context(stdin, stdout); try std.testing.expectEqual(try ioContext.decimalInput(), 1); try std.testing.expectEqual(try ioContext.decimalInput(), 234); try std.testing.expectEqual(try ioContext.decimalInput(), 5); try std.testing.expectEqual(try ioContext.decimalInput(), 6); try std.testing.expectEqual(ioContext.decimalInput(), error.IOError); } pub fn characterOutput(self: Self, v: i64) !void { try self.writer.print("{c}", .{@intCast(u8, v)}); return; } pub fn decimalOutput(self: Self, v: i64) !void { try self.writer.print("{d}", .{v}); return; } }; } pub fn context(reader: anytype, writer: anytype) Context(@TypeOf(reader), @TypeOf(writer)) { return .{ .reader = reader, .writer = writer, }; } test "all" { std.testing.refAllDecls(@This()); }