improvement: [storage] move data,lib,ad into a struct

The following fields of Storage have been moved to a new struct

- Data array
- Library map
- Active Document index

Author: Christos Kotsis

db/sql.go

@@ -12,8 +12,8 @@ import (
 
 // SQL is the core struct for working with maps.
 type SQL struct {
+	v1.Cache
 	Query v2.Cache
-	Cache v1.Cache
 }
 
 // NewSQLFactory creates a new empty SQL

db/state.go

@@ -0,0 +1,207 @@
+package db
+
+import (
+	"fmt"
+	"strings"
+
+	e "github.com/ulfox/dby/errors"
+)
+
+const (
+	ire = "index error"
+)
+
+// state struct used by dby storage
+type state struct {
+	data, buffer []interface{}
+	lib          map[string]int
+	ad           int
+}
+
+// newStateFactory for creating a new v3 State
+func newStateFactory() *state {
+	s := state{
+		data:   make([]interface{}, 0),
+		buffer: make([]interface{}, 0),
+		lib:    make(map[string]int),
+	}
+	return &s
+}
+
+// Clear for clearing the v3 state
+func (c *state) Clear() {
+	c.data, c.buffer, c.lib = nil, nil, nil
+
+	c.data = make([]interface{}, 0)
+	c.buffer = make([]interface{}, 0)
+	c.lib = make(map[string]int)
+}
+
+// SetAD for setting new Active Document index
+func (c *state) SetAD(i int) error {
+	if err := c.IndexInRange(i); err != nil {
+		return wrapErr(err)
+	}
+	c.ad = i
+	return nil
+}
+
+// GetAD returns the current active document index
+func (c *state) GetAD() int {
+	return c.ad
+}
+
+// PushData for appending data to the data array
+func (c *state) PushData(d interface{}) {
+	c.data = append(c.data, d)
+}
+
+// PushBuffer for appending data to the buffer array
+func (c *state) PushBuffer(d interface{}) {
+	c.buffer = append(c.buffer, d)
+}
+
+// GetAllData returns the data array
+func (c *state) GetAllData() []interface{} {
+	return c.data
+}
+
+// GetAllBuffer returns the buffer array
+func (c *state) GetAllBuffer() []interface{} {
+	return c.buffer
+}
+
+// GetData returns the data in the c.ad index from the data array
+func (c *state) GetData() interface{} {
+	data, _ := c.GetDataFromIndex(c.GetAD())
+	return data
+}
+
+// GetDataFromIndex returns the i'th element from the data array
+func (c *state) GetDataFromIndex(i int) (interface{}, error) {
+	if err := c.IndexInRange(i); err != nil {
+		return nil, wrapErr(err)
+	}
+	return c.data[i], nil
+}
+
+// SetData sets to input value the data in the c.ad index from the data array
+func (c *state) SetData(v interface{}) error {
+	return c.SetDataFromIndex(v, c.GetAD())
+}
+
+// SetDataFromIndex sets to input value the i'th element from the data array
+func (c *state) SetDataFromIndex(v interface{}, i int) error {
+	if err := c.IndexInRange(i); err != nil {
+		return wrapErr(err)
+	}
+	c.data[i] = v
+	return nil
+}
+
+// GetBufferFromIndex returns the i'th element from the buffer array
+func (c *state) GetBufferFromIndex(i int) (interface{}, error) {
+	if err := c.IndexInRange(i); err != nil {
+		return nil, wrapErr(err)
+	}
+	return c.data[i], nil
+}
+
+// IndexInRange check if index is within data array range
+func (c *state) IndexInRange(i int) error {
+	if len(c.data)-1 >= i {
+		return nil
+	}
+	return fmt.Errorf(ire)
+}
+
+// Lib returns the lib map
+func (c *state) Lib() map[string]int {
+	return c.lib
+}
+
+// AddDoc for adding a document to the lib map
+func (c *state) AddDoc(k string, i int) error {
+	if err := c.IndexInRange(i); err != nil {
+		return wrapErr(err)
+	}
+	c.lib[k] = i
+	return nil
+}
+
+// LibIndex returns the index for a given doc name
+func (c *state) LibIndex(doc string) (int, bool) {
+	i, exists := c.lib[strings.ToLower(doc)]
+	return i, exists
+}
+
+// RemoveDocName removes a doc from the lib
+func (c *state) RemoveDocName(i int) error {
+	if err := c.IndexInRange(i); err != nil {
+		return wrapErr(err)
+	}
+	for k, v := range c.lib {
+		if v == i {
+			delete(c.lib, k)
+		}
+	}
+
+	return nil
+}
+
+// DeleteData for deleting the i'th element from the data array
+func (c *state) DeleteData(i int) error {
+	if err := c.IndexInRange(i); err != nil {
+		return wrapErr(err)
+	}
+
+	if err := c.RemoveDocName(i); err != nil {
+		return e.WrapErr(err)
+	}
+
+	c.data[i] = nil
+	c.data = append(c.data[:i], c.data[i+1:]...)
+
+	if c.ad == i {
+		if c.ad > 0 {
+			c.ad = c.ad - 1
+		} else {
+			c.ad = 0
+		}
+	}
+
+	return nil
+}
+
+// CopyBufferToData for copying buffer array over data array
+func (c *state) CopyBufferToData() {
+	copy(c.data, c.buffer)
+}
+
+// UnsetDataArray for deleting all data. This sets data = nil
+func (c *state) UnsetDataArray() {
+	c.data = nil
+}
+
+// DeleteAllData calls PurgeAllData first and then creates a new empty array
+func (c *state) DeleteAllData() {
+	c.UnsetDataArray()
+	c.data = make([]interface{}, 0)
+}
+
+// UnsetBufferArray This sets buffer = nil
+func (c *state) UnsetBufferArray() {
+	c.buffer = nil
+}
+
+// DeleteBuffer deletes the data from the buffer array
+func (c *state) DeleteBuffer() {
+	c.UnsetBufferArray()
+	c.buffer = append(c.buffer, 0)
+}
+
+// ClearLib removes all keys from the lib map
+func (c *state) ClearLib() {
+	c.lib = nil
+	c.lib = make(map[string]int)
+}