Scaffolding for in-extension filtering

Supports IS NULL and IS NOT NULL checks

parquet/parquet_filter.cc

@@ -0,0 +1,47 @@
+#include "parquet_filter.h"
+
+Constraint::Constraint(
+  int column,
+  ConstraintOperator op,
+  ValueType type,
+  bool boolValue,
+  uintptr_t intValue,
+  double doubleValue,
+  std::vector<unsigned char> blobValue
+) {
+  this->column = column;
+  this->op = op;
+  this->type = type;
+  this->boolValue = boolValue;
+  this->intValue = intValue;
+  this->doubleValue = doubleValue;
+  this->blobValue = blobValue;
+}
+
+int Constraint::getColumn() {
+  return column;
+}
+
+ConstraintOperator Constraint::getOperator() {
+  return op;
+}
+
+ValueType Constraint::getType() {
+  return type;
+}
+
+bool Constraint::getBool() {
+  return boolValue;
+}
+
+uintptr_t Constraint::getInt() {
+  return intValue;
+}
+
+double Constraint::getDouble() {
+  return doubleValue;
+}
+
+std::vector<unsigned char> Constraint::getBytes() {
+  return blobValue;
+}