forked from proullon/ramsql
/
operator.go
214 lines (177 loc) · 4.8 KB
/
operator.go
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package engine
import (
"fmt"
"github.com/IllidanTwister/ramsql/engine/log"
"github.com/IllidanTwister/ramsql/engine/parser"
"strconv"
"strings"
"time"
)
// Operator compares 2 values and return a boolean
type Operator func(leftValue Value, rightValue Value) bool
// NewOperator initializes the operator matching the Token number
func NewOperator(token int, lexeme string) (Operator, error) {
switch token {
case parser.EqualityToken:
return equalityOperator, nil
case parser.LeftDipleToken:
return lessThanOperator, nil
case parser.RightDipleToken:
return greaterThanOperator, nil
case parser.LessOrEqualToken:
return lessOrEqualOperator, nil
case parser.GreaterOrEqualToken:
return greaterOrEqualOperator, nil
}
return nil, fmt.Errorf("Operator '%s' does not exist", lexeme)
}
func convToDate(t interface{}) (time.Time, error) {
switch t := t.(type) {
default:
log.Debug("convToDate> unexpected type %T\n", t)
return time.Time{}, fmt.Errorf("unexpected internal type %T", t)
case string:
d, err := parser.ParseDate(string(t))
if err != nil {
return time.Time{}, fmt.Errorf("cannot parse date %v", t)
}
return *d, nil
}
}
func convToFloat(t interface{}) (float64, error) {
switch t := t.(type) {
default:
log.Debug("convToFloat> unexpected type %T\n", t)
return 0, fmt.Errorf("unexpected internal type %T", t)
case float64:
return float64(t), nil
case int64:
return float64(int64(t)), nil
case int:
return float64(int(t)), nil
case string:
return strconv.ParseFloat(string(t), 64)
}
}
func greaterThanOperator(leftValue Value, rightValue Value) bool {
log.Debug("GreaterThanOperator")
var left, right float64
var err error
var rvalue interface{}
if rightValue.v != nil {
rvalue = rightValue.v
} else {
rvalue = rightValue.lexeme
}
var leftDate time.Time
var isDate bool
left, err = convToFloat(leftValue.v)
if err != nil {
leftDate, err = convToDate(leftValue.v)
if err != nil {
log.Debug("GreaterThanOperator> %s\n", err)
return false
}
isDate = true
}
if !isDate {
right, err = convToFloat(rvalue)
if err != nil {
log.Debug("GreaterThanOperator> %s\n", err)
return false
}
return left > right
}
rightDate, err := convToDate(rvalue)
if err != nil {
log.Debug("GreaterThanOperator> %s\n", err)
return false
}
return leftDate.After(rightDate)
}
func lessOrEqualOperator(leftValue Value, rightValue Value) bool {
return lessThanOperator(leftValue, rightValue) || equalityOperator(leftValue, rightValue)
}
func greaterOrEqualOperator(leftValue Value, rightValue Value) bool {
return greaterThanOperator(leftValue, rightValue) || equalityOperator(leftValue, rightValue)
}
func lessThanOperator(leftValue Value, rightValue Value) bool {
log.Debug("LessThanOperator")
var left, right float64
var err error
var rvalue interface{}
if rightValue.v != nil {
rvalue = rightValue.v
} else {
rvalue = rightValue.lexeme
}
var leftDate time.Time
var isDate bool
left, err = convToFloat(leftValue.v)
if err != nil {
leftDate, err = convToDate(leftValue.v)
if err != nil {
log.Debug("LessThanOperator> %s\n", err)
return false
}
isDate = true
}
if !isDate {
right, err = convToFloat(rvalue)
if err != nil {
log.Debug("LessThanOperator> %s\n", err)
return false
}
return left < right
}
rightDate, err := convToDate(rvalue)
if err != nil {
log.Debug("LessThanOperator> %s\n", err)
return false
}
return leftDate.Before(rightDate)
}
// EqualityOperator checks if given value are equal
func equalityOperator(leftValue Value, rightValue Value) bool {
return equalityValue(leftValue.v, rightValue.lexeme)
}
// TrueOperator always returns true
func TrueOperator(leftValue Value, rightValue Value) bool {
return true
}
func inOperator(leftValue Value, rightValue Value) bool {
// Right value should be a slice of string
values, ok := rightValue.v.([]string)
if !ok {
log.Debug("InOperator: rightValue.v is not a []string !")
return false
}
for i := range values {
log.Debug("InOperator: Testing %v against %s", leftValue.v, values[i])
if equalityValue(leftValue.v, values[i]) {
return true
}
}
return false
}
func equalityValue(value interface{}, lexeme string) bool {
if fmt.Sprintf("%v", value) == lexeme {
return true
}
if strings.EqualFold(lexeme, "false") && fmt.Sprintf("%v", value) == "0" {
return true
} else if strings.EqualFold(lexeme, "true") && fmt.Sprintf("%v", value) == "1" {
return true
} else if strings.EqualFold(fmt.Sprintf("%v", value), "false") && lexeme == "0" {
return true
} else if strings.EqualFold(fmt.Sprintf("%v", value), "true") && lexeme == "1" {
return true
}
return false
}
func isNullOperator(leftValue Value, rightValue Value) bool {
return leftValue.v == nil
}
func isNotNullOperator(leftValue Value, rightValue Value) bool {
return leftValue.v != nil
}