175 lines
No EOL
4.2 KiB
Text
175 lines
No EOL
4.2 KiB
Text
//Four Leaf Calculator, by Clover
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//Give credit!!
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Token=function(type,value)
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return {"type": type, "value": value}
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end function
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Lexer=function(text)
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out={}
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out.text=text
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out.pos=0
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out.currChar=out.text[out.pos]
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out.error=function()
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exit("Invalid character")
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end function
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out.advance=function(self)
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self.pos=self.pos+1
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if self.pos > self.text.len-1 then
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self.currChar=null
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else
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self.currChar=self.text[self.pos]
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end if
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end function
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out.skip_ws=function(self)
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while self.currChar and self.currChar == " "
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self.advance
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end while
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end function
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out.integer=function(self)
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result=""
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while self.currChar and typeof(self.currChar.to_int) == "number"
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result=result+self.currChar
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self.advance
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end while
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return result.val
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end function
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out.gnt=function(self)
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while self.currChar
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if self.currChar == " " then
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self.skip_ws
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continue
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end if
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if typeof(self.currChar.to_int) == "number" then
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return Token("INT",self.integer)
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end if
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if self.currChar == "+" then
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self.advance
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return Token("ADD","+")
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end if
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if self.currChar == "-" then
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self.advance
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return Token("SUB","-")
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end if
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if self.currChar == "*" then
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self.advance
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return Token("MUL","*")
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end if
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if self.currChar == "/" then
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self.advance
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return Token("DIV","/")
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end if
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if self.currChar == "^" then
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self.advance
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return Token("EXP","^")
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end if
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if self.currChar == "(" then
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self.advance
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return Token("LPAREN","(")
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end if
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if self.currChar == ")" then
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self.advance
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return Token("RPAREN",")")
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end if
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self.error
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end while
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return Token("EOF",null)
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end function
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return out
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end function
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Interpreter=function(lexer)
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out={}
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out.lexer=lexer
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out.ct=out.lexer.gnt
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out.error=function()
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exit("Invalid syntax")
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end function
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out.eat=function(self,ttype)
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if self.ct.type == ttype then self.ct=self.lexer.gnt else self.error
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end function
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out.factor=function(self)
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token=self.ct
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if token.type == "INT" then
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self.eat("INT")
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return token.value
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else if token.type == "LPAREN" then
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self.eat("LPAREN")
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result=self.expr()
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self.eat("RPAREN")
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return result
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end if
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end function
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out.exp=function(self)
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result=self.factor
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while self.ct.type == "EXP"
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token=self.ct
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self.eat("EXP")
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result=result ^ self.factor()
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end while
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return result
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end function
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out.term=function(self)
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result=self.exp
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while ["MUL","DIV"].indexOf(self.ct.type) != null
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token=self.ct
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if token.type == "MUL" then
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self.eat("MUL")
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result=result*self.exp
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else if token.type == "DIV" then
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self.eat("DIV")
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result=result/self.exp
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end if
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end while
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return result
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end function
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out.expr=function(self)
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result=self.term
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while ["ADD","SUB"].indexOf(self.ct.type) != null
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token=self.ct
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if token.type == "ADD" then
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self.eat("ADD")
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result=result+self.term
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else if token.type == "SUB" then
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self.eat("SUB")
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result=result-self.term
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end if
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end while
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return result
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end function
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return out
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end function
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print("Four Leaf Calculator")
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print("By Clover")
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print
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while 1
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text=user_input("calc> ")
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if not text then continue
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lexer=Lexer(text)
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interp=Interpreter(lexer)
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result=interp.expr
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print(result)
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end while |