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const std = @import("std");
pub fn Context(readerType: anytype, writerType: anytype) type {
return struct {
reader: readerType,
writer: writerType,
lastChar: ?i64 = null,
allocator: std.mem.Allocator,
const Self = @This();
pub fn deinit(self: *Self) void {
self.allocator.destroy(self);
}
pub fn init(allocator: std.mem.Allocator, reader: readerType, writer: writerType) !*Self {
var c = try allocator.create(Self);
c.allocator = allocator;
c.reader = reader;
c.writer = writer;
return c;
}
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 = try context(std.testing.allocator, stdin, stdout);
defer ioContext.deinit();
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 = try context(std.testing.allocator, stdin, stdout);
defer ioContext.deinit();
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(allocator: std.mem.Allocator, reader: anytype, writer: anytype) !*Context(@TypeOf(reader), @TypeOf(writer)) {
return Context(@TypeOf(reader), @TypeOf(writer)).init(allocator, reader, writer);
}
test "all" {
std.testing.refAllDecls(@This());
}
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