/// <summary>
/// end表示字符串最后一个字符的后一个位置
/// </summary>
/// <param name="begin"></param>
/// <param name="end"></param>
/// <returns></returns>
private Expression parse(int begin, int end)
{
if (begin >= end)
{
kernel.IssueError(ErrorType.ExpressionSyntaxError, loc.Offset(begin));
return null;
}
while (isWhiteSpace(expr[begin]))
begin++;
while (isWhiteSpace(expr[end - 1]))
end--;
int currentParenLevel;
bool hasSideParren = true;
while (expr[begin] == '(' && hasSideParren)
{
currentParenLevel = 0;
int currentPos;
for (currentPos = begin; currentPos < end; currentPos++)
{
if (expr[currentPos] == '(') currentParenLevel++;
else if (expr[currentPos] == ')')
{
currentParenLevel--;
if (currentParenLevel == 0)
{
if (currentPos == end - 1)
{
begin++;
end--;
}
else
hasSideParren = false;
break;
}
}
}
if (currentPos == end && currentParenLevel > 0)
{
kernel.IssueError(ErrorType.SingleParen, loc.Offset(begin));
return null;
}
}
currentParenLevel = 0;
OpLevel currentLevel = OpLevel.Null;
OpLevel minLevel = OpLevel.Null;
int minPos = -1;
int minOpLength = 0;
bool findOp = false;
string op = null;
MatchTokenResult matchTokenResult;
//找到当前应处理的操作符
for (int currentPos = begin; currentPos < end; currentPos = matchTokenResult.EndPos)
{
//if (expr[currentPos] == ' ' || expr[currentPos] == '\t' || expr[currentPos] == '\n'
// || Environment.NewLine.IndexOf(expr[currentPos]) != -1)
//{
// op = null;
// continue;
//}
matchTokenResult = MatchToken(currentPos, end);
if (matchTokenResult.TokenType == TokenType.Error)
return null;
if (matchTokenResult.TokenType != TokenType.Operator)
continue;
op = matchTokenResult.Matched;
if (op != "(" && op != ")") findOp = true;
if (op == "(")
{
currentParenLevel++;
continue;
}
else if (op == ")")
{
currentParenLevel--;
continue;
}
else if (currentParenLevel > 0)
{
continue;
}
else if (currentParenLevel < 0)
{
kernel.IssueError(ErrorType.SingleParen, loc.Offset(currentPos));
return null;
}
if (currentParenLevel == 0
&&(
(int)(currentLevel = getOpLevel(op)) < (int)minLevel)
|| ((int)currentLevel == (int)minLevel && op != "=") //=为右结合
)
{
minLevel = currentLevel;
minPos = matchTokenResult.BeginPos;
minOpLength = op.Length;
}
}
if (currentParenLevel != 0)
{
kernel.IssueError(ErrorType.SingleParen, loc.Offset(begin));
return null;
}
if (!findOp) //单个数据
{
string str = expr.Substring(begin, end - begin);
int currentPos = begin;
matchTokenResult = MatchToken(currentPos, end);
switch (matchTokenResult.TokenType)
{
case TokenType.Int:
RightValueExpr intResult = new RightValueExpr();
IntConst intConst = new IntConst();
intConst.Value = int.Parse(matchTokenResult.Matched);
intResult.DataType = DataType.Int;
intResult.RightValue = intConst;
intResult.Location = loc.Offset(begin);
return intResult;
case TokenType.Float:
RightValueExpr floatResult = new RightValueExpr();
FloatConst floatConst = new FloatConst();
floatConst.Value = float.Parse(matchTokenResult.Matched);
floatResult.DataType = DataType.Int;
floatResult.RightValue = floatConst;
floatResult.Location = loc.Offset(begin);
return floatResult;
case TokenType.String:
RightValueExpr strResult = new RightValueExpr();
StringConst strConst = new StringConst();
strConst.Value = matchTokenResult.Matched;
strResult.DataType = DataType.String;
strResult.RightValue = strConst;
strResult.Location = loc.Offset(begin);
return strResult;
case TokenType.Bool:
RightValueExpr boolResult = new RightValueExpr();
BoolConst boolConst = new BoolConst();
boolConst.Value = bool.Parse(matchTokenResult.Matched);
boolResult.DataType = DataType.Bool;
boolResult.RightValue = boolConst;
boolResult.Location = loc.Offset(begin);
return boolResult;
case TokenType.Variable:
VarRef varRef = new VarRef();
varRef.VarName = matchTokenResult.Matched;
LeftValueExpr leftValueResult = new LeftValueExpr();
leftValueResult.DataType = DataType.Unknown;
leftValueResult.Location = loc.Offset(begin);
leftValueResult.LeftValue = varRef;
return leftValueResult;
default:
kernel.IssueError(ErrorType.ExpressionSyntaxError, loc.Offset(begin));
return null;
}
}
Expression left;
Expression right;
matchTokenResult = MatchToken(minPos, end);
op = matchTokenResult.Matched;
left = (begin != minPos) ? parse(begin, minPos) : null; //null表示单目运算符
right = parse(matchTokenResult.EndPos, end);
Location currentLoc = loc.Offset(begin);
if (right == null)
return null;
switch (op)
{
case "=":
if (!(left is LeftValueExpr))
{
kernel.IssueError(ErrorType.NotLeftValue, currentLoc);
return null;
}
AssignExpr assignExpr = new AssignExpr();
assignExpr.LeftExpr = left as LeftValueExpr;
assignExpr.RightExpr = right;
assignExpr.DataType = right.DataType;
assignExpr.Location = currentLoc;
return assignExpr;
case "&&":
return processBinaryLogicExpr(
new AndExpr(),
left, right, currentLoc);
case "||":
return processBinaryLogicExpr(
new OrExpr(),
left, right, currentLoc);
case "==":
return processBinaryCmpExpr(new EquExpr(), left, right, currentLoc);
case "!=":
return processBinaryCmpExpr(new NeqExpr(), left, right, currentLoc);
case ">":
return processBinaryCmpExpr(new GreatExpr(), left, right, currentLoc);
case ">=":
return processBinaryCmpExpr(new GreatEquExpr(), left, right, currentLoc);
case "<":
return processBinaryCmpExpr(new LessExpr(), left, right, currentLoc);
case "<=":
return processBinaryCmpExpr(new LessEquExpr(), left, right, currentLoc);
case "+":
return processBinaryAlgoExpr(new AddExpr(), left, right, currentLoc);
case "-":
if (left == null)
{
NegativeExpr negExpr = new NegativeExpr();
if (right.DataType == DataType.Bool || right.DataType == DataType.String)
{
kernel.IssueError(ErrorType.OprandTypeError, currentLoc);
return null;
}
else if (right.DataType == DataType.Int)
{
negExpr.DataType = DataType.Int;
}
else if (right.DataType == DataType.Float)
{
negExpr.DataType = DataType.Float;
}
else
{
negExpr.DataType = DataType.Unknown;
}
negExpr.Op = right;
negExpr.Location = currentLoc;
return negExpr;
}
else
{
return processBinaryAlgoExpr(new SubExpr(), left, right, currentLoc);
}
case "*":
return processBinaryAlgoExpr(new MulExpr(), left, right, currentLoc);
case "/":
return processBinaryAlgoExpr(new DivExpr(), left, right, currentLoc);
case "^":
return processBinaryAlgoExpr(new PowExpr(), left, right, currentLoc);
case "!":
if (left != null)
{
kernel.IssueError(ErrorType.ExpressionSyntaxError, currentLoc);
return null;
}
else
{
NotExpr notExpr = new NotExpr();
notExpr.DataType = DataType.Bool;
notExpr.Op = right;
notExpr.Location = currentLoc;
return notExpr;
}
}
return null;
}
public void Visit(NegativeExpr negativeExpr, object[] args)
{
negativeExpr.Op.Accept(this);
RightValue v = readRightValue(negativeExpr);
if (v is IntConst)
{
IntConst result = new IntConst();
result.Value = -(v as IntConst).Value;
negativeExpr.RightValue = result;
}
else if (v is FloatConst)
{
FloatConst result = new FloatConst();
result.Value = -(v as FloatConst).Value;
negativeExpr.RightValue = result;
}
else
{
throw new RuntimeException(new Error(ErrorType.OprandTypeError, negativeExpr.Location));
}
}