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context.go
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context.go
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package goql
import (
"fmt"
"sort"
"strconv"
"github.com/3mard/goql/parse"
)
type fieldType int
const (
fieldTypeColumn fieldType = iota
fieldTypeCopy
fieldTypeStaticNumber
fieldTypeStaticString
fieldTypeStaticBool
fieldTypeFunction
fieldTypeParameter // means this is a ? and must fill it from the query parameters
)
type field struct {
order int
name string // TODO : support for alias
typ fieldType
staticStr string // for static column only
staticNum float64
copy int // for duplicated field, copy from another field
argsOrder []int // for function column only, the order of arguments in the fields list
show bool
staticBool bool
paramIdx int // for parameters from query input
}
type context struct {
pkg interface{}
q *parse.Query
table string
definition map[string]columnDef
flds []field
selected map[string]int
where parse.Stack
order int
}
const (
itemColumn parse.ItemType = -999
)
// A hack to handle column, I don't like this kind of hacks but I'm too bored :)
type dummy struct {
typ parse.ItemType
pos int
value string
data int
}
func (d dummy) Type() parse.ItemType {
return d.typ
}
func (d dummy) Pos() int {
return d.pos
}
func (d dummy) Value() string {
return d.value
}
func (d dummy) Data() int {
return d.data
}
func (d dummy) String() string {
return "dummy"
}
func newItem(t parse.ItemType, v string, p int, d int) parse.Item {
return dummy{
typ: t,
pos: p,
value: v,
data: d,
}
}
// execute the query
func execute(c interface{}, src *parse.Query, params ...interface{}) ([]string, [][]Getter, error) {
var err error
ctx := &context{pkg: c, q: src}
err = selectColumn(ctx)
if err != nil {
return nil, nil, err
}
return doQuery(ctx, params...)
}
func getStaticColumn(ctx *context, fl parse.Field, show bool) field {
assertType(fl.Item, parse.ItemNumber, parse.ItemTrue, parse.ItemFalse, parse.ItemLiteral1, parse.ItemQuestionMark)
defer func() {
ctx.order++
}()
name := "static"
var t field
if fl.Item.Type() == parse.ItemLiteral1 {
t = field{
order: ctx.order,
name: name,
show: show,
typ: fieldTypeStaticString,
staticStr: parse.GetTokenString(fl.Item),
}
}
if fl.Item.Type() == parse.ItemNumber {
f, _ := strconv.ParseFloat(fl.Item.Value(), 64)
t = field{
order: ctx.order,
name: name,
show: show,
typ: fieldTypeStaticNumber,
staticNum: f,
}
}
if fl.Item.Type() == parse.ItemTrue || fl.Item.Type() == parse.ItemFalse {
f := fl.Item.Type() == parse.ItemTrue
t = field{
order: ctx.order,
name: name,
show: show,
typ: fieldTypeStaticBool,
staticBool: f,
}
}
if fl.Item.Type() == parse.ItemQuestionMark {
t = field{
order: ctx.order,
name: name,
show: show,
typ: fieldTypeParameter,
paramIdx: fl.Item.Data(),
}
}
return t
}
func getFieldColumn(ctx *context, fl parse.Field, show bool) (field, error) {
if fl.Table != "" && fl.Table != ctx.table {
return field{}, fmt.Errorf("table %s is not in select, join is not supported", fl.Table)
}
_, ok := ctx.definition[fl.Item.Value()]
if !ok {
return field{}, fmt.Errorf("field %s is not available in table %s", fl.Item.Value(), ctx.table)
}
defer func() {
ctx.order++
}()
if o, sel := ctx.selected[fl.Item.Value()]; sel {
// this is already selected, simply use the copy type for it
return field{
order: ctx.order,
name: fl.Item.Value(),
show: show,
typ: fieldTypeCopy,
copy: o,
}, nil
}
ctx.selected[fl.Item.Value()] = ctx.order
return field{
order: ctx.order,
name: fl.Item.Value(),
show: show,
typ: fieldTypeColumn,
}, nil
}
func getFieldStar(ctx *context) []field {
res := make([]field, len(ctx.definition))
for i := range ctx.definition {
// the order in * is based on order in definition, so fix it
f, _ := getFieldColumn(ctx, parse.Field{Item: newItem(parse.ItemAlpha, i, 0, 0)}, true)
f.order = ctx.definition[i].Order()
ctx.selected[f.name] = f.order
res[f.order] = f
}
return res
}
func getFieldFunction(ctx *context, fl parse.Field, show bool) ([]field, error) {
assertType(fl.Item, parse.ItemFunc)
if !hasFunction(fl.Item.Value()) {
return nil, fmt.Errorf("function '%s' is not registered", fl.Item.Value())
}
f := []field{
{
order: ctx.order,
name: fl.Item.Value(),
show: show,
typ: fieldTypeFunction,
},
}
var params []field
ctx.order++
var err error
params, f[0].argsOrder, err = getFields(ctx, false, fl.Parameters...)
if err != nil {
return nil, err
}
return append(f, params...), nil
}
func isStatic(t parse.ItemType) bool {
return t == parse.ItemNumber ||
t == parse.ItemTrue ||
t == parse.ItemFalse ||
t == parse.ItemNull ||
t == parse.ItemLiteral1 ||
t == parse.ItemQuestionMark
}
func getFields(ctx *context, show bool, fls ...parse.Field) ([]field, []int, error) {
var direct []int
var res []field
for i := range fls {
direct = append(direct, ctx.order)
switch {
case fls[i].Item.Type() == parse.ItemWildCard:
if !show {
return nil, nil, fmt.Errorf("invalid * position")
}
res = append(res, getFieldStar(ctx)...)
case isStatic(fls[i].Item.Type()):
res = append(res, getStaticColumn(ctx, fls[i], show))
case fls[i].Item.Type() == parse.ItemFunc:
fs, err := getFieldFunction(ctx, fls[i], show)
if err != nil {
return nil, nil, err
}
res = append(res, fs...)
default:
f, err := getFieldColumn(ctx, fls[i], show)
if err != nil {
return nil, nil, err
}
res = append(res, f)
}
}
return res, direct, nil
}
func getOrderFileds(ctx *context, o ...parse.Order) ([]field, error) {
var res []field
for i := range o {
fs, err := getFieldColumn(ctx, parse.Field{Item: newItem(parse.ItemAlpha, o[i].Field, 0, 0)}, false)
if err != nil {
return nil, err
}
res = append(res, fs)
}
return res, nil
}
func getWhereField(ctx *context) (parse.Stack, []field, error) {
ss := ctx.q.Statement.(*parse.SelectStmt)
var res []field
s := parse.NewStack(0)
// which column are needed in where?
if st := ss.Where; st != nil {
for {
p, err := st.Pop()
if err != nil {
break
}
ts := p
switch p.Type() {
case parse.ItemAlpha, parse.ItemLiteral2:
v := parse.GetTokenString(p)
f, err := getFieldColumn(ctx, parse.Field{Item: newItem(parse.ItemAlpha, v, 0, 0)}, false)
if err != nil {
return nil, nil, err
}
res = append(res, f)
ts = newItem(itemColumn, v, 0, f.order)
case parse.ItemQuestionMark:
res = append(res, field{
order: ctx.order,
name: "static",
show: false,
typ: fieldTypeParameter,
paramIdx: p.Data(),
})
ts = newItem(itemColumn, "static", 0, ctx.order)
ctx.order++
case parse.ItemFunc:
fn := p.(parse.FuncItem)
fs, err := getFieldFunction(ctx, parse.Field{Item: p, Parameters: fn.Parameters()}, false)
if err != nil {
return nil, nil, err
}
res = append(res, fs...)
// function is calculated on fill gaps, then simply we can use the result at the end a static
ts = newItem(itemColumn, fn.Value(), 0, fs[0].order)
}
s.Push(ts)
}
}
return s, res, nil
}
func selectColumn(ctx *context) error {
ss := ctx.q.Statement.(*parse.SelectStmt)
tbl, err := getTable(ss.Table)
if err != nil {
return err
}
ctx.table = ss.Table
ctx.definition = tbl
ctx.order = 0
ctx.selected = make(map[string]int)
ctx.where = parse.NewStack(0)
// fields after select
fl, _, err := getFields(ctx, true, ss.Fields...)
if err != nil {
return err
}
ctx.flds = fl
// order fields
fl, err = getOrderFileds(ctx, ss.Order...)
if err != nil {
return err
}
ctx.flds = append(ctx.flds, fl...)
// where fields
ctx.where, fl, err = getWhereField(ctx)
if err != nil {
return err
}
ctx.flds = append(ctx.flds, fl...)
return nil
}
func filterColumn(ctx *context, items ...Getter) []Getter {
fl := ctx.flds
res := make([]Getter, 0, len(items))
for i := range fl {
if fl[i].show {
res = append(res, items[i])
}
}
return res
}
func fillGaps(ctx *context, res []Getter) error {
fl := ctx.flds
for i := range fl {
switch fl[i].typ {
case fieldTypeCopy:
res[fl[i].order] = res[fl[i].copy]
case fieldTypeStaticNumber:
res[i] = Number{Number: fl[i].staticNum}
case fieldTypeStaticString:
res[i] = String{String: fl[i].staticStr}
case fieldTypeStaticBool:
res[i] = Bool{Bool: fl[i].staticBool}
}
}
var err error
// once more for functions :/ if there is a way to fill it in one loop :/
// TODO : exec this at the getTableFields not after that
// since functions added before its parameter, doing it backward to make sure if a function is argument to another function
// is field before
for i := len(fl) - 1; i > -1; i-- {
if fl[i].typ == fieldTypeFunction {
args := make([]Getter, len(fl[i].argsOrder))
for j, v := range fl[i].argsOrder {
args[j] = res[v]
}
res[fl[i].order], err = executeFunction(fl[i].name, args...)
if err != nil {
return err
}
}
}
return nil
}
func callWhere(where getter, i []Getter) (ok bool, err error) {
defer func() {
if e := recover(); e != nil {
err = fmt.Errorf("error : %v", e)
ok = false
}
}()
return toBool(where(i)), nil
}
func paramToStatic(f *field, p interface{}) {
// See https://golang.org/pkg/database/sql/driver/#Value
switch t := p.(type) {
case bool:
f.typ = fieldTypeStaticBool
f.staticBool = t
case string:
f.typ = fieldTypeStaticString
f.staticStr = t
case []byte:
f.typ = fieldTypeStaticString
f.staticStr = string(t)
case int64:
f.typ = fieldTypeStaticNumber
f.staticNum = float64(t)
case float64:
f.typ = fieldTypeStaticNumber
f.staticNum = t
default:
f.typ = fieldTypeStaticString
f.staticStr = fmt.Sprintf("%T", t)
}
}
func doQuery(ctx *context, params ...interface{}) ([]string, [][]Getter, error) {
res := make(chan []Getter, 3)
ss := ctx.q.Statement.(*parse.SelectStmt)
var all = make([]string, len(ctx.flds))
for i := range ctx.flds {
// only fields are allowed
if ctx.flds[i].typ == fieldTypeColumn {
all[i] = ctx.flds[i].name
}
if ctx.flds[i].typ == fieldTypeParameter {
paramToStatic(&ctx.flds[i], params[ctx.flds[i].paramIdx-1])
}
}
quit := make(chan struct{}, 1)
defer func() {
quit <- struct{}{}
close(quit) // prevent the channel leak.
}()
err := getTableFields(ctx.pkg, ss.Table, res, quit, all...)
if err != nil {
return nil, nil, err
}
where, err := buildFilter(ctx.where)
if err != nil {
return nil, nil, err
}
a := make([][]Getter, 0)
for i := range res {
if err = fillGaps(ctx, i); err != nil {
return nil, nil, err
}
ok, err := callWhere(where, i)
if err != nil {
return nil, nil, err
}
if !ok {
continue
}
a = append(a, filterColumn(ctx, i...))
}
column := make([]string, 0, len(ctx.flds))
for i := range ctx.flds {
if ctx.flds[i].show {
column = append(column, ctx.flds[i].name)
}
}
// sort
s := &sortMe{
data: a,
order: ss.Order,
}
sort.Sort(s)
a = s.data
if ss.Count >= 0 && ss.Start >= 0 {
l := len(a)
if ss.Start >= l {
a = [][]Getter{}
} else if ss.Start+ss.Count >= l {
a = a[ss.Start:] // to the end
} else {
a = a[ss.Start : ss.Start+ss.Count]
}
}
return column, a, nil
}