如何运行Wave快速入门示例？

问题描述

（源自this问题。）

我尝试使用this示例失败。

我的尝试是复制并轻松编辑链接上的代码。结果是这样的（我在Boost网站上留下了评论，以使我的编辑内容与原始内容的比较更加容易）：

#include <boost/wave.hpp>
#include <boost/wave/cpplexer/cpp_lex_iterator.hpp>

int main() {
    // The following preprocesses a given input file.
    // Open the file and read it into a string variable
    std::string input("int main() { std::cout << \"Hello world\"; }");
    // The template boost::wave::cpplexer::lex_token<> is the  
    // token type to be used by the Wave library.
    // This token type is one of the central types throughout 
    // the library,because it is a template parameter to some 
    // of the public classes and templates and it is returned 
    // from the iterators.
    // The template boost::wave::cpplexer::lex_iterator<> is
    // the lexer iterator to use as the token source for the
    // preprocessing engine. In this case this is parameterized
    // with the token type.
    typedef boost::wave::cpplexer::lex_iterator<
            boost::wave::cpplexer::lex_token<> >
        lex_iterator_type;
    typedef boost::wave::context<
            std::string::iterator,lex_iterator_type>
        context_type;

    context_type ctx(input.begin(),input.end(),"preproc.cpp");

    // At this point you may want to set the parameters of the
    // preprocessing as include paths and/or predefined macros.
    //ctx.add_include_path("...");
    //ctx.add_macro_deFinition("...");

    // Get the preprocessor iterators and use them to generate 
    // the token sequence.
    context_type::iterator_type first = ctx.begin();
    context_type::iterator_type last = ctx.end();

    // The input stream is preprocessed for you during iteration
    // over [first,last)
    while (first != last) {
        std::cout << (*first).get_value();
        ++first;
    }
}

我可以成功地编译

g++ -std=c++17 -lboost_thread -lboost_filesystem -lboost_wave source.cpp

但是在运行可执行文件时出现此错误

terminate called after throwing an instance of 'boost::wrapexcept<boost::wave::preprocess_exception>'
  what():  boost::wave::preprocess_exception
Aborted (core dumped)

如评论中所建议，将std::cout << (*first).get_value();更改为std::cout << (*first).get_value() << '\n';时，很明显在EOF上引发了异常。仅凭猜测，我尝试在\n的末尾添加input，程序运行正常，没有任何误解。

但是，当我将代码恢复为链接的示例时，是从文件中读取input而不是对其进行硬编码，

    //std::string input("int main() { std::cout << \"Hello world\"; }");
    std::ifstream instream("somefile.cpp");
    std::string input(
        std::istreambuf_iterator<char>(instream.rdbuf()),std::istreambuf_iterator<char>());

然后我遇到了同样的错误。

解决方法

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