address PR feedback: unknown flags check, simplify cat logic, support multiple directories in ls

Author: Konvaly

implement-shell-tools/cat/cat.js

@@ -9,6 +9,15 @@ if (args.length === 0) {
 }
 const showAllLineNumbers = args.includes("-n");
 const showNonBlankNumbers = args.includes("-b");
+const supportedFlags = ["-n", "-b"];
+const unknownFlags = args.filter(
+  (arg) => arg.startsWith("-") && !supportedFlags.includes(arg),
+);
+
+if (unknownFlags.length > 0) {
+  console.error(`cat: invalid option -- '${unknownFlags[0].slice(1)}'`);
+  process.exit(1);
+}
 
 const filePaths = args.filter((arg) => !arg.startsWith("-"));
 
@@ -25,29 +34,22 @@ for (const filePath of filePaths) {
     for (let i = 0; i < lines.length; i++) {
       const line = lines[i];
 
-      let isLastLine;
-      if (i === lines.length - 1) {
-        isLastLine = true;
-      } else {
-        isLastLine = false;
-      }
+      const isLastLine = i === lines.length - 1;
 
       if (isLastLine && line === "") {
         break;
       }
 
-      if (showAllLineNumbers) {
+      const isBlankLine = line.trim() === "";
+      const needsLineNumber =
+        showAllLineNumbers || (showNonBlankNumbers && !isBlankLine);
+
+      if (needsLineNumber) {
         const paddedNumber = String(lineNumber).padStart(6, " ");
         process.stdout.write(`${paddedNumber}\t${line}\n`);
         lineNumber++;
-      } else if (showNonBlankNumbers) {
-        if (line.trim() === "") {
-          process.stdout.write("\n");
-        } else {
-          const paddedNumber = String(lineNumber).padStart(6, " ");
-          process.stdout.write(`${paddedNumber}\t${line}\n`);
-          lineNumber++;
-        }
+      } else if (showNonBlankNumbers && isBlankLine) {
+        process.stdout.write("\n");
       }
     }
   }

implement-shell-tools/ls/ls.js

@@ -5,26 +5,55 @@ const args = process.argv.slice(2);
 
 const showHidden = args.includes("-a");
 
-const paths = args.filter((arg) => !arg.startsWith("-"));
-
-const targetPath = paths.length > 0 ? paths[0] : process.cwd();
-
-let entries = await fs.readdir(targetPath);
-
-if (!showHidden) {
-  entries = entries.filter((entry) => !entry.startsWith("."));
+const supportedFlags = ["-1", "-a"];
+const unknownFlags = args.filter(
+  (arg) => arg.startsWith("-") && !supportedFlags.includes(arg),
+);
+
+if (unknownFlags.length > 0) {
+  console.error(`ls: invalid option -- '${unknownFlags[0].slice(1)}'`);
+  process.exit(1);
 }
 
-if (showHidden) {
-  entries = [".", "..", ...entries];
-}
-
-entries.sort((a, b) => {
-  const cleanA = a.replace(/^\.+/, "");
-  const cleanB = b.replace(/^\.+/, "");
-  return cleanA.localeCompare(cleanB);
-});
+const paths = args.filter((arg) => !arg.startsWith("-"));
 
-for (const entry of entries) {
-  process.stdout.write(entry + "\n");
+const targetPaths = paths.length > 0 ? paths : [process.cwd()];
+
+for (const targetPath of targetPaths) {
+  if (targetPaths.length > 1) {
+    process.stdout.write(`${targetPath}:\n`);
+  }
+
+  let entries;
+
+  try {
+    entries = await fs.readdir(targetPath);
+  } catch (error) {
+    console.error(
+      `ls: cannot access '${targetPath}': No such file or directory`,
+    );
+    continue;
+  }
+
+  if (!showHidden) {
+    entries = entries.filter((entry) => !entry.startsWith("."));
+  }
+
+  if (showHidden) {
+    entries = [".", "..", ...entries];
+  }
+
+  entries.sort((a, b) => {
+    const cleanA = a.replace(/^\.+/, "");
+    const cleanB = b.replace(/^\.+/, "");
+    return cleanA.localeCompare(cleanB);
+  });
+
+  for (const entry of entries) {
+    process.stdout.write(entry + "\n");
+  }
+
+  if (targetPaths.length > 1) {
+    process.stdout.write("\n");
+  }
 }