Allow more variations of LIMIT/OFFSET

In addtion to already supported LIMIT/OFFSET variants allow more to be parsed

Legacy:
  - LIMIT int
  - LIMIT int OFFSET int

Enhancement:
  - OFFSET int             (no limit)
  - LIMIT ALL              (no limit)
  - LIMIT NULL             (no limit)
  - LIMIT ALL OFFSET int   (no limit, but offset)
  - LIMIT NULL OFFSET int  (no limit, but offset)

Also ensures negative limits / offsets are set to kNoLimit/kNoOffset

src/parser/bison_parser.y

@@ -711,6 +711,11 @@ opt_top:
 opt_limit:
 		LIMIT int_literal { $$ = new LimitDescription($2->ival, kNoOffset); delete $2; }
 	|	LIMIT int_literal OFFSET int_literal { $$ = new LimitDescription($2->ival, $4->ival); delete $2; delete $4; }
+	|	OFFSET int_literal { $$ = new LimitDescription(kNoLimit, $2->ival); delete $2; }
+	|	LIMIT ALL { $$ = nullptr; }
+	|	LIMIT NULL { $$ = nullptr;  }
+	|	LIMIT ALL OFFSET int_literal { $$ = new LimitDescription(kNoLimit, $4->ival); delete $4; }
+	|	LIMIT NULL OFFSET int_literal { $$ = new LimitDescription(kNoLimit, $4->ival);; delete $4; }
 	|	/* empty */ { $$ = nullptr; }
 	;
 

src/sql/statements.cpp

@@ -156,8 +156,8 @@ namespace hsql {
 
   // LimitDescription
   LimitDescription::LimitDescription(int64_t limit, int64_t offset) :
-    limit(limit),
+    limit(limit >= 0 ? limit : kNoLimit),
-    offset(offset) {}
+    offset(offset > 0 ? offset : kNoOffset) {}
 
   // GroypByDescription
   GroupByDescription::GroupByDescription() :

test/select_tests.cpp

@@ -439,3 +439,60 @@ TEST(JoinTypes) {
   stmt = (SelectStatement*) result.getStatement(11);
   ASSERT_NULL(stmt->fromTable->join);
 }
+
+TEST(SetLimitOffset) {
+  SelectStatement* stmt;
+
+  TEST_PARSE_SQL_QUERY("select a from t1 limit 1; \
+                    select a from t1 limit 1 offset 1; \
+                    select a from t1 limit 0; \
+                    select a from t1 limit 0 offset 1; \
+                    select a from t1 limit 1 offset 0; \
+                    select a from t1 limit ALL offset 1; \
+                    select a from t1 limit NULL offset 1; \
+                    select a from t1 offset 1; \
+                    select top 10 a from t1; \
+                    select top 20 a from t1 limit 10;",
+        result, 10);
+
+  stmt = (SelectStatement*) result.getStatement(0);
+  ASSERT_EQ(stmt->limit->limit, 1);
+  ASSERT_EQ(stmt->limit->offset, kNoOffset);
+
+  stmt = (SelectStatement*) result.getStatement(1);
+  ASSERT_EQ(stmt->limit->limit, 1);
+  ASSERT_EQ(stmt->limit->offset, 1);
+
+  stmt = (SelectStatement*) result.getStatement(2);
+  ASSERT_EQ(stmt->limit->limit, 0);
+  ASSERT_EQ(stmt->limit->offset, kNoOffset);
+
+  stmt = (SelectStatement*) result.getStatement(3);
+  ASSERT_EQ(stmt->limit->limit, 0);
+  ASSERT_EQ(stmt->limit->offset, 1);
+
+  stmt = (SelectStatement*) result.getStatement(4);
+  ASSERT_EQ(stmt->limit->limit, 1);
+  ASSERT_EQ(stmt->limit->offset, kNoOffset);
+
+  stmt = (SelectStatement*) result.getStatement(5);
+  ASSERT_EQ(stmt->limit->limit, kNoLimit);
+    ASSERT_EQ(stmt->limit->offset, 1);
+
+  stmt = (SelectStatement*) result.getStatement(6);
+  ASSERT_EQ(stmt->limit->limit, kNoLimit);
+  ASSERT_EQ(stmt->limit->offset, 1);
+
+  stmt = (SelectStatement*) result.getStatement(7);
+  ASSERT_EQ(stmt->limit->limit, kNoLimit);
+  ASSERT_EQ(stmt->limit->offset, 1);
+
+  stmt = (SelectStatement*) result.getStatement(8);
+  ASSERT_EQ(stmt->limit->limit, 10);
+  ASSERT_EQ(stmt->limit->offset, kNoOffset);
+
+  stmt = (SelectStatement*) result.getStatement(9);
+  ASSERT_EQ(stmt->limit->limit, 10);
+  ASSERT_EQ(stmt->limit->offset, kNoOffset);
+}
+