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Fix WKTWriter invalid dimensional EMPTY tokens for nested empty geometries #1225

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Fix WKTWriter invalid dimensional EMPTY tokens for nested empty geometries #1225

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23 changes: 17 additions & 6 deletions modules/core/src/main/java/org/locationtech/jts/io/WKTWriter.java
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Original file line number Diff line number Diff line change
Expand Up @@ -731,6 +731,17 @@ private void appendOrdinateText(EnumSet<Ordinate> outputOrdinates, Writer writer
writer.append(WKTConstants.M);
}

/**
* Appends the {@code EMPTY} token, inserting a separator after any dimensional
* marker written by {@link #appendOrdinateText}.
*/
private void appendEmptyText(EnumSet<Ordinate> outputOrdinates, Writer writer) throws IOException {
if (outputOrdinates.contains(Ordinate.Z) || outputOrdinates.contains(Ordinate.M)) {
writer.write(" ");
}
writer.write(WKTConstants.EMPTY);
}
Comment on lines +738 to +743

@grootstebozewolf grootstebozewolf Sep 3, 2026

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Right cut. appendOrdinateText writes Z/M/ZM with no trailing space, and existing goldens pin non-empty WKT as POINT Z(1 1 1), not Z (. Do not “fix” this by adding a trailing space on the ordinate marker — that would change every dimensional token.

Spacing only before EMPTY when Z or M is present also keeps XY as POINT EMPTY: the tagged writer already wrote the space after the type, so this helper must not add a second one.


/**
* Appends all members of a <code>CoordinateSequence</code> to the stream. Each {@code Coordinate} is separated from
* another using a colon, the ordinates of a {@code Coordinate} are separated by a space.
Expand All @@ -748,7 +759,7 @@ private void appendSequenceText(CoordinateSequence seq, EnumSet<Ordinate> output
throws IOException
{
if (seq.size() == 0) {
writer.write(WKTConstants.EMPTY);
appendEmptyText(outputOrdinates, writer);
}
else {
if (indentFirst) indent(useFormatting, level, writer);
Expand Down Expand Up @@ -785,7 +796,7 @@ private void appendPolygonText(
throws IOException
{
if (polygon.isEmpty()) {
writer.write(WKTConstants.EMPTY);
appendEmptyText(outputOrdinates, writer);
}
else {
if (indentFirst) indent(useFormatting, level, writer);
Expand Down Expand Up @@ -817,7 +828,7 @@ private void appendMultiPointText(
throws IOException
{
if (multiPoint.getNumGeometries() == 0) {
writer.write(WKTConstants.EMPTY);
appendEmptyText(outputOrdinates, writer);
}
else {
writer.write("(");
Expand Down Expand Up @@ -850,7 +861,7 @@ private void appendMultiLineStringText(MultiLineString multiLineString, EnumSet<
throws IOException
{
if (multiLineString.getNumGeometries() == 0) {
writer.write(WKTConstants.EMPTY);
appendEmptyText(outputOrdinates, writer);
}
else {
int level2 = level;
Expand Down Expand Up @@ -885,7 +896,7 @@ private void appendMultiPolygonText(
throws IOException
{
if (multiPolygon.getNumGeometries() == 0) {
writer.write(WKTConstants.EMPTY);
appendEmptyText(outputOrdinates, writer);
}
else {
int level2 = level;
Expand Down Expand Up @@ -920,7 +931,7 @@ private void appendGeometryCollectionText(
throws IOException
{
if (geometryCollection.getNumGeometries() == 0) {
writer.write(WKTConstants.EMPTY);
appendEmptyText(outputOrdinates, writer);

@grootstebozewolf grootstebozewolf Sep 3, 2026

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All six instance writer.write(EMPTY) sites now go through the helper (sequence / polygon / multi-point / multi-linestring / multi-polygon / geometry collection). Static toLineString already used " " + EMPTY and is correctly left alone.

}
else {
int level2 = level;
Expand Down
38 changes: 38 additions & 0 deletions modules/core/src/test/java/org/locationtech/jts/io/WKTWriterTest.java
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@grootstebozewolf grootstebozewolf Sep 3, 2026

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Dimensional EMPTY belongs here, not in WKTReadWriteTest (that file already has XY empty round-trips). Leaving Z/M/ZM EMPTY in WKTWriterTest is the right place.

Original file line number Diff line number Diff line change
Expand Up @@ -199,4 +199,42 @@ public void testWktLineStringZM() throws ParseException {
assertEquals(7.0, lineZM.getPointN(1).getCoordinate().getZ());
assertEquals(8.0, lineZM.getPointN(1).getCoordinate().getM());
}

/**
* Nested empty geometries with dimensional markers must keep the marker and
* {@code EMPTY} as separate tokens so that {@link WKTReader} can parse the output.
*/
public void testWriteNestedEmptyDimensionalGeometry() throws ParseException {
WKTReader reader = new WKTReader();
WKTWriter writer4 = new WKTWriter(4);

Geometry geometryZ = reader.read(
"GEOMETRYCOLLECTION Z ("
+ "LINESTRING Z (0 0 1, 1 1 2), "
+ "MULTILINESTRING Z EMPTY)");
String writtenZ = writer4.write(geometryZ);
assertTrue(writtenZ.contains("MULTILINESTRING Z EMPTY"));
assertFalse(writtenZ.contains("ZEMPTY"));
reader.read(writtenZ);
Comment on lines +211 to +218

@grootstebozewolf grootstebozewolf Sep 3, 2026

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Exact #1223 repro for Z (and the M / ZM siblings below), plus a WKTReader round-trip. Enough to lock the reported bug.

contains + assertFalse(...ZEMPTY) is fine. An exact-string assert on the collection would also lock that the non-empty sibling still writes LINESTRING Z(...) with no space before (.

Optional, non-blocking: one top-level POINT Z EMPTY (and maybe POLYGON Z EMPTY) would pin appendSequenceText / appendPolygonText without changing the design. Nested empty LINESTRING / POLYGON take the same helper.


WKTWriter writerM = new WKTWriter(3);
writerM.setOutputOrdinates(Ordinate.createXYM());
Geometry geometryM = reader.read(
"GEOMETRYCOLLECTION M ("
+ "LINESTRING M (0 0 1, 1 1 2), "
+ "MULTILINESTRING M EMPTY)");
String writtenM = writerM.write(geometryM);
assertTrue(writtenM.contains("MULTILINESTRING M EMPTY"));
assertFalse(writtenM.contains("MEMPTY"));
reader.read(writtenM);

Geometry geometryZM = reader.read(
"GEOMETRYCOLLECTION ZM ("
+ "LINESTRING ZM (0 0 1 2, 1 1 2 3), "
+ "MULTILINESTRING ZM EMPTY)");
String writtenZM = writer4.write(geometryZM);
assertTrue(writtenZM.contains("MULTILINESTRING ZM EMPTY"));
assertFalse(writtenZM.contains("ZMEMPTY"));
reader.read(writtenZM);
}
}