Fix input reader

Signed-off-by: trivernis <trivernis@protonmail.com>

Cargo.toml

@@ -17,8 +17,8 @@ log = "0.4.14"
 
 [dependencies.tokio]
 version = "1.5.0"
-features = ["io-util", "io-std"]
+features = ["io-util", "io-std", "fs"]
 
 [dev-dependencies.tokio]
 version = "1.5.0"
-features = ["rt-multi-thread", "test-util"]
+features = ["rt-multi-thread", "macros"]

src/error.rs

@@ -6,4 +6,7 @@ pub type TapeResult<T> = Result<T, TapeError>;
 pub enum TapeError {
     #[error("IO Error: {0}")]
     TokioIoError(#[from] tokio::io::Error),
+
+    #[error("Unexpected EOF")]
+    EOF,
 }

src/input.rs

@@ -1,50 +0,0 @@
-use crate::error::TapeResult;
-use crate::traits::AsyncReadSeek;
-use std::io::SeekFrom;
-use tokio::io::{AsyncReadExt, BufReader};
-use tokio::io::{AsyncSeekExt, ErrorKind};
-
-/// An Input reader to asynchronously read a type
-/// that implements AsyncBufRead and AsyncSeek.
-pub struct InputReader {
-    inner: BufReader<Box<dyn AsyncReadSeek>>,
-}
-
-impl InputReader {
-    pub fn new<T: AsyncReadSeek + 'static>(inner: T) -> Self {
-        Self {
-            inner: BufReader::new(Box::new(inner)),
-        }
-    }
-
-    /// Reads the next char consuming it in the process
-    pub async fn consume(&mut self) -> TapeResult<char> {
-        self.read_next().await
-    }
-
-    /// Returns the next char without forwarding
-    pub async fn peek(&mut self) -> TapeResult<char> {
-        let char = self.read_next().await?;
-        self.inner.get_mut().seek(SeekFrom::Current(-1)).await?;
-
-        Ok(char)
-    }
-
-    /// Returns if EOF has been reached
-    pub async fn check_eof(&mut self) -> TapeResult<bool> {
-        let char = self.read_next().await?;
-
-        Ok(char == '\x00')
-    }
-
-    /// Reads the next char returning \x00 for EOF
-    async fn read_next(&mut self) -> TapeResult<char> {
-        let mut value = String::with_capacity(1);
-
-        match self.inner.read_to_string(&mut value).await {
-            Ok(_) => Ok(value.chars().next().unwrap()),
-            Err(e) if e.kind() == ErrorKind::UnexpectedEof => Ok('\x00'),
-            Err(e) => Err(e.into()),
-        }
-    }
-}

src/input_reader.rs

@@ -0,0 +1,81 @@
+use crate::error::{TapeError, TapeResult};
+use std::io::ErrorKind;
+use tokio::io::{AsyncBufRead, AsyncBufReadExt};
+
+/// An Input reader to asynchronously read a type
+/// that implements AsyncBufRead and AsyncSeek.
+pub struct InputReader {
+    inner: Box<dyn AsyncBufRead + Unpin>,
+    buf: String,
+    index: usize,
+}
+
+impl InputReader {
+    pub fn new<T: AsyncBufRead + Unpin + 'static>(inner: T) -> Self {
+        Self {
+            inner: Box::new(inner),
+            buf: String::new(),
+            index: 0,
+        }
+    }
+
+    /// Reads the next char consuming it in the process
+    #[inline]
+    pub async fn consume(&mut self) -> TapeResult<char> {
+        self.read_next().await
+    }
+
+    /// Returns the next char without forwarding
+    #[inline]
+    pub async fn peek(&mut self) -> TapeResult<char> {
+        let char = self.read_next().await?;
+        self.seek_to(self.index - 1).await?;
+
+        Ok(char)
+    }
+
+    /// Returns if EOF has been reached
+    #[inline]
+    pub async fn check_eof(&mut self) -> bool {
+        if let Err(TapeError::EOF) = self.read_next().await {
+            true
+        } else {
+            false
+        }
+    }
+
+    /// Reads the next char returning \x00 for EOF
+    async fn read_next(&mut self) -> TapeResult<char> {
+        self.seek_to(self.index + 1).await?;
+        let result = self
+            .buf
+            .get(self.index - 1..self.index)
+            .ok_or(TapeError::EOF)?
+            .chars()
+            .next()
+            .ok_or(TapeError::EOF);
+
+        result
+    }
+
+    /// Seeks to a given index
+    pub async fn seek_to(&mut self, to_index: usize) -> TapeResult<()> {
+        while to_index >= self.buf.len() {
+            let mut line = String::new();
+            self.inner.read_line(&mut line).await.map_err(|e| {
+                if e.kind() == ErrorKind::UnexpectedEof {
+                    TapeError::EOF
+                } else {
+                    TapeError::TokioIoError(e)
+                }
+            })?;
+            if line.is_empty() {
+                break;
+            }
+            self.buf.push_str(&line);
+        }
+        self.index = to_index;
+
+        Ok(())
+    }
+}

src/lib.rs

@@ -1,3 +1,5 @@
 pub mod error;
-pub mod input;
-mod traits;
+pub mod input_reader;
+
+#[cfg(test)]
+mod tests;

src/tests/mod.rs

@@ -0,0 +1 @@
+mod test_input;

src/tests/test_input.rs

@@ -0,0 +1,41 @@
+use crate::error::{TapeError, TapeResult};
+use crate::input_reader::InputReader;
+use std::io::Cursor;
+
+fn get_reader() -> InputReader {
+    let data = "ABCDEFG HIJKLMNOP 12345567890\nSecond Line\n\n";
+    InputReader::new(Cursor::new(data))
+}
+
+#[tokio::test]
+async fn it_peeks() {
+    let mut reader = get_reader();
+    assert_eq!(reader.peek().await.unwrap(), 'A');
+    assert_eq!(reader.peek().await.unwrap(), 'A');
+    assert_eq!(reader.peek().await.unwrap(), 'A');
+}
+
+#[tokio::test]
+async fn it_consumes() {
+    let mut reader = get_reader();
+    assert_eq!(reader.consume().await.unwrap(), 'A');
+    assert_eq!(reader.consume().await.unwrap(), 'B');
+    assert_eq!(reader.consume().await.unwrap(), 'C');
+}
+
+#[tokio::test]
+async fn it_checks_for_eof() {
+    let mut reader = get_reader();
+    assert!(!is_eof(reader.seek_to(29).await));
+    assert!(!reader.check_eof().await);
+    assert!(!is_eof(reader.seek_to(47).await));
+    assert!(is_eof(reader.consume().await.map(|_| ())));
+    assert!(reader.check_eof().await);
+}
+
+fn is_eof(result: TapeResult<()>) -> bool {
+    match result {
+        Err(TapeError::EOF) => true,
+        _ => false,
+    }
+}

src/traits.rs

@@ -1,3 +0,0 @@
-use tokio::io::{AsyncRead, AsyncSeek};
-
-pub trait AsyncReadSeek: AsyncRead + AsyncSeek + Unpin {}