/// <summary>
/// Gets the next binary precedence.
/// </summary>
/// <param name="literal">The literal.</param>
/// <returns>System.Int32.</returns>
static int GetNextBinaryPrecedence(this ReadOnlySpan <char> literal)
{
if (!literal.IsNullOrEmpty() && !literal[0].IsExpressionTerminatorChar())
{
literal.ParseJsBinaryOperator(out var binaryOp);
if (binaryOp != null)
{
return(JsTokenUtils.GetBinaryPrecedence(binaryOp.Token));
}
}
return(0);
}
/// <summary>
/// Parses the binary expression.
/// </summary>
/// <param name="literal">The literal.</param>
/// <param name="expr">The expr.</param>
/// <param name="filterExpression">if set to <c>true</c> [filter expression].</param>
/// <returns>ReadOnlySpan<System.Char>.</returns>
/// <exception cref="ServiceStack.Script.SyntaxErrorException">Expected Expression but was {lhs.DebugToken()}</exception>
/// <exception cref="ServiceStack.Script.SyntaxErrorException">Expected binary operator near: {literal.DebugLiteral()}</exception>
/// <exception cref="ServiceStack.Script.SyntaxErrorException">Expected expression near: '{literal.DebugLiteral()}'</exception>
/// <exception cref="ServiceStack.Script.SyntaxErrorException">Expected Expression but was {lhs.DebugToken()}</exception>
public static ReadOnlySpan <char> ParseBinaryExpression(this ReadOnlySpan <char> literal, out JsExpression expr, bool filterExpression)
{
literal = literal.AdvancePastWhitespace();
literal = literal.ParseJsToken(out var lhs, filterExpression: filterExpression);
if (literal.IsNullOrEmpty())
{
expr = lhs as JsExpression ?? throw new SyntaxErrorException($"Expected Expression but was {lhs.DebugToken()}");
}
else
{
literal = literal.ParseJsBinaryOperator(out var op);
if (op == null)
{
throw new SyntaxErrorException($"Expected binary operator near: {literal.DebugLiteral()}");
}
var prec = JsTokenUtils.GetBinaryPrecedence(op.Token);
if (prec > 0 || op == JsAssignment.Operator)
{
literal = literal.ParseJsToken(out JsToken rhs, filterExpression: filterExpression);
var stack = new Stack <JsToken>();
stack.Push(lhs);
stack.Push(op);
stack.Push(rhs);
var precedences = new List <int> {
prec
};
while (true)
{
literal = literal.AdvancePastWhitespace();
if (filterExpression && literal.Length > 2 && literal[0] == '|' && literal[1] != '|')
{
break;
}
prec = literal.GetNextBinaryPrecedence();
if (prec == 0)
{
break;
}
while (stack.Count > 2 && prec <= precedences[precedences.Count - 1])
{
rhs = stack.Pop();
var operand = (JsBinaryOperator)stack.Pop();
precedences.RemoveAt(precedences.Count - 1);
lhs = stack.Pop();
stack.Push(CreateJsExpression(lhs, operand, rhs));
}
literal = literal.ParseJsBinaryOperator(out op);
if (literal.IsNullOrEmpty())
{
throw new SyntaxErrorException($"Expected expression near: '{literal.DebugLiteral()}'");
}
literal = literal.ParseJsToken(out var token, filterExpression: filterExpression);
stack.Push(op);
stack.Push(token);
precedences.Add(prec);
}
var i = stack.Count - 1;
var ret = stack.Pop();
while (stack.Count > 0)
{
op = (JsBinaryOperator)stack.Pop();
lhs = stack.Pop();
ret = CreateJsExpression(lhs, op, ret);
}
expr = (JsExpression)ret;
}
else
{
expr = lhs as JsExpression ?? throw new SyntaxErrorException($"Expected Expression but was {lhs.DebugToken()}");
}
}
return(literal);
}
