/// <summary>
/// Get the identifier type of token
/// </summary>
private Token GetIdentifierToken()
{
Token token = new Token();
do
{
token.Value += Char.ToUpper(GetSourceChar());
SourceIndex++;
}
while (Char.IsLetterOrDigit(GetSourceChar()) || GetSourceChar().Equals('_'));
token.Type = TokenType.Identifier;
return token;
}
/// <summary>
/// Gets the number type of token
/// </summary>
private Token GetNumberToken()
{
Token token = new Token();
do
{
token.Value += GetSourceChar();
SourceIndex++;
}
while (Char.IsDigit(GetSourceChar()));
token.Type = TokenType.Number;
return token;
}
/// <summary>
/// Reads the next token from the code
/// </summary>
private Token ReadNextToken()
{
//Skip redundant data
SkipWhitespace();
Token nextToken = null;
if (GetSourceChar().Equals('\n'))
{
CurrentLine++;
nextToken = new Token();
nextToken.Type = TokenType.EOL;
nextToken.Line = CurrentLine - 1;
SourceIndex++;
return nextToken;
}
else if (Char.IsLetter(GetSourceChar()))
{
nextToken = GetIdentifierToken();
}
else if (Char.IsDigit(GetSourceChar()))
{
nextToken = GetNumberToken();
}
else if (GetSourceChar().Equals('\"'))
{
nextToken = GetStringToken();
}
else if ("(){}.,;*&[]<>=!+-/?".Contains(GetSourceChar()))
{
nextToken = GetSymbolToken();
}
else
{
Console.WriteLine("Error - undefined token");
}
nextToken.Line = CurrentLine;
return nextToken;
}
/// <summary>
/// Gets the symbol type of token
/// </summary>
private Token GetSymbolToken()
{
Token token = new Token();
token.Value += GetSourceChar();
//In case of <=, >=, == or != we have two characters as token
if ((GetSourceChar().Equals('<') || GetSourceChar().Equals('>') ||
GetSourceChar().Equals('!') || GetSourceChar().Equals('='))
&& GetNextSourceChar().Equals('='))
{
SourceIndex++;
token.Value += GetSourceChar();
}
SourceIndex++;
token.Type = TokenType.Symbol;
return token;
}
/// <summary>
/// Gets the string type of token
/// </summary>
private Token GetStringToken()
{
//Skip the first quote mark
SourceIndex++;
Token token = new Token();
do
{
//Can't EOL in middle of string
if (GetSourceChar().Equals('\n'))
Console.WriteLine("Error - expected ending quotation mark");
token.Value += GetSourceChar();
SourceIndex++;
}
//Scan until end quote mark
while (!GetSourceChar().Equals('\"'));
SourceIndex++;
token.Type = TokenType.String;
return token;
}
/// <summary>
/// Parses all the tokens
/// </summary>
public void ParseProgram()
{
//Last Token must be EOL so add one in case
Token eol = new Token();
eol.Line = Tokens[Tokens.Count - 1].Line + 1;
eol.Type = TokenType.EOL;
eol.Value = "\n";
Tokens.Add(eol);
//Start at the first Token
TokenIndex = 0;
for (int line = 0; line < LineCount && GetCurrentToken() != null; line++)
{
Node currentNode = new Node();
Node currentNodeMarker;
if (!GetCurrentToken().Type.Equals(TokenType.EOL))
{
currentNodeMarker = null;
if (line == LineCount - 1)
{
currentNode = ParseStatement(currentNode, ref currentNodeMarker);
RootNode.InsertFinal(currentNode);
if (currentNodeMarker != null)
RootNode.CurrentNode = currentNodeMarker;
}
else
{
RootNode.Insert("STATEMENTS", ParseStatement(currentNode, ref currentNodeMarker));
if (currentNodeMarker != null)
RootNode.CurrentNode = currentNodeMarker;
}
}
TokenIndex++;
}
RootNode.NullifyEmptyChildren();
}