private InterpolatedStringInsertSyntax ParseInterpolatedStringInsert()
{
ExpressionSyntax expr;
var commaToken = default(SyntaxToken);
ExpressionSyntax alignmentExpression = null;
var colonToken = default(SyntaxToken);
var formatToken = default(SyntaxToken);
expr = this.ParseExpression();
if (this.CurrentToken.Kind == SyntaxKind.CommaToken)
{
commaToken = this.EatToken(SyntaxKind.CommaToken);
// require the width to be a literal (one token) of the negative of a literal (two tokens)
var minusToken = (this.CurrentToken.Kind == SyntaxKind.MinusToken) ? this.EatToken(SyntaxKind.MinusToken) : null;
var widthToken = this.EatToken(SyntaxKind.NumericLiteralToken);
var widthExpression = SyntaxFactory.LiteralExpression(SyntaxKind.NumericLiteralExpression, widthToken);
alignmentExpression = (minusToken != null) ? (ExpressionSyntax)SyntaxFactory.PrefixUnaryExpression(SyntaxKind.UnaryMinusExpression, minusToken, widthExpression) : widthExpression;
}
if (this.CurrentToken.Kind == SyntaxKind.ColonToken)
{
colonToken = this.EatToken(SyntaxKind.ColonToken);
formatToken = this.EatToken(this.CurrentToken.Kind == SyntaxKind.IdentifierToken ? SyntaxKind.IdentifierToken : SyntaxKind.StringLiteralToken);
}
return(SyntaxFactory.InterpolatedStringInsert(
expr, // expression
commaToken, // ,
alignmentExpression, // -5
colonToken, // :
formatToken)); // N2
}