1 //===-- A class for number to string mappings -------------------*- C++ -*-===//
2 //
3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4 // See https://llvm.org/LICENSE.txt for license information.
5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6 //
7 //===----------------------------------------------------------------------===//
8
9 #ifndef LLVM_LIBC_SRC___SUPPORT_STRINGUTIL_MESSAGE_MAPPER_H
10 #define LLVM_LIBC_SRC___SUPPORT_STRINGUTIL_MESSAGE_MAPPER_H
11
12 #include "src/__support/CPP/array.h"
13 #include "src/__support/CPP/optional.h"
14 #include "src/__support/CPP/string_view.h"
15 #include "src/__support/macros/config.h"
16 #include <stddef.h>
17
18 namespace LIBC_NAMESPACE_DECL {
19
20 struct MsgMapping {
21 int num;
22 cpp::string_view msg;
23
MsgMappingMsgMapping24 constexpr MsgMapping() : num(0), msg() { ; }
25
MsgMappingMsgMapping26 constexpr MsgMapping(int init_num, const char *init_msg)
27 : num(init_num), msg(init_msg) {
28 ;
29 }
30 };
31
32 template <size_t N> using MsgTable = cpp::array<MsgMapping, N>;
33
total_str_len(const MsgTable<N> & table)34 template <size_t N> constexpr size_t total_str_len(const MsgTable<N> &table) {
35 size_t total = 0;
36 for (size_t i = 0; i < table.size(); ++i) {
37 // add 1 for the null terminator.
38 total += table[i].msg.size() + 1;
39 }
40 return total;
41 }
42
max_key_val(const MsgTable<N> & table)43 template <size_t N> constexpr size_t max_key_val(const MsgTable<N> &table) {
44 int max = 0;
45 for (size_t i = 0; i < table.size(); ++i) {
46 if (table[i].num > max) {
47 max = table[i].num;
48 }
49 }
50 // max will never be negative since the starting value is 0. This is good,
51 // since it's used as a length.
52 return static_cast<size_t>(max);
53 }
54
55 template <size_t ARR_SIZE, size_t TOTAL_STR_LEN> class MessageMapper {
56 int msg_offsets[ARR_SIZE] = {-1};
57 char string_array[TOTAL_STR_LEN] = {'\0'};
58
59 public:
MessageMapper(const MsgTable<N> & table)60 template <size_t N> constexpr MessageMapper(const MsgTable<N> &table) {
61 cpp::string_view string_mappings[ARR_SIZE] = {""};
62 for (size_t i = 0; i < table.size(); ++i)
63 string_mappings[table[i].num] = table[i].msg;
64
65 int string_array_index = 0;
66 for (size_t cur_num = 0; cur_num < ARR_SIZE; ++cur_num) {
67 if (string_mappings[cur_num].size() != 0) {
68 msg_offsets[cur_num] = string_array_index;
69 // No need to replace with proper strcpy, this is evaluated at compile
70 // time.
71 for (size_t i = 0; i < string_mappings[cur_num].size() + 1;
72 ++i, ++string_array_index) {
73 string_array[string_array_index] = string_mappings[cur_num][i];
74 }
75 } else {
76 msg_offsets[cur_num] = -1;
77 }
78 }
79 }
80
get_str(int num)81 cpp::optional<cpp::string_view> get_str(int num) const {
82 if (num >= 0 && static_cast<size_t>(num) < ARR_SIZE &&
83 msg_offsets[num] != -1) {
84 return {string_array + msg_offsets[num]};
85 } else {
86 return cpp::optional<cpp::string_view>();
87 }
88 }
89 };
90
91 template <size_t N1, size_t N2>
92 constexpr MsgTable<N1 + N2> operator+(const MsgTable<N1> &t1,
93 const MsgTable<N2> &t2) {
94 MsgTable<N1 + N2> res{};
95 for (size_t i = 0; i < N1; ++i)
96 res[i] = t1[i];
97 for (size_t i = 0; i < N2; ++i)
98 res[N1 + i] = t2[i];
99 return res;
100 }
101
102 } // namespace LIBC_NAMESPACE_DECL
103
104 #endif // LLVM_LIBC_SRC___SUPPORT_STRINGUTIL_MESSAGE_MAPPER_H
105