Introduce BuiltinFeatures

src/main/java/com/hubspot/jinjava/LegacyOverrides.java

@@ -146,6 +146,10 @@ public Builder withUseSnakeCasePropertyNaming(boolean useSnakeCasePropertyNaming
       return this;
     }
 
+    /**
+     * Use {@link com.hubspot.jinjava.features.BuiltInFeatures#WHITESPACE_REQUIRED_WITHIN_TOKENS} instead
+     */
+    @Deprecated
     public Builder withWhitespaceRequiredWithinTokens(
       boolean whitespaceRequiredWithinTokens
     ) {

src/main/java/com/hubspot/jinjava/features/BuiltInFeatures.java

@@ -0,0 +1,11 @@
+package com.hubspot.jinjava.features;
+
+public interface BuiltInFeatures {
+  String WHITESPACE_REQUIRED_WITHIN_TOKENS = "whitespace_required_within_tokens";
+  String FIXED_DATE_TIME_FILTER_NULL_ARG = "FIXED_DATE_TIME_FILTER_NULL_ARG";
+  String ECHO_UNDEFINED = "echoUndefined";
+  String PREVENT_ACCIDENTAL_EXPRESSIONS = "PREVENT_ACCIDENTAL_EXPRESSIONS";
+  String IGNORE_NESTED_INTERPRETATION_PARSE_ERRORS =
+    "IGNORE_NESTED_INTERPRETATION_PARSE_ERRORS";
+  String OUTPUT_UNDEFINED_VARIABLES_ERROR = "OUTPUT_UNDEFINED_VARIABLES_ERROR";
+}

src/main/java/com/hubspot/jinjava/features/DateTimeFeatureActivationStrategy.java

@@ -20,6 +20,11 @@ public boolean isActive(Context context) {
     return ZonedDateTime.now().isAfter(activateAt);
   }
 
+  @Override
+  public boolean isActive() {
+    return false; // Not usable without context
+  }
+
   public ZonedDateTime getActivateAt() {
     return activateAt;
   }

src/main/java/com/hubspot/jinjava/features/FeatureActivationStrategy.java

@@ -3,5 +3,9 @@
 import com.hubspot.jinjava.interpret.Context;
 
 public interface FeatureActivationStrategy {
-  boolean isActive(Context context);
+  default boolean isActive(Context context) {
+    return isActive();
+  }
+
+  boolean isActive();
 }

src/main/java/com/hubspot/jinjava/features/FeatureConfig.java

@@ -1,8 +1,10 @@
 package com.hubspot.jinjava.features;
 
 import com.google.common.collect.ImmutableMap;
+import com.hubspot.jinjava.interpret.Context;
 import java.util.HashMap;
 import java.util.Map;
+import java.util.function.Function;
 
 public class FeatureConfig {
 
@@ -24,6 +26,25 @@ public static class Builder {
 
     private final Map<String, FeatureActivationStrategy> features = new HashMap<>();
 
+    @Deprecated
+    public Builder add(String name, Function<Context, Boolean> strategyFunction) {
+      features.put(
+        name,
+        new FeatureActivationStrategy() {
+          @Override
+          public boolean isActive(Context context) {
+            return strategyFunction.apply(context);
+          }
+
+          @Override
+          public boolean isActive() {
+            return false;
+          }
+        }
+      );
+      return this;
+    }
+
     public Builder add(String name, FeatureActivationStrategy strategy) {
       features.put(name, strategy);
       return this;

src/main/java/com/hubspot/jinjava/features/FeatureStrategies.java

@@ -2,6 +2,6 @@
 
 public class FeatureStrategies {
 
-  public static final FeatureActivationStrategy INACTIVE = c -> false;
-  public static final FeatureActivationStrategy ACTIVE = c -> true;
+  public static final FeatureActivationStrategy INACTIVE = () -> false;
+  public static final FeatureActivationStrategy ACTIVE = () -> true;
 }

src/main/java/com/hubspot/jinjava/features/Features.java

@@ -14,6 +14,10 @@ public boolean isActive(String featureName, Context context) {
     return getActivationStrategy(featureName).isActive(context);
   }
 
+  public boolean isActive(String featureName) {
+    return getActivationStrategy(featureName).isActive();
+  }
+
   public FeatureActivationStrategy getActivationStrategy(String featureName) {
     return featureConfig.getFeature(featureName);
   }

src/main/java/com/hubspot/jinjava/interpret/JinjavaInterpreter.java

@@ -30,6 +30,7 @@
 import com.hubspot.jinjava.el.ExpressionResolver;
 import com.hubspot.jinjava.el.ext.DeferredParsingException;
 import com.hubspot.jinjava.el.ext.ExtendedParser;
+import com.hubspot.jinjava.features.BuiltInFeatures;
 import com.hubspot.jinjava.interpret.AutoCloseableSupplier.AutoCloseableImpl;
 import com.hubspot.jinjava.interpret.Context.TemporaryValueClosable;
 import com.hubspot.jinjava.interpret.ContextConfigurationIF.ErrorHandlingStrategyIF;
@@ -87,9 +88,9 @@ public class JinjavaInterpreter implements PyishSerializable {
     "ignored_output_from_extends";
 
   public static final String OUTPUT_UNDEFINED_VARIABLES_ERROR =
-    "OUTPUT_UNDEFINED_VARIABLES_ERROR";
+    BuiltInFeatures.OUTPUT_UNDEFINED_VARIABLES_ERROR;
   public static final String IGNORE_NESTED_INTERPRETATION_PARSE_ERRORS =
-    "IGNORE_NESTED_INTERPRETATION_PARSE_ERRORS";
+    BuiltInFeatures.IGNORE_NESTED_INTERPRETATION_PARSE_ERRORS;
   private final Multimap<String, BlockInfo> blocks = ArrayListMultimap.create();
   private final LinkedList<Node> extendParentRoots = new LinkedList<>();
   private final Map<String, RevertibleObject> revertibleObjects = new HashMap<>();
@@ -288,9 +289,7 @@ public String renderFlat(String template, long renderLimit) {
   private TemporaryValueClosable<ErrorHandlingStrategy> ignoreParseErrorsIfActivated() {
     return config
         .getFeatures()
-        .getActivationStrategy(
-          JinjavaInterpreter.IGNORE_NESTED_INTERPRETATION_PARSE_ERRORS
-        )
+        .getActivationStrategy(BuiltInFeatures.IGNORE_NESTED_INTERPRETATION_PARSE_ERRORS)
         .isActive(context)
       ? context.withErrorHandlingStrategy(ErrorHandlingStrategyIF.ignoreAll())
       : TemporaryValueClosable.noOp();
@@ -664,7 +663,7 @@ public Object retraceVariable(String variable, int lineNumber, int startPosition
       if (
         getConfig()
           .getFeatures()
-          .getActivationStrategy(OUTPUT_UNDEFINED_VARIABLES_ERROR)
+          .getActivationStrategy(BuiltInFeatures.OUTPUT_UNDEFINED_VARIABLES_ERROR)
           .isActive(context)
       ) {
         addError(

src/main/java/com/hubspot/jinjava/lib/expression/DefaultExpressionStrategy.java

@@ -1,5 +1,6 @@
 package com.hubspot.jinjava.lib.expression;
 
+import com.hubspot.jinjava.features.BuiltInFeatures;
 import com.hubspot.jinjava.features.FeatureActivationStrategy;
 import com.hubspot.jinjava.interpret.JinjavaInterpreter;
 import com.hubspot.jinjava.lib.filter.EscapeFilter;
@@ -12,7 +13,7 @@
 public class DefaultExpressionStrategy implements ExpressionStrategy {
 
   private static final long serialVersionUID = 436239440273704843L;
-  public static final String ECHO_UNDEFINED = "echoUndefined";
+  public static final String ECHO_UNDEFINED = BuiltInFeatures.ECHO_UNDEFINED;
 
   public RenderedOutputNode interpretOutput(
     ExpressionToken master,
@@ -26,7 +27,7 @@ public RenderedOutputNode interpretOutput(
     final FeatureActivationStrategy feat = interpreter
       .getConfig()
       .getFeatures()
-      .getActivationStrategy(ECHO_UNDEFINED);
+      .getActivationStrategy(BuiltInFeatures.ECHO_UNDEFINED);
 
     if (var == null && feat.isActive(interpreter.getContext())) {
       return new RenderedOutputNode(master.getImage());

src/main/java/com/hubspot/jinjava/lib/filter/BetweenTimesFilter.java

@@ -1,10 +1,9 @@
 package com.hubspot.jinjava.lib.filter;
 
-import static com.hubspot.jinjava.lib.filter.time.DateTimeFormatHelper.FIXED_DATE_TIME_FILTER_NULL_ARG;
-
 import com.hubspot.jinjava.doc.annotations.JinjavaDoc;
 import com.hubspot.jinjava.doc.annotations.JinjavaParam;
 import com.hubspot.jinjava.doc.annotations.JinjavaSnippet;
+import com.hubspot.jinjava.features.BuiltInFeatures;
 import com.hubspot.jinjava.features.DateTimeFeatureActivationStrategy;
 import com.hubspot.jinjava.features.FeatureActivationStrategy;
 import com.hubspot.jinjava.interpret.InvalidArgumentException;
@@ -91,7 +90,7 @@ private ZonedDateTime getZonedDateTime(Object var, String position) {
         FeatureActivationStrategy feat = interpreter
           .getConfig()
           .getFeatures()
-          .getActivationStrategy(FIXED_DATE_TIME_FILTER_NULL_ARG);
+          .getActivationStrategy(BuiltInFeatures.FIXED_DATE_TIME_FILTER_NULL_ARG);
 
         if (feat.isActive(interpreter.getContext())) {
           var = ((DateTimeFeatureActivationStrategy) feat).getActivateAt();

src/main/java/com/hubspot/jinjava/lib/filter/UnixTimestampFilter.java

@@ -1,10 +1,9 @@
 package com.hubspot.jinjava.lib.filter;
 
-import static com.hubspot.jinjava.lib.filter.time.DateTimeFormatHelper.FIXED_DATE_TIME_FILTER_NULL_ARG;
-
 import com.hubspot.jinjava.doc.annotations.JinjavaDoc;
 import com.hubspot.jinjava.doc.annotations.JinjavaParam;
 import com.hubspot.jinjava.doc.annotations.JinjavaSnippet;
+import com.hubspot.jinjava.features.BuiltInFeatures;
 import com.hubspot.jinjava.features.DateTimeFeatureActivationStrategy;
 import com.hubspot.jinjava.features.FeatureActivationStrategy;
 import com.hubspot.jinjava.interpret.InvalidArgumentException;
@@ -40,7 +39,7 @@ public Object filter(Object var, JinjavaInterpreter interpreter, String... args)
       FeatureActivationStrategy feat = interpreter
         .getConfig()
         .getFeatures()
-        .getActivationStrategy(FIXED_DATE_TIME_FILTER_NULL_ARG);
+        .getActivationStrategy(BuiltInFeatures.FIXED_DATE_TIME_FILTER_NULL_ARG);
 
       if (feat.isActive(interpreter.getContext())) {
         var = ((DateTimeFeatureActivationStrategy) feat).getActivateAt();

src/main/java/com/hubspot/jinjava/lib/filter/time/DateTimeFormatHelper.java

@@ -1,6 +1,7 @@
 package com.hubspot.jinjava.lib.filter.time;
 
 import com.hubspot.jinjava.JinjavaConfig;
+import com.hubspot.jinjava.features.BuiltInFeatures;
 import com.hubspot.jinjava.features.DateTimeFeatureActivationStrategy;
 import com.hubspot.jinjava.features.FeatureActivationStrategy;
 import com.hubspot.jinjava.interpret.InvalidArgumentException;
@@ -21,7 +22,7 @@
 public final class DateTimeFormatHelper {
 
   public static final String FIXED_DATE_TIME_FILTER_NULL_ARG =
-    "FIXED_DATE_TIME_FILTER_NULL_ARG";
+    BuiltInFeatures.FIXED_DATE_TIME_FILTER_NULL_ARG;
   private final String name;
   private final Function<FormatStyle, DateTimeFormatter> cannedFormatterFunction;
 
@@ -118,7 +119,7 @@ public Object checkForNullVar(Object var, String name) {
     FeatureActivationStrategy feat = interpreter
       .getConfig()
       .getFeatures()
-      .getActivationStrategy(FIXED_DATE_TIME_FILTER_NULL_ARG);
+      .getActivationStrategy(BuiltInFeatures.FIXED_DATE_TIME_FILTER_NULL_ARG);
 
     return feat.isActive(interpreter.getContext())
       ? ((DateTimeFeatureActivationStrategy) feat).getActivateAt()

src/main/java/com/hubspot/jinjava/lib/fn/Functions.java

@@ -1,13 +1,12 @@
 package com.hubspot.jinjava.lib.fn;
 
-import static com.hubspot.jinjava.lib.filter.time.DateTimeFormatHelper.FIXED_DATE_TIME_FILTER_NULL_ARG;
-
 import com.google.common.collect.Lists;
 import com.hubspot.jinjava.JinjavaConfig;
 import com.hubspot.jinjava.doc.annotations.JinjavaDoc;
 import com.hubspot.jinjava.doc.annotations.JinjavaParam;
 import com.hubspot.jinjava.doc.annotations.JinjavaSnippet;
 import com.hubspot.jinjava.el.ext.NamedParameter;
+import com.hubspot.jinjava.features.BuiltInFeatures;
 import com.hubspot.jinjava.features.DateTimeFeatureActivationStrategy;
 import com.hubspot.jinjava.features.FeatureActivationStrategy;
 import com.hubspot.jinjava.interpret.DeferredValueException;
@@ -229,7 +228,7 @@ public static String dateTimeFormat(Object var, String... format) {
       FeatureActivationStrategy feat = interpreter
         .getConfig()
         .getFeatures()
-        .getActivationStrategy(FIXED_DATE_TIME_FILTER_NULL_ARG);
+        .getActivationStrategy(BuiltInFeatures.FIXED_DATE_TIME_FILTER_NULL_ARG);
 
       if (feat.isActive(interpreter.getContext())) {
         var = ((DateTimeFeatureActivationStrategy) feat).getActivateAt();

src/main/java/com/hubspot/jinjava/tree/output/OutputList.java

@@ -1,5 +1,6 @@
 package com.hubspot.jinjava.tree.output;
 
+import com.hubspot.jinjava.features.BuiltInFeatures;
 import com.hubspot.jinjava.interpret.JinjavaInterpreter;
 import com.hubspot.jinjava.interpret.OutputTooBigException;
 import com.hubspot.jinjava.interpret.TemplateError;
@@ -11,7 +12,7 @@
 public class OutputList {
 
   public static final String PREVENT_ACCIDENTAL_EXPRESSIONS =
-    "PREVENT_ACCIDENTAL_EXPRESSIONS";
+    BuiltInFeatures.PREVENT_ACCIDENTAL_EXPRESSIONS;
   private final List<OutputNode> nodes = new LinkedList<>();
   private final List<BlockPlaceholderOutputNode> blocks = new LinkedList<>();
   private final long maxOutputSize;
@@ -58,7 +59,7 @@ public String getValue() {
       .filter(config ->
         config
           .getFeatures()
-          .getActivationStrategy(PREVENT_ACCIDENTAL_EXPRESSIONS)
+          .getActivationStrategy(BuiltInFeatures.PREVENT_ACCIDENTAL_EXPRESSIONS)
           .isActive(null)
       )
       .map(config ->

src/main/java/com/hubspot/jinjava/tree/parse/TokenScanner.java

@@ -19,6 +19,7 @@
 
 import com.google.common.collect.AbstractIterator;
 import com.hubspot.jinjava.JinjavaConfig;
+import com.hubspot.jinjava.features.BuiltInFeatures;
 
 public class TokenScanner extends AbstractIterator<Token> {
 
@@ -93,7 +94,12 @@ private Token getNextToken() {
         if (currPost < length) {
           c = is[currPost];
           boolean startTokenFound = true;
-          if (config.getLegacyOverrides().isWhitespaceRequiredWithinTokens()) {
+          if (
+            config
+              .getFeatures()
+              .isActive(BuiltInFeatures.WHITESPACE_REQUIRED_WITHIN_TOKENS) ||
+            config.getLegacyOverrides().isWhitespaceRequiredWithinTokens()
+          ) {
             boolean hasNextChar = (currPost + 1) < length;
             boolean nextCharIsWhitespace = hasNextChar && (' ' == is[currPost + 1]);
             startTokenFound = nextCharIsWhitespace;

src/test/java/com/hubspot/jinjava/FeaturesTest.java

@@ -47,7 +47,7 @@ public void setUp() throws Exception {
               ZonedDateTime.of(LocalDateTime.MAX, ZoneId.systemDefault())
             )
           )
-          .add(DELEGATING, d -> delegateActive)
+          .add(DELEGATING, () -> delegateActive)
           .build()
       );
   }