diff options
Diffstat (limited to 'libbutl/pager.hxx')
-rw-r--r-- | libbutl/pager.hxx | 84 |
1 files changed, 84 insertions, 0 deletions
diff --git a/libbutl/pager.hxx b/libbutl/pager.hxx new file mode 100644 index 0000000..12a6670 --- /dev/null +++ b/libbutl/pager.hxx @@ -0,0 +1,84 @@ +// file : libbutl/pager.hxx -*- C++ -*- +// license : MIT; see accompanying LICENSE file + +#pragma once + +#include <string> +#include <vector> +#include <iostream> + +#include <libbutl/process.hxx> +#include <libbutl/fdstream.hxx> + +#include <libbutl/export.hxx> + +namespace butl +{ + // Try to run the output through a pager program, such as more or less (no + // pun intended, less is used by default). If the default pager program is + // used, then the output is indented so that 80-character long lines will + // appear centered in the terminal. If the default pager program fails to + // start, then the output is sent directly to STDOUT. + // + // If the pager program is specified and is empty, then no pager is used + // and the output is sent directly to STDOUT. + // + // Throw std::system_error if there are problems with the pager program. + // + // Typical usage: + // + // try + // { + // pager p ("help for foo"); + // ostream& os (p.stream ()); + // + // os << "Foo is such and so ..."; + // + // if (!p.wait ()) + // ... // Pager program returned non-zero status. + // } + // catch (const std::system_error& e) + // { + // cerr << "pager error: " << e << endl; + // } + // + class LIBBUTL_SYMEXPORT pager: protected std::streambuf + { + public: + ~pager () {wait (true);} + + // If verbose is true, then print (to STDERR) the pager command line. + // + pager (const std::string& name, + bool verbose = false, + const std::string* pager = nullptr, + const std::vector<std::string>* pager_options = nullptr); + + std::ostream& + stream () {return os_.is_open () ? os_ : std::cout;} + + bool + wait (bool ignore_errors = false); + + // The streambuf output interface that implements indentation. You can + // override it to implement custom output pre-processing. + // + protected: + using int_type = std::streambuf::int_type; + using traits_type = std::streambuf::traits_type; + + virtual int_type + overflow (int_type); + + virtual int + sync (); + + private: + process p_; + ofdstream os_; + + std::string indent_; + int_type prev_ = '\n'; // Previous character. + std::streambuf* buf_ = nullptr; + }; +} |