Separate database Result and start generics

4 files changed, 148 insertions, 119 deletions

diff --git a/src/db.zig b/src/db.zig
deleted file mode 100644
index b0aa63a..0000000
--- a/src/db.zig
+++ /dev/null
@@ -1,118 +0,0 @@
-const std = @import("std");
-const assert = std.debug.assert;
-const c = @cImport({
-    @cInclude("duckdb.h");
-});
-
-
-const Result = struct {
-    _res:   c.duckdb_result,
-    _chunk: c.duckdb_data_chunk,
-
-    pub fn init() Result {
-        return .{
-            ._res   = undefined,
-            ._chunk = null
-        };
-    }
-    pub fn deinit(self: *Result) void {
-        c.duckdb_destroy_result(&self._res);
-        c.duckdb_destroy_data_chunk(&self._chunk);
-    }
-
-    /// There's not way to know how many total elements we have, but we can
-    /// know how many we have in the current chunk.
-    fn getCurrentChunkSize(self: Result) usize {
-        if (self._chunk != null) {
-            return 0;
-        }
-        return c.duckdb_data_chunk_get_size(self._chunk);
-    }
-
-    pub fn getColumnCount(self: Result) usize {
-        return c.duckdb_data_chunk_get_column_count(self._chunk);
-    }
-
-    /// This needs to be called repeatedly to obtain the next blocks of
-    /// data. There's no way to know how many elements we'll obtain from
-    /// it.
-    pub fn fetchDataChunk(self: *Result) void{
-        if (self._chunk != null){
-            c.duckdb_destroy_data_chunk(&self._chunk);
-        }
-        self._chunk = c.duckdb_fetch_chunk(self._res);
-    }
-
-    pub fn exausted(self: Result) bool{
-        return self._chunk != null;
-    }
-};
-
-
-const Connection = struct {
-    _conn: c.duckdb_connection,
-
-    pub fn init(db: Self) !Connection {
-        var conn: Connection = undefined;
-        if( c.duckdb_connect(db._db, &conn._conn) == c.DuckDBError ){
-            return error.DuckDBError;
-        }
-        return conn;
-    }
-
-    pub fn deinit(self: *Connection) void {
-        c.duckdb_disconnect(&self._conn);
-    }
-
-    pub fn query(self: *Connection, q: [*c]const u8) !Result{
-        var result = Result.init();
-        const state = c.duckdb_query(self._conn, q, &result._res);
-        if ( state == c.DuckDBError){
-            return error.DuckDBError;
-        }
-        result.fetchDataChunk();
-        return result;
-    }
-};
-
-
-pub const Self = @This();
-
-_db: c.duckdb_database,
-
-pub fn init(file: [*c]const u8) !Self{
-    var db : Self = undefined;
-    if (c.duckdb_open(file, &db._db) == c.DuckDBError) {
-        return error.DuckDBError;
-    }
-    return db;
-}
-
-pub fn deinit(self: *Self) void{
-    c.duckdb_close(&self._db);
-}
-
-pub fn connect(self: Self) !Connection {
-    return Connection.init(self);
-}
-
-test "Open and connect" {
-    var database = try Self.init(":memory:");
-    defer database.deinit();
-    var connection = try database.connect();
-    defer connection.deinit();
-}
-
-test "Query size" {
-    var database = try Self.init(":memory:");
-    defer database.deinit();
-    var connection = try database.connect();
-    defer connection.deinit();
-
-    _ = try connection.query("CREATE TABLE integers (i INTEGER, j INTEGER);");
-    _ = try connection.query("INSERT INTO integers VALUES (3, 4), (5, 6), (7, NULL);");
-    var result = try connection.query("SELECT * FROM integers;");
-    defer result.deinit();
-
-    try std.testing.expect(2 == result.getColumnCount());
-}
diff --git a/src/duckdb/Result.zig b/src/duckdb/Result.zig
new file mode 100644
index 0000000..b49f704
--- /dev/null
+++ b/src/duckdb/Result.zig
@@ -0,0 +1,71 @@
+const std = @import("std");
+const c = @cImport({
+    @cInclude("duckdb.h");
+});
+
+
+pub fn Result(comptime T: type) type{
+
+    return struct {
+        _res:   c.duckdb_result,
+        _chunk: c.duckdb_data_chunk,
+
+        const Self = @This();
+
+        pub fn init(conn : c.duckdb_connection, query: [:0]const u8) !Self {
+            var self : Self = .{
+                ._res   = undefined,
+                ._chunk = null
+            };
+            const state = c.duckdb_query(conn, query, &self._res);
+            if ( state == c.DuckDBError){
+                return error.DuckDBError;
+            }
+            self.fetchDataChunk();
+            return self;
+        }
+        pub fn deinit(self: *Self) void {
+            c.duckdb_destroy_result(&self._res);
+            c.duckdb_destroy_data_chunk(&self._chunk);
+        }
+
+        /// There's not way to know how many total elements we have, but we can
+        /// know how many we have in the current chunk.
+        fn getCurrentChunkSize(self: Self) usize {
+            if (self._chunk != null) {
+                return 0;
+            }
+            return c.duckdb_data_chunk_get_size(self._chunk);
+        }
+
+        pub fn getColumnCount(self: Self) usize {
+            return c.duckdb_data_chunk_get_column_count(self._chunk);
+        }
+
+        /// This needs to be called repeatedly to obtain the next blocks of
+        /// data. There's no way to know how many elements we'll obtain from
+        /// it.
+        fn fetchDataChunk(self: *Self) void{
+            if (self._chunk != null){
+                c.duckdb_destroy_data_chunk(&self._chunk);
+            }
+            self._chunk = c.duckdb_fetch_chunk(self._res);
+        }
+
+        pub fn exausted(self: Self) bool{
+            return self._chunk != null;
+        }
+
+        /// We need some comptime magic to create the output structures from
+        /// the T.
+        pub fn next(self: *Self) T{
+            _ = self;
+            const result: T = undefined;
+            switch (@typeInfo(T)) {
+                .Struct => std.debug.print("GOOOD: ", .{}),
+                else => null,
+            }
+            return result;
+        }
+    };
+}
diff --git a/src/duckdb/db.zig b/src/duckdb/db.zig
new file mode 100644
index 0000000..134a1f4
--- /dev/null
+++ b/src/duckdb/db.zig
@@ -0,0 +1,76 @@
+const std = @import("std");
+const assert = std.debug.assert;
+const c = @cImport({
+    @cInclude("duckdb.h");
+});
+const Result = @import("Result.zig").Result;
+
+
+const Connection = struct {
+    _conn: c.duckdb_connection,
+
+    pub fn init(db: Database) !Connection {
+        var conn: Connection = undefined;
+        if( c.duckdb_connect(db._db, &conn._conn) == c.DuckDBError ){
+            return error.DuckDBError;
+        }
+        return conn;
+    }
+
+    pub fn deinit(self: *Connection) void {
+        c.duckdb_disconnect(&self._conn);
+    }
+
+    pub fn query(self: *Connection, q: [:0]const u8, comptime res_type: type)
+        !Result(res_type) {
+        return try Result(res_type).init(self._conn, q);
+    }
+};
+
+
+pub const Database = @This();
+
+_db: c.duckdb_database,
+
+pub fn init(file: [*c]const u8) !Database{
+    var db : Database = undefined;
+    if (c.duckdb_open(file, &db._db) == c.DuckDBError) {
+        return error.DuckDBError;
+    }
+    return db;
+}
+
+pub fn deinit(self: *Database) void{
+    c.duckdb_close(&self._db);
+}
+
+pub fn connect(self: Database) !Connection {
+    return Connection.init(self);
+}
+
+test "Open and connect" {
+    var database = try Database.init(":memory:");
+    defer database.deinit();
+    var connection = try database.connect();
+    defer connection.deinit();
+}
+
+test "Query size" {
+    var database = try Database.init(":memory:");
+    defer database.deinit();
+    var connection = try database.connect();
+    defer connection.deinit();
+
+    const s : type = comptime struct {
+        primer: u8,
+        segund: u8
+    };
+
+    _ = try connection.query("CREATE TABLE integers (i INTEGER, j INTEGER);", void);
+    _ = try connection.query("INSERT INTO integers VALUES (3, 4), (5, 6), (7, NULL);", void);
+    var result = try connection.query("SELECT * FROM integers;", s);
+    _ = result.next();
+    defer result.deinit();
+
+    try std.testing.expect(2 == result.getColumnCount());
+}
diff --git a/src/main.zig b/src/main.zig
index 14e1810..d970b68 100644
--- a/src/main.zig
+++ b/src/main.zig
@@ -1,5 +1,5 @@
 const std = @import("std");
-pub const Db  = @import("./db.zig");
+pub const Db  = @import("./duckdb/db.zig");
 
 pub fn main() !void {
     var database = try Db.init(":memory:");