Userland: Add wc program (#228)

Fixes #159.

Userland/wc.cpp

@@ -0,0 +1,128 @@
+#include <AK/AKString.h>
+#include <AK/Vector.h>
+#include <LibCore/CArgsParser.h>
+
+#include <ctype.h>
+#include <stdio.h>
+
+bool output_chars = false;
+bool output_words = false;
+bool output_lines = false;
+
+struct Count {
+    String file;
+    unsigned long chars = 0;
+    unsigned long words = 0;
+    unsigned long lines = 0;
+};
+
+void report(const Count& count)
+{
+    if (output_lines) {
+        printf("%lu ", count.lines);
+    }
+    if (output_words) {
+        printf("%lu ", count.words);
+    }
+    if (output_chars) {
+        printf("%lu ", count.chars);
+    }
+    printf("%s\n", count.file.characters());
+}
+
+void report(const Vector<Count>& counts)
+{
+    Count total { "total" };
+    for (const auto& c : counts) {
+        report(c);
+        total.lines += c.lines;
+        total.words += c.words;
+        total.chars += c.chars;
+    }
+    if (counts.size() > 1) {
+        report(total);
+    }
+    fflush(stdout);
+}
+
+int count_words(const char* s)
+{
+    int n = 0;
+    bool in_word = false;
+    for (; *s; ++s) {
+        if (!isspace(*s)) {
+            if (!in_word) {
+                in_word = true;
+                ++n;
+            }
+        } else if (in_word) {
+            in_word = false;
+        }
+    }
+    return n;
+}
+
+int main(int argc, char** argv)
+{
+    if (argc < 2) {
+        printf("usage: wc [-c|-m] [-lw] [file...]");
+        return 0;
+    }
+
+    CArgsParser args_parser("wc");
+    args_parser.add_arg("l", "Include lines in count");
+    args_parser.add_arg("c", "Include bytes in count");
+    args_parser.add_arg("m", "Include chars in count");
+    args_parser.add_arg("w", "Include words in count");
+    CArgsParserResult args = args_parser.parse(argc, (const char**)argv);
+
+    if (args.is_present("l")) {
+        output_lines = true;
+    }
+    if (args.is_present("c")) {
+        output_chars = true;
+    }
+    if (args.is_present("m")) {
+        output_chars = true;
+    }
+    if (args.is_present("w")) {
+        output_words = true;
+    }
+    if (!output_lines && !output_words && !output_chars) {
+        output_lines = output_chars = output_words = true;
+    }
+
+    Vector<String> files = args.get_single_values();
+    if (files.is_empty()) {
+        fprintf(stderr, "wc: No files provided");
+        return 1;
+    }
+
+    Vector<Count> counts;
+    for (const auto& f : files) {
+        FILE* fp = fopen(f.characters(), "r");
+        if (fp == nullptr) {
+            fprintf(stderr, "wc: Could not open file '%s'\n", f.characters());
+            return 1;
+        }
+
+        Count count { f };
+        char* line = nullptr;
+        size_t len = 0;
+        ssize_t n_read = 0;
+        while ((n_read = getline(&line, &len, fp)) != -1) {
+            count.lines++;
+            count.words += count_words(line);
+            count.chars += n_read;
+        }
+
+        counts.append(count);
+        fclose(fp);
+        if (line) {
+            free(line);
+        }
+    }
+
+    report(counts);
+    return 0;
+}