From f82504b3199686491c211c1960906e6ccf89f84c Mon Sep 17 00:00:00 2001
From: Pedro <pedroflemming@gmail.com>
Date: Tue, 7 Mar 2017 02:30:44 +0100
Subject: [PATCH] Allow order by to define a list of expressions to order by

---
 src/parser/bison_parser.y | 39 ++++++++++++++++++++++++++++-----------
 src/sql/SelectStatement.h |  2 +-
 src/sqlhelper.cpp         |  4 ++--
 test/select_tests.cpp     | 20 ++++++++++++++++++++
 test/valid_queries.sql    |  1 +
 5 files changed, 52 insertions(+), 14 deletions(-)

diff --git a/src/parser/bison_parser.y b/src/parser/bison_parser.y
index be3c72a..88d5e23 100644
--- a/src/parser/bison_parser.y
+++ b/src/parser/bison_parser.y
@@ -131,6 +131,7 @@ int yyerror(YYLTYPE* llocp, SQLParserResult** result, yyscan_t scanner, const ch
 	std::vector<hsql::ColumnDefinition*>* column_vec;
 	std::vector<hsql::UpdateClause*>* update_vec;
 	std::vector<hsql::Expr*>* expr_vec;
+	std::vector<hsql::OrderDescription*>* order_vec;
 }
 
 
@@ -146,7 +147,7 @@ int yyerror(YYLTYPE* llocp, SQLParserResult** result, yyscan_t scanner, const ch
 		}
 	}
 	delete ($$);
-} <str_vec> <table_vec> <column_vec> <update_vec> <expr_vec>
+} <str_vec> <table_vec> <column_vec> <update_vec> <expr_vec> <order_vec>
 %destructor { delete ($$); } <*>
 
 
@@ -197,8 +198,8 @@ int yyerror(YYLTYPE* llocp, SQLParserResult** result, yyscan_t scanner, const ch
 %type <expr> 		expr scalar_expr unary_expr binary_expr function_expr star_expr expr_alias placeholder_expr
 %type <expr> 		column_name literal int_literal num_literal string_literal
 %type <expr> 		comp_expr opt_where join_condition opt_having
-%type <order>		opt_order
-%type <limit>		opt_limit
+%type <limit>		opt_limit opt_top
+%type <order>		order_desc
 %type <order_type>	opt_order_type
 %type <column_t>	column_def
 %type <update_t>	update_clause
@@ -207,6 +208,7 @@ int yyerror(YYLTYPE* llocp, SQLParserResult** result, yyscan_t scanner, const ch
 %type <str_vec>		ident_commalist opt_column_list
 %type <expr_vec> 	expr_list select_list literal_list
 %type <table_vec> 	table_ref_commalist
+%type <order_vec>	opt_order order_list
 %type <update_vec>	update_clause_commalist
 %type <column_vec>	column_def_commalist
 
@@ -502,13 +504,14 @@ set_operator:
 	;
 
 select_clause:
-		SELECT opt_distinct select_list from_clause opt_where opt_group {
+		SELECT opt_top opt_distinct select_list from_clause opt_where opt_group {
 			$$ = new SelectStatement();
-			$$->selectDistinct = $2;
-			$$->selectList = $3;
-			$$->fromTable = $4;
-			$$->whereClause = $5;
-			$$->groupBy = $6;
+			$$->limit = $2;
+			$$->selectDistinct = $3;
+			$$->selectList = $4;
+			$$->fromTable = $5;
+			$$->whereClause = $6;
+			$$->groupBy = $7;
 		}
 	;
 
@@ -521,7 +524,6 @@ select_list:
 		expr_list
 	;
 
-
 from_clause:
 		FROM table_ref { $$ = $2; }
 	;
@@ -546,16 +548,31 @@ opt_having:
 	|	/* empty */ { $$ = NULL; }
 
 opt_order:
-		ORDER BY expr opt_order_type { $$ = new OrderDescription($4, $3); }
+		ORDER BY order_list { $$ = $3; }
 	|	/* empty */ { $$ = NULL; }
 	;
 
+order_list:
+		order_desc { $$ = new std::vector<OrderDescription*>(); $$->push_back($1); }
+	|	order_list ',' order_desc { $1->push_back($3); $$ = $1; }
+	;
+
+order_desc:
+		expr opt_order_type { $$ = new OrderDescription($2, $1); }
+	;
+
 opt_order_type:
 		ASC { $$ = kOrderAsc; }
 	|	DESC { $$ = kOrderDesc; }
 	|	/* empty */ { $$ = kOrderAsc; }
 	;
 
+// TODO: TOP and LIMIT can take more than just int literals.
+
+opt_top:
+		TOP int_literal { $$ = new LimitDescription($2->ival, kNoOffset); delete $2; }
+	|	/* empty */ { $$ = NULL; }
+	;
 
 opt_limit:
 		LIMIT int_literal { $$ = new LimitDescription($2->ival, kNoOffset); delete $2; }
diff --git a/src/sql/SelectStatement.h b/src/sql/SelectStatement.h
index a9d169d..bb60836 100644
--- a/src/sql/SelectStatement.h
+++ b/src/sql/SelectStatement.h
@@ -63,7 +63,7 @@ namespace hsql {
     GroupByDescription* groupBy;
 
     SelectStatement* unionSelect;
-    OrderDescription* order;
+    std::vector<OrderDescription*>* order;
     LimitDescription* limit;
   };
 
diff --git a/src/sqlhelper.cpp b/src/sqlhelper.cpp
index 5a47df8..529cead 100644
--- a/src/sqlhelper.cpp
+++ b/src/sqlhelper.cpp
@@ -139,8 +139,8 @@ namespace hsql {
 
     if (stmt->order != NULL) {
       inprint("OrderBy:", numIndent + 1);
-      printExpression(stmt->order->expr, numIndent + 2);
-      if (stmt->order->type == kOrderAsc) inprint("ascending", numIndent + 2);
+      printExpression(stmt->order->at(0)->expr, numIndent + 2);
+      if (stmt->order->at(0)->type == kOrderAsc) inprint("ascending", numIndent + 2);
       else inprint("descending", numIndent + 2);
     }
 
diff --git a/test/select_tests.cpp b/test/select_tests.cpp
index e302a84..dead654 100644
--- a/test/select_tests.cpp
+++ b/test/select_tests.cpp
@@ -73,3 +73,23 @@ TEST(SelectGroupDistinctTest) {
 }
 
 
+TEST(OrderByTest) {
+  TEST_PARSE_SINGLE_SQL(
+    "SELECT grade, city FROM students ORDER BY grade, city DESC;",
+    kStmtSelect,
+    SelectStatement,
+    result,
+    stmt);
+
+  ASSERT_NULL(stmt->whereClause);
+  ASSERT_NOTNULL(stmt->order);
+
+  ASSERT_EQ(stmt->order->size(), 2);
+  ASSERT_EQ(stmt->order->at(0)->type, kOrderAsc);
+  ASSERT_STREQ(stmt->order->at(0)->expr->name, "grade");
+
+  ASSERT_EQ(stmt->order->at(1)->type, kOrderDesc);
+  ASSERT_STREQ(stmt->order->at(1)->expr->name, "city");
+
+  delete result;
+}
diff --git a/test/valid_queries.sql b/test/valid_queries.sql
index b211cbf..dfece3d 100644
--- a/test/valid_queries.sql
+++ b/test/valid_queries.sql
@@ -8,6 +8,7 @@ SELECT * FROM "table" LIMIT 10 OFFSET 10; SELECT * FROM second;
 SELECT * FROM t1 UNION SELECT * FROM t2 ORDER BY col1;
 SELECT * FROM (SELECT * FROM t1);
 SELECT * FROM t1 UNION (SELECT * FROM t2 UNION SELECT * FROM t3) ORDER BY col1;
+SELECT TOP 10 * FROM t1 ORDER BY col1, col2;
 # JOIN
 SELECT t1.a, t1.b, t2.c FROM "table" AS t1 JOIN (SELECT * FROM foo JOIN bar ON foo.id = bar.id) t2 ON t1.a = t2.b WHERE (t1.b OR NOT t1.a) AND t2.c = 12.5
 SELECT * FROM t1 JOIN t2 ON c1 = c2;