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router.go
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router.go
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// Copyright 2020 Pilosa Corp.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
package sql
type router struct {
direct map[QueryMask]handler
filters []maskFilter
}
type maskFilter struct {
optional QueryMask
required []QueryMask
handler handler
}
func newRouter() *router {
selectRouter := &router{
direct: make(map[QueryMask]handler),
}
selectRouter.addFilter(
NewQueryMask(
SelectPartID|SelectPartStar|SelectPartField|SelectPartFields,
FromPartTable,
WherePartFieldCondition|WherePartMultiFieldCondition|WherePartIDCondition,
0,
0,
),
[]QueryMask{},
handlerSelectFieldsFromTableWhere{},
)
////
selectRouter.addRoute("select distinct fld from tbl", handlerSelectDistinctFromTable{})
////
selectRouter.addFilter(
NewQueryMask(
SelectPartCountStar|SelectPartCountField|SelectPartCountDistinctField,
FromPartTable,
WherePartFieldCondition|WherePartMultiFieldCondition|WherePartIDCondition,
0,
0,
),
[]QueryMask{},
handlerSelectCountFromTableWhere{},
)
////
selectRouter.addFilter(
NewQueryMask(
SelectPartMinField|SelectPartMaxField|SelectPartSumField|SelectPartAvgField,
FromPartTable,
WherePartFieldCondition|WherePartMultiFieldCondition|WherePartIDCondition,
0,
0,
),
[]QueryMask{},
handlerSelectFuncFromTableWhere{},
)
////
groupByOptional := NewQueryMask(
SelectPartField|SelectPartFields|SelectPartCountStar|SelectPartSumField,
FromPartTable,
WherePartFieldCondition, // TODO: this can probably handle fields as well
GroupByPartField|GroupByPartFields,
HavingPartCondition,
)
selectRouter.addFilter(
groupByOptional,
[]QueryMask{NewQueryMask(0, 0, 0, GroupByPartField, 0)},
handlerSelectGroupBy{},
)
selectRouter.addFilter(
groupByOptional,
[]QueryMask{NewQueryMask(0, 0, 0, GroupByPartFields, 0)},
handlerSelectGroupBy{},
)
selectRouter.addRoute("select fld, count(fld) from tbl group by fld", handlerSelectGroupBy{})
selectRouter.addRoute("select fld1, count(fld1) from tbl where fld2=1 group by fld1", handlerSelectGroupBy{})
selectRouter.addRoute("select count(*) from tbl1 INNER JOIN tbl2 ON tbl1._id = tbl2.bsi", handlerSelectJoin{})
selectRouter.addRoute("select count(*) from tbl1 INNER JOIN tbl2 ON tbl1._id = tbl2.bsi where fld1=1", handlerSelectJoin{})
selectRouter.addRoute("select count(*) from tbl1 INNER JOIN tbl2 ON tbl1._id = tbl2.bsi where fld1=1 and fld2=2", handlerSelectJoin{})
selectRouter.addRoute("select _id from tbl1 INNER JOIN tbl2 ON tbl1._id = tbl2.bsi", handlerSelectJoin{})
selectRouter.addRoute("select _id from tbl1 INNER JOIN tbl2 ON tbl1._id = tbl2.bsi where fld1=1", handlerSelectJoin{})
selectRouter.addRoute("select _id from tbl1 INNER JOIN tbl2 ON tbl1._id = tbl2.bsi where fld1=1 and fld2=2", handlerSelectJoin{})
return selectRouter
}
func (r *router) addRoute(sql string, handler handler) {
r.direct[MustGenerateMask(sql)] = handler
}
func (r *router) addFilter(opt QueryMask, req []QueryMask, handler handler) {
mf := maskFilter{
optional: opt,
required: req,
handler: handler,
}
r.filters = append(r.filters, mf)
}
func (r *router) handler(qm QueryMask) handler {
// First, check for a direct mapping.
// Zero out the orderBy and limit mask, because
// those are not specific to the query processing.
zm := QueryMask{
SelectMask: qm.SelectMask,
FromMask: qm.FromMask,
WhereMask: qm.WhereMask,
GroupByMask: qm.GroupByMask,
HavingMask: qm.HavingMask,
}
if h, ok := r.direct[zm]; ok {
return h
}
for _, mf := range r.filters {
if applyMaskFilter(&qm, mf) {
return mf.handler
}
}
return nil
}
// applyMaskFilter returns true if m passes the filter mf.
// Note: only certain query parts are included; namely,
// the orderBy and limit masks are not applied to the
// filter. A mask can satisfy any part of the optional
// filter to pass through, but it MUST satisfy all parts
// of the required filter.
func applyMaskFilter(m *QueryMask, mf maskFilter) bool {
if !m.ApplyFilter(mf.optional) {
return false
}
for _, req := range mf.required {
if m.SelectMask&req.SelectMask != req.SelectMask {
return false
}
if m.FromMask&req.FromMask != req.FromMask {
return false
}
if m.WhereMask&req.WhereMask != req.WhereMask {
return false
}
if m.GroupByMask&req.GroupByMask != req.GroupByMask {
return false
}
if m.HavingMask&req.HavingMask != req.HavingMask {
return false
}
}
return true
}