private static string FormsOf(string text, FormsOfType type)
{
if (IsComplexExpression(text))
{
return(text);
}
if (text[text.Length - 2] == '*')
{
return(text);
}
switch (type)
{
case FormsOfType.None:
return(text);
case FormsOfType.Inflectional:
return($"FORMSOF(INFLECTIONAL, {text})");
case FormsOfType.Thesaurus:
return($"FORMSOF(THESAURUS, {text})");
case FormsOfType.Both:
return($"(FORMSOF(INFLECTIONAL, {text}) OR FORMSOF(THESAURUS, {text}))");
default:
throw new ParsingException("Unknown FormsOfType.", ErrorKind.UnknownFormsOfType);
}
}
private static void ProcessOr(Stack <string> stack, FormsOfType type)
{
var o2 = stack.Pop();
var o1 = stack.Pop();
var result = $"({FormsOf(o1, type)} OR {FormsOf(o2, type)})";
stack.Push(result);
}
/// <summary>
/// Compiles a given postfix notation expression into a CONTAINSTABLE search condition.
/// </summary>
/// <param name="searchExpression">The input search expression.</param>
/// <param name="type">The FORMSOF type to generate.</param>
/// <returns>The CONTAINSTABLE search condition.</returns>
public static string Translate(string searchExpression, FormsOfType type = FormsOfType.Both)
{
if (searchExpression == null)
{
throw new ArgumentNullException(nameof(searchExpression), "String cannot be null.");
}
var lexemes = Lexer.Tokenize(searchExpression);
if (lexemes.Length == 0)
{
throw new ParsingException("The tokenized search expression contains no lexical elements.", ErrorKind.InvalidEmptyExpression);
}
lexemes = FixAndKeywordCommonIssuesForUserFriendliness(lexemes);
var postfixNotation = Parser.GetPostfixNotation(lexemes);
postfixNotation = FixApostrophesForUserFriendliness(postfixNotation);
var translation = CodeGenerator.Generate(postfixNotation, type);
return(translation);
}
/// <summary>
/// Generates CONTAINSTABLE search condition code for a given postfix notation expression.
/// </summary>
/// <param name="postfixNotation">The input postfix notation.</param>
/// <param name="type">The FORMSOF type to generate.</param>
/// <returns>The CONTAINSTABLE search condition.</returns>
public static string Generate(LexicalElement[] postfixNotation, FormsOfType type = FormsOfType.Both)
{
if (postfixNotation == null)
{
throw new ArgumentNullException(nameof(postfixNotation), "Postfix notation array cannot be null.");
}
if (postfixNotation.Length == 0)
{
throw new ParsingException("Invalid empty expression.", ErrorKind.InvalidEmptyExpression);
}
var stack = new Stack <string>(postfixNotation.Length);
foreach (var currentElement in postfixNotation)
{
if (currentElement.Type.IsOperator())
{
var operandCount = currentElement.Type.GetOperandCount();
if (stack.Count < operandCount)
{
throw new ParsingException(
$"Missing operand for operator. Expected {operandCount} operands, found {stack.Count} potential operands",
currentElement, ErrorKind.MissingOperand);
}
switch (currentElement.Type)
{
case LexicalElementType.And:
ProcessAnd(stack, type);
break;
case LexicalElementType.Not:
ProcessNot(stack, type);
break;
case LexicalElementType.Or:
ProcessOr(stack, type);
break;
case LexicalElementType.Near:
ProcessNear(stack, currentElement, false);
break;
case LexicalElementType.OrderedNear:
ProcessNear(stack, currentElement, true);
break;
}
}
else
{
if (currentElement.Type != LexicalElementType.Term)
{
throw new ParsingException("Expected \"Term\" token type. Found unexpected token",
currentElement, ErrorKind.UnexpectedTokenType);
}
stack.Push(Quote(currentElement.Text));
}
}
if (stack.Count != 1)
{
throw new ParsingException($"Evaluation failed. The stack contains {stack.Count} items.",
ErrorKind.StackHasMoreOrLessThanOneItem);
}
var result = stack.Pop();
result = FormsOf(result, type);
return(result);
}