# ----------------------------------------------------------------------------- # cpp.py # # Author: David Beazley (http://www.dabeaz.com) # Copyright (C) 2017 # All rights reserved # # This module implements an ANSI-C style lexical preprocessor for PLY. # ----------------------------------------------------------------------------- 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] continue elif ((i+1) < len(macro.value) and macro.value[i+1].value == '##'): macro.patch.append(('c',argnum,i)) 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): # 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 = { } 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: expanded[argnum] = self.expand_macros(args[argnum]) rep[i:i+1] = expanded[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 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) rep = self.expand_macros(rep,expanded) for r in rep: r.lineno = t.lineno tokens[i:j+tokcount] = rep i += len(rep) 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) 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("0L") 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] expr = "".join([str(x.value) for x in tokens]) expr = expr.replace("&&"," and ") expr = expr.replace("||"," or ") 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 = open(iname,"r").read() 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) # ---------------------------------------------------------------------- # 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 f = open(sys.argv[1]) 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)