问题
I am wondering where I can find C tutorial/example of using AntLR. All I found is using Java language.
I am focusing to find a main function which use the parser and lexer generated by AntLR.
回答1:
Take a look at this document
And here is an example:
// Example of a grammar for parsing C sources,
// Adapted from Java equivalent example, by Terence Parr
// Author: Jim Idle - April 2007
// Permission is granted to use this example code in any way you want, so long as
// all the original authors are cited.
//
// set ts=4,sw=4
// Tab size is 4 chars, indent is 4 chars
// Notes: Although all the examples provided are configured to be built
// by Visual Studio 2005, based on the custom build rules
// provided in $(ANTLRSRC)/code/antlr/main/runtime/C/vs2005/rulefiles/antlr3.rules
// there is no reason that this MUST be the case. Provided that you know how
// to run the antlr tool, then just compile the resulting .c files and this
// file together, using say gcc or whatever: gcc *.c -I. -o XXX
// The C code is generic and will compile and run on all platforms (please
// report any warnings or errors to the antlr-interest newsgroup (see www.antlr.org)
// so that they may be corrected for any platform that I have not specifically tested.
//
// The project settings such as additional library paths and include paths have been set
// relative to the place where this source code sits on the ANTLR perforce system. You
// may well need to change the settings to locate the includes and the lib files. UNIX
// people need -L path/to/antlr/libs -lantlr3c (release mode) or -lantlr3cd (debug)
//
// Jim Idle (jimi cut-this at idle ws)
//
// You may adopt your own practices by all means, but in general it is best
// to create a single include for your project, that will include the ANTLR3 C
// runtime header files, the generated header files (all of which are safe to include
// multiple times) and your own project related header files. Use <> to include and
// -I on the compile line (which vs2005 now handles, where vs2003 did not).
//
#include <C.h>
// Main entry point for this example
//
int ANTLR3_CDECL
main (int argc, char *argv[])
{
// Now we declare the ANTLR related local variables we need.
// Note that unless you are convinced you will never need thread safe
// versions for your project, then you should always create such things
// as instance variables for each invocation.
// -------------------
// Name of the input file. Note that we always use the abstract type pANTLR3_UINT8
// for ASCII/8 bit strings - the runtime library guarantees that this will be
// good on all platforms. This is a general rule - always use the ANTLR3 supplied
// typedefs for pointers/types/etc.
//
pANTLR3_UINT8 fName;
// The ANTLR3 character input stream, which abstracts the input source such that
// it is easy to provide input from different sources such as files, or
// memory strings.
//
// For an ASCII/latin-1 memory string use:
// input = antlr3NewAsciiStringInPlaceStream (stringtouse, (ANTLR3_UINT64) length, NULL);
//
// For a UCS2 (16 bit) memory string use:
// input = antlr3NewUCS2StringInPlaceStream (stringtouse, (ANTLR3_UINT64) length, NULL);
//
// For input from a file, see code below
//
// Note that this is essentially a pointer to a structure containing pointers to functions.
// You can create your own input stream type (copy one of the existing ones) and override any
// individual function by installing your own pointer after you have created the standard
// version.
//
pANTLR3_INPUT_STREAM input;
// The lexer is of course generated by ANTLR, and so the lexer type is not upper case.
// The lexer is supplied with a pANTLR3_INPUT_STREAM from whence it consumes its
// input and generates a token stream as output.
//
pCLexer lxr;
// The token stream is produced by the ANTLR3 generated lexer. Again it is a structure based
// API/Object, which you can customise and override methods of as you wish. a Token stream is
// supplied to the generated parser, and you can write your own token stream and pass this in
// if you wish.
//
pANTLR3_COMMON_TOKEN_STREAM tstream;
// The C parser is also generated by ANTLR and accepts a token stream as explained
// above. The token stream can be any source in fact, so long as it implements the
// ANTLR3_TOKEN_SOURCE interface. In this case the parser does not return anything
// but it can of course specify any kind of return type from the rule you invoke
// when calling it.
//
pCParser psr;
// Create the input stream based upon the argument supplied to us on the command line
// for this example, the input will always default to ./input if there is no explicit
// argument.
//
if (argc < 2 || argv[1] == NULL)
{
fName =(pANTLR3_UINT8)"./input"; // Note in VS2005 debug, working directory must be configured
}
else
{
fName = (pANTLR3_UINT8)argv[1];
}
// Create the input stream using the supplied file name
// (Use antlr3AsciiFileStreamNew for UCS2/16bit input).
//
input = antlr3AsciiFileStreamNew(fName);
// The input will be created successfully, providing that there is enough
// memory and the file exists etc
//
if ( input == NULL)
{
fprintf(stderr, "Failed to open file %s\n", (char *)fName);
exit(1);
}
// Our input stream is now open and all set to go, so we can create a new instance of our
// lexer and set the lexer input to our input stream:
// (file | memory | ?) --> inputstream -> lexer --> tokenstream --> parser ( --> treeparser )?
//
lxr = CLexerNew(input); // CLexerNew is generated by ANTLR
// Need to check for errors
//
if ( lxr == NULL )
{
fprintf(stderr, "Unable to create the lexer due to malloc() failure1\n");
exit(1);
}
// Our lexer is in place, so we can create the token stream from it
// NB: Nothing happens yet other than the file has been read. We are just
// connecting all these things together and they will be invoked when we
// call the parser rule. ANTLR3_SIZE_HINT can be left at the default usually
// unless you have a very large token stream/input. Each generated lexer
// provides a token source interface, which is the second argument to the
// token stream creator.
// Note that even if you implement your own token structure, it will always
// contain a standard common token within it and this is the pointer that
// you pass around to everything else. A common token as a pointer within
// it that should point to your own outer token structure.
//
tstream = antlr3CommonTokenStreamSourceNew(ANTLR3_SIZE_HINT, TOKENSOURCE(lxr));
if (tstream == NULL)
{
fprintf(stderr, "Out of memory trying to allocate token stream\n");
exit(1);
}
// Finally, now that we have our lexer constructed, we can create the parser
//
psr = CParserNew(tstream); // CParserNew is generated by ANTLR3
if (psr == NULL)
{
fprintf(stderr, "Out of memory trying to allocate parser\n");
exit(ANTLR3_ERR_NOMEM);
}
// We are all ready to go. Though that looked complicated at first glance,
// I am sure, you will see that in fact most of the code above is dealing
// with errors and there isn't really that much to do (isn't this always the
// case in C? ;-).
//
// So, we now invoke the parser. All elements of ANTLR3 generated C components
// as well as the ANTLR C runtime library itself are pseudo objects. This means
// that they are represented as pointers to structures, which contain any
// instance data they need, and a set of pointers to other interfaces or
// 'methods'. Note that in general, these few pointers we have created here are
// the only things you will ever explicitly free() as everything else is created
// via factories, that allocated memory efficiently and free() everything they use
// automatically when you close the parser/lexer/etc.
//
// Note that this means only that the methods are always called via the object
// pointer and the first argument to any method, is a pointer to the structure itself.
// It also has the side advantage, if you are using an IDE such as VS2005 that can do it
// that when you type ->, you will see a list of tall the methods the object supports.
//
psr->translation_unit(psr);
// We did not return anything from this parser rule, so we can finish. It only remains
// to close down our open objects, in the reverse order we created them
//
psr ->free (psr); psr = NULL;
tstream ->free (tstream); tstream = NULL;
lxr ->free (lxr); lxr = NULL;
input ->close (input); input = NULL;
return 0;
}
回答2:
contrapunctus.net/blog/2012/antlr-c a simple google would suffice. Note however, the example is C++ I don't think ANTLR supports PURE C – Aniket Jan 1 at 1:56
来源：https://stackoverflow.com/questions/20859947/c-example-of-using-antlr