/// <summary>
/// Creates a Geometry using the next token in the stream.
/// </summary>
/// <param name="tokenizer">
/// Tokenizer over a stream of text in Well-known Text
/// format. The next tokens must form a <Geometry Tagged Text>.
/// </param>
/// <returns>Returns a Geometry specified by the next token in the stream.</returns>
/// <remarks>
/// Exception is thrown if the coordinates used to create a Polygon
/// shell and holes do not form closed linestrings, or if an unexpected
/// token is encountered.
/// </remarks>
internal static Geometry ReadGeometryTaggedText(WktStreamTokenizer tokenizer)
{
tokenizer.NextToken();
var type = tokenizer.GetStringValue().ToUpper();
Geometry geometry;
switch (type)
{
case "POINT":
geometry = ReadPointText(tokenizer);
break;
case "LINESTRING":
geometry = ReadLineStringText(tokenizer);
break;
case "MULTILINESTRING":
geometry = ReadMultiLineStringText(tokenizer);
break;
case "POLYGON":
geometry = ReadPolygonText(tokenizer);
break;
case "MULTIPOLYGON":
geometry = ReadMultiPolygonText(tokenizer);
break;
default:
throw new NotImplementedException($"Geometrytype '{type}' is not supported.");
}
return(geometry);
}
/// <summary>
/// Returns the next word in the stream as uppercase text.
/// </summary>
/// <param name="tokenizer">
/// Tokenizer over a stream of text in Well-known Text
/// format. The next token must be a word.
/// </param>
/// <returns>Returns the next word in the stream as uppercase text.</returns>
/// <remarks>
/// Exception is thrown if the next token is not a word.
/// </remarks>
private static string GetNextWord(WktStreamTokenizer tokenizer)
{
var type = tokenizer.NextToken();
var token = tokenizer.GetStringValue();
if (type == TokenType.Number)
{
throw new Exception("Expected a number but got " + token);
}
if (type == TokenType.Word)
{
return(token.ToUpper());
}
if (token == "(")
{
return("(");
}
if (token == ")")
{
return(")");
}
if (token == ",")
{
return(",");
}
throw new Exception("Not a valid symbol in WKT format.");
}
/// <summary>
/// Returns the next ")" or "," in the stream.
/// </summary>
/// <param name="tokenizer">
/// tokenizer over a stream of text in Well-known Text
/// format. The next token must be ")" or ",".
/// </param>
/// <returns>Returns the next ")" or "," in the stream.</returns>
/// <remarks>
/// ParseException is thrown if the next token is not ")" or ",".
/// </remarks>
private static string GetNextCloserOrComma(WktStreamTokenizer tokenizer)
{
tokenizer.NextToken();
var nextWord = tokenizer.GetStringValue();
if (nextWord == "," || nextWord == ")")
{
return(nextWord);
}
throw new Exception("Expected ')' or ',' but encountered '" + nextWord + "'");
}
/// <summary>
/// Returns the next "EMPTY" or "(" in the stream as uppercase text.
/// </summary>
/// <param name="tokenizer">
/// Tokenizer over a stream of text in Well-known Text
/// format. The next token must be "EMPTY" or "(".
/// </param>
/// <returns>
/// the next "EMPTY" or "(" in the stream as uppercase
/// text.
/// </returns>
/// <remarks>
/// ParseException is thrown if the next token is not "EMPTY" or "(".
/// </remarks>
private static string GetNextEmptyOrOpener(WktStreamTokenizer tokenizer)
{
tokenizer.NextToken();
var nextWord = tokenizer.GetStringValue();
if (nextWord == "EMPTY" || nextWord == "(")
{
return(nextWord);
}
throw new Exception("Expected 'EMPTY' or '(' but encountered '" + nextWord + "'");
}
/// <summary>
/// Returns the next number in the stream.
/// </summary>
/// <param name="tokenizer">
/// Tokenizer over a stream of text in Well-known text format. The next token
/// must be a number.
/// </param>
/// <returns>Returns the next number in the stream.</returns>
/// <remarks>
/// ParseException is thrown if the next token is not a number.
/// </remarks>
private static double GetNextNumber(WktStreamTokenizer tokenizer)
{
tokenizer.NextToken();
return(tokenizer.GetNumericValue());
}