"""Definition of the ParserSyntaxError raised on parse failure"""
import string
from simpleparse.stt.TextTools.TextTools import countlines
class ParserSyntaxError( SyntaxError ):
"""Sub-class of SyntaxError for use by SimpleParse parsers
Every instance will have the following attributes:
buffer -- pointer to the source buffer
position -- integer position in buffer where error occured or -1
production -- the production which failed
expected -- string (currently taken from grammar) describing
what production/element token failed to match
the following will be calculated in order to display
human-friendly error messages:
line -- ~ text line-number or -1
lineChar -- ~ character on line where parsing failed or -1
"""
buffer = ""
position = -1
line = -1
production = ""
expected = ""
error_message = None
DEFAULTTEMPLATE = """Failed parsing production "%(production)s" @pos %(position)s (~line %(line)s:%(lineChar)s).\nExpected syntax: %(expected)s\nGot text: %(text)s"""
def __str__( self ):
"""Create a string representation of the error"""
if self.error_message:
return '%s: %s'%( self.__class__.__name__, self.messageFormat(self.error_message) )
else:
return '%s: %s'%( self.__class__.__name__, self.messageFormat() )
def messageFormat( self, template=None):
"""Create a default message for this syntax error"""
if template is None:
template = self.DEFAULTTEMPLATE
line, lineChar = self.getLineCoordinate()
variables = {
"production": self.production,
"position": self.position,
"line": line,
"lineChar": lineChar,
"expected": self.expected or "UNKNOWN",
"text": repr(self.buffer[ self.position:self.position+50 ]),
}
return template % variables
def getLineCoordinate( self ):
"""Get (line number, line character) for the error"""
lineChar = string.rfind( self.buffer, '\n', 0, self.position)
if lineChar == -1: # was no \n before the current position
lineChar = self.position
line = 1
else:
line = countlines( self.buffer[:lineChar] )
lineChar = self.position-lineChar
return line, lineChar
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