tdb/queryop.go

package tdb

import (
	"bytes"
	"errors"
	"fmt"

	// "sort"

	"git.keganmyers.com/terribleplan/tdb/stringy"

	bolt "go.etcd.io/bbolt"
)

type queryOpCreator func(*table, string, interface{}) (queryOpish, error)

var queryOps map[string]queryOpCreator = map[string]queryOpCreator{
	"=": createEqualQueryOp,
	// "in": createInQueryOp,
}

func createQueryOp(table *table, field, opType string, value interface{}) (queryOpish, error) {
	create, ok := queryOps[opType]
	if !ok {
		return nil, fmt.Errorf("Unknown query operation '%s'", opType)
	}

	op, err := create(table, field, value)
	if err != nil {
		table.debugLogf("Failed creating query for '%s' on table '%s'", opType, table.name)
		return nil, err
	}

	err = op.valid()
	if err != nil {
		table.debugLogf("Unable to form valid query for '%s' on table '%s'", opType, table.name)
		return nil, err
	}

	return op, nil
}

type queryOpish interface {
	rawIterable
	Iterable
	match(v dbPtrValue) bool
	indexed() bool
	valid() error
	String() string
}

type queryOp struct {
	table *table
	field dbField
	value []byte
	index indexish
}

func createCommonQueryOp(table *table, field string, value interface{}) (*queryOp, error) {
	index, ok := table.indicies[field]
	if ok {
		table.debugLogf("[query] found index for field '%s'", field)
	} else {
		table.debugLogf("[query] did not find index for field '%s'", field)
		if len(table.indicies) == 0 {
			table.debugLog("[query] (0 indicies found)")
		} else {
			for name, _ := range table.indicies {
				table.debugLogf("[query] '%s' is indexed", name)
			}
		}
	}

	q := &queryOp{
		table: table,
		field: table.t.NamedField(field),
		value: []byte(stringy.ToStringOrPanic(value)),
		index: index,
	}
	return q, nil
}

// re-used for queryOpEqual
func (op *queryOp) indexed() bool {
	return op.index != nil
}

type queryOpEqual queryOp

func createEqualQueryOp(table *table, field string, value interface{}) (queryOpish, error) {
	qo, err := createCommonQueryOp(table, field, value)
	if err != nil {
		return nil, err
	}

	qoe := queryOpEqual(*qo)
	return &qoe, nil
}

func (op *queryOpEqual) String() string {
	return fmt.Sprintf("%s = %s", op.field.Name, op.value)
}

func (op *queryOpEqual) indexed() bool {
	indexed := op.index != nil
	op.table.debugLogf("[query] Table '%s'.'%s' indexed() -> %t", op.table.name, op.field.Name, indexed)
	return indexed
}

func (op *queryOpEqual) valid() error {
	return nil
}

func (op *queryOpEqual) match(pv dbPtrValue) bool {
	return bytes.Equal([]byte(stringy.ValToStringOrPanic(pv.dangerous_Field(op.field))), op.value)
}

func (op *queryOpEqual) rawIterateKeys(i keyIteratorWithBucket, txs ...*Tx) error {
	if op.index == nil {
		return errors.New("This method is only applicable if the op is indexed")
	}

	return op.table.db.readTxHelper(func(tx *Tx) error {
		db := op.table.bucket(tx)

		return op.index.iteratePrefixed(tx, op.value, func(key []byte) (IterationSignal, error) {
			return i(key, db)
		})
	}, txs...)
}

func (op *queryOpEqual) IterateKeys(i KeyIterator, txs ...*Tx) error {
	return op.rawIterateKeys(func(k []byte, _ *bolt.Bucket) (IterationSignal, error) {
		return i(k)
	}, txs...)
}

func (op *queryOpEqual) Iterate(i Iterator, txs ...*Tx) error {
	return op.rawIterateKeys(func(k []byte, b *bolt.Bucket) (IterationSignal, error) {
		v, err := op.table.getWithinTx(b, k)
		if err != nil {
			op.table.debugLogf("[query] Encountered error while iterating (%s)", err)
			return StopIteration, err
		}
		return i(v)
	}, txs...)
}

func (op *queryOpEqual) iterateRaw(i rawIterator, txs ...*Tx) error {
	return op.rawIterateKeys(func(k []byte, b *bolt.Bucket) (IterationSignal, error) {
		v, err := op.table.getValWithinTx(b, k)
		if err != nil {
			op.table.debugLogf("[query] Encountered error while iterating (%s)", err)
			return StopIteration, err
		}
		return i(v)
	}, txs...)
}