ArgumentParser+date: Add value arguments

apps/CMakeLists.txt

@@ -9,7 +9,9 @@ endfunction()
 luna_app(init.cpp init)
 luna_app(cat.cpp cat)
 luna_app(sh.cpp sh)
+
 luna_app(date.cpp date)
+target_link_libraries(date PRIVATE os)
 
 luna_app(edit.cpp edit)
 target_link_libraries(edit PRIVATE os)

apps/date.cpp

@@ -1,10 +1,21 @@
+#include <os/ArgumentParser.h>
+
 #include <stddef.h>
 #include <stdio.h>
+#include <stdlib.h>
 #include <time.h>
 
-int main()
+int main(int argc, char** argv)
 {
-    time_t now = time(NULL);
+    StringView date;
+
+    ArgumentParser parser;
+    parser.add_value_argument(date, 'd', "date", false);
+    parser.parse(argc, argv);
+
+    time_t now;
+    if (date.is_empty()) { now = time(NULL); }
+    else { now = strtol(date.chars(), nullptr, 10); }
 
     fputs(ctime(&now), stdout);
 }

apps/ls.cpp

@@ -12,7 +12,7 @@ int main(int argc, char** argv)
     bool show_almost_all;
 
     ArgumentParser parser;
-    parser.add_positional_argument(pathname, "directory", false, "/");
+    parser.add_positional_argument(pathname, "directory", "/");
     parser.add_switch_argument(show_all, 'a', "all");
     parser.add_switch_argument(show_almost_all, 'A', "almost-all");
     parser.parse(argc, argv);

libos/include/os/ArgumentParser.h

@@ -8,10 +8,13 @@ class ArgumentParser
     ArgumentParser() = default;
 
     Result<void> add_positional_argument(StringView& out, StringView name, bool required);
-    Result<void> add_positional_argument(StringView& out, StringView name, bool required, StringView fallback);
+    Result<void> add_positional_argument(StringView& out, StringView name, StringView fallback);
 
     Result<void> add_switch_argument(bool& out, char short_flag, StringView long_flag);
 
+    Result<void> add_value_argument(StringView& out, char short_flag, StringView long_flag, bool value_required);
+    Result<void> add_value_argument(StringView& out, char short_flag, StringView long_flag, StringView fallback);
+
     void parse(int argc, char* const* argv);
 
   private:
@@ -30,6 +33,16 @@ class ArgumentParser
         StringView long_flag;
     };
 
+    struct ValueArgument
+    {
+        StringView* out;
+        char short_flag;
+        StringView long_flag;
+        bool required;
+        StringView fallback;
+    };
+
     Vector<PositionalArgument> m_positional_args;
     Vector<SwitchArgument> m_switch_args;
+    Vector<ValueArgument> m_value_args;
 };

libos/src/ArgumentParser.cpp

@@ -9,10 +9,9 @@ Result<void> ArgumentParser::add_positional_argument(StringView& out, StringView
     return m_positional_args.try_append(move(arg));
 }
 
-Result<void> ArgumentParser::add_positional_argument(StringView& out, StringView name, bool required,
+Result<void> ArgumentParser::add_positional_argument(StringView& out, StringView name, StringView fallback)
-                                                     StringView fallback)
 {
-    PositionalArgument arg { &out, name, required, fallback };
+    PositionalArgument arg { &out, name, false, fallback };
 
     return m_positional_args.try_append(move(arg));
 }
@@ -24,6 +23,22 @@ Result<void> ArgumentParser::add_switch_argument(bool& out, char short_flag, Str
     return m_switch_args.try_append(move(arg));
 }
 
+Result<void> ArgumentParser::add_value_argument(StringView& out, char short_flag, StringView long_flag,
+                                                bool value_required)
+{
+    ValueArgument arg { &out, short_flag, long_flag, value_required, {} };
+
+    return m_value_args.try_append(move(arg));
+}
+
+Result<void> ArgumentParser::add_value_argument(StringView& out, char short_flag, StringView long_flag,
+                                                StringView fallback)
+{
+    ValueArgument arg { &out, short_flag, long_flag, false, fallback };
+
+    return m_value_args.try_append(move(arg));
+}
+
 static bool looks_like_short_flag(StringView arg)
 {
     return arg.length() > 1 && arg[0] == '-';
@@ -38,12 +53,22 @@ void ArgumentParser::parse(int argc, char* const* argv)
 {
     StringView program_name = argv[0];
 
+    Option<ValueArgument> current_value_argument = {};
+    bool is_parsing_value_argument = false;
+
     bool is_still_parsing_flags = true;
 
     for (int i = 1; i < argc; i++)
     {
         StringView arg = argv[i];
 
+        if (is_parsing_value_argument)
+        {
+            *current_value_argument->out = arg;
+            is_parsing_value_argument = false;
+            continue;
+        }
+
         if (is_still_parsing_flags)
         {
             if (arg == "--")
@@ -68,6 +93,17 @@ void ArgumentParser::parse(int argc, char* const* argv)
                     }
                 }
 
+                for (const auto& current : m_value_args)
+                {
+                    if (current.long_flag == flag)
+                    {
+                        current_value_argument = current;
+                        is_parsing_value_argument = true;
+                        found = true;
+                        break;
+                    }
+                }
+
                 if (found) continue;
 
                 fprintf(stderr, "%s: unrecognized option '%s'\n", program_name.chars(), arg.chars());
@@ -81,6 +117,8 @@ void ArgumentParser::parse(int argc, char* const* argv)
                 {
                     bool found = false;
 
+                    // FIXME: Implement value arguments for short flags.
+
                     for (const auto& current : m_switch_args)
                     {
                         if (current.short_flag == ' ') continue;
@@ -113,6 +151,17 @@ void ArgumentParser::parse(int argc, char* const* argv)
         *current->out = arg;
     }
 
+    if (is_parsing_value_argument)
+    {
+        if (current_value_argument->required)
+        {
+            fprintf(stderr, "%s: option '--%s' requires an argument\n", program_name.chars(),
+                    current_value_argument->long_flag.chars());
+            exit(1);
+        }
+        else { *current_value_argument->out = current_value_argument->fallback; }
+    }
+
     // Loop through all remaining positional arguments.
     for (const auto& arg : m_positional_args)
     {