Simplify API.

src/query/parser.go

@@ -53,6 +53,12 @@ type Query struct {
 	groupByClause GroupByClause
 	Limit         int
 }
+func (self *WhereCondition) GetBoolExpression() (*BoolExpression, bool) {
+	if self.isBooleanExpression {
+		return self.Left.(*BoolExpression), true
+	}
+	return nil, false
+}
 
 func (self *Query) GetColumnNames() []*Value {
 	if self.ColumnNames != nil {
@@ -67,6 +73,13 @@ func (self *Query) GetFromClause() *Value {
 	return GetValue(self.q.f)
 }
 
+func (self *Expression) GetSimpleValue() (*Value, bool) {
+	if self.Operation == '\000' {
+		return self.Left, true
+	}
+	return nil, false
+}
+
 func GetValueArray(array *C.value_array) []*Value {
 	if array == nil {
 		return nil

src/query/parser_test.go

@@ -32,15 +32,18 @@ func (self *QueryParserSuite) TestParseBasicSelectQuery(c *C) {
 	w := q.GetWhereCondition()
 	c.Assert(q.GetFromClause().Name, Equals, "t")
 
-	boolExpression := w.Left.(*BoolExpression)
+	boolExpression, ok := w.GetBoolExpression()
+	c.Assert(ok, Equals, true)
+
 	leftExpression := boolExpression.Left
 	rightExpression := boolExpression.Right
-	leftValue := leftExpression.Left.Name
-	rightValue := rightExpression.Left.Name
 
-	c.Assert(leftValue, Equals, "c")
+	leftValue, ok := leftExpression.GetSimpleValue() // simple value is an expression with one value, e.g. it doesn't combine value using arithmetic operations
+	rightValue, ok := rightExpression.GetSimpleValue()
+
+	c.Assert(leftValue.Name, Equals, "c")
 	c.Assert(boolExpression.Operation, Equals, "==")
-	c.Assert(rightValue, Equals, "5")
+	c.Assert(rightValue.Name, Equals, "5")
 }
 
 func (self *QueryParserSuite) TestParseSelectWithoutWhereClause(c *C) {