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Add NBTPath#of(Tag, Tag) #2

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0ce1c57
Add NBTPath#of(Tag, Tag)
Taskeren Jun 7, 2026
6feb8db
Add throwing information
Taskeren Jun 7, 2026
2436731
Add NBTPath#toPathString
Taskeren Jun 8, 2026
7617c8c
Fix
Taskeren Jun 8, 2026
656c87b
Merge tests
Taskeren Jun 8, 2026
3e247e8
Fix doc
Taskeren Jun 9, 2026
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44 changes: 44 additions & 0 deletions src/main/java/org/glavo/nbt/NBTPath.java
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Original file line number Diff line number Diff line change
Expand Up @@ -16,12 +16,16 @@
package org.glavo.nbt;

import org.glavo.nbt.internal.path.NBTPathImpl;
import org.glavo.nbt.internal.path.NBTPathNode;
import org.glavo.nbt.internal.snbt.SNBTParser;
import org.glavo.nbt.tag.ParentTag;
import org.glavo.nbt.tag.Tag;
import org.glavo.nbt.tag.TagType;
import org.jetbrains.annotations.Contract;
import org.jetbrains.annotations.Nullable;

import java.util.*;

/// An NBT path is a descriptive string used to specify one or more particular elements from an NBT data tree.
///
/// @see <a href="https://minecraft.wiki/w/NBT_path">NBT Path - Minecraft Wiki</a>
Expand All @@ -34,6 +38,34 @@ static NBTPath<?> of(String path) throws IllegalArgumentException {
return new SNBTParser(path, 0, path.length()).nextPath();
}

/// Get the path from the root tag to the given tag.
///
/// @param expectedRoot the expected root instead of the top of the tree.
/// @return the path or `null` if parent is null.
/// @throws IllegalStateException when the expected root doesn't match the actual root.
@SuppressWarnings({"DataFlowIssue", "unchecked"})
@Contract(pure = true)
static @Nullable <T extends Tag> NBTPath<T> of(T tag, @Nullable Tag expectedRoot) throws IllegalArgumentException, IllegalStateException {
ParentTag<?> parentTag = tag.getParentTag();

@Glavo Glavo Jun 16, 2026

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本审查建议由 GPT-5 生成

[P2] 这里改用 tag.getParentTag() 会把 parent 是 Chunk 的 rootTag 当成“没有 parent”。但 Tag#getParent() 允许 parent 是 Chunk，NBTPathImpl.select 也支持从 Chunk 查询。结果是 NBTPath.of(chunk.getRootTag(), null) 返回 null，而 chunk 内部子 tag 也无法自然生成相对 Chunk 可用的 path，调用方必须额外知道并传入 chunk.getRootTag()，和 NBTParent 支持的根类型不一致。

if (parentTag == null) return null;

List<NBTPathNode> paths = new ArrayList<>();
paths.add(NBTPathImpl.getIndicator(tag));
while (true) {
if (parentTag == expectedRoot) break;
paths.add(NBTPathImpl.getIndicator(parentTag));
ParentTag<?> parent = parentTag.getParentTag();
if (parent == null) break;
parentTag = parent;
}

if (parentTag != expectedRoot)

@Glavo Glavo Jun 16, 2026

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本审查建议由 GPT-5 生成

[P2] expectedRoot == null 会让非根 tag 固定抛 IllegalStateException。例如 root.addTag("x", tag) 后调用 NBTPath.of(tag, null)，循环会停在实际 top root，随后这里的 parentTag != expectedRoot 恒为 true。这个 nullable 参数看起来应支持“使用实际 top of tree”，但当前实现只在显式传入 root tag 时可用，测试也没有覆盖 null root。

throw new IllegalStateException("Unexpected root tag " + parentTag + ", expected " + expectedRoot + ".");
Collections.reverse(paths);
NBTPathNode[] nodes = paths.toArray(NBTPathNode[]::new);
return (NBTPath<T>) new NBTPathImpl<>(nodes, tag.getType());
}

/// Returns the tag type of this path.
@Contract(pure = true)
@Nullable TagType<T> getTagType();
Expand All @@ -50,4 +82,16 @@ static NBTPath<?> of(String path) throws IllegalArgumentException {
@Contract(pure = true)
<T2 extends Tag> NBTPath<T2> withTagType(TagType<T2> tagType) throws IllegalStateException;

/// Returns the path string.
///
/// @param omitDots `true` to omit dots if possible.
@Contract(pure = true)
String toPathString(boolean omitDots);

/// Returns the path string with dots omitted if possible.
@Contract(pure = true)
default String toPathString() {
return toPathString(true);
}

}
55 changes: 31 additions & 24 deletions src/main/java/org/glavo/nbt/internal/path/NBTPathImpl.java
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Expand Up @@ -22,6 +22,7 @@
import org.glavo.nbt.internal.snbt.SNBTWriter;
import org.glavo.nbt.io.SNBTCodec;
import org.glavo.nbt.tag.CompoundTag;
import org.glavo.nbt.tag.ParentTag;
import org.glavo.nbt.tag.Tag;
import org.glavo.nbt.tag.TagType;
import org.jetbrains.annotations.Nullable;
Expand Down Expand Up @@ -59,6 +60,14 @@ public static <T extends Tag> Stream<T> select(NBTParent<?> parent, NBTPath<? ex
return (Stream<T>) tags;
}

/// Get the indicator of the given tag, depends on its parent tag.
///
/// @return the name node if parent is [CompoundTag], the index node if parent is other [ParentTag], or `null` if parent is null.
public static @Nullable NBTPathNode getIndicator(Tag tag) {
ParentTag<?> parentTag = tag.getParentTag();
return parentTag == null ? null : parentTag instanceof CompoundTag ? new NBTPathNode.NamedSubTag(tag.getName()) : new NBTPathNode.Index(tag.getIndex());
}

private final NBTPathNode @Unmodifiable [] nodes;
private final @Nullable TagType<T> tagType;

Expand Down Expand Up @@ -107,33 +116,31 @@ public int hashCode() {
}

@Override
public String toString() {
if (cachedString == null) {
StringBuilder builder = new StringBuilder();

if (tagType != null) {
builder.append("<").append(tagType).append("> ");
public String toPathString(boolean omitDots) {
StringBuilder builder = new StringBuilder();

SNBTWriter<StringBuilder> writer = new SNBTWriter<>(SNBTCodec.ofCompact(), builder);
for (int i = 0; i < nodes.length; i++) {
NBTPathNode node = nodes[i];
try {
node.appendTo(writer);
} catch (IOException e) {
throw new AssertionError(e);
}

var writer = new SNBTWriter<>(SNBTCodec.ofCompact(), builder);

boolean first = true;
for (NBTPathNode node : nodes) {
if (first) {
first = false;
} else if (node.needDot()) {
writer.getAppendable().append('.');
}

try {
node.appendTo(writer);
} catch (IOException e) {
throw new AssertionError(e);
}
if (i + 1 < nodes.length && (!omitDots || nodes[i + 1].needDot())) {
writer.getAppendable().append('.');
}
}

return builder.toString();
}

builder.append(']');
cachedString = builder.toString();
@Override
public String toString() {
if (cachedString == null) {
String pathString = toPathString();
if (tagType != null) pathString = "<" + tagType + ">" + " " + pathString;
cachedString = pathString;
}

return cachedString;
Expand Down
97 changes: 91 additions & 6 deletions src/test/java/org/glavo/nbt/NBTPathTest.java
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Expand Up @@ -21,12 +21,8 @@

import java.util.List;

import static org.junit.jupiter.api.Assertions.assertEquals;
import static org.junit.jupiter.api.Assertions.assertIterableEquals;
import static org.junit.jupiter.api.Assertions.assertNotEquals;
import static org.junit.jupiter.api.Assertions.assertNull;
import static org.junit.jupiter.api.Assertions.assertSame;
import static org.junit.jupiter.api.Assertions.assertThrows;
import static org.junit.jupiter.api.Assertions.*;
import static org.junit.jupiter.api.Assertions.assertNotNull;

final class NBTPathTest {

Expand Down Expand Up @@ -188,4 +184,93 @@ void testInvalidPathSyntax() {
assertThrows(IllegalArgumentException.class, () -> NBTPath.of("\"unterminated"));
assertThrows(IllegalArgumentException.class, () -> NBTPath.of("[2147483648]"));
}

@Test
void testPathString() {
assertEquals("{}", NBTPath.of("{}").toPathString());
assertEquals("{Invisible:1B}", NBTPath.of("{Invisible:1b}").toPathString());
assertEquals("\"A Very Cool Name[]\"", NBTPath.of("\"A Very Cool Name[]\"").toPathString());
assertEquals("\"A Very Cool Name[]\"{}", NBTPath.of("\"A Very Cool Name[]\"{}").toPathString());
assertEquals("\"A Very Cool Name[]\"[]", NBTPath.of("\"A Very Cool Name[]\"[]").toPathString());
assertEquals("\"A Very Cool Name[]\"[{}]", NBTPath.of("\"A Very Cool Name[]\"[{}]").toPathString());
assertEquals("\"A Very Cool Name[]\"[{Count:25B}]", NBTPath.of("\"A Very Cool Name[]\"[{Count:25b}]").toPathString());
assertEquals("\"A Very Cool Name[]\"[][][]", NBTPath.of("\"A Very Cool Name[]\"[][][]").toPathString());
assertEquals("foo.bar", NBTPath.of("foo.bar").toPathString());
assertEquals("foo.bar[]", NBTPath.of("foo.bar.[]").toPathString());
assertEquals("foo.bar[{}]", NBTPath.of("foo.bar.[{}]").toPathString());
assertEquals("foo.bar[0]", NBTPath.of("foo.bar.[0]").toPathString());
assertEquals("foo.bar[-1]", NBTPath.of("foo.bar.[-1]").toPathString());
assertEquals("foo.bar.\"0123\"", NBTPath.of("foo.bar.\"0123\"").toPathString());
}

@Test
void testPathStringKeepDots() {
assertEquals("{}", NBTPath.of("{}").toPathString(false));
assertEquals("{Invisible:1B}", NBTPath.of("{Invisible:1b}").toPathString(false));
assertEquals("\"A Very Cool Name[]\"", NBTPath.of("\"A Very Cool Name[]\"").toPathString(false));
assertEquals("\"A Very Cool Name[]\"{}", NBTPath.of("\"A Very Cool Name[]\"{}").toPathString(false));
assertEquals("\"A Very Cool Name[]\".[]", NBTPath.of("\"A Very Cool Name[]\"[]").toPathString(false));
assertEquals("\"A Very Cool Name[]\".[{}]", NBTPath.of("\"A Very Cool Name[]\"[{}]").toPathString(false));
assertEquals("\"A Very Cool Name[]\".[{Count:25B}]", NBTPath.of("\"A Very Cool Name[]\"[{Count:25b}]").toPathString(false));
assertEquals("\"A Very Cool Name[]\".[].[].[]", NBTPath.of("\"A Very Cool Name[]\"[][][]").toPathString(false));
assertEquals("foo.bar", NBTPath.of("foo.bar").toPathString(false));
assertEquals("foo.bar.[]", NBTPath.of("foo.bar.[]").toPathString(false));
assertEquals("foo.bar.[{}]", NBTPath.of("foo.bar.[{}]").toPathString(false));
assertEquals("foo.bar.[0]", NBTPath.of("foo.bar.[0]").toPathString(false));
assertEquals("foo.bar.[-1]", NBTPath.of("foo.bar.[-1]").toPathString(false));
assertEquals("foo.bar.\"0123\"", NBTPath.of("foo.bar.\"0123\"").toPathString(false));
}

@Test
void testOfPath() {
CompoundTag root = new CompoundTag().setName("root");
IntTag tag;

root.addTag("foo", new CompoundTag()
.addTag("bar", new ListTag<IntTag>()
.addTag(new IntTag(0))
.addTag(new IntTag(1))
.addTag(tag = new IntTag(2))
));

NBTPath<IntTag> pathTo2 = NBTPath.of(tag, root);
assertNotNull(pathTo2);
assertEquals(2, root.getFirstInt(pathTo2));
assertEquals(NBTPath.of("foo.bar[2]").withTagType(TagType.INT), pathTo2);
}

@Test
void testOfPath2() {
CompoundTag root = new CompoundTag().setName("root");
CompoundTag expectedRoot;
IntTag tag;

root.addTag("foo", expectedRoot = new CompoundTag()
.addTag("bar", new CompoundTag()
.addTag("baz", new ListTag<IntTag>()
.addTag(new IntTag(0))
.addTag(new IntTag(1))
.addTag(tag = new IntTag(2))
)));

NBTPath<IntTag> pathTo2 = NBTPath.of(tag, expectedRoot);
assertNotNull(pathTo2);
assertEquals(2, expectedRoot.getFirstInt(pathTo2));
assertEquals(NBTPath.of("bar.baz[2]").withTagType(TagType.INT), pathTo2);
}

@Test
void testOfPath3() {
CompoundTag root = new CompoundTag().setName("root");
StringTag tag;

root.addTag("Very Cool Name", new CompoundTag()
.addTag("bar", new CompoundTag()
.addTag("baz", tag = new StringTag(":D"))));

NBTPath<StringTag> pathToSmile = NBTPath.of(tag, root);
assertNotNull(pathToSmile);
assertEquals(":D", root.getFirstString(pathToSmile));
assertEquals(NBTPath.of("\"Very Cool Name\".bar.baz").withTagType(TagType.STRING), pathToSmile);
}
}
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