Implement interactive completion

- This is a re-implementation of a interactive completion
  with breaking changes as it moves away from a direct use
  of a MethodParameter in favour of a CommandRegistration
  and its option definitions.
- Fixes #449

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

@@ -52,7 +52,7 @@ public class CompleterAutoConfiguration {
 		public void complete(LineReader reader, ParsedLine line, List<Candidate> candidates) {
 			CompletingParsedLine cpl = (line instanceof CompletingParsedLine) ? ((CompletingParsedLine) line) : t -> t;
 
-			CompletionContext context = new CompletionContext(sanitizeInput(line.words()), line.wordIndex(), line.wordCursor());
+			CompletionContext context = new CompletionContext(sanitizeInput(line.words()), line.wordIndex(), line.wordCursor(), null, null);
 
 			List<CompletionProposal> proposals = shell.complete(context);
 			proposals.stream()

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

@@ -20,6 +20,9 @@ import java.util.ArrayList;
 import java.util.List;
 import java.util.stream.Collectors;
 
+import org.springframework.shell.command.CommandOption;
+import org.springframework.shell.command.CommandRegistration;
+
 /**
  * Represents the buffer context in which completion was triggered.
  *
@@ -33,16 +36,22 @@ public class CompletionContext {
 
 	private final int position;
 
+	private final CommandOption commandOption;
+
+	private final CommandRegistration commandRegistration;
+
 	/**
 	 *
 	 * @param words words in the buffer, excluding words for the command name
 	 * @param wordIndex the index of the word the cursor is in
 	 * @param position the position inside the current word where the cursor is
 	 */
-	public CompletionContext(List<String> words, int wordIndex, int position) {
+	public CompletionContext(List<String> words, int wordIndex, int position, CommandRegistration commandRegistration,  CommandOption commandOption) {
 		this.words = words;
 		this.wordIndex = wordIndex;
 		this.position = position;
+		this.commandRegistration = commandRegistration;
+		this.commandOption = commandOption;
 	}
 
 	public List<String> getWords() {
@@ -57,6 +66,14 @@ public class CompletionContext {
 		return position;
 	}
 
+	public CommandOption getCommandOption() {
+		return commandOption;
+	}
+
+	public CommandRegistration getCommandRegistration() {
+		return commandRegistration;
+	}
+
 	public String upToCursor() {
 		String start = words.subList(0, wordIndex).stream().collect(Collectors.joining(" "));
 		if (wordIndex < words.size()) {
@@ -84,6 +101,11 @@ public class CompletionContext {
 	 * Return a copy of this context, as if the first {@literal nbWords} were not present
 	 */
 	public CompletionContext drop(int nbWords) {
-		return new CompletionContext(new ArrayList<String>(words.subList(nbWords, words.size())), wordIndex-nbWords, position);
+		return new CompletionContext(new ArrayList<String>(words.subList(nbWords, words.size())), wordIndex - nbWords,
+				position, commandRegistration, commandOption);
+	}
+
+	public CompletionContext commandOption(CommandOption commandOption) {
+		return new CompletionContext(words, wordIndex, position, commandRegistration, commandOption);
 	}
 }

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

@@ -22,6 +22,7 @@ import java.util.List;
 import java.util.Optional;
 import java.util.function.Function;
 import java.util.stream.Collectors;
+import java.util.stream.Stream;
 
 import javax.validation.Validator;
 import javax.validation.ValidatorFactory;
@@ -38,6 +39,7 @@ import org.springframework.core.convert.support.DefaultConversionService;
 import org.springframework.shell.command.CommandAlias;
 import org.springframework.shell.command.CommandCatalog;
 import org.springframework.shell.command.CommandExecution;
+import org.springframework.shell.command.CommandOption;
 import org.springframework.shell.command.CommandExecution.CommandExecutionException;
 import org.springframework.shell.command.CommandExecution.CommandExecutionHandlerMethodArgumentResolvers;
 import org.springframework.shell.command.CommandRegistration;
@@ -45,6 +47,7 @@ import org.springframework.shell.completion.CompletionResolver;
 import org.springframework.shell.context.InteractionMode;
 import org.springframework.shell.context.ShellContext;
 import org.springframework.shell.exit.ExitCodeMappings;
+import org.springframework.util.StringUtils;
 
 /**
  * Main class implementing a shell loop.
@@ -275,17 +278,83 @@ public class Shell {
 		String best = findLongestCommand(prefix);
 		if (best != null) {
 			CompletionContext argsContext = context.drop(best.split(" ").length);
-			// Try to complete arguments
 			CommandRegistration registration = commandRegistry.getRegistrations().get(best);
 
 			for (CompletionResolver resolver : completionResolvers) {
 				List<CompletionProposal> resolved = resolver.resolve(registration, argsContext);
 				candidates.addAll(resolved);
 			}
+
+			// Try to complete arguments
+			List<CommandOption> matchedArgOptions = new ArrayList<>();
+			if (argsContext.getWords().size() > 0) {
+				matchedArgOptions.addAll(matchOptions(registration.getOptions(), argsContext.getWords().get(0)));
+			}
+
+			List<CompletionProposal> argProposals =	matchedArgOptions.stream()
+				.flatMap(o -> {
+					Function<CompletionContext, List<CompletionProposal>> completion = o.getCompletion();
+					if (completion != null) {
+						List<CompletionProposal> apply = completion.apply(argsContext.commandOption(o));
+						return apply.stream();
+					}
+					return Stream.empty();
+				})
+				.collect(Collectors.toList());
+
+			candidates.addAll(argProposals);
 		}
 		return candidates;
 	}
 
+	private List<CommandOption> matchOptions(List<CommandOption> options, String arg) {
+		List<CommandOption> matched = new ArrayList<>();
+		String trimmed = StringUtils.trimLeadingCharacter(arg, '-');
+		int count = arg.length() - trimmed.length();
+		if (count == 1) {
+			if (trimmed.length() == 1) {
+				Character trimmedChar = trimmed.charAt(0);
+				options.stream()
+					.filter(o -> {
+						for (Character sn : o.getShortNames()) {
+							if (trimmedChar.equals(sn)) {
+								return true;
+							}
+						}
+						return false;
+					})
+				.findFirst()
+				.ifPresent(o -> matched.add(o));
+			}
+			else if (trimmed.length() > 1) {
+				trimmed.chars().mapToObj(i -> (char)i)
+					.forEach(c -> {
+						options.stream().forEach(o -> {
+							for (Character sn : o.getShortNames()) {
+								if (c.equals(sn)) {
+									matched.add(o);
+								}
+							}
+						});
+					});
+			}
+		}
+		else if (count == 2) {
+			options.stream()
+				.filter(o -> {
+					for (String ln : o.getLongNames()) {
+						if (trimmed.equals(ln)) {
+							return true;
+						}
+					}
+					return false;
+				})
+				.findFirst()
+				.ifPresent(o -> matched.add(o));
+		}
+		return matched;
+	}
+
 	private List<CompletionProposal> commandsStartingWith(String prefix) {
 		// Workaround for https://github.com/spring-projects/spring-shell/issues/150
 		// (sadly, this ties this class to JLine somehow)

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

@@ -15,7 +15,12 @@
  */
 package org.springframework.shell.command;
 
+import java.util.List;
+import java.util.function.Function;
+
 import org.springframework.core.ResolvableType;
+import org.springframework.shell.CompletionContext;
+import org.springframework.shell.CompletionProposal;
 
 /**
  * Interface representing an option in a command.
@@ -94,6 +99,13 @@ public interface CommandOption {
 	 */
 	String getLabel();
 
+	/**
+	 * Gets a completion function.
+	 *
+	 * @return the completion function
+	 */
+	Function<CompletionContext, List<CompletionProposal>> getCompletion();
+
 	/**
 	 * Gets an instance of a default {@link CommandOption}.
 	 *
@@ -103,7 +115,7 @@ public interface CommandOption {
 	 * @return default command option
 	 */
 	public static CommandOption of(String[] longNames, Character[] shortNames, String description) {
-		return of(longNames, shortNames, description, null, false, null, null, null, null, null);
+		return of(longNames, shortNames, description, null, false, null, null, null, null, null, null);
 	}
 
 	/**
@@ -117,7 +129,7 @@ public interface CommandOption {
 	 */
 	public static CommandOption of(String[] longNames, Character[] shortNames, String description,
 			ResolvableType type) {
-		return of(longNames, shortNames, description, type, false, null, null, null, null, null);
+		return of(longNames, shortNames, description, type, false, null, null, null, null, null, null);
 	}
 
 	/**
@@ -133,13 +145,14 @@ public interface CommandOption {
 	 * @param arityMin the min arity
 	 * @param arityMax the max arity
 	 * @param label the label
+	 * @param completion the completion
 	 * @return default command option
 	 */
 	public static CommandOption of(String[] longNames, Character[] shortNames, String description,
 			ResolvableType type, boolean required, String defaultValue, Integer position, Integer arityMin,
-			Integer arityMax, String label) {
+			Integer arityMax, String label, Function<CompletionContext, List<CompletionProposal>> completion) {
 		return new DefaultCommandOption(longNames, shortNames, description, type, required, defaultValue, position,
-				arityMin, arityMax, label);
+				arityMin, arityMax, label, completion);
 	}
 
 	/**
@@ -157,10 +170,12 @@ public interface CommandOption {
 		private int arityMin;
 		private int arityMax;
 		private String label;
+		private Function<CompletionContext, List<CompletionProposal>> completion;
 
 		public DefaultCommandOption(String[] longNames, Character[] shortNames, String description,
 				ResolvableType type, boolean required, String defaultValue, Integer position,
-				Integer arityMin, Integer arityMax, String label) {
+				Integer arityMin, Integer arityMax, String label,
+				Function<CompletionContext, List<CompletionProposal>> completion) {
 			this.longNames = longNames != null ? longNames : new String[0];
 			this.shortNames = shortNames != null ? shortNames : new Character[0];
 			this.description = description;
@@ -171,6 +186,7 @@ public interface CommandOption {
 			this.arityMin = arityMin != null ? arityMin : -1;
 			this.arityMax = arityMax != null ? arityMax : -1;
 			this.label = label;
+			this.completion = completion;
 		}
 
 		@Override
@@ -222,5 +238,10 @@ public interface CommandOption {
 		public String getLabel() {
 			return label;
 		}
+
+		@Override
+		public Function<CompletionContext, List<CompletionProposal>> getCompletion() {
+			return completion;
+		}
 	}
 }

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

@@ -29,6 +29,8 @@ import java.util.stream.Stream;
 import org.springframework.core.ResolvableType;
 import org.springframework.lang.Nullable;
 import org.springframework.shell.Availability;
+import org.springframework.shell.CompletionContext;
+import org.springframework.shell.CompletionProposal;
 import org.springframework.shell.context.InteractionMode;
 import org.springframework.util.Assert;
 import org.springframework.util.ObjectUtils;
@@ -208,6 +210,14 @@ public interface CommandRegistration {
 		 */
 		OptionSpec label(String label);
 
+		/**
+		 * Define a {@code completion function} for an option.
+		 *
+		 * @param completion the completion function
+		 * @return option spec for chaining
+		 */
+		OptionSpec completion(Function<CompletionContext, List<CompletionProposal>> completion);
+
 		/**
 		 * Return a builder for chaining.
 		 *
@@ -528,6 +538,7 @@ public interface CommandRegistration {
 		private Integer arityMin;
 		private Integer arityMax;
 		private String label;
+		private Function<CompletionContext, List<CompletionProposal>> completion;
 
 		DefaultOptionSpec(BaseBuilder builder) {
 			this.builder = builder;
@@ -626,6 +637,12 @@ public interface CommandRegistration {
 			return this;
 		}
 
+		@Override
+		public OptionSpec completion(Function<CompletionContext, List<CompletionProposal>> completion) {
+			this.completion = completion;
+			return this;
+		}
+
 		@Override
 		public Builder and() {
 			return builder;
@@ -670,6 +687,10 @@ public interface CommandRegistration {
 		public String getLabel() {
 			return label;
 		}
+
+		public Function<CompletionContext, List<CompletionProposal>> getCompletion() {
+			return completion;
+		}
 	}
 
 	static class DefaultTargetSpec implements TargetSpec {
@@ -840,7 +861,7 @@ public interface CommandRegistration {
 			return optionSpecs.stream()
 				.map(o -> CommandOption.of(o.getLongNames(), o.getShortNames(), o.getDescription(), o.getType(),
 						o.isRequired(), o.getDefaultValue(), o.getPosition(), o.getArityMin(), o.getArityMax(),
-						o.getLabel()))
+						o.getLabel(), o.getCompletion()))
 				.collect(Collectors.toList());
 		}
 

spring-shell-core/src/test/java/org/springframework/shell/ShellTests.java

@@ -224,37 +224,37 @@ public class ShellTests {
 		when(commandRegistry.getRegistrations()).thenReturn(registrations);
 
 		// Invoke at very start
-		List<String> proposals = shell.complete(new CompletionContext(Arrays.asList(""), 0, "".length()))
+		List<String> proposals = shell.complete(new CompletionContext(Arrays.asList(""), 0, "".length(), null, null))
 				.stream().map(CompletionProposal::value).collect(Collectors.toList());
 		assertThat(proposals).containsExactlyInAnyOrder("another command", "hello world");
 
 		// Invoke in middle of first word
-		proposals = shell.complete(new CompletionContext(Arrays.asList("hel"), 0, "hel".length()))
+		proposals = shell.complete(new CompletionContext(Arrays.asList("hel"), 0, "hel".length(), null, null))
 				.stream().map(CompletionProposal::value).collect(Collectors.toList());
 		assertThat(proposals).containsExactly("hello world");
 
 		// Invoke at end of first word (no space after yet)
-		proposals = shell.complete(new CompletionContext(Arrays.asList("hello"), 0, "hello".length()))
+		proposals = shell.complete(new CompletionContext(Arrays.asList("hello"), 0, "hello".length(), null, null))
 				.stream().map(CompletionProposal::value).collect(Collectors.toList());
 		assertThat(proposals).containsExactly("hello world");
 
 		// Invoke after first word / start of second word
-		proposals = shell.complete(new CompletionContext(Arrays.asList("hello", ""), 1, "".length()))
+		proposals = shell.complete(new CompletionContext(Arrays.asList("hello", ""), 1, "".length(), null, null))
 				.stream().map(CompletionProposal::value).collect(Collectors.toList());
 		assertThat(proposals).containsExactly("world");
 
 		// Invoke in middle of second word
-		proposals = shell.complete(new CompletionContext(Arrays.asList("hello", "wo"), 1, "wo".length()))
+		proposals = shell.complete(new CompletionContext(Arrays.asList("hello", "wo"), 1, "wo".length(), null, null))
 				.stream().map(CompletionProposal::value).collect(Collectors.toList());
 		assertThat(proposals).containsExactly("world");
 
 		// Invoke at end of whole command (no space after yet)
-		proposals = shell.complete(new CompletionContext(Arrays.asList("hello", "world"), 1, "world".length()))
+		proposals = shell.complete(new CompletionContext(Arrays.asList("hello", "world"), 1, "world".length(), null, null))
 				.stream().map(CompletionProposal::value).collect(Collectors.toList());
 		assertThat(proposals).containsExactly("world");
 
 		// Invoke in middle of second word
-		proposals = shell.complete(new CompletionContext(Arrays.asList("hello", "world", ""), 2, "".length()))
+		proposals = shell.complete(new CompletionContext(Arrays.asList("hello", "world", ""), 2, "".length(), null, null))
 				.stream().map(CompletionProposal::value).collect(Collectors.toList());
 		assertThat(proposals).isEmpty();
 	}
@@ -287,7 +287,7 @@ public class ShellTests {
 		registrations.put("hello world", registration1);
 		when(commandRegistry.getRegistrations()).thenReturn(registrations);
 
-		List<String> proposals = shell.complete(new CompletionContext(Arrays.asList("hello", "world", ""), 2, "".length()))
+		List<String> proposals = shell.complete(new CompletionContext(Arrays.asList("hello", "world", ""), 2, "".length(), null, null))
 				.stream().map(CompletionProposal::value).collect(Collectors.toList());
 		assertThat(proposals).containsExactlyInAnyOrder("--arg1");
 	}
@@ -311,7 +311,7 @@ public class ShellTests {
 		registrations.put("hello world", registration1);
 		when(commandRegistry.getRegistrations()).thenReturn(registrations);
 
-		List<String> proposals = shell.complete(new CompletionContext(Arrays.asList("hello", "world", ""), 2, "".length()))
+		List<String> proposals = shell.complete(new CompletionContext(Arrays.asList("hello", "world", ""), 2, "".length(), null, null))
 				.stream().map(CompletionProposal::value).collect(Collectors.toList());
 		assertThat(proposals).containsExactlyInAnyOrder("--arg1");
 	}

spring-shell-core/src/test/java/org/springframework/shell/command/CommandParserTests.java

@@ -327,7 +327,7 @@ public class CommandParserTests extends AbstractCommandTests {
 	public void testBooleanWithDefault() {
 		ResolvableType type = ResolvableType.forType(boolean.class);
 		CommandOption option1 = CommandOption.of(new String[] { "arg1" }, new Character[0], "description", type, false,
-				"true", null, null, null, null);
+				"true", null, null, null, null, null);
 
 		List<CommandOption> options = Arrays.asList(option1);
 		String[] args = new String[]{};
@@ -359,7 +359,7 @@ public class CommandParserTests extends AbstractCommandTests {
 
 	private static CommandOption longOption(String name, ResolvableType type, boolean required, Integer position, Integer arityMin, Integer arityMax) {
 		return CommandOption.of(new String[] { name }, new Character[0], "desc", type, required, null, position,
-				arityMin, arityMax, null);
+				arityMin, arityMax, null, null);
 	}
 
 	private static CommandOption shortOption(char name) {

spring-shell-core/src/test/java/org/springframework/shell/command/CommandRegistrationTests.java

@@ -15,6 +15,8 @@
  */
 package org.springframework.shell.command;
 
+import java.util.ArrayList;
+
 import org.junit.jupiter.api.Test;
 
 import org.springframework.core.ResolvableType;
@@ -434,4 +436,23 @@ public class CommandRegistrationTests extends AbstractCommandTests {
 		assertThat(registration.getAvailability()).isNotNull();
 		assertThat(registration.getAvailability().isAvailable()).isFalse();
 	}
+
+	@Test
+	public void testOptionWithCompletion() {
+		CommandRegistration registration;
+		registration = CommandRegistration.builder()
+			.command("command1")
+			.withOption()
+				.longNames("arg1")
+				.completion(ctx -> {
+					return new ArrayList<>();
+				})
+				.and()
+			.withTarget()
+				.function(function1)
+				.and()
+			.build();
+		assertThat(registration.getOptions()).hasSize(1);
+		assertThat(registration.getOptions().get(0).getCompletion()).isNotNull();
+	}
 }

spring-shell-samples/src/main/java/org/springframework/shell/samples/standard/Commands.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2015 the original author or authors.
+ * Copyright 2015-2022 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.
@@ -20,18 +20,12 @@ import java.lang.annotation.ElementType;
 import java.util.Arrays;
 import java.util.Iterator;
 import java.util.List;
-import java.util.stream.Collectors;
 
-import org.springframework.core.MethodParameter;
-import org.springframework.shell.CompletionContext;
-import org.springframework.shell.CompletionProposal;
+import javax.validation.constraints.Size;
+
 import org.springframework.shell.standard.ShellComponent;
 import org.springframework.shell.standard.ShellMethod;
 import org.springframework.shell.standard.ShellOption;
-import org.springframework.shell.standard.ValueProviderSupport;
-import org.springframework.stereotype.Component;
-
-import javax.validation.constraints.Size;
 
 /**
  * Example commands for the Shell 2 Standard resolver.
@@ -61,11 +55,6 @@ public class Commands {
 		System.out.println("You passed " + force);
 	}
 
-	@ShellMethod("Test completion of special values.")
-	public void quote(@ShellOption(valueProvider = FunnyValuesProvider.class) String text) {
-		System.out.println("You said " + text);
-	}
-
 	@ShellMethod("Add numbers.")
 	public int add(int a, int b, int c) {
 		return a + b + c;
@@ -98,24 +87,3 @@ public class Commands {
 		return iterable;
 	}
 }
-
-/**
- * A {@link org.springframework.shell.standard.ValueProvider} that emits values with special characters
- * (quotes, escapes, <em>etc.</em>)
- *
- * @author Eric Bottard
- */
-@Component
-class FunnyValuesProvider extends ValueProviderSupport {
-
-	private final static String[] VALUES = new String[] {
-		"hello world",
-		"I'm quoting \"The Daily Mail\"",
-		"10 \\ 3 = 3"
-	};
-
-	@Override
-	public List<CompletionProposal> complete(MethodParameter parameter, CompletionContext completionContext, String[] hints) {
-		return Arrays.stream(VALUES).map(CompletionProposal::new).collect(Collectors.toList());
-	}
-}

spring-shell-samples/src/main/java/org/springframework/shell/samples/standard/CompleteCommands.java

@@ -0,0 +1,123 @@
+/*
+ * 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.samples.standard;
+
+import java.util.Arrays;
+import java.util.List;
+import java.util.stream.Collectors;
+
+import org.springframework.context.annotation.Bean;
+import org.springframework.shell.CompletionContext;
+import org.springframework.shell.CompletionProposal;
+import org.springframework.shell.command.CommandRegistration;
+import org.springframework.shell.standard.EnumValueProvider;
+import org.springframework.shell.standard.ShellComponent;
+import org.springframework.shell.standard.ShellMethod;
+import org.springframework.shell.standard.ShellOption;
+import org.springframework.shell.standard.ValueProvider;
+
+@ShellComponent
+public class CompleteCommands {
+
+	@Bean
+	CommandRegistration completeCommandRegistration1() {
+		return CommandRegistration.builder()
+			.command("complete", "sample1")
+			.description("complete sample1")
+			.group("Complete Commands")
+			.withOption()
+				.longNames("arg1")
+				.completion(ctx -> {
+					CompletionProposal p1 = new CompletionProposal("arg1hi1");
+					CompletionProposal p2 = new CompletionProposal("arg1hi2");
+					return Arrays.asList(p1, p2);
+				})
+				.and()
+			.withOption()
+				.longNames("arg2")
+				.completion(ctx -> {
+					CompletionProposal p1 = new CompletionProposal("arg2hi1");
+					CompletionProposal p2 = new CompletionProposal("arg2hi2");
+					return Arrays.asList(p1, p2);
+				})
+				.and()
+			.withTarget()
+				.function(ctx -> {
+					String arg1 = ctx.getOptionValue("arg1");
+					return String.format("hi, arg1 value is '%s'", arg1);
+				})
+				.and()
+			.build();
+	}
+
+	@ShellMethod(value = "complete sample2", key = "complete sample2")
+	public String completeCommandSample2(@ShellOption(valueProvider = FunnyValuesProvider.class) String arg1) {
+		return "You said " + arg1;
+	}
+
+	@Bean
+	FunnyValuesProvider funnyValuesProvider() {
+		return new FunnyValuesProvider();
+	}
+
+	static class FunnyValuesProvider implements ValueProvider {
+
+		private final static String[] VALUES = new String[] {
+			"hello world",
+			"I am quoting \"The Daily Mail\"",
+			"10 \\ 3 = 3"
+		};
+
+		@Override
+		public List<CompletionProposal> complete(CompletionContext completionContext) {
+			return Arrays.stream(VALUES).map(CompletionProposal::new).collect(Collectors.toList());
+		}
+	}
+
+	@Bean
+	CommandRegistration completeCommandRegistration3() {
+		return CommandRegistration.builder()
+			.command("complete", "sample3")
+			.description("complete sample3")
+			.group("Complete Commands")
+			.withOption()
+				.longNames("arg1")
+				.type(MyEnums.class)
+				.completion(ctx -> {
+					CompletionProposal p1 = new CompletionProposal(MyEnums.E1.toString());
+					CompletionProposal p2 = new CompletionProposal(MyEnums.E2.toString());
+					CompletionProposal p3 = new CompletionProposal(MyEnums.E3.toString());
+					return Arrays.asList(p1, p2, p3);
+				})
+				.and()
+			.withTarget()
+				.function(ctx -> {
+					String arg1 = ctx.getOptionValue("arg1");
+					return String.format("You said '%s'", arg1);
+				})
+				.and()
+			.build();
+	}
+
+	@ShellMethod(value = "complete sample4", key = "complete sample4")
+	public String completeCommandSample4(@ShellOption(valueProvider = EnumValueProvider.class) MyEnums arg1) {
+		return "You said " + arg1;
+	}
+
+	static enum MyEnums {
+		E1, E2, E3
+	}
+}

spring-shell-standard/src/main/java/org/springframework/shell/standard/CommandValueProvider.java

@@ -19,7 +19,6 @@ package org.springframework.shell.standard;
 import java.util.List;
 import java.util.stream.Collectors;
 
-import org.springframework.core.MethodParameter;
 import org.springframework.shell.CompletionContext;
 import org.springframework.shell.CompletionProposal;
 import org.springframework.shell.command.CommandCatalog;
@@ -28,8 +27,9 @@ import org.springframework.shell.command.CommandCatalog;
  * A {@link ValueProvider} that can be used to auto-complete names of shell commands.
  *
  * @author Eric Bottard
+ * @author Janne Valkealahti
  */
-public class CommandValueProvider extends ValueProviderSupport {
+public class CommandValueProvider implements ValueProvider {
 
 	private final CommandCatalog commandRegistry;
 
@@ -38,7 +38,7 @@ public class CommandValueProvider extends ValueProviderSupport {
 	}
 
 	@Override
-	public List<CompletionProposal> complete(MethodParameter parameter, CompletionContext completionContext, String[] hints) {
+	public List<CompletionProposal> complete(CompletionContext completionContext) {
 		return commandRegistry.getRegistrations().keySet().stream()
 			.map(CompletionProposal::new)
 			.collect(Collectors.toList());

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

@@ -1,5 +1,5 @@
 /*
- * Copyright 2016 the original author or authors.
+ * Copyright 2016-2022 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.
@@ -19,9 +19,10 @@ package org.springframework.shell.standard;
 import java.util.ArrayList;
 import java.util.List;
 
-import org.springframework.core.MethodParameter;
+import org.springframework.core.ResolvableType;
 import org.springframework.shell.CompletionContext;
 import org.springframework.shell.CompletionProposal;
+import org.springframework.shell.command.CommandOption;
 
 /**
  * A {@link ValueProvider} that knows how to complete values for {@link Enum} typed parameters.
@@ -30,21 +31,28 @@ import org.springframework.shell.CompletionProposal;
 public class EnumValueProvider implements ValueProvider {
 
 	@Override
-	public boolean supports(MethodParameter parameter, CompletionContext completionContext) {
-		return Enum.class.isAssignableFrom(parameter.getParameterType());
-	}
-
-	@Override
-	public List<CompletionProposal> complete(MethodParameter parameter, CompletionContext completionContext, String[] hints) {
+	public List<CompletionProposal> complete(CompletionContext completionContext) {
 		List<CompletionProposal> result = new ArrayList<>();
-		for (Object v : parameter.getParameterType().getEnumConstants()) {
-			Enum<?> e = (Enum<?>) v;
-			String prefix = completionContext.currentWordUpToCursor();
-			if (prefix == null) {
-				prefix = "";
-			}
-			if (e.name().startsWith(prefix)) {
-				result.add(new CompletionProposal(e.name()));
+		CommandOption commandOption = completionContext.getCommandOption();
+		if (commandOption != null) {
+			ResolvableType type = commandOption.getType();
+			if (type != null) {
+				Class<?> clazz = type.getRawClass();
+				if (clazz != null) {
+					Object[] enumConstants = clazz.getEnumConstants();
+					if (enumConstants != null) {
+						for (Object v : enumConstants) {
+							Enum<?> e = (Enum<?>) v;
+							String prefix = completionContext.currentWordUpToCursor();
+							if (prefix == null) {
+								prefix = "";
+							}
+							if (e.name().startsWith(prefix)) {
+								result.add(new CompletionProposal(e.name()));
+							}
+						}
+					}
+				}
 			}
 		}
 		return result;

spring-shell-standard/src/main/java/org/springframework/shell/standard/FileValueProvider.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2017 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.
@@ -25,7 +25,6 @@ import java.nio.file.Paths;
 import java.util.List;
 import java.util.stream.Collectors;
 
-import org.springframework.core.MethodParameter;
 import org.springframework.shell.CompletionContext;
 import org.springframework.shell.CompletionProposal;
 
@@ -36,29 +35,25 @@ import static java.nio.file.FileVisitOption.FOLLOW_LINKS;
  * current working directory.
  *
  * @author Eric Bottard
+ * @author Janne Valkealahti
  */
 public class FileValueProvider implements ValueProvider {
-    @Override
-    public boolean supports(MethodParameter parameter, CompletionContext completionContext) {
-        return parameter.getParameterType().equals(File.class);
-    }
-
-    @Override
-    public List<CompletionProposal> complete(MethodParameter parameter, CompletionContext completionContext, String[] hints) {
 
+	@Override
+	public List<CompletionProposal> complete(CompletionContext completionContext) {
         String input = completionContext.currentWordUpToCursor();
         int lastSlash = input.lastIndexOf(File.separatorChar);
         Path dir = lastSlash > -1 ? Paths.get(input.substring(0, lastSlash+1)) : Paths.get("");
         String prefix = input.substring(lastSlash + 1, input.length());
 
         try {
-            return Files.find(dir, 1, (p, a) -> p.getFileName() != null && p.getFileName().toString().startsWith(prefix), FOLLOW_LINKS)
+            return Files
+                    .find(dir, 1, (p, a) -> p.getFileName() != null && p.getFileName().toString().startsWith(prefix),
+                            FOLLOW_LINKS)
                     .map(p -> new CompletionProposal(p.toString()))
                     .collect(Collectors.toList());
         } catch (IOException e) {
             throw new UncheckedIOException(e);
         }
-
-    }
-
+	}
 }

spring-shell-standard/src/main/java/org/springframework/shell/standard/StandardMethodTargetRegistrar.java

@@ -23,6 +23,7 @@ import java.util.HashMap;
 import java.util.List;
 import java.util.Map;
 import java.util.Set;
+import java.util.function.Function;
 import java.util.function.Supplier;
 import java.util.stream.Collectors;
 
@@ -36,13 +37,17 @@ import org.springframework.core.MethodParameter;
 import org.springframework.core.annotation.AnnotationUtils;
 import org.springframework.messaging.handler.invocation.InvocableHandlerMethod;
 import org.springframework.shell.Availability;
+import org.springframework.shell.CompletionContext;
+import org.springframework.shell.CompletionProposal;
 import org.springframework.shell.MethodTargetRegistrar;
 import org.springframework.shell.Utils;
 import org.springframework.shell.command.CommandCatalog;
 import org.springframework.shell.command.CommandRegistration;
 import org.springframework.shell.command.CommandRegistration.Builder;
 import org.springframework.shell.command.CommandRegistration.OptionSpec;
+import org.springframework.shell.standard.ShellOption.NoValueProvider;
 import org.springframework.util.Assert;
+import org.springframework.util.ClassUtils;
 import org.springframework.util.ObjectUtils;
 import org.springframework.util.ReflectionUtils;
 import org.springframework.util.StringUtils;
@@ -143,6 +148,14 @@ public class StandardMethodTargetRegistrar implements MethodTargetRegistrar, App
 							if (ObjectUtils.nullSafeEquals(so.defaultValue(), ShellOption.NONE)) {
 								optionSpec.required();
 							}
+							if (!ClassUtils.isAssignable(NoValueProvider.class, so.valueProvider())) {
+								Function<CompletionContext, List<CompletionProposal>> completionFunction = ctx -> {
+									ValueProvider valueProviderBean = this.applicationContext.getBean(so.valueProvider());
+									List<CompletionProposal> complete = valueProviderBean.complete(ctx);
+									return complete;
+								};
+								optionSpec.completion(completionFunction);
+							}
 						}
 					}
 					else {

spring-shell-standard/src/main/java/org/springframework/shell/standard/ValueProvider.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2016 the original author or authors.
+ * Copyright 2016-2022 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.
@@ -13,23 +13,27 @@
  * See the License for the specific language governing permissions and
  * limitations under the License.
  */
-
 package org.springframework.shell.standard;
 
 import java.util.List;
 
-import org.springframework.core.MethodParameter;
 import org.springframework.shell.CompletionContext;
 import org.springframework.shell.CompletionProposal;
 
 /**
- * Beans implementing this interface are queried during TAB completion to gather possible values of a parameter.
+ * Beans implementing this interface are queried during TAB completion to gather
+ * possible values of a parameter.
  *
  * @author Eric Bottard
+ * @author Janne Valkealahti
  */
 public interface ValueProvider {
 
-	boolean supports(MethodParameter parameter, CompletionContext completionContext);
-
-	List<CompletionProposal> complete(MethodParameter parameter, CompletionContext completionContext, String[] hints);
+	/**
+	 * Complete completion proposals.
+	 *
+	 * @param completionContext the context
+	 * @return the completion proposals
+	 */
+	List<CompletionProposal> complete(CompletionContext completionContext);
 }

spring-shell-standard/src/main/java/org/springframework/shell/standard/ValueProviderSupport.java

@@ -1,38 +0,0 @@
-/*
- * Copyright 2016 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.standard;
-
-import org.springframework.core.MethodParameter;
-import org.springframework.shell.CompletionContext;
-
-/**
- * Base class for {@link ValueProvider} that match by type. Subclasses {@literal C} will be selected for parameters
- * whose {@literal @}{@link ShellOption#valueProvider()} return the concrete class {@literal C}.
- *
- * @author Eric Bottard
- */
-public abstract class ValueProviderSupport implements ValueProvider {
-
-	@Override
-	public boolean supports(MethodParameter parameter, CompletionContext completionContext) {
-		ShellOption annotation = parameter.getParameterAnnotation(ShellOption.class);
-		if (annotation == null) {
-			return false;
-		}
-		return annotation.valueProvider().isAssignableFrom(this.getClass());
-	}
-}

spring-shell-standard/src/test/java/org/springframework/shell/standard/CommandValueProviderTests.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2017 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.
@@ -13,11 +13,8 @@
  * See the License for the specific language governing permissions and
  * limitations under the License.
  */
-
 package org.springframework.shell.standard;
 
-
-import java.lang.reflect.Method;
 import java.util.Arrays;
 import java.util.HashMap;
 import java.util.List;
@@ -28,13 +25,10 @@ import org.junit.jupiter.api.Test;
 import org.mockito.Mock;
 import org.mockito.MockitoAnnotations;
 
-import org.springframework.core.MethodParameter;
 import org.springframework.shell.CompletionContext;
 import org.springframework.shell.CompletionProposal;
-import org.springframework.shell.Utils;
 import org.springframework.shell.command.CommandCatalog;
 import org.springframework.shell.command.CommandRegistration;
-import org.springframework.util.ReflectionUtils;
 
 import static org.assertj.core.api.Assertions.assertThat;
 import static org.mockito.Mockito.when;
@@ -44,7 +38,7 @@ import static org.mockito.Mockito.when;
  *
  * @author Eric Bottard
  */
-public class CommandValueProviderTest {
+public class CommandValueProviderTests {
 
 	@Mock
 	private CommandCatalog catalog;
@@ -58,30 +52,17 @@ public class CommandValueProviderTest {
 	public void testValues() {
 		CommandValueProvider valueProvider = new CommandValueProvider(catalog);
 
-		Method help = ReflectionUtils.findMethod(Command.class, "help", String.class);
-		MethodParameter methodParameter = Utils.createMethodParameter(help, 0);
-		CompletionContext completionContext = new CompletionContext(Arrays.asList("help", "m"), 0, 0);
-		boolean supports = valueProvider.supports(methodParameter, completionContext);
+		CompletionContext completionContext = new CompletionContext(Arrays.asList("help", "m"), 0, 0, null, null);
 
-		assertThat(supports).isEqualTo(true);
 		Map<String, CommandRegistration> registrations = new HashMap<>();
 		registrations.put("me", null);
 		registrations.put("meow", null);
 		registrations.put("yourself", null);
 
 		when(catalog.getRegistrations()).thenReturn(registrations);
-		List<CompletionProposal> proposals = valueProvider.complete(methodParameter, completionContext, new String[0]);
+		List<CompletionProposal> proposals = valueProvider.complete(completionContext);
 
 		assertThat(proposals).extracting("value", String.class)
 			.contains("me", "meow", "yourself");
 	}
-
-
-	public static class Command {
-
-		public void help(@ShellOption(valueProvider = CommandValueProvider.class) String command) {
-
-		}
-	}
-
 }

spring-shell-standard/src/test/java/org/springframework/shell/standard/Remote.java

@@ -1,91 +0,0 @@
-/*
- * Copyright 2015 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.standard;
-
-import java.util.List;
-import java.util.stream.Collectors;
-import java.util.stream.Stream;
-
-import org.springframework.core.MethodParameter;
-import org.springframework.shell.CompletionContext;
-import org.springframework.shell.CompletionProposal;
-
-/**
- * An example commands class.
- *
- * @author Eric Bottard
- * @author Florent Biville
- */
-public class Remote {
-
-	/**
-	 * A command method that showcases<ul>
-	 *     <li>default handling for booleans (force)</li>
-	 *     <li>default parameter name discovery (name)</li>
-	 *     <li>default value supplying (foo and bar)</li>
-	 * </ul>
-	 */
-	@ShellMethod(value = "switch channels")
-	public void zap(boolean force,
-	                String name,
-	                @ShellOption(defaultValue="defoolt") String foo,
-	                @ShellOption(value = {"--bar", "--baz"}, defaultValue = "last") String bar) {
-	}
-
-	@ShellMethod(value = "bye bye")
-	public void shutdown(@ShellOption Delay delay) {
-
-	}
-	
-	@ShellMethod(value = "a different prefix", prefix = "-")
-	public void prefixTest(@ShellOption String message) {
-
-	}
-
-	@ShellMethod(value = "add 3 numbers together")
-	public void add(@ShellOption(arity = 3, valueProvider = NumberValueProvider.class) List<Integer> numbers) {
-
-	}
-
-	@ShellMethod(value = "add 3 numbers together (array)")
-	public void addAsArray(@ShellOption(arity = 3, valueProvider = NumberValueProvider.class) int[] numbers) {
-
-	}
-
-	public enum Delay {
-		small, medium, big;
-	}
-
-
-	public static class NumberValueProvider extends ValueProviderSupport {
-
-		private final String[] values;
-
-		public NumberValueProvider(String... values) {
-			this.values = values;
-		}
-
-		@Override
-		public List<CompletionProposal> complete(MethodParameter parameter, CompletionContext completionContext, String[] hints) {
-			String prefix = completionContext.currentWord() != null ? completionContext.currentWord() : "";
-			return Stream.of(values)
-					.filter(n -> n.startsWith(prefix))
-					.map(CompletionProposal::new)
-					.collect(Collectors.toList());
-		}
-	}
-}