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Replace nested Stream.concat with direct iteration in expression merging #6725

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Replace nested Stream.concat with direct iteration in expression merging #6725

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d6916da
Replace nested Stream.concat with direct iteration in expression merging
RanVaknin Feb 10, 2026
1e70ec5
Refactor merge function to only do one map lookup since put returns t…
RanVaknin Feb 10, 2026
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81 changes: 59 additions & 22 deletions ...a/software/amazon/awssdk/enhanced/dynamodb/internal/update/UpdateExpressionConverter.java
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Original file line number Diff line number Diff line change
Expand Up @@ -17,6 +17,7 @@

import java.util.ArrayList;
import java.util.Collections;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
import java.util.stream.Collectors;
Expand Down Expand Up @@ -114,7 +115,7 @@ private static List<String> groupExpressions(UpdateExpression expression) {
List<String> groupExpressions = new ArrayList<>();
if (!expression.setActions().isEmpty()) {
groupExpressions.add(SET + expression.setActions().stream()
.map(a -> String.format("%s = %s", a.path(), a.value()))
.map(a -> a.path() + " = " + a.value())
.collect(Collectors.joining(ACTION_SEPARATOR)));
}
if (!expression.removeActions().isEmpty()) {
Expand All @@ -124,42 +125,78 @@ private static List<String> groupExpressions(UpdateExpression expression) {
}
if (!expression.deleteActions().isEmpty()) {
groupExpressions.add(DELETE + expression.deleteActions().stream()
.map(a -> String.format("%s %s", a.path(), a.value()))
.map(a -> a.path() + " " + a.value())
.collect(Collectors.joining(ACTION_SEPARATOR)));
}
if (!expression.addActions().isEmpty()) {
groupExpressions.add(ADD + expression.addActions().stream()
.map(a -> String.format("%s %s", a.path(), a.value()))
.map(a -> a.path() + " " + a.value())
.collect(Collectors.joining(ACTION_SEPARATOR)));
}
return groupExpressions;
}

private static Stream<Map<String, String>> streamOfExpressionNames(UpdateExpression expression) {
return Stream.concat(expression.setActions().stream().map(SetAction::expressionNames),
Stream.concat(expression.removeActions().stream().map(RemoveAction::expressionNames),
Stream.concat(expression.deleteActions().stream()
.map(DeleteAction::expressionNames),
expression.addActions().stream()
.map(AddAction::expressionNames))));
private static Map<String, AttributeValue> mergeExpressionValues(UpdateExpression expression) {
Map<String, AttributeValue> merged = new HashMap<>();

for (SetAction action : expression.setActions()) {
mergeValuesInto(merged, action.expressionValues());
}
for (DeleteAction action : expression.deleteActions()) {
mergeValuesInto(merged, action.expressionValues());
}
for (AddAction action : expression.addActions()) {
mergeValuesInto(merged, action.expressionValues());
}

return merged.isEmpty() ? Collections.emptyMap() : Collections.unmodifiableMap(merged);
}

private static Map<String, AttributeValue> mergeExpressionValues(UpdateExpression expression) {
return streamOfExpressionValues(expression)
.reduce(Expression::joinValues)
.orElseGet(Collections::emptyMap);
private static Map<String, String> mergeExpressionNames(UpdateExpression expression) {
Map<String, String> merged = new HashMap<>();

for (SetAction action : expression.setActions()) {
mergeNamesInto(merged, action.expressionNames());
}
for (RemoveAction action : expression.removeActions()) {
mergeNamesInto(merged, action.expressionNames());
}
for (DeleteAction action : expression.deleteActions()) {
mergeNamesInto(merged, action.expressionNames());
}
for (AddAction action : expression.addActions()) {
mergeNamesInto(merged, action.expressionNames());
}

return merged.isEmpty() ? Collections.emptyMap() : Collections.unmodifiableMap(merged);
}

private static Stream<Map<String, AttributeValue>> streamOfExpressionValues(UpdateExpression expression) {
return Stream.concat(expression.setActions().stream().map(SetAction::expressionValues),
Stream.concat(expression.deleteActions().stream().map(DeleteAction::expressionValues),
expression.addActions().stream().map(AddAction::expressionValues)));
private static void mergeNamesInto(Map<String, String> target, Map<String, String> source) {
if (source == null || source.isEmpty()) {
return;
}
source.forEach((key, value) -> {
String oldValue = target.put(key, value);
if (oldValue != null && !oldValue.equals(value)) {
throw new IllegalArgumentException(
String.format("Attempt to coalesce two expressions with conflicting expression names. "
+ "Expression name key = '%s'", key));
}
});
}

private static Map<String, String> mergeExpressionNames(UpdateExpression expression) {
return streamOfExpressionNames(expression)
.reduce(Expression::joinNames)
.orElseGet(Collections::emptyMap);
private static void mergeValuesInto(Map<String, AttributeValue> target, Map<String, AttributeValue> source) {
if (source == null || source.isEmpty()) {
return;
}
source.forEach((key, value) -> {
AttributeValue oldValue = target.put(key, value);
if (oldValue != null && !oldValue.equals(value)) {
throw new IllegalArgumentException(
String.format("Attempt to coalesce two expressions with conflicting expression values. "
+ "Expression value key = '%s'", key));
}
});
}

private static List<String> listPathsWithoutTokens(UpdateExpression expression) {
Expand Down
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