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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};
const n = try self.reader.read(buffer[0..]);
if (n == 1) {
return buffer[0];
}
return error.IOError;
}
test "characterInput" {
const 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" {
const 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 {
var vv: u8 = '?';
if (v >= 0 and v <= 255) {
vv = @intCast(v);
}
try self.writer.print("{c}", .{vv});
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,
};
}
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