/////////////////////////////////////////////又一个
unit m;
interface
uses
Windows, Messages, Math, SysUtils, Classes, Graphics, Controls, Forms, Dialogs,
StdCtrls;
const
Symbol_Mod = 'M';
Symbol_Div = 'D';
Symbol_Shl = 'L';
Symbol_Shr = 'R';
Symbol_Or = 'O';
Symbol_Xor = 'X';
Symbol_And = 'A';
type
TForm1 = class(TForm)
Button1: TButton;
Edit1: TEdit;
Edit2: TEdit;
procedure Button1Click(Sender: TObject);
private
{ Private declarations }
public
{ Public declarations }
end;
var
Form1: TForm1;
implementation
{$R *.DFM}
function ConvertExpression(ExpressionString: PChar): PChar;
var
inputexp: string;
begin
inputexp := ExpressionString;
//convert input expression to recognize expression
if pos('=', inputexp) = 0 then
inputexp := inputexp + '='
else
inputexp := Copy(inputexp, 1, Pos('=', inputexp));
inputexp := UpperCase(inputexp);
inputexp := StringReplace(inputexp, ' ', '', [rfReplaceAll]);
inputexp := StringReplace(inputexp, 'MOD', Symbol_Mod, [rfReplaceAll]);
inputexp := StringReplace(inputexp, 'DIV', Symbol_Div, [rfReplaceAll]);
inputexp := StringReplace(inputexp, 'AND', Symbol_And, [rfReplaceAll]);
inputexp := StringReplace(inputexp, 'XOR', Symbol_Xor, [rfReplaceAll]);
inputexp := StringReplace(inputexp, 'OR', Symbol_Or, [rfReplaceAll]);
inputexp := StringReplace(inputexp, 'SHL', Symbol_Shl, [rfReplaceAll]);
inputexp := StringReplace(inputexp, 'SHR', Symbol_Shr, [rfReplaceAll]);
inputexp := StringReplace(inputexp, '(-', '(0-', [rfReplaceAll]);
if pos('-', inputexp) = 1 then inputexp := '0' + inputexp;
Result := PChar(inputexp);
end;
function ParseExpression(ExpressionString: PChar): extended;
var
nextch: char;
nextchpos, position: word;
inputexp: string;
procedure expression(var ev: extended); forward;
procedure readnextch;
begin
repeat
if inputexp[position] = '=' then
nextch := '='
else
begin
inc(nextchpos);
inc(position);
nextch := inputexp[position];
end;
until (nextch <> ' ') or eoln;
end;
procedure error(ErrorString: string);
begin
MessageDlg('无法识别的语法 : ' + ErrorString, mterror, [mbok], 0);
exit;
end;
procedure number(var nv: extended);
var
radix: longint;
snv: string;
function BinToInt(value: string): integer;
var
i, size: integer;
begin // convert binary number to integer
result := 0;
size := length(value);
for i := size downto 1 do
if copy(value, i, 1) = '1'
then result := result + (1 shl (size - i));
end;
begin
nv := 0;
snv := '';
while nextch in ['0'..'9', 'A'..'F'] do
begin
// nv:=10*nv+ord(nextch)-ord('0');
snv := snv + nextch;
readnextch;
end;
// parse Hex, Bin
if snv <> '' then
if snv[Length(snv)] = 'B'
then
nv := BinToInt(Copy(snv, 1, Length(snv) - 1))
else
if nextch = 'H' then
begin nv := StrToInt('$' + snv);
readnextch;
end
else
nv := StrToInt(snv);
if nextch = '.' then
begin
radix := 10;
readnextch;
while nextch in ['0'..'9'] do
begin
nv := nv + (ord(nextch) - ord('0')) / radix;
radix := radix * 10;
readnextch;
end;
end;
end;
procedure factor(var fv: extended);
var
Symbol: string;
function CalcN(Value: integer): extended;
var
i: integer;
begin
Result := 1;
if Value = 0 then
Exit
else
for i := 1 to Value do
Result := Result * i;
end;
function ParseFunction(var FunctionSymbol: string): boolean;
begin
FunctionSymbol := '';
while not (nextch in ['0'..'9', '.', '(', ')', '+', '-', '*', '/', '=']) do
begin
FunctionSymbol := FunctionSymbol + nextch;
readnextch;
end;
if FunctionSymbol = 'ABS' then
Result := true
else
if FunctionSymbol = 'SIN' then
Result := true
else
if FunctionSymbol = 'COS' then
Result := true
else
if FunctionSymbol = 'TG' then
Result := true
else
if FunctionSymbol = 'TAN' then
Result := true
else
if FunctionSymbol = 'ARCSIN' then
Result := true
else
if FunctionSymbol = 'ARCCOS' then
Result := true
else
if FunctionSymbol = 'ARCTG' then
Result := true
else
if FunctionSymbol = 'ARCTAN' then
Result := true
else
if FunctionSymbol = 'LN' then
Result := true
else
if FunctionSymbol = 'LG' then
Result := true
else
if FunctionSymbol = 'EXP' then
Result := true
else
if FunctionSymbol = 'SQR' then
Result := true
else
if FunctionSymbol = 'SQRT' then
Result := true
else
if FunctionSymbol = 'PI' then
Result := true
else
if FunctionSymbol = 'NOT' then
Result := true
else
if FunctionSymbol = 'N!' then
Result := true
else
if FunctionSymbol = 'E' then
Result := true
else
Result := false;
end;
begin
case nextch of
'0'..'9': number(fv);
'(':
begin
readnextch;
expression(fv);
if nextch = ')'
then
readnextch
else
error(nextch);
end
else
if ParseFunction(Symbol) then
if nextch = '(' then
begin
readnextch;
expression(fv);
if Symbol = 'ABS' then
fv := abs(fv)
else
if Symbol = 'SIN' then
fv := sin(fv)
else
if Symbol = 'COS' then
fv := cos(fv)
else
if Symbol = 'TG' then
fv := tan(fv)
else
if Symbol = 'TAN' then
fv := tan(fv)
else
if Symbol = 'ARCSIN' then
fv := arcsin(fv)
else
if Symbol = 'ARCCOS' then
fv := arccos(fv)
else
if Symbol = 'ARCTG' then
fv := arctan(fv)
else
if Symbol = 'ARCTAN' then
fv := arctan(fv)
else
if Symbol = 'LN' then
fv := ln(fv)
else
if Symbol = 'LG' then
fv := ln(fv) / ln(10)
else
if Symbol = 'EXP' then
fv := exp(fv)
else
if Symbol = 'SQR' then
fv := sqr(fv)
else
if Symbol = 'SQRT' then
fv := sqrt(fv)
else
if Symbol = 'NOT' then
fv := not (Round(fv))
else
if Symbol = 'N!' then
fv := CalcN(Round(fv))
else
error(symbol);
if nextch = ')' then
readnextch
else
error(nextch);
end
else
begin // parse constant
if Symbol = 'PI' then
fv := 3.14159265358979324
else
if Symbol = 'E' then
fv := 2.71828182845904523
else
error(symbol);
end
else
begin error(Symbol);
fv := 1;
end;
end;
end;
procedure Power_(var pv: extended);
var
multiop: char;
fs: extended;
begin
factor(pv);
while nextch in ['^'] do
begin
multiop := nextch;
readnextch;
factor(fs);
case multiop of
'^':
if pv <> 0.0 then
pv := exp(ln(pv) * fs)
else
error(multiop);
end;
end;
end;
procedure term_(var tv: extended);
var
multiop: char;
fs: extended;
begin
Power_(tv);
while nextch in ['*', '/', Symbol_Mod, Symbol_Div, Symbol_And, Symbol_Shl, Symbol_Shr] do
begin
multiop := nextch;
readnextch;
Power_(fs);
case multiop of
'*': tv := tv * fs;
'/':
if fs <> 0.0 then
tv := tv / fs
else
error(multiop);
Symbol_Mod: tv := round(tv) mod round(fs); // prase mod
Symbol_Div: tv := round(tv) div round(fs); // parse div
Symbol_And: tv := round(tv) and round(fs); // parse and
Symbol_Shl: tv := round(tv) shl round(fs); // parse shl
Symbol_Shr: tv := round(tv) shr round(fs); // parse shr
end;
end;
end;
procedure expression(var ev: extended);
var
addop: char;
fs: extended;
begin
term_(ev);
while nextch in ['+', '-', Symbol_Or, Symbol_Xor] do
begin
addop := nextch;
readnextch;
term_(fs);
case addop of
'+': ev := ev + fs;
'-': ev := ev - fs;
Symbol_Or: ev := round(ev) or round(fs); // parse or
Symbol_Xor: ev := round(ev) xor round(fs); // parse xor
end;
end;
end;
begin
inputexp := ConvertExpression(ExpressionString);
if pos('=', inputexp) = 0 then
inputexp := ConvertExpression(ExpressionString);
position := 0;
while inputexp[position] <> '=' do
begin
nextchpos := 0;
readnextch;
expression(result);
end;
end;
function ParseExpressionToStr(ExpressionString: PChar): PChar;
var
ES: string;
begin
ES := ExpressionString;
if pos('=', ES) = 0
then
ES := ES + '='
else
ES := Copy(ES, 1, Pos('=', ES));
ES := ES + FormatFloat('0.000000000000', ParseExpression(ExpressionString));
Result := PChar(ES);
end;
procedure TForm1.Button1Click(Sender: TObject);
begin
Edit1.Text:=ConvertExpression(pchar(Edit1.text));
Edit2.Text:=floattostr(ParseExpression(Pchar(Edit1.text)));
end;
end.