1
   2
   3
   4
   5
   6
   7
   8
   9
  10
  11
  12
  13
  14
  15
  16
  17
  18
  19
  20
  21
  22
  23
  24
  25
  26
  27
  28
  29
  30
  31
  32
  33
  34
  35
  36
  37
  38
  39
  40
  41
  42
  43
  44
  45
  46
  47
  48
  49
  50
  51
  52
  53
  54
  55
  56
  57
  58
  59
  60
  61
  62
  63
  64
  65
  66
  67
  68
  69
  70
  71
  72
  73
  74
  75
  76
  77
  78
  79
  80
  81
  82
  83
  84
  85
  86
  87
  88
  89
  90
  91
  92
  93
  94
  95
  96
  97
  98
  99
 100
 101
 102
 103
 104
 105
 106
 107
 108
 109
 110
 111
 112
 113
 114
 115
 116
 117
 118
 119
 120
 121
 122
 123
 124
 125
 126
 127
 128
 129
 130
 131
 132
 133
 134
 135
 136
 137
 138
 139
 140
 141
 142
 143
 144
 145
 146
 147
 148
 149
 150
 151
 152
 153
 154
 155
 156
 157
 158
 159
 160
 161
 162
 163
 164
 165
 166
 167
 168
 169
 170
 171
 172
 173
 174
 175
 176
 177
 178
 179
 180
 181
 182
 183
 184
 185
 186
 187
 188
 189
 190
 191
 192
 193
 194
 195
 196
 197
 198
 199
 200
 201
 202
 203
 204
 205
 206
 207
 208
 209
 210
 211
 212
 213
 214
 215
 216
 217
 218
 219
 220
 221
 222
 223
 224
 225
 226
 227
 228
 229
 230
 231
 232
 233
 234
 235
 236
 237
 238
 239
 240
 241
 242
 243
 244
 245
 246
 247
 248
 249
 250
 251
 252
 253
 254
 255
 256
 257
 258
 259
 260
 261
 262
 263
 264
 265
 266
 267
 268
 269
 270
 271
 272
 273
 274
 275
 276
 277
 278
 279
 280
 281
 282
 283
 284
 285
 286
 287
 288
 289
 290
 291
 292
 293
 294
 295
 296
 297
 298
 299
 300
 301
 302
 303
 304
 305
 306
 307
 308
 309
 310
 311
 312
 313
 314
 315
 316
 317
 318
 319
 320
 321
 322
 323
 324
 325
 326
 327
 328
 329
 330
 331
 332
 333
 334
 335
 336
 337
 338
 339
 340
 341
 342
 343
 344
 345
 346
 347
 348
 349
 350
 351
 352
 353
 354
 355
 356
 357
 358
 359
 360
 361
 362
 363
 364
 365
 366
 367
 368
 369
 370
 371
 372
 373
 374
 375
 376
 377
 378
 379
 380
 381
 382
 383
 384
 385
 386
 387
 388
 389
 390
 391
 392
 393
 394
 395
 396
 397
 398
 399
 400
 401
 402
 403
 404
 405
 406
 407
 408
 409
 410
 411
 412
 413
 414
 415
 416
 417
 418
 419
 420
 421
 422
 423
 424
 425
 426
 427
 428
 429
 430
 431
 432
 433
 434
 435
 436
 437
 438
 439
 440
 441
 442
 443
 444
 445
 446
 447
 448
 449
 450
 451
 452
 453
 454
 455
 456
 457
 458
 459
 460
 461
 462
 463
 464
 465
 466
 467
 468
 469
 470
 471
 472
 473
 474
 475
 476
 477
 478
 479
 480
 481
 482
 483
 484
 485
 486
 487
 488
 489
 490
 491
 492
 493
 494
 495
 496
 497
 498
 499
 500
 501
 502
 503
 504
 505
 506
 507
 508
 509
 510
 511
 512
 513
 514
 515
 516
 517
 518
 519
 520
 521
 522
 523
 524
 525
 526
 527
 528
 529
 530
 531
 532
 533
 534
 535
 536
 537
 538
 539
 540
 541
 542
 543
 544
 545
 546
 547
 548
 549
 550
 551
 552
 553
 554
 555
 556
 557
 558
 559
 560
 561
 562
 563
 564
 565
 566
 567
 568
 569
 570
 571
 572
 573
 574
 575
 576
 577
 578
 579
 580
 581
 582
 583
 584
 585
 586
 587
 588
 589
 590
 591
 592
 593
 594
 595
 596
 597
 598
 599
 600
 601
 602
 603
 604
 605
 606
 607
 608
 609
 610
 611
 612
 613
 614
 615
 616
 617
 618
 619
 620
 621
 622
 623
 624
 625
 626
 627
 628
 629
 630
 631
 632
 633
 634
 635
 636
 637
 638
 639
 640
 641
 642
 643
 644
 645
 646
 647
 648
 649
 650
 651
 652
 653
 654
 655
 656
 657
 658
 659
 660
 661
 662
 663
 664
 665
 666
 667
 668
 669
 670
 671
 672
 673
 674
 675
 676
 677
 678
 679
 680
 681
 682
 683
 684
 685
 686
 687
 688
 689
 690
 691
 692
 693
 694
 695
 696
 697
 698
 699
 700
 701
 702
 703
 704
 705
 706
 707
 708
 709
 710
 711
 712
 713
 714
 715
 716
 717
 718
 719
 720
 721
 722
 723
 724
 725
 726
 727
 728
 729
 730
 731
 732
 733
 734
 735
 736
 737
 738
 739
 740
 741
 742
 743
 744
 745
 746
 747
 748
 749
 750
 751
 752
 753
 754
 755
 756
 757
 758
 759
 760
 761
 762
 763
 764
 765
 766
 767
 768
 769
 770
 771
 772
 773
 774
 775
 776
 777
 778
 779
 780
 781
 782
 783
 784
 785
 786
 787
 788
 789
 790
 791
 792
 793
 794
 795
 796
 797
 798
 799
 800
 801
 802
 803
 804
 805
 806
 807
 808
 809
 810
 811
 812
 813
 814
 815
 816
 817
 818
 819
 820
 821
 822
 823
 824
 825
 826
 827
 828
 829
 830
 831
 832
 833
 834
 835
 836
 837
 838
 839
 840
 841
 842
 843
 844
 845
 846
 847
 848
 849
 850
 851
 852
 853
 854
 855
 856
 857
 858
 859
 860
 861
 862
 863
 864
 865
 866
 867
 868
 869
 870
 871
 872
 873
 874
 875
 876
 877
 878
 879
 880
 881
 882
 883
 884
 885
 886
 887
 888
 889
 890
 891
 892
 893
 894
 895
 896
 897
 898
 899
 900
 901
 902
 903
 904
 905
 906
 907
 908
 909
 910
 911
 912
 913
 914
 915
 916
 917
 918
 919
 920
 921
 922
 923
 924
 925
 926
 927
 928
 929
 930
 931
 932
 933
 934
 935
 936
 937
 938
 939
 940
 941
 942
 943
 944
 945
 946
 947
 948
 949
 950
 951
 952
 953
 954
 955
 956
 957
 958
 959
 960
 961
 962
 963
 964
 965
 966
 967
 968
 969
 970
 971
 972
 973
 974
 975
 976
 977
 978
 979
 980
 981
 982
 983
 984
 985
 986
 987
 988
 989
 990
 991
 992
 993
 994
 995
 996
 997
 998
 999
1000
1001
1002
1003
1004
1005
1006
1007
1008
1009
1010
1011
1012
1013
1014
1015
1016
1017
1018
1019
1020
1021
1022
1023
1024
1025
1026
1027
1028
1029
1030
use std::collections::{BTreeMap, BTreeSet};
use std::collections::{HashMap, HashSet};
use std::convert::From;
use std::error;
use std::fmt;
use std::hash::Hash;
use std::io;
use std::str::{Utf8Error, from_utf8};

use futures::Future;

#[cfg(feature = "with-rustc-json")]
use serialize::json;

/// Helper enum that is used in some situations to describe
/// the behavior of arguments in a numeric context.
#[derive(PartialEq, Eq, Clone, Debug, Copy)]
pub enum NumericBehavior {
    NonNumeric,
    NumberIsInteger,
    NumberIsFloat,
}

/// An enum of all error kinds.
#[derive(PartialEq, Eq, Copy, Clone, Debug)]
pub enum ErrorKind {
    /// The server generated an invalid response.
    ResponseError,
    /// The authentication with the server failed.
    AuthenticationFailed,
    /// Operation failed because of a type mismatch.
    TypeError,
    /// A script execution was aborted.
    ExecAbortError,
    /// The server cannot response because it's loading a dump.
    BusyLoadingError,
    /// A script that was requested does not actually exist.
    NoScriptError,
    /// An error that was caused because the parameter to the
    /// client were wrong.
    InvalidClientConfig,
    /// This kind is returned if the redis error is one that is
    /// not native to the system.  This is usually the case if
    /// the cause is another error.
    IoError,
    /// An extension error.  This is an error created by the server
    /// that is not directly understood by the library.
    ExtensionError,
}

/// Internal low-level redis value enum.
#[derive(PartialEq, Eq, Clone)]
pub enum Value {
    /// A nil response from the server.
    Nil,
    /// An integer response.  Note that there are a few situations
    /// in which redis actually returns a string for an integer which
    /// is why this library generally treats integers and strings
    /// the same for all numeric responses.
    Int(i64),
    /// An arbitary binary data.
    Data(Vec<u8>),
    /// A bulk response of more data.  This is generally used by redis
    /// to express nested structures.
    Bulk(Vec<Value>),
    /// A status response.
    Status(String),
    /// A status response which represents the string "OK".
    Okay,
}

/// Values are generally not used directly unless you are using the
/// more low level functionality in the library.  For the most part
/// this is hidden with the help of the `FromRedisValue` trait.
///
/// While on the redis protocol there is an error type this is already
/// separated at an early point so the value only holds the remaining
/// types.
impl Value {
    /// Checks if the return value looks like it fulfils the cursor
    /// protocol.  That means the result is a bulk item of length
    /// two with the first one being a cursor and the second a
    /// bulk response.
    pub fn looks_like_cursor(&self) -> bool {
        match *self {
            Value::Bulk(ref items) => {
                if items.len() != 2 {
                    return false;
                }
                match items[0] {
                    Value::Data(_) => {}
                    _ => {
                        return false;
                    }
                };
                match items[1] {
                    Value::Bulk(_) => {}
                    _ => {
                        return false;
                    }
                }
                return true;
            }
            _ => {
                return false;
            }
        }
    }
}

impl fmt::Debug for Value {
    fn fmt(&self, fmt: &mut fmt::Formatter) -> fmt::Result {
        match *self {
            Value::Nil => write!(fmt, "nil"),
            Value::Int(val) => write!(fmt, "int({:?})", val),
            Value::Data(ref val) => match from_utf8(val) {
                Ok(x) => write!(fmt, "string-data('{:?}')", x),
                Err(_) => write!(fmt, "binary-data({:?})", val),
            },
            Value::Bulk(ref values) => {
                try!(write!(fmt, "bulk("));
                let mut is_first = true;
                for val in values.iter() {
                    if !is_first {
                        try!(write!(fmt, ", "));
                    }
                    try!(write!(fmt, "{:?}", val));
                    is_first = false;
                }
                write!(fmt, ")")
            }
            Value::Okay => write!(fmt, "ok"),
            Value::Status(ref s) => write!(fmt, "status({:?})", s),
        }
    }
}

/// Represents a redis error.  For the most part you should be using
/// the Error trait to interact with this rather than the actual
/// struct.
pub struct RedisError {
    repr: ErrorRepr,
}

#[derive(Debug)]
enum ErrorRepr {
    WithDescription(ErrorKind, &'static str),
    WithDescriptionAndDetail(ErrorKind, &'static str, String),
    ExtensionError(String, String),
    IoError(io::Error),
}

impl PartialEq for RedisError {
    fn eq(&self, other: &RedisError) -> bool {
        match (&self.repr, &other.repr) {
            (&ErrorRepr::WithDescription(kind_a, _), &ErrorRepr::WithDescription(kind_b, _)) => {
                kind_a == kind_b
            }
            (
                &ErrorRepr::WithDescriptionAndDetail(kind_a, _, _),
                &ErrorRepr::WithDescriptionAndDetail(kind_b, _, _),
            ) => kind_a == kind_b,
            (&ErrorRepr::ExtensionError(ref a, _), &ErrorRepr::ExtensionError(ref b, _)) => {
                *a == *b
            }
            _ => false,
        }
    }
}

impl From<io::Error> for RedisError {
    fn from(err: io::Error) -> RedisError {
        RedisError {
            repr: ErrorRepr::IoError(err),
        }
    }
}

impl From<Utf8Error> for RedisError {
    fn from(_: Utf8Error) -> RedisError {
        RedisError {
            repr: ErrorRepr::WithDescription(ErrorKind::TypeError, "Invalid UTF-8"),
        }
    }
}

impl From<(ErrorKind, &'static str)> for RedisError {
    fn from((kind, desc): (ErrorKind, &'static str)) -> RedisError {
        RedisError {
            repr: ErrorRepr::WithDescription(kind, desc),
        }
    }
}

impl From<(ErrorKind, &'static str, String)> for RedisError {
    fn from((kind, desc, detail): (ErrorKind, &'static str, String)) -> RedisError {
        RedisError {
            repr: ErrorRepr::WithDescriptionAndDetail(kind, desc, detail),
        }
    }
}

impl error::Error for RedisError {
    fn description(&self) -> &str {
        match self.repr {
            ErrorRepr::WithDescription(_, desc) => desc,
            ErrorRepr::WithDescriptionAndDetail(_, desc, _) => desc,
            ErrorRepr::ExtensionError(_, _) => "extension error",
            ErrorRepr::IoError(ref err) => err.description(),
        }
    }

    fn cause(&self) -> Option<&error::Error> {
        match self.repr {
            ErrorRepr::IoError(ref err) => Some(err as &error::Error),
            _ => None,
        }
    }
}

impl fmt::Display for RedisError {
    fn fmt(&self, f: &mut fmt::Formatter) -> Result<(), fmt::Error> {
        match self.repr {
            ErrorRepr::WithDescription(_, desc) => desc.fmt(f),
            ErrorRepr::WithDescriptionAndDetail(_, desc, ref detail) => {
                try!(desc.fmt(f));
                try!(f.write_str(": "));
                detail.fmt(f)
            }
            ErrorRepr::ExtensionError(ref code, ref detail) => {
                try!(code.fmt(f));
                try!(f.write_str(": "));
                detail.fmt(f)
            }
            ErrorRepr::IoError(ref err) => err.fmt(f),
        }
    }
}

impl fmt::Debug for RedisError {
    fn fmt(&self, f: &mut fmt::Formatter) -> Result<(), fmt::Error> {
        fmt::Display::fmt(self, f)
    }
}

/// Indicates a general failure in the library.
impl RedisError {
    /// Returns the kind of the error.
    pub fn kind(&self) -> ErrorKind {
        match self.repr {
            ErrorRepr::WithDescription(kind, _) => kind,
            ErrorRepr::WithDescriptionAndDetail(kind, _, _) => kind,
            ErrorRepr::ExtensionError(_, _) => ErrorKind::ExtensionError,
            ErrorRepr::IoError(_) => ErrorKind::IoError,
        }
    }

    /// Returns the name of the error category for display purposes.
    pub fn category(&self) -> &str {
        match self.kind() {
            ErrorKind::ResponseError => "response error",
            ErrorKind::AuthenticationFailed => "authentication failed",
            ErrorKind::TypeError => "type error",
            ErrorKind::ExecAbortError => "script execution aborted",
            ErrorKind::BusyLoadingError => "busy loading",
            ErrorKind::NoScriptError => "no script",
            ErrorKind::InvalidClientConfig => "invalid client config",
            ErrorKind::IoError => "I/O error",
            ErrorKind::ExtensionError => "extension error",
        }
    }

    /// Indicates that this failure is an IO failure.
    pub fn is_io_error(&self) -> bool {
        match self.kind() {
            ErrorKind::IoError => true,
            _ => false,
        }
    }

    /// Returns true if this error indicates that the connection was
    /// refused.  You should generally not rely much on this function
    /// unless you are writing unit tests that want to detect if a
    /// local server is available.
    pub fn is_connection_refusal(&self) -> bool {
        match self.repr {
            ErrorRepr::IoError(ref err) => {
                match err.kind() {
                    io::ErrorKind::ConnectionRefused => true,
                    // if we connect to a unix socket and the file does not
                    // exist yet, then we want to treat this as if it was a
                    // connection refusal.
                    io::ErrorKind::NotFound => cfg!(any(
                        feature = "with-unix-sockets",
                        feature = "with-system-unix-sockets"
                    )),
                    _ => false,
                }
            }
            _ => false,
        }
    }

    /// Returns true if error was caused by I/O time out.
    /// Note that this may not be accurate depending on platform.
    pub fn is_timeout(&self) -> bool {
        match self.repr {
            ErrorRepr::IoError(ref err) => match err.kind() {
                io::ErrorKind::TimedOut => true,
                io::ErrorKind::WouldBlock => true,
                _ => false,
            },
            _ => false,
        }
    }

    /// Returns true if error was caused by a dropped connection.
    pub fn is_connection_dropped(&self) -> bool {
        match self.repr {
            ErrorRepr::IoError(ref err) => match err.kind() {
                io::ErrorKind::BrokenPipe | io::ErrorKind::ConnectionReset => true,
                _ => false,
            },
            _ => false,
        }
    }

    /// Returns the extension error code
    pub fn extension_error_code(&self) -> Option<&str> {
        match self.repr {
            ErrorRepr::ExtensionError(ref code, _) => Some(&code),
            _ => None,
        }
    }
}

pub fn make_extension_error(code: &str, detail: Option<&str>) -> RedisError {
    RedisError {
        repr: ErrorRepr::ExtensionError(
            code.to_string(),
            match detail {
                Some(x) => x.to_string(),
                None => "Unknown extension error encountered".to_string(),
            },
        ),
    }
}

/// Library generic result type.
pub type RedisResult<T> = Result<T, RedisError>;

pub type RedisFuture<T> = Box<Future<Item = T, Error = RedisError> + Send>;

/// An info dictionary type.
#[derive(Debug)]
pub struct InfoDict {
    map: HashMap<String, Value>,
}

/// This type provides convenient access to key/value data returned by
/// the "INFO" command.  It acts like a regular mapping but also has
/// a convenience method `get` which can return data in the appropriate
/// type.
///
/// For instance this can be used to query the server for the role it's
/// in (master, slave) etc:
///
/// ```rust,no_run
/// # fn do_something() -> redis::RedisResult<()> {
/// # let client = redis::Client::open("redis://127.0.0.1/").unwrap();
/// # let con = client.get_connection().unwrap();
/// let info : redis::InfoDict = try!(redis::cmd("INFO").query(&con));
/// let role : Option<String> = info.get("role");
/// # Ok(()) }
/// ```
impl InfoDict {
    /// Creates a new info dictionary from a string in the response of
    /// the INFO command.  Each line is a key, value pair with the
    /// key and value separated by a colon (`:`).  Lines starting with a
    /// hash (`#`) are ignored.
    pub fn new(kvpairs: &str) -> InfoDict {
        let mut map = HashMap::new();
        for line in kvpairs.lines() {
            if line.len() == 0 || line.starts_with("#") {
                continue;
            }
            let mut p = line.splitn(2, ':');
            let k = unwrap_or!(p.next(), continue).to_string();
            let v = unwrap_or!(p.next(), continue).to_string();
            map.insert(k, Value::Status(v));
        }
        InfoDict { map: map }
    }

    /// Fetches a value by key and converts it into the given type.
    /// Typical types are `String`, `bool` and integer types.
    pub fn get<T: FromRedisValue>(&self, key: &str) -> Option<T> {
        match self.find(&key) {
            Some(ref x) => from_redis_value(*x).ok(),
            None => None,
        }
    }

    pub fn find(&self, key: &&str) -> Option<&Value> {
        self.map.get(*key)
    }

    pub fn contains_key(&self, key: &&str) -> bool {
        self.find(key).is_some()
    }

    pub fn len(&self) -> usize {
        self.map.len()
    }
}

/// Used to convert a value into one or multiple redis argument
/// strings.  Most values will produce exactly one item but in
/// some cases it might make sense to produce more than one.
pub trait ToRedisArgs: Sized {
    /// This converts the value into a vector of bytes.  Each item
    /// is a single argument.  Most items generate a vector of a
    /// single item.
    ///
    /// The exception to this rule currently are vectors of items.
    fn to_redis_args(&self) -> Vec<Vec<u8>> {
        let mut out = Vec::new();
        self.write_redis_args(&mut out);
        out
    }

    /// This writes the value into a vector of bytes.  Each item
    /// is a single argument.  Most items generate a single item.
    ///
    /// The exception to this rule currently are vectors of items.
    fn write_redis_args(&self, out: &mut Vec<Vec<u8>>);

    /// Returns an information about the contained value with regards
    /// to it's numeric behavior in a redis context.  This is used in
    /// some high level concepts to switch between different implementations
    /// of redis functions (for instance `INCR` vs `INCRBYFLOAT`).
    fn describe_numeric_behavior(&self) -> NumericBehavior {
        NumericBehavior::NonNumeric
    }

    /// Returns an indiciation if the value contained is exactly one
    /// argument.  It returns false if it's zero or more than one.  This
    /// is used in some high level functions to intelligently switch
    /// between `GET` and `MGET` variants.
    fn is_single_arg(&self) -> bool {
        true
    }

    /// This only exists internally as a workaround for the lack of
    /// specialization.
    #[doc(hidden)]
    fn make_arg_vec(items: &[Self], out: &mut Vec<Vec<u8>>) {
        for item in items.iter() {
            item.write_redis_args(out);
        }
    }

    /// This only exists internally as a workaround for the lack of
    /// specialization.
    #[doc(hidden)]
    fn make_arg_iter_ref<'a, I>(items: I, out: &mut Vec<Vec<u8>>)
    where
        I: Iterator<Item = &'a Self>,
        Self: 'a,
    {
        for item in items {
            item.write_redis_args(out);
        }
    }

    #[doc(hidden)]
    fn is_single_vec_arg(items: &[Self]) -> bool {
        items.len() == 1 && items[0].is_single_arg()
    }
}

macro_rules! invalid_type_error {
    ($v:expr, $det:expr) => {{
        fail!((
            ErrorKind::TypeError,
            "Response was of incompatible type",
            format!("{:?} (response was {:?})", $det, $v)
        ));
    }};
}

macro_rules! string_based_to_redis_impl {
    ($t:ty, $numeric:expr) => {
        impl ToRedisArgs for $t {
            fn write_redis_args(&self, out: &mut Vec<Vec<u8>>) {
                let s = self.to_string();
                out.push(s.into_bytes())
            }

            fn describe_numeric_behavior(&self) -> NumericBehavior {
                $numeric
            }
        }
    };
}

impl ToRedisArgs for u8 {
    fn write_redis_args(&self, out: &mut Vec<Vec<u8>>) {
        let s = self.to_string();
        out.push(s.into_bytes());
    }

    fn make_arg_vec(items: &[u8], out: &mut Vec<Vec<u8>>) {
        out.push(items.to_vec());
    }

    fn is_single_vec_arg(_items: &[u8]) -> bool {
        true
    }
}

string_based_to_redis_impl!(i8, NumericBehavior::NumberIsInteger);
string_based_to_redis_impl!(i16, NumericBehavior::NumberIsInteger);
string_based_to_redis_impl!(u16, NumericBehavior::NumberIsInteger);
string_based_to_redis_impl!(i32, NumericBehavior::NumberIsInteger);
string_based_to_redis_impl!(u32, NumericBehavior::NumberIsInteger);
string_based_to_redis_impl!(i64, NumericBehavior::NumberIsInteger);
string_based_to_redis_impl!(u64, NumericBehavior::NumberIsInteger);
string_based_to_redis_impl!(f32, NumericBehavior::NumberIsFloat);
string_based_to_redis_impl!(f64, NumericBehavior::NumberIsFloat);
string_based_to_redis_impl!(isize, NumericBehavior::NumberIsInteger);
string_based_to_redis_impl!(usize, NumericBehavior::NumberIsInteger);
string_based_to_redis_impl!(bool, NumericBehavior::NonNumeric);

impl ToRedisArgs for String {
    fn write_redis_args(&self, out: &mut Vec<Vec<u8>>) {
        out.push(self.as_bytes().to_vec())
    }
}

impl<'a> ToRedisArgs for &'a String {
    fn write_redis_args(&self, out: &mut Vec<Vec<u8>>) {
        out.push(self.as_bytes().to_vec())
    }
}

impl<'a> ToRedisArgs for &'a str {
    fn write_redis_args(&self, out: &mut Vec<Vec<u8>>) {
        out.push(self.as_bytes().to_vec())
    }
}

impl<T: ToRedisArgs> ToRedisArgs for Vec<T> {
    fn write_redis_args(&self, out: &mut Vec<Vec<u8>>) {
        ToRedisArgs::make_arg_vec(self, out)
    }

    fn is_single_arg(&self) -> bool {
        ToRedisArgs::is_single_vec_arg(&self[..])
    }
}

impl<'a, T: ToRedisArgs> ToRedisArgs for &'a [T] {
    fn write_redis_args(&self, out: &mut Vec<Vec<u8>>) {
        ToRedisArgs::make_arg_vec(*self, out)
    }

    fn is_single_arg(&self) -> bool {
        ToRedisArgs::is_single_vec_arg(*self)
    }
}

impl<T: ToRedisArgs> ToRedisArgs for Option<T> {
    fn write_redis_args(&self, out: &mut Vec<Vec<u8>>) {
        match *self {
            Some(ref x) => x.write_redis_args(out),
            None => (),
        }
    }

    fn describe_numeric_behavior(&self) -> NumericBehavior {
        match *self {
            Some(ref x) => x.describe_numeric_behavior(),
            None => NumericBehavior::NonNumeric,
        }
    }

    fn is_single_arg(&self) -> bool {
        match *self {
            Some(ref x) => x.is_single_arg(),
            None => false,
        }
    }
}

/// @note: Redis cannot store empty sets so the application has to
/// check whether the set is empty and if so, not attempt to use that
/// result
impl<T: ToRedisArgs + Hash + Eq> ToRedisArgs for HashSet<T> {
    fn write_redis_args(&self, out: &mut Vec<Vec<u8>>) {
        ToRedisArgs::make_arg_iter_ref(self.iter(), out)
    }

    fn is_single_arg(&self) -> bool {
        self.len() <= 1
    }
}

/// @note: Redis cannot store empty sets so the application has to
/// check whether the set is empty and if so, not attempt to use that
/// result
impl<T: ToRedisArgs + Hash + Eq + Ord> ToRedisArgs for BTreeSet<T> {
    fn write_redis_args(&self, out: &mut Vec<Vec<u8>>) {
        ToRedisArgs::make_arg_iter_ref(self.iter(), out)
    }

    fn is_single_arg(&self) -> bool {
        self.len() <= 1
    }
}

/// this flattens BTreeMap into something that goes well with HMSET
/// @note: Redis cannot store empty sets so the application has to
/// check whether the set is empty and if so, not attempt to use that
/// result
impl<T: ToRedisArgs + Hash + Eq + Ord, V: ToRedisArgs> ToRedisArgs for BTreeMap<T, V> {
    fn write_redis_args(&self, out: &mut Vec<Vec<u8>>) {
        let mut rv = Vec::with_capacity(self.len() * 2);

        for (key, value) in self {
            // otherwise things like HMSET will simply NOT work
            assert!(key.is_single_arg() && value.is_single_arg());

            key.write_redis_args(&mut rv);
            value.write_redis_args(&mut rv);
        }

        ToRedisArgs::make_arg_vec(&rv, out)
    }

    fn is_single_arg(&self) -> bool {
        self.len() <= 1
    }
}

#[cfg(feature = "with-rustc-json")]
impl ToRedisArgs for json::Json {
    fn write_redis_args(&self, out: &mut Vec<Vec<u8>>) {
        // XXX: the encode result needs to be handled properly
        out.push(json::encode(self).unwrap().into_bytes())
    }
}

macro_rules! to_redis_args_for_tuple {
    () => ();
    ($($name:ident,)+) => (
        #[doc(hidden)]
        impl<$($name: ToRedisArgs),*> ToRedisArgs for ($($name,)*) {
            // we have local variables named T1 as dummies and those
            // variables are unused.
            #[allow(non_snake_case, unused_variables)]
            fn write_redis_args(&self, out: &mut Vec<Vec<u8>>) {
                let ($(ref $name,)*) = *self;
                $($name.write_redis_args(out);)*
            }

            #[allow(non_snake_case, unused_variables)]
            fn is_single_arg(&self) -> bool {
                let mut n = 0u32;
                $(let $name = (); n += 1;)*
                n == 1
            }
        }
        to_redis_args_for_tuple_peel!($($name,)*);
    )
}

/// This chips of the leading one and recurses for the rest.  So if the first
/// iteration was T1, T2, T3 it will recurse to T2, T3.  It stops for tuples
/// of size 1 (does not implement down to unit).
macro_rules! to_redis_args_for_tuple_peel {
    ($name:ident, $($other:ident,)*) => (to_redis_args_for_tuple!($($other,)*);)
}

to_redis_args_for_tuple! { T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, T11, T12, }

macro_rules! to_redis_args_for_array {
    ($($N:expr)+) => {
        $(
            impl<'a, T: ToRedisArgs> ToRedisArgs for &'a [T; $N] {
                fn write_redis_args(&self, out: &mut Vec<Vec<u8>>) {
                    ToRedisArgs::make_arg_vec(*self, out)
                }

                fn is_single_arg(&self) -> bool {
                    ToRedisArgs::is_single_vec_arg(*self)
                }
            }
        )+
    }
}

to_redis_args_for_array! {
     0  1  2  3  4  5  6  7  8  9
    10 11 12 13 14 15 16 17 18 19
    20 21 22 23 24 25 26 27 28 29
    30 31 32
}

/// This trait is used to convert a redis value into a more appropriate
/// type.  While a redis `Value` can represent any response that comes
/// back from the redis server, usually you want to map this into something
/// that works better in rust.  For instance you might want to convert the
/// return value into a `String` or an integer.
///
/// This trait is well supported throughout the library and you can
/// implement it for your own types if you want.
///
/// In addition to what you can see from the docs, this is also implemented
/// for tuples up to size 12 and for Vec<u8>.
pub trait FromRedisValue: Sized {
    /// Given a redis `Value` this attempts to convert it into the given
    /// destination type.  If that fails because it's not compatible an
    /// appropriate error is generated.
    fn from_redis_value(v: &Value) -> RedisResult<Self>;

    /// Similar to `from_redis_value` but constructs a vector of objects
    /// from another vector of values.  This primarily exists internally
    /// to customize the behavior for vectors of tuples.
    fn from_redis_values(items: &[Value]) -> RedisResult<Vec<Self>> {
        let mut rv = vec![];
        for item in items.iter() {
            match FromRedisValue::from_redis_value(item) {
                Ok(val) => rv.push(val),
                Err(_) => {}
            }
        }
        Ok(rv)
    }

    /// This only exists internally as a workaround for the lack of
    /// specialization.
    #[doc(hidden)]
    fn from_byte_vec(_vec: &[u8]) -> Option<Vec<Self>> {
        None
    }
}

macro_rules! from_redis_value_for_num_internal {
    ($t:ty, $v:expr) => {{
        let v = $v;
        match *v {
            Value::Int(val) => Ok(val as $t),
            Value::Status(ref s) => match s.parse::<$t>() {
                Ok(rv) => Ok(rv),
                Err(_) => invalid_type_error!(v, "Could not convert from string."),
            },
            Value::Data(ref bytes) => match try!(from_utf8(bytes)).parse::<$t>() {
                Ok(rv) => Ok(rv),
                Err(_) => invalid_type_error!(v, "Could not convert from string."),
            },
            _ => invalid_type_error!(v, "Response type not convertible to numeric."),
        }
    }};
}

macro_rules! from_redis_value_for_num {
    ($t:ty) => {
        impl FromRedisValue for $t {
            fn from_redis_value(v: &Value) -> RedisResult<$t> {
                from_redis_value_for_num_internal!($t, v)
            }
        }
    };
}

impl FromRedisValue for u8 {
    fn from_redis_value(v: &Value) -> RedisResult<u8> {
        from_redis_value_for_num_internal!(u8, v)
    }

    fn from_byte_vec(vec: &[u8]) -> Option<Vec<u8>> {
        Some(vec.to_vec())
    }
}

from_redis_value_for_num!(i8);
from_redis_value_for_num!(i16);
from_redis_value_for_num!(u16);
from_redis_value_for_num!(i32);
from_redis_value_for_num!(u32);
from_redis_value_for_num!(i64);
from_redis_value_for_num!(u64);
from_redis_value_for_num!(f32);
from_redis_value_for_num!(f64);
from_redis_value_for_num!(isize);
from_redis_value_for_num!(usize);

impl FromRedisValue for bool {
    fn from_redis_value(v: &Value) -> RedisResult<bool> {
        match *v {
            Value::Nil => Ok(false),
            Value::Int(val) => Ok(val != 0),
            Value::Status(ref s) => if &s[..] == "1" {
                Ok(true)
            } else if &s[..] == "0" {
                Ok(false)
            } else {
                invalid_type_error!(v, "Response status not valid boolean");
            },
            Value::Okay => Ok(true),
            _ => invalid_type_error!(v, "Response type not bool compatible."),
        }
    }
}

impl FromRedisValue for String {
    fn from_redis_value(v: &Value) -> RedisResult<String> {
        match *v {
            Value::Data(ref bytes) => Ok(try!(from_utf8(bytes)).to_string()),
            Value::Okay => Ok("OK".to_string()),
            Value::Status(ref val) => Ok(val.to_string()),
            _ => invalid_type_error!(v, "Response type not string compatible."),
        }
    }
}

impl<T: FromRedisValue> FromRedisValue for Vec<T> {
    fn from_redis_value(v: &Value) -> RedisResult<Vec<T>> {
        match *v {
            // this hack allows us to specialize Vec<u8> to work with
            // binary data whereas all others will fail with an error.
            Value::Data(ref bytes) => match FromRedisValue::from_byte_vec(bytes) {
                Some(x) => Ok(x),
                None => invalid_type_error!(v, "Response type not vector compatible."),
            },
            Value::Bulk(ref items) => FromRedisValue::from_redis_values(items),
            Value::Nil => Ok(vec![]),
            _ => invalid_type_error!(v, "Response type not vector compatible."),
        }
    }
}

impl<K: FromRedisValue + Eq + Hash, V: FromRedisValue> FromRedisValue for HashMap<K, V> {
    fn from_redis_value(v: &Value) -> RedisResult<HashMap<K, V>> {
        match *v {
            Value::Bulk(ref items) => {
                let mut rv = HashMap::new();
                let mut iter = items.iter();
                loop {
                    let k = unwrap_or!(iter.next(), break);
                    let v = unwrap_or!(iter.next(), break);
                    rv.insert(try!(from_redis_value(k)), try!(from_redis_value(v)));
                }
                Ok(rv)
            }
            _ => invalid_type_error!(v, "Response type not hashmap compatible"),
        }
    }
}

impl<K: FromRedisValue + Eq + Hash, V: FromRedisValue> FromRedisValue for BTreeMap<K, V>
where
    K: Ord,
{
    fn from_redis_value(v: &Value) -> RedisResult<BTreeMap<K, V>> {
        match *v {
            Value::Bulk(ref items) => {
                let mut rv = BTreeMap::new();
                let mut iter = items.iter();
                loop {
                    let k = unwrap_or!(iter.next(), break);
                    let v = unwrap_or!(iter.next(), break);
                    rv.insert(try!(from_redis_value(k)), try!(from_redis_value(v)));
                }
                Ok(rv)
            }
            _ => invalid_type_error!(v, "Response type not btreemap compatible"),
        }
    }
}

impl<T: FromRedisValue + Eq + Hash> FromRedisValue for HashSet<T> {
    fn from_redis_value(v: &Value) -> RedisResult<HashSet<T>> {
        match *v {
            Value::Bulk(ref items) => {
                let mut rv = HashSet::new();
                for item in items.iter() {
                    rv.insert(try!(from_redis_value(item)));
                }
                Ok(rv)
            }
            _ => invalid_type_error!(v, "Response type not hashset compatible"),
        }
    }
}

impl<T: FromRedisValue + Eq + Hash> FromRedisValue for BTreeSet<T>
where
    T: Ord,
{
    fn from_redis_value(v: &Value) -> RedisResult<BTreeSet<T>> {
        match *v {
            Value::Bulk(ref items) => {
                let mut rv = BTreeSet::new();
                for item in items.iter() {
                    rv.insert(try!(from_redis_value(item)));
                }
                Ok(rv)
            }
            _ => invalid_type_error!(v, "Response type not btreeset compatible"),
        }
    }
}

impl FromRedisValue for Value {
    fn from_redis_value(v: &Value) -> RedisResult<Value> {
        Ok(v.clone())
    }
}

impl FromRedisValue for () {
    fn from_redis_value(_v: &Value) -> RedisResult<()> {
        Ok(())
    }
}

macro_rules! from_redis_value_for_tuple {
    () => ();
    ($($name:ident,)+) => (
        #[doc(hidden)]
        impl<$($name: FromRedisValue),*> FromRedisValue for ($($name,)*) {
            // we have local variables named T1 as dummies and those
            // variables are unused.
            #[allow(non_snake_case, unused_variables)]
            fn from_redis_value(v: &Value) -> RedisResult<($($name,)*)> {
                match *v {
                    Value::Bulk(ref items) => {
                        // hacky way to count the tuple size
                        let mut n = 0;
                        $(let $name = (); n += 1;)*
                        if items.len() != n {
                            invalid_type_error!(v, "Bulk response of wrong dimension")
                        }

                        // this is pretty ugly too.  The { i += 1; i - 1} is rust's
                        // postfix increment :)
                        let mut i = 0;
                        Ok(($({let $name = (); try!(from_redis_value(
                             &items[{ i += 1; i - 1 }]))},)*))
                    }
                    _ => invalid_type_error!(v, "Not a bulk response")
                }
            }

            #[allow(non_snake_case, unused_variables)]
            fn from_redis_values(items: &[Value]) -> RedisResult<Vec<($($name,)*)>> {
                // hacky way to count the tuple size
                let mut n = 0;
                $(let $name = (); n += 1;)*
                if items.len() % n != 0 {
                    invalid_type_error!(items, "Bulk response of wrong dimension")
                }

                // this is pretty ugly too.  The { i += 1; i - 1} is rust's
                // postfix increment :)
                let mut rv = vec![];
                if items.len() == 0 {
                    return Ok(rv)
                }
                let mut offset = 0;
                while offset < items.len() - 1 {
                    rv.push(($({let $name = (); try!(from_redis_value(
                         &items[{ offset += 1; offset - 1 }]))},)*));
                }
                Ok(rv)
            }
        }
        from_redis_value_for_tuple_peel!($($name,)*);
    )
}

/// This chips of the leading one and recurses for the rest.  So if the first
/// iteration was T1, T2, T3 it will recurse to T2, T3.  It stops for tuples
/// of size 1 (does not implement down to unit).
macro_rules! from_redis_value_for_tuple_peel {
    ($name:ident, $($other:ident,)*) => (from_redis_value_for_tuple!($($other,)*);)
}

from_redis_value_for_tuple! { T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, T11, T12, }

impl FromRedisValue for InfoDict {
    fn from_redis_value(v: &Value) -> RedisResult<InfoDict> {
        let s: String = try!(from_redis_value(v));
        Ok(InfoDict::new(&s))
    }
}

#[cfg(feature = "with-rustc-json")]
impl FromRedisValue for json::Json {
    fn from_redis_value(v: &Value) -> RedisResult<json::Json> {
        let rv = match *v {
            Value::Data(ref b) => json::Json::from_str(try!(from_utf8(b))),
            Value::Status(ref s) => json::Json::from_str(s),
            _ => invalid_type_error!(v, "Not JSON compatible"),
        };
        match rv {
            Ok(value) => Ok(value),
            Err(_) => invalid_type_error!(v, "Not valid JSON"),
        }
    }
}

impl<T: FromRedisValue> FromRedisValue for Option<T> {
    fn from_redis_value(v: &Value) -> RedisResult<Option<T>> {
        match *v {
            Value::Nil => {
                return Ok(None);
            }
            _ => {}
        }
        Ok(Some(try!(from_redis_value(v))))
    }
}

/// A shortcut function to invoke `FromRedisValue::from_redis_value`
/// to make the API slightly nicer.
pub fn from_redis_value<T: FromRedisValue>(v: &Value) -> RedisResult<T> {
    FromRedisValue::from_redis_value(v)
}