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//! This crate provides a streaming CSV (comma separated values) writer and //! reader that works with the `serialize` crate to do type based encoding //! and decoding. There are two primary goals of this project: //! //! 1. The default mode of parsing should *just work*. This means the parser //! will bias toward providing *a* parse over a *correct* parse (with //! respect to RFC 4180). //! 2. Convenient to use by default, but when performance is needed, the //! API will provide an escape hatch. //! //! ## Simple example //! //! This shows how you can decode records into Rust types. This saves a ton //! of boiler plate, e.g., converting strings to numeric types. //! //! ```rust //! let data = " //! sticker,mortals,7 //! bribed,personae,7 //! wobbling,poncing,4 //! interposed,emmett,9 //! chocolate,refile,7"; //! //! let mut rdr = csv::Reader::from_string(data).has_headers(false); //! for row in rdr.decode() { //! let (n1, n2, dist): (String, String, u32) = row.unwrap(); //! println!("{}, {}: {}", n1, n2, dist); //! } //! ``` //! //! If you just want a `Vec` of all the records, then you can use the //! `collect` method defined on iterators: //! //! ```rust //! let data = " //! sticker,mortals,7 //! bribed,personae,7 //! wobbling,poncing,4 //! interposed,emmett,9 //! chocolate,refile,7"; //! //! type Row = (String, String, u32); //! //! let mut rdr = csv::Reader::from_string(data).has_headers(false); //! let rows = rdr.decode().collect::<csv::Result<Vec<Row>>>().unwrap(); //! assert_eq!(rows.len(), 5); //! ``` //! //! Please see the `Reader` type for more documentation and examples. //! //! ## Iteratoring over records //! //! This crate exposes **4** distinct ways of iterating over CSV records. In //! the majority of use cases, you should use the `decode` method as shown //! above because it is the most convenient. But other types of iterators are //! exposed for when you need them. //! //! The iterators listed below are presented in order of performance. The first //! (type based decoding) is the slowest and the last (zero allocation) is the //! fastest. There is clear evidence of this claim in the benchmarks. (Just //! run `cargo bench`.) //! //! ### Decoded records //! //! As shown above. This uses type based decoding on each record. //! //! ### String records //! //! Yields each record as a `Vec<String>`. Namely, this assumes that all CSV //! data is UTF-8 encoded. This is the standard CSV interface that you've //! probably come to expect from using other CSV parsers. //! //! ```rust //! let data = " //! sticker,mortals,7 //! bribed,personae,7 //! wobbling,poncing,4 //! interposed,emmett,9 //! chocolate,refile,7"; //! //! let mut rdr = csv::Reader::from_string(data).has_headers(false); //! for row in rdr.records().map(|r| r.unwrap()) { //! println!("{:?}", row); //! } //! ``` //! //! ### Byte string records //! //! Yields each record as a `Vec<ByteString>`. Namely, this allows reading CSV //! data that is not UTF-8 encoded (or improperly encoded!). //! //! ```rust //! let data = b" //! sti\xffcker,mortals,7 //! chocolate,refile,7"; //! //! let mut rdr = csv::Reader::from_bytes(&data[..]).has_headers(false); //! for row in rdr.byte_records().map(|r| r.unwrap()) { //! println!("{:?}", row); //! } //! ``` //! //! ### Byte slice records //! //! This iterator is defined on the `Reader` type itself and yields *fields* //! instead of records (unlike the other iterators). Each field is a `&[u8]`. //! No allocation is performed during parsing (unlike the other iterators, //! which at least allocate a `Vec<u8>` for each field and a `Vec<_>` for each //! record). Since no allocation is performed, this "iterator" doesn't actually //! implement the `Iterator` trait (since it cannot be done safely). //! //! This is the lowest level interface and should only be used when you need //! the performance. //! //! ```rust //! let data = " //! sticker,mortals,7 //! bribed,personae,7 //! wobbling,poncing,4 //! interposed,emmett,9 //! chocolate,refile,7"; //! //! let mut rdr = csv::Reader::from_string(data); //! while !rdr.done() { //! while let Some(r) = rdr.next_bytes().into_iter_result() { //! print!("{:?} ", r.unwrap()); //! } //! println!(""); //! } //! ``` //! //! There is more explanation for how this iterator interface works on the //! `Reader` type. //! //! ## Indexing //! //! This crate has experimental support for CSV record indexing. It's very //! simplistic, but once the index is created, you can seek a `csv::Reader` //! to any record instantly. See the //! [`csv::index`](/rustdoc/csv/index/index.html) //! sub-module for more details and examples. //! //! ## Compliance with RFC 4180 //! //! [RFC 4180](http://tools.ietf.org/html/rfc4180) seems to the closest thing //! to an official specification for CSV. Currently, the parser in this crate //! will read a strict superset of RFC 4180 while the writer will always write //! CSV data that conforms to RFC 4180 (unless configured to do otherwise). //! This approach was taken because CSV data is commonly malformed and there is //! nothing worse than trying to read busted CSV data with a library that says //! it can't do it. //! //! With that said, a "strict" mode may be added that will only read CSV data //! that conforms to RFC 4180. //! //! Here are a few notes on compatibility with RFC 4180: //! //! * Both CRLF and LF line endings are supported. This is seamless in the //! parser. By default, the encoder uses LF line endings but can be //! instructed to use CRLF with the `crlf` method. //! * The first record is read as a "header" by default, but this can be //! disabled by calling `has_headers(false)` before reading any records. //! (N.B. The encoder has no explicit support for headers. Simply encode a //! vector of strings instead.) //! * By default, the delimiter is a comma, but it can be changed to any //! **ASCII** byte character with the `delimiter` method (for either //! writing or reading). //! * By default, both the writer and reader will enforce the invariant //! that all records are the same length. (This is what RFC 4180 demands.) //! If a record with a different length is found, an error is returned. //! This behavior may be turned off by calling `flexible` with `true`. //! * Empty lines (that do not include other whitespace) are ignored //! by the parser. //! * This crates parses CSV data at the *byte* level, which means all //! delimiter and quote characters must be ASCII. While unfortunate, this //! means that CSV data that is not UTF-8 encoded can be parsed. In //! general, the writer and reader API biases toward using Unicode strings //! while providing an outlet to use byte strings. #![crate_name = "csv"] #![doc(html_root_url = "http://burntsushi.net/rustdoc/csv")] #![deny(missing_docs)] extern crate byteorder; extern crate rustc_serialize; use std::error::Error as StdError; use std::fmt; use std::io; use std::result; pub use borrow_bytes::BorrowBytes; pub use encoder::Encoded; pub use decoder::Decoded; pub use reader::{ Reader, DecodedRecords, StringRecords, ByteRecords, NextField, RecordTerminator, }; pub use writer::{Writer, QuoteStyle}; macro_rules! lg { ($($tt:tt)*) => ({ use std::io::Write; writeln!(&mut ::std::io::stderr(), $($tt)*).unwrap(); }); } pub mod index; mod borrow_bytes; mod encoder; mod decoder; mod reader; mod writer; #[cfg(test)] mod tests; /// A convenience type for representing the result of most CSV reader/writer /// operations. pub type Result<T> = result::Result<T, Error>; /// A convenience type for referring to a plain byte string. pub type ByteString = Vec<u8>; /// An error produced by an operation on CSV data. #[derive(Debug)] pub enum Error { /// An error reported by the type-based encoder. Encode(String), /// An error reported by the type-based decoder. Decode(String), /// An error reported by the CSV parser. Parse(LocatableError<ParseError>), /// An error originating from reading or writing to the underlying buffer. Io(io::Error), /// An error originating from using a CSV index. Index(String), } /// An error tagged with a location at which it occurred. #[derive(Clone, Copy, Debug)] pub struct LocatableError<T> { /// The record number (starting at 1). pub record: u64, /// The field number (starting at 1). pub field: u64, /// The error. pub err: T, } /// A description of a CSV parse error. #[derive(Clone, Copy, Debug)] pub enum ParseError { /// A record was found that has a different size than other records. /// /// This is only reported when `flexible` is set to `false` on the /// corresponding CSV reader/writer. UnequalLengths { /// Expected a record with this many fields. expected: u64, /// Got a record with this many fields. got: u64, }, /// An error occurred when trying to convert a field to a Unicode string. /// /// TODO: Include the real Utf8Error, but it is not stabilized yet. InvalidUtf8, } impl fmt::Display for Error { fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result { match *self { Error::Encode(ref msg) => write!(f, "CSV encode error: {}", msg), Error::Decode(ref msg) => write!(f, "CSV decode error: {}", msg), Error::Parse(ref err) => write!(f, "{}", err), Error::Io(ref err) => write!(f, "{}", err), Error::Index(ref msg) => write!(f, "CSV index error: {}", msg), } } } impl<T: fmt::Display> fmt::Display for LocatableError<T> { fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result { write!(f, "CSV error (at record {}, field {}): {}", self.record, self.field, self.err) } } impl fmt::Display for ParseError { fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result { match *self { ParseError::UnequalLengths { expected, got } => write!(f, "First record has length {}, but found record \ with length {}.", expected, got), ParseError::InvalidUtf8 => write!(f, "Invalid UTF8 encoding."), } } } impl StdError for Error { fn description(&self) -> &str { match *self { Error::Encode(..) => "CSV encoding error", Error::Decode(..) => "CSV decoding error", Error::Parse(..) => "CSV parse error", Error::Io(..) => "CSV IO error", Error::Index(..) => "CSV indexing error", } } fn cause(&self) -> Option<&StdError> { match *self { Error::Io(ref err) => Some(err), _ => None, } } } impl From<io::Error> for Error { fn from(err: io::Error) -> Error { Error::Io(err) } }