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Pre-size flattened parser sequences #1465

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Pre-size flattened parser sequences #1465

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41 changes: 23 additions & 18 deletions src/main/java/com/fasterxml/jackson/core/util/JsonParserSequence.java
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Original file line number Diff line number Diff line change
Expand Up @@ -93,17 +93,9 @@ public static JsonParserSequence createFlattened(boolean checkForExistingToken,
return new JsonParserSequence(checkForExistingToken,
new JsonParser[] { first, second });
}
ArrayList<JsonParser> p = new ArrayList<>();
if (first instanceof JsonParserSequence) {
((JsonParserSequence) first).addFlattenedActiveParsers(p);
} else {
p.add(first);
}
if (second instanceof JsonParserSequence) {
((JsonParserSequence) second).addFlattenedActiveParsers(p);
} else {
p.add(second);
}
ArrayList<JsonParser> p = new ArrayList<>(8);
flattenParsers(first, p);
flattenParsers(second, p);
return new JsonParserSequence(checkForExistingToken,
p.toArray(new JsonParser[p.size()]));
}
Expand All @@ -116,13 +108,26 @@ public static JsonParserSequence createFlattened(JsonParser first, JsonParser se
@SuppressWarnings("resource")
protected void addFlattenedActiveParsers(List<JsonParser> listToAddIn)
{
for (int i = _nextParserIndex-1, len = _parsers.length; i < len; ++i) {
JsonParser p = _parsers[i];
if (p instanceof JsonParserSequence) {
((JsonParserSequence) p).addFlattenedActiveParsers(listToAddIn);
} else {
listToAddIn.add(p);
}
int i = _nextParserIndex-1;
int len = _parsers.length;
expandToAdd(listToAddIn, len - i);
for (; i < len; ++i) {
flattenParsers(_parsers[i], listToAddIn);
}
}

private static void flattenParsers(JsonParser parser, List<JsonParser> p) {
if (parser instanceof JsonParserSequence) {
((JsonParserSequence) parser).addFlattenedActiveParsers(p);
} else {
p.add(parser);
}
}

private static void expandToAdd(List<?> list, int additionalCapacity) {
if (additionalCapacity > 0 && list instanceof ArrayList<?>) {
int newCapacity = list.size() + additionalCapacity;
((ArrayList<?>) list).ensureCapacity(newCapacity);
}
}

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