feat: backport configurable delimiters, backslash handling & keepTrailingNewline to 2.8.x

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

@@ -250,7 +250,7 @@ public RenderResult renderForResult(
         .getInterpreterFactory()
         .newInstance(this, context, renderConfig);
       try {
-        String result = interpreter.render(template);
+        String result = stripTrailingNewlineIfNeeded(interpreter.render(template));
         return new RenderResult(
           result,
           interpreter.getContext(),
@@ -293,6 +293,18 @@ public RenderResult renderForResult(
     }
   }
 
+  /**
+   * Strips a single trailing newline from the rendered output when
+   * {@code keepTrailingNewline} is {@code false} in {@link JinjavaConfig},
+   * matching Python Jinja2's default behaviour.
+   */
+  private String stripTrailingNewlineIfNeeded(String output) {
+    if (!globalConfig.isKeepTrailingNewline() && output.endsWith("\n")) {
+      return output.substring(0, output.length() - 1);
+    }
+    return output;
+  }
+
   /**
    * Creates a new interpreter instance using the global context and global config
    *

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

@@ -89,6 +89,7 @@ public class JinjavaConfig {
   private final LegacyOverrides legacyOverrides;
   private final boolean enablePreciseDivideFilter;
   private final boolean enableFilterChainOptimization;
+  private final boolean keepTrailingNewline;
   private final ObjectMapper objectMapper;
 
   private final Features features;
@@ -153,6 +154,10 @@ private JinjavaConfig(Builder builder) {
     dateTimeProvider = builder.dateTimeProvider;
     enablePreciseDivideFilter = builder.enablePreciseDivideFilter;
     enableFilterChainOptimization = builder.enableFilterChainOptimization;
+    keepTrailingNewline =
+      builder.keepTrailingNewline != null
+        ? builder.keepTrailingNewline
+        : legacyOverrides.getDefaultKeepTrailingNewlineBehavior();
     objectMapper = setupObjectMapper(builder.objectMapper);
     objectUnwrapper = builder.objectUnwrapper;
     processors = builder.processors;
@@ -313,6 +318,17 @@ public boolean isEnableFilterChainOptimization() {
     return enableFilterChainOptimization;
   }
 
+  /**
+   * When {@code false}, a single trailing newline is stripped from the rendered output,
+   * matching Python Jinja2's default.
+   * When {@code true}, the trailing newline of the rendered output is preserved —
+   * matching Jinjava's historical behaviour.
+   * Defaults to {@link LegacyOverrides#getDefaultKeepTrailingNewlineBehavior()}.
+   */
+  public boolean isKeepTrailingNewline() {
+    return keepTrailingNewline;
+  }
+
   public DateTimeProvider getDateTimeProvider() {
     return dateTimeProvider;
   }
@@ -356,6 +372,7 @@ public static class Builder {
     private LegacyOverrides legacyOverrides = LegacyOverrides.NONE;
     private boolean enablePreciseDivideFilter = false;
     private boolean enableFilterChainOptimization = false;
+    private Boolean keepTrailingNewline = null;
     private ObjectMapper objectMapper = null;
 
     private ObjectUnwrapper objectUnwrapper = new JinjavaObjectUnwrapper();
@@ -534,6 +551,11 @@ public Builder withEnableFilterChainOptimization(
       return this;
     }
 
+    public Builder withKeepTrailingNewline(boolean keepTrailingNewline) {
+      this.keepTrailingNewline = keepTrailingNewline;
+      return this;
+    }
+
     public Builder withObjectMapper(ObjectMapper objectMapper) {
       this.objectMapper = objectMapper;
       return this;

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

@@ -19,6 +19,8 @@ public class LegacyOverrides {
     .withAllowAdjacentTextNodes(true)
     .withUseTrimmingForNotesAndExpressions(true)
     .withKeepNullableLoopValues(true)
+    .withHandleBackslashInQuotesOnly(true)
+    .withDefaultKeepTrailingNewlineBehavior(false)
     .build();
   private final boolean evaluateMapKeys;
   private final boolean iterateOverMapKeys;
@@ -30,6 +32,8 @@ public class LegacyOverrides {
   private final boolean allowAdjacentTextNodes;
   private final boolean useTrimmingForNotesAndExpressions;
   private final boolean keepNullableLoopValues;
+  private final boolean handleBackslashInQuotesOnly;
+  private final boolean defaultKeepTrailingNewlineBehavior;
 
   private LegacyOverrides(Builder builder) {
     evaluateMapKeys = builder.evaluateMapKeys;
@@ -42,6 +46,8 @@ private LegacyOverrides(Builder builder) {
     allowAdjacentTextNodes = builder.allowAdjacentTextNodes;
     useTrimmingForNotesAndExpressions = builder.useTrimmingForNotesAndExpressions;
     keepNullableLoopValues = builder.keepNullableLoopValues;
+    handleBackslashInQuotesOnly = builder.handleBackslashInQuotesOnly;
+    defaultKeepTrailingNewlineBehavior = builder.defaultKeepTrailingNewlineBehavior;
   }
 
   public static Builder newBuilder() {
@@ -88,6 +94,19 @@ public boolean isKeepNullableLoopValues() {
     return keepNullableLoopValues;
   }
 
+  public boolean isHandleBackslashInQuotesOnly() {
+    return handleBackslashInQuotesOnly;
+  }
+
+  /**
+   * The default value of {@link JinjavaConfig#isKeepTrailingNewline()}.
+   * {@code true} preserves Jinjava's historical behaviour of keeping the trailing newline;
+   * {@code false} matches Python Jinja2's default of stripping it.
+   */
+  public boolean getDefaultKeepTrailingNewlineBehavior() {
+    return defaultKeepTrailingNewlineBehavior;
+  }
+
   public static class Builder {
 
     private boolean evaluateMapKeys = false;
@@ -100,6 +119,8 @@ public static class Builder {
     private boolean allowAdjacentTextNodes = false;
     private boolean useTrimmingForNotesAndExpressions = false;
     private boolean keepNullableLoopValues = false;
+    private boolean handleBackslashInQuotesOnly = false;
+    private boolean defaultKeepTrailingNewlineBehavior = true;
 
     private Builder() {}
 
@@ -123,6 +144,10 @@ public static Builder from(LegacyOverrides legacyOverrides) {
         .withAllowAdjacentTextNodes(legacyOverrides.allowAdjacentTextNodes)
         .withUseTrimmingForNotesAndExpressions(
           legacyOverrides.useTrimmingForNotesAndExpressions
+        )
+        .withHandleBackslashInQuotesOnly(legacyOverrides.handleBackslashInQuotesOnly)
+        .withDefaultKeepTrailingNewlineBehavior(
+          legacyOverrides.defaultKeepTrailingNewlineBehavior
         );
     }
 
@@ -187,5 +212,17 @@ public Builder withKeepNullableLoopValues(boolean keepNullableLoopValues) {
       this.keepNullableLoopValues = keepNullableLoopValues;
       return this;
     }
+
+    public Builder withHandleBackslashInQuotesOnly(boolean handleBackslashInQuotesOnly) {
+      this.handleBackslashInQuotesOnly = handleBackslashInQuotesOnly;
+      return this;
+    }
+
+    public Builder withDefaultKeepTrailingNewlineBehavior(
+      boolean defaultKeepTrailingNewlineBehavior
+    ) {
+      this.defaultKeepTrailingNewlineBehavior = defaultKeepTrailingNewlineBehavior;
+      return this;
+    }
   }
 }

src/main/java/com/hubspot/jinjava/tree/TreeParser.java

@@ -32,13 +32,15 @@
 import com.hubspot.jinjava.lib.tag.FlexibleTag;
 import com.hubspot.jinjava.lib.tag.Tag;
 import com.hubspot.jinjava.tree.parse.ExpressionToken;
+import com.hubspot.jinjava.tree.parse.StringTokenScanner;
 import com.hubspot.jinjava.tree.parse.TagToken;
 import com.hubspot.jinjava.tree.parse.TextToken;
 import com.hubspot.jinjava.tree.parse.Token;
 import com.hubspot.jinjava.tree.parse.TokenScanner;
 import com.hubspot.jinjava.tree.parse.TokenScannerSymbols;
 import com.hubspot.jinjava.tree.parse.UnclosedToken;
 import com.hubspot.jinjava.tree.parse.WhitespaceControlParser;
+import java.util.Iterator;
 import org.apache.commons.lang3.StringUtils;
 
 public class TreeParser {
@@ -52,7 +54,7 @@ public class TreeParser {
 
   public TreeParser(JinjavaInterpreter interpreter, String input) {
     this.scanner =
-      Iterators.peekingIterator(new TokenScanner(input, interpreter.getConfig()));
+      Iterators.peekingIterator(createScanner(input, interpreter.getConfig()));
     this.interpreter = interpreter;
     this.symbols = interpreter.getConfig().getTokenScannerSymbols();
     this.whitespaceControlParser =
@@ -104,6 +106,13 @@ public Node buildTree() {
     return root;
   }
 
+  private static Iterator<Token> createScanner(String input, JinjavaConfig config) {
+    if (config.getTokenScannerSymbols().isStringBased()) {
+      return new StringTokenScanner(input, config);
+    }
+    return new TokenScanner(input, config);
+  }
+
   /**
    * @return null if EOF or error
    */

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

@@ -54,7 +54,14 @@ public int getType() {
 
   @Override
   protected void parse() {
-    this.expr = WhitespaceUtils.unwrap(image, "{{", "}}");
+    // Use the symbols-derived delimiter strings instead of the hardcoded "{{" / "}}"
+    // so that custom delimiters (e.g. "\VAR{" / "}") are stripped correctly.
+    this.expr =
+      WhitespaceUtils.unwrap(
+        image,
+        getSymbols().getExpressionStart(),
+        getSymbols().getExpressionEnd()
+      );
     this.expr = handleTrim(expr);
     this.expr = StringUtils.trimToEmpty(this.expr);
   }

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

@@ -48,8 +48,11 @@ public int getType() {
    */
   @Override
   protected void parse() {
-    if (image.length() > 4) { // {# #}
-      handleTrim(image.substring(2, image.length() - 2));
+    int startLen = getSymbols().getCommentStartLength();
+    int endLen = getSymbols().getCommentEndLength();
+
+    if (image.length() > startLen + endLen) {
+      handleTrim(image.substring(startLen, image.length() - endLen));
     }
     content = "";
   }