expand: move logic to expand a single line into its own function

src/uu/expand/src/expand.rs

@@ -366,21 +366,14 @@ enum CharType {
     Other,
 }
 
-#[allow(clippy::cognitive_complexity)]
+fn expand_line(
-fn expand(options: &Options) -> UResult<()> {
+    buf: &mut Vec<u8>,
+    output: &mut BufWriter<std::io::Stdout>,
+    ts: &[usize],
+    options: &Options,
+) -> std::io::Result<()> {
     use self::CharType::*;
 
-    let mut output = BufWriter::new(stdout());
-    let ts = options.tabstops.as_ref();
-    let mut buf = Vec::new();
-
-    for file in &options.files {
-        let mut fh = open(file)?;
-
-        while match fh.read_until(b'\n', &mut buf) {
-            Ok(s) => s > 0,
-            Err(_) => buf.is_empty(),
-        } {
     let mut col = 0;
     let mut byte = 0;
     let mut init = true;
@@ -428,18 +421,12 @@ fn expand(options: &Options) -> UResult<()> {
                 // now dump out either spaces if we're expanding, or a literal tab if we're not
                 if init || !options.iflag {
                     if nts <= options.tspaces.len() {
-                                output
+                        output.write_all(options.tspaces[..nts].as_bytes())?;
-                                    .write_all(options.tspaces[..nts].as_bytes())
-                                    .map_err_context(|| "failed to write output".to_string())?;
                     } else {
-                                output
+                        output.write_all(" ".repeat(nts).as_bytes())?;
-                                    .write_all(" ".repeat(nts).as_bytes())
-                                    .map_err_context(|| "failed to write output".to_string())?;
                     };
                 } else {
-                            output
+                    output.write_all(&buf[byte..byte + nbytes])?;
-                                .write_all(&buf[byte..byte + nbytes])
-                                .map_err_context(|| "failed to write output".to_string())?;
                 }
             }
             _ => {
@@ -457,19 +444,33 @@ fn expand(options: &Options) -> UResult<()> {
                     init = false;
                 }
 
-                        output
+                output.write_all(&buf[byte..byte + nbytes])?;
-                            .write_all(&buf[byte..byte + nbytes])
-                            .map_err_context(|| "failed to write output".to_string())?;
             }
         }
 
         byte += nbytes; // advance the pointer
     }
 
-            output
+    output.flush()?;
-                .flush()
-                .map_err_context(|| "failed to write output".to_string())?;
     buf.truncate(0); // clear the buffer
+
+    Ok(())
+}
+
+fn expand(options: &Options) -> UResult<()> {
+    let mut output = BufWriter::new(stdout());
+    let ts = options.tabstops.as_ref();
+    let mut buf = Vec::new();
+
+    for file in &options.files {
+        let mut fh = open(file)?;
+
+        while match fh.read_until(b'\n', &mut buf) {
+            Ok(s) => s > 0,
+            Err(_) => buf.is_empty(),
+        } {
+            expand_line(&mut buf, &mut output, ts, options)
+                .map_err_context(|| "failed to write output".to_string())?;
         }
     }
     Ok(())