From bdb39b82263b0bed5ee3c0fb6795e9d789f16bc4 Mon Sep 17 00:00:00 2001
From: Roland Conybeare <rconybeare@gmail.com>
Date: Wed, 17 Apr 2024 18:23:39 -0400
Subject: [PATCH] xo-indentlog: + hex printer

---
 include/xo/indentlog/print/hex.hpp | 144 +++++++++++++++++++++++++++++
 1 file changed, 144 insertions(+)
 create mode 100644 include/xo/indentlog/print/hex.hpp

diff --git a/include/xo/indentlog/print/hex.hpp b/include/xo/indentlog/print/hex.hpp
new file mode 100644
index 00000000..66a34084
--- /dev/null
+++ b/include/xo/indentlog/print/hex.hpp
@@ -0,0 +1,144 @@
+/** @file hex.hpp **/
+
+#pragma once
+
+#include <iostream>
+
+namespace xo {
+    /**
+       @class hex indentlog/print/hex.hpp
+
+       @brief Container for a (1-byte) value to be printed in hexadecimal
+
+       Example:
+       @code
+       #include "indentlog/print/hex.hpp"
+
+       std::ostream os = ...;
+       os << hex(16 + 63);        // output: 1f
+       os << hex(16 + 63, true);  // output: 1f(O)
+       @endcode
+    **/
+    struct hex {
+        /** @brief constructor;  create stream-inserter instance */
+        hex(std::uint8_t x, bool w_char = false) : x_{x}, with_char_{w_char} {}
+
+        /**
+           @brief print hexadecimal byte-value on to stream.
+           @param os   print on this stream.
+
+           @tparam Stream  typename for character stream.
+        **/
+        template <typename Stream>
+        void print(Stream & os) const {
+            std::uint8_t lo = x_ & 0xf;
+            std::uint8_t hi = x_ >> 4;
+
+            char lo_ch = (lo < 10) ? '0' + lo : 'a' + lo - 10;
+            char hi_ch = (hi < 10) ? '0' + hi : 'a' + hi - 10;
+
+            os << hi_ch << lo_ch;
+
+            if (with_char_) {
+                os << "(";
+                if (std::isprint(x_))
+                    os << static_cast<char>(x_);
+                else
+                    os << "?";
+                os << ")";
+            }
+        }
+
+    private:
+        /** @brief value to print (in hexadecimal) **/
+        std::uint8_t x_;
+        /** @brief if true, follow with ascii character encoding **/
+        bool with_char_;
+    };
+
+    /**
+       @brief stream inserter for an 8-bit quantity to be printed in hexadecimal.
+
+       @param os    print on this stream
+       @param ins   package for value to insert
+    **/
+    template<typename Stream>
+    Stream &
+    operator<< (Stream & os, hex const & ins) {
+        ins.print(os);
+        return os;
+    }
+
+    /**
+       @class hex_view indentlog/print/hex.hpp
+
+       @brief Container for a range (unowned) of 1-byte values to be printed in hexadecimal
+
+       Print a range of bytes on an arbitrary character stream.
+       Does not use @c iomanips, so will not alter stream formatting flags if used with @c iostream.
+
+       Example:
+       @code
+       #include "indentlog/print/hex.hpp"
+
+       std::ostream os = ...;
+       os << hex_view("hello", false); // output: [68 65 6c 6c 6f]
+       os << hex_view("hello", true);  // output: [68(h) 65(e) 6c(l) 6c(l) 6f(o)]
+       @endcode
+    **/
+    struct hex_view {
+        /** @brief constructor;  create stream-inserter instance for a range of bytes **/
+        hex_view(std::uint8_t const * lo, std::uint8_t const * hi, bool as_text)
+            : lo_{lo}, hi_{hi}, as_text_{as_text} {}
+        /** @brief constructor;  create stream-inserter instance for a range of chars **/
+        hex_view(char const * lo, char const * hi, bool as_text)
+            : lo_{reinterpret_cast<std::uint8_t const *>(lo)},
+              hi_{reinterpret_cast<std::uint8_t const *>(hi)},
+              as_text_{as_text} {}
+
+        /**
+           @brief print hexadecimal byte range on stream.
+           @param os print on this stream
+
+           @tparam Stream typename for character stream.
+        **/
+        template <typename Stream>
+        void print(Stream & os) const {
+            os << "[";
+            std::size_t i = 0;
+            for (std::uint8_t const * p = lo_; p < hi_; ++p) {
+                if (i > 0)
+                    os << " ";
+                os << hex(*p, as_text_);
+                ++i;
+            }
+            os << "]";
+        }
+
+    private:
+        /** @brief print byte range starting at this address **/
+        std::uint8_t const * lo_;
+        /** @brief print byte range up to (but not including) this address **/
+        std::uint8_t const * hi_;
+        /** @brief if true also print ascii encoding (for printable codes),
+         *  \c ? otherwise.  @see hex::with_char
+         **/
+        bool as_text_;
+    };
+
+    /**
+       @brief stream inserter for a range of 1-byte values to be printed in hexadecimal
+
+       @param os    print on this stream.
+       @param ins   (container for) values to insert.
+    **/
+    template <typename Stream>
+    Stream &
+    operator<< (Stream & os, hex_view const & ins) {
+        ins.print(os);
+        return os;
+    }
+
+} /*namespace xo*/
+
+/* end hex.hpp */