/
apply.go
239 lines (233 loc) · 4.82 KB
/
apply.go
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package apply
import (
// we also can use
// stack "algorithm/linear-list/stack/seq"
stack "algorithm/linear-list/stack/linked"
"bytes"
"errors"
"strconv"
"fmt"
"strings"
)
// notice: suffix exp don't make sure the expression is legal
const (
//raw text
RawText = iota
//number like 1,2,...
RawNumber
// + -
OperandPrimary
// * / %
OperandMedium
// (
OperandLeftParentheses
// )
OperandRightParentheses
)
var (
MissingOperandNumber = errors.New("MissingOperandNumber")
MissingOperand = errors.New("MissingOperand")
InvalidOperandNumber = errors.New("InvalidOperandNumber")
InvalidOperand = errors.New("InvalidOperand")
DivideZero = errors.New("DivideZero")
)
type SuffixExp = *suffixExp
type suffixExp struct {
*bytes.Buffer
}
type OperandWithLevel struct {
operand string
level int
}
func NewSuffixExp(str string) (se SuffixExp) {
se = &suffixExp {
Buffer: new(bytes.Buffer),
}
se.parseSuffixExp(str)
return se
}
func (se SuffixExp) popWithLevel(st stack.Stack,text string,level int) {
switch level {
case OperandMedium:
se.WriteString(" ")
if !st.IsEmpty() {
ti, _ := st.Top()
top := ti.(OperandWithLevel)
if top.level == OperandMedium {
se.WriteString(top.operand)
_, _ = st.Pop()
se.popWithLevel(st, text, level)
return
}
}
st.Push(OperandWithLevel {
operand: text,
level: level,
})
case OperandPrimary:
se.WriteString(" ")
if !st.IsEmpty() {
ti, _ := st.Top()
top := ti.(OperandWithLevel)
if top.level == OperandPrimary || top.level == OperandMedium {
se.WriteString(top.operand)
_, _ = st.Pop()
se.popWithLevel(st, text, level)
return
}
}
st.Push(OperandWithLevel {
operand: text,
level: level,
})
case OperandLeftParentheses:
st.Push(OperandWithLevel {
operand: text,
level: level,
})
case OperandRightParentheses:
se.WriteString(" ")
for ; !st.IsEmpty(); {
ti, _ := st.Top()
top := ti.(OperandWithLevel)
if top.level == OperandLeftParentheses {
_, _ = st.Pop()
return
}
se.WriteString(top.operand)
_, _ = st.Pop()
}
case RawNumber:
se.WriteString(text)
// notice: may be need be modified
case RawText:
se.WriteString(text)
default:
// do nothing
}
}
func (se SuffixExp) parseSuffixExp(exp string) {
operands := stack.New()
for _, r := range exp {
s := string(r)
switch s {
case "*", "/", "%":
se.popWithLevel(operands, s, OperandMedium)
case "-", "+":
se.popWithLevel(operands, s, OperandPrimary)
case "(":
se.popWithLevel(operands, s, OperandLeftParentheses)
case ")":
se.popWithLevel(operands, s, OperandRightParentheses)
// now is ignore the number and dispatch to RawText
default:
se.popWithLevel(operands, s, RawText)
}
}
for ; !operands.IsEmpty(); {
ti, _ := operands.Pop()
top := ti.(OperandWithLevel)
se.WriteString(" ")
se.WriteString(top.operand)
}
buff := bytes.TrimSpace(se.Bytes())
se.Reset()
se.Write(buff)
}
func eval(st stack.Stack, op string) (value float64, err error) {
var left, right float64
if !st.IsEmpty() {
r, _ := st.Pop()
right = r.(float64)
} else {
return 0.0, MissingOperandNumber
}
if !st.IsEmpty() {
l, _ := st.Pop()
left = l.(float64)
} else {
return 0.0, MissingOperandNumber
}
switch op {
case "*":
return left * right, nil
case "/":
if right == 0.0 {
return 0.0, DivideZero
}
return left / right, nil
case "%":
return float64(int64(left) % int64(right)), nil
case "+":
return left + right, nil
case "-":
return left - right, nil
default:
return 0.0, InvalidOperand
}
}
// now is supported by number
func (se SuffixExp) EvalSuffixExp() (value float64, err error) {
numbers := stack.New()
splited := bytes.Split(se.Bytes(), []byte(" "))
for _ , operand := range splited {
if bytes.ContainsAny(operand, "+-*/%") {
v, err := eval(numbers, string(operand))
if err != nil {
return 0.0, err
}
numbers.Push(v)
} else {
v, err := strconv.ParseFloat(string(operand), 64)
if err != nil {
fmt.Println(err)
fmt.Println(string(operand))
return 0.0, InvalidOperandNumber
}
numbers.Push(v)
}
}
if numbers.Length() != 1 {
return 0.0, MissingOperand
} else {
v, _ := numbers.Pop()
return v.(float64), nil
}
}
// judge whether is matched ()[]{}
func IsMatchedParentheses(checked string) bool {
st := stack.New();
matched := func(s string, e string) (bool) {
switch s {
case "(":
return e == ")"
case "[":
return e == "]"
case "{":
return e == "}"
default:
return false
}
}
for _, r := range checked {
s := string(r)
if strings.ContainsAny(s, "([{") {
st.Push(r)
} else if strings.ContainsAny(s, ")]}") {
if !st.IsEmpty() {
ti, _ := st.Pop()
top := string(ti.(rune))
if !matched(top, s) {
return false
}
} else {
return false
}
}
}
if st.IsEmpty() {
return true
} else {
return false
}
}