Add CSV support

Fixes #2

Cargo.toml

@@ -8,3 +8,7 @@ edition = "2021"
 [dependencies]
 serde = { version = "1", features = ["derive"] }
 serde_json = "1"
+csv = { version = "1", optional = true }
+
+[features]
+csv = ["dep:csv"]

src/backend.rs

@@ -1,2 +1,5 @@
 pub mod json;
 pub mod jsonlines;
+
+#[cfg(feature = "csv")]
+pub mod csv;

src/backend/csv.rs

@@ -0,0 +1,87 @@
+use std::io::{Read, Write};
+
+use serde::{de::DeserializeOwned, Serialize};
+
+use crate::common::Result;
+
+pub fn read<T: DeserializeOwned>(reader: impl Read) -> Result<Vec<T>> {
+    let mut rdr = csv::Reader::from_reader(reader);
+    let mut records: Vec<T> = Vec::new();
+    for result in rdr.deserialize() {
+        let record: T = result?;
+        records.push(record);
+    }
+    Ok(records)
+}
+
+pub fn write<T: Serialize>(writer: impl Write, records: &[T]) -> Result<()> {
+    let mut wtr = csv::Writer::from_writer(writer);
+    for record in records {
+        wtr.serialize(record)?;
+    }
+    wtr.flush()?;
+    Ok(())
+}
+
+#[cfg(test)]
+mod test {
+    use std::io::Cursor;
+
+    use serde::{Deserialize, Serialize};
+
+    use super::{read, write};
+
+    #[derive(Debug, Deserialize, Serialize, PartialEq, Eq)]
+    struct Record {
+        id: u32,
+        name: String,
+    }
+
+    #[test]
+    fn test_read() {
+        let text = r#"
+id,name
+1,foo
+2,bar"#;
+
+        let records: Vec<Record> = read(Cursor::new(text)).unwrap();
+        let expected = vec![
+            Record {
+                id: 1,
+                name: "foo".to_owned(),
+            },
+            Record {
+                id: 2,
+                name: "bar".to_owned(),
+            },
+        ];
+        assert_eq!(expected, records);
+    }
+
+    #[test]
+    fn test_write() {
+        let records = vec![
+            Record {
+                id: 1,
+                name: "foo".to_owned(),
+            },
+            Record {
+                id: 2,
+                name: "bar".to_owned(),
+            },
+        ];
+        let mut cursor = Cursor::new(vec![]);
+        write(&mut cursor, &records).unwrap();
+        let data = String::from_utf8(cursor.into_inner())
+            .unwrap()
+            .trim()
+            .to_string();
+        let expected = r#"
+id,name
+1,foo
+2,bar"#
+            .trim()
+            .to_owned();
+        assert_eq!(expected, data);
+    }
+}

src/common.rs

@@ -4,6 +4,10 @@ use std::{fmt::Display, path::Path};
 pub enum FileFormat {
     Json,
     JsonLines,
+    #[cfg(feature = "csv")]
+    Csv,
+    #[cfg(feature = "yaml")]
+    Yaml,
 }
 
 impl TryFrom<&str> for FileFormat {
@@ -13,6 +17,10 @@ impl TryFrom<&str> for FileFormat {
         match value.trim().to_lowercase().as_str() {
             "json" => Ok(FileFormat::Json),
             "jsonl" | "jsl" => Ok(FileFormat::JsonLines),
+            #[cfg(feature = "yaml")]
+            "csv" => Ok(FileFormat::Csv),
+            #[cfg(feature = "yaml")]
+            "yaml" | "yml" => Ok(FileFormat::Yaml),
             _ => Err(format!("Unknown file format: {}", value)),
         }
     }
@@ -35,6 +43,10 @@ impl Display for FileFormat {
         match self {
             FileFormat::Json => write!(f, "json"),
             FileFormat::JsonLines => write!(f, "jsonl"),
+            #[cfg(feature = "csv")]
+            FileFormat::Csv => write!(f, "csv"),
+            #[cfg(feature = "yaml")]
+            FileFormat::Yaml => write!(f, "yaml"),
         }
     }
 }

src/read.rs

@@ -24,6 +24,8 @@ pub fn read_records_from_reader<T: DeserializeOwned>(
     match file_format {
         FileFormat::Json => backend::json::read(reader),
         FileFormat::JsonLines => backend::jsonlines::read(reader),
+        #[cfg(feature = "csv")]
+        FileFormat::Csv => backend::csv::read(reader),
     }
 }
 

src/write.rs

@@ -35,6 +35,8 @@ pub fn write_records_to_writer<T: Serialize>(
     match file_format {
         FileFormat::Json => backend::json::write(writer, records),
         FileFormat::JsonLines => backend::jsonlines::write(writer, records),
+        #[cfg(feature = "csv")]
+        FileFormat::Csv => backend::csv::write(writer, records),
     }
 }