add: multiple fixes, docs for deployment

src/rewriter.rs

@@ -58,23 +58,34 @@ impl Rewriter {
                 // Open 2 files; one to read and translate, and one to write.
                 let source_file = File::open(&src_path)?;
                 let mut dest_file = File::create(&dst_path)?;
-                let reader = BufReader::new(source_file);
+                let mut buff = Vec::with_capacity(2048);
+                let mut reader = BufReader::new(source_file);
 
-                for line in reader.lines() {
-                    let line = line?;
+                while let Ok(count) = reader.read_until(b'\n', &mut buff) {
+                    if count == 0 {
+                        break;
+                    }
                     // If the line is not subject to replacement, copy it and
                     // carry on.
-                    if !line.contains(&self.source) {
-                        writeln!(dest_file, "{}", line)?;
+                    let line = &buff[0..count];
+                    let m = contains(&self.source.as_bytes(), line);
+                    if m.is_none() {
+                        dest_file.write(&line)?;
+                        buff.clear();
                         continue;
                     }
+                    let m = m.unwrap();
+                    let start = &line[0..m.0];
+                    let end = &line[m.1..];
 
                     // Else, repeat the line multiple times, replacing the string
                     // in question
                     for replacement in &replacements {
-                        let new_line = line.replace(&self.source, &replacement);
-                        writeln!(dest_file, "{}", new_line)?;
+                        dest_file.write(start)?;
+                        dest_file.write(replacement.as_bytes())?;
+                        dest_file.write(end)?;
                     }
+                    buff.clear();
                 }
             }
         }
@@ -82,6 +93,21 @@ impl Rewriter {
     }
 }
 
+fn contains(needle: &[u8], haystack: &[u8]) -> Option<(usize, usize)> {
+    let mut i = 0;
+    while i + needle.len() <= haystack.len() {
+        let mut j = 0;
+        while i+j < haystack.len() && j < needle.len() && haystack[i+j] == needle[j] {
+            j += 1;
+        }
+        if j == needle.len() {
+            return Some((i, i+j));
+        }
+        i += 1;
+    }
+    None
+}
+
 #[cfg(test)]
 mod tests {
     use include_directory::{Dir, include_directory};