London | 26-SDC-Mar | Mariia Serhiienko | Sprint 3 | Implement shell tools

implement-shell-tools/cat/cat.js

@@ -0,0 +1,56 @@
+import { promises as fs } from "node:fs";
+import process from "node:process";
+
+const args = process.argv.slice(2);
+
+if (args.length === 0) {
+  console.error("Usage: node cat.js [-n] [-b] <file...>");
+  process.exit(1);
+}
+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 -- '${unknownFlags[0].slice(1)}'`);
+  process.exit(1);
+}
+
+const filePaths = args.filter((arg) => !arg.startsWith("-"));
+
+let lineNumber = 1;
+
+for (const filePath of filePaths) {
+  const content = await fs.readFile(filePath, "utf-8");
+
+  if (!showAllLineNumbers && !showNonBlankNumbers) {
+    process.stdout.write(content);
+  } else {
+    const lines = content.split("\n");
+
+    for (let i = 0; i < lines.length; i++) {
+      const line = lines[i];
+
+      const isLastLine = i === lines.length - 1;
+
+      if (isLastLine && line === "") {
+        break;
+      }
+
+      const isBlankLine = line.trim() === "";
+      const needsLineNumber =
+        showAllLineNumbers || (showNonBlankNumbers && !isBlankLine);
+
+      if (needsLineNumber) {
+        const paddedNumber = String(lineNumber).padStart(6, " ");
+        process.stdout.write(`${paddedNumber}\t${line}\n`);
+        lineNumber++;
+      } else if (showNonBlankNumbers && isBlankLine) {
+        process.stdout.write("\n");
+      }
+    }
+  }
+}

implement-shell-tools/ls/ls.js

@@ -0,0 +1,59 @@
+import { promises as fs } from "node:fs";
+import process from "node:process";
+
+const args = process.argv.slice(2);
+
+const showHidden = args.includes("-a");
+
+const supportedFlags = ["-1", "-a"];
+const unknownFlags = args.filter(
+  (arg) => arg.startsWith("-") && !supportedFlags.includes(arg),
+);
+
+if (unknownFlags.length > 0) {
+  console.error(`ls: invalid option -- '${unknownFlags[0].slice(1)}'`);
+  process.exit(1);
+}
+
+const paths = args.filter((arg) => !arg.startsWith("-"));
+
+const targetPaths = paths.length > 0 ? paths : [process.cwd()];
+
+for (const targetPath of targetPaths) {
+  if (targetPaths.length > 1) {
+    process.stdout.write(`${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");
+  }
+}

implement-shell-tools/package.json

@@ -0,0 +1,3 @@
+{
+  "type": "module"
+}

implement-shell-tools/wc/wc.js

@@ -0,0 +1,85 @@
+import { promises as fs } from "node:fs";
+import process from "node:process";
+
+const args = process.argv.slice(2);
+
+const expandedArgs = [];
+for (const arg of args) {
+  if (arg.startsWith("-") && arg.length > 2) {
+    for (const char of arg.slice(1)) {
+      expandedArgs.push(`-${char}`);
+    }
+  } else {
+    expandedArgs.push(arg);
+  }
+}
+
+const showLines = expandedArgs.includes("-l");
+const showWords = expandedArgs.includes("-w");
+const showBytes = expandedArgs.includes("-c");
+
+const supportedFlags = ["-l", "-w", "-c"];
+const unknownFlags = expandedArgs.filter(
+  (arg) => arg.startsWith("-") && !supportedFlags.includes(arg),
+);
+
+if (unknownFlags.length > 0) {
+  console.error(`wc: invalid option -- '${unknownFlags[0].slice(1)}'`);
+  process.exit(1);
+}
+
+const noSpecificFlag = !showLines && !showWords && !showBytes;
+
+const filePaths = expandedArgs.filter((arg) => !arg.startsWith("-"));
+
+if (filePaths.length === 0) {
+  console.error("Usage: node wc.js [-l] [-w] [-c] <file...>");
+  process.exit(1);
+}
+
+const results = [];
+
+for (const filePath of filePaths) {
+  const content = await fs.readFile(filePath, "utf-8");
+
+  const lines = content.endsWith("\n")
+    ? content.split("\n").length - 1
+    : content.split("\n").length;
+
+  const words = content.split(/\s+/).filter((w) => w.length > 0).length;
+
+  const bytes = Buffer.byteLength(content, "utf-8");
+
+  results.push({ filePath, lines, words, bytes });
+}
+
+const totalLines = results.reduce((sum, r) => sum + r.lines, 0);
+const totalWords = results.reduce((sum, r) => sum + r.words, 0);
+const totalBytes = results.reduce((sum, r) => sum + r.bytes, 0);
+
+function getCounts(lines, words, bytes) {
+  const counts = [];
+  if (noSpecificFlag || showLines) counts.push(lines);
+  if (noSpecificFlag || showWords) counts.push(words);
+  if (noSpecificFlag || showBytes) counts.push(bytes);
+  return counts;
+}
+
+const maxNumber = Math.max(...getCounts(totalLines, totalWords, totalBytes));
+
+const width = String(maxNumber).length + 1;
+
+function formatLine(counts, label) {
+  const parts = counts.map((n) => String(n).padStart(width, " "));
+  return parts.join("") + " " + label;
+}
+
+for (const { filePath, lines, words, bytes } of results) {
+  const counts = getCounts(lines, words, bytes);
+  process.stdout.write(formatLine(counts, filePath) + "\n");
+}
+
+if (results.length > 1) {
+  const totals = getCounts(totalLines, totalWords, totalBytes);
+  process.stdout.write(formatLine(totals, "total") + "\n");
+}