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// Copyright 2017 Elias Kosunen
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// https://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
//
// This file is a part of scnlib:
// https://github.com/eliaskosunen/scnlib
#ifndef SCN_DETAIL_VISITOR_H
#define SCN_DETAIL_VISITOR_H
#include "../reader/reader.h"
namespace scn {
SCN_BEGIN_NAMESPACE
template <typename Context, typename ParseCtx>
class basic_visitor {
public:
using context_type = Context;
using char_type = typename Context::char_type;
using arg_type = basic_arg<char_type>;
basic_visitor(Context& ctx, ParseCtx& pctx)
: m_ctx(std::addressof(ctx)), m_pctx(std::addressof(pctx))
{
}
template <typename T>
auto operator()(T&& val) -> error
{
return visit(SCN_FWD(val), detail::priority_tag<1>{});
}
private:
auto visit(code_point& val, detail::priority_tag<1>) -> error
{
return detail::visitor_boilerplate<detail::code_point_scanner>(
val, *m_ctx, *m_pctx);
}
auto visit(span<char_type>& val, detail::priority_tag<1>) -> error
{
return detail::visitor_boilerplate<detail::span_scanner>(
val, *m_ctx, *m_pctx);
}
auto visit(bool& val, detail::priority_tag<1>) -> error
{
return detail::visitor_boilerplate<detail::bool_scanner>(
val, *m_ctx, *m_pctx);
}
#define SCN_VISIT_INT(T) \
error visit(T& val, detail::priority_tag<0>) \
{ \
return detail::visitor_boilerplate<detail::integer_scanner<T>>( \
val, *m_ctx, *m_pctx); \
}
SCN_VISIT_INT(signed char)
SCN_VISIT_INT(short)
SCN_VISIT_INT(int)
SCN_VISIT_INT(long)
SCN_VISIT_INT(long long)
SCN_VISIT_INT(unsigned char)
SCN_VISIT_INT(unsigned short)
SCN_VISIT_INT(unsigned int)
SCN_VISIT_INT(unsigned long)
SCN_VISIT_INT(unsigned long long)
SCN_VISIT_INT(char_type)
#undef SCN_VISIT_INT
#define SCN_VISIT_FLOAT(T) \
error visit(T& val, detail::priority_tag<1>) \
{ \
return detail::visitor_boilerplate<detail::float_scanner<T>>( \
val, *m_ctx, *m_pctx); \
}
SCN_VISIT_FLOAT(float)
SCN_VISIT_FLOAT(double)
SCN_VISIT_FLOAT(long double)
#undef SCN_VISIT_FLOAT
auto visit(std::basic_string<char_type>& val, detail::priority_tag<1>)
-> error
{
return detail::visitor_boilerplate<detail::string_scanner>(
val, *m_ctx, *m_pctx);
}
auto visit(basic_string_view<char_type>& val, detail::priority_tag<1>)
-> error
{
return detail::visitor_boilerplate<detail::string_view_scanner>(
val, *m_ctx, *m_pctx);
}
auto visit(typename arg_type::handle val, detail::priority_tag<1>)
-> error
{
return val.scan(*m_ctx, *m_pctx);
}
[[noreturn]] auto visit(detail::monostate, detail::priority_tag<0>)
-> error
{
SCN_UNREACHABLE;
}
Context* m_ctx;
ParseCtx* m_pctx;
};
template <typename Context, typename ParseCtx>
error visit(Context& ctx,
ParseCtx& pctx,
basic_args<typename Context::char_type> args)
{
using char_type = typename Context::char_type;
using arg_type = basic_arg<char_type>;
auto arg = arg_type{};
while (pctx) {
if (pctx.should_skip_ws()) {
// Skip whitespace from format string and from stream
// EOF is not an error
auto ret = skip_range_whitespace(ctx, false);
if (SCN_UNLIKELY(!ret)) {
if (ret == error::end_of_range) {
break;
}
SCN_CLANG_PUSH_IGNORE_UNDEFINED_TEMPLATE
auto rb = ctx.range().reset_to_rollback_point();
if (!rb) {
return rb;
}
return ret;
}
// Don't advance pctx, should_skip_ws() does it for us
continue;
}
// Non-brace character, or
// Brace followed by another brace, meaning a literal '{'
if (pctx.should_read_literal()) {
if (SCN_UNLIKELY(!pctx)) {
return {error::invalid_format_string,
"Unexpected end of format string"};
}
// Check for any non-specifier {foo} characters
alignas(typename Context::char_type) unsigned char buf[4] = {0};
auto ret = read_code_point(ctx.range(), make_span(buf, 4));
SCN_CLANG_POP_IGNORE_UNDEFINED_TEMPLATE
if (!ret || !pctx.check_literal(ret.value().chars)) {
auto rb = ctx.range().reset_to_rollback_point();
if (!rb) {
// Failed rollback
return rb;
}
if (!ret) {
// Failed read
return ret.error();
}
// Mismatching characters in scan string and stream
return {error::invalid_scanned_value,
"Expected character from format string not "
"found in the stream"};
}
// Bump pctx to next char
if (!pctx.advance_cp()) {
pctx.advance_char();
}
}
else {
// Scan argument
auto arg_wrapped = [&]() -> expected<arg_type> {
if (!pctx.has_arg_id()) {
return next_arg(args, pctx);
}
auto id_wrapped = pctx.parse_arg_id();
if (!id_wrapped) {
return id_wrapped.error();
}
auto id = id_wrapped.value();
SCN_ENSURE(!id.empty());
if (ctx.locale().get_static().is_digit(id.front())) {
auto s =
detail::simple_integer_scanner<std::ptrdiff_t>{};
std::ptrdiff_t i{0};
auto span = make_span(id.data(), id.size());
SCN_CLANG_PUSH_IGNORE_UNDEFINED_TEMPLATE
auto ret = s.scan(span, i, 10);
SCN_CLANG_POP_IGNORE_UNDEFINED_TEMPLATE
if (!ret || ret.value() != span.end()) {
return error(error::invalid_format_string,
"Failed to parse argument id from "
"format string");
}
return get_arg(args, pctx, i);
}
return get_arg(args, pctx, id);
}();
if (!arg_wrapped) {
return arg_wrapped.error();
}
arg = arg_wrapped.value();
SCN_ENSURE(arg);
if (!pctx) {
return {error::invalid_format_string,
"Unexpected end of format argument"};
}
auto ret = visit_arg<char_type>(
basic_visitor<Context, ParseCtx>(ctx, pctx), arg);
if (!ret) {
auto rb = ctx.range().reset_to_rollback_point();
if (!rb) {
return rb;
}
return ret;
}
// Handle next arg and bump pctx
pctx.arg_handled();
if (pctx) {
auto e = pctx.advance_cp();
if (!e) {
return e;
}
}
}
}
if (pctx) {
// Format string not exhausted
return {error::invalid_format_string,
"Format string not exhausted"};
}
ctx.range().set_rollback_point();
return {};
}
SCN_END_NAMESPACE
} // namespace scn
#endif // SCN_DETAIL_VISITOR_H
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