412 lines
8.1 KiB
Go
412 lines
8.1 KiB
Go
// Copyright © 2016 Abcum Ltd
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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package sql
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func (p *parser) parseSelectStatement() (stmt *SelectStatement, err error) {
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stmt = &SelectStatement{}
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if stmt.Expr, err = p.parseFields(); err != nil {
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return nil, err
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}
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_, _, err = p.shouldBe(FROM)
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if err != nil {
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return nil, err
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}
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if stmt.What, err = p.parseWhat(); err != nil {
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return nil, err
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}
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if stmt.Cond, err = p.parseCond(); err != nil {
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return nil, err
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}
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if stmt.Split, err = p.parseSplit(); err != nil {
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return nil, err
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}
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if stmt.Group, err = p.parseGroup(); err != nil {
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return nil, err
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}
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if stmt.Order, err = p.parseOrder(); err != nil {
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return nil, err
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}
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if stmt.Limit, err = p.parseLimit(); err != nil {
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return nil, err
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}
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if stmt.Start, err = p.parseStart(); err != nil {
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return nil, err
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}
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if stmt.Fetch, err = p.parseFetch(); err != nil {
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return nil, err
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}
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if stmt.Version, err = p.parseVersion(); err != nil {
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return nil, err
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}
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if stmt.Timeout, err = p.parseTimeout(); err != nil {
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return nil, err
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}
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if err = checkExpression(aggrs, stmt.Expr, stmt.Group); err != nil {
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return nil, err
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}
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// If this query has any subqueries which
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// need to alter the database then mark
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// this query as a writeable statement.
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stmt.RW = p.buf.rw
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return
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}
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func (p *parser) parseFields() (mul Fields, err error) {
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for {
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one := &Field{}
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one.Expr, err = p.parseExpr()
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if err != nil {
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return
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}
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// Chec to see if the next token is an AS
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// clause, and if it is read the defined
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// field alias name from the scanner.
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if _, _, exi := p.mightBe(AS); exi {
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if _, one.Alias, err = p.shouldBe(IDENT, EXPR); err != nil {
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return nil, &ParseError{Found: one.Alias, Expected: []string{"alias name"}}
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}
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one.Field = one.Alias
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} else {
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switch v := one.Expr.(type) {
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case *Param:
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one.Field = v.VA
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case *Ident:
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one.Field = v.VA
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case *Value:
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one.Field = v.VA
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default:
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one.Field = one.String()
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}
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}
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// Append the single expression to the array
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// of return statement expressions.
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mul = append(mul, one)
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// Check to see if the next token is a comma
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// and if not, then break out of the loop,
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// otherwise repeat until we find no comma.
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if _, _, exi := p.mightBe(COMMA); !exi {
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break
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}
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}
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return
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}
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func (p *parser) parseSplit() (Idents, error) {
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// The next token that we expect to see is a
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// SPLIT token, and if we don't find one then
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// return nil, with no error.
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if _, _, exi := p.mightBe(SPLIT); !exi {
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return nil, nil
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}
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// We don't need to have a ON token, but we
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// allow it so that the SQL query would read
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// better when compared to english.
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_, _, _ = p.mightBe(ON)
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return p.parseIdioms()
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}
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func (p *parser) parseGroup() (mul Groups, err error) {
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// The next token that we expect to see is a
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// GROUP token, and if we don't find one then
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// return nil, with no error.
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if _, _, exi := p.mightBe(GROUP); !exi {
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return nil, nil
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}
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// We don't need to have a BY token, but we
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// allow it so that the SQL query would read
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// better when compared to english.
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_, _, _ = p.mightBe(BY)
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// If the next token is the ALL keyword then
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// we will group all records together, which
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// will prevent grouping by other fields.
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if _, _, exi := p.mightBe(ALL); exi {
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mul = append(mul, &Group{
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Expr: new(All),
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})
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return
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}
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// Otherwise let's parse the fields with which
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// we will group the selected data, with
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// multiple fields grouped by commas.
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for {
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var tok Token
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var lit string
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one := &Group{}
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tok, lit, err = p.shouldBe(IDENT, EXPR)
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if err != nil {
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return nil, &ParseError{Found: lit, Expected: []string{"field name"}}
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}
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one.Expr, err = p.declare(tok, lit)
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if err != nil {
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return nil, err
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}
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// Append the single expression to the array
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// of return statement expressions.
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mul = append(mul, one)
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// Check to see if the next token is a comma
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// and if not, then break out of the loop,
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// otherwise repeat until we find no comma.
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if _, _, exi := p.mightBe(COMMA); !exi {
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break
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}
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}
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return
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}
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func (p *parser) parseOrder() (mul Orders, err error) {
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// The next token that we expect to see is a
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// ORDER token, and if we don't find one then
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// return nil, with no error.
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if _, _, exi := p.mightBe(ORDER); !exi {
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return nil, nil
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}
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// We don't need to have a BY token, but we
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// allow it so that the SQL query would read
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// better when compared to english.
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_, _, _ = p.mightBe(BY)
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for {
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var exi bool
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var tok Token
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var lit string
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one := &Order{}
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tok, lit, err = p.shouldBe(IDENT, EXPR, RAND)
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if err != nil {
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return nil, &ParseError{Found: lit, Expected: []string{"field name"}}
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}
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switch tok {
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default:
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one.Expr, err = p.declare(tok, lit)
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if err != nil {
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return nil, err
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}
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case RAND:
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one.Expr = &FuncExpression{Name: "rand"}
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if _, _, exi = p.mightBe(LPAREN); exi {
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_, _, err = p.shouldBe(RPAREN)
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if err != nil {
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return nil, err
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}
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}
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}
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if _, _, exi = p.mightBe(COLLATE); exi {
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one.Tag, err = p.parseLanguage()
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if err != nil {
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return nil, err
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}
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}
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if tok, _, exi = p.mightBe(ASC, DESC); exi {
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one.Dir = (tok == ASC)
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} else {
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one.Dir = true
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}
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// Append the single expression to the array
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// of return statement expressions.
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mul = append(mul, one)
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// Check to see if the next token is a comma
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// and if not, then break out of the loop,
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// otherwise repeat until we find no comma.
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if _, _, exi := p.mightBe(COMMA); !exi {
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break
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}
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}
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return
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}
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func (p *parser) parseLimit() (Expr, error) {
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// The next token that we expect to see is a
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// LIMIT token, and if we don't find one then
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// return nil, with no error.
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if _, _, exi := p.mightBe(LIMIT); !exi {
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return nil, nil
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}
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// We don't need to have a BY token, but we
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// allow it so that the SQL query would read
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// better when compared to english.
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_, _, _ = p.mightBe(BY)
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tok, lit, err := p.shouldBe(NUMBER, PARAM)
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if err != nil {
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return nil, &ParseError{Found: lit, Expected: []string{"limit number"}}
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}
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return p.declare(tok, lit)
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}
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func (p *parser) parseStart() (Expr, error) {
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// The next token that we expect to see is a
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// START token, and if we don't find one then
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// return nil, with no error.
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if _, _, exi := p.mightBe(START); !exi {
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return nil, nil
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}
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// We don't need to have a AT token, but we
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// allow it so that the SQL query would read
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// better when compared to english.
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_, _, _ = p.mightBe(AT)
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tok, lit, err := p.shouldBe(NUMBER, PARAM)
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if err != nil {
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return nil, &ParseError{Found: lit, Expected: []string{"start number"}}
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}
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return p.declare(tok, lit)
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}
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func (p *parser) parseFetch() (mul Fetchs, err error) {
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// The next token that we expect to see is a
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// GROUP token, and if we don't find one then
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// return nil, with no error.
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if _, _, exi := p.mightBe(FETCH); !exi {
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return nil, nil
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}
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for {
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var tok Token
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var lit string
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one := &Fetch{}
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tok, lit, err = p.shouldBe(IDENT, EXPR)
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if err != nil {
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return nil, &ParseError{Found: lit, Expected: []string{"field name"}}
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}
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one.Expr, err = p.declare(tok, lit)
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if err != nil {
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return nil, err
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}
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// Append the single expression to the array
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// of return statement expressions.
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mul = append(mul, one)
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// Check to see if the next token is a comma
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// and if not, then break out of the loop,
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// otherwise repeat until we find no comma.
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if _, _, exi := p.mightBe(COMMA); !exi {
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break
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}
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}
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return
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}
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func (p *parser) parseVersion() (Expr, error) {
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if _, _, exi := p.mightBe(VERSION, ON); !exi {
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return nil, nil
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}
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return p.parseExpr()
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}
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