toml11/toml/serializer.hpp
2021-06-27 18:57:20 +09:00

923 lines
31 KiB
C++

// Copyright Toru Niina 2019.
// Distributed under the MIT License.
#ifndef TOML11_SERIALIZER_HPP
#define TOML11_SERIALIZER_HPP
#include <cmath>
#include <cstdio>
#include <limits>
#include "lexer.hpp"
#include "value.hpp"
namespace toml
{
// This function serialize a key. It checks a string is a bare key and
// escapes special characters if the string is not compatible to a bare key.
// ```cpp
// std::string k("non.bare.key"); // the key itself includes `.`s.
// std::string formatted = toml::format_key(k);
// assert(formatted == "\"non.bare.key\"");
// ```
//
// This function is exposed to make it easy to write a user-defined serializer.
// Since toml restricts characters available in a bare key, generally a string
// should be escaped. But checking whether a string needs to be surrounded by
// a `"` and escaping some special character is boring.
template<typename charT, typename traits, typename Alloc>
std::basic_string<charT, traits, Alloc>
format_key(const std::basic_string<charT, traits, Alloc>& k)
{
if(k.empty())
{
return std::string("\"\"");
}
// check the key can be a bare (unquoted) key
detail::location loc(k, std::vector<char>(k.begin(), k.end()));
detail::lex_unquoted_key::invoke(loc);
if(loc.iter() == loc.end())
{
return k; // all the tokens are consumed. the key is unquoted-key.
}
//if it includes special characters, then format it in a "quoted" key.
std::basic_string<charT, traits, Alloc> serialized("\"");
for(const char c : k)
{
switch(c)
{
case '\\': {serialized += "\\\\"; break;}
case '\"': {serialized += "\\\""; break;}
case '\b': {serialized += "\\b"; break;}
case '\t': {serialized += "\\t"; break;}
case '\f': {serialized += "\\f"; break;}
case '\n': {serialized += "\\n"; break;}
case '\r': {serialized += "\\r"; break;}
default : {serialized += c; break;}
}
}
serialized += "\"";
return serialized;
}
template<typename charT, typename traits, typename Alloc>
std::basic_string<charT, traits, Alloc>
format_keys(const std::vector<std::basic_string<charT, traits, Alloc>>& keys)
{
if(keys.empty())
{
return std::string("\"\"");
}
std::basic_string<charT, traits, Alloc> serialized;
for(const auto& ky : keys)
{
serialized += format_key(ky);
serialized += charT('.');
}
serialized.pop_back(); // remove the last dot '.'
return serialized;
}
template<typename Value>
struct serializer
{
static_assert(detail::is_basic_value<Value>::value,
"toml::serializer is for toml::value and its variants, "
"toml::basic_value<...>.");
using value_type = Value;
using key_type = typename value_type::key_type ;
using comment_type = typename value_type::comment_type ;
using boolean_type = typename value_type::boolean_type ;
using integer_type = typename value_type::integer_type ;
using floating_type = typename value_type::floating_type ;
using string_type = typename value_type::string_type ;
using local_time_type = typename value_type::local_time_type ;
using local_date_type = typename value_type::local_date_type ;
using local_datetime_type = typename value_type::local_datetime_type ;
using offset_datetime_type = typename value_type::offset_datetime_type;
using array_type = typename value_type::array_type ;
using table_type = typename value_type::table_type ;
serializer(const std::size_t w = 80u,
const int float_prec = std::numeric_limits<toml::floating>::max_digits10,
const bool can_be_inlined = false,
const bool no_comment = false,
std::vector<toml::key> ks = {},
const bool value_has_comment = false)
: can_be_inlined_(can_be_inlined), no_comment_(no_comment),
value_has_comment_(value_has_comment && !no_comment),
float_prec_(float_prec), width_(w), keys_(std::move(ks))
{}
~serializer() = default;
std::string operator()(const boolean_type& b) const
{
return b ? "true" : "false";
}
std::string operator()(const integer_type i) const
{
return std::to_string(i);
}
std::string operator()(const floating_type f) const
{
if(std::isnan(f))
{
if(std::signbit(f))
{
return std::string("-nan");
}
else
{
return std::string("nan");
}
}
else if(!std::isfinite(f))
{
if(std::signbit(f))
{
return std::string("-inf");
}
else
{
return std::string("inf");
}
}
const auto fmt = "%.*g";
const auto bsz = std::snprintf(nullptr, 0, fmt, this->float_prec_, f);
// +1 for null character(\0)
std::vector<char> buf(static_cast<std::size_t>(bsz + 1), '\0');
std::snprintf(buf.data(), buf.size(), fmt, this->float_prec_, f);
std::string token(buf.begin(), std::prev(buf.end()));
if(!token.empty() && token.back() == '.') // 1. => 1.0
{
token += '0';
}
const auto e = std::find_if(
token.cbegin(), token.cend(), [](const char c) noexcept -> bool {
return c == 'e' || c == 'E';
});
const auto has_exponent = (token.cend() != e);
const auto has_fraction = (token.cend() != std::find(
token.cbegin(), token.cend(), '.'));
if(!has_exponent && !has_fraction)
{
// the resulting value does not have any float specific part!
token += ".0";
}
return token;
}
std::string operator()(const string_type& s) const
{
if(s.kind == string_t::basic)
{
if((std::find(s.str.cbegin(), s.str.cend(), '\n') != s.str.cend() ||
std::find(s.str.cbegin(), s.str.cend(), '\"') != s.str.cend()) &&
this->width_ != std::numeric_limits<std::size_t>::max())
{
// if linefeed or double-quote is contained,
// make it multiline basic string.
const auto escaped = this->escape_ml_basic_string(s.str);
std::string open("\"\"\"");
std::string close("\"\"\"");
if(escaped.find('\n') != std::string::npos ||
this->width_ < escaped.size() + 6)
{
// if the string body contains newline or is enough long,
// add newlines after and before delimiters.
open += "\n";
close = std::string("\\\n") + close;
}
return open + escaped + close;
}
// no linefeed. try to make it oneline-string.
std::string oneline = this->escape_basic_string(s.str);
if(oneline.size() + 2 < width_ || width_ < 2)
{
const std::string quote("\"");
return quote + oneline + quote;
}
// the line is too long compared to the specified width.
// split it into multiple lines.
std::string token("\"\"\"\n");
while(!oneline.empty())
{
if(oneline.size() < width_)
{
token += oneline;
oneline.clear();
}
else if(oneline.at(width_-2) == '\\')
{
token += oneline.substr(0, width_-2);
token += "\\\n";
oneline.erase(0, width_-2);
}
else
{
token += oneline.substr(0, width_-1);
token += "\\\n";
oneline.erase(0, width_-1);
}
}
return token + std::string("\\\n\"\"\"");
}
else // the string `s` is literal-string.
{
if(std::find(s.str.cbegin(), s.str.cend(), '\n') != s.str.cend() ||
std::find(s.str.cbegin(), s.str.cend(), '\'') != s.str.cend() )
{
std::string open("'''");
if(this->width_ + 6 < s.str.size())
{
open += '\n'; // the first newline is ignored by TOML spec
}
const std::string close("'''");
return open + s.str + close;
}
else
{
const std::string quote("'");
return quote + s.str + quote;
}
}
}
std::string operator()(const local_date_type& d) const
{
std::ostringstream oss;
oss << d;
return oss.str();
}
std::string operator()(const local_time_type& t) const
{
std::ostringstream oss;
oss << t;
return oss.str();
}
std::string operator()(const local_datetime_type& dt) const
{
std::ostringstream oss;
oss << dt;
return oss.str();
}
std::string operator()(const offset_datetime_type& odt) const
{
std::ostringstream oss;
oss << odt;
return oss.str();
}
std::string operator()(const array_type& v) const
{
if(v.empty())
{
return std::string("[]");
}
if(this->is_array_of_tables(v))
{
return make_array_of_tables(v);
}
// not an array of tables. normal array.
// first, try to make it inline if none of the elements have a comment.
if( ! this->has_comment_inside(v))
{
const auto inl = this->make_inline_array(v);
if(inl.size() < this->width_ &&
std::find(inl.cbegin(), inl.cend(), '\n') == inl.cend())
{
return inl;
}
}
// if the length exceeds this->width_, print multiline array.
// key = [
// # ...
// 42,
// ...
// ]
std::string token;
std::string current_line;
token += "[\n";
for(const auto& item : v)
{
if( ! item.comments().empty() && !no_comment_)
{
// if comment exists, the element must be the only element in the line.
// e.g. the following is not allowed.
// ```toml
// array = [
// # comment for what?
// 1, 2, 3, 4, 5
// ]
// ```
if(!current_line.empty())
{
if(current_line.back() != '\n')
{
current_line += '\n';
}
token += current_line;
current_line.clear();
}
for(const auto& c : item.comments())
{
token += '#';
token += c;
token += '\n';
}
token += toml::visit(*this, item);
if(!token.empty() && token.back() == '\n') {token.pop_back();}
token += ",\n";
continue;
}
std::string next_elem;
if(item.is_table())
{
serializer ser(*this);
ser.can_be_inlined_ = true;
ser.width_ = std::numeric_limits<std::size_t>::max();
next_elem += toml::visit(ser, item);
}
else
{
next_elem += toml::visit(*this, item);
}
// comma before newline.
if(!next_elem.empty() && next_elem.back() == '\n') {next_elem.pop_back();}
// if current line does not exceeds the width limit, continue.
if(current_line.size() + next_elem.size() + 1 < this->width_)
{
current_line += next_elem;
current_line += ',';
}
else if(current_line.empty())
{
// if current line was empty, force put the next_elem because
// next_elem is not splittable
token += next_elem;
token += ",\n";
// current_line is kept empty
}
else // reset current_line
{
assert(current_line.back() == ',');
token += current_line;
token += '\n';
current_line = next_elem;
current_line += ',';
}
}
if(!current_line.empty())
{
if(!current_line.empty() && current_line.back() != '\n')
{
current_line += '\n';
}
token += current_line;
}
token += "]\n";
return token;
}
// templatize for any table-like container
std::string operator()(const table_type& v) const
{
// if an element has a comment, then it can't be inlined.
// table = {# how can we write a comment for this? key = "value"}
if(this->can_be_inlined_ && !(this->has_comment_inside(v)))
{
std::string token;
if(!this->keys_.empty())
{
token += format_key(this->keys_.back());
token += " = ";
}
token += this->make_inline_table(v);
if(token.size() < this->width_ &&
token.end() == std::find(token.begin(), token.end(), '\n'))
{
return token;
}
}
std::string token;
if(!keys_.empty())
{
token += '[';
token += format_keys(keys_);
token += "]\n";
}
token += this->make_multiline_table(v);
return token;
}
private:
std::string escape_basic_string(const std::string& s) const
{
//XXX assuming `s` is a valid utf-8 sequence.
std::string retval;
for(const char c : s)
{
switch(c)
{
case '\\': {retval += "\\\\"; break;}
case '\"': {retval += "\\\""; break;}
case '\b': {retval += "\\b"; break;}
case '\t': {retval += "\\t"; break;}
case '\f': {retval += "\\f"; break;}
case '\n': {retval += "\\n"; break;}
case '\r': {retval += "\\r"; break;}
default :
{
if((0x00 <= c && c <= 0x08) || (0x0A <= c && c <= 0x1F) || c == 0x7F)
{
retval += "\\u00";
retval += char(48 + (c / 16));
retval += char((c % 16 < 10 ? 48 : 55) + (c % 16));
}
else
{
retval += c;
}
}
}
}
return retval;
}
std::string escape_ml_basic_string(const std::string& s) const
{
std::string retval;
for(auto i=s.cbegin(), e=s.cend(); i!=e; ++i)
{
switch(*i)
{
case '\\': {retval += "\\\\"; break;}
// One or two consecutive "s are allowed.
// Later we will check there are no three consecutive "s.
// case '\"': {retval += "\\\""; break;}
case '\b': {retval += "\\b"; break;}
case '\t': {retval += "\\t"; break;}
case '\f': {retval += "\\f"; break;}
case '\n': {retval += "\n"; break;}
case '\r':
{
if(std::next(i) != e && *std::next(i) == '\n')
{
retval += "\r\n";
++i;
}
else
{
retval += "\\r";
}
break;
}
default :
{
const auto c = *i;
if((0x00 <= c && c <= 0x08) || (0x0A <= c && c <= 0x1F) || c == 0x7F)
{
retval += "\\u00";
retval += char(48 + (c / 16));
retval += char((c % 16 < 10 ? 48 : 55) + (c % 16));
}
else
{
retval += c;
}
}
}
}
// Only 1 or 2 consecutive `"`s are allowed in multiline basic string.
// 3 consecutive `"`s are considered as a closing delimiter.
// We need to check if there are 3 or more consecutive `"`s and insert
// backslash to break them down into several short `"`s like the `str6`
// in the following example.
// ```toml
// str4 = """Here are two quotation marks: "". Simple enough."""
// # str5 = """Here are three quotation marks: """.""" # INVALID
// str5 = """Here are three quotation marks: ""\"."""
// str6 = """Here are fifteen quotation marks: ""\"""\"""\"""\"""\"."""
// ```
auto found_3_quotes = retval.find("\"\"\"");
while(found_3_quotes != std::string::npos)
{
retval.replace(found_3_quotes, 3, "\"\"\\\"");
found_3_quotes = retval.find("\"\"\"");
}
return retval;
}
// if an element of a table or an array has a comment, it cannot be inlined.
bool has_comment_inside(const array_type& a) const noexcept
{
// if no_comment is set, comments would not be written.
if(this->no_comment_) {return false;}
for(const auto& v : a)
{
if(!v.comments().empty()) {return true;}
}
return false;
}
bool has_comment_inside(const table_type& t) const noexcept
{
// if no_comment is set, comments would not be written.
if(this->no_comment_) {return false;}
for(const auto& kv : t)
{
if(!kv.second.comments().empty()) {return true;}
}
return false;
}
std::string make_inline_array(const array_type& v) const
{
assert(!has_comment_inside(v));
std::string token;
token += '[';
bool is_first = true;
for(const auto& item : v)
{
if(is_first) {is_first = false;} else {token += ',';}
token += visit(serializer(
(std::numeric_limits<std::size_t>::max)(), this->float_prec_,
/* inlined */ true, /*no comment*/ false, /*keys*/ {},
/*has_comment*/ !item.comments().empty()), item);
}
token += ']';
return token;
}
std::string make_inline_table(const table_type& v) const
{
assert(!has_comment_inside(v));
assert(this->can_be_inlined_);
std::string token;
token += '{';
bool is_first = true;
for(const auto& kv : v)
{
// in inline tables, trailing comma is not allowed (toml-lang #569).
if(is_first) {is_first = false;} else {token += ',';}
token += format_key(kv.first);
token += '=';
token += visit(serializer(
(std::numeric_limits<std::size_t>::max)(), this->float_prec_,
/* inlined */ true, /*no comment*/ false, /*keys*/ {},
/*has_comment*/ !kv.second.comments().empty()), kv.second);
}
token += '}';
return token;
}
std::string make_multiline_table(const table_type& v) const
{
std::string token;
// print non-table elements first.
// ```toml
// [foo] # a table we're writing now here
// key = "value" # <- non-table element, "key"
// # ...
// [foo.bar] # <- table element, "bar"
// ```
// because after printing [foo.bar], the remaining non-table values will
// be assigned into [foo.bar], not [foo]. Those values should be printed
// earlier.
for(const auto& kv : v)
{
if(kv.second.is_table() || is_array_of_tables(kv.second))
{
continue;
}
token += write_comments(kv.second);
const auto key_and_sep = format_key(kv.first) + " = ";
const auto residual_width = (this->width_ > key_and_sep.size()) ?
this->width_ - key_and_sep.size() : 0;
token += key_and_sep;
token += visit(serializer(residual_width, this->float_prec_,
/*can be inlined*/ true, /*no comment*/ false, /*keys*/ {},
/*has_comment*/ !kv.second.comments().empty()), kv.second);
if(token.back() != '\n')
{
token += '\n';
}
}
// normal tables / array of tables
// after multiline table appeared, the other tables cannot be inline
// because the table would be assigned into the table.
// [foo]
// ...
// bar = {...} # <- bar will be a member of [foo].
bool multiline_table_printed = false;
for(const auto& kv : v)
{
if(!kv.second.is_table() && !is_array_of_tables(kv.second))
{
continue; // other stuff are already serialized. skip them.
}
std::vector<toml::key> ks(this->keys_);
ks.push_back(kv.first);
auto tmp = visit(serializer(this->width_, this->float_prec_,
!multiline_table_printed, this->no_comment_, ks,
/*has_comment*/ !kv.second.comments().empty()), kv.second);
// If it is the first time to print a multi-line table, it would be
// helpful to separate normal key-value pair and subtables by a
// newline.
// (this checks if the current key-value pair contains newlines.
// but it is not perfect because multi-line string can also contain
// a newline. in such a case, an empty line will be written) TODO
if((!multiline_table_printed) &&
std::find(tmp.cbegin(), tmp.cend(), '\n') != tmp.cend())
{
multiline_table_printed = true;
token += '\n'; // separate key-value pairs and subtables
token += write_comments(kv.second);
token += tmp;
// care about recursive tables (all tables in each level prints
// newline and there will be a full of newlines)
if(tmp.substr(tmp.size() - 2, 2) != "\n\n" &&
tmp.substr(tmp.size() - 4, 4) != "\r\n\r\n" )
{
token += '\n';
}
}
else
{
token += write_comments(kv.second);
token += tmp;
token += '\n';
}
}
return token;
}
std::string make_array_of_tables(const array_type& v) const
{
// if it's not inlined, we need to add `[[table.key]]`.
// but if it can be inlined, we can format it as the following.
// ```
// table.key = [
// {...},
// # comment
// {...},
// ]
// ```
// This function checks if inlinization is possible or not, and then
// format the array-of-tables in a proper way.
//
// Note about comments:
//
// If the array itself has a comment (value_has_comment_ == true), we
// should try to make it inline.
// ```toml
// # comment about array
// array = [
// # comment about table element
// {of = "table"}
// ]
// ```
// If it is formatted as a multiline table, the two comments becomes
// indistinguishable.
// ```toml
// # comment about array
// # comment about table element
// [[array]]
// of = "table"
// ```
// So we need to try to make it inline, and it force-inlines regardless
// of the line width limit.
// It may fail if the element of a table has comment. In that case,
// the array-of-tables will be formatted as a multiline table.
if(this->can_be_inlined_ || this->value_has_comment_)
{
std::string token;
if(!keys_.empty())
{
token += format_key(keys_.back());
token += " = ";
}
bool failed = false;
token += "[\n";
for(const auto& item : v)
{
// if an element of the table has a comment, the table
// cannot be inlined.
if(this->has_comment_inside(item.as_table()))
{
failed = true;
break;
}
// write comments for the table itself
token += write_comments(item);
const auto t = this->make_inline_table(item.as_table());
if(t.size() + 1 > width_ || // +1 for the last comma {...},
std::find(t.cbegin(), t.cend(), '\n') != t.cend())
{
// if the value itself has a comment, ignore the line width limit
if( ! this->value_has_comment_)
{
failed = true;
break;
}
}
token += t;
token += ",\n";
}
if( ! failed)
{
token += "]\n";
return token;
}
// if failed, serialize them as [[array.of.tables]].
}
std::string token;
for(const auto& item : v)
{
token += write_comments(item);
token += "[[";
token += format_keys(keys_);
token += "]]\n";
token += this->make_multiline_table(item.as_table());
}
return token;
}
std::string write_comments(const value_type& v) const
{
std::string retval;
if(this->no_comment_) {return retval;}
for(const auto& c : v.comments())
{
retval += '#';
retval += c;
retval += '\n';
}
return retval;
}
bool is_array_of_tables(const value_type& v) const
{
if(!v.is_array() || v.as_array().empty()) {return false;}
return is_array_of_tables(v.as_array());
}
bool is_array_of_tables(const array_type& v) const
{
// Since TOML v0.5.0, heterogeneous arrays are allowed. So we need to
// check all the element in an array to check if the array is an array
// of tables.
return std::all_of(v.begin(), v.end(), [](const value_type& elem) {
return elem.is_table();
});
}
private:
bool can_be_inlined_;
bool no_comment_;
bool value_has_comment_;
int float_prec_;
std::size_t width_;
std::vector<toml::key> keys_;
};
template<typename C,
template<typename ...> class M, template<typename ...> class V>
std::string
format(const basic_value<C, M, V>& v, std::size_t w = 80u,
int fprec = std::numeric_limits<toml::floating>::max_digits10,
bool no_comment = false, bool force_inline = false)
{
using value_type = basic_value<C, M, V>;
// if value is a table, it is considered to be a root object.
// the root object can't be an inline table.
if(v.is_table())
{
std::ostringstream oss;
if(!v.comments().empty())
{
oss << v.comments();
oss << '\n'; // to split the file comment from the first element
}
const auto serialized = visit(serializer<value_type>(w, fprec, no_comment, false), v);
oss << serialized;
return oss.str();
}
return visit(serializer<value_type>(w, fprec, force_inline), v);
}
namespace detail
{
template<typename charT, typename traits>
int comment_index(std::basic_ostream<charT, traits>&)
{
static const int index = std::ios_base::xalloc();
return index;
}
} // detail
template<typename charT, typename traits>
std::basic_ostream<charT, traits>&
nocomment(std::basic_ostream<charT, traits>& os)
{
// by default, it is zero. and by defalut, it shows comments.
os.iword(detail::comment_index(os)) = 1;
return os;
}
template<typename charT, typename traits>
std::basic_ostream<charT, traits>&
showcomment(std::basic_ostream<charT, traits>& os)
{
// by default, it is zero. and by defalut, it shows comments.
os.iword(detail::comment_index(os)) = 0;
return os;
}
template<typename charT, typename traits, typename C,
template<typename ...> class M, template<typename ...> class V>
std::basic_ostream<charT, traits>&
operator<<(std::basic_ostream<charT, traits>& os, const basic_value<C, M, V>& v)
{
using value_type = basic_value<C, M, V>;
// get status of std::setw().
const auto w = static_cast<std::size_t>(os.width());
const int fprec = static_cast<int>(os.precision());
os.width(0);
// by defualt, iword is initialized byl 0. And by default, toml11 outputs
// comments. So `0` means showcomment. 1 means nocommnet.
const bool no_comment = (1 == os.iword(detail::comment_index(os)));
if(!no_comment && v.is_table() && !v.comments().empty())
{
os << v.comments();
os << '\n'; // to split the file comment from the first element
}
// the root object can't be an inline table. so pass `false`.
const auto serialized = visit(serializer<value_type>(w, fprec, no_comment, false), v);
os << serialized;
// if v is a non-table value, and has only one comment, then
// put a comment just after a value. in the following way.
//
// ```toml
// key = "value" # comment.
// ```
//
// Since the top-level toml object is a table, one who want to put a
// non-table toml value must use this in a following way.
//
// ```cpp
// toml::value v;
// std::cout << "user-defined-key = " << v << std::endl;
// ```
//
// In this case, it is impossible to put comments before key-value pair.
// The only way to preserve comments is to put all of them after a value.
if(!no_comment && !v.is_table() && !v.comments().empty())
{
os << " #";
for(const auto& c : v.comments()) {os << c;}
}
return os;
}
} // toml
#endif// TOML11_SERIALIZER_HPP