The Wave library contains several samples illustrating how to use the different features. This section describes these samples and its main characteristics.
The quick_start sample shows a minimal way to use the Wave preprocessor library. It simply opens the file given as the first command line argument, preprocesses it assuming that there aren't any additional include paths or macros defined and outputs the textual representation of the tokens generated from the given input file. This sample may be used to introduce yourself to Wave, because it does not contain all the potential additional complexity exposed by more complex samples.
The lexed_tokens sample shows a minimal way to use the C++ lexing component of Wave without using the preprocessor. It opens the file specified as the first command line argument and prints out the contents of the tokens returned from the lexer.
The cpp_tokens sample dumps out the information contained within the tokens returned from the iterator supplied by the Wave library. It shows, how to use the Wave library in conjunction with custom lexer and custom token types. The lexer used within this sample is SLex  based, i.e. it is feeded during runtime (at startup) with the token definitions (regular expressions) and generates a resulting DFA table. This table is used for token identification and is saved to disc afterwards to avoid the table generation process at the next program startup. The name of the file to which the DFA table is saved is wave_slex_lexer.dfa.
The main advantage of this SLex based lexer if compared to the default Re2C  generated lexer is, that it provides not only the line information, where a particular token was recognized, but also the related column position. Otherwise the SLex based lexer is functionally fully compatible to the Re2C based one, i.e. you always may switch your application to use it, if you additionally need to get the column information back from the preprocessing.
Since no additional command line parameters are supported by this sample, it won't work well with include files, which aren't located in the same directory as the inspected input file. The command line syntax is straight forward:
The list_includes sample shows how the Wave library may be used to generate a include file dependency list for a particular input file. It completely depends on the default library configuration. The command line syntax for this sample is given below:
Usage: list_includes [options] file ...: -h [ --help ] : print out program usage (this message) -v [ --version ] : print the version number -I [ --path ] dir : specify additional include directory -S [ --syspath ] dir : specify additional system include directory
Please note though, that this sample will output only those include file names, which are visible to the preprocessor, i.e. given the following code snippet, only one of the two include file directives is triggered during preprocessing and for this reason only the corresponding file name is reported by the list_includes sample:
#if defined(INCLUDE_FILE_A) # include "file_a.h" #else # include "file_b.h" #endif
Because of its general usefulness the wave sample is not located in the sample directory of the library, but inside the tools directory of Boost. The wave sample is usable as a full fledged preprocessor executable on top of any other C++ compiler. It outputs the textual representation of the preprocessed tokens generated from a given input file. It is described in more details here.
The main point of the waveidl sample is to show, how a completely independent lexer type may be used in conjunction with the default token type of the Wave library. The lexer used in this sample is supposed to be used for an IDL language based preprocessor. It is based on the Re2C tool too, but recognizes a different set of tokens as the default C++ lexer contained within the Wave library. So this lexer does not recognize any keywords (except true and false, which are needed by the preprocessor itself). This is needed because there exist different IDL languages, where identifiers of one language may be keywords of others. Certainly this implies to postpone keyword identification after the preprocessing, but allows to use Wave for all of the IDL derivatives.
It is only possible to use the Wave library to write an IDL preprocessor, because the token sets for both languages are very similar. The tokens to be recognized by the waveidl IDL language preprocessor is nearly a complete subset of the full C++ token set.
The command line syntax usable for this sample is shown below:
Usage: waveidl [options] [@config-file(s)] file: Options allowed on the command line only: -h [ --help ] : print out program usage (this message) -v [ --version ] : print the version number -c [ --copyright ] : print out the copyright statement --config-file filepath : specify a config file (alternatively: @filepath) Options allowed additionally in a config file: -o [ --output ] path : specify a file to use for output instead of stdout -I [ --include ] path : specify an additional include directory -S [ --sysinclude ] syspath : specify an additional system include directory -D [ --define ] macro[=[value]] : specify a macro to define -P [ --predefine ] macro[=[value]] : specify a macro to predefine -U [ --undefine ] macro : specify a macro to undefine
Copyright © 2003-2005 Hartmut Kaiser
Distributed under the Boost Software License, Version 1.0. (See accompanying file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
Last updated: Sunday, May 15, 2005 12:23