/// <summary>
/// Gets a scalar value identified by its key
/// </summary>
/// <param name="parent">Parent node</param>
/// <param name="key">Key of the value</param>
/// <param name="errorMessage">Error message if the key does not exists</param>
/// <returns>Returns the scalar value</returns>
public string GetScalarValue(YamlNode parent, string key, string errorMessage = null)
{
Contract.Requires(parent != null);
Contract.Requires(key != null);
Contract.Ensures(Contract.Result<string>() != null);
try
{
var mapping = (YamlMappingNode)parent;
var pairs = EnumerateNodesOf(mapping);
var keyNode = new YamlScalarNode(key);
foreach (var pair in pairs)
{
if (keyNode.Equals(pair.Key))
{
if (pair.Value is YamlScalarNode)
{
var v = ((YamlScalarNode) pair.Value).Value;
if (v != null)
return v;
}
throw new InvalidSpecificationException(errorMessage ?? String.Format("No value for key {0}", key));
}
}
throw new InvalidSpecificationException(String.Format("Parent has no child with key {0}", key));
}
catch (Exception ex)
{
throw new InvalidSpecificationException(errorMessage ?? ex.Message, ex);
}
}
/// <summary>
/// Gets an optional scalar value identified by its key
/// </summary>
/// <param name="parent">Parent node</param>
/// <param name="key">Key of the value</param>
/// <param name="defaultValue">Default value to be used if the key is not found in parent</param>
/// <returns>Returns either the scalar value read from the parent node, or the default value.</returns>
public string GetOptionalScalarValue(YamlNode parent, string key, string defaultValue)
{
Contract.Requires(parent != null);
Contract.Requires(key != null);
Contract.Ensures(Contract.Result<string>() != null || Contract.Result<string>() == defaultValue);
var mapping = parent as YamlMappingNode;
if (mapping != null)
{
var pairs = EnumerateNodesOf(mapping);
var keyNode = new YamlScalarNode(key);
foreach (var pair in pairs)
{
if (keyNode.Equals(pair.Key) &&
pair.Value is YamlScalarNode)
return ((YamlScalarNode)pair.Value).Value;
}
}
return defaultValue;
}
