Add get_ref() and get_mut() methods

Author: jwodder

CHANGELOG.md

@@ -0,0 +1,8 @@
+v0.2.0 (in development)
+-----------------------
+- Gave `JsonLinesReader` and `JsonLinesWriter` new `get_ref()` and `get_mut()`
+  methods
+
+v0.1.0 (2022-10-28)
+-------------------
+Initial release

Cargo.toml

@@ -1,6 +1,6 @@
 [package]
 name = "serde-jsonlines"
-version = "0.1.0"
+version = "0.2.0-dev"
 edition = "2021"
 rust-version = "1.56"
 description = "Read & write JSON Lines documents"

README.md

@@ -3,7 +3,7 @@
 [![codecov.io](https://codecov.io/gh/jwodder/serde-jsonlines/branch/master/graph/badge.svg)](https://codecov.io/gh/jwodder/serde-jsonlines)
 [![MIT License](https://img.shields.io/github/license/jwodder/serde-jsonlines.svg)](https://opensource.org/licenses/MIT)
 
-[GitHub](https://github.com/jwodder/serde-jsonlines) | [crates.io](https://crates.io/crates/serde-jsonlines) | [Documentation](https://docs.rs/serde-jsonlines) | [Issues](https://github.com/jwodder/serde-jsonlines/issues)
+[GitHub](https://github.com/jwodder/serde-jsonlines) | [crates.io](https://crates.io/crates/serde-jsonlines) | [Documentation](https://docs.rs/serde-jsonlines) | [Issues](https://github.com/jwodder/serde-jsonlines/issues) | [Changelog](https://github.com/jwodder/serde-jsonlines/blob/master/CHANGELOG.md)
 
 JSON Lines (a.k.a. newline-delimited JSON) is a simple format for storing
 sequences of JSON values in which each value is serialized on a single line and

src/lib.rs

@@ -139,6 +139,16 @@ impl<W> JsonLinesWriter<W> {
     pub fn into_inner(self) -> W {
         self.inner
     }
+
+    /// Get a reference to the underlying writer
+    pub fn get_ref(&self) -> &W {
+        &self.inner
+    }
+
+    /// Get a mutable reference to the underlying writer
+    pub fn get_mut(&mut self) -> &mut W {
+        &mut self.inner
+    }
 }
 
 impl<W: Write> JsonLinesWriter<W> {
@@ -267,6 +277,16 @@ impl<R> JsonLinesReader<R> {
     pub fn into_inner(self) -> R {
         self.inner
     }
+
+    /// Get a reference to the underlying reader
+    pub fn get_ref(&self) -> &R {
+        &self.inner
+    }
+
+    /// Get a mutable reference to the underlying reader
+    pub fn get_mut(&mut self) -> &mut R {
+        &mut self.inner
+    }
 }
 
 impl<R: BufRead> JsonLinesReader<R> {

tests/json_lines_reader.rs

@@ -1,8 +1,8 @@
-use assert_fs::fixture::FileTouch;
+use assert_fs::fixture::{FileTouch, FileWriteStr};
 use assert_fs::NamedTempFile;
 use serde_jsonlines::JsonLinesReader;
-use std::fs::File;
-use std::io::{BufRead, BufReader, ErrorKind, Result};
+use std::fs::{File, OpenOptions};
+use std::io::{BufRead, BufReader, ErrorKind, Result, Seek, SeekFrom, Write};
 use std::path::Path;
 mod common;
 use common::*;
@@ -187,3 +187,43 @@ fn test_iter_invalid_json() {
     );
     assert!(items.next().is_none());
 }
+
+#[test]
+fn test_read_then_write_then_read() {
+    let tmpfile = NamedTempFile::new("test.jsonl").unwrap();
+    tmpfile
+        .write_str("{\"name\": \"Foo Bar\", \"on\":true,\"size\": 42 }\n")
+        .unwrap();
+    let fp = BufReader::new(
+        OpenOptions::new()
+            .read(true)
+            .write(true)
+            .open(&tmpfile)
+            .unwrap(),
+    );
+    let mut reader = JsonLinesReader::new(fp);
+    assert_eq!(
+        reader.read::<Structure>().unwrap(),
+        Some(Structure {
+            name: "Foo Bar".into(),
+            size: 42,
+            on: true,
+        })
+    );
+    assert_eq!(reader.read::<Structure>().unwrap(), None);
+    let fp: &mut File = reader.get_mut().get_mut();
+    let pos = fp.stream_position().unwrap();
+    fp.write_all(b"{ \"name\":\"Quux\", \"on\" : false ,\"size\": 23}\n")
+        .unwrap();
+    fp.flush().unwrap();
+    fp.seek(SeekFrom::Start(pos)).unwrap();
+    assert_eq!(
+        reader.read::<Structure>().unwrap(),
+        Some(Structure {
+            name: "Quux".into(),
+            size: 23,
+            on: false,
+        })
+    );
+    assert_eq!(reader.read::<Structure>().unwrap(), None);
+}

tests/json_lines_writer.rs

@@ -2,7 +2,7 @@ use assert_fs::assert::PathAssert;
 use assert_fs::NamedTempFile;
 use serde_jsonlines::JsonLinesWriter;
 use std::fs::File;
-use std::io::Write;
+use std::io::{Seek, SeekFrom, Write};
 use std::iter::empty;
 mod common;
 use common::*;
@@ -109,3 +109,31 @@ fn test_write_all_none() {
     }
     tmpfile.assert("");
 }
+
+#[test]
+fn test_write_then_back_up_then_write() {
+    let tmpfile = NamedTempFile::new("test.jsonl").unwrap();
+    {
+        let fp = File::create(&tmpfile).unwrap();
+        let mut writer = JsonLinesWriter::new(fp);
+        writer
+            .write(&Structure {
+                name: "Foo Bar".into(),
+                size: 42,
+                on: true,
+            })
+            .unwrap();
+        writer.flush().unwrap();
+        let fp: &mut File = writer.get_mut();
+        fp.seek(SeekFrom::Start(0)).unwrap();
+        writer
+            .write(&Structure {
+                name: "Gnusto Cleesh".into(),
+                size: 17,
+                on: true,
+            })
+            .unwrap();
+        writer.flush().unwrap();
+    }
+    tmpfile.assert("{\"name\":\"Gnusto Cleesh\",\"size\":17,\"on\":true}\n");
+}