term: add trivial ANSI colour escapes

Makefile.am

@@ -247,6 +247,8 @@ UTIL_FILES   =			\
     tap.cpp			\
     tap.hpp			\
     tap.ipp			\
+    term.cpp			\
+    term.hpp			\
     time.cpp			\
     time.hpp			\
     tuple.cpp			\

term.cpp

@@ -0,0 +1,136 @@
+/*
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ *
+ * Copyright 2016 Danny Robson <danny@nerdcruft.net>
+ */
+
+#include "./term.hpp"
+
+#include "./string.hpp"
+
+#include <boost/filesystem.hpp>
+#include <cstdlib>
+#include <stdexcept>
+
+using util::term::csi::graphics;
+
+
+static const boost::filesystem::path DEFAULT_SEARCH_DIR = "/usr/share/terminfo";
+
+constexpr char util::term::csi::code::CSI;
+
+const graphics graphics::RESET (0);
+
+
+///////////////////////////////////////////////////////////////////////////////
+// find the terminfo path within a directory, for a key
+//
+// throws an exception if not found
+static
+boost::filesystem::path
+find_terminfo_path (const boost::filesystem::path &dir,
+                    const std::string &key)
+{
+    const char letter[2] = { key[0], '\0' };
+    auto candidate = dir / letter / key;
+
+    if (!boost::filesystem::is_directory (candidate))
+        throw std::runtime_error ("path not found");
+
+    return candidate;
+}
+
+
+//-----------------------------------------------------------------------------
+// find the terminfo path for a given key.
+//
+// throws an exception if not found
+static
+boost::filesystem::path
+find_terminfo_path (const std::string &key)
+{
+    // check if the path is explicitly listed. must not fall through.
+    if (const char *dir = getenv ("TERMINFO")) {
+        return find_terminfo_path (dir, key);
+    }
+
+    // check if we have a path at $HOME. falls through.
+    if (const char *home = getenv ("HOME")) {
+        boost::filesystem::path HOME (home);
+        try {
+            return find_terminfo_path (HOME / ".terminfo", key);
+        } catch (...) { }
+    }
+
+    // check colon seperated list in TERMINFO_DIRS
+    if (const char *dirs = getenv ("TERMINFO_DIRS")) {
+        auto tok = util::make_tokeniser (dirs, ':');
+
+        for (auto i: tok) {
+            try {
+                return find_terminfo_path (
+                    i.empty () ?
+                    DEFAULT_SEARCH_DIR :
+                    boost::filesystem::path (i.cbegin (), i.cend ()), key
+                );
+            } catch (...) { }
+        }
+    }
+
+    return find_terminfo_path ("/usr/share/terminfo", key);
+}
+
+
+///////////////////////////////////////////////////////////////////////////////
+bool
+util::term::has_csi_support (void)
+{
+    // HACK: this will do until we get a terminfo/termcap reader
+    return getenv ("TERM") == std::string ("XTERM");
+}
+
+
+///////////////////////////////////////////////////////////////////////////////
+graphics::graphics (layer _layer, hue _hue):
+    m_value (_layer + _hue)
+{ ; }
+
+
+//-----------------------------------------------------------------------------
+graphics::graphics (char _value):
+    m_value (_value)
+{ ; }
+
+
+///////////////////////////////////////////////////////////////////////////////
+char
+graphics::value (void) const
+{
+    return m_value;
+}
+
+
+//-----------------------------------------------------------------------------
+char
+graphics::value (char _value)
+{
+    return m_value = _value;
+}
+
+
+///////////////////////////////////////////////////////////////////////////////
+std::ostream&
+util::term::csi::operator<< (std::ostream &os, graphics g)
+{
+    return os << code::CSI << '[' << +g.value () << decltype(g)::terminator;
+}

term.hpp

@@ -0,0 +1,68 @@
+/*
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ *
+ * Copyright 2016 Danny Robson <danny@nerdcruft.net>
+ */
+
+#ifndef __UTIL_TERM_HPP
+#define __UTIL_TERM_HPP
+
+#include <ostream>
+
+namespace util { namespace term {
+    bool has_csi_support (void);
+
+    namespace csi {
+        struct code {
+            static constexpr char CSI = '\x1B';
+        };
+
+
+        struct graphics : public code {
+            static constexpr char terminator = 'm';
+
+            enum layer {
+                FOREGROUND = 30,
+                BACKGROUND = 40
+            };
+
+            enum hue {
+                BLACK   = 0,
+                RED     = 1,
+                GREEN   = 2,
+                YELLOW  = 3,
+                BLUE    = 4,
+                MAGENTA = 5,
+                CYAN    = 6,
+                WHITE   = 7,
+            };
+
+            graphics (layer, hue);
+            explicit graphics (char value);
+
+            char value (void) const;
+            char value (char);
+
+            static const graphics RESET;
+
+        private:
+            char m_value;
+        };
+
+
+        std::ostream& operator<< (std::ostream&, code);
+        std::ostream& operator<< (std::ostream&, graphics);
+    }
+} }
+
+#endif