twalthr commented on a change in pull request #8929: [FLINK-13028][table] Move
expression resolver to flink-table-api-java
URL: https://github.com/apache/flink/pull/8929#discussion_r299330024
##########
File path:
flink-table/flink-table-api-java/src/main/java/org/apache/flink/table/expressions/resolver/rules/ResolveCallByArgumentsRule.java
##########
@@ -38,75 +40,103 @@
import org.apache.flink.table.types.inference.TypeStrategies;
import org.apache.flink.util.Preconditions;
-import java.util.ArrayList;
+import java.util.Collections;
import java.util.List;
import java.util.Optional;
import java.util.stream.Collectors;
import java.util.stream.IntStream;
+import static java.util.Collections.singletonList;
+import static
org.apache.flink.table.expressions.utils.ApiExpressionUtils.valueLiteral;
+import static
org.apache.flink.table.types.utils.TypeConversions.fromDataTypeToLegacyInfo;
+import static
org.apache.flink.table.types.utils.TypeConversions.fromLegacyInfoToDataType;
+
/**
* This rule checks if a {@link UnresolvedCallExpression} can work with the
given arguments and infers
* the output data type. All function calls are resolved {@link
CallExpression} after applying this
- * rule except for the special case of {@link
BuiltInFunctionDefinitions#FLATTEN}.
+ * rule.
+ *
+ * <p>This rule also resolves {@code flatten()} calls on composite types.
*
* <p>If the call expects different types of arguments, but the given
arguments have types that can
* be casted, a {@link BuiltInFunctionDefinitions#CAST} expression is inserted.
- *
- * @see ResolveFlattenCallRule
*/
@Internal
final class ResolveCallByArgumentsRule implements ResolverRule {
@Override
public List<Expression> apply(List<Expression> expression,
ResolutionContext context) {
return expression.stream()
- .map(expr -> expr.accept(new
CallArgumentsCastingVisitor(context)))
+ .flatMap(expr -> expr.accept(new
ResolvingCallVisitor(context)).stream())
.collect(Collectors.toList());
}
- private class CallArgumentsCastingVisitor extends
RuleExpressionVisitor<Expression> {
+ //
--------------------------------------------------------------------------------------------
+
+ private class ResolvingCallVisitor extends
RuleExpressionVisitor<List<ResolvedExpression>> {
- CallArgumentsCastingVisitor(ResolutionContext context) {
+ ResolvingCallVisitor(ResolutionContext context) {
super(context);
}
@Override
- public Expression visit(UnresolvedCallExpression
unresolvedCall) {
+ public List<ResolvedExpression> visit(UnresolvedCallExpression
unresolvedCall) {
final List<ResolvedExpression> resolvedArgs =
unresolvedCall.getChildren().stream()
- .map(c -> c.accept(this))
- .map(e -> {
- // special case: FLATTEN
- // a call chain
`myFunc().flatten().flatten()` is not allowed
- if (e instanceof
UnresolvedCallExpression &&
-
((UnresolvedCallExpression) e).getFunctionDefinition() ==
BuiltInFunctionDefinitions.FLATTEN) {
- throw new
ValidationException("Consecutive flattening calls are not allowed.");
- }
- if (e instanceof ResolvedExpression) {
- return (ResolvedExpression) e;
- }
- throw new TableException("Unexpected
unresolved expression: " + e);
- })
+ .flatMap(c -> c.accept(this).stream())
.collect(Collectors.toList());
- // FLATTEN is a special case and the only call that
remains unresolved after this rule
- // it will be resolved by ResolveFlattenCallRule
if (unresolvedCall.getFunctionDefinition() ==
BuiltInFunctionDefinitions.FLATTEN) {
- return unresolvedCall.replaceArgs(new
ArrayList<>(resolvedArgs));
+ return executeFlatten(resolvedArgs);
}
if (unresolvedCall.getFunctionDefinition() instanceof
BuiltInFunctionDefinition) {
final BuiltInFunctionDefinition definition =
(BuiltInFunctionDefinition)
unresolvedCall.getFunctionDefinition();
if
(definition.getTypeInference().getOutputTypeStrategy() !=
TypeStrategies.MISSING) {
- return runTypeInference(
- unresolvedCall,
- definition.getTypeInference(),
- resolvedArgs);
+ return Collections.singletonList(
+ runTypeInference(
+ unresolvedCall,
+
definition.getTypeInference(),
+ resolvedArgs));
}
}
- return runLegacyTypeInference(unresolvedCall,
resolvedArgs);
+ return Collections.singletonList(
+ runLegacyTypeInference(unresolvedCall,
resolvedArgs));
+ }
+
+ @Override
+ protected List<ResolvedExpression> defaultMethod(Expression
expression) {
+ if (expression instanceof ResolvedExpression) {
+ return
Collections.singletonList((ResolvedExpression) expression);
+ }
+ throw new TableException("Unexpected unresolved
expression: " + expression);
+ }
+
+ private List<ResolvedExpression>
executeFlatten(List<ResolvedExpression> args) {
+ if (args.size() != 1) {
+ throw new ValidationException("Invalid number
of arguments for flattening.");
+ }
+ final ResolvedExpression composite = args.get(0);
+ final TypeInformation<?> resultType =
fromDataTypeToLegacyInfo(composite.getOutputDataType());
Review comment:
Yes you are right. I will leave a TODO there. We will need to touch this
part of code again soon.
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