surrealpatch/sql/select.go
2017-02-20 01:44:13 +00:00

308 lines
6.1 KiB
Go

// Copyright © 2016 Abcum Ltd
//
// 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
func (p *parser) parseSelectStatement() (stmt *SelectStatement, err error) {
stmt = &SelectStatement{}
if stmt.KV, stmt.NS, stmt.DB, err = p.o.get(AuthSC); err != nil {
return nil, err
}
if stmt.Expr, err = p.parseField(); err != nil {
return nil, err
}
_, _, err = p.shouldBe(FROM)
if err != nil {
return nil, err
}
if stmt.What, err = p.parseWhat(); err != nil {
return nil, err
}
if stmt.Cond, err = p.parseCond(); err != nil {
return nil, err
}
if stmt.Group, err = p.parseGroup(); err != nil {
return nil, err
}
if stmt.Order, err = p.parseOrder(); err != nil {
return nil, err
}
if stmt.Limit, err = p.parseLimit(); err != nil {
return nil, err
}
if stmt.Start, err = p.parseStart(); err != nil {
return nil, err
}
if stmt.Version, err = p.parseVersion(); err != nil {
return nil, err
}
if _, _, err = p.shouldBe(EOF, RPAREN, SEMICOLON); err != nil {
return nil, err
}
return stmt, nil
}
func (p *parser) parseField() (mul []*Field, err error) {
var lit string
var exi bool
for {
one := &Field{}
one.Expr, err = p.parseExpr()
if err != nil {
return
}
one.Alias = "*" // TODO need to implement default field name
// Chec to see if the next token is an AS
// clause, and if it is read the defined
// field alias name from the scanner.
if _, _, exi = p.mightBe(AS); exi {
if _, one.Alias, err = p.shouldBe(IDENT); err != nil {
return nil, &ParseError{Found: lit, Expected: []string{"field alias"}}
}
}
// Append the single expression to the array
// of return statement expressions.
mul = append(mul, one)
// Check to see if the next token is a comma
// and if not, then break out of the loop,
// otherwise repeat until we find no comma.
if _, _, exi = p.mightBe(COMMA); !exi {
break
}
}
return
}
func (p *parser) parseWhere() (exp Expr, err error) {
// The next token that we expect to see is a
// WHERE token, and if we don't find one then
// return nil, with no error.
if _, _, exi := p.mightBe(WHERE); !exi {
return nil, nil
}
return p.parseExpr()
}
func (p *parser) parseGroup() (mul []*Group, err error) {
// The next token that we expect to see is a
// GROUP token, and if we don't find one then
// return nil, with no error.
if _, _, exi := p.mightBe(GROUP); !exi {
return nil, nil
}
// We don't need to have a BY token, but we
// allow it so that the SQL query would read
// better when compared to english.
_, _, _ = p.mightBe(BY)
for {
var tok Token
var lit string
one := &Group{}
tok, lit, err = p.shouldBe(IDENT, ID)
if err != nil {
return nil, &ParseError{Found: lit, Expected: []string{"field name"}}
}
one.Expr, err = p.declare(tok, lit)
if err != nil {
return nil, err
}
// Append the single expression to the array
// of return statement expressions.
mul = append(mul, one)
// Check to see if the next token is a comma
// and if not, then break out of the loop,
// otherwise repeat until we find no comma.
if _, _, exi := p.mightBe(COMMA); !exi {
break
}
}
return
}
func (p *parser) parseOrder() (mul []*Order, err error) {
// The next token that we expect to see is a
// ORDER token, and if we don't find one then
// return nil, with no error.
if _, _, exi := p.mightBe(ORDER); !exi {
return nil, nil
}
// We don't need to have a BY token, but we
// allow it so that the SQL query would read
// better when compared to english.
_, _, _ = p.mightBe(BY)
for {
var exi bool
var tok Token
var lit string
one := &Order{}
tok, lit, err = p.shouldBe(IDENT, ID)
if err != nil {
return nil, &ParseError{Found: lit, Expected: []string{"field name"}}
}
one.Expr, err = p.declare(tok, lit)
if err != nil {
return nil, err
}
if tok, lit, exi = p.mightBe(ASC, DESC); !exi {
tok = ASC
}
one.Dir, err = p.declare(tok, lit)
if err != nil {
return nil, err
}
// Append the single expression to the array
// of return statement expressions.
mul = append(mul, one)
// Check to see if the next token is a comma
// and if not, then break out of the loop,
// otherwise repeat until we find no comma.
if _, _, exi := p.mightBe(COMMA); !exi {
break
}
}
return
}
func (p *parser) parseLimit() (Expr, error) {
// The next token that we expect to see is a
// LIMIT token, and if we don't find one then
// return nil, with no error.
if _, _, exi := p.mightBe(LIMIT); !exi {
return nil, nil
}
// We don't need to have a BY token, but we
// allow it so that the SQL query would read
// better when compared to english.
_, _, _ = p.mightBe(BY)
tok, lit, err := p.shouldBe(NUMBER, PARAM)
if err != nil {
return nil, &ParseError{Found: lit, Expected: []string{"limit number"}}
}
return p.declare(tok, lit)
}
func (p *parser) parseStart() (Expr, error) {
// The next token that we expect to see is a
// START token, and if we don't find one then
// return nil, with no error.
if _, _, exi := p.mightBe(START); !exi {
return nil, nil
}
// We don't need to have a AT token, but we
// allow it so that the SQL query would read
// better when compared to english.
_, _, _ = p.mightBe(AT)
tok, lit, err := p.shouldBe(NUMBER, PARAM)
if err != nil {
return nil, &ParseError{Found: lit, Expected: []string{"start number"}}
}
return p.declare(tok, lit)
}
func (p *parser) parseVersion() (Expr, error) {
if _, _, exi := p.mightBe(VERSION, ON); !exi {
return nil, nil
}
tok, lit, err := p.shouldBe(DATE, TIME, PARAM)
if err != nil {
return nil, &ParseError{Found: lit, Expected: []string{"timestamp"}}
}
return p.declare(tok, lit)
}