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use csv_core::WriterBuilder as CoreWriterBuilder;
use crate::{QuoteStyle, Terminator};
/// Builds a CSV writer with various configuration knobs.
///
/// This builder can be used to tweak the field delimiter, record terminator
/// and more. Once a CSV `AsyncWriter` is built, its configuration cannot be
/// changed.
#[derive(Debug)]
pub struct AsyncWriterBuilder {
builder: CoreWriterBuilder,
capacity: usize,
flexible: bool,
}
impl Default for AsyncWriterBuilder {
fn default() -> AsyncWriterBuilder {
AsyncWriterBuilder {
builder: CoreWriterBuilder::default(),
capacity: 8 * (1 << 10),
flexible: false,
}
}
}
impl AsyncWriterBuilder {
/// Create a new builder for configuring CSV writing.
///
/// To convert a builder into a writer, call one of the methods starting
/// with `from_`.
///
/// # Example
///
/// ```
/// use std::error::Error;
/// use csv_async::AsyncWriterBuilder;
///
/// # fn main() { async_std::task::block_on(async {example().await.unwrap()}); }
/// async fn example() -> Result<(), Box<dyn Error>> {
/// let mut wtr = AsyncWriterBuilder::new().from_writer(vec![]);
/// wtr.write_record(&["a", "b", "c"]).await?;
/// wtr.write_record(&["x", "y", "z"]).await?;
///
/// let data = String::from_utf8(wtr.into_inner().await?)?;
/// assert_eq!(data, "a,b,c\nx,y,z\n");
/// Ok(())
/// }
/// ```
pub fn new() -> AsyncWriterBuilder {
AsyncWriterBuilder::default()
}
/// Returns csv_core Builder reference.
pub fn get_core_builder_ref(&self) -> &CoreWriterBuilder {
&self.builder
}
/// The field delimiter to use when writing CSV.
///
/// The default is `b','`.
///
/// # Example
///
/// ```
/// use std::error::Error;
/// use csv_async::AsyncWriterBuilder;
///
/// # fn main() { async_std::task::block_on(async {example().await.unwrap()}); }
/// async fn example() -> Result<(), Box<dyn Error>> {
/// let mut wtr = AsyncWriterBuilder::new()
/// .delimiter(b';')
/// .from_writer(vec![]);
/// wtr.write_record(&["a", "b", "c"]).await?;
/// wtr.write_record(&["x", "y", "z"]).await?;
///
/// let data = String::from_utf8(wtr.into_inner().await?)?;
/// assert_eq!(data, "a;b;c\nx;y;z\n");
/// Ok(())
/// }
/// ```
pub fn delimiter(&mut self, delimiter: u8) -> &mut AsyncWriterBuilder {
self.builder.delimiter(delimiter);
self
}
/// Returns information if read file has headers.
pub fn is_flexible(&self) -> bool {
self.flexible
}
/// Whether the number of fields in records is allowed to change or not.
///
/// When disabled (which is the default), writing CSV data will return an
/// error if a record is written with a number of fields different from the
/// number of fields written in a previous record.
///
/// When enabled, this error checking is turned off.
///
/// # Example: writing flexible records
///
/// ```
/// use std::error::Error;
/// use csv_async::AsyncWriterBuilder;
///
/// # fn main() { async_std::task::block_on(async {example().await.unwrap()}); }
/// async fn example() -> Result<(), Box<dyn Error>> {
/// let mut wtr = AsyncWriterBuilder::new()
/// .flexible(true)
/// .from_writer(vec![]);
/// wtr.write_record(&["a", "b"]).await?;
/// wtr.write_record(&["x", "y", "z"]).await?;
///
/// let data = String::from_utf8(wtr.into_inner().await?)?;
/// assert_eq!(data, "a,b\nx,y,z\n");
/// Ok(())
/// }
/// ```
///
/// # Example: error when `flexible` is disabled
///
/// ```
/// use std::error::Error;
/// use csv_async::AsyncWriterBuilder;
///
/// # fn main() { async_std::task::block_on(async {example().await.unwrap()}); }
/// async fn example() -> Result<(), Box<dyn Error>> {
/// let mut wtr = AsyncWriterBuilder::new()
/// .flexible(false)
/// .from_writer(vec![]);
/// wtr.write_record(&["a", "b"]).await?;
/// let err = wtr.write_record(&["x", "y", "z"]).await.unwrap_err();
/// match *err.kind() {
/// csv_async::ErrorKind::UnequalLengths { expected_len, len, .. } => {
/// assert_eq!(expected_len, 2);
/// assert_eq!(len, 3);
/// }
/// ref wrong => {
/// panic!("expected UnequalLengths but got {:?}", wrong);
/// }
/// }
/// Ok(())
/// }
/// ```
pub fn flexible(&mut self, yes: bool) -> &mut AsyncWriterBuilder {
self.flexible = yes;
self
}
/// The record terminator to use when writing CSV.
///
/// A record terminator can be any single byte. The default is `\n`.
///
/// Note that RFC 4180 specifies that record terminators should be `\r\n`.
/// To use `\r\n`, use the special `Terminator::CRLF` value.
///
/// # Example: CRLF
///
/// This shows how to use RFC 4180 compliant record terminators.
///
/// ```
/// use std::error::Error;
/// use csv_async::{Terminator, AsyncWriterBuilder};
///
/// # fn main() { async_std::task::block_on(async {example().await.unwrap()}); }
/// async fn example() -> Result<(), Box<dyn Error>> {
/// let mut wtr = AsyncWriterBuilder::new()
/// .terminator(Terminator::CRLF)
/// .from_writer(vec![]);
/// wtr.write_record(&["a", "b", "c"]).await?;
/// wtr.write_record(&["x", "y", "z"]).await?;
///
/// let data = String::from_utf8(wtr.into_inner().await?)?;
/// assert_eq!(data, "a,b,c\r\nx,y,z\r\n");
/// Ok(())
/// }
/// ```
pub fn terminator(&mut self, term: Terminator) -> &mut AsyncWriterBuilder {
self.builder.terminator(term.to_core());
self
}
/// The quoting style to use when writing CSV.
///
/// By default, this is set to `QuoteStyle::Necessary`, which will only
/// use quotes when they are necessary to preserve the integrity of data.
///
/// Note that unless the quote style is set to `Never`, an empty field is
/// quoted if it is the only field in a record.
///
/// # Example: non-numeric quoting
///
/// This shows how to quote non-numeric fields only.
///
/// ```
/// use std::error::Error;
/// use csv_async::{QuoteStyle, AsyncWriterBuilder};
///
/// # fn main() { async_std::task::block_on(async {example().await.unwrap()}); }
/// async fn example() -> Result<(), Box<dyn Error>> {
/// let mut wtr = AsyncWriterBuilder::new()
/// .quote_style(QuoteStyle::NonNumeric)
/// .from_writer(vec![]);
/// wtr.write_record(&["a", "5", "c"]).await?;
/// wtr.write_record(&["3.14", "y", "z"]).await?;
///
/// let data = String::from_utf8(wtr.into_inner().await?)?;
/// assert_eq!(data, "\"a\",5,\"c\"\n3.14,\"y\",\"z\"\n");
/// Ok(())
/// }
/// ```
///
/// # Example: never quote
///
/// This shows how the CSV writer can be made to never write quotes, even
/// if it sacrifices the integrity of the data.
///
/// ```
/// use std::error::Error;
/// use csv_async::{QuoteStyle, AsyncWriterBuilder};
///
/// # fn main() { async_std::task::block_on(async {example().await.unwrap()}); }
/// async fn example() -> Result<(), Box<dyn Error>> {
/// let mut wtr = AsyncWriterBuilder::new()
/// .quote_style(QuoteStyle::Never)
/// .from_writer(vec![]);
/// wtr.write_record(&["a", "foo\nbar", "c"]).await?;
/// wtr.write_record(&["g\"h\"i", "y", "z"]).await?;
///
/// let data = String::from_utf8(wtr.into_inner().await?)?;
/// assert_eq!(data, "a,foo\nbar,c\ng\"h\"i,y,z\n");
/// Ok(())
/// }
/// ```
pub fn quote_style(&mut self, style: QuoteStyle) -> &mut AsyncWriterBuilder {
self.builder.quote_style(style.to_core());
self
}
/// The quote character to use when writing CSV.
///
/// The default is `b'"'`.
///
/// # Example
///
/// ```
/// use std::error::Error;
/// use csv_async::AsyncWriterBuilder;
///
/// # fn main() { async_std::task::block_on(async {example().await.unwrap()}); }
/// async fn example() -> Result<(), Box<dyn Error>> {
/// let mut wtr = AsyncWriterBuilder::new()
/// .quote(b'\'')
/// .from_writer(vec![]);
/// wtr.write_record(&["a", "foo\nbar", "c"]).await?;
/// wtr.write_record(&["g'h'i", "y\"y\"y", "z"]).await?;
///
/// let data = String::from_utf8(wtr.into_inner().await?)?;
/// assert_eq!(data, "a,'foo\nbar',c\n'g''h''i',y\"y\"y,z\n");
/// Ok(())
/// }
/// ```
pub fn quote(&mut self, quote: u8) -> &mut AsyncWriterBuilder {
self.builder.quote(quote);
self
}
/// Enable double quote escapes.
///
/// This is enabled by default, but it may be disabled. When disabled,
/// quotes in field data are escaped instead of doubled.
///
/// # Example
///
/// ```
/// use std::error::Error;
/// use csv_async::AsyncWriterBuilder;
///
/// # fn main() { async_std::task::block_on(async {example().await.unwrap()}); }
/// async fn example() -> Result<(), Box<dyn Error>> {
/// let mut wtr = AsyncWriterBuilder::new()
/// .double_quote(false)
/// .from_writer(vec![]);
/// wtr.write_record(&["a", "foo\"bar", "c"]).await?;
/// wtr.write_record(&["x", "y", "z"]).await?;
///
/// let data = String::from_utf8(wtr.into_inner().await?)?;
/// assert_eq!(data, "a,\"foo\\\"bar\",c\nx,y,z\n");
/// Ok(())
/// }
/// ```
pub fn double_quote(&mut self, yes: bool) -> &mut AsyncWriterBuilder {
self.builder.double_quote(yes);
self
}
/// The escape character to use when writing CSV.
///
/// In some variants of CSV, quotes are escaped using a special escape
/// character like `\` (instead of escaping quotes by doubling them).
///
/// By default, writing these idiosyncratic escapes is disabled, and is
/// only used when `double_quote` is disabled.
///
/// # Example
///
/// ```
/// use std::error::Error;
/// use csv_async::AsyncWriterBuilder;
///
/// # fn main() { async_std::task::block_on(async {example().await.unwrap()}); }
/// async fn example() -> Result<(), Box<dyn Error>> {
/// let mut wtr = AsyncWriterBuilder::new()
/// .double_quote(false)
/// .escape(b'$')
/// .from_writer(vec![]);
/// wtr.write_record(&["a", "foo\"bar", "c"]).await?;
/// wtr.write_record(&["x", "y", "z"]).await?;
///
/// let data = String::from_utf8(wtr.into_inner().await?)?;
/// assert_eq!(data, "a,\"foo$\"bar\",c\nx,y,z\n");
/// Ok(())
/// }
/// ```
pub fn escape(&mut self, escape: u8) -> &mut AsyncWriterBuilder {
self.builder.escape(escape);
self
}
/// Returns buffer capacity.
pub fn get_buffer_capacity(&self) -> usize {
self.capacity
}
/// Set the capacity (in bytes) of the internal buffer used in the CSV
/// writer. This defaults to a reasonable setting.
pub fn buffer_capacity(&mut self, capacity: usize) -> &mut AsyncWriterBuilder {
self.capacity = capacity;
self
}
}