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DataTable.go
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DataTable.go
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//******************************************************************************************************
// DataTable.go - Gbtc
//
// Copyright © 2021, Grid Protection Alliance. All Rights Reserved.
//
// Licensed to the Grid Protection Alliance (GPA) under one or more contributor license agreements. See
// the NOTICE file distributed with this work for additional information regarding copyright ownership.
// The GPA licenses this file to you under the MIT License (MIT), the "License"; you may not use this
// file except in compliance with the License. You may obtain a copy of the License at:
//
// http://opensource.org/licenses/MIT
//
// Unless agreed to in writing, the subject software distributed under the License is distributed on an
// "AS-IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. Refer to the
// License for the specific language governing permissions and limitations.
//
// Code Modification History:
// ----------------------------------------------------------------------------------------------------
// 09/23/2021 - J. Ritchie Carroll
// Generated original version of source code.
//
//******************************************************************************************************
package data
import (
"errors"
"fmt"
"strings"
"github.com/sttp/goapi/sttp/format"
)
// DataTable represents a collection of DataColumn objects where each data column defines a name and
// a data type. Data columns can also be computed where its value would be derived from other columns
// and functions (https://sttp.github.io/documentation/filter-expressions/) defined in an expression.
// Note that this implementation uses a case-insensitive map for DataColumn name lookups. Internally,
// case-insensitive lookups are accomplished using `strings.ToUpper`.
type DataTable struct {
parent *DataSet
name string
columnIndexes map[string]int
columns []*DataColumn
rows []*DataRow
}
func newDataTable(parent *DataSet, name string) *DataTable {
return &DataTable{
parent: parent,
name: name,
columnIndexes: make(map[string]int),
}
}
// Parent gets the parent DataSet of the DataTable.
func (dt *DataTable) Parent() *DataSet {
return dt.parent
}
// Name gets the name of the DataTable.
func (dt *DataTable) Name() string {
return dt.name
}
// InitColumns initializes the internal column collection to the specified length.
// Any existing columns will be deleted.
func (dt *DataTable) InitColumns(length int) {
dt.columns = make([]*DataColumn, 0, length)
dt.columnIndexes = make(map[string]int, length)
}
// AddColumn adds the specified column to the DataTable.
func (dt *DataTable) AddColumn(column *DataColumn) {
column.index = len(dt.columns)
dt.columnIndexes[strings.ToUpper(column.Name())] = column.index
dt.columns = append(dt.columns, column)
}
// Column gets the DataColumn at the specified columnIndex if the index is in range;
// otherwise, nil is returned.
func (dt *DataTable) Column(columnIndex int) *DataColumn {
if columnIndex < 0 || columnIndex >= len(dt.columns) {
return nil
}
return dt.columns[columnIndex]
}
// ColumnByName gets the DataColumn for the specified columnName if the name exists;
// otherwise, nil is returned. Lookup is case-insensitive.
func (dt *DataTable) ColumnByName(columnName string) *DataColumn {
if columnIndex, ok := dt.columnIndexes[strings.ToUpper(columnName)]; ok {
return dt.Column(columnIndex)
}
return nil
}
// ColumnIndex gets the index for the specified columnName if the name exists;
// otherwise, -1 is returned. Lookup is case-insensitive.
func (dt *DataTable) ColumnIndex(columnName string) int {
column := dt.ColumnByName(columnName)
if column == nil {
return -1
}
return column.Index()
}
// CreateColumn creates a new DataColumn associated with the DataTable.
// Use AddColumn to add the new column to the DataTable.
func (dt *DataTable) CreateColumn(name string, dataType DataTypeEnum, expression string) *DataColumn {
return newDataColumn(dt, name, dataType, expression)
}
// CloneColumn creates a copy of the specified source DataColumn associated with the DataTable.
func (dt *DataTable) CloneColumn(source *DataColumn) *DataColumn {
return dt.CreateColumn(source.Name(), source.Type(), source.Expression())
}
// ColumnCount gets the total number columns defined in the DataTable.
func (dt *DataTable) ColumnCount() int {
return len(dt.columns)
}
// InitRows initializes the internal row collection to the specified length.
// Any existing rows will be deleted.
func (dt *DataTable) InitRows(length int) {
dt.rows = make([]*DataRow, 0, length)
}
// AddRow adds the specified row to the DataTable.
func (dt *DataTable) AddRow(row *DataRow) {
dt.rows = append(dt.rows, row)
}
// Row gets the DataRow at the specified rowIndex if the index is in range;
// otherwise, nil is returned.
func (dt *DataTable) Row(rowIndex int) *DataRow {
if rowIndex < 0 || rowIndex >= len(dt.rows) {
return nil
}
return dt.rows[rowIndex]
}
// RowsWhere returns the rows matching the predicate expression. Set limit parameter
// to -1 for all matching rows.
func (dt *DataTable) RowsWhere(predicate func(*DataRow) bool, limit int) []*DataRow {
matchingRows := make([]*DataRow, 0)
count := 0
for i := 0; i < len(dt.rows); i++ {
dataRow := dt.rows[i]
if dataRow == nil {
continue
}
if predicate(dataRow) {
matchingRows = append(matchingRows, dataRow)
count++
if limit > -1 && count >= limit {
break
}
}
}
return matchingRows
}
// CreateRow creates a new DataRow associated with the DataTable.
// Use AddRow to add the new row to the DataTable.
func (dt *DataTable) CreateRow() *DataRow {
return newDataRow(dt)
}
// CloneRow creates a copy of the specified source DataRow associated with the DataTable.
func (dt *DataTable) CloneRow(source *DataRow) *DataRow {
row := dt.CreateRow()
for i := 0; i < len(dt.columns); i++ {
value, _ := source.Value(i)
row.SetValue(i, value)
}
return row
}
// RowCount gets the total number of rows defined in the DataTable.
func (dt *DataTable) RowCount() int {
return len(dt.rows)
}
// RowValueAsString reads the row record value at the specified columnIndex converted to a string.
// For columnIndex out of range or any other errors, an empty string will be returned.
func (dt *DataTable) RowValueAsString(rowIndex, columnIndex int) string {
row := dt.Row(rowIndex)
if row == nil {
return ""
}
return row.ValueAsString(columnIndex)
}
// RowValueAsStringByName reads the row record value for the specified columnName converted to a string.
// For columnName not found or any other errors, an empty string will be returned.
func (dt *DataTable) RowValueAsStringByName(rowIndex int, columnName string) string {
row := dt.Row(rowIndex)
if row == nil {
return ""
}
return row.ValueAsStringByName(columnName)
}
// String get a representation of the DataTable as a string.
func (dt *DataTable) String() string {
var image strings.Builder
image.WriteString(dt.name)
image.WriteString(" [")
for i := 0; i < len(dt.columns); i++ {
if i > 0 {
image.WriteString(", ")
}
image.WriteString(dt.columns[i].String())
}
image.WriteString("] x ")
image.WriteString(format.Int(len(dt.rows)))
image.WriteString(" rows")
return image.String()
}
// Select returns the rows matching the filterExpression criteria in the specified sort order. The filterExpression parameter
// should be in the syntax of a SQL WHERE expression but should not include the WHERE keyword. The sortOrder parameter defines
// field names, separated by commas, that exist in the DataTable used to order the results. Each field specified in the
// sortOrder can have an ASC or DESC suffix; defaults to ASC when no suffix is provided. When sortOrder is an empty string,
// records will be returned in natural order. Set limit parameter to -1 for all matching rows. When filterExpression is an
// empty string, all records will be returned; any specified sortOrder and limit will still be respected.
func (dt *DataTable) Select(filterExpression string, sortOrder string, limit int) ([]*DataRow, error) {
if len(filterExpression) == 0 {
filterExpression = "True" // Return all records
}
if limit > 0 {
filterExpression = fmt.Sprintf("FILTER TOP %d %s WHERE %s", limit, dt.name, filterExpression)
} else {
filterExpression = fmt.Sprintf("FILTER %s WHERE %s", dt.name, filterExpression)
}
if len(sortOrder) > 0 {
filterExpression = fmt.Sprintf("%s ORDER BY %s", filterExpression, sortOrder)
}
expressionTree, err := GenerateExpressionTree(dt, filterExpression, true)
if err != nil {
return nil, errors.New("failed to parse filter expression, " + err.Error())
}
return expressionTree.Select(dt)
}