# ***** BEGIN LICENSE BLOCK *****
# Version: MPL 1.1/GPL 2.0/LGPL 2.1
#
# The contents of this file are subject to the Mozilla Public License Version
# 1.1 (the "License"); you may not use this file except in compliance with
# the License. You may obtain a copy of the License at
# http://www.mozilla.org/MPL/
#
# Software distributed under the License is distributed on an "AS IS" basis,
# WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License
# for the specific language governing rights and limitations under the
# License.
#
# The Original Code is the Python Computer Graphics Kit.
#
# The Initial Developer of the Original Code is Matthias Baas.
# Portions created by the Initial Developer are Copyright (C) 2004
# the Initial Developer. All Rights Reserved.
#
# Contributor(s):
#
# Alternatively, the contents of this file may be used under the terms of
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# ***** END LICENSE BLOCK *****
# $Id: simplecpp.py,v 1.2 2006/01/27 22:11:09 mbaas Exp $

import sys, types, os.path

class Context:
    """This class carries information about a particular source file.
    """
    def __init__(self, filehandle):
        # The file handle (file-like object)
        self.filehandle = filehandle
        # The current line number (i.e. the line number of the next read line)
        self.linenr = 1
        # The file name
        self.filename = getattr(filehandle, "name", "<?>")
        
        self.condition_list = []
        # Flag that specifies whether a line should be ignored or not
        self.output_line = True
        

# PreProcessor
class PreProcessor:
    """A simple 'preprocessor'.

    This class implements a subset of the functionality of the C preprocessor.
    """

    def __init__(self, defines=None, includedirs=None):
        """Constructor.
        
        defines is a list of tuples (name, value) that specify the initial set
        of defined macros.
        includedirs is a list of strings that is used to find include files.
        """

        # The error stream
        self.errstream = sys.stderr
        
        # Flag that specifies if the starting position of the next line is
        # already inside a comment (i.e. if there was a '/*' without a '*/'
        self.inside_comment = False
        
        # A 'stack' of Context objects
        self.context_stack = []
        # Current context (this is the topmost element from context_stack)
        self.context = None
        
        # Contains the defined macros.
        self.defined = {}
        # This is a sorted list containing the macros (longest names first)
        # The items are tuples (name, value).
        self.substitution_list = []
        
        self.output_buffer = []

        # Set the predefined macros
        if defines!=None:
            for name,val in defines:
                if val==None:
                    val = ""
                self.onDefine("define", "%s %s"%(name, str(val)))

        # Set the include directories
        self.includedirs = []
        if includedirs!=None:
            self.includedirs.extend(includedirs)

    def __call__(self, source, errstream=None):
        """Preprocess a file or a file-like object.

        source may either be the name of a file or a file-like object.
        """
        
        self.errstream = errstream
        
        if isinstance(source, types.StringTypes):
            fhandle = file(source, "rt")
        else:
            fhandle = source

        self.output_buffer = []
        self.preprocess(fhandle)
        return "\n".join(self.output_buffer)

    def preprocess(self, fhandle):
        """Preprocess a source file.
        """
        
        self.context_stack = []
        self.context = None
        ctx = Context(fhandle)
        self.readFile(ctx)
        
    def readFile(self, ctx):
        """Read another file.
        
        ctx is a initialized Context object.
        """
        
        self.pushContext(ctx)
        linebuffer = ""
        defined = self.defined
        
        for line in ctx.filehandle:
            if line[-1:]=='\n':
                line = line[:-1]
            # Append the line to the line buffer...
            if line[-1:]=='\\':
                linebuffer += line[:-1]
                # Read another line before processing the line
                self.context.linenr += 1
                continue
            else:
                linebuffer += line
                
            intervals = list(self.iterStringIntervals(linebuffer))
            out = "".join(intervals)
                 
            stripped = out.strip()
            # Preprocessor directive?
            if stripped[:1]=="#":
                s = stripped[1:].strip()
                a = s.split()
                directive = a[0].lower()
                handlername = "on%s"%directive.capitalize()
                arg = s[len(directive)+1:].strip()
                handler = getattr(self, handlername, None)
                if handler!=None:
                    handler(directive, arg)
            else:
                out = ""
                for s in intervals:
                    # Do substitutions if it's not a string
                    if s[0:]!='"':
                        for name,value in self.substitution_list:
                            s = s.replace(name, value)
                    out += s

                if ctx.output_line:
                    self.output(out)
                else:
                    self.output("")
            
            self.context.linenr += 1
            linebuffer = ""
            
        self.popContext()

    def output(self, s):
        """This method is called for every output line.
        """
        self.output_buffer.append(s)
            
    def onInclude(self, directive, arg):
        """Handle #include directives.
        """
        filename = arg[1:-1]
        fullfilename = self.findFile(filename)
        if fullfilename==None:
            ctx = self.context
            print >>self.errstream, "%s:%d: %s: No such file or directory"%(ctx.filename, ctx.linenr, filename)
            return

        f = file(fullfilename, "rt")
        ctx = Context(f)
        self.readFile(ctx)
        
    def onDefine(self, directive, arg):
        """Handle #define directives.
        """
        a = arg.split()
        if len(a)==0:
            ctx = self.context
            print >>self.errstream, "%s:%d: Invalid macro definition"%(ctx.filename, ctx.linenr)
            return
        name = a[0]
        value = " ".join(a[1:])
        self.defined[name] = value
        self.substitution_list.append((name, value))
        self.substitution_list.sort(cmp=lambda a,b: cmp(len(b[0]), len(a[0])))

    def onUndef(self, directive, arg):
        """Handle #undef directives.
        """
        if arg=="":
            ctx = self.context
            print >>self.errstream, "%s:%d: Invalid macro name"%(ctx.filename, ctx.linenr)
            return
        if arg not in self.defined:
            return
        
        del self.defined[arg]
        # Remove the macro from the substitution list
        lst = []
        for name,value in self.substitution_list:
            if name!=arg:
                lst.append((name,value))
        self.substitution_list = lst
        
    def onIf(self, directive, arg):
        """Handle #if directives.
        """
        try:
            cond = bool(int(arg))
        except:
            cond = False
        self.context.condition_list.append(cond)
        self.context.output_line = cond
        
    def onIfdef(self, directive, arg):
        """Handle #ifdef directives.
        """
        a = arg.split()
        if len(a)==0:
            ctx = self.context
            print >>self.errstream, "%s:%d: '#ifdef' with no argument"%(ctx.filename, ctx.linenr)
            return

        name = a[0]
        cond = self.defined.has_key(name)
        self.context.condition_list.append(cond)
        self.context.output_line = cond

    def onIfndef(self, directive, arg):
        """Handle #ifndef directives.
        """
        a = arg.split()
        if len(a)==0:
            ctx = self.context
            print >>self.errstream, "%s:%d: '#ifndef' with no argument"%(ctx.filename, ctx.linenr)
            return
        
        name = a[0]
        cond = not self.defined.has_key(name)
        self.context.condition_list.append(cond)
        self.context.output_line = cond

    def onElif(self, directive, arg):
        """Handle #elif directives.
        """
        try:
            cond = bool(int(arg))
        except:
            cond = False
        self.context.output_line = cond
        
    def onElse(self, directive, arg):
        """Handle #else directives.
        """
        self.context.output_line = not self.context.output_line
                
    def onEndif(self, directive, arg):
        """Handle #endif directives.
        """
        if len(self.context.condition_list)==0:
            print >>self.errstream, "%s:%d: unbalanced '#endif'"%(self.context.filename, self.context.linenr)
            return
        
        self.context.condition_list.pop()
        self.context.output_line = True
        
    def onPragma(self, directive, arg):
        """Handle #pragma directives.
        """
        pass

    def pushContext(self, ctx):
        """Push a context object onto the context stack.
        """
        self.context_stack.append(ctx)
        self.context = ctx
        self.output('# %d "%s"'%(ctx.linenr, ctx.filename))
        
    def popContext(self):
        """Pop the topmost context object from the context stack.
        """
        ctx = self.context_stack.pop()
        if len(self.context_stack)==0:
            self.context = None
        else:
            self.context = self.context_stack[-1]
            self.output('# %d "%s"'%(self.context.linenr, self.context.filename))
            self.output("")
        return ctx

    def findFile(self, filename):
        """Search for an include file and return its name.

        The returned file name is guaranteed to refer to an existing file.
        If the file is not found None is returned.
        """
        
        if os.path.exists(filename):
            return filename

        for incdir in self.includedirs:
            name = os.path.join(incdir, filename)
            if os.path.exists(name):
                return name

        return None
        

    def iterStringIntervals(self, s):
        """Iterate over the separate 'intervals' in the given string.
        
        This iterator splits the string into several intervals and yields
        each interval. The intervals can be one of the following:
        
        - Content: Anything outside a comment and outside a string
        - String: Always begins with '"'
        - Comment: Is replaced by blanks (or not yielded at all)
        
        Example string: 
        
          'result = myfunc(5, "text" /* comment */, 6) // Comment'
          
        Intervals:
        
        - 'result = myfunc(5, '
        - '"text"'
        - ' '
        - '             '
        - ', 6) '
        """

        slength = len(s)

        start = 0
        while start<slength:
        
            if self.inside_comment:
                # Search for the end of the comment
                n = s.find('*/', start)
                if n==-1:
                    start = slength
                else:
                    self.inside_comment = False
                    start = n+2
            else:
                n1 = s.find('//', start)
                n2 = s.find('/*', start)
                n3 = s.find('"', start)

                # Determine which of the above strings is encountered first...
                if n1==-1:
                    if n2==-1:
                        if n3==-1:
                            # n1==-1 and n2==-1 and n3==-1
                            first = 0
                        else:
                            # n1==-1 and n2==-1 and n3!=-1
                            first = 3
                    else:
                        if n3==-1:
                            # n1==-1 and n2!=-1 and n3==-1
                            first = 2
                        else:
                            # n1==-1 and n2!=-1 and n3!=-1
                            if n2<n3:
                                first = 2
                            else:
                                first = 3
                else:
                    if n2==-1:
                        if n3==-1:
                            # n1!=-1 and n2==-1 and n3==-1
                            first = 1
                        else:
                            # n1!=-1 and n2==-1 and n3!=-1
                            if n1<n3:
                                first = 1
                            else:
                                first = 3
                    else:
                        if n3==-1:
                            # n1!=-1 and n2!=-1 and n3==-1
                            if n1<n2:
                                first = 1
                            else:
                                first = 2
                        else:
                            # n1!=-1 and n2!=-1 and n3!=-1
                            if n1<n2 and n1<n3:
                                first = 1
                            else:
                                if n2<n3:
                                    first = 2
                                else:
                                    first = 3

                # Neither a comment, nor quotes
                if first==0:
                    # The entire remaining string is content
                    yield s[start:]
                    start = slength
                # '//' comment
                elif first==1:
                    if n1>start:
                        yield s[start:n1]
                    start = slength
                # '/*' comment
                elif first==2:
                    if n2>start:
                        yield s[start:n2]
                    # Search for the closing comment
                    n = s.find('*/', n2+2)
                    if n==-1:
                        self.inside_comment = True
                        start = slength
                    else:
                        yield (n-n2+2)*" "
                        start = n+2
                # '"'
                else:
                    if n3>start:
                        yield s[start:n3]
                    # Search for the closing apostrophes and yield the string
                    n = s.find('"', n3+1)
                    if n==-1:
                        # No closing apostrophes in the same line? This is
                        # actually an error
                        yield s[n3:]
                        start = slength
                    else:
                        n += 1
                        yield s[n3:n]
                        start = n
                
                        
                    
                    
    

######################################################################

if __name__=="__main__":
    import optparse
    
    op = optparse.OptionParser()
    op.add_option("-D", "--define", action="append", default=[],
                 help="Define a symbol")    
    op.add_option("-I", "--includedir", action="append", default=[],
                 help="Specify include paths")    
    
    opts, args = op.parse_args()
    p = PreProcessor(includedirs=opts.includedir, defines=map(lambda x: (x,None), opts.define))
    if len(args)==0:
        print p(sys.stdin)
    else:
        try:
            print p(file(args[0]))
        except IOError, e:
            print e
