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tools: refactor js2c.cc to use c++20
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PR-URL: #54849
Reviewed-By: James M Snell <[email protected]>
Reviewed-By: Daniel Lemire <[email protected]>
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@anonrig
anonrig authored Sep 19, 2024
1 parent 291d90a commit cde6dcc
Showing 1 changed file with 64 additions and 52 deletions.
116 changes: 64 additions & 52 deletions tools/js2c.cc
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Original file line number Diff line number Diff line change
@@ -1,13 +1,11 @@
#include <algorithm>
#include <array>
#include <cassert>
#include <cctype>
#include <cinttypes>
#include <cstdarg>
#include <cstdio>
#include <functional>
#include <iostream>
#include <map>
#include <set>
#include <string>
#include <string_view>
#include <vector>
Expand Down Expand Up @@ -72,42 +70,24 @@ size_t GetFileSize(const std::string& filename, int* error) {
return result;
}

bool EndsWith(const std::string& str, std::string_view suffix) {
size_t suffix_len = suffix.length();
size_t str_len = str.length();
if (str_len < suffix_len) {
return false;
}
return str.compare(str_len - suffix_len, suffix_len, suffix) == 0;
}

bool StartsWith(const std::string& str, std::string_view prefix) {
size_t prefix_len = prefix.length();
size_t str_len = str.length();
if (str_len < prefix_len) {
return false;
}
return str.compare(0, prefix_len, prefix) == 0;
}

bool FilenameIsConfigGypi(const std::string& path) {
return path == "config.gypi" || EndsWith(path, "/config.gypi");
constexpr bool FilenameIsConfigGypi(const std::string_view path) {
return path == "config.gypi" || path.ends_with("/config.gypi");
}

typedef std::vector<std::string> FileList;
typedef std::map<std::string, FileList> FileMap;

bool SearchFiles(const std::string& dir,
FileMap* file_map,
const std::string& extension) {
std::string_view extension) {
uv_fs_t scan_req;
int result = uv_fs_scandir(nullptr, &scan_req, dir.c_str(), 0, nullptr);
bool errored = false;
if (result < 0) {
PrintUvError("scandir", dir.c_str(), result);
errored = true;
} else {
auto it = file_map->insert({extension, FileList()}).first;
auto it = file_map->insert({std::string(extension), FileList()}).first;
FileList& files = it->second;
files.reserve(files.size() + result);
uv_dirent_t dent;
Expand All @@ -124,7 +104,7 @@ bool SearchFiles(const std::string& dir,
}

std::string path = dir + '/' + dent.name;
if (EndsWith(path, extension)) {
if (path.ends_with(extension)) {
files.emplace_back(path);
continue;
}
Expand Down Expand Up @@ -153,12 +133,11 @@ constexpr std::string_view kJsSuffix = ".js";
constexpr std::string_view kGypiSuffix = ".gypi";
constexpr std::string_view depsPrefix = "deps/";
constexpr std::string_view libPrefix = "lib/";
std::set<std::string_view> kAllowedExtensions{
kGypiSuffix, kJsSuffix, kMjsSuffix};

std::string_view HasAllowedExtensions(const std::string& filename) {
for (const auto& ext : kAllowedExtensions) {
if (EndsWith(filename, ext)) {
constexpr std::string_view HasAllowedExtensions(
const std::string_view filename) {
for (const auto& ext : {kGypiSuffix, kJsSuffix, kMjsSuffix}) {
if (filename.ends_with(ext)) {
return ext;
}
}
Expand Down Expand Up @@ -350,17 +329,17 @@ std::string GetFileId(const std::string& filename) {
size_t start = 0;
std::string prefix;
// Strip .mjs and .js suffix
if (EndsWith(filename, kMjsSuffix)) {
if (filename.ends_with(kMjsSuffix)) {
end -= kMjsSuffix.size();
} else if (EndsWith(filename, kJsSuffix)) {
} else if (filename.ends_with(kJsSuffix)) {
end -= kJsSuffix.size();
}

// deps/acorn/acorn/dist/acorn.js -> internal/deps/acorn/acorn/dist/acorn
if (StartsWith(filename, depsPrefix)) {
if (filename.starts_with(depsPrefix)) {
start = depsPrefix.size();
prefix = "internal/deps/";
} else if (StartsWith(filename, libPrefix)) {
} else if (filename.starts_with(libPrefix)) {
// lib/internal/url.js -> internal/url
start = libPrefix.size();
prefix = "";
Expand All @@ -381,18 +360,52 @@ std::string GetVariableName(const std::string& id) {
return result;
}

std::vector<std::string> GetCodeTable() {
size_t size = 1 << 16;
std::vector<std::string> code_table(size);
for (size_t i = 0; i < size; ++i) {
code_table[i] = std::to_string(i) + ',';
// The function returns a string buffer and an array of
// offsets. The string is just "0,1,2,3,...,65535,".
// The second array contain the offsets indicating the
// start of each substring ("0,", "1,", etc.) and the final
// offset points just beyond the end of the string.
// 382106 is the length of the string "0,1,2,3,...,65535,".
// 65537 is 2**16 + 1
// This function could be constexpr, but it might become too expensive to
// compile.
std::pair<std::array<char, 382106>, std::array<uint32_t, 65537>>
precompute_string() {
// the string "0,1,2,3,...,65535,".
std::array<char, 382106> str;
// the offsets in the string pointing at the beginning of each substring
std::array<uint32_t, 65537> off;
off[0] = 0;
char* p = &str[0];
constexpr auto const_int_to_str = [](uint16_t value, char* s) -> uint32_t {
uint32_t index = 0;
do {
s[index++] = '0' + (value % 10);
value /= 10;
} while (value != 0);

for (uint32_t i = 0; i < index / 2; ++i) {
char temp = s[i];
s[i] = s[index - i - 1];
s[index - i - 1] = temp;
}
s[index] = ',';
return index + 1;
};
for (int i = 0; i < 65536; ++i) {
size_t offset = const_int_to_str(i, p);
p += offset;
off[i + 1] = off[i] + offset;
}
return code_table;
return {str, off};
}

const std::string& GetCode(uint16_t index) {
static std::vector<std::string> table = GetCodeTable();
return table[index];
const std::string_view GetCode(uint16_t index) {
// We use about 644254 bytes of memory. An array of 65536 strings might use
// 2097152 bytes so we save 3x the memory.
static auto [backing_string, offsets] = precompute_string();
return std::string_view(&backing_string[offsets[index]],
offsets[index + 1] - offsets[index]);
}

#ifdef NODE_JS2C_USE_STRING_LITERALS
Expand Down Expand Up @@ -532,8 +545,7 @@ Fragment GetDefinitionImpl(const std::vector<char>& code,
// Avoid using snprintf on large chunks of data because it's much slower.
// It's fine to use it on small amount of data though.
if constexpr (is_two_byte) {
std::vector<uint16_t> utf16_codepoints;
utf16_codepoints.resize(count);
std::vector<uint16_t> utf16_codepoints(count);
size_t utf16_count = simdutf::convert_utf8_to_utf16(
code.data(),
code.size(),
Expand All @@ -542,8 +554,8 @@ Fragment GetDefinitionImpl(const std::vector<char>& code,
utf16_codepoints.resize(utf16_count);
Debug("static size %zu\n", utf16_count);
for (size_t i = 0; i < utf16_count; ++i) {
const std::string& str = GetCode(utf16_codepoints[i]);
memcpy(result.data() + cur, str.c_str(), str.size());
std::string_view str = GetCode(utf16_codepoints[i]);
memcpy(result.data() + cur, str.data(), str.size());
cur += str.size();
}
} else {
Expand All @@ -556,8 +568,8 @@ Fragment GetDefinitionImpl(const std::vector<char>& code,
i,
ch);
}
const std::string& str = GetCode(ch);
memcpy(result.data() + cur, str.c_str(), str.size());
std::string_view str = GetCode(ch);
memcpy(result.data() + cur, str.data(), str.size());
cur += str.size();
}
}
Expand Down Expand Up @@ -895,8 +907,8 @@ int Main(int argc, char* argv[]) {
int error = 0;
const std::string& file = args[i];
if (IsDirectory(file, &error)) {
if (!SearchFiles(file, &file_map, std::string(kJsSuffix)) ||
!SearchFiles(file, &file_map, std::string(kMjsSuffix))) {
if (!SearchFiles(file, &file_map, kJsSuffix) ||
!SearchFiles(file, &file_map, kMjsSuffix)) {
return 1;
}
} else if (error != 0) {
Expand Down

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