rdblue commented on code in PR #4938:
URL: https://github.com/apache/iceberg/pull/4938#discussion_r895214802
##########
api/src/main/java/org/apache/iceberg/expressions/Binder.java:
##########
@@ -96,7 +96,15 @@ public static Set<Integer> boundReferences(StructType
struct, List<Expression> e
}
ReferenceVisitor visitor = new ReferenceVisitor();
for (Expression expr : exprs) {
- ExpressionVisitors.visit(bind(struct, expr, caseSensitive), visitor);
+ try {
+ ExpressionVisitors.visit(bind(struct, expr, caseSensitive), visitor);
+ } catch (IllegalStateException e) {
+ if (e.getMessage().contains("Found already bound predicate")) {
Review Comment:
We shouldn't rely on exception messages like this.
I think instead we should just add a utility to detect whether an expression
is bound. Here's an implementation:
```java
/**
* Returns whether an expression is bound.
* <p>
* An expression is bound if all of its predicates are bound.
*
* @param expr an {@link Expression}
* @return true if the expression is bound
* @throws IllegalArgumentException if the expression has both bound and
unbound predicates.
*/
public static boolean isBound(Expression expr) {
Boolean isBound = ExpressionVisitors.visit(expr, new IsBoundVisitor());
return isBound != null ? isBound : false; // assume unbound if
undetermined
}
private static class IsBoundVisitor extends
ExpressionVisitors.ExpressionVisitor<Boolean> {
@Override
public Boolean not(Boolean result) {
return result;
}
@Override
public Boolean and(Boolean leftResult, Boolean rightResult) {
return combineResults(leftResult, rightResult);
}
@Override
public Boolean or(Boolean leftResult, Boolean rightResult) {
return combineResults(leftResult, rightResult);
}
@Override
public <T> Boolean predicate(BoundPredicate<T> pred) {
return true;
}
@Override
public <T> Boolean predicate(UnboundPredicate<T> pred) {
return false;
}
private Boolean combineResults(Boolean isLeftBound, Boolean
isRightBound) {
if (isLeftBound != null) {
Preconditions.checkArgument(isRightBound == null ||
isLeftBound.equals(isRightBound),
"Found partially bound expression");
return isLeftBound;
} else {
return isRightBound;
}
}
}
```
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