155 lines
3.5 KiB
Go
155 lines
3.5 KiB
Go
package sqlbuilder
|
|
|
|
import (
|
|
"github.com/dropbox/godropbox/errors"
|
|
)
|
|
|
|
// An expression
|
|
type expression interface {
|
|
clause
|
|
projection
|
|
groupByClause
|
|
orderByClause
|
|
|
|
IN(subQuery selectStatement) boolExpression
|
|
NOT_IN(subQuery selectStatement) boolExpression
|
|
|
|
AS(alias string) projection
|
|
IS_DISTINCT_FROM(expression expression) boolExpression
|
|
IS_NULL() boolExpression
|
|
ASC() orderByClause
|
|
DESC() orderByClause
|
|
}
|
|
|
|
type expressionInterfaceImpl struct {
|
|
parent expression
|
|
}
|
|
|
|
func (e *expressionInterfaceImpl) IN(subQuery selectStatement) boolExpression {
|
|
return newBinaryBoolExpression(e.parent, subQuery, "IN")
|
|
}
|
|
|
|
func (e *expressionInterfaceImpl) NOT_IN(subQuery selectStatement) boolExpression {
|
|
return newBinaryBoolExpression(e.parent, subQuery, "NOT_IN")
|
|
}
|
|
|
|
func (e *expressionInterfaceImpl) AS(alias string) projection {
|
|
return NewAlias(e.parent, alias)
|
|
}
|
|
|
|
func (e *expressionInterfaceImpl) IS_DISTINCT_FROM(expression expression) boolExpression {
|
|
return newBinaryBoolExpression(e.parent, expression, "IS DISTINCT FROM")
|
|
}
|
|
|
|
func (e *expressionInterfaceImpl) IS_NULL() boolExpression {
|
|
return nil
|
|
}
|
|
|
|
func (e *expressionInterfaceImpl) ASC() orderByClause {
|
|
return &orderByClauseImpl{expression: e.parent, ascent: true}
|
|
}
|
|
|
|
func (e *expressionInterfaceImpl) DESC() orderByClause {
|
|
return &orderByClauseImpl{expression: e.parent, ascent: false}
|
|
}
|
|
|
|
func (e *expressionInterfaceImpl) serializeForGroupBy(statement statementType, out *queryData) error {
|
|
return e.parent.serialize(statement, out)
|
|
}
|
|
|
|
func (e *expressionInterfaceImpl) serializeForProjection(statement statementType, out *queryData) error {
|
|
return e.parent.serialize(statement, out)
|
|
}
|
|
|
|
func (e *expressionInterfaceImpl) serializeAsOrderBy(statement statementType, out *queryData) error {
|
|
return e.parent.serialize(statement, out)
|
|
}
|
|
|
|
// Representation of binary operations (e.g. comparisons, arithmetic)
|
|
type binaryExpression struct {
|
|
lhs, rhs expression
|
|
operator string
|
|
}
|
|
|
|
func newBinaryExpression(lhs, rhs expression, operator string, parent ...expression) binaryExpression {
|
|
binaryExpression := binaryExpression{
|
|
lhs: lhs,
|
|
rhs: rhs,
|
|
operator: operator,
|
|
}
|
|
|
|
return binaryExpression
|
|
}
|
|
|
|
func isSimpleOperand(expression expression) bool {
|
|
if _, ok := expression.(*literalExpression); ok {
|
|
return true
|
|
}
|
|
if _, ok := expression.(column); ok {
|
|
return true
|
|
}
|
|
if _, ok := expression.(*numericFunc); ok {
|
|
return true
|
|
}
|
|
|
|
return false
|
|
}
|
|
|
|
func (c *binaryExpression) serialize(statement statementType, out *queryData) error {
|
|
if c.lhs == nil {
|
|
return errors.Newf("nil lhs.")
|
|
}
|
|
if c.rhs == nil {
|
|
return errors.Newf("nil rhs.")
|
|
}
|
|
|
|
wrap := !isSimpleOperand(c.lhs) && !isSimpleOperand(c.rhs)
|
|
|
|
if wrap {
|
|
out.writeString("(")
|
|
}
|
|
|
|
if err := c.lhs.serialize(statement, out); err != nil {
|
|
return err
|
|
}
|
|
|
|
out.writeString(" " + c.operator + " ")
|
|
|
|
if err := c.rhs.serialize(statement, out); err != nil {
|
|
return err
|
|
}
|
|
|
|
if wrap {
|
|
out.writeString(")")
|
|
}
|
|
|
|
return nil
|
|
}
|
|
|
|
// A not expression which negates a expression value
|
|
type prefixExpression struct {
|
|
expression expression
|
|
operator string
|
|
}
|
|
|
|
func newPrefixExpression(expression expression, operator string) prefixExpression {
|
|
prefixExpression := prefixExpression{
|
|
expression: expression,
|
|
operator: operator,
|
|
}
|
|
|
|
return prefixExpression
|
|
}
|
|
|
|
func (p *prefixExpression) serialize(statement statementType, out *queryData) error {
|
|
out.writeString(p.operator + " ")
|
|
|
|
if p.expression == nil {
|
|
return errors.Newf("nil prefix expression.")
|
|
}
|
|
if err := p.expression.serialize(statement, out); err != nil {
|
|
return err
|
|
}
|
|
|
|
return nil
|
|
}
|