initial year-end cleanup.

2 files changed, 1101 insertions, 0 deletions

diff --git a/example/cpp/cpp.py b/example/cpp/cpp.py
new file mode 100644
index 0000000..50a44a1
--- /dev/null
+++ b/example/cpp/cpp.py
@@ -0,0 +1,974 @@
+# -----------------------------------------------------------------------------
+# ply: cpp.py
+#
+# Copyright (C) 2001-2019
+# David M. Beazley (Dabeaz LLC)
+# All rights reserved.
+#
+# Latest version: https://github.com/dabeaz/ply
+#
+# Redistribution and use in source and binary forms, with or without
+# modification, are permitted provided that the following conditions are
+# met:
+#
+# * Redistributions of source code must retain the above copyright notice,
+#   this list of conditions and the following disclaimer.
+# * Redistributions in binary form must reproduce the above copyright notice,
+#   this list of conditions and the following disclaimer in the documentation
+#   and/or other materials provided with the distribution.
+# * Neither the name of David Beazley or Dabeaz LLC may be used to
+#   endorse or promote products derived from this software without
+#   specific prior written permission.
+#
+# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+# "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+# LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+# A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+# OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+# SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+# LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+# DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+# THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+# (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+# OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+# -----------------------------------------------------------------------------
+
+# This module implements an ANSI-C style lexical preprocessor for PLY.
+# -----------------------------------------------------------------------------
+from __future__ import generators
+
+import sys
+
+# Some Python 3 compatibility shims
+if sys.version_info.major < 3:
+    STRING_TYPES = (str, unicode)
+else:
+    STRING_TYPES = str
+    xrange = range
+
+# -----------------------------------------------------------------------------
+# Default preprocessor lexer definitions.   These tokens are enough to get
+# a basic preprocessor working.   Other modules may import these if they want
+# -----------------------------------------------------------------------------
+
+tokens = (
+   'CPP_ID','CPP_INTEGER', 'CPP_FLOAT', 'CPP_STRING', 'CPP_CHAR', 'CPP_WS', 'CPP_COMMENT1', 'CPP_COMMENT2', 'CPP_POUND','CPP_DPOUND'
+)
+
+literals = "+-*/%|&~^<>=!?()[]{}.,;:\\\'\""
+
+# Whitespace
+def t_CPP_WS(t):
+    r'\s+'
+    t.lexer.lineno += t.value.count("\n")
+    return t
+
+t_CPP_POUND = r'\#'
+t_CPP_DPOUND = r'\#\#'
+
+# Identifier
+t_CPP_ID = r'[A-Za-z_][\w_]*'
+
+# Integer literal
+def CPP_INTEGER(t):
+    r'(((((0x)|(0X))[0-9a-fA-F]+)|(\d+))([uU][lL]|[lL][uU]|[uU]|[lL])?)'
+    return t
+
+t_CPP_INTEGER = CPP_INTEGER
+
+# Floating literal
+t_CPP_FLOAT = r'((\d+)(\.\d+)(e(\+|-)?(\d+))? | (\d+)e(\+|-)?(\d+))([lL]|[fF])?'
+
+# String literal
+def t_CPP_STRING(t):
+    r'\"([^\\\n]|(\\(.|\n)))*?\"'
+    t.lexer.lineno += t.value.count("\n")
+    return t
+
+# Character constant 'c' or L'c'
+def t_CPP_CHAR(t):
+    r'(L)?\'([^\\\n]|(\\(.|\n)))*?\''
+    t.lexer.lineno += t.value.count("\n")
+    return t
+
+# Comment
+def t_CPP_COMMENT1(t):
+    r'(/\*(.|\n)*?\*/)'
+    ncr = t.value.count("\n")
+    t.lexer.lineno += ncr
+    # replace with one space or a number of '\n'
+    t.type = 'CPP_WS'; t.value = '\n' * ncr if ncr else ' '
+    return t
+
+# Line comment
+def t_CPP_COMMENT2(t):
+    r'(//.*?(\n|$))'
+    # replace with '/n'
+    t.type = 'CPP_WS'; t.value = '\n'
+    return t
+
+def t_error(t):
+    t.type = t.value[0]
+    t.value = t.value[0]
+    t.lexer.skip(1)
+    return t
+
+import re
+import copy
+import time
+import os.path
+
+# -----------------------------------------------------------------------------
+# trigraph()
+#
+# Given an input string, this function replaces all trigraph sequences.
+# The following mapping is used:
+#
+#     ??=    #
+#     ??/    \
+#     ??'    ^
+#     ??(    [
+#     ??)    ]
+#     ??!    |
+#     ??<    {
+#     ??>    }
+#     ??-    ~
+# -----------------------------------------------------------------------------
+
+_trigraph_pat = re.compile(r'''\?\?[=/\'\(\)\!<>\-]''')
+_trigraph_rep = {
+    '=':'#',
+    '/':'\\',
+    "'":'^',
+    '(':'[',
+    ')':']',
+    '!':'|',
+    '<':'{',
+    '>':'}',
+    '-':'~'
+}
+
+def trigraph(input):
+    return _trigraph_pat.sub(lambda g: _trigraph_rep[g.group()[-1]],input)
+
+# ------------------------------------------------------------------
+# Macro object
+#
+# This object holds information about preprocessor macros
+#
+#    .name      - Macro name (string)
+#    .value     - Macro value (a list of tokens)
+#    .arglist   - List of argument names
+#    .variadic  - Boolean indicating whether or not variadic macro
+#    .vararg    - Name of the variadic parameter
+#
+# When a macro is created, the macro replacement token sequence is
+# pre-scanned and used to create patch lists that are later used
+# during macro expansion
+# ------------------------------------------------------------------
+
+class Macro(object):
+    def __init__(self,name,value,arglist=None,variadic=False):
+        self.name = name
+        self.value = value
+        self.arglist = arglist
+        self.variadic = variadic
+        if variadic:
+            self.vararg = arglist[-1]
+        self.source = None
+
+# ------------------------------------------------------------------
+# Preprocessor object
+#
+# Object representing a preprocessor.  Contains macro definitions,
+# include directories, and other information
+# ------------------------------------------------------------------
+
+class Preprocessor(object):
+    def __init__(self,lexer=None):
+        if lexer is None:
+            lexer = lex.lexer
+        self.lexer = lexer
+        self.macros = { }
+        self.path = []
+        self.temp_path = []
+
+        # Probe the lexer for selected tokens
+        self.lexprobe()
+
+        tm = time.localtime()
+        self.define("__DATE__ \"%s\"" % time.strftime("%b %d %Y",tm))
+        self.define("__TIME__ \"%s\"" % time.strftime("%H:%M:%S",tm))
+        self.parser = None
+
+    # -----------------------------------------------------------------------------
+    # tokenize()
+    #
+    # Utility function. Given a string of text, tokenize into a list of tokens
+    # -----------------------------------------------------------------------------
+
+    def tokenize(self,text):
+        tokens = []
+        self.lexer.input(text)
+        while True:
+            tok = self.lexer.token()
+            if not tok: break
+            tokens.append(tok)
+        return tokens
+
+    # ---------------------------------------------------------------------
+    # error()
+    #
+    # Report a preprocessor error/warning of some kind
+    # ----------------------------------------------------------------------
+
+    def error(self,file,line,msg):
+        print("%s:%d %s" % (file,line,msg))
+
+    # ----------------------------------------------------------------------
+    # lexprobe()
+    #
+    # This method probes the preprocessor lexer object to discover
+    # the token types of symbols that are important to the preprocessor.
+    # If this works right, the preprocessor will simply "work"
+    # with any suitable lexer regardless of how tokens have been named.
+    # ----------------------------------------------------------------------
+
+    def lexprobe(self):
+
+        # Determine the token type for identifiers
+        self.lexer.input("identifier")
+        tok = self.lexer.token()
+        if not tok or tok.value != "identifier":
+            print("Couldn't determine identifier type")
+        else:
+            self.t_ID = tok.type
+
+        # Determine the token type for integers
+        self.lexer.input("12345")
+        tok = self.lexer.token()
+        if not tok or int(tok.value) != 12345:
+            print("Couldn't determine integer type")
+        else:
+            self.t_INTEGER = tok.type
+            self.t_INTEGER_TYPE = type(tok.value)
+
+        # Determine the token type for strings enclosed in double quotes
+        self.lexer.input("\"filename\"")
+        tok = self.lexer.token()
+        if not tok or tok.value != "\"filename\"":
+            print("Couldn't determine string type")
+        else:
+            self.t_STRING = tok.type
+
+        # Determine the token type for whitespace--if any
+        self.lexer.input("  ")
+        tok = self.lexer.token()
+        if not tok or tok.value != "  ":
+            self.t_SPACE = None
+        else:
+            self.t_SPACE = tok.type
+
+        # Determine the token type for newlines
+        self.lexer.input("\n")
+        tok = self.lexer.token()
+        if not tok or tok.value != "\n":
+            self.t_NEWLINE = None
+            print("Couldn't determine token for newlines")
+        else:
+            self.t_NEWLINE = tok.type
+
+        self.t_WS = (self.t_SPACE, self.t_NEWLINE)
+
+        # Check for other characters used by the preprocessor
+        chars = [ '<','>','#','##','\\','(',')',',','.']
+        for c in chars:
+            self.lexer.input(c)
+            tok = self.lexer.token()
+            if not tok or tok.value != c:
+                print("Unable to lex '%s' required for preprocessor" % c)
+
+    # ----------------------------------------------------------------------
+    # add_path()
+    #
+    # Adds a search path to the preprocessor.
+    # ----------------------------------------------------------------------
+
+    def add_path(self,path):
+        self.path.append(path)
+
+    # ----------------------------------------------------------------------
+    # group_lines()
+    #
+    # Given an input string, this function splits it into lines.  Trailing whitespace
+    # is removed.   Any line ending with \ is grouped with the next line.  This
+    # function forms the lowest level of the preprocessor---grouping into text into
+    # a line-by-line format.
+    # ----------------------------------------------------------------------
+
+    def group_lines(self,input):
+        lex = self.lexer.clone()
+        lines = [x.rstrip() for x in input.splitlines()]
+        for i in xrange(len(lines)):
+            j = i+1
+            while lines[i].endswith('\\') and (j < len(lines)):
+                lines[i] = lines[i][:-1]+lines[j]
+                lines[j] = ""
+                j += 1
+
+        input = "\n".join(lines)
+        lex.input(input)
+        lex.lineno = 1
+
+        current_line = []
+        while True:
+            tok = lex.token()
+            if not tok:
+                break
+            current_line.append(tok)
+            if tok.type in self.t_WS and '\n' in tok.value:
+                yield current_line
+                current_line = []
+
+        if current_line:
+            yield current_line
+
+    # ----------------------------------------------------------------------
+    # tokenstrip()
+    #
+    # Remove leading/trailing whitespace tokens from a token list
+    # ----------------------------------------------------------------------
+
+    def tokenstrip(self,tokens):
+        i = 0
+        while i < len(tokens) and tokens[i].type in self.t_WS:
+            i += 1
+        del tokens[:i]
+        i = len(tokens)-1
+        while i >= 0 and tokens[i].type in self.t_WS:
+            i -= 1
+        del tokens[i+1:]
+        return tokens
+
+
+    # ----------------------------------------------------------------------
+    # collect_args()
+    #
+    # Collects comma separated arguments from a list of tokens.   The arguments
+    # must be enclosed in parenthesis.  Returns a tuple (tokencount,args,positions)
+    # where tokencount is the number of tokens consumed, args is a list of arguments,
+    # and positions is a list of integers containing the starting index of each
+    # argument.  Each argument is represented by a list of tokens.
+    #
+    # When collecting arguments, leading and trailing whitespace is removed
+    # from each argument.
+    #
+    # This function properly handles nested parenthesis and commas---these do not
+    # define new arguments.
+    # ----------------------------------------------------------------------
+
+    def collect_args(self,tokenlist):
+        args = []
+        positions = []
+        current_arg = []
+        nesting = 1
+        tokenlen = len(tokenlist)
+
+        # Search for the opening '('.
+        i = 0
+        while (i < tokenlen) and (tokenlist[i].type in self.t_WS):
+            i += 1
+
+        if (i < tokenlen) and (tokenlist[i].value == '('):
+            positions.append(i+1)
+        else:
+            self.error(self.source,tokenlist[0].lineno,"Missing '(' in macro arguments")
+            return 0, [], []
+
+        i += 1
+
+        while i < tokenlen:
+            t = tokenlist[i]
+            if t.value == '(':
+                current_arg.append(t)
+                nesting += 1
+            elif t.value == ')':
+                nesting -= 1
+                if nesting == 0:
+                    if current_arg:
+                        args.append(self.tokenstrip(current_arg))
+                        positions.append(i)
+                    return i+1,args,positions
+                current_arg.append(t)
+            elif t.value == ',' and nesting == 1:
+                args.append(self.tokenstrip(current_arg))
+                positions.append(i+1)
+                current_arg = []
+            else:
+                current_arg.append(t)
+            i += 1
+
+        # Missing end argument
+        self.error(self.source,tokenlist[-1].lineno,"Missing ')' in macro arguments")
+        return 0, [],[]
+
+    # ----------------------------------------------------------------------
+    # macro_prescan()
+    #
+    # Examine the macro value (token sequence) and identify patch points
+    # This is used to speed up macro expansion later on---we'll know
+    # right away where to apply patches to the value to form the expansion
+    # ----------------------------------------------------------------------
+
+    def macro_prescan(self,macro):
+        macro.patch     = []             # Standard macro arguments
+        macro.str_patch = []             # String conversion expansion
+        macro.var_comma_patch = []       # Variadic macro comma patch
+        i = 0
+        while i < len(macro.value):
+            if macro.value[i].type == self.t_ID and macro.value[i].value in macro.arglist:
+                argnum = macro.arglist.index(macro.value[i].value)
+                # Conversion of argument to a string
+                if i > 0 and macro.value[i-1].value == '#':
+                    macro.value[i] = copy.copy(macro.value[i])
+                    macro.value[i].type = self.t_STRING
+                    del macro.value[i-1]
+                    macro.str_patch.append((argnum,i-1))
+                    continue
+                # Concatenation
+                elif (i > 0 and macro.value[i-1].value == '##'):
+                    macro.patch.append(('c',argnum,i-1))
+                    del macro.value[i-1]
+                    i -= 1
+                    continue
+                elif ((i+1) < len(macro.value) and macro.value[i+1].value == '##'):
+                    macro.patch.append(('c',argnum,i))
+                    del macro.value[i + 1]
+                    continue
+                # Standard expansion
+                else:
+                    macro.patch.append(('e',argnum,i))
+            elif macro.value[i].value == '##':
+                if macro.variadic and (i > 0) and (macro.value[i-1].value == ',') and \
+                        ((i+1) < len(macro.value)) and (macro.value[i+1].type == self.t_ID) and \
+                        (macro.value[i+1].value == macro.vararg):
+                    macro.var_comma_patch.append(i-1)
+            i += 1
+        macro.patch.sort(key=lambda x: x[2],reverse=True)
+
+    # ----------------------------------------------------------------------
+    # macro_expand_args()
+    #
+    # Given a Macro and list of arguments (each a token list), this method
+    # returns an expanded version of a macro.  The return value is a token sequence
+    # representing the replacement macro tokens
+    # ----------------------------------------------------------------------
+
+    def macro_expand_args(self,macro,args,expanded):
+        # Make a copy of the macro token sequence
+        rep = [copy.copy(_x) for _x in macro.value]
+
+        # Make string expansion patches.  These do not alter the length of the replacement sequence
+
+        str_expansion = {}
+        for argnum, i in macro.str_patch:
+            if argnum not in str_expansion:
+                str_expansion[argnum] = ('"%s"' % "".join([x.value for x in args[argnum]])).replace("\\","\\\\")
+            rep[i] = copy.copy(rep[i])
+            rep[i].value = str_expansion[argnum]
+
+        # Make the variadic macro comma patch.  If the variadic macro argument is empty, we get rid
+        comma_patch = False
+        if macro.variadic and not args[-1]:
+            for i in macro.var_comma_patch:
+                rep[i] = None
+                comma_patch = True
+
+        # Make all other patches.   The order of these matters.  It is assumed that the patch list
+        # has been sorted in reverse order of patch location since replacements will cause the
+        # size of the replacement sequence to expand from the patch point.
+
+        expanded_args = { }
+        for ptype, argnum, i in macro.patch:
+            # Concatenation.   Argument is left unexpanded
+            if ptype == 'c':
+                rep[i:i+1] = args[argnum]
+            # Normal expansion.  Argument is macro expanded first
+            elif ptype == 'e':
+                if argnum not in expanded_args:
+                    expanded_args[argnum] = self.expand_macros(args[argnum],expanded)
+                rep[i:i+1] = expanded_args[argnum]
+
+        # Get rid of removed comma if necessary
+        if comma_patch:
+            rep = [_i for _i in rep if _i]
+
+        return rep
+
+
+    # ----------------------------------------------------------------------
+    # expand_macros()
+    #
+    # Given a list of tokens, this function performs macro expansion.
+    # The expanded argument is a dictionary that contains macros already
+    # expanded.  This is used to prevent infinite recursion.
+    # ----------------------------------------------------------------------
+
+    def expand_macros(self,tokens,expanded=None):
+        if expanded is None:
+            expanded = {}
+        i = 0
+        while i < len(tokens):
+            t = tokens[i]
+            if t.type == self.t_ID:
+                if t.value in self.macros and t.value not in expanded:
+                    # Yes, we found a macro match
+                    expanded[t.value] = True
+
+                    m = self.macros[t.value]
+                    if not m.arglist:
+                        # A simple macro
+                        ex = self.expand_macros([copy.copy(_x) for _x in m.value],expanded)
+                        for e in ex:
+                            e.lineno = t.lineno
+                        tokens[i:i+1] = ex
+                        i += len(ex)
+                    else:
+                        # A macro with arguments
+                        j = i + 1
+                        while j < len(tokens) and tokens[j].type in self.t_WS:
+                            j += 1
+                        if j < len(tokens) and tokens[j].value == '(':
+                            tokcount,args,positions = self.collect_args(tokens[j:])
+                            if not m.variadic and len(args) !=  len(m.arglist):
+                                self.error(self.source,t.lineno,"Macro %s requires %d arguments" % (t.value,len(m.arglist)))
+                                i = j + tokcount
+                            elif m.variadic and len(args) < len(m.arglist)-1:
+                                if len(m.arglist) > 2:
+                                    self.error(self.source,t.lineno,"Macro %s must have at least %d arguments" % (t.value, len(m.arglist)-1))
+                                else:
+                                    self.error(self.source,t.lineno,"Macro %s must have at least %d argument" % (t.value, len(m.arglist)-1))
+                                i = j + tokcount
+                            else:
+                                if m.variadic:
+                                    if len(args) == len(m.arglist)-1:
+                                        args.append([])
+                                    else:
+                                        args[len(m.arglist)-1] = tokens[j+positions[len(m.arglist)-1]:j+tokcount-1]
+                                        del args[len(m.arglist):]
+
+                                # Get macro replacement text
+                                rep = self.macro_expand_args(m,args,expanded)
+                                rep = self.expand_macros(rep,expanded)
+                                for r in rep:
+                                    r.lineno = t.lineno
+                                tokens[i:j+tokcount] = rep
+                                i += len(rep)
+                        else:
+                            # This is not a macro. It is just a word which
+                            # equals to name of the macro. Hence, go to the
+                            # next token.
+                            i += 1
+
+                    del expanded[t.value]
+                    continue
+                elif t.value == '__LINE__':
+                    t.type = self.t_INTEGER
+                    t.value = self.t_INTEGER_TYPE(t.lineno)
+
+            i += 1
+        return tokens
+
+    # ----------------------------------------------------------------------
+    # evalexpr()
+    #
+    # Evaluate an expression token sequence for the purposes of evaluating
+    # integral expressions.
+    # ----------------------------------------------------------------------
+
+    def evalexpr(self,tokens):
+        # tokens = tokenize(line)
+        # Search for defined macros
+        i = 0
+        while i < len(tokens):
+            if tokens[i].type == self.t_ID and tokens[i].value == 'defined':
+                j = i + 1
+                needparen = False
+                result = "0L"
+                while j < len(tokens):
+                    if tokens[j].type in self.t_WS:
+                        j += 1
+                        continue
+                    elif tokens[j].type == self.t_ID:
+                        if tokens[j].value in self.macros:
+                            result = "1L"
+                        else:
+                            result = "0L"
+                        if not needparen: break
+                    elif tokens[j].value == '(':
+                        needparen = True
+                    elif tokens[j].value == ')':
+                        break
+                    else:
+                        self.error(self.source,tokens[i].lineno,"Malformed defined()")
+                    j += 1
+                tokens[i].type = self.t_INTEGER
+                tokens[i].value = self.t_INTEGER_TYPE(result)
+                del tokens[i+1:j+1]
+            i += 1
+        tokens = self.expand_macros(tokens)
+        return self.evalexpr_expanded(tokens)
+
+    # ----------------------------------------------------------------------
+    # evalexpr_expanded()
+    #
+    # Helper for evalexpr that evaluates the expression that had its macros
+    # and defined(...) expressions expanded by evalexpr
+    # ----------------------------------------------------------------------
+
+    def evalexpr_expanded(self, tokens):
+        for i,t in enumerate(tokens):
+            if t.type == self.t_ID:
+                tokens[i] = copy.copy(t)
+                tokens[i].type = self.t_INTEGER
+                tokens[i].value = self.t_INTEGER_TYPE("0")
+            elif t.type == self.t_INTEGER:
+                tokens[i] = copy.copy(t)
+                # Strip off any trailing suffixes
+                tokens[i].value = str(tokens[i].value)
+                while tokens[i].value[-1] not in "0123456789abcdefABCDEF":
+                    tokens[i].value = tokens[i].value[:-1]
+
+        return self.evalexpr_string("".join([str(x.value) for x in tokens]))
+
+    # ----------------------------------------------------------------------
+    # evalexpr_string()
+    #
+    # Helper for evalexpr that evaluates a string expression
+    # This implementation does basic C->python conversion and then uses eval()
+    # ----------------------------------------------------------------------
+    def evalexpr_string(self, expr):
+        expr = expr.replace("&&"," and ")
+        expr = expr.replace("||"," or ")
+        expr = expr.replace("!"," not ")
+        expr = expr.replace(" not ="," !=")
+        try:
+            result = eval(expr)
+        except Exception:
+            self.error(self.source,tokens[0].lineno,"Couldn't evaluate expression")
+            result = 0
+        return result
+
+    # ----------------------------------------------------------------------
+    # parsegen()
+    #
+    # Parse an input string/
+    # ----------------------------------------------------------------------
+    def parsegen(self,input,source=None):
+
+        # Replace trigraph sequences
+        t = trigraph(input)
+        lines = self.group_lines(t)
+
+        if not source:
+            source = ""
+
+        self.define("__FILE__ \"%s\"" % source)
+
+        self.source = source
+        chunk = []
+        enable = True
+        iftrigger = False
+        ifstack = []
+
+        for x in lines:
+            for i,tok in enumerate(x):
+                if tok.type not in self.t_WS: break
+            if tok.value == '#':
+                # Preprocessor directive
+
+                # insert necessary whitespace instead of eaten tokens
+                for tok in x:
+                    if tok.type in self.t_WS and '\n' in tok.value:
+                        chunk.append(tok)
+
+                dirtokens = self.tokenstrip(x[i+1:])
+                if dirtokens:
+                    name = dirtokens[0].value
+                    args = self.tokenstrip(dirtokens[1:])
+                else:
+                    name = ""
+                    args = []
+
+                if name == 'define':
+                    if enable:
+                        for tok in self.expand_macros(chunk):
+                            yield tok
+                        chunk = []
+                        self.define(args)
+                elif name == 'include':
+                    if enable:
+                        for tok in self.expand_macros(chunk):
+                            yield tok
+                        chunk = []
+                        oldfile = self.macros['__FILE__']
+                        for tok in self.include(args):
+                            yield tok
+                        self.macros['__FILE__'] = oldfile
+                        self.source = source
+                elif name == 'undef':
+                    if enable:
+                        for tok in self.expand_macros(chunk):
+                            yield tok
+                        chunk = []
+                        self.undef(args)
+                elif name == 'ifdef':
+                    ifstack.append((enable,iftrigger))
+                    if enable:
+                        if not args[0].value in self.macros:
+                            enable = False
+                            iftrigger = False
+                        else:
+                            iftrigger = True
+                elif name == 'ifndef':
+                    ifstack.append((enable,iftrigger))
+                    if enable:
+                        if args[0].value in self.macros:
+                            enable = False
+                            iftrigger = False
+                        else:
+                            iftrigger = True
+                elif name == 'if':
+                    ifstack.append((enable,iftrigger))
+                    if enable:
+                        result = self.evalexpr(args)
+                        if not result:
+                            enable = False
+                            iftrigger = False
+                        else:
+                            iftrigger = True
+                elif name == 'elif':
+                    if ifstack:
+                        if ifstack[-1][0]:     # We only pay attention if outer "if" allows this
+                            if enable:         # If already true, we flip enable False
+                                enable = False
+                            elif not iftrigger:   # If False, but not triggered yet, we'll check expression
+                                result = self.evalexpr(args)
+                                if result:
+                                    enable  = True
+                                    iftrigger = True
+                    else:
+                        self.error(self.source,dirtokens[0].lineno,"Misplaced #elif")
+
+                elif name == 'else':
+                    if ifstack:
+                        if ifstack[-1][0]:
+                            if enable:
+                                enable = False
+                            elif not iftrigger:
+                                enable = True
+                                iftrigger = True
+                    else:
+                        self.error(self.source,dirtokens[0].lineno,"Misplaced #else")
+
+                elif name == 'endif':
+                    if ifstack:
+                        enable,iftrigger = ifstack.pop()
+                    else:
+                        self.error(self.source,dirtokens[0].lineno,"Misplaced #endif")
+                else:
+                    # Unknown preprocessor directive
+                    pass
+
+            else:
+                # Normal text
+                if enable:
+                    chunk.extend(x)
+
+        for tok in self.expand_macros(chunk):
+            yield tok
+        chunk = []
+
+    # ----------------------------------------------------------------------
+    # include()
+    #
+    # Implementation of file-inclusion
+    # ----------------------------------------------------------------------
+
+    def include(self,tokens):
+        # Try to extract the filename and then process an include file
+        if not tokens:
+            return
+        if tokens:
+            if tokens[0].value != '<' and tokens[0].type != self.t_STRING:
+                tokens = self.expand_macros(tokens)
+
+            if tokens[0].value == '<':
+                # Include <...>
+                i = 1
+                while i < len(tokens):
+                    if tokens[i].value == '>':
+                        break
+                    i += 1
+                else:
+                    print("Malformed #include <...>")
+                    return
+                filename = "".join([x.value for x in tokens[1:i]])
+                path = self.path + [""] + self.temp_path
+            elif tokens[0].type == self.t_STRING:
+                filename = tokens[0].value[1:-1]
+                path = self.temp_path + [""] + self.path
+            else:
+                print("Malformed #include statement")
+                return
+        for p in path:
+            iname = os.path.join(p,filename)
+            try:
+                data = self.read_include_file(iname)
+                dname = os.path.dirname(iname)
+                if dname:
+                    self.temp_path.insert(0,dname)
+                for tok in self.parsegen(data,filename):
+                    yield tok
+                if dname:
+                    del self.temp_path[0]
+                break
+            except IOError:
+                pass
+        else:
+            print("Couldn't find '%s'" % filename)
+
+    # ----------------------------------------------------------------------
+    # read_include_file()
+    #
+    # Reads a source file for inclusion using #include
+    # Could be overridden to e.g. customize encoding, limit access to
+    # certain paths on the filesystem, or provide the contents of system
+    # include files
+    # ----------------------------------------------------------------------
+
+    def read_include_file(self, filepath):
+        with open(filepath, 'r', encoding='utf-8', errors='surrogateescape') as file:
+            return file.read()
+
+    # ----------------------------------------------------------------------
+    # define()
+    #
+    # Define a new macro
+    # ----------------------------------------------------------------------
+
+    def define(self,tokens):
+        if isinstance(tokens,STRING_TYPES):
+            tokens = self.tokenize(tokens)
+
+        linetok = tokens
+        try:
+            name = linetok[0]
+            if len(linetok) > 1:
+                mtype = linetok[1]
+            else:
+                mtype = None
+            if not mtype:
+                m = Macro(name.value,[])
+                self.macros[name.value] = m
+            elif mtype.type in self.t_WS:
+                # A normal macro
+                m = Macro(name.value,self.tokenstrip(linetok[2:]))
+                self.macros[name.value] = m
+            elif mtype.value == '(':
+                # A macro with arguments
+                tokcount, args, positions = self.collect_args(linetok[1:])
+                variadic = False
+                for a in args:
+                    if variadic:
+                        print("No more arguments may follow a variadic argument")
+                        break
+                    astr = "".join([str(_i.value) for _i in a])
+                    if astr == "...":
+                        variadic = True
+                        a[0].type = self.t_ID
+                        a[0].value = '__VA_ARGS__'
+                        variadic = True
+                        del a[1:]
+                        continue
+                    elif astr[-3:] == "..." and a[0].type == self.t_ID:
+                        variadic = True
+                        del a[1:]
+                        # If, for some reason, "." is part of the identifier, strip off the name for the purposes
+                        # of macro expansion
+                        if a[0].value[-3:] == '...':
+                            a[0].value = a[0].value[:-3]
+                        continue
+                    if len(a) > 1 or a[0].type != self.t_ID:
+                        print("Invalid macro argument")
+                        break
+                else:
+                    mvalue = self.tokenstrip(linetok[1+tokcount:])
+                    i = 0
+                    while i < len(mvalue):
+                        if i+1 < len(mvalue):
+                            if mvalue[i].type in self.t_WS and mvalue[i+1].value == '##':
+                                del mvalue[i]
+                                continue
+                            elif mvalue[i].value == '##' and mvalue[i+1].type in self.t_WS:
+                                del mvalue[i+1]
+                        i += 1
+                    m = Macro(name.value,mvalue,[x[0].value for x in args],variadic)
+                    self.macro_prescan(m)
+                    self.macros[name.value] = m
+            else:
+                print("Bad macro definition")
+        except LookupError:
+            print("Bad macro definition")
+
+    # ----------------------------------------------------------------------
+    # undef()
+    #
+    # Undefine a macro
+    # ----------------------------------------------------------------------
+
+    def undef(self,tokens):
+        id = tokens[0].value
+        try:
+            del self.macros[id]
+        except LookupError:
+            pass
+
+    # ----------------------------------------------------------------------
+    # parse()
+    #
+    # Parse input text.
+    # ----------------------------------------------------------------------
+    def parse(self,input,source=None,ignore={}):
+        self.ignore = ignore
+        self.parser = self.parsegen(input,source)
+
+    # ----------------------------------------------------------------------
+    # token()
+    #
+    # Method to return individual tokens
+    # ----------------------------------------------------------------------
+    def token(self):
+        try:
+            while True:
+                tok = next(self.parser)
+                if tok.type not in self.ignore: return tok
+        except StopIteration:
+            self.parser = None
+            return None
+
+if __name__ == '__main__':
+    import ply.lex as lex
+    lexer = lex.lex()
+
+    # Run a preprocessor
+    import sys
+    with open(sys.argv[1]) as f:
+        input = f.read()
+
+    p = Preprocessor(lexer)
+    p.parse(input,sys.argv[1])
+    while True:
+        tok = p.token()
+        if not tok: break
+        print(p.source, tok)
diff --git a/example/ctokens/ctokens.py b/example/ctokens/ctokens.py
new file mode 100644
index 0000000..b265e59
--- /dev/null
+++ b/example/ctokens/ctokens.py
@@ -0,0 +1,127 @@
+# ----------------------------------------------------------------------
+# ctokens.py
+#
+# Token specifications for symbols in ANSI C and C++.  This file is
+# meant to be used as a library in other tokenizers.
+# ----------------------------------------------------------------------
+
+# Reserved words
+
+tokens = [
+    # Literals (identifier, integer constant, float constant, string constant, char const)
+    'ID', 'TYPEID', 'INTEGER', 'FLOAT', 'STRING', 'CHARACTER',
+
+    # Operators (+,-,*,/,%,|,&,~,^,<<,>>, ||, &&, !, <, <=, >, >=, ==, !=)
+    'PLUS', 'MINUS', 'TIMES', 'DIVIDE', 'MODULO',
+    'OR', 'AND', 'NOT', 'XOR', 'LSHIFT', 'RSHIFT',
+    'LOR', 'LAND', 'LNOT',
+    'LT', 'LE', 'GT', 'GE', 'EQ', 'NE',
+
+    # Assignment (=, *=, /=, %=, +=, -=, <<=, >>=, &=, ^=, |=)
+    'EQUALS', 'TIMESEQUAL', 'DIVEQUAL', 'MODEQUAL', 'PLUSEQUAL', 'MINUSEQUAL',
+    'LSHIFTEQUAL','RSHIFTEQUAL', 'ANDEQUAL', 'XOREQUAL', 'OREQUAL',
+
+    # Increment/decrement (++,--)
+    'INCREMENT', 'DECREMENT',
+
+    # Structure dereference (->)
+    'ARROW',
+
+    # Ternary operator (?)
+    'TERNARY',
+
+    # Delimeters ( ) [ ] { } , . ; :
+    'LPAREN', 'RPAREN',
+    'LBRACKET', 'RBRACKET',
+    'LBRACE', 'RBRACE',
+    'COMMA', 'PERIOD', 'SEMI', 'COLON',
+
+    # Ellipsis (...)
+    'ELLIPSIS',
+]
+
+# Operators
+t_PLUS             = r'\+'
+t_MINUS            = r'-'
+t_TIMES            = r'\*'
+t_DIVIDE           = r'/'
+t_MODULO           = r'%'
+t_OR               = r'\|'
+t_AND              = r'&'
+t_NOT              = r'~'
+t_XOR              = r'\^'
+t_LSHIFT           = r'<<'
+t_RSHIFT           = r'>>'
+t_LOR              = r'\|\|'
+t_LAND             = r'&&'
+t_LNOT             = r'!'
+t_LT               = r'<'
+t_GT               = r'>'
+t_LE               = r'<='
+t_GE               = r'>='
+t_EQ               = r'=='
+t_NE               = r'!='
+
+# Assignment operators
+
+t_EQUALS           = r'='
+t_TIMESEQUAL       = r'\*='
+t_DIVEQUAL         = r'/='
+t_MODEQUAL         = r'%='
+t_PLUSEQUAL        = r'\+='
+t_MINUSEQUAL       = r'-='
+t_LSHIFTEQUAL      = r'<<='
+t_RSHIFTEQUAL      = r'>>='
+t_ANDEQUAL         = r'&='
+t_OREQUAL          = r'\|='
+t_XOREQUAL         = r'\^='
+
+# Increment/decrement
+t_INCREMENT        = r'\+\+'
+t_DECREMENT        = r'--'
+
+# ->
+t_ARROW            = r'->'
+
+# ?
+t_TERNARY          = r'\?'
+
+# Delimeters
+t_LPAREN           = r'\('
+t_RPAREN           = r'\)'
+t_LBRACKET         = r'\['
+t_RBRACKET         = r'\]'
+t_LBRACE           = r'\{'
+t_RBRACE           = r'\}'
+t_COMMA            = r','
+t_PERIOD           = r'\.'
+t_SEMI             = r';'
+t_COLON            = r':'
+t_ELLIPSIS         = r'\.\.\.'
+
+# Identifiers
+t_ID = r'[A-Za-z_][A-Za-z0-9_]*'
+
+# Integer literal
+t_INTEGER = r'\d+([uU]|[lL]|[uU][lL]|[lL][uU])?'
+
+# Floating literal
+t_FLOAT = r'((\d+)(\.\d+)(e(\+|-)?(\d+))? | (\d+)e(\+|-)?(\d+))([lL]|[fF])?'
+
+# String literal
+t_STRING = r'\"([^\\\n]|(\\.))*?\"'
+
+# Character constant 'c' or L'c'
+t_CHARACTER = r'(L)?\'([^\\\n]|(\\.))*?\''
+
+# Comment (C-Style)
+def t_COMMENT(t):
+    r'/\*(.|\n)*?\*/'
+    t.lexer.lineno += t.value.count('\n')
+    return t
+
+# Comment (C++-Style)
+def t_CPPCOMMENT(t):
+    r'//.*\n'
+    t.lexer.lineno += 1
+    return t