Add script command.

Also: prepare for execute-then-quit.
Add javadocs

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

@@ -32,7 +32,6 @@ import org.springframework.stereotype.Component;
  *
  * @author Eric Bottard
  */
-@Component
 public class CommandValueProvider extends ValueProviderSupport {
 
 	private final CommandRegistry commandRegistry;

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

@@ -28,7 +28,6 @@ import org.springframework.stereotype.Component;
  * A {@link ValueProvider} that knows how to complete values for {@link Enum} typed parameters.
  * @author Eric Bottard
  */
-@Component
 public class EnumValueProvider implements ValueProvider {
 
 	@Override

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

@@ -0,0 +1,65 @@
+/*
+ * Copyright 2017 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
+ *
+ *      http://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;
+import org.springframework.shell.CompletionProposal;
+
+import java.io.File;
+import java.io.IOException;
+import java.io.UncheckedIOException;
+import java.nio.file.FileVisitOption;
+import java.nio.file.Files;
+import java.nio.file.Path;
+import java.nio.file.Paths;
+import java.util.List;
+import java.util.stream.Collectors;
+
+import static java.nio.file.FileVisitOption.FOLLOW_LINKS;
+
+/**
+ * A {@link ValueProvider} that can populate names of local {@link File}s, either absolute or relative to the
+ * current working directory.
+ *
+ * @author Eric Bottard
+ */
+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) {
+
+        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)
+                    .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/StandardAPIAutoConfiguration.java

@@ -41,6 +41,11 @@ public class StandardAPIAutoConfiguration {
 		return new EnumValueProvider();
 	}
 
+	@Bean
+	public ValueProvider fileValueProvider() {
+		return new FileValueProvider();
+	}
+
 	@Bean
 	public MethodTargetRegistrar standardMethodTargetResolver() {
 		return new StandardMethodTargetRegistrar();

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

@@ -23,6 +23,9 @@ 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.
+ *
+ * @author Eric Bottard
  */
 public interface ValueProvider {