Add support for newline separated SNBTs

src/main/java/org/glavo/nbt/internal/snbt/SNBTParser.java

@@ -32,6 +32,8 @@
 public final class SNBTParser {
     private final CharSequence input;
     private final int endIndex;
+    /// Whether allows New Line (\n) as separators in Compound and List. Used in FTB-flavored SNBT.
+    private final boolean allowNewLineAsSeparator;
 
     private boolean parsingPath = false;
 
@@ -41,11 +43,22 @@ public final class SNBTParser {
     private @Nullable StringBuilder buffer;
 
     private @Nullable Token lookahead;
+    /// the tokenizeNewLine flag of the corresponding lookahead value, used to check if a re-read is needed.
+    /// the nullability is same to the lookahead, which when lookahead is null, this is null.
+    private @Nullable Boolean lookaheadNewLineParam;
+    /// the cursor to roll back to when the lookahead need to be re-read.
+    /// the nullability is same to the lookahead, which when lookahead is null, this is null.
+    private @Nullable Integer lookaheadCursor;
 
     public SNBTParser(CharSequence input, int beginIndex, int endIndex) {
+        this(input, beginIndex, endIndex, false);
+    }
+
+    public SNBTParser(CharSequence input, int beginIndex, int endIndex, boolean allowNewLineAsSeparator) {
         Objects.checkFromToIndex(beginIndex, endIndex, input.length());
         this.input = input;
         this.endIndex = endIndex;
+        this.allowNewLineAsSeparator = allowNewLineAsSeparator;
 
         this.cursor = beginIndex;
     }
@@ -74,9 +87,12 @@ private StringBuilder getBuilder() {
         return buffer;
     }
 
-    private void skipWhiteSpace() {
+    private void skipWhiteSpace(boolean keepNewLine) {
         while (cursor < endIndex) {
             int ch = getCodePoint();
+            if (allowNewLineAsSeparator && keepNewLine && ch == '\n') {
+                break;
+            }
             if (Character.isWhitespace(ch)) {
                 cursor += Character.charCount(ch);
             } else {
@@ -107,7 +123,11 @@ private boolean isUnquotedStringPart(int ch) {
     }
 
     Token readNextToken() {
-        skipWhiteSpace();
+        return readNextToken(false);
+    }
+
+    Token readNextToken(boolean tokenizeNewLine) {
+        skipWhiteSpace(tokenizeNewLine);
 
         if (cursor >= endIndex) {
             return Token.SimpleToken.EOF;
@@ -145,6 +165,7 @@ Token readNextToken() {
             case '.' -> cursor >= endIndex || !TextUtils.isAsciiDigit(input.charAt(cursor))
                     ? Token.SimpleToken.DOT
                     : null;  // Floating point number
+            case '\n' -> Token.SimpleToken.NEW_LINE; // '\n' will be skipped above unless allowed
             default -> null;
         };
 
@@ -285,6 +306,8 @@ Token nextToken() {
         if (lookahead != null) {
             Token token = lookahead;
             lookahead = null;
+            lookaheadNewLineParam = null;
+            lookaheadCursor = null;
             return token;
         }
         return readNextToken();
@@ -307,8 +330,24 @@ <T extends Token> T nextToken(Class<T> expected) {
     }
 
     Token peekToken() {
-        if (lookahead == null) {
-            lookahead = readNextToken();
+        return peekToken(false);
+    }
+
+    Token peekToken(boolean tokenizeNewLine) {
+        // nullability of lookaheadNewLineParam is same to lookahead.
+        assert (lookahead != null) == (lookaheadNewLineParam != null);
+        assert (lookahead != null) == (lookaheadCursor != null);
+
+        if(lookahead == null) {
+            // preserved the rollback point
+            lookaheadCursor = cursor;
+            lookahead = readNextToken(tokenizeNewLine);
+            lookaheadNewLineParam = tokenizeNewLine;
+        } else if(lookaheadNewLineParam != tokenizeNewLine) {
+            // the flag doesn't match, do the rollback
+            cursor = lookaheadCursor;
+            lookahead = readNextToken(tokenizeNewLine);
+            lookaheadNewLineParam = tokenizeNewLine;
         }
         return lookahead;
     }
@@ -318,6 +357,8 @@ void discardPeekedToken(Token token) {
             throw new AssertionError("Expected " + token + ", but got " + lookahead);
         }
         lookahead = null;
+        lookaheadNewLineParam = null;
+        lookaheadCursor = null;
     }
 
     public @Nullable Tag nextTag() throws IllegalArgumentException {
@@ -400,8 +441,8 @@ private CompoundTag nextCompoundTag(boolean shareEmpty) throws IllegalArgumentEx
 
             tag.addTag(nameToken.value(), value);
 
-            Token peek = peekToken();
-            if (peek == Token.SimpleToken.COMMA) {
+            Token peek = peekToken(true);
+            if (peek == Token.SimpleToken.COMMA || peek == Token.SimpleToken.NEW_LINE) {
                 discardPeekedToken(peek);
             } else if (peek == Token.SimpleToken.RIGHT_BRACE) {
                 discardPeekedToken(peek);
@@ -432,8 +473,8 @@ private ListTag<?> nextListTag() throws IllegalArgumentException {
             }
             tag.addAnyTag(value);
 
-            peek = peekToken();
-            if (peek == Token.SimpleToken.COMMA) {
+            peek = peekToken(true);
+            if (peek == Token.SimpleToken.COMMA || peek == Token.SimpleToken.NEW_LINE) {
                 discardPeekedToken(peek);
             } else if (peek == Token.SimpleToken.RIGHT_BRACKET) {
                 discardPeekedToken(peek);

src/main/java/org/glavo/nbt/internal/snbt/Token.java

@@ -34,6 +34,7 @@ enum SimpleToken implements Token {
         COMMA,              // ,
         COLON,              // :
         DOT,                // .
+        NEW_LINE,           // \n
         EOF
     }
 

src/main/java/org/glavo/nbt/io/SNBTCodec.java

@@ -83,17 +83,17 @@ public final class SNBTCodec {
             SurroundingSpaces.COMPACT,
             EscapeStrategy.defaultStrategy(),
             QuoteStrategy.defaultNameStrategy(),
-            QuoteStrategy.defaultValueStrategy()
-    );
+            QuoteStrategy.defaultValueStrategy(),
+            false);
 
     private static final SNBTCodec PRETTY = new SNBTCodec(
             LineBreakStrategy.defaultStrategy(),
             "    ", // 4 spaces
             SurroundingSpaces.PRETTY,
             EscapeStrategy.defaultStrategy(),
             QuoteStrategy.defaultNameStrategy(),
-            QuoteStrategy.defaultValueStrategy()
-    );
+            QuoteStrategy.defaultValueStrategy(),
+            false);
 
     public static SNBTCodec of() {
         return PRETTY;
@@ -110,14 +110,17 @@ public static SNBTCodec ofCompact() {
     private final EscapeStrategy escapeStrategy;
     private final QuoteStrategy nameQuoteStrategy;
     private final QuoteStrategy valueQuoteStrategy;
+    private final boolean allowNewLineAsSeparator;
 
-    private SNBTCodec(LineBreakStrategy lineBreakStrategy, String indentation, SurroundingSpaces surroundingSpaces, EscapeStrategy escapeStrategy, QuoteStrategy nameQuoteStrategy, QuoteStrategy valueQuoteStrategy) {
+    private SNBTCodec(LineBreakStrategy lineBreakStrategy, String indentation, SurroundingSpaces surroundingSpaces,
+                      EscapeStrategy escapeStrategy, QuoteStrategy nameQuoteStrategy, QuoteStrategy valueQuoteStrategy, boolean allowNewLineAsSeparator) {
         this.lineBreakStrategy = lineBreakStrategy;
         this.indentation = indentation;
         this.surroundingSpaces = surroundingSpaces;
         this.escapeStrategy = escapeStrategy;
         this.nameQuoteStrategy = nameQuoteStrategy;
         this.valueQuoteStrategy = valueQuoteStrategy;
+        this.allowNewLineAsSeparator = allowNewLineAsSeparator;
     }
 
     /// Returns the line break strategy for all parent tags.
@@ -136,7 +139,7 @@ public LineBreakStrategy getLineBreakStrategy() {
     @Contract(value = "_ -> new", pure = true)
     public SNBTCodec withLineBreakStrategy(LineBreakStrategy strategy) {
         Objects.requireNonNull(strategy, "strategy");
-        return new SNBTCodec(strategy, indentation, surroundingSpaces, escapeStrategy, nameQuoteStrategy, valueQuoteStrategy);
+        return new SNBTCodec(strategy, indentation, surroundingSpaces, escapeStrategy, nameQuoteStrategy, valueQuoteStrategy, allowNewLineAsSeparator);
     }
 
     /// Returns the indentation string before each line.
@@ -160,7 +163,7 @@ public SNBTCodec withIndentation(String indentation) {
             }
         }
 
-        return new SNBTCodec(lineBreakStrategy, indentation, surroundingSpaces, escapeStrategy, nameQuoteStrategy, valueQuoteStrategy);
+        return new SNBTCodec(lineBreakStrategy, indentation, surroundingSpaces, escapeStrategy, nameQuoteStrategy, valueQuoteStrategy, allowNewLineAsSeparator);
 
     }
 
@@ -172,7 +175,7 @@ public SNBTCodec withIndentation(String indentation) {
     /// @see #withIndentation(String)
     @Contract(value = "_ -> new", pure = true)
     public SNBTCodec withIndentation(int spaces) {
-        return new SNBTCodec(lineBreakStrategy, " ".repeat(spaces), surroundingSpaces, escapeStrategy, nameQuoteStrategy, valueQuoteStrategy);
+        return new SNBTCodec(lineBreakStrategy, " ".repeat(spaces), surroundingSpaces, escapeStrategy, nameQuoteStrategy, valueQuoteStrategy, allowNewLineAsSeparator);
     }
 
     /// Returns the surrounding spaces for SNBT.
@@ -185,7 +188,7 @@ public SurroundingSpaces getSurroundingSpaces() {
     @Contract(value = "_ -> new", pure = true)
     public SNBTCodec withSurroundingSpaces(SurroundingSpaces surroundingSpaces) {
         Objects.requireNonNull(surroundingSpaces, "surroundingSpaces");
-        return new SNBTCodec(lineBreakStrategy, indentation, surroundingSpaces, escapeStrategy, nameQuoteStrategy, valueQuoteStrategy);
+        return new SNBTCodec(lineBreakStrategy, indentation, surroundingSpaces, escapeStrategy, nameQuoteStrategy, valueQuoteStrategy, allowNewLineAsSeparator);
     }
 
     /// Returns the escape strategy for SNBT.
@@ -204,7 +207,7 @@ public EscapeStrategy getEscapeStrategy() {
     @Contract(value = "_ -> new", pure = true)
     public SNBTCodec withEscapeStrategy(EscapeStrategy escapeStrategy) {
         Objects.requireNonNull(escapeStrategy, "escapeStrategy");
-        return new SNBTCodec(lineBreakStrategy, indentation, surroundingSpaces, escapeStrategy, nameQuoteStrategy, valueQuoteStrategy);
+        return new SNBTCodec(lineBreakStrategy, indentation, surroundingSpaces, escapeStrategy, nameQuoteStrategy, valueQuoteStrategy, allowNewLineAsSeparator);
     }
 
     /// Returns the quote strategy for SNBT tag names.
@@ -223,7 +226,7 @@ public QuoteStrategy getNameQuoteStrategy() {
     @Contract(value = "_ -> new", pure = true)
     public SNBTCodec withNameQuoteStrategy(QuoteStrategy quoteStrategy) {
         Objects.requireNonNull(quoteStrategy, "quoteStrategy");
-        return new SNBTCodec(lineBreakStrategy, indentation, surroundingSpaces, escapeStrategy, quoteStrategy, valueQuoteStrategy);
+        return new SNBTCodec(lineBreakStrategy, indentation, surroundingSpaces, escapeStrategy, quoteStrategy, valueQuoteStrategy, allowNewLineAsSeparator);
     }
 
     /// Returns the quote strategy for SNBT tag values.
@@ -242,7 +245,17 @@ public QuoteStrategy getValueQuoteStrategy() {
     @Contract(value = "_ -> new", pure = true)
     public SNBTCodec withValueQuoteStrategy(QuoteStrategy quoteStrategy) {
         Objects.requireNonNull(quoteStrategy, "quoteStrategy");
-        return new SNBTCodec(lineBreakStrategy, indentation, surroundingSpaces, escapeStrategy, nameQuoteStrategy, quoteStrategy);
+        return new SNBTCodec(lineBreakStrategy, indentation, surroundingSpaces, escapeStrategy, nameQuoteStrategy, quoteStrategy, allowNewLineAsSeparator);
+    }
+
+    @Contract(pure = true)
+    public boolean getAllowNewLineAsSeparator() {
+        return allowNewLineAsSeparator;
+    }
+
+    @Contract(pure = true)
+    public SNBTCodec withAllowNewLineAsSeparator(boolean allowNewLineAsSeparator) {
+        return new SNBTCodec(lineBreakStrategy, indentation, surroundingSpaces, escapeStrategy, nameQuoteStrategy, valueQuoteStrategy, allowNewLineAsSeparator);
     }
 
     /// Reads a NBT tag from the Stringified NBT data.
@@ -261,7 +274,7 @@ public Tag readTag(CharSequence input) throws IOException {
     public Tag readTag(CharSequence input, int startInclusive, int endExclusive) throws IOException {
         Tag tag;
         try {
-            tag = new SNBTParser(input, startInclusive, endExclusive).nextTag();
+            tag = new SNBTParser(input, startInclusive, endExclusive, allowNewLineAsSeparator).nextTag();
         } catch (IllegalArgumentException e) {
             throw new IOException(e);
         }
@@ -324,12 +337,13 @@ public boolean equals(Object o) {
                 && this.surroundingSpaces.equals(that.surroundingSpaces)
                 && this.escapeStrategy.equals(that.escapeStrategy)
                 && this.nameQuoteStrategy.equals(that.nameQuoteStrategy)
-                && this.valueQuoteStrategy.equals(that.valueQuoteStrategy);
+                && this.valueQuoteStrategy.equals(that.valueQuoteStrategy)
+                && this.allowNewLineAsSeparator == that.allowNewLineAsSeparator;
     }
 
     @Override
     public int hashCode() {
-        return Objects.hash(lineBreakStrategy, indentation, surroundingSpaces, escapeStrategy, nameQuoteStrategy, valueQuoteStrategy);
+        return Objects.hash(lineBreakStrategy, indentation, surroundingSpaces, escapeStrategy, nameQuoteStrategy, valueQuoteStrategy, allowNewLineAsSeparator);
     }
 
     @Override

src/test/java/org/glavo/nbt/io/SNBTCodecTest.java

@@ -0,0 +1,74 @@
+/*
+ * Copyright 2026 Taskeren
+ *
+ * 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.glavo.nbt.io;
+
+import org.glavo.nbt.TestResources;
+import org.glavo.nbt.tag.CompoundTag;
+import org.glavo.nbt.tag.IntTag;
+import org.glavo.nbt.tag.ListTag;
+import org.glavo.nbt.tag.TagType;
+import org.junit.jupiter.api.Assertions;
+import org.junit.jupiter.api.Test;
+
+import java.io.IOException;
+import java.nio.charset.StandardCharsets;
+import java.nio.file.Files;
+import java.nio.file.Path;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertInstanceOf;
+
+public final class SNBTCodecTest {
+
+    @Test
+    void testNewLineSeparatedSNBT() throws IOException {
+        Path resource = TestResources.getResource("/assets/nbt/newline_separated.snbt");
+        // expected failure
+        // the vanilla-flavored SNBT should not split compounds and lists with '\n'.
+        Assertions.assertThrows(
+            IOException.class, () -> {
+                try (var reader = Files.newBufferedReader(resource, StandardCharsets.UTF_8)) {
+                    SNBTCodec.of().readTag(reader);
+                }
+            });
+
+        try (var reader = Files.newBufferedReader(resource, StandardCharsets.UTF_8)) {
+            var tag = SNBTCodec.of().withAllowNewLineAsSeparator(true).readTag(reader);
+            var compound = assertInstanceOf(CompoundTag.class, tag);
+            assertEquals("Foo", compound.getString("name"));
+            // check list
+            var list = assertInstanceOf(ListTag.class, compound.get("list"));
+            assert list != null : "ensured by assertInstanceOf";
+            assertEquals(TagType.INT, list.getElementType());
+            assertEquals(new ListTag<>(TagType.INT).setName("list")
+                    .addTag(new IntTag(1))
+                    .addTag(new IntTag(2))
+                    .addTag(new IntTag(3))
+                    .addTag(new IntTag(4)), list);
+            // check compound
+            var strDict = assertInstanceOf(CompoundTag.class, compound.get("str_dict"));
+            assertEquals(new CompoundTag()
+                    .setName("str_dict")
+                    .setString("a", "foo")
+                    .setString("b", "bar")
+                    .setString("c", "baz")
+                    .setString("d", "Hello\nWorld")
+                    .setIntArray("e", new int[] {-886784530, 1488270925, -1459824571, -372109282})
+                    .setBoolean("f", true), strDict);
+        }
+    }
+
+}

src/test/resources/assets/nbt/newline_separated.snbt

@@ -0,0 +1,18 @@
+{
+    name: "Foo"
+    list: [
+        1
+        2
+        3
+        4
+    ]
+    str_dict: {
+        a: foo
+        b: bar
+        c: baz
+        d: "Hello
+World"
+        e: uuid(cb24bdee-58b5-364d-a8fc-d845e9d2101e)
+        f: bool(1)
+    }
+}