from genericScanner import *

class LexerError(Exception): pass

#-----------------------------------------------------------------------
#
#               Token
#
#-----------------------------------------------------------------------
class Token:
    """
    A Token object is the kind of thing that the Lexer returns.
    It holds:
    - the text of the token (self.cargo)
    - the type of token that it is
    - the line number and column index where the token starts
    """

    #-------------------------------------------------------------------
    #
    #-------------------------------------------------------------------
    def __init__(self, startChar):
        """
        The constructor of the Token class
        """
        self.cargo     = startChar.cargo

        #----------------------------------------------------------
        # The token picks up information
        # about its location in the sourceText
        #----------------------------------------------------------
        self.sourceText = startChar.sourceText
        self.lineIndex  = startChar.lineIndex
        self.colIndex   = startChar.colIndex

        #----------------------------------------------------------
        # We won't know what kind of token we have until we have
        # finished processing all of the characters in the token.
        # So when we start, the token.type is None (aka null).
        #----------------------------------------------------------
        self.type      = None

    #-------------------------------------------------------------------
    #  return a displayable string representation of the token
    #-------------------------------------------------------------------
    def show(self,showLineNumbers=False,**kwargs):
        """
        align=True shows token type left justified with dot leaders.
        Specify align=False to turn this feature OFF.        
        """
        align = kwargs.get("align",True)
        if align: 
            tokenTypeLen = 12
            space = " "
        else: 
            tokenTypeLen = 0
            space = ""
            
        if showLineNumbers:
            s = str(self.lineIndex).rjust(6) + str(self.colIndex).rjust(4) + "  "
        else:
            s = ""
            
        if self.type == self.cargo: 
            s = s + "Symbol".ljust(tokenTypeLen,".") + ":" + space + self.type
        elif self.type == "Whitespace": 
            s = s + "Whitespace".ljust(tokenTypeLen,".") + ":" + space + repr(self.cargo)
        else:
            s = s + self.type.ljust(tokenTypeLen,".") + ":" + space + self.cargo
        return s
            
    guts = property(show)


    #-------------------------------------------------------------------
    #
    #-------------------------------------------------------------------
    def abort(self,msg):
        lines = self.sourceText.split("\n")
        sourceLine = lines[self.lineIndex]
        raise LexerError("\nIn line "      + str(self.lineIndex + 1)
               + " near column " + str(self.colIndex + 1) + ":\n\n"
               + sourceLine.replace("\t"," ") + "\n"
               + " "* self.colIndex
               + "^\n\n"
               + msg)