Component text can be truncated

- BaseComponentContext has new field terminalWidth.
- StringToStyleExpressionRenderer contains new format
  for "truncate-" prefixes and this is something
  what template can use to instruct max length based
  on terminal width.
- Change single/multi selectors to use this feature.
- Fixes #543

spring-shell-core/src/main/java/org/springframework/shell/component/MultiItemSelector.java

@@ -59,6 +59,7 @@ public class MultiItemSelector<T, I extends Nameable & Matchable & Enableable &
 		}
 		currentContext = MultiItemSelectorContext.empty(getItemMapper());
 		currentContext.setName(name);
+		currentContext.setTerminalWidth(getTerminal().getWidth());
 		if (currentContext.getItems() == null) {
 			currentContext.setItems(getItems());
 		}

spring-shell-core/src/main/java/org/springframework/shell/component/SingleItemSelector.java

@@ -59,6 +59,7 @@ public class SingleItemSelector<T, I extends Nameable & Matchable & Enableable &
 		}
 		currentContext = SingleItemSelectorContext.empty(getItemMapper());
 		currentContext.setName(name);
+		currentContext.setTerminalWidth(getTerminal().getWidth());
 		if (currentContext.getItems() == null) {
 			currentContext.setItems(getItems());
 		}

spring-shell-core/src/main/java/org/springframework/shell/component/context/BaseComponentContext.java

@@ -30,6 +30,8 @@ import java.util.stream.Stream;
 public class BaseComponentContext<C extends ComponentContext<C>> extends LinkedHashMap<Object, Object>
 		implements ComponentContext<C> {
 
+	private Integer terminalWidth;
+
 	@Override
 	public Object get(Object key) {
 		Object o = super.get(key);
@@ -60,12 +62,28 @@ public class BaseComponentContext<C extends ComponentContext<C>> extends LinkedH
 		return entrySet().stream();
 	}
 
+	@Override
+	public Integer getTerminalWidth() {
+		return terminalWidth;
+	}
+
+	@Override
+	public void setTerminalWidth(Integer terminalWidth) {
+		this.terminalWidth = terminalWidth;
+	}
+
 	@Override
 	public Map<String, Object> toTemplateModel() {
 		Map<String, Object> attributes = new HashMap<>();
 		// hardcoding enclosed map values into 'rawValues'
 		// as it may contain anything
 		attributes.put("rawValues", this);
+		attributes.put("terminalWidth", terminalWidth);
 		return attributes;
 	}
+
+	@Override
+	public String toString() {
+		return "BaseComponentContext [terminalWidth=" + terminalWidth + "]";
+	}
 }

spring-shell-core/src/main/java/org/springframework/shell/component/context/ComponentContext.java

@@ -80,6 +80,20 @@ public interface ComponentContext<C extends ComponentContext<C>> {
 	 */
 	Stream<Map.Entry<Object, Object>> stream();
 
+	/**
+	 * Get terminal width.
+	 *
+	 * @return a terminal width
+	 */
+	Integer getTerminalWidth();
+
+	/**
+	 * Set terminal width.
+	 *
+	 * @param terminalWidth the width
+	 */
+	void setTerminalWidth(Integer terminalWidth);
+
 	/**
 	 * Gets context values as a map. Every context implementation can
 	 * do their own model as essentially what matter is a one coming

spring-shell-core/src/main/java/org/springframework/shell/style/StringToStyleExpressionRenderer.java

@@ -16,6 +16,7 @@
 package org.springframework.shell.style;
 
 import java.util.Locale;
+import java.util.stream.Stream;
 
 import org.jline.style.StyleExpression;
 import org.stringtemplate.v4.AttributeRenderer;
@@ -33,6 +34,7 @@ import org.springframework.util.StringUtils;
 public class StringToStyleExpressionRenderer implements AttributeRenderer<String> {
 
 	private final ThemeResolver themeResolver;
+	private final static String TRUNCATE = "truncate-";
 
 	public StringToStyleExpressionRenderer(ThemeResolver themeResolver) {
 		Assert.notNull(themeResolver, "themeResolver must be set");
@@ -44,8 +46,51 @@ public class StringToStyleExpressionRenderer implements AttributeRenderer<String
 		if (!StringUtils.hasText(formatString)) {
 			return value;
 		}
-		else {
+		else if (formatString.startsWith("style-")) {
 			return String.format("@{%s %s}", themeResolver.resolveStyleTag(formatString), value);
 		}
+		else if (formatString.startsWith(TRUNCATE)) {
+			String f = formatString.substring(TRUNCATE.length());
+			TruncateValues config = mapValues(f);
+			if (value.length() + config.prefix > config.width) {
+				return String.format(locale, "%1." + (config.width - config.prefix - 2) + "s.." , value);
+			}
+			else {
+				return value;
+			}
+		}
+		else {
+			return String.format(locale, formatString, value);
+		}
+	}
+
+	private static class TruncateValues {
+		Integer width;
+		Integer prefix;
+
+		public void setWidth(Integer width) {
+			this.width = width;
+		}
+		public void setPrefix(Integer prefix) {
+			this.prefix = prefix;
+		}
+	}
+
+	private static TruncateValues mapValues(String expression) {
+		TruncateValues values = new TruncateValues();
+		Stream.of(expression.split("-"))
+			.map(String::trim)
+			.forEach(v -> {
+				String[] split = v.split(":", 2);
+				if (split.length == 2) {
+					if ("width".equals(split[0])) {
+						values.setWidth(Integer.parseInt(split[1]));
+					}
+					else if ("prefix".equals(split[0])) {
+						values.setPrefix(Integer.parseInt(split[1]));
+					}
+				}
+			});
+		return values;
 	}
 }

spring-shell-core/src/main/resources/org/springframework/shell/component/multi-item-selector-default.stg

@@ -1,10 +1,15 @@
+// selector rows
+truncate(name,model) ::= <%
+<name; format={truncate-width:<model.terminalWidth>-prefix:5}>
+%>
+
 // used to select style if item is selected/unselected
 selected_style(flag) ::= <%
 <if(flag)>style-item-selected<else>style-item-unselected<endif>
 %>
 
 // selector rows
-select_item(item) ::= <%
+select_item(item,model) ::= <%
 <if(item.onrow)>
   <({<figures.rightPointingQuotation> }); format="style-item-selector">
 <else>
@@ -13,16 +18,16 @@ select_item(item) ::= <%
 
 <if(item.enabled)>
   <if(item.selected)>
-    <({<figures.checkboxOn> }); format=selected_style(item.selected)> <item.name>
+    <({<figures.checkboxOn> }); format=selected_style(item.selected)> <truncate(item.name,model)>
   <else>
-    <({<figures.checkboxOff> }); format=selected_style(item.selected)> <item.name>
+    <({<figures.checkboxOff> }); format=selected_style(item.selected)> <truncate(item.name,model)>
   <endif>
 <else>
   <if(item.selected)>
-     <({<figures.checkboxOn> }); format="style-item-disabled"> <item.name; format="style-item-disabled">
+     <({<figures.checkboxOn> }); format="style-item-disabled"> <({<truncate(item.name,model)>}); format="style-item-disabled">
   <else>
-    <({<figures.checkboxOff> }); format="style-item-disabled"> <item.name; format="style-item-disabled">
+    <({<figures.checkboxOff> }); format="style-item-disabled"> <({<truncate(item.name,model)>}); format="style-item-disabled">
-  <endif>  
+  <endif>
 <endif>
 %>
 
@@ -58,7 +63,7 @@ result(model) ::= <<
 // component is running
 running(model) ::= <<
 <question_name(model)> <info(model)>
-<model.rows:{x|<select_item(x)>}; separator="\n">
+<model.rows:{x|<select_item(x,model)>}; separator="\n">
 >>
 
 // main - hardcoded name

spring-shell-core/src/main/resources/org/springframework/shell/component/single-item-selector-default.stg

@@ -1,9 +1,13 @@
 // selector rows
-select_item(item) ::= <%
+truncate(name,model) ::= <%
+<name; format={truncate-width:<model.terminalWidth>-prefix:2}>
+%>
+
+select_item(item,model) ::= <%
 <if(item.selected)>
-<({<figures.rightPointingQuotation> }); format="style-item-selector"><item.name; format="style-item-selector">
+<({<figures.rightPointingQuotation> }); format="style-item-selector"><({<truncate(item.name,model)>}); format="style-item-selector">
 <else>
-<("  ")><item.name>
+<("  ")><truncate(item.name,model)>
 <endif>
 %>
 
@@ -34,7 +38,7 @@ result(model) ::= <<
 // component is running
 running(model) ::= <<
 <question_name(model)> <info(model)>
-<model.rows:{x|<select_item(x)>}; separator="\n">
+<model.rows:{x|<select_item(x,model)>}; separator="\n">
 >>
 
 // main - hardcoded name

spring-shell-core/src/test/java/org/springframework/shell/component/AbstractShellTests.java

@@ -80,7 +80,7 @@ public abstract class AbstractShellTests {
 
         pipedInputStream.connect(pipedOutputStream);
 		terminal = new DumbTerminal("terminal", "ansi", pipedInputStream, consoleOut, StandardCharsets.UTF_8);
-        terminal.setSize(new Size(1, 1));
+        terminal.setSize(new Size(80, 24));
 
         executorService.execute(() -> {
             try {

spring-shell-core/src/test/java/org/springframework/shell/style/StringToStyleExpressionRendererTests.java

@@ -0,0 +1,71 @@
+/*
+ * 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.style;
+
+import java.util.Locale;
+import java.util.stream.Stream;
+
+import org.junit.jupiter.api.BeforeAll;
+import org.junit.jupiter.api.Test;
+import org.junit.jupiter.params.ParameterizedTest;
+import org.junit.jupiter.params.provider.Arguments;
+import org.junit.jupiter.params.provider.MethodSource;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+class StringToStyleExpressionRendererTests {
+
+	private static Locale LOCALE = Locale.getDefault();
+	private static StringToStyleExpressionRenderer renderer;
+
+	@BeforeAll
+	static void setup() {
+		ThemeRegistry themeRegistry = new ThemeRegistry();
+		themeRegistry.register(new Theme() {
+			@Override
+			public String getName() {
+				return "default";
+			}
+
+			@Override
+			public ThemeSettings getSettings() {
+				return ThemeSettings.defaults();
+			}
+		});
+		ThemeResolver themeResolver = new ThemeResolver(themeRegistry, "default");
+		renderer = new StringToStyleExpressionRenderer(themeResolver);
+	}
+
+	@Test
+	void emptyFormatReturnsValue() {
+		String value = renderer.toString("fake", null, LOCALE);
+		assertThat(value).isEqualTo("fake");
+	}
+
+	static Stream<Arguments> truncate() {
+		return Stream.of(
+			Arguments.of("0123456789", "truncate-width:6-prefix:2", "01.."),
+			Arguments.of("0123456789", "truncate-width:6-prefix:0", "0123.."),
+			Arguments.of("0123456789", "truncate-width:11-prefix:0", "0123456789")
+		);
+	}
+
+	@ParameterizedTest
+	@MethodSource
+	void truncate(String value, String expression, String expected) {
+		assertThat(renderer.toString(value, expression, LOCALE)).isEqualTo(expected);
+	}
+}

spring-shell-docs/src/main/asciidoc/using-shell-components-ui-render.adoc

@@ -89,3 +89,14 @@ from a parent component types. The following tables show those context variables
 |The current cursor row in a selector.
 
 |===
+
+
+[[componentcontext-template-variables]]
+.ComponentContext Template Variables
+|===
+|Key |Description
+
+|`terminalWidth`
+|The width of terminal, type is _Integer_ and defaults to _NULL_ if not set.
+
+|===

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

@@ -39,6 +39,7 @@ import org.springframework.shell.component.support.SelectorItem;
 import org.springframework.shell.standard.AbstractShellComponent;
 import org.springframework.shell.standard.ShellComponent;
 import org.springframework.shell.standard.ShellMethod;
+import org.springframework.shell.standard.ShellOption;
 import org.springframework.util.StringUtils;
 
 @ShellComponent
@@ -75,10 +76,16 @@ public class ComponentCommands extends AbstractShellComponent {
 	}
 
 	@ShellMethod(key = "component single", value = "Single selector", group = "Components")
-	public String singleSelector() {
+	public String singleSelector(
+		@ShellOption(defaultValue = ShellOption.NULL) Boolean longKeys
+	) {
 		List<SelectorItem<String>> items = new ArrayList<>();
 		items.add(SelectorItem.of("key1", "value1"));
 		items.add(SelectorItem.of("key2", "value2"));
+		if (longKeys != null && longKeys == true) {
+			items.add(SelectorItem.of("key3 long long long long long", "value3"));
+			items.add(SelectorItem.of("key4 long long long long long long long long long long", "value4"));
+		}
 		SingleItemSelector<String, SelectorItem<String>> component = new SingleItemSelector<>(getTerminal(),
 				items, "testSimple", null);
 		component.setResourceLoader(getResourceLoader());
@@ -90,11 +97,17 @@ public class ComponentCommands extends AbstractShellComponent {
 	}
 
 	@ShellMethod(key = "component multi", value = "Multi selector", group = "Components")
-	public String multiSelector() {
+	public String multiSelector(
+		@ShellOption(defaultValue = ShellOption.NULL) Boolean longKeys
+	) {
 		List<SelectorItem<String>> items = new ArrayList<>();
 		items.add(SelectorItem.of("key1", "value1"));
 		items.add(SelectorItem.of("key2", "value2", false, true));
 		items.add(SelectorItem.of("key3", "value3"));
+		if (longKeys != null && longKeys == true) {
+			items.add(SelectorItem.of("key4 long long long long long", "value4", false, true));
+			items.add(SelectorItem.of("key5 long long long long long long long long long long", "value5"));
+		}
 		MultiItemSelector<String, SelectorItem<String>> component = new MultiItemSelector<>(getTerminal(),
 				items, "testSimple", null);
 		component.setResourceLoader(getResourceLoader());