✨ Make the flag parser smarter

It will now allow multiple presence flag aliases to be joined into a single flag, such that `-a -b -c <=> -abc`.

This fixes #75

cloud-core/src/main/java/cloud/commandframework/LockableCommandManager.java

@@ -74,7 +74,7 @@ public abstract class LockableCommandManager<C> extends CommandManager<C> {
      * else {@link IllegalStateException} will be called
      *
      * @param command Command to register
-     * @return
+     * @return The command manager instance
      */
     @Override
     public final @NonNull CommandManager<C> command(final @NonNull Command<C> command) {
@@ -95,7 +95,7 @@ public abstract class LockableCommandManager<C> extends CommandManager<C> {
      * else {@link IllegalStateException} will be called
      *
      * @param command Command to register. {@link Command.Builder#build()}} will be invoked.
-     * @return
+     * @return The command manager instance
      */
     @Override
     public final @NonNull CommandManager<C> command(final Command.@NonNull Builder<C> command) {

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

@@ -39,9 +39,12 @@ import java.util.Collections;
 import java.util.HashSet;
 import java.util.LinkedList;
 import java.util.List;
+import java.util.Locale;
 import java.util.Queue;
 import java.util.Set;
 import java.util.function.BiFunction;
+import java.util.regex.Matcher;
+import java.util.regex.Pattern;
 
 /**
  * Container for flag parsing logic. This should not be be used directly.
@@ -51,6 +54,9 @@ import java.util.function.BiFunction;
  */
 public final class FlagArgument<C> extends CommandArgument<C, Object> {
 
+    private static final Pattern FLAG_ALIAS_PATTERN = Pattern.compile(" -(?<name>([A-Za-z]+))");
+    private static final Pattern FLAG_PRIMARY_PATTERN = Pattern.compile(" --(?<name>([A-Za-z]+))");
+
     /**
      * Dummy object that indicates that flags were parsed successfully
      */
@@ -121,6 +127,39 @@ public final class FlagArgument<C> extends CommandArgument<C, Object> {
                         }
                     } else {
                         final String flagName = string.substring(1);
+                        if (flagName.length() > 1) {
+                            boolean oneAdded = false;
+                            /* This is a multi-alias flag, find all flags that apply */
+                            for (final CommandFlag<?> flag : this.flags) {
+                                if (flag.getCommandArgument() != null) {
+                                    continue;
+                                }
+                                for (final String alias : flag.getAliases()) {
+                                    if (flagName.toLowerCase(Locale.ENGLISH).contains(alias.toLowerCase(Locale.ENGLISH))) {
+                                        if (parsedFlags.contains(flag)) {
+                                            return ArgumentParseResult.failure(new FlagParseException(
+                                                    string,
+                                                    FailureReason.DUPLICATE_FLAG,
+                                                    commandContext
+                                            ));
+                                        }
+                                        parsedFlags.add(flag);
+                                        commandContext.flags().addPresenceFlag(flag);
+                                        oneAdded = true;
+                                        break;
+                                    }
+                                }
+                            }
+                            /* We need to parse at least one flag */
+                            if (!oneAdded) {
+                                return ArgumentParseResult.failure(new FlagParseException(
+                                        string,
+                                        FailureReason.NO_FLAG_STARTED,
+                                        commandContext
+                                ));
+                            }
+                            continue;
+                        } else {
                             for (final CommandFlag<?> flag : this.flags) {
                                 for (final String alias : flag.getAliases()) {
                                     if (alias.equalsIgnoreCase(flagName)) {
@@ -130,6 +169,7 @@ public final class FlagArgument<C> extends CommandArgument<C, Object> {
                                 }
                             }
                         }
+                    }
                     if (currentFlag == null) {
                         return ArgumentParseResult.failure(new FlagParseException(
                                 string,
@@ -196,30 +236,76 @@ public final class FlagArgument<C> extends CommandArgument<C, Object> {
             /* Check if we have a last flag stored */
             final String lastArg = commandContext.getOrDefault(FLAG_META, "");
             if (lastArg.isEmpty() || !lastArg.startsWith("-")) {
-                /* We don't care about the last value and so we expect a flag */
+                final String rawInput = commandContext.getRawInputJoined();
-                final List<String> strings = new LinkedList<>();
+                /* Collection containing all used flags */
+                final List<CommandFlag<?>> usedFlags = new LinkedList<>();
+                /* Find all "primary" flags, using --flag */
+                final Matcher primaryMatcher = FLAG_PRIMARY_PATTERN.matcher(rawInput);
+                while (primaryMatcher.find()) {
+                    final String name = primaryMatcher.group("name");
                     for (final CommandFlag<?> flag : this.flags) {
-                    final String mainFlag = String.format("--%s", flag.getName());
+                        if (flag.getName().equalsIgnoreCase(name)) {
-                    final List<String> rawInput = commandContext.getRawInput();
+                            usedFlags.add(flag);
-                    if (rawInput.contains(mainFlag)) {
-                        continue; /* Flag was already used */
-                    }
-                    final List<String> flagAliases = new LinkedList<>();
-                    boolean flagUsed = false;
-                    for (final String alias : flag.getAliases()) {
-                        final String aliasFlag = String.format("-%s", alias);
-                        if (rawInput.contains(aliasFlag)) {
-                            flagUsed = true;
                             break;
                         }
-                        flagAliases.add(aliasFlag);
                     }
-                    if (flagUsed) {
-                        continue; /* Flag was already used via an alias */
                 }
-
+                /* Find all alias flags */
-                    strings.add(mainFlag);
+                final Matcher aliasMatcher = FLAG_ALIAS_PATTERN.matcher(rawInput);
-                    strings.addAll(flagAliases);
+                while (aliasMatcher.find()) {
+                    final String name = aliasMatcher.group("name");
+                    for (final CommandFlag<?> flag : this.flags) {
+                        for (final String alias : flag.getAliases()) {
+                            /* Aliases are single-char strings */
+                            if (name.contains(alias)) {
+                                usedFlags.add(flag);
+                                break;
+                            }
+                        }
+                    }
+                }
+                /* Suggestions */
+                final List<String> strings = new LinkedList<>();
+                /* Recommend "primary" flags */
+                for (final CommandFlag<?> flag : this.flags) {
+                    if (usedFlags.contains(flag)) {
+                        continue;
+                    }
+                    strings.add(
+                            String.format(
+                                    "--%s",
+                                    flag.getName()
+                            )
+                    );
+                }
+                /* Recommend aliases */
+                final boolean suggestCombined = input.length() > 1 && input.charAt(0) == '-' && input.charAt(1) != '-';
+                for (final CommandFlag<?> flag : this.flags) {
+                    if (usedFlags.contains(flag)) {
+                        continue;
+                    }
+                    for (final String alias : flag.getAliases()) {
+                        if (suggestCombined && flag.getCommandArgument() == null) {
+                            strings.add(
+                                    String.format(
+                                            "%s%s",
+                                            input,
+                                            alias
+                                    )
+                            );
+                        } else {
+                            strings.add(
+                                    String.format(
+                                            "-%s",
+                                            alias
+                                    )
+                            );
+                        }
+                    }
+                }
+                /* If we are suggesting the combined flag, then also suggest the current input */
+                if (suggestCombined) {
+                    strings.add(input);
                 }
                 return strings;
             } else {

cloud-core/src/main/java/cloud/commandframework/arguments/flags/CommandFlag.java

@@ -56,9 +56,9 @@ public final class CommandFlag<T> {
             final @NonNull Description description,
             final @Nullable CommandArgument<?, T> commandArgument
     ) {
-        this.name = name;
+        this.name = Objects.requireNonNull(name, "name cannot be null");
-        this.aliases = aliases;
+        this.aliases = Objects.requireNonNull(aliases, "aliases cannot be null");
-        this.description = description;
+        this.description = Objects.requireNonNull(description, "description cannot be null");
         this.commandArgument = commandArgument;
     }
 
@@ -156,7 +156,8 @@ public final class CommandFlag<T> {
         }
 
         /**
-         * Create a new builder instance using the given flag aliases
+         * Create a new builder instance using the given flag aliases.
+         * These may at most be one character in length
          *
          * @param aliases Flag aliases
          * @return New builder instance
@@ -167,6 +168,14 @@ public final class CommandFlag<T> {
                 if (alias.isEmpty()) {
                     continue;
                 }
+                if (alias.length() > 1) {
+                    throw new IllegalArgumentException(
+                           String.format(
+                                   "Alias '%s' has name longer than one character. This is not allowed",
+                                   alias
+                           )
+                    );
+                }
                 filteredAliases.add(alias);
             }
             return new Builder<>(

cloud-core/src/main/java/cloud/commandframework/context/CommandContext.java

@@ -244,6 +244,16 @@ public final class CommandContext<C> {
         return this.getOrDefault("__raw_input__", new LinkedList<>());
     }
 
+    /**
+     * Get the raw input as a joined string
+     *
+     * @return {@link #getRawInput()} joined with {@code " "} as the delimiter
+     * @since 1.1.0
+     */
+    public @NonNull String getRawInputJoined() {
+        return String.join(" ", this.getRawInput());
+    }
+
     /**
      * Create an argument timing for a specific argument
      *

cloud-core/src/test/java/cloud/commandframework/CommandSuggestionsTest.java

@@ -80,6 +80,12 @@ public class CommandSuggestionsTest {
                         .build())
                 .build());
 
+        manager.command(manager.commandBuilder("flags2")
+                .flag(manager.flagBuilder("first").withAliases("f"))
+                .flag(manager.flagBuilder("second").withAliases("s"))
+                .flag(manager.flagBuilder("third").withAliases("t"))
+                .build());
+
         manager.command(manager.commandBuilder("numbers").argument(IntegerArgument.of("num")));
 
         manager.command(manager.commandBuilder("numberswithmin")
@@ -169,6 +175,15 @@ public class CommandSuggestionsTest {
         final String input3 = "flags 10 --enum foo ";
         final List<String> suggestions3 = manager.suggest(new TestCommandSender(), input3);
         Assertions.assertEquals(Collections.singletonList("--static"), suggestions3);
+        final String input4 = "flags2 ";
+        final List<String> suggestions4 = manager.suggest(new TestCommandSender(), input4);
+        Assertions.assertEquals(Arrays.asList("--first", "--second", "--third", "-f", "-s", "-t"), suggestions4);
+        final String input5 = "flags2 -f";
+        final List<String> suggestions5 = manager.suggest(new TestCommandSender(), input5);
+        Assertions.assertEquals(Arrays.asList("-fs", "-ft", "-f"), suggestions5);
+        final String input6 = "flags2 -f -s";
+        final List<String> suggestions6 = manager.suggest(new TestCommandSender(), input6);
+        Assertions.assertEquals(Arrays.asList("-st", "-s"), suggestions6);
     }
 
     @Test

cloud-core/src/test/java/cloud/commandframework/CommandTreeTest.java

@@ -117,6 +117,7 @@ class CommandTreeTest {
                         .withAliases("t")
                         .build())
                 .flag(manager.flagBuilder("test2")
+                        .withAliases("f")
                         .build())
                 .flag(manager.flagBuilder("num")
                         .withArgument(IntegerArgument.of("num")).build())
@@ -124,6 +125,7 @@ class CommandTreeTest {
                         .withArgument(EnumArgument.of(FlagEnum.class, "enum")))
                 .handler(c -> {
                     System.out.println("Flag present? " + c.flags().isPresent("test"));
+                    System.out.println("Second flag present? " + c.flags().isPresent("test2"));
                     System.out.println("Numerical flag: " + c.flags().getValue("num", -10));
                     System.out.println("Enum: " + c.flags().getValue("enum", FlagEnum.PROXI));
                 })
@@ -283,6 +285,7 @@ class CommandTreeTest {
                 manager.executeCommand(new TestCommandSender(), "flags --test test2").join());
         manager.executeCommand(new TestCommandSender(), "flags --num 500").join();
         manager.executeCommand(new TestCommandSender(), "flags --num 63 --enum potato --test").join();
+        manager.executeCommand(new TestCommandSender(), "flags -tf --num 63 --enum potato").join();
     }
 
     @Test