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2786055df4
- New parser written from scratch, allows easier and complete parsing of the full S3 Select SQL syntax. Parser definition is directly provided by the AST defined for the SQL grammar. - Bring support to parse and interpret SQL involving JSON path expressions; evaluation of JSON path expressions will be subsequently added. - Bring automatic type inference and conversion for untyped values (e.g. CSV data).
101 lines
2.5 KiB
Go
101 lines
2.5 KiB
Go
/*
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* Minio Cloud Storage, (C) 2019 Minio, Inc.
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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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*/
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package csv
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import (
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"bytes"
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"encoding/csv"
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"fmt"
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"github.com/minio/minio/pkg/s3select/sql"
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"github.com/tidwall/sjson"
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)
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// Record - is CSV record.
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type Record struct {
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columnNames []string
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csvRecord []string
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nameIndexMap map[string]int64
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}
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// Get - gets the value for a column name. CSV fields do not have any
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// defined type (other than the default string). So this function
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// always returns fields using sql.FromBytes so that the type
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// specified/implied by the query can be used, or can be automatically
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// converted based on the query.
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func (r *Record) Get(name string) (*sql.Value, error) {
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index, found := r.nameIndexMap[name]
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if !found {
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return nil, fmt.Errorf("column %v not found", name)
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}
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if index >= int64(len(r.csvRecord)) {
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// No value found for column 'name', hence return null
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// value
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return sql.FromNull(), nil
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}
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return sql.FromBytes([]byte(r.csvRecord[index])), nil
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}
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// Set - sets the value for a column name.
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func (r *Record) Set(name string, value *sql.Value) error {
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r.columnNames = append(r.columnNames, name)
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r.csvRecord = append(r.csvRecord, value.CSVString())
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return nil
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}
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// MarshalCSV - encodes to CSV data.
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func (r *Record) MarshalCSV(fieldDelimiter rune) ([]byte, error) {
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buf := new(bytes.Buffer)
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w := csv.NewWriter(buf)
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w.Comma = fieldDelimiter
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if err := w.Write(r.csvRecord); err != nil {
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return nil, err
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}
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w.Flush()
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if err := w.Error(); err != nil {
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return nil, err
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}
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data := buf.Bytes()
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return data[:len(data)-1], nil
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}
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// MarshalJSON - encodes to JSON data.
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func (r *Record) MarshalJSON() ([]byte, error) {
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data := "{}"
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var err error
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for i := len(r.columnNames) - 1; i >= 0; i-- {
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if i >= len(r.csvRecord) {
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continue
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}
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if data, err = sjson.Set(data, r.columnNames[i], r.csvRecord[i]); err != nil {
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return nil, err
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}
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}
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return []byte(data), nil
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}
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// NewRecord - creates new CSV record.
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func NewRecord() *Record {
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return &Record{}
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}
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