task: complete implementation of wc in javascript

Author: XiaoQuark

implement-shell-tools/wc/wc.mjs

@@ -0,0 +1,142 @@
+import process from "node:process";
+import fs from "node:fs";
+import { parseArgs } from "node:util";
+
+const options = {
+	lines: {
+		type: "boolean",
+		short: "l",
+	},
+	words: {
+		type: "boolean",
+		short: "w",
+	},
+	bytes: {
+		type: "boolean",
+		short: "c",
+	},
+};
+
+const { values, positionals } = parseArgs({
+	options,
+	allowPositionals: true,
+});
+
+if (positionals.length === 0) {
+	process.stderr.write("Please provide a file.\n");
+	process.exit(1);
+}
+
+const results = [];
+
+// read file and calculate counts
+for (const path of positionals) {
+	const content = fs.readFileSync(path, "utf-8");
+
+	const lineCount = [...content].filter((char) => char === "\n").length;
+
+	const trimmedContent = content.trim();
+
+	const wordCount =
+		trimmedContent === "" ? 0 : trimmedContent.split(/\s+/).length;
+
+	const byteCount = Buffer.byteLength(content);
+
+	results.push({
+		path,
+		lineCount,
+		wordCount,
+		byteCount,
+	});
+}
+
+let totalLines = 0;
+let totalWords = 0;
+let totalBytes = 0;
+
+// calculate total counts
+for (const result of results) {
+	totalLines += result.lineCount;
+	totalWords += result.wordCount;
+	totalBytes += result.byteCount;
+}
+
+const allCounts = [];
+
+for (const result of results) {
+	const counts = getSelectedCounts(
+		result.lineCount,
+		result.wordCount,
+		result.byteCount,
+	);
+
+	allCounts.push(...counts);
+}
+
+if (results.length > 1) {
+	const totalCounts = getSelectedCounts(totalLines, totalWords, totalBytes);
+
+	allCounts.push(...totalCounts);
+}
+
+// flags handling function
+function getSelectedCounts(lineCount, wordCount, byteCount) {
+	const counts = [];
+
+	if (values.lines) {
+		counts.push(lineCount);
+	}
+
+	if (values.words) {
+		counts.push(wordCount);
+	}
+
+	if (values.bytes) {
+		counts.push(byteCount);
+	}
+
+	if (counts.length === 0) {
+		counts.push(lineCount, wordCount, byteCount);
+	}
+
+	return counts;
+}
+
+// output formatting
+let largestByteCount = 0;
+
+for (const result of results) {
+	if (result.byteCount > largestByteCount) {
+		largestByteCount = result.byteCount;
+	}
+}
+
+if (results.length > 1 && totalBytes > largestByteCount) {
+	largestByteCount = totalBytes;
+}
+
+const width = String(largestByteCount).length;
+
+for (const result of results) {
+	const counts = getSelectedCounts(
+		result.lineCount,
+		result.wordCount,
+		result.byteCount,
+	);
+
+	const formattedCounts = counts
+		.map((count) => String(count).padStart(width))
+		.join(" ");
+
+	process.stdout.write(`${formattedCounts} ${result.path}\n`);
+}
+
+if (results.length > 1) {
+	const totalCounts = getSelectedCounts(totalLines, totalWords, totalBytes);
+
+	const formattedTotals = totalCounts
+		.map((count) => String(count).padStart(width))
+		.join(" ");
+
+	process.stdout.write(`${formattedTotals} total\n`);
+}