Define some helper traits to reduce duplication

core/types.rs

@@ -82,7 +82,6 @@ impl Text {
             subtype: TextSubtype::Text,
         }
     }
-
     #[cfg(feature = "json")]
     pub fn json(value: String) -> Self {
         Self {
@@ -96,6 +95,73 @@ impl Text {
     }
 }
 
+pub trait Extendable<T> {
+    fn maybe_extend(&mut self, other: &T) -> bool;
+}
+
+impl<T: AnyText> Extendable<T> for Text {
+    fn maybe_extend(&mut self, other: &T) -> bool {
+        if self.value.capacity() >= other.as_ref().len() {
+            self.value.clear();
+            self.value.extend_from_slice(other.as_ref().as_bytes());
+            self.subtype = other.subtype();
+            true
+        } else {
+            false
+        }
+    }
+}
+
+impl<T: AnyBlob> Extendable<T> for Vec<u8> {
+    fn maybe_extend(&mut self, other: &T) -> bool {
+        if self.capacity() >= other.as_slice().len() {
+            self.clear();
+            self.extend_from_slice(other.as_slice());
+            true
+        } else {
+            false
+        }
+    }
+}
+
+pub trait AnyText: AsRef<str> {
+    fn subtype(&self) -> TextSubtype;
+}
+
+impl AsRef<str> for TextRef {
+    fn as_ref(&self) -> &str {
+        self.as_str()
+    }
+}
+
+impl AnyText for Text {
+    fn subtype(&self) -> TextSubtype {
+        self.subtype
+    }
+}
+
+impl AnyText for TextRef {
+    fn subtype(&self) -> TextSubtype {
+        self.subtype
+    }
+}
+
+pub trait AnyBlob {
+    fn as_slice(&self) -> &[u8];
+}
+
+impl AnyBlob for RawSlice {
+    fn as_slice(&self) -> &[u8] {
+        self.to_slice()
+    }
+}
+
+impl AnyBlob for Vec<u8> {
+    fn as_slice(&self) -> &[u8] {
+        self.as_slice()
+    }
+}
+
 impl AsRef<str> for Text {
     fn as_ref(&self) -> &str {
         self.as_str()

core/vdbe/execute.rs

@@ -10,8 +10,8 @@ use crate::storage::wal::DummyWAL;
 use crate::storage::{self, header_accessor};
 use crate::translate::collate::CollationSeq;
 use crate::types::{
-    compare_immutable, compare_records_generic, ImmutableRecord, RawSlice, SeekResult, Text,
-    TextRef, TextSubtype,
+    compare_immutable, compare_records_generic, Extendable, ImmutableRecord, RawSlice, SeekResult,
+    Text, TextRef, TextSubtype,
 };
 use crate::util::normalize_ident;
 use crate::vdbe::insn::InsertFlags;
@@ -1595,23 +1595,13 @@ pub fn op_column(
                 };
                 match (default, &mut state.registers[*dest]) {
                     (Value::Text(new_text), Register::Value(Value::Text(existing_text))) => {
-                        let new_text_str = new_text.as_str();
-                        if existing_text.value.capacity() >= new_text_str.len() {
-                            existing_text.value.clear();
-                            existing_text
-                                .value
-                                .extend_from_slice(new_text_str.as_bytes());
-                            existing_text.subtype = new_text.subtype;
-                        } else {
+                        if !existing_text.maybe_extend(new_text) {
                             state.registers[*dest] =
-                                Register::Value(Value::Text(Text::new(new_text_str)));
+                                Register::Value(Value::Text(Text::new(new_text.as_str())));
                         }
                     }
                     (Value::Blob(new_blob), Register::Value(Value::Blob(existing_blob))) => {
-                        if existing_blob.capacity() >= new_blob.len() {
-                            existing_blob.clear();
-                            existing_blob.extend_from_slice(new_blob);
-                        } else {
+                        if !existing_blob.maybe_extend(new_blob) {
                             state.registers[*dest] =
                                 Register::Value(Value::Blob(new_blob.to_vec()));
                         }
@@ -1627,26 +1617,15 @@ pub fn op_column(
             // Try to reuse the registers when allocation is not needed.
             match (&value, &mut state.registers[*dest]) {
                 (RefValue::Text(new_text), Register::Value(Value::Text(existing_text))) => {
-                    let new_text_str = new_text.as_str();
-                    if existing_text.value.capacity() >= new_text_str.len() {
-                        existing_text.value.clear();
-                        existing_text
-                            .value
-                            .extend_from_slice(new_text_str.as_bytes());
-                        existing_text.subtype = new_text.subtype;
-                    } else {
+                    if !existing_text.maybe_extend(new_text) {
                         state.registers[*dest] =
-                            Register::Value(Value::Text(Text::new(new_text_str)));
+                            Register::Value(Value::Text(Text::new(new_text.as_str())));
                     }
                 }
                 (RefValue::Blob(new_blob), Register::Value(Value::Blob(existing_blob))) => {
-                    let new_blob_slice = new_blob.to_slice();
-                    if existing_blob.capacity() >= new_blob_slice.len() {
-                        existing_blob.clear();
-                        existing_blob.extend_from_slice(new_blob_slice);
-                    } else {
+                    if !existing_blob.maybe_extend(new_blob) {
                         state.registers[*dest] =
-                            Register::Value(Value::Blob(new_blob_slice.to_vec()));
+                            Register::Value(Value::Blob(new_blob.to_slice().to_vec()));
                     }
                 }
                 _ => {