Rework command subsystem

- Focus of these changes are to introduce a new command system based on
  real registrations (new way) instead of continuously (old way) resolve
  methods and its parameters via reflection.
- There's a lot of changes as this resolution via reflection had its
  hooks almost everywhere and thus most changes are just refactorings.
- Order to understand real changes I'd start to look classes under
  `org.springframework.shell.command` package as it defines new registration,
  catalog and parser classes. Also samples contain new classes to demonstrate
  new functionality.
- Fixes #380

spring-shell-autoconfigure/src/main/java/org/springframework/shell/boot/CommandCatalogAutoConfiguration.java

@@ -0,0 +1,58 @@
+/*
+ * Copyright 2021-2022 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.
+ * You may obtain a copy of the License at
+ *
+ *      https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.springframework.shell.boot;
+
+import java.util.List;
+import java.util.stream.Collectors;
+
+import org.springframework.beans.factory.ObjectProvider;
+import org.springframework.boot.autoconfigure.condition.ConditionalOnMissingBean;
+import org.springframework.context.annotation.Bean;
+import org.springframework.context.annotation.Configuration;
+import org.springframework.shell.MethodTargetRegistrar;
+import org.springframework.shell.command.CommandCatalog;
+import org.springframework.shell.command.CommandCatalogCustomizer;
+import org.springframework.shell.command.CommandRegistration;
+import org.springframework.shell.command.CommandResolver;
+
+@Configuration(proxyBeanMethods = false)
+public class CommandCatalogAutoConfiguration {
+
+	@Bean
+	@ConditionalOnMissingBean(CommandCatalog.class)
+	public CommandCatalog commandCatalog(ObjectProvider<MethodTargetRegistrar> methodTargetRegistrars,
+			ObjectProvider<CommandResolver> commandResolvers,
+			ObjectProvider<CommandCatalogCustomizer> commandCatalogCustomizers) {
+		List<CommandResolver> resolvers = commandResolvers.orderedStream().collect(Collectors.toList());
+		CommandCatalog catalog = CommandCatalog.of(resolvers, null);
+		methodTargetRegistrars.orderedStream().forEach(resolver -> {
+			resolver.register(catalog);
+		});
+		commandCatalogCustomizers.orderedStream().forEach(customizer -> {
+			customizer.customize(catalog);
+		});
+		return catalog;
+	}
+
+	@Bean
+	public CommandCatalogCustomizer defaultCommandCatalogCustomizer(ObjectProvider<CommandRegistration> commandRegistrations) {
+		return catalog -> {
+			commandRegistrations.orderedStream().forEach(registration -> {
+				catalog.register(registration);
+			});
+		};
+	}
+}

spring-shell-autoconfigure/src/main/java/org/springframework/shell/boot/CommandRegistryAutoConfiguration.java

@@ -1,39 +0,0 @@
-/*
- * Copyright 2021 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.
- * You may obtain a copy of the License at
- *
- *      https://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
- */
-package org.springframework.shell.boot;
-
-import org.springframework.beans.factory.ObjectProvider;
-import org.springframework.context.annotation.Bean;
-import org.springframework.context.annotation.Configuration;
-import org.springframework.shell.CommandRegistry;
-import org.springframework.shell.ConfigurableCommandRegistry;
-import org.springframework.shell.MethodTargetRegistrar;
-import org.springframework.shell.context.ShellContext;
-
-@Configuration(proxyBeanMethods = false)
-public class CommandRegistryAutoConfiguration {
-
-	@Bean
-	public CommandRegistry commandRegistry(
-			ObjectProvider<MethodTargetRegistrar> methodTargetRegistrars,
-			ShellContext shellContext) {
-		ConfigurableCommandRegistry registry = new ConfigurableCommandRegistry(shellContext);
-		methodTargetRegistrars.orderedStream().forEach(resolver -> {
-			resolver.register(registry);
-		});
-		return registry;
-	}
-}

spring-shell-autoconfigure/src/main/java/org/springframework/shell/boot/LineReaderAutoConfiguration.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2021 the original author or authors.
+ * Copyright 2021-2022 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.
@@ -34,7 +34,7 @@ import org.springframework.context.annotation.Bean;
 import org.springframework.context.annotation.Configuration;
 import org.springframework.context.event.ContextClosedEvent;
 import org.springframework.context.event.EventListener;
-import org.springframework.shell.CommandRegistry;
+import org.springframework.shell.command.CommandCatalog;
 
 @Configuration(proxyBeanMethods = false)
 public class LineReaderAutoConfiguration {
@@ -45,7 +45,7 @@ public class LineReaderAutoConfiguration {
 
 	private Parser parser;
 
-	private CommandRegistry commandRegistry;
+	private CommandCatalog commandRegistry;
 
 	private org.jline.reader.History jLineHistory;
 
@@ -53,7 +53,7 @@ public class LineReaderAutoConfiguration {
 	private String historyPath;
 
 	public LineReaderAutoConfiguration(Terminal terminal, Completer completer, Parser parser,
-			CommandRegistry commandRegistry, org.jline.reader.History jLineHistory) {
+			CommandCatalog commandRegistry, org.jline.reader.History jLineHistory) {
 		this.terminal = terminal;
 		this.completer = completer;
 		this.parser = parser;
@@ -79,7 +79,7 @@ public class LineReaderAutoConfiguration {
 					public AttributedString highlight(LineReader reader, String buffer) {
 						int l = 0;
 						String best = null;
-						for (String command : commandRegistry.listCommands().keySet()) {
+						for (String command : commandRegistry.getRegistrations().keySet()) {
 							if (buffer.startsWith(command) && command.length() > l) {
 								l = command.length();
 								best = command;

spring-shell-autoconfigure/src/main/java/org/springframework/shell/boot/ParameterResolverAutoConfiguration.java

@@ -1,24 +1,35 @@
 package org.springframework.shell.boot;
 
-import java.util.Set;
-import java.util.stream.Collectors;
+import java.util.ArrayList;
+import java.util.List;
 
-import org.springframework.beans.factory.ObjectProvider;
 import org.springframework.context.annotation.Bean;
 import org.springframework.context.annotation.Configuration;
-import org.springframework.core.convert.ConversionService;
-import org.springframework.shell.ParameterResolver;
-import org.springframework.shell.standard.StandardParameterResolver;
-import org.springframework.shell.standard.ValueProvider;
+import org.springframework.core.convert.support.DefaultConversionService;
+import org.springframework.messaging.handler.annotation.support.HeadersMethodArgumentResolver;
+import org.springframework.messaging.handler.invocation.HandlerMethodArgumentResolver;
+import org.springframework.shell.command.ArgumentHeaderMethodArgumentResolver;
+import org.springframework.shell.command.CommandContextMethodArgumentResolver;
+import org.springframework.shell.command.CommandExecution.CommandExecutionHandlerMethodArgumentResolvers;
+import org.springframework.shell.completion.CompletionResolver;
+import org.springframework.shell.completion.DefaultCompletionResolver;
+import org.springframework.shell.standard.ShellOptionMethodArgumentResolver;
 
 @Configuration(proxyBeanMethods = false)
 public class ParameterResolverAutoConfiguration {
 
 	@Bean
-	public ParameterResolver standardParameterResolver(ConversionService conversionService,
-			ObjectProvider<ValueProvider> valueProviders) {
-		Set<ValueProvider> collect = valueProviders.orderedStream().collect(Collectors.toSet());
-		return new StandardParameterResolver(conversionService, collect);
+	public CompletionResolver defaultCompletionResolver() {
+		return new DefaultCompletionResolver();
 	}
 
+	@Bean
+	public CommandExecutionHandlerMethodArgumentResolvers commandExecutionHandlerMethodArgumentResolvers() {
+		List<HandlerMethodArgumentResolver> resolvers = new ArrayList<>();
+		resolvers.add(new ArgumentHeaderMethodArgumentResolver(new DefaultConversionService(), null));
+		resolvers.add(new HeadersMethodArgumentResolver());
+		resolvers.add(new CommandContextMethodArgumentResolver());
+		resolvers.add(new ShellOptionMethodArgumentResolver(new DefaultConversionService(), null));
+		return new CommandExecutionHandlerMethodArgumentResolvers(resolvers);
+	}
 }

spring-shell-autoconfigure/src/main/java/org/springframework/shell/boot/SpringShellAutoConfiguration.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2017-2021 the original author or authors.
+ * Copyright 2017-2022 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.
@@ -18,6 +18,8 @@ package org.springframework.shell.boot;
 
 import java.util.Set;
 
+import org.jline.terminal.Terminal;
+
 import org.springframework.boot.autoconfigure.condition.ConditionalOnMissingBean;
 import org.springframework.boot.convert.ApplicationConversionService;
 import org.springframework.context.ApplicationContext;
@@ -27,10 +29,10 @@ import org.springframework.context.annotation.Import;
 import org.springframework.core.convert.ConversionService;
 import org.springframework.core.convert.support.DefaultConversionService;
 import org.springframework.format.support.FormattingConversionService;
-import org.springframework.shell.CommandRegistry;
 import org.springframework.shell.ResultHandler;
 import org.springframework.shell.ResultHandlerService;
 import org.springframework.shell.Shell;
+import org.springframework.shell.command.CommandCatalog;
 import org.springframework.shell.result.GenericResultHandlerService;
 import org.springframework.shell.result.ResultHandlerConfig;
 
@@ -61,7 +63,7 @@ public class SpringShellAutoConfiguration {
 	}
 
 	@Bean
-	public Shell shell(ResultHandlerService resultHandlerService, CommandRegistry commandRegistry) {
-		return new Shell(resultHandlerService, commandRegistry);
+	public Shell shell(ResultHandlerService resultHandlerService, CommandCatalog commandRegistry, Terminal terminal) {
+		return new Shell(resultHandlerService, commandRegistry, terminal);
 	}
 }

spring-shell-autoconfigure/src/main/java/org/springframework/shell/boot/StandardAPIAutoConfiguration.java

@@ -18,8 +18,8 @@ package org.springframework.shell.boot;
 
 import org.springframework.context.annotation.Bean;
 import org.springframework.context.annotation.Configuration;
-import org.springframework.shell.CommandRegistry;
 import org.springframework.shell.MethodTargetRegistrar;
+import org.springframework.shell.command.CommandCatalog;
 import org.springframework.shell.standard.CommandValueProvider;
 import org.springframework.shell.standard.EnumValueProvider;
 import org.springframework.shell.standard.FileValueProvider;
@@ -35,7 +35,7 @@ import org.springframework.shell.standard.ValueProvider;
 public class StandardAPIAutoConfiguration {
 
 	@Bean
-	public ValueProvider commandValueProvider(CommandRegistry commandRegistry) {
+	public ValueProvider commandValueProvider(CommandCatalog commandRegistry) {
 		return new CommandValueProvider(commandRegistry);
 	}
 

spring-shell-autoconfigure/src/main/resources/META-INF/spring.factories

@@ -3,7 +3,7 @@ org.springframework.shell.boot.ShellContextAutoConfiguration,\
 org.springframework.shell.boot.SpringShellAutoConfiguration,\
 org.springframework.shell.boot.ShellRunnerAutoConfiguration,\
 org.springframework.shell.boot.ApplicationRunnerAutoConfiguration,\
-org.springframework.shell.boot.CommandRegistryAutoConfiguration,\
+org.springframework.shell.boot.CommandCatalogAutoConfiguration,\
 org.springframework.shell.boot.LineReaderAutoConfiguration,\
 org.springframework.shell.boot.CompleterAutoConfiguration,\
 org.springframework.shell.boot.JLineAutoConfiguration,\

spring-shell-autoconfigure/src/test/java/org/springframework/shell/boot/CommandCatalogAutoConfigurationTests.java

@@ -0,0 +1,106 @@
+/*
+ * Copyright 2022 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.
+ * You may obtain a copy of the License at
+ *
+ *      https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.springframework.shell.boot;
+
+import java.util.Collections;
+
+import org.assertj.core.api.InstanceOfAssertFactories;
+import org.junit.jupiter.api.Test;
+
+import org.springframework.boot.autoconfigure.AutoConfigurations;
+import org.springframework.boot.test.context.runner.ApplicationContextRunner;
+import org.springframework.context.annotation.Bean;
+import org.springframework.context.annotation.Configuration;
+import org.springframework.shell.command.CommandCatalog;
+import org.springframework.shell.command.CommandRegistration;
+import org.springframework.shell.command.CommandResolver;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+public class CommandCatalogAutoConfigurationTests {
+
+	private final ApplicationContextRunner contextRunner = new ApplicationContextRunner()
+			.withConfiguration(AutoConfigurations.of(CommandCatalogAutoConfiguration.class));
+
+	@Test
+	void defaultCommandCatalog() {
+		this.contextRunner.run((context) -> assertThat(context).hasSingleBean(CommandCatalog.class));
+	}
+
+	@Test
+	void testCommandResolvers() {
+		this.contextRunner.withUserConfiguration(CustomCommandResolverConfiguration.class)
+				.run((context) -> {
+					CommandCatalog commandCatalog = context.getBean(CommandCatalog.class);
+					assertThat(commandCatalog).extracting("resolvers").asInstanceOf(InstanceOfAssertFactories.LIST)
+							.hasSize(1);
+				});
+	}
+
+	@Test
+	void customCommandCatalog() {
+		this.contextRunner.withUserConfiguration(CustomCommandCatalogConfiguration.class)
+				.run((context) -> {
+					CommandCatalog commandCatalog = context.getBean(CommandCatalog.class);
+					assertThat(commandCatalog).isSameAs(CustomCommandCatalogConfiguration.testCommandCatalog);
+				});
+	}
+
+	@Test
+	void registerCommandRegistration() {
+		this.contextRunner.withUserConfiguration(CustomCommandRegistrationConfiguration.class)
+				.run((context) -> {
+					CommandCatalog commandCatalog = context.getBean(CommandCatalog.class);
+					assertThat(commandCatalog.getRegistrations().get("customcommand")).isNotNull();
+				});
+	}
+
+	@Configuration
+	static class CustomCommandResolverConfiguration {
+
+		@Bean
+		CommandResolver customCommandResolver() {
+			return () -> Collections.emptyList();
+		}
+	}
+
+	@Configuration
+	static class CustomCommandCatalogConfiguration {
+
+		static final CommandCatalog testCommandCatalog = CommandCatalog.of();
+
+		@Bean
+		CommandCatalog customCommandCatalog() {
+			return testCommandCatalog;
+		}
+	}
+
+	@Configuration
+	static class CustomCommandRegistrationConfiguration {
+
+		@Bean
+		CommandRegistration commandRegistration() {
+			return CommandRegistration.builder()
+				.command("customcommand")
+				.withTarget()
+					.function(ctx -> {
+						return null;
+					})
+					.and()
+				.build();
+		}
+	}
+}

spring-shell-autoconfigure/src/test/java/org/springframework/shell/boot/ShellRunnerAutoConfigurationTests.java

@@ -22,8 +22,9 @@ import org.junit.jupiter.api.Test;
 
 import org.springframework.boot.autoconfigure.AutoConfigurations;
 import org.springframework.boot.test.context.runner.ApplicationContextRunner;
-import org.springframework.shell.ParameterResolver;
 import org.springframework.shell.Shell;
+import org.springframework.shell.command.CommandExecution.CommandExecutionHandlerMethodArgumentResolvers;
+import org.springframework.shell.completion.CompletionResolver;
 import org.springframework.shell.context.ShellContext;
 import org.springframework.shell.jline.InteractiveShellRunner;
 import org.springframework.shell.jline.NonInteractiveShellRunner;
@@ -46,7 +47,8 @@ class ShellRunnerAutoConfigurationTests {
 			.withBean(LineReader.class, () -> mock(LineReader.class))
 			.withBean(Parser.class, () -> mock(Parser.class))
 			.withBean(ShellContext.class, () -> mock(ShellContext.class))
-			.withBean(ParameterResolver.class, () -> mock(ParameterResolver.class));
+			.withBean(CompletionResolver.class, () -> mock(CompletionResolver.class))
+			.withBean(CommandExecutionHandlerMethodArgumentResolvers.class, () -> mock(CommandExecutionHandlerMethodArgumentResolvers.class));
 
 	@Nested
 	class Interactive {