add a writer that never skips empty or missing strings

2 files changed, 27 insertions, 3 deletions

diff --git a/searchsummary/src/vespa/searchsummary/docsummary/attribute_field_writer.cpp b/searchsummary/src/vespa/searchsummary/docsummary/attribute_field_writer.cpp
index 99c5d8b7f30..cf07d887328 100644
--- a/searchsummary/src/vespa/searchsummary/docsummary/attribute_field_writer.cpp
+++ b/searchsummary/src/vespa/searchsummary/docsummary/attribute_field_writer.cpp
@@ -46,6 +46,15 @@ public:
     void print(uint32_t idx, Cursor &cursor) override;
 };
 
+class WriteStringFieldNeverSkip : public WriteField<search::attribute::ConstCharContent>
+{
+public:
+    WriteStringFieldNeverSkip(vespalib::Memory fieldName,
+                             const IAttributeVector &attr)
+      : WriteField(fieldName, attr) {}
+    ~WriteStringFieldNeverSkip() override {}
+    void print(uint32_t idx, Cursor &cursor) override;
+};
 
 class WriteFloatField : public WriteField<search::attribute::FloatContent>
 {
@@ -104,6 +113,17 @@ WriteStringField::print(uint32_t idx, Cursor &cursor)
     }
 }
 
+void
+WriteStringFieldNeverSkip::print(uint32_t idx, Cursor &cursor)
+{
+    if (idx < _size) {
+        const char *s = _content[idx];
+        cursor.setString(_fieldName, vespalib::Memory(s));
+    } else {
+        cursor.setString(_fieldName, vespalib::Memory(""));
+    }
+}
+
 WriteFloatField::WriteFloatField(vespalib::Memory fieldName,
                                  const IAttributeVector &attr)
     : WriteField(fieldName, attr)
@@ -147,7 +167,7 @@ WriteIntField::print(uint32_t idx, Cursor &cursor)
 }
 
 std::unique_ptr<AttributeFieldWriter>
-AttributeFieldWriter::create(vespalib::Memory fieldName, const IAttributeVector &attr)
+AttributeFieldWriter::create(vespalib::Memory fieldName, const IAttributeVector &attr, bool no_empty_strings)
 {
     switch (attr.getBasicType()) {
     case BasicType::INT8:
@@ -162,7 +182,11 @@ AttributeFieldWriter::create(vespalib::Memory fieldName, const IAttributeVector
     case BasicType::DOUBLE:
         return std::make_unique<WriteFloatField>(fieldName, attr);
     case BasicType::STRING:
-        return std::make_unique<WriteStringField>(fieldName, attr);
+        if (no_empty_strings) {
+            return std::make_unique<WriteStringFieldNeverSkip>(fieldName, attr);
+        } else {
+            return std::make_unique<WriteStringField>(fieldName, attr);
+        }
     default:
         assert(false);
         abort();
diff --git a/searchsummary/src/vespa/searchsummary/docsummary/attribute_field_writer.h b/searchsummary/src/vespa/searchsummary/docsummary/attribute_field_writer.h
index 3fed6edb1b5..d0f1487b76a 100644
--- a/searchsummary/src/vespa/searchsummary/docsummary/attribute_field_writer.h
+++ b/searchsummary/src/vespa/searchsummary/docsummary/attribute_field_writer.h
@@ -27,7 +27,7 @@ public:
     virtual ~AttributeFieldWriter();
     virtual void fetch(uint32_t docId) = 0;
     virtual void print(uint32_t idx, vespalib::slime::Cursor &cursor) = 0;
-    static std::unique_ptr<AttributeFieldWriter> create(vespalib::Memory fieldName, const search::attribute::IAttributeVector &attr);
+    static std::unique_ptr<AttributeFieldWriter> create(vespalib::Memory fieldName, const search::attribute::IAttributeVector &attr, bool no_empty_strings = false);
     uint32_t size() const { return _size; }
 };