From 3f46775b35bd21bec449f075822ade4f12d876b5 Mon Sep 17 00:00:00 2001
From: Andreas Tsouchlos <an.tsouchlos@gmail.com>
Date: Thu, 25 Nov 2021 11:04:24 +0100
Subject: [PATCH] Moved functions to appropriate header files; Implemented
 const char* formatting

---
 inc/ConstString.h |  38 ---------
 inc/Logger.h      |   1 -
 inc/format.h      | 201 ++++++++++++++++++----------------------------
 inc/parse.h       |   1 -
 inc/types.h       |  31 +++++++
 inc/utility.h     |  25 ++++++
 src/main.cpp      |   2 +-
 7 files changed, 133 insertions(+), 166 deletions(-)
 delete mode 100644 inc/ConstString.h

diff --git a/inc/ConstString.h b/inc/ConstString.h
deleted file mode 100644
index c531dcd..0000000
--- a/inc/ConstString.h
+++ /dev/null
@@ -1,38 +0,0 @@
-#ifndef LOGGER_CONSTSTRING_H
-#define LOGGER_CONSTSTRING_H
-
-
-#include <array>
-
-
-namespace detail {
-
-
-template <std::size_t N>
-class ConstString {
-public:
-    constexpr ConstString(const char (&content)[N]) noexcept {
-        std::copy(std::begin(content), std::end(content),
-                  std::begin(m_content));
-    }
-
-    constexpr char operator[](std::size_t index) const noexcept {
-        return m_content[index];
-    }
-
-    constexpr std::size_t size() const noexcept {
-        return N - 1;
-    }
-
-    std::array<char, N> m_content;
-};
-
-
-template <std::size_t N>
-ConstString(const char (&)[N]) -> ConstString<N>;
-
-
-} // namespace detail
-
-
-#endif // LOGGER_CONSTSTRING_H
diff --git a/inc/Logger.h b/inc/Logger.h
index bbe952e..bd06c88 100644
--- a/inc/Logger.h
+++ b/inc/Logger.h
@@ -7,7 +7,6 @@
 #include <tuple>
 
 #include <format.h>
-#include <ConstString.h>
 
 
 /*
diff --git a/inc/format.h b/inc/format.h
index 513aa89..a012e4b 100644
--- a/inc/format.h
+++ b/inc/format.h
@@ -4,30 +4,18 @@
 
 #include "parse.h"
 #include "utility.h"
+#include <cstring>
 
 
 namespace detail {
 
-template <fmt_node_t fmt_node, typename T>
-constexpr void check_fmt_params() {
-    static_assert(fmt_node.length > fmt_node.precision + 1,
-                  "Insufficient length for desired precision");
-}
 
+/*
+ *
+ * Utility functions
+ *
+ */
 
-template <auto t_ast>
-consteval int get_ast_output_len() {
-    unsigned result = 0;
-
-    for (const auto& ast_node : t_ast) {
-        if (ast_node.is_char())
-            ++result;
-        else
-            result += ast_node.get_node().length;
-    }
-
-    return result;
-}
 
 template <ConstString s>
 constexpr int get_output_len() {
@@ -37,87 +25,69 @@ constexpr int get_output_len() {
     return get_ast_output_len<parse_result.value>();
 }
 
-//// TODO: See if this is possible with <charconv>
-//// TODO: Steal some code from fmtlib
-//// TODO: In case of error, set chars to all 'f's
-// template <fmt_node_t fmt_node, std::integral arg_t>
-// constexpr std::array<char, fmt_node.length> format_arg(arg_t arg) {
-//     check_fmt_params<fmt_node, arg_t>();
-//
-//     auto result = get_init_array<fmt_node>();
-//
-//     unsigned offset = 0;
-//
-//     if (arg < 0) {
-//         result[0] = '-';
-//         arg       = -arg;
-//         ++offset;
-//     }
-//
-//     for (int i = result.size() - 1;
-//          (i >= static_cast<int>(offset)) && (arg > 0); --i) {
-//         result[i] = arg % 10 + 48;
-//         arg       = arg / 10;
-//     }
-//
-//     return result;
-// }
-//
-//// TODO: See if this is possible with <charconv>
-//// TODO: Steal some code from fmtlib
-//// TODO: In case of error, set chars to all 'f's
-// template <fmt_node_t fmt_node, std::floating_point arg_t>
-// constexpr std::array<char, fmt_node.length> format_arg(arg_t arg) {
-//     check_fmt_params<fmt_node, arg_t>();
-//
-//     constexpr unsigned point_index = fmt_node.length - fmt_node.precision -
-//     1; constexpr unsigned multiplier  = const_pow(10, fmt_node.precision);
-//
-//     auto result         = get_init_array<fmt_node>();
-//     result[point_index] = '.';
-//
-//
-//     arg = arg * multiplier;
-//
-//     for (int i = result.size() - 1;
-//          (i > static_cast<int>(point_index)) && (arg >= 1); --i) {
-//
-//         result[i] = static_cast<int>(arg) % 10 + 48;
-//         arg       = arg / 10;
-//     }
-//
-//     for (int i = point_index - 1; (i >= 0) && (arg >= 1); --i) {
-//         result[i] = static_cast<int>(arg) % 10 + 48;
-//         arg       = arg / 10;
-//     }
-//
-//     return result;
-// }
-//
-//// TODO: Steal some code from fmtlib
-//// TODO: In case of error, set chars to all 'f's
-// template <fmt_node_t fmt_node>
-// constexpr std::array<char, fmt_node.length> format_arg(const char* arg) {
-//     check_fmt_params<fmt_node, const char*>();
-//
-//     std::array<char, fmt_node.length> result;
-//
-//     for (auto& c : result) {
-//         if (*arg != '\0')
-//             c = *(arg++);
-//         else
-//             c = ' ';
-//     }
-//
-//     return result;
-// }
-//
-//
-// template <auto t_ast, unsigned t_ast_i = 0, unsigned t_result_i = 0,
-//           typename char_array_t>
-// constexpr char_array_t format_args(char_array_t result) {
-//     return result;
-// }
+template <fmt_node_t fmt_node, typename T>
+constexpr void check_fmt_params() {
+    static_assert(fmt_node.length > fmt_node.precision + 1,
+                  "Insufficient length for desired precision");
+}
+
+
+/*
+ *
+ * Type-specific formatting functions
+ *      (Most of this code is shamelessly stolen from fmtlib)
+ */
+
+
+// TODO
+
+
+/*
+ *
+ *  Formatting wrapper functions
+ *
+ */
+
+
+template <std::integral arg_t>
+constexpr void format_arg(char* dest, fmt_data_t fmt_data, arg_t) {
+    *(dest + fmt_data.position) = 'i';
+    //    dest = dest + fmt_data.position;
+    //    format_int(dest, fmt_data.length, arg);
+};
+template <std::floating_point arg_t>
+constexpr void format_arg(char* dest, fmt_data_t fmt_data, arg_t) {
+    dest    = dest + fmt_data.position;
+    *(dest) = 'f';
+    *(dest + fmt_data.length - fmt_data.precision - 1) = '.';
+};
+// TODO: Error handling
+constexpr void format_arg(char* dest, fmt_data_t fmt_data, const char* arg) {
+    const std::size_t len = const_strlen(arg);
+    if (len > fmt_data.length) return;
+
+    dest = dest + fmt_data.position + fmt_data.length - len;
+
+    if (!std::is_constant_evaluated()) {
+        std::memcpy(dest, arg, len);
+        return;
+    }
+    for (std::size_t i = 0; i < len; ++i) {
+        *(dest++) = *(arg++);
+    }
+};
+
+
+template <auto ast>
+constexpr void format_args(char*) {
+}
+
+template <auto fmt_data_array, typename first_arg_t, typename... args_t>
+constexpr void format_args(char* dest, first_arg_t first_arg, args_t... args) {
+    format_arg(dest, fmt_data_array[0], first_arg);
+    format_args<drop_first(fmt_data_array)>(dest, args...);
+}
+
 
 template <auto ast>
 consteval std::array<char, get_ast_output_len<ast>()> get_preproc_string() {
@@ -136,35 +106,16 @@ consteval std::array<char, get_ast_output_len<ast>()> get_preproc_string() {
 }
 
 
-template <std::integral arg_t>
-constexpr void format_arg(char* dest, fmt_data_t fmt_data, arg_t arg) {
-    *(dest + fmt_data.position) = 'i';
-//    dest = dest + fmt_data.position;
-//    format_int(dest, fmt_data.length, arg);
-};
-template <std::floating_point arg_t>
-constexpr void format_arg(char* dest, fmt_data_t fmt_data, arg_t) {
-    *(dest + fmt_data.position) = 'f';
-};
-constexpr void format_arg(char* dest, fmt_data_t fmt_data, const char*) {
-    *(dest + fmt_data.position) = 'c';
-};
-
-
-template <auto ast>
-constexpr void format_args(char*) {
-}
-
-template <auto fmt_data_array, typename first_arg_t, typename... args_t>
-constexpr void format_args(char* dest, first_arg_t first_arg, args_t... args) {
-    format_arg(dest, fmt_data_array[0], first_arg);
-    format_args<drop_first(fmt_data_array)>(dest, args...);
-}
-
-
 } // namespace detail
 
 
+/*
+ *
+ * Public API
+ *
+ */
+
+
 template <detail::ConstString s, typename... args_t>
 constexpr std::array<char, detail::get_output_len<s>()> format(args_t... args) {
     constexpr auto ast      = detail::parse_string<s>().value;
diff --git a/inc/parse.h b/inc/parse.h
index a9a1260..ab1a161 100644
--- a/inc/parse.h
+++ b/inc/parse.h
@@ -2,7 +2,6 @@
 #define LOGGER_PARSE_H
 
 
-#include "ConstString.h"
 #include "types.h"
 
 
diff --git a/inc/types.h b/inc/types.h
index d0fcd81..1bd9049 100644
--- a/inc/types.h
+++ b/inc/types.h
@@ -8,6 +8,37 @@
 namespace detail {
 
 
+/*
+ *
+ * Types used everywhere
+ *
+ */
+
+
+template <std::size_t N>
+class ConstString {
+public:
+    constexpr ConstString(const char (&content)[N]) noexcept {
+        std::copy(std::begin(content), std::end(content),
+                  std::begin(m_content));
+    }
+
+    constexpr char operator[](std::size_t index) const noexcept {
+        return m_content[index];
+    }
+
+    constexpr std::size_t size() const noexcept {
+        return N - 1;
+    }
+
+    std::array<char, N> m_content;
+};
+
+
+template <std::size_t N>
+ConstString(const char (&)[N]) -> ConstString<N>;
+
+
 /*
  *
  * Types used mainly in parsing
diff --git a/inc/utility.h b/inc/utility.h
index 284a3e4..42a2697 100644
--- a/inc/utility.h
+++ b/inc/utility.h
@@ -2,6 +2,8 @@
 #define LOGGER_UTILITY_H
 
 
+#include <cstring>
+
 #include "types.h"
 
 
@@ -95,6 +97,29 @@ drop_first(std::array<elem_t, t_n> array) {
 }
 
 
+template <auto t_ast>
+consteval int get_ast_output_len() {
+    unsigned result = 0;
+
+    for (const auto& ast_node : t_ast) {
+        if (ast_node.is_char())
+            ++result;
+        else
+            result += ast_node.get_node().length;
+    }
+
+    return result;
+}
+
+constexpr std::size_t const_strlen(const char* arg) {
+    if (std::is_constant_evaluated()) {
+        return *arg ? 1 + const_strlen(arg + 1) : 0;
+    } else {
+        return strlen(arg);
+    }
+}
+
+
 } // namespace detail
 
 
diff --git a/src/main.cpp b/src/main.cpp
index 65559b6..aa2f8fc 100644
--- a/src/main.cpp
+++ b/src/main.cpp
@@ -4,7 +4,7 @@
 
 
 int main() {
-    constexpr auto formatted = format<"Test: {:012.5} {} {:8}">(142.4334, "abc", -1234);
+    constexpr auto formatted = format<"Test: {:012.5} {} {:8}">(142.4334, "abcdef", -1234);
 
     for (const auto& c : formatted)
         std::cout << c;