xref: /aosp_15_r20/external/antlr/runtime/C/doxygen/buildrec.dox (revision 16467b971bd3e2009fad32dd79016f2c7e421deb)

/// \page buildrec How to build Generated C Code
///
/// \section generated Generated Files
///
/// The antlr tool jar, run against a grammar file that targets the C language, will generate the following files
/// according to whether your grammar file contains a lexer, parser, combined or treeparser specification.
/// Your grammar file name and the subject of the grammar line in your file are expected to match. Here the generic name G is used:
///
/// <table>
/// <tr>
/// <th> Suffix </th>
/// <th> Generated files </th>
/// </tr>
/// <tr>
/// <td> lexer grammar (G.g3l) </td>
/// <td> GLexer.c GLexer.h</td>
/// </tr>
/// <tr>
/// <td> parser grammar (G.g3p) </td>
/// <td> GParser.c GParser.h </td>
/// </tr>
/// <tr>
/// <td> grammar G (G.g3pl) </td>
/// <td> GParser.c GParser.h GLexer.c GLexer.h</td>
/// </tr>
/// <tr>
/// <td> tree grammar G; (G.g3t) </td>
/// <td> G.c G.h </td>
/// </tr>
/// </table>
///
/// The generated .c files reference the .h files using <G.h>, so you must use <code>-I.</code> on your compiler command line
/// (or include the current directory in your include paths in Visual Studio). Additionally, the generated .h files reference
/// <code>antlr3.h</code>, so you must use <code>-I/path/to/antlr/include</code> (E.g. <code>-I /usr/local/include</code>) to reference the standard ANTLR include files.
///
/// In order to reference the library file at compile time (you can/should only reference one) you need to use the
/// <code>-L/path/to/antlr/lib</code> (E.g. <code>-L /usr/local/lib</code>) on Unix, or add the path to your "Additional Library Path" in
/// Visual Studio. You also need to specify the library using <code>-L</code> on Unix (E.g. <code>-L /usr/local/lib -l antlr3c</code>) or add <code>antlr3c_dll.lib</code>
/// to your Additional Library Dependencies in Visual Studio.
///
/// In case it isn't obvious, the generated files may be used to produce either a library or an executable (.EXE on Windows) file.
///
/// If you use the shared version of the libraries, DLL or .so/.so/.a then you must ship the library with your
/// application must run in an environment whereby the library can be found by the runtime linker/loader.
/// This usually involves specifying the directory in which the library lives to an environment variable.
/// On Windows, X:{yourwininstalldir}\system32 will be searched automatically.
///
/// \section invoke Invoking Your Generated Recognizer
///
/// In order to run your lexer/parser/tree parser combination, you will need a small function (or main)
/// function that controls the sequence of events, from reading the input file or string, through to
/// invoking the tree parser(s) and retrieving the results. See "Using the ANTLR3C C Target" for more
/// detailed instructions, but if you just want to get going as fast as possible, study the following
/// code example.
///
/// \code
///
/// // 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    <treeparser.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 privide inpput from different sources such as files, or
///     // memory strings.
///     //
///     // For an 8Bit/latin-1/etc memory string use:
///     //	    input = antlr3New8BitStringInPlaceStream (stringtouse, (ANTLR3_UINT32) length, NULL);
///     //
///     // For a UTF16 memory string use:
///     //	    input = antlr3NewUTF16StringInPlaceStream (stringtouse, (ANTLR3_UINT32) 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. This is the ctx (CTX macro) pointer
///		// for your lexer.
///     //
///     pLangLexer			    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 Lang 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. This is the ctx (CTX macro) pointer for your parser.
///     //
///     pLangParser			    psr;
///
///     // The parser produces an AST, which is returned as a member of the return type of
///     // the starting rule (any rule can start first of course). This is a generated type
///     // based upon the rule we start with.
///     //
///     LangParser_decl_return	    langAST;
///
///
///     // The tree nodes are managed by a tree adaptor, which doles
///     // out the nodes upon request. You can make your own tree types and adaptors
///     // and override the built in versions. See runtime source for details and
///     // eventually the wiki entry for the C target.
///     //
///     pANTLR3_COMMON_TREE_NODE_STREAM	nodes;
///
///     // Finally, when the parser runs, it will produce an AST that can be traversed by the
///     // the tree parser: c.f. LangDumpDecl.g3t This is the ctx (CTX macro) pointer for your
///		// tree parser.
///     //
///     pLangDumpDecl		    treePsr;
///
///     // 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 antlr38BitFileStreamNew for UTF16 input).
///     //
///     input	= antlr38BitFileStreamNew(fName);
///
///     // The input will be created successfully, providing that there is enough
///     // memory and the file exists etc
///     //
///     if ( input == NULL )
///     {
/// 			ANTLR3_FPRINTF(stderr, "Unable to open file %s due to malloc() failure1\n", (char *)fName);
///     }
///
///     // 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	    = LangLexerNew(input);	    // CLexerNew is generated by ANTLR
///
///     // Need to check for errors
///     //
///     if ( lxr == NULL )
///     {
/// 			ANTLR3_FPRINTF(stderr, "Unable to create the lexer due to malloc() failure1\n");
/// 			exit(ANTLR3_ERR_NOMEM);
///     }
///
///     // 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 tha 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, lxr->pLexer->tokSource);
///
///     if (tstream == NULL)
///     {
/// 		ANTLR3_FPRINTF(stderr, "Out of memory trying to allocate token stream\n");
/// 		exit(ANTLR3_ERR_NOMEM);
///     }
///
///     // Finally, now that we have our lexer constructed, we can create the parser
///     //
///     psr	    = LangParserNew(tstream);  // CParserNew is generated by ANTLR3
///
///     if (psr == NULL)
///     {
/// 		ANTLR3_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 allocate 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 all the methods the object supports.
///     //
///     langAST = psr->decl(psr);
///
///     // If the parser ran correctly, we will have a tree to parse. In general I recommend
///     // keeping your own flags as part of the error trapping, but here is how you can
///     // work out if there were errors if you are using the generic error messages
///     //
/// 	if (psr->pParser->rec->errorCount > 0)
/// 	{
/// 		ANTLR3_FPRINTF(stderr, "The parser returned %d errors, tree walking aborted.\n", psr->pParser->rec->errorCount);
///
/// 	}
/// 	else
/// 	{
/// 		nodes	= antlr3CommonTreeNodeStreamNewTree(langAST.tree, ANTLR3_SIZE_HINT); // sIZE HINT WILL SOON BE DEPRECATED!!
///
/// 		// Tree parsers are given a common tree node stream (or your override)
/// 		//
/// 		treePsr	= LangDumpDeclNew(nodes);
///
/// 		treePsr->decl(treePsr);
/// 		nodes   ->free  (nodes);	    nodes	= NULL;
/// 		treePsr ->free  (treePsr);	    treePsr	= NULL;
/// 	}
///
/// 	// 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;
/// }
/// \endcode
///