libsql: Add Statement::column_count() API (tursodatabase#2067)

Author: penberg

libsql/src/hrana/hyper.rs

@@ -234,6 +234,10 @@ impl crate::statement::Stmt for crate::hrana::Statement<HttpSender> {
         Some(&named_param.name)
     }
 
+    fn column_count(&self) -> usize {
+        self.cols.len()
+    }
+
     fn columns(&self) -> Vec<crate::Column> {
         //FIXME: there are several blockers here:
         // 1. We cannot know the column types before sending a query, so this method will never return results right

libsql/src/local/impls.rs

@@ -145,6 +145,10 @@ impl Stmt for LibsqlStmt {
         self.0.parameter_name(idx)
     }
 
+    fn column_count(&self) -> usize {
+        self.0.column_count()
+    }
+
     fn columns(&self) -> Vec<Column> {
         self.0.columns()
     }

libsql/src/replication/connection.rs

@@ -779,6 +779,16 @@ impl Stmt for RemoteStatement {
         }
     }
 
+    fn column_count(&self) -> usize {
+        if let Some(stmt) = self.local_statement.as_ref() {
+            return stmt.column_count();
+        }
+        match self.metas.first() {
+            Some(meta) => meta.columns.len(),
+            None => 0,
+        }
+    }
+
     fn columns(&self) -> Vec<Column> {
         if let Some(stmt) = self.local_statement.as_ref() {
             return stmt.columns();

libsql/src/statement.rs

@@ -22,6 +22,8 @@ pub(crate) trait Stmt {
 
     fn parameter_name(&self, idx: i32) -> Option<&str>;
 
+    fn column_count(&self) -> usize;
+
     fn columns(&self) -> Vec<Column>;
 }
 
@@ -95,6 +97,11 @@ impl Statement {
         self.inner.parameter_name(idx)
     }
 
+    /// Fetch the number of columns for the prepared statement.
+    pub fn column_count(&self) -> usize {
+        self.inner.column_count()
+    }
+
     /// Fetch the list of columns for the prepared statement.
     pub fn columns(&self) -> Vec<Column> {
         self.inner.columns()

libsql/src/sync/statement.rs

@@ -56,6 +56,10 @@ impl Stmt for SyncedStatement {
         self.inner.parameter_name(idx)
     }
 
+    fn column_count(&self) -> usize {
+        self.inner.column_count()
+    }
+
     fn columns(&self) -> Vec<Column> {
         self.inner.columns()
     }