Start inferring schema dynamically

Author: simolus3

crates/core/src/schema/mod.rs

@@ -1,5 +1,6 @@
 pub mod inspection;
 mod management;
+mod raw_table;
 mod table_info;
 
 use alloc::{rc::Rc, vec::Vec};

crates/core/src/schema/raw_table.rs

@@ -0,0 +1,46 @@
+use alloc::{
+    string::{String, ToString},
+    vec,
+    vec::Vec,
+};
+use powersync_sqlite_nostd::{Connection, Destructor, ResultCode};
+
+use crate::error::PowerSyncError;
+
+pub struct InferredTableStructure {
+    pub table_name: String,
+    pub has_id_column: bool,
+    pub columns: Vec<String>,
+}
+
+impl InferredTableStructure {
+    pub fn read_from_database(
+        table_name: &str,
+        db: impl Connection,
+    ) -> Result<Option<Self>, PowerSyncError> {
+        let stmt = db.prepare_v2("select name from pragma_table_info(?)")?;
+        stmt.bind_text(1, table_name, Destructor::STATIC)?;
+
+        let mut has_id_column = false;
+        let mut columns = vec![];
+
+        while let ResultCode::ROW = stmt.step()? {
+            let name = stmt.column_text(0)?;
+            if name == "id" {
+                has_id_column = true;
+            } else {
+                columns.push(name.to_string());
+            }
+        }
+
+        if !has_id_column && columns.is_empty() {
+            Ok(None)
+        } else {
+            Ok(Some(Self {
+                table_name: table_name.to_string(),
+                has_id_column,
+                columns,
+            }))
+        }
+    }
+}

crates/core/src/schema/table_info.rs

@@ -21,9 +21,32 @@ pub struct Table {
     pub flags: TableInfoFlags,
 }
 
+#[derive(Deserialize)]
+pub struct RawTableSchema {
+    /// The actual name of the raw table in the local schema.
+    ///
+    /// Currently, this is only used to generate `CREATE TRIGGER` statements for the raw table.
+    #[serde(default)]
+    table_name: Option<String>,
+    #[serde(
+        default,
+        rename = "include_old",
+        deserialize_with = "deserialize_include_old"
+    )]
+    pub diff_include_old: Option<DiffIncludeOld>,
+    #[serde(flatten)]
+    pub flags: TableInfoFlags,
+}
+
 #[derive(Deserialize)]
 pub struct RawTable {
+    /// The [crate::sync::line::OplogEntry::object_type] for which rows should be forwarded to this
+    /// raw table.
+    ///
+    /// This is not necessarily the same as the local name of the raw table.
     pub name: String,
+    #[serde(flatten, default)]
+    pub schema: Option<RawTableSchema>,
     pub put: PendingStatement,
     pub delete: PendingStatement,
     #[serde(default)]