def main():
import sys, PgenParser, pprint, DFAParser
# ____________________________________________________________
# Generate a test parser
grammarST = PgenParser.parseFile("Grammar")
pgenObj = PyPgen()
grammarObj = pgenObj(grammarST)
if "-py" in sys.argv:
print "# %s" % ("_" * 70)
print "# This was automatically generated by PyPgen."
print "# Hack at your own risk."
print
print "grammarObj =",
pprint.pprint(grammarObj)
if "-i" in sys.argv:
# __________________________________________________
# Parse some input
if len(sys.argv) > 1:
inputFile = sys.argv[1]
fileObj = open(inputFile)
else:
inputFile = "<stdin>"
fileObj = sys.stdin
tokenizer = StdTokenizer.StdTokenizer().tokenize(fileObj)
parseTree = DFAParser.parsetok(tokenizer, grammarObj, 257)
fileObj.close()
# __________________________________________________
# Show the result
if __BASIL__:
from basil.visuals.TreeBox import showTree
showTree(parseTree).mainloop()
else:
pprint.pprint(parseTree)
def _seq2st (seqobj):
"""_seq2st()
This recursively translates the more svelte sequence syntax tree to the
much more wasteful syntax tree representation returned by the parser
machinery.
This returns a pair consisting of a pair where the first item is the
translated tree and the second item is the line number for the tree (this
is used in an attempt to recursively reconstruct line number information
for nonterminal symbols).
"""
symbol_no = seqobj[0]
if symbol_no >= token.NT_OFFSET:
assert len(seqobj) > 1
# This is going to create a list of pairs of (node, line_no) data:
child_data = [_seq2st(child) for child in seqobj[1:]]
children = map(lambda (x,y) : x, child_data)
# Validate the children against the DFA for the non-terminal.
dfa = DFAParser.findDFA(pygrammar, symbol_no)
_validateChildren(dfa, children)
# Compute a line number and create the actual node object.
line_no = min(map(lambda (x, y) : y, child_data))
node = ((symbol_no, '', line_no), children)
else:
if len(seqobj) == 3:
node = (seqobj, [])
line_no = seqobj[2]
elif len(seqobj) == 2:
node = ((symbol_no, seqobj[1], 0), [])
line_no = 0
else:
raise ParserError("terminal nodes must have 2 or 3 entries")
return node, line_no
def _doParse (source, start):
"""_doParse()
Ignore the function behind the curtain! Even if it is kinda like the
CPython PyParser_SimpleParseString() (I think.)
"""
global pygrammar
tokenizer = PyTokenizer.PyTokenizer().tokenizeString(source)
return STType(DFAParser.parsetok(tokenizer, pygrammar, start))
def _validateChildren (dfa, children):
"""_validateChildren()
"""
global pygrammar
classify = lambda sym, name : DFAParser.classify(pygrammar, sym, name)
symbol_no, symbol_name, initial, states, first = dfa
crnt_state = states[initial]
for child in children:
((child_symbol, child_text, child_line_no), grandchildren) = child
ilabel = classify(child_symbol, child_text)
arcs, accel, accept = crnt_state
next_state = None
for (arc_label, arc_state) in arcs:
if ilabel == arc_label:
next_state = states[arc_state]
break
if next_state == None:
raise ParserError("symbol %d should be in %s" %
(ilabel, str(arcs)))
else:
crnt_state = next_state
if crnt_state[2] != 1:
raise ParserError("incomplete sequence of children (ended with %s)" %
str(child[0]))
as if st2tuple() was already called on the output. It's only claim to fame
is that is done using Pure Python(tm) with none of those icky C extensions
making it run fast.
"""
# ______________________________________________________________________
# Module imports
import token, exceptions, compiler
import PyTokenizer, PyGrammar, DFAParser
# ______________________________________________________________________
# XXX What I really want to do is parameterize this module over an
# input grammar object. Perhaps this can be done using an external
# class and then pyparser just calls into an instance of this class.
pygrammar = DFAParser.addAccelerators(PyGrammar.grammarObj)
# ______________________________________________________________________
# ParserError exception
class ParserError (exceptions.Exception):
"""Class ParserError
Exception class for parser errors (I assume).
"""
pass
# ______________________________________________________________________
class STType (object):
"""Class STType
"""
