From f073ffa4adb41033ebe1b019734f1f66ef46b58d Mon Sep 17 00:00:00 2001
From: Alexander Medvednikov <alexander@vlang.io>
Date: Sat, 27 Jun 2020 16:19:12 +0200
Subject: [PATCH] orm: limit

---
 vlib/orm/orm_test.v |  6 ++++++
 vlib/v/ast/ast.v    | 50 +++++++++++++++++++++++----------------------
 vlib/v/gen/sql.v    |  9 ++++++--
 vlib/v/parser/sql.v |  8 +++++++-
 4 files changed, 46 insertions(+), 27 deletions(-)

diff --git a/vlib/orm/orm_test.v b/vlib/orm/orm_test.v
index b0078385ce..967ec397ac 100644
--- a/vlib/orm/orm_test.v
+++ b/vlib/orm/orm_test.v
@@ -168,6 +168,12 @@ fn test_orm_sqlite() {
 	}
 	assert no_user.name == '' // TODO optional
 	assert no_user.age == 0
+	//
+	two_users := sql db {
+		select from User limit 2
+	}
+	assert two_users.len == 2
+	assert two_users[0].id > 0
 }
 
 struct User {
diff --git a/vlib/v/ast/ast.v b/vlib/v/ast/ast.v
index 89b1f5a7a9..e4f531bf6b 100644
--- a/vlib/v/ast/ast.v
+++ b/vlib/v/ast/ast.v
@@ -106,7 +106,7 @@ pub:
 	field_name string
 pub mut:
 	expr_type  table.Type // type of `Foo` in `Foo.bar`
-	typ  table.Type // type of the entire thing (`Foo.bar`)
+	typ        table.Type // type of the entire thing (`Foo.bar`)
 }
 
 // module declaration
@@ -211,10 +211,10 @@ pub:
 
 pub struct AnonFn {
 pub:
-	decl FnDecl
+	decl      FnDecl
 	is_called bool
 pub mut:
-	typ  table.Type
+	typ       table.Type
 }
 
 pub struct FnDecl {
@@ -809,7 +809,6 @@ pub enum SqlExprKind {
 	update
 }
 */
-
 pub enum SqlStmtKind {
 	insert
 	update
@@ -818,32 +817,36 @@ pub enum SqlStmtKind {
 
 pub struct SqlStmt {
 pub:
-	kind SqlStmtKind
-	db_expr    Expr // `db` in `sql db {`
+	kind            SqlStmtKind
+	db_expr         Expr // `db` in `sql db {`
 	object_var_name string // `user`
 	table_type      table.Type
-	pos token.Position
-	where_expr Expr
-	updated_columns []string //for `update set x=y`
-	update_exprs []Expr//for `update`
+	pos             token.Position
+	where_expr      Expr
+	updated_columns []string // for `update set x=y`
+	update_exprs    []Expr // for `update`
 pub mut:
-	table_name string
-	fields     []table.Field
+	table_name      string
+	fields          []table.Field
 }
 
 pub struct SqlExpr {
 pub:
-	typ        table.Type
-	is_count   bool
-	db_expr    Expr // `db` in `sql db {`
-	where_expr Expr
-	has_where  bool
-	is_array   bool
-	table_type table.Type
-	pos token.Position
+	typ         table.Type
+	is_count    bool
+	db_expr     Expr // `db` in `sql db {`
+	where_expr  Expr
+	has_where   bool
+	has_offset  bool
+	offset_expr Expr
+	is_array    bool
+	table_type  table.Type
+	pos         token.Position
+	has_limit   bool
+	limit_expr  Expr
 pub mut:
-	table_name string
-	fields     []table.Field
+	table_name  string
+	fields      []table.Field
 }
 
 [inline]
@@ -898,8 +901,7 @@ pub fn (expr Expr) position() token.Position {
 		InfixExpr {
 			left_pos := expr.left.position()
 			right_pos := expr.right.position()
-			if left_pos.pos == 0 ||
-				right_pos.pos == 0 {
+			if left_pos.pos == 0 || right_pos.pos == 0 {
 				return expr.pos
 			}
 			return token.Position{
diff --git a/vlib/v/gen/sql.v b/vlib/v/gen/sql.v
index c23f6c41cf..9bdce67866 100644
--- a/vlib/v/gen/sql.v
+++ b/vlib/v/gen/sql.v
@@ -131,7 +131,12 @@ fn (mut g Gen) sql_select_expr(node ast.SqlExpr) {
 	if node.has_where && node.where_expr is ast.InfixExpr {
 		g.expr_to_sql(node.where_expr)
 	}
-	g.writeln(' order by id"));')
+	g.write(' order by id ')
+	if node.has_limit {
+		g.write(' limit ')
+		g.expr_to_sql(node.limit_expr)
+	}
+	g.writeln('"));')
 	// Dump all sql parameters generated by our custom expr handler
 	binds := g.sql_buf.str()
 	g.sql_buf = strings.new_builder(100)
@@ -182,7 +187,7 @@ fn (mut g Gen) sql_select_expr(node ast.SqlExpr) {
 			g.writeln('\tif (_step_res$tmp == SQLITE_ROW) ;') // another row
 			g.writeln('\telse if (_step_res$tmp != SQLITE_OK) break;')
 		} else {
-			g.writeln('printf("RES: %d\\n", _step_res$tmp) ;')
+			// g.writeln('printf("RES: %d\\n", _step_res$tmp) ;')
 			g.writeln('\tif (_step_res$tmp == SQLITE_OK || _step_res$tmp == SQLITE_ROW) {')
 		}
 		for i, field in node.fields {
diff --git a/vlib/v/parser/sql.v b/vlib/v/parser/sql.v
index 1db4d9e83b..48f70e6baf 100644
--- a/vlib/v/parser/sql.v
+++ b/vlib/v/parser/sql.v
@@ -38,13 +38,17 @@ fn (mut p Parser) sql_expr() ast.Expr {
 			}
 		}
 	}
+	mut has_limit := false
+	mut limit_expr := ast.Expr{}
 	if p.tok.kind == .name && p.tok.lit == 'limit' {
 		// `limit 1` means that a single object is returned
 		p.check_name() // `limit`
 		if p.tok.kind == .number && p.tok.lit == '1' {
 			query_one = true
+		} else {
+			has_limit = true
 		}
-		p.next()
+		limit_expr = p.expr(0)
 	}
 	if !query_one && !is_count {
 		// return an array
@@ -63,6 +67,8 @@ fn (mut p Parser) sql_expr() ast.Expr {
 		table_type: table_type
 		where_expr: where_expr
 		has_where: has_where
+		has_limit: has_limit
+		limit_expr: limit_expr
 		is_array: !query_one
 		pos: pos
 	}