RESTinio
try_parse_field.hpp
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1 /*
2  * RESTinio
3  */
4 
12 #pragma once
13 
15 
18 #include <restinio/variant.hpp>
19 
20 #include <iostream>
21 
22 namespace restinio
23 {
24 
25 namespace http_field_parsers
26 {
27 
28 //
29 // field_not_found_t
30 //
38 
39 namespace try_extract_field_details
40 {
41 
42 //
43 // result_variant_t
44 //
51 template< typename Parsed_Field_Type >
53  Parsed_Field_Type,
56 
57 //
58 // valid_field_type
59 //
60 template< typename, typename = restinio::utils::metaprogramming::void_t<> >
61 struct valid_field_type : public std::false_type {};
62 
63 template< typename T >
65  T,
67  std::enable_if_t<
68  std::is_same<
69  expected_t< T, restinio::easy_parser::parse_error_t >,
70  decltype(T::try_parse(std::declval<string_view_t>()))
71  >::value,
72  bool
73  >
74  >
75  > : public std::true_type
76 {};
77 
78 //
79 // try_extract_field_value_from
80 //
81 template< typename Parsed_Field_Type >
86  string_view_t default_value )
87 {
89  "Parsed_Field_Type should have static try_parse method that "
90  "accepts string_view_t and returns "
91  "expected_t<Parsed_Field_Type, parse_error_t>" );
92 
93  if( !opt_value && default_value.empty() )
94  return { field_not_found_t{} };
95 
96  string_view_t content = opt_value ? *opt_value : default_value;
97 
98  auto parse_result = Parsed_Field_Type::try_parse( content );
99  if( parse_result )
100  return { std::move(*parse_result) };
101  else
102  return { parse_result.error() };
103 }
104 
105 } /* namespace try_extract_field_details */
106 
107 //
108 // try_parse_field
109 //
144 template< typename Parsed_Field_Type >
146 auto
149  const request_t & req,
151  string_view_t field_name,
155  string_view_t default_value = string_view_t{} )
156 {
157  using namespace try_extract_field_details;
158 
159  return try_extract_field_value_from< Parsed_Field_Type >(
160  req.header().opt_value_of( field_name ),
161  default_value );
162 }
163 
198 template< typename Parsed_Field_Type >
200 auto
203  const request_t & req,
205  http_field_t field_id,
209  string_view_t default_value = string_view_t{} )
210 {
211  using namespace try_extract_field_details;
212 
213  return try_extract_field_value_from< Parsed_Field_Type >(
214  req.header().opt_value_of( field_id ),
215  default_value );
216 }
217 
218 } /* namespace http_field_parsers */
219 
220 } /* namespace restinio */
221 
RESTINIO_NODISCARD
#define RESTINIO_NODISCARD
Definition: compiler_features.hpp:33
nonstd::optional_lite::std11::move
T & move(T &t)
Definition: optional.hpp:421
request_handler.hpp
restinio::easy_parser::parse_error_t
Information about parsing error.
Definition: easy_parser.hpp:93
restinio::http_field_parsers::try_extract_field_details::try_extract_field_value_from
RESTINIO_NODISCARD result_variant_t< Parsed_Field_Type > try_extract_field_value_from(optional_t< string_view_t > opt_value, string_view_t default_value)
Definition: try_parse_field.hpp:84
restinio::string_view_t
nonstd::string_view string_view_t
Definition: string_view.hpp:19
restinio::opt_value
std::enable_if< std::is_same< Parameter_Container, query_string_params_t >::value||std::is_same< Parameter_Container, router::route_params_t >::value, optional_t< Value_Type > >::type opt_value(const Parameter_Container &params, string_view_t key)
Gets the value of a parameter specified by key wrapped in optional_t<Value_Type> if parameter exists ...
Definition: value_or.hpp:64
restinio::http_field_parsers::try_extract_field_details::valid_field_type
Definition: try_parse_field.hpp:61
restinio::http_field_t
http_field_t
C++ enum that repeats nodejs c-style enum.
Definition: http_headers.hpp:233
easy_parser.hpp
An very small, simple and somewhat limited implementation of recursive-descent parser.
restinio::easy_parser::try_parse
RESTINIO_NODISCARD expected_t< typename Producer::result_type, parse_error_t > try_parse(string_view_t from, Producer producer)
Perform the parsing of the specified content by using specified value producer.
Definition: easy_parser.hpp:5042
nonstd::optional_lite::optional
class optional
Definition: optional.hpp:839
restinio::http_field_parsers::try_parse_field
RESTINIO_NODISCARD auto try_parse_field(const request_t &req, string_view_t field_name, string_view_t default_value=string_view_t{})
A helper function for extraction and parsing a value of HTTP-field.
Definition: try_parse_field.hpp:147
restinio::utils::metaprogramming::void_t
typename make_void< Ts... >::type void_t
Definition: metaprogramming.hpp:28
restinio::request_t::header
const http_request_header_t & header() const noexcept
Get request header.
Definition: request_handler.hpp:92
restinio::http_field_parsers::field_not_found_t
A special type to be returned in the case if HTTP-field isn't found in a request.
Definition: try_parse_field.hpp:37
restinio::http_header_fields_t::opt_value_of
optional_t< string_view_t > opt_value_of(string_view_t name) const noexcept
Get optional value of a field.
Definition: http_headers.hpp:1300
restinio
Definition: asio_include.hpp:21
variant.hpp
nonstd::variants::variant
Definition: variant.hpp:1209
http_headers.hpp
restinio::request_t
HTTP Request data.
Definition: request_handler.hpp:44