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rows.go
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230 lines (212 loc) · 5.07 KB
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package sql
import (
"database/sql/driver"
"encoding/json"
"fmt"
"github.com/viant/igo"
"github.com/viant/igo/exec"
iexpr "github.com/viant/igo/exec/expr"
"github.com/viant/sqlparser/expr"
"github.com/viant/structql/node"
"github.com/viant/structql/parser"
"github.com/viant/sqlparser/query"
"github.com/viant/xunsafe"
"gopkg.in/yaml.v3"
"io"
"reflect"
"unsafe"
)
// Rows represents rows driver
type Rows struct {
criteria *iexpr.Bool
scope *igo.Scope
recordSelector *exec.Selector
recordType reflect.Type
mapper *mapper
query *query.Select
resources []*resource
resourceIndex int
zeroRecord []byte
record interface{}
isFalsePredicate bool
}
func (r *Rows) nextResource() bool {
if r.resourceIndex >= len(r.resources) {
return false
}
if r.resourceIndex > 0 {
r.resources[r.resourceIndex].Close()
}
r.resourceIndex++
return r.resourceIndex < len(r.resources)
}
func (r *Rows) resource() *resource {
return r.resources[r.resourceIndex]
}
// Columns returns query columns
func (r *Rows) Columns() []string {
var result []string
if r.query.List.IsStarExpr() {
for i := range r.mapper.byPos {
result = append(result, r.recordType.Field(i).Name)
}
return result
}
for _, column := range r.query.List {
switch actual := column.Expr.(type) {
case *expr.Ident:
result = append(result, actual.Name)
case *expr.Literal:
result = append(result, column.Alias)
case *expr.Call:
result = append(result, column.Alias)
default:
return nil
}
}
return result
}
// Close closes rows
func (r *Rows) Close() error {
for _, res := range r.resources {
if res != nil {
res.Close()
}
}
return nil
}
// Next moves to next row
func (r *Rows) Next(dest []driver.Value) error {
if r.resourceIndex >= len(r.resources) || r.isFalsePredicate {
return io.EOF
}
if len(dest) != len(r.mapper.byPos) {
return fmt.Errorf("expected %v, but had %v", len(r.mapper.byPos), len(dest))
}
res := r.resource()
has, err := res.Next()
if err != nil {
return err
}
if !has {
if r.nextResource() {
has, err = r.resource().Next()
if err != nil {
return err
}
}
}
if !has {
return io.EOF
}
copy(unsafe.Slice((*byte)(xunsafe.AsPointer(r.record)), r.recordType.Size()), r.zeroRecord)
resource := r.resource()
switch resource.format {
case "json":
if err = json.Unmarshal(resource.line, r.record); err != nil {
return err
}
case "yaml":
if err = yaml.Unmarshal(resource.line, r.record); err != nil {
return err
}
}
ptr := xunsafe.AsPointer(r.record)
if r.criteria != nil {
if err := r.criteria.State.SetValue("r", r.record); err != nil {
return err
}
if !r.criteria.Compute() {
return r.Next(dest)
}
}
for i, aField := range r.mapper.byPos {
dest[i] = aField.Value(ptr)
}
if len(r.mapper.values) > 0 {
for i, v := range r.mapper.values {
dest[i] = v
}
}
return nil
}
// hasNext returns true if there is next row to fetch.
func (r *Rows) hasNext() bool {
return false
}
// ColumnTypeScanType returns column scan type
func (r *Rows) ColumnTypeScanType(index int) reflect.Type {
aField, ok := r.mapper.byPos[index]
if !ok {
return nil
}
return aField.Type
}
// ColumnTypeDatabaseTypeName returns column database type name
func (r *Rows) ColumnTypeDatabaseTypeName(index int) string {
rType := r.ColumnTypeScanType(index)
switch rType.Kind() {
case reflect.Int:
return "INT"
case reflect.Float64:
return "DECIMAL"
case reflect.Bool:
return "BOOLEAN"
case reflect.String:
return "STRING"
case reflect.Slice:
switch rType.Elem().Kind() {
case reflect.Int:
return "INTS"
case reflect.Float64:
return "DECIMALS"
case reflect.String:
return "STRINGS"
case reflect.Uint8:
return "BYTES"
}
}
return ""
}
// ColumnTypeNullable returns if column is nullable
func (r *Rows) ColumnTypeNullable(index int) (nullable, ok bool) {
rType := r.ColumnTypeScanType(index)
return rType.Kind() == reflect.Pointer, true
}
func (r *Rows) initCriteria(criteria *expr.Qualify, args []driver.NamedValue) error {
var values = &node.Values{Bindings: &node.Binding{}}
for _, v := range args {
values.Values = append(values.Values, v.Value)
}
scope := igo.NewScope()
r.scope = scope
goExpr, err := parser.AsBinaryGoExpr("r.", criteria, r.mapper.lookup, values)
if err != nil {
return fmt.Errorf("failed to compile criteria: %w", err)
}
for _, group := range values.Bindings.Groups {
if group.InStrings != nil {
var strs []string
for _, v := range values.Values[group.From:group.To] {
strs = append(strs, v.(string))
}
group.InStrings.Set(strs)
scope.RegisterFunc("In"+group.Name, group.InStrings.In)
}
if group.InInts != nil {
var ints []int
for _, v := range values.Values[group.From:group.To] {
ints = append(ints, v.(int))
}
group.InInts.Set(ints)
scope.RegisterFunc("In"+group.Name, group.InInts.In)
}
}
if r.recordSelector, err = scope.DefineVariable("r", r.recordType); err != nil {
return err
}
if r.criteria, err = scope.BoolExpression(goExpr); err != nil {
return err
}
return nil
}