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shape.go
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shape.go
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// Copyright 2017 The Cayley Authors. All rights reserved.
//
// 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
import (
"context"
"fmt"
"strconv"
"strings"
"github.com/aperturerobotics/cayley/graph"
"github.com/aperturerobotics/cayley/graph/iterator"
"github.com/aperturerobotics/cayley/quad"
"github.com/aperturerobotics/cayley/query/shape"
)
var DefaultDialect = QueryDialect{
FieldQuote: func(s string) string {
return strconv.Quote(s)
},
Placeholder: func(_ int) string {
return "?"
},
}
type QueryDialect struct {
RegexpOp CmpOp
FieldQuote func(string) string
Placeholder func(int) string
}
func NewBuilder(d QueryDialect) *Builder {
return &Builder{d: d}
}
type Builder struct {
d QueryDialect
pi int
}
func needQuotes(s string) bool {
for i, r := range s {
if (r < 'a' || r > 'z') && r != '_' && (i == 0 || r < '0' || r > '9') {
return true
}
}
return false
}
func (b *Builder) EscapeField(s string) string {
if !needQuotes(s) {
return s
}
return b.d.FieldQuote(s)
}
func (b *Builder) Placeholder() string {
b.pi++
return b.d.Placeholder(b.pi)
}
const (
tagPref = "__"
tagNode = tagPref + "node"
)
func dirField(d quad.Direction) string {
return d.String() + "_hash"
}
func dirTag(d quad.Direction) string {
return tagPref + d.String()
}
type Value interface {
SQLValue() interface{}
}
type Shape interface {
SQL(b *Builder) string
Args() []Value
Columns() []string
}
func AllNodes() Select {
return Nodes(nil, nil)
}
func Nodes(where []Where, params []Value) Select {
return Select{
Fields: []Field{
{Name: "hash", Alias: tagNode},
},
From: []Source{
Table{Name: "nodes"},
},
Where: where,
Params: params,
}
}
func AllQuads(alias string) Select {
sel := Select{
From: []Source{
Table{Name: "quads", Alias: alias},
},
}
for _, d := range quad.Directions {
sel.Fields = append(sel.Fields, Field{
Table: alias,
Name: dirField(d),
Alias: dirTag(d),
})
}
return sel
}
type FieldName struct {
Name string
Table string
}
func (FieldName) isExpr() {}
func (f FieldName) SQL(b *Builder) string {
name := b.EscapeField(f.Name)
if f.Table != "" {
name = f.Table + "." + name
}
return name
}
type Field struct {
Name string
Raw bool // do not quote Name
Alias string
Table string
}
func (f Field) SQL(b *Builder) string {
name := f.Name
if !f.Raw {
name = b.EscapeField(name)
}
if f.Table != "" {
name = f.Table + "." + name
}
if f.Alias == "" {
return name
}
return name + " AS " + b.EscapeField(f.Alias)
}
func (f Field) NameOrAlias() string {
if f.Alias != "" {
return f.Alias
}
return f.Name
}
type Source interface {
SQL(b *Builder) string
Args() []Value
isSource()
}
type Table struct {
Name string
Alias string
}
func (Table) isSource() {}
type Subquery struct {
Query Select
Alias string
}
func (Subquery) isSource() {}
func (s Subquery) SQL(b *Builder) string {
q := "(" + s.Query.SQL(b) + ")"
if s.Alias != "" {
q += " AS " + b.EscapeField(s.Alias)
}
return q
}
func (s Subquery) Args() []Value {
return s.Query.Args()
}
func (f Table) SQL(b *Builder) string {
if f.Alias == "" {
return f.Name
}
return f.Name + " AS " + b.EscapeField(f.Alias)
}
func (f Table) Args() []Value {
return nil
}
func (f Table) NameSQL() string {
if f.Alias != "" {
return f.Alias
}
return f.Name
}
type CmpOp string
const (
OpEqual = CmpOp("=")
OpGT = CmpOp(">")
OpGTE = CmpOp(">=")
OpLT = CmpOp("<")
OpLTE = CmpOp("<=")
OpIsNull = CmpOp("IS NULL")
OpIsTrue = CmpOp("IS true")
)
type Expr interface {
isExpr()
SQL(b *Builder) string
}
type Placeholder struct{}
func (Placeholder) isExpr() {}
func (Placeholder) SQL(b *Builder) string {
return b.Placeholder()
}
type Where struct {
Field string
Table string
Op CmpOp
Value Expr
}
func (w Where) SQL(b *Builder) string {
name := w.Field
if w.Table != "" {
name = w.Table + "." + b.EscapeField(name)
}
parts := []string{name, string(w.Op)}
if w.Value != nil {
parts = append(parts, w.Value.SQL(b))
}
return strings.Join(parts, " ")
}
var _ Shape = Select{}
// Select is a simplified representation of SQL SELECT query.
type Select struct {
Fields []Field
From []Source
Where []Where
Params []Value
Limit int64
Offset int64
// TODO(dennwc): this field in unexported because we don't want it to a be a part of the API
// however, it's necessary to make NodesFrom optimizations to work with SQL
nextPath bool
}
func (s Select) Clone() Select {
s.Fields = append([]Field{}, s.Fields...)
s.From = append([]Source{}, s.From...)
s.Where = append([]Where{}, s.Where...)
s.Params = append([]Value{}, s.Params...)
return s
}
func (s Select) isAll() bool {
return len(s.From) == 1 && len(s.Where) == 0 && len(s.Params) == 0 && !s.onlyAsSubquery()
}
// onlyAsSubquery indicates that query cannot be merged into existing SELECT because of some specific properties of query.
// An example of such properties might be LIMIT, DISTINCT, etc.
func (s Select) onlyAsSubquery() bool {
return s.Limit > 0 || s.Offset > 0
}
func (s Select) Columns() []string {
names := make([]string, 0, len(s.Fields))
for _, f := range s.Fields {
name := f.Alias
if name == "" {
name = f.Name
}
names = append(names, name)
}
return names
}
func (s Select) BuildIterator(ctx context.Context, qs graph.QuadStore) iterator.Shape {
sq, ok := qs.(*QuadStore)
if !ok {
return iterator.NewError(fmt.Errorf("not a SQL quadstore: %T", qs))
}
return sq.newIterator(s)
}
func (s Select) Optimize(ctx context.Context, r shape.Optimizer) (shape.Shape, bool, error) {
// TODO: call optimize on sub-tables? but what if it decides to de-optimize our SQL shape?
return s, false, nil
}
func (s *Select) AppendParam(o Value) Expr {
s.Params = append(s.Params, o)
return Placeholder{}
}
func (s *Select) WhereEq(tbl, field string, v Value) {
s.Where = append(s.Where, Where{
Table: tbl,
Field: field,
Op: OpEqual,
Value: s.AppendParam(v),
})
}
func (s Select) SQL(b *Builder) string {
var parts []string
var fields []string
for _, f := range s.Fields {
fields = append(fields, f.SQL(b))
}
parts = append(parts, "SELECT "+strings.Join(fields, ", "))
var tables []string
for _, t := range s.From {
tables = append(tables, t.SQL(b))
}
parts = append(parts, "FROM "+strings.Join(tables, ", "))
if len(s.Where) != 0 {
var wheres []string
for _, w := range s.Where {
wheres = append(wheres, w.SQL(b))
}
parts = append(parts, "WHERE "+strings.Join(wheres, " AND "))
}
if s.Limit > 0 {
parts = append(parts, "LIMIT "+strconv.FormatInt(s.Limit, 10))
}
if s.Offset > 0 {
parts = append(parts, "OFFSET "+strconv.FormatInt(s.Offset, 10))
}
sep := " "
if len(fields) > 1 {
sep = "\n\t"
}
return strings.Join(parts, sep)
}
func (s Select) Args() []Value {
var args []Value
// first add args for FROM subqueries
for _, q := range s.From {
args = append(args, q.Args()...)
}
// and add params for WHERE
args = append(args, s.Params...)
return args
}