/
calculator.go
341 lines (338 loc) · 6.18 KB
/
calculator.go
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package cal
import (
"errors"
"fmt"
"strconv"
"strings"
"text/scanner"
)
func Cal(s string, vars map[string]interface{}) (float64, error) {
items := Parser(s)
var opstack []string
var calstack []float64
for _, item := range items {
switch item {
case "-":
fallthrough
case "+":
fallthrough
case "/":
fallthrough
case "||":
fallthrough
case "&&":
fallthrough
case "!=":
fallthrough
case ">":
fallthrough
case ">=":
fallthrough
case "<":
fallthrough
case "<=":
fallthrough
case "==":
fallthrough
case "*":
{
for {
if checkPeroption(opstack, item) {
rst, err := cal2(calstack,
opstack[len(opstack)-1])
if err != nil {
return 0, err
}
if len(calstack) > 1 {
calstack = calstack[:len(calstack)-2]
} else {
calstack = calstack[:0]
}
calstack = append(calstack, rst)
opstack = opstack[:len(opstack)-1]
} else {
break
}
}
opstack = append(opstack, item)
}
case "(":
{
opstack = append(opstack, item)
}
case ")":
{
for {
if opstack[len(opstack)-1] == "(" {
opstack = opstack[:len(opstack)-1]
break
}
rst, err := cal2(calstack,
opstack[len(opstack)-1])
if err != nil {
return 0, err
}
if len(calstack) > 1 {
calstack = calstack[:len(calstack)-2]
} else {
calstack = calstack[:0]
}
calstack = append(calstack, rst)
opstack = opstack[:len(opstack)-1]
}
}
default:
{
v, ok := vars[item]
if ok {
value := getValue(v)
calstack = append(calstack, value)
} else {
value, err := strconv.ParseFloat(item, 64)
if err == nil {
calstack = append(calstack, value)
continue
}
return 0, errors.New("miss value of " + item)
}
}
}
}
for {
if len(opstack) == 0 || len(calstack) == 1 {
break
}
rst, err := cal2(calstack, opstack[len(opstack)-1])
if err != nil {
return 0, err
}
if len(calstack) > 1 {
calstack = calstack[:len(calstack)-2]
} else {
calstack = calstack[:0]
}
calstack = append(calstack, rst)
opstack = opstack[:len(opstack)-1]
}
if len(calstack) > 1 {
return calstack[0], errors.New("error exp")
}
if len(calstack) == 0 {
return 0, errors.New("nothing to calculate")
}
return calstack[len(calstack)-1], nil
}
func getValue(v interface{}) float64 {
var value float64
switch v.(type) {
case int:
{
d, _ := v.(int)
value = float64(d)
}
case int8:
{
d, _ := v.(int8)
value = float64(d)
}
case int16:
{
d, _ := v.(int16)
value = float64(d)
}
case int32:
{
d, _ := v.(int32)
value = float64(d)
}
case int64:
{
d, _ := v.(int64)
value = float64(d)
}
case uint8:
{
d, _ := v.(uint8)
value = float64(d)
}
case uint16:
{
d, _ := v.(uint16)
value = float64(d)
}
case uint32:
{
d, _ := v.(uint32)
value = float64(d)
}
case uint64:
{
d, _ := v.(uint64)
value = float64(d)
}
case float64:
{
value, _ = v.(float64)
}
case float32:
{
d, _ := v.(float32)
value = float64(d)
}
}
return value
}
func cal2(calstack []float64, op string) (float64, error) {
var exp1 float64
var exp2 float64
switch len(calstack) {
case 1:
{
exp1 = 0
exp2 = calstack[len(calstack)-1]
}
case 0:
{
exp1 = 0
exp2 = 0
}
default:
{
exp1 = calstack[len(calstack)-2]
exp2 = calstack[len(calstack)-1]
}
}
switch op {
case "||":
{
if (exp1 > 0) || (exp2 > 0) {
return 1, nil
} else {
return 0, nil
}
}
case "&&":
{
if (exp1 > 0) && (exp2 > 0) {
return 1, nil
} else {
return 0, nil
}
}
case "==":
{
if exp1 == exp2 {
return 1, nil
} else {
return 0, nil
}
}
case ">=":
{
if exp1 >= exp2 {
return 1, nil
} else {
return 0, nil
}
}
case "<=":
{
if exp1 <= exp2 {
return 1, nil
} else {
return 0, nil
}
}
case "!=":
{
if exp1 != exp2 {
return 1, nil
} else {
return 0, nil
}
}
case ">":
{
if exp1 > exp2 {
return 1, nil
} else {
return 0, nil
}
}
case "<":
{
if exp1 < exp2 {
return 1, nil
} else {
return 0, nil
}
}
case "+":
{
return exp1 + exp2, nil
}
case "-":
{
return exp1 - exp2, nil
}
case "*":
{
return exp1 * exp2, nil
}
case "/":
{
if exp2 == 0 {
return 0, errors.New("Div by zero")
}
return exp1 / exp2, nil
}
}
return 0, nil
}
func checkPeroption(opstack []string, op string) bool {
i := len(opstack)
if i > 0 {
if (opstack[i-1] == "-" || opstack[i-1] == "+" || opstack[i-1] == "*" || opstack[i-1] == "/") && (op == "-" || op == "+") {
return true
}
if (opstack[i-1] == "*" || opstack[i-1] == "/") && (op == "*" || op == "/") {
return true
}
if (opstack[i-1] == "==" || opstack[i-1] == "!=" || opstack[i-1] == ">=" || opstack[i-1] == "<=" || opstack[i-1] == "<" || opstack[i-1] == ">" || opstack[i-1] == "-" || opstack[i-1] == "+" || opstack[i-1] == "*" || opstack[i-1] == "/") && (op == "==" || op == "!=" || op == ">=" || op == "<=" || op == ">" || op == "<") {
return true
}
if (opstack[i-1] == "==" || opstack[i-1] == "!=" || opstack[i-1] == ">=" || opstack[i-1] == "<=" || opstack[i-1] == "<" || opstack[i-1] == ">" || opstack[i-1] == "-" || opstack[i-1] == "+" || opstack[i-1] == "*" || opstack[i-1] == "/" || opstack[i-1] == "&&" || opstack[i-1] == "||") && (op == "&&" || op == "||") {
return true
}
}
return false
}
func Parser(s string) []string {
var items []string
var sc scanner.Scanner
sc.Init(strings.NewReader(s))
var tok rune
for tok != scanner.EOF {
tok = sc.Scan()
item := sc.TokenText()
if tok != scanner.EOF {
i := len(items)
if i > 0 {
if item == "=" && (items[i-1] == "!" || items[i-1] == ">" || items[i-1] == "<" || items[i-1] == "=") {
items[i-1] = fmt.Sprintf("%s%s", items[i-1], item)
continue
}
if item == "|" && (items[i-1]) == "|" {
items[i-1] = fmt.Sprintf("%s%s", items[i-1], item)
continue
}
if item == "&" && (items[i-1]) == "&" {
items[i-1] = fmt.Sprintf("%s%s", items[i-1], item)
continue
}
}
items = append(items, item)
}
}
return items
}