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Fix example

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This commit is contained in:
Alexander Kiryukhin 2022-02-02 22:17:30 +03:00
parent d8d462d3f9
commit 9489f783e5
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GPG key ID: 6DF7A2910D0699E9
3 changed files with 25 additions and 25 deletions
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17
example/math_expression/main.go
View file

@ -1,5 +1,3 @@
// +build example
package main
import (
@ -8,6 +6,13 @@ import (
"github.com/neonxp/unilex"
)
const (
LP unilex.LexType = iota
RP
NUMBER
OPERATOR
)
func main() {
l := unilex.New("10 * (20.0 + 30.0)")
@ -29,13 +34,13 @@ func lexExpression(l *unilex.Lexer) unilex.StateFunc {
switch {
case l.Accept("("):
l.Emit("LP")
l.Emit(LP)
case l.Accept(")"):
l.Emit("RP")
l.Emit(RP)
case unilex.ScanNumber(l):
l.Emit("NUMBER")
l.Emit(NUMBER)
case l.Accept("+-*/^!"):
l.Emit("OPERATOR")
l.Emit(OPERATOR)
case l.Peek() == unilex.EOF:
return nil
default:

30
example/math_expression/rpn.go
View file

@ -1,5 +1,3 @@
// +build example
package main
// Helper functions to convert infix notation to RPN and calculates expression result.
@ -29,36 +27,36 @@ parseLoop:
fmt.Printf("Lexem: %+v\n", ll)
switch {
case ll.Type == "NUMBER", ll.Type == "OPERATOR" && ll.Value == "!":
case ll.Type == NUMBER, ll.Type == OPERATOR && ll.Value == "!":
output = append(output, ll)
case ll.Type == "LP":
case ll.Type == LP:
stack.Push(ll)
case ll.Type == "RP":
case ll.Type == RP:
for {
cl := stack.Pop()
if cl.Type == "LP" {
if cl.Type == LP {
break
}
if cl.Type == unilex.LEOF {
if cl.Type == unilex.LexEOF {
log.Fatalf("No pair for parenthesis at %d", ll.Start)
}
output = append(output, cl)
}
case ll.Type == "OPERATOR":
case ll.Type == OPERATOR:
for {
if stack.Head().Type == "OPERATOR" && (opPriority[stack.Head().Value] > opPriority[ll.Value]) {
if stack.Head().Type == OPERATOR && (opPriority[stack.Head().Value] > opPriority[ll.Value]) {
output = append(output, stack.Pop())
continue
}
break
}
stack.Push(ll)
case ll.Type == unilex.LEOF:
case ll.Type == unilex.LexEOF:
break parseLoop
}
}
for stack.Head().Type != unilex.LEOF {
for stack.Head().Type != unilex.LexEOF {
output = append(output, stack.Pop())
}
@ -68,26 +66,26 @@ parseLoop:
func calculateRPN(rpnLexems []unilex.Lexem) string {
stack := lexemStack{}
for _, op := range rpnLexems {
if op.Type == "NUMBER" {
if op.Type == NUMBER {
stack.Push(op)
} else {
switch op.Value {
case "+":
a1, _ := strconv.ParseFloat(stack.Pop().Value, 64)
a2, _ := strconv.ParseFloat(stack.Pop().Value, 64)
stack.Push(unilex.Lexem{Type: "NUMBER", Value: strconv.FormatFloat(a2+a1, 'f', -1, 64)})
stack.Push(unilex.Lexem{Type: NUMBER, Value: strconv.FormatFloat(a2+a1, 'f', -1, 64)})
case "-":
a1, _ := strconv.ParseFloat(stack.Pop().Value, 64)
a2, _ := strconv.ParseFloat(stack.Pop().Value, 64)
stack.Push(unilex.Lexem{Type: "NUMBER", Value: strconv.FormatFloat(a2-a1, 'f', -1, 64)})
stack.Push(unilex.Lexem{Type: NUMBER, Value: strconv.FormatFloat(a2-a1, 'f', -1, 64)})
case "*":
a1, _ := strconv.ParseFloat(stack.Pop().Value, 64)
a2, _ := strconv.ParseFloat(stack.Pop().Value, 64)
stack.Push(unilex.Lexem{Type: "NUMBER", Value: strconv.FormatFloat(a2*a1, 'f', -1, 64)})
stack.Push(unilex.Lexem{Type: NUMBER, Value: strconv.FormatFloat(a2*a1, 'f', -1, 64)})
case "/":
a1, _ := strconv.ParseFloat(stack.Pop().Value, 64)
a2, _ := strconv.ParseFloat(stack.Pop().Value, 64)
stack.Push(unilex.Lexem{Type: "NUMBER", Value: strconv.FormatFloat(a2/a1, 'f', -1, 64)})
stack.Push(unilex.Lexem{Type: NUMBER, Value: strconv.FormatFloat(a2/a1, 'f', -1, 64)})
}
}
}

3
example/math_expression/stack.go
View file

@ -1,6 +1,3 @@
//go:build example
// +build example
package main
// Simple lexem stack implementation.