✨ Improve syntax hinting for flags

cloud-core/src/main/java/cloud/commandframework/arguments/StandardCommandSyntaxFormatter.java

@@ -25,6 +25,8 @@ package cloud.commandframework.arguments;
 
 import cloud.commandframework.CommandTree;
 import cloud.commandframework.arguments.compound.CompoundArgument;
+import cloud.commandframework.arguments.compound.FlagArgument;
+import cloud.commandframework.arguments.flags.CommandFlag;
 import org.checkerframework.checker.nullness.qual.NonNull;
 import org.checkerframework.checker.nullness.qual.Nullable;
 
@@ -66,10 +68,27 @@ public class StandardCommandSyntaxFormatter<C> implements CommandSyntaxFormatter
                         }
                     }
                     stringBuilder.append(suffix);
-                } else if (commandArgument.isRequired()) {
-                    stringBuilder.append("<").append(commandArgument.getName()).append(">");
                 } else {
-                    stringBuilder.append("[").append(commandArgument.getName()).append("]");
+                    String name = commandArgument.getName();
+
+                    if (commandArgument instanceof FlagArgument) {
+                        final StringBuilder flagBuilder = new StringBuilder();
+                        @SuppressWarnings("unchecked")
+                        final Iterator<CommandFlag<?>> flagIterator = ((FlagArgument<C>) commandArgument).getFlags().iterator();
+                        while (flagIterator.hasNext()) {
+                            flagBuilder.append("--").append(flagIterator.next().getName());
+                            if (flagIterator.hasNext()) {
+                                flagBuilder.append(" | ");
+                            }
+                        }
+                        name = flagBuilder.toString();
+                    }
+
+                    if (commandArgument.isRequired()) {
+                        stringBuilder.append("<").append(name).append(">");
+                    } else {
+                        stringBuilder.append("[").append(name).append("]");
+                    }
                 }
             }
             if (iterator.hasNext()) {
@@ -115,6 +134,20 @@ public class StandardCommandSyntaxFormatter<C> implements CommandSyntaxFormatter
                     }
                 }
                 stringBuilder.append(suffix);
+            } else if (argument instanceof FlagArgument) {
+                final StringBuilder flagBuilder = new StringBuilder();
+                @SuppressWarnings("unchecked")
+                final Iterator<CommandFlag<?>> flagIterator = ((FlagArgument<C>) argument).getFlags().iterator();
+                while (flagIterator.hasNext()) {
+                    flagBuilder.append("--").append(flagIterator.next().getName());
+                    if (flagIterator.hasNext()) {
+                        flagBuilder.append(" | ");
+                    }
+                }
+                stringBuilder.append(" ")
+                             .append(prefix)
+                             .append(flagBuilder)
+                             .append(suffix);
             } else {
                 stringBuilder.append(" ")
                              .append(prefix)

cloud-core/src/main/java/cloud/commandframework/arguments/compound/FlagArgument.java

@@ -45,7 +45,7 @@ import java.util.function.BiFunction;
  *
  * @param <C> Command sender type
  */
-public class FlagArgument<C> extends CommandArgument<C, Object> {
+public final class FlagArgument<C> extends CommandArgument<C, Object> {
 
     /**
      * Dummy object that indicates that flags were parsed successfully
@@ -58,6 +58,7 @@ public class FlagArgument<C> extends CommandArgument<C, Object> {
 
     private static final String FLAG_ARGUMENT_NAME = "flags";
 
+    private final Collection<@NonNull CommandFlag<?>> flags;
     /**
      * Construct a new flag argument
      *
@@ -68,8 +69,19 @@ public class FlagArgument<C> extends CommandArgument<C, Object> {
               FLAG_ARGUMENT_NAME,
               new FlagArgumentParser<>(flags.toArray(new CommandFlag<?>[0])),
               Object.class);
+        this.flags = flags;
     }
 
+    /**
+     * Get the flags registered in the argument
+     *
+     * @return Unmodifiable view of flags
+     */
+    public @NonNull Collection<@NonNull CommandFlag<?>> getFlags() {
+        return Collections.unmodifiableCollection(this.flags);
+    }
+
+
     public static final class FlagArgumentParser<C> implements ArgumentParser<C, Object> {
 
         private final CommandFlag<?>[] flags;