Inspired by Python's csv
module, a very basic csv reader & writer.
The primary use-case of this library is interacting with unstructured, variably structured, or dubiously structured data. As such, you probably want the far more robust and far better implemented csv
crate.
Goals:
- Provide a
String
-based mechanism to read and write CSV files inrfc4180
format. - Handle mixed formats resiliently, such as mismatched and newlines within quotes.
Non-Goals:
- Any interpretation of the contents of the CSV structure itself - everything is an owned
String
serde
support - if you need it, go use thecsv
crate.
- Straight Iteration:
use irox_csv::error::CSVError;
fn iter_example() -> Result<(), CSVError> {
let mut input = irox_csv::CSVReader::new(std::io::stdin());
loop {
// iterate over each line of the input
let line : Option<Vec<String>> = input.read_line()?;
match line {
Some(fields) => {
// Use the individual fields of the CSV line
println!("{:?}", fields); // fields : Vec<String>
}
None => {
// EOF
break;
}
}
}
Ok(())
}
- Map Iteration:
use irox_csv::error::CSVError;
fn map_example() -> Result<(), CSVError> {
let mut maps = irox_csv::CSVMapReader::new(std::io::stdin());
loop {
// iterate over each line of the input
let maybe_row : Option<Row> = maps.next_row()?;
match maybe_row {
Some(row) => {
// Use the individual fields of the CSV line as a key-value map
// The keys are the column headers found in the first row, the values are the matching row entry
let map = row.into_map_lossy();
println!("{:?}", map); // map : BTree<column:String, rowVal:String>
}
None => {
// EOF
break;
}
}
}
Ok(())
}
- Writing a CSV File using Maps:
fn map_writer_example() -> Result<(), CSVError> {
let mut buf: Vec<u8> = Vec::new();
let mut writer = CSVWriterBuilder::new()
.with_columns(&["first", "second", "third"])
.build(&mut buf);
let mut map = BTreeMap::new();
map.insert("first".to_string(), "firstColFirstRowVal".to_string());
map.insert("second".to_string(), "secondColFirstRowVal".to_string());
map.insert("third".to_string(), "thirdColFirstRowVal".to_string());
writer.write_fields(&map)?;
map.clear();
map.insert("first".to_string(), "firstColSecondRowVal".to_string());
map.insert("second".to_string(), "secondColSecondRowVal".to_string());
map.insert("third".to_string(), "thirdColSecondRowVal".to_string());
writer.write_fields(&map)?;
Ok(())
}
will result in a buffer:
first,second,third
firstColFirstRowVal,secondColFirstRowVal,thirdColFirstRowVal
firstColSecondRowVal,secondColSecondRowVal,thirdColSecondRowVal