[29] | 1 | // (C) Copyright Jonathan Turkanis 2005. |
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| 2 | // Distributed under the Boost Software License, Version 1.0. (See accompanying |
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| 3 | // file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt.) |
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| 4 | |
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| 5 | // See http://www.boost.org/libs/iostreams for documentation. |
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| 6 | |
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| 7 | // Adapted from an example of James Kanze, with suggestions from Rob Stewart. |
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| 8 | // See http://www.gabi-soft.fr/codebase-en.html. |
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| 9 | |
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| 10 | #ifndef BOOST_IOSTREAMS_TAB_EXPANDING_FILTER_HPP_INCLUDED |
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| 11 | #define BOOST_IOSTREAMS_TAB_EXPANDING_FILTER_HPP_INCLUDED |
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| 12 | |
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| 13 | #include <cassert> |
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| 14 | #include <cstdio> // EOF. |
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| 15 | #include <iostream> // cin, cout. |
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| 16 | #include <boost/iostreams/concepts.hpp> |
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| 17 | #include <boost/iostreams/filter/stdio.hpp> |
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| 18 | #include <boost/iostreams/operations.hpp> |
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| 19 | |
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| 20 | namespace boost { namespace iostreams { namespace example { |
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| 21 | |
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| 22 | class tab_expanding_stdio_filter : public stdio_filter { |
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| 23 | public: |
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| 24 | explicit tab_expanding_stdio_filter(int tab_size = 8) |
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| 25 | : tab_size_(tab_size), col_no_(0) |
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| 26 | { |
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| 27 | assert(tab_size > 0); |
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| 28 | } |
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| 29 | private: |
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| 30 | void do_filter() |
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| 31 | { |
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| 32 | int c; |
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| 33 | while ((c = std::cin.get()) != EOF) { |
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| 34 | if (c == '\t') { |
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| 35 | int spaces = tab_size_ - (col_no_ % tab_size_); |
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| 36 | for (; spaces > 0; --spaces) |
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| 37 | put_char(' '); |
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| 38 | } else { |
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| 39 | put_char(c); |
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| 40 | } |
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| 41 | } |
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| 42 | } |
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| 43 | void do_close() { col_no_ = 0; } |
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| 44 | void put_char(int c) |
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| 45 | { |
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| 46 | std::cout.put(c); |
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| 47 | if (c == '\n') { |
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| 48 | col_no_ = 0; |
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| 49 | } else { |
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| 50 | ++col_no_; |
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| 51 | } |
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| 52 | } |
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| 53 | int tab_size_; |
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| 54 | int col_no_; |
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| 55 | }; |
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| 56 | |
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| 57 | class tab_expanding_input_filter : public input_filter { |
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| 58 | public: |
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| 59 | explicit tab_expanding_input_filter(int tab_size = 8) |
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| 60 | : tab_size_(tab_size), col_no_(0), spaces_(0) |
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| 61 | { |
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| 62 | assert(tab_size > 0); |
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| 63 | } |
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| 64 | |
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| 65 | template<typename Source> |
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| 66 | int get(Source& src) |
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| 67 | { |
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| 68 | if (spaces_ > 0) { |
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| 69 | --spaces_; |
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| 70 | return get_char(' '); |
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| 71 | } |
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| 72 | |
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| 73 | int c; |
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| 74 | if ((c = iostreams::get(src)) == EOF || c == WOULD_BLOCK) |
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| 75 | return c; |
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| 76 | |
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| 77 | if (c != '\t') |
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| 78 | return get_char(c); |
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| 79 | |
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| 80 | // Found a tab. Call this filter recursively. |
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| 81 | spaces_ = tab_size_ - (col_no_ % tab_size_); |
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| 82 | return this->get(src); |
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| 83 | } |
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| 84 | |
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| 85 | template<typename Source> |
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| 86 | void close(Source&) |
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| 87 | { |
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| 88 | col_no_ = 0; |
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| 89 | spaces_ = 0; |
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| 90 | } |
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| 91 | private: |
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| 92 | int get_char(int c) |
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| 93 | { |
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| 94 | if (c == '\n') { |
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| 95 | col_no_ = 0; |
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| 96 | } else { |
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| 97 | ++col_no_; |
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| 98 | } |
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| 99 | return c; |
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| 100 | } |
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| 101 | int tab_size_; |
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| 102 | int col_no_; |
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| 103 | int spaces_; |
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| 104 | }; |
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| 105 | |
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| 106 | class tab_expanding_output_filter : public output_filter { |
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| 107 | public: |
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| 108 | explicit tab_expanding_output_filter(int tab_size = 8) |
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| 109 | : tab_size_(tab_size), col_no_(0), spaces_(0) |
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| 110 | { |
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| 111 | assert(tab_size > 0); |
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| 112 | } |
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| 113 | |
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| 114 | template<typename Sink> |
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| 115 | bool put(Sink& dest, int c) |
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| 116 | { |
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| 117 | for (; spaces_ > 0; --spaces_) |
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| 118 | if (!put_char(dest, ' ')) |
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| 119 | return false; |
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| 120 | |
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| 121 | if (c == '\t') { |
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| 122 | spaces_ = tab_size_ - (col_no_ % tab_size_) - 1; |
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| 123 | return this->put(dest, ' '); |
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| 124 | } |
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| 125 | |
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| 126 | return put_char(dest, c); |
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| 127 | } |
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| 128 | |
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| 129 | template<typename Sink> |
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| 130 | void close(Sink&) |
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| 131 | { |
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| 132 | col_no_ = 0; |
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| 133 | spaces_ = 0; |
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| 134 | } |
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| 135 | private: |
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| 136 | template<typename Sink> |
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| 137 | bool put_char(Sink& dest, int c) |
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| 138 | { |
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| 139 | if (!iostreams::put(dest, c)) |
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| 140 | return false; |
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| 141 | if (c != '\n') |
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| 142 | ++col_no_; |
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| 143 | else |
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| 144 | col_no_ = 0; |
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| 145 | return true; |
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| 146 | } |
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| 147 | int tab_size_; |
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| 148 | int col_no_; |
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| 149 | int spaces_; |
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| 150 | }; |
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| 151 | |
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| 152 | } } } // End namespaces example, iostreams, boost. |
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| 153 | |
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| 154 | #endif // #ifndef BOOST_IOSTREAMS_TAB_EXPANDING_FILTER_HPP_INCLUDED |
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