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-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
+	}
+}