Refine command programming model

- Introduce command exit status and exception mapper
- Add support for arguments and options
- Remove AST-based command parsing and make the parser swappable
- Simplify command alias type
- Handle command help requests in AbstractCommand
- Add command utilities

Sub commands and aliases are not implemented yet.

Author: fmbenhassine

spring-shell-core/src/main/java/org/springframework/shell/core/EnumValueProvider.java

@@ -48,8 +48,7 @@ default String getDescription() {
 	 * @return the help text of the command
 	 */
 	default String getHelp() {
-		// TODO generate default help from description, options, aliases, etc.
-		return "";
+		return getName() + "(" + String.join(",", getAliases()) + "): " + getDescription();
 	}
 
 	/**
@@ -60,26 +59,19 @@ default String getGroup() {
 		return "";
 	}
 
-	/**
-	 * Get the options of the command.
-	 * @return the options of the command
-	 */
-	default List<CommandOption> getOptions() {
-		return Collections.emptyList();
-	}
-
 	/**
 	 * Get the aliases of the command.
 	 * @return the aliases of the command
 	 */
-	default List<CommandAlias> getAliases() {
+	default List<String> getAliases() {
 		return Collections.emptyList();
 	}
 
 	/**
 	 * Execute the command within the given context.
 	 * @param commandContext the context of the command
+	 * @return the exit status of the command
 	 */
-	void execute(CommandContext commandContext) throws Exception;
+	ExitStatus execute(CommandContext commandContext) throws Exception;
 
 }

spring-shell-core/src/main/java/org/springframework/shell/core/command/ArgumentHeaderMethodArgumentResolver.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2023 the original author or authors.
+ * Copyright 2025-present the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -13,10 +13,14 @@
  * See the License for the specific language governing permissions and
  * limitations under the License.
  */
-package org.springframework.shell.core.command.parser;
+package org.springframework.shell.core.command;
 
-public enum TokenType {
-
-	ARGUMENT, COMMAND, OPTION, DOUBLEDASH, DIRECTIVE
+/**
+ * Record representing a runtime argument to a command.
+ *
+ * @author Mahmoud Ben Hassine
+ * @since 4.0.0
+ */
+public record CommandArgument(int index, String value) {
 
 }

spring-shell-core/src/main/java/org/springframework/shell/core/command/Command.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2022-2024 the original author or authors.
+ * Copyright 2022-present the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -20,12 +20,13 @@
 import org.jline.terminal.Terminal;
 
 /**
- * Interface containing information about current command execution.
+ * Interface containing information about the current command invocation.
  *
  * @author Janne Valkealahti
  * @author Piotr Olaszewski
  * @author Mahmoud Ben Hassine
  */
-public record CommandContext(List<String> rawArgs, CommandRegistry commandRegistry, Terminal terminal) {
+public record CommandContext(List<CommandOption> options, List<CommandArgument> arguments,
+		CommandRegistry commandRegistry, Terminal terminal) {
 
 }