/// <summary>
/// Construct a new <see cref="Sentence"/> from a string, using the specified <see cref="Glossary"/>.
/// </summary>
/// <param name="inputString">The raw string input by the player.</param>
/// <param name="glossary">The <see cref="Glossary"/> to use when parsing the input string.</param>
/// <param name="errorMessage">Describes any issue that occurred when parsing, else null if parsed successfully.</param>
/// <returns>A new, interpretable <see cref="Sentence"/>, or null if parsing failed.</returns>
/// <exception cref="ArgumentNullException">Thrown if any parameter is null.</exception>
public static Sentence Parse(string inputString, Glossary glossary, out string errorMessage)
{
// PREPARATION -- Argument checking, property/field instantiation.
if (inputString == null)
{
throw new ArgumentNullException(nameof(inputString));
}
if (glossary == null)
{
throw new ArgumentNullException(nameof(glossary));
}
// TOKENIZATION -- Split input string into a list of strings, while removing invalid characters and unnecessary words.
List <Token> tokenList = Tokenize(inputString, glossary, out errorMessage);
if (errorMessage != null)
{
return(null);
}
// PARSING -- Construct a sentence out of tokens by converting them to meaningful nodes and organizing them syntactically.
List <Node> nodeList = glossary.ConvertToNodes(tokenList);
CollectNounModifiers(nodeList);
CollectNouns(nodeList);
// FINISH -- Return new sentence
return(new Sentence(nodeList));
}
/// <summary>
/// Converts a player input string into a list of <see cref="Token"/> objects.
/// </summary>
/// <param name="inputString">The string input by the player.</param>
/// <param name="glossary">The <see cref="Glossary"/> used to normalize and validate the input.</param>
/// <param name="errorMessage">Null if no error occurs, otherwise a string that describes the problem.</param>
/// <returns>A list of <see cref="Token"/> objects, or null if an error occured.</returns>
private static List <Token> Tokenize(string inputString, Glossary glossary, out string errorMessage)
{
// trim and split string by whitespace
string[] wordList = inputString.Trim().Split((char[])null, StringSplitOptions.RemoveEmptyEntries);
// Check for empty / whitespace input
if (wordList.Length == 0)
{
errorMessage = "Speak up, please.";
return(null);
}
// create tokens
List <Token> tokenList = new List <Token>();
foreach (string origWord in wordList)
{
// copy and normalize word
string n = glossary.Normalize(string.Copy(origWord));
// remove invalid chars
StringBuilder strBuilder = new StringBuilder(n);
for (int j = strBuilder.Length - 1; j >= 0; j--)
{
if (glossary.IsInvalidChar(strBuilder[j]))
{
strBuilder.Remove(j, 1);
}
}
string newWord = strBuilder.ToString();
// Make tokens, but not of empty or invalid words
if (!(newWord == String.Empty || glossary.IsInvalidWord(newWord)))
{
tokenList.Add(new Token(origWord, newWord));
}
}
// Check if entire input contained invalid chars / words / whitespace
if (tokenList.Count == 0)
{
errorMessage = "I'm pretty sure that isn't a sentence.";
return(null);
}
// Input passed validation
errorMessage = null;
return(tokenList);
}