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// Copyright Vespa.ai. Licensed under the terms of the Apache 2.0 license. See LICENSE in the project root.
package com.yahoo.search.yql;
import com.google.common.collect.Maps;
import com.google.common.collect.Sets;
import java.util.ArrayList;
import java.util.List;
import java.util.Map;
import java.util.Set;
class ProjectionBuilder {
private final Map<String, OperatorNode<ExpressionOperator>> fields = Maps.newLinkedHashMap();
private final Set<String> aliasNames = Sets.newHashSet();
public void addField(String name, OperatorNode<ExpressionOperator> expr) {
String aliasName = name;
if (name == null) {
name = assignName(expr);
}
if (fields.containsKey(name)) {
throw new ProgramCompileException(expr.getLocation(), "Field alias '%s' already defined", name);
}
fields.put(name, expr);
if (aliasName != null) {
// Store use
aliasNames.add(aliasName);
}
}
public boolean isAlias(String name) {
return aliasNames.contains(name);
}
private String assignName(OperatorNode<ExpressionOperator> expr) {
String baseName = switch (expr.getOperator()) {
case PROPREF -> (String) expr.getArgument(1);
case READ_RECORD -> (String) expr.getArgument(0);
case READ_FIELD -> (String) expr.getArgument(1);
case VARREF -> (String) expr.getArgument(0);
default -> "expr";
// fall through, leaving baseName alone
};
int c = 0;
String candidate = baseName;
while (fields.containsKey(candidate)) {
candidate = baseName + (++c);
}
return candidate;
}
public OperatorNode<SequenceOperator> make(OperatorNode<SequenceOperator> target) {
List<OperatorNode<ProjectOperator>> lst = new ArrayList<>();
for (Map.Entry<String, OperatorNode<ExpressionOperator>> e : fields.entrySet()) {
if (e.getKey().startsWith("*")) {
lst.add(OperatorNode.create(ProjectOperator.MERGE_RECORD, e.getValue().getArgument(0)));
} else if (e.getValue().getOperator() == ExpressionOperator.READ_RECORD) {
lst.add(OperatorNode.create(ProjectOperator.RECORD, e.getValue(), e.getKey()));
} else {
lst.add(OperatorNode.create(ProjectOperator.FIELD, e.getValue(), e.getKey()));
}
}
return OperatorNode.create(SequenceOperator.PROJECT, target, List.copyOf(lst));
}
}
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