internal static bool IsExpression(string expression)
{
if (string.IsNullOrEmpty(expression))
{
return(false);
}
var stream = new ExpressionStream(expression);
return(stream.Start() && !stream.Start() && stream.SkipToEnd());
}
/// <summary>
/// Tokenize an expression.
/// </summary>
/// <param name="expression">The expression.</param>
/// <returns>A stream of tokens representing the expression.</returns>
/// <example>
/// [parameters('vnetName')]
/// [concat('route-', parameters('subnets')[copyIndex('routeIndex')].name)]
/// [concat(split(parameters('addressPrefix')[0], '/')[0], '/27')]
/// </example>
internal static TokenStream Parse(string expression)
{
var output = new TokenStream();
if (string.IsNullOrEmpty(expression))
{
return(output);
}
var stream = new ExpressionStream(expression);
var processed = false;
stream.Start();
while (!stream.End())
{
processed = false;
if (stream.TryElement(out string element))
{
stream.Separator();
if (int.TryParse(element, out int numeric))
{
output.Numeric(numeric);
}
else
{
output.Function(element);
Function(stream, output);
}
processed = true;
}
if (Index(stream, output))
{
stream.Separator();
processed = true;
}
if (stream.CaptureProperty(out string propertyName))
{
output.Property(propertyName);
stream.Separator();
processed = true;
}
if (stream.CaptureString(out string literal))
{
output.String(literal);
stream.Separator();
processed = true;
}
if (!processed)
{
throw new ExpressionParseException(expression, string.Format(Thread.CurrentThread.CurrentCulture, PSRuleResources.ExpressionInvalid, expression));
}
}
output.MoveTo(0);
return(output);
}
