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daw_json_parse_string_quote.h
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1// Copyright (c) Darrell Wright
2//
3// Distributed under the Boost Software License, Version 1.0. (See accompanying
4// file LICENSE or copy at http://www.boost.org/LICENSE_1_0.txt)
5//
6// Official repository: https://github.com/beached/daw_json_link
7//
8
9#pragma once
10
11#include "daw/json/impl/version.h"
12
13#include "daw/json/impl/daw_json_assert.h"
14#include "daw/json/impl/daw_not_const_ex_functions.h"
15
16#include <daw/daw_traits.h>
17#include <daw/daw_uint_buffer.h>
18
19#include <cstddef>
20#include <type_traits>
21
22namespace daw::json {
23 inline namespace DAW_JSON_VER {
24 namespace json_details::string_quote {
25 template<std::size_t N, char c>
26 constexpr UInt8 test_at_byte( UInt64 b ) {
27 auto const lhs = b & ( 0xFF_u64 << ( N * 8U ) );
28 using rhs = daw::constant<to_uint64( static_cast<unsigned char>( c ) )
29 << ( N * 8U )>;
30 return to_uint8( not( lhs - rhs::value ) );
31 }
32
33 template<std::size_t N, char c>
34 DAW_ATTRIB_INLINE constexpr UInt8 test_at_byte( UInt32 b ) {
35 auto const lhs = b & ( 0xFF_u32 << ( N * 8U ) );
36 using rhs = daw::constant<to_uint32( static_cast<unsigned char>( c ) )
37 << ( N * 8U )>;
38 return to_uint8( not( lhs - rhs::value ) );
39 }
40
41 constexpr void skip_to_first8( daw::not_null<char const *> &first,
42 daw::not_null<char const *> const last ) {
43 bool keep_going = last - first >= 8;
44 while( keep_going ) {
45 auto buff = daw::to_uint64_buffer( first.get( ) );
46 auto const q7 = test_at_byte<7U, '"'>( buff );
47 auto const q6 = test_at_byte<6U, '"'>( buff );
48 auto const q5 = test_at_byte<5U, '"'>( buff );
49 auto const q4 = test_at_byte<4U, '"'>( buff );
50 auto const q3 = test_at_byte<3U, '"'>( buff );
51 auto const q2 = test_at_byte<2U, '"'>( buff );
52 auto const q1 = test_at_byte<1U, '"'>( buff );
53 auto const q0 = test_at_byte<0U, '"'>( buff );
54 auto const s7 = test_at_byte<7U, '\\'>( buff );
55 auto const s6 = test_at_byte<6U, '\\'>( buff );
56 auto const s5 = test_at_byte<5U, '\\'>( buff );
57 auto const s4 = test_at_byte<4U, '\\'>( buff );
58 auto const s3 = test_at_byte<3U, '\\'>( buff );
59 auto const s2 = test_at_byte<2U, '\\'>( buff );
60 auto const s1 = test_at_byte<1U, '\\'>( buff );
61 auto const s0 = test_at_byte<0U, '\\'>( buff );
62
63 keep_going = not( q0 | q1 | q2 | q3 | q4 | q5 | q6 | q7 | s0 | s1 |
64 s2 | s3 | s4 | s5 | s6 | s7 );
65 keep_going = keep_going & static_cast<bool>( last - first >= 16 );
66 first += static_cast<int>( keep_going ) * 8;
67 }
68 first -= *( first - 1 ) == '\\' ? 1 : 0;
69 }
70
71 constexpr void skip_to_first4( daw::not_null<char const *> &first,
72 daw::not_null<char const *> const last ) {
73 bool keep_going = last - first >= 4;
74 while( keep_going ) {
75 // Need to look for escapes as this is fast path
76 auto buff = daw::to_uint32_buffer( first.get( ) );
77 auto const q3 = test_at_byte<3U, '"'>( buff );
78 auto const q2 = test_at_byte<2U, '"'>( buff );
79 auto const q1 = test_at_byte<1U, '"'>( buff );
80 auto const q0 = test_at_byte<0U, '"'>( buff );
81 auto const s3 = test_at_byte<3U, '\\'>( buff );
82 auto const s2 = test_at_byte<2U, '\\'>( buff );
83 auto const s1 = test_at_byte<1U, '\\'>( buff );
84 auto const s0 = test_at_byte<0U, '\\'>( buff );
85 keep_going = not( q0 | q1 | q2 | q3 | s0 | s1 | s2 | s3 );
86 keep_going = keep_going & static_cast<bool>( last - first >= 8 );
87 first += static_cast<int>( keep_going ) * 4;
88 }
89 first -= *( first - 1 ) == '\\' ? 1 : 0;
90 }
91
92 namespace string_quote_parser {
93 template<typename ParseState>
94 [[nodiscard]] static constexpr std::size_t
95 parse_nq_uncheck( ParseState &parse_state ) {
96 std::ptrdiff_t need_slow_path = -1;
97 auto first =
98 daw::not_null<char const *>( daw::never_null, parse_state.first );
99 auto const last =
100 daw::not_null<char const *>( daw::never_null, parse_state.last );
101 // This is a logic error to happen.
102 // daw_json_assert_weak( first != '"', "Unexpected quote", parse_state
103 // );
104 if( json_details::use_constexpr_exec_mode<
105 typename ParseState::exec_tag_t>( ) ) {
106 first =
107 mem_skip_until_end_of_string<true,
108 typename ParseState::exec_tag_t>(
109 first, last, need_slow_path );
110 } else {
111 {
112 auto const sz = last - first;
113 if( sz >= 8 ) {
114 skip_to_first8( first, last );
115 } else if( sz >= 4 ) {
116 skip_to_first4( first, last );
117 }
118 }
119 while( *first != '"' ) {
120 while( []( char c ) DAW_JSON_CPP23_STATIC_CALL_OP {
121 return daw::nsc_and( c != '"', c != '\\' );
122 }( *first ) ) {
123 ++first;
124 }
125 if( *first == '\\' ) {
126 if( need_slow_path < 0 ) {
127 need_slow_path = first - parse_state.first;
128 }
129 first += 2;
130 } else {
131 break;
132 }
133 }
134 }
135 parse_state.first = first;
136 return static_cast<std::size_t>( need_slow_path );
137 }
138
139 template<typename ParseState>
140 [[nodiscard]] static constexpr std::size_t
141 parse_nq_check( ParseState &parse_state ) {
142
143 std::ptrdiff_t need_slow_path = -1;
144 auto first = daw::not_null<char const *>( parse_state.first );
145 auto const last =
146 daw::not_null<char const *>( parse_state.class_last );
147
148 if( not json_details::use_constexpr_exec_mode<
149 typename ParseState::exec_tag_t>( ) ) {
150 first =
151 mem_skip_until_end_of_string<false,
152 typename ParseState::exec_tag_t>(
153 first, last, need_slow_path );
154 } else {
155 if constexpr( not ParseState::exclude_special_escapes ) {
156 if( auto const l =
157 daw::not_null<char const *>( parse_state.last );
158 l - first >= 8 ) {
159 skip_to_first8( first, l );
160 } else if( last - first >= 4 ) {
161 skip_to_first4( first, l );
162 }
163 }
164 if constexpr( ParseState::is_zero_terminated_string ) {
165 if constexpr( ParseState::exclude_special_escapes ) {
166 while( *first != '\0' ) {
167 char c = *first;
168 daw_json_ensure( static_cast<unsigned char>( c ) >= 0x20U,
169 ErrorReason::InvalidString,
170 parse_state );
171 if( c == '\\' ) {
172 daw_json_ensure( last - first > 1,
173 ErrorReason::InvalidString,
174 parse_state );
175 if( need_slow_path < 0 ) {
176 need_slow_path = first - parse_state.first;
177 }
178 ++first;
179 c = *first;
180 switch( c ) {
181 case '"':
182 case '\\':
183 case '/':
184 case 'b':
185 case 'f':
186 case 'n':
187 case 'r':
188 case 't':
189 case 'u':
190 break;
191 default:
192 daw_json_error( ErrorReason::InvalidString, parse_state );
193 }
194 } else if( c == '"' ) {
195 break;
196 }
197 ++first;
198 }
199 } else {
200 while( daw::nsc_and( *first != 0, *first != '"' ) ) {
201 while( daw::nsc_and(
202 *first != 0, *first != '"', *first != '\\' ) ) {
203 ++first;
204 }
205
206 if( daw::nsc_and( *first != 0, *first == '\\' ) ) {
207 if( need_slow_path < 0 ) {
208 need_slow_path = first - parse_state.first;
209 }
210 first += 2;
211 } else {
212 break;
213 }
214 }
215 }
216 } else {
217 if constexpr( ParseState::exclude_special_escapes ) {
218 while( first < last ) {
219 char c = *first;
220 daw_json_ensure( static_cast<unsigned char>( c ) >= 0x20U,
221 ErrorReason::InvalidString,
222 parse_state );
223 if( c == '\\' ) {
224 daw_json_ensure( last - first > 1,
225 ErrorReason::InvalidString,
226 parse_state );
227 if( need_slow_path < 0 ) {
228 need_slow_path = first - parse_state.first;
229 }
230 ++first;
231 c = *first;
232 switch( c ) {
233 case '"':
234 case '\\':
235 case '/':
236 case 'b':
237 case 'f':
238 case 'n':
239 case 'r':
240 case 't':
241 case 'u':
242 break;
243 default:
244 daw_json_error( ErrorReason::InvalidString, parse_state );
245 }
246 } else if( c == '"' ) {
247 break;
248 }
249 ++first;
250 }
251 } else {
252 while( first < last and *first != '"' ) {
253 while( first < last and
254 daw::nsc_and( *first != '"', *first != '\\' ) ) {
255 ++first;
256 }
257
258 if( first < last and *first == '\\' ) {
259 if( need_slow_path < 0 ) {
260 need_slow_path = first - parse_state.first;
261 }
262 first += 2;
263 } else {
264 break;
265 }
266 }
267 }
268 }
269 }
270 if constexpr( ParseState::is_zero_terminated_string ) {
271 daw_json_assert_weak(
272 *first == '"', ErrorReason::InvalidString, parse_state );
273 } else {
274 daw_json_assert_weak( first < last and *first == '"',
275 ErrorReason::InvalidString,
276 parse_state );
277 }
278 parse_state.first = first;
279 return static_cast<std::size_t>( need_slow_path );
280 }
281
282 template<typename ParseState>
283 [[nodiscard]] DAW_ATTRIB_FLATTEN static constexpr std::size_t
284 parse_nq( ParseState &parse_state ) {
285 if constexpr( ParseState::is_unchecked_input ) {
286 return parse_nq_uncheck( parse_state );
287 } else {
288 return parse_nq_check( parse_state );
289 }
290 }
291 } // namespace string_quote_parser
292 } // namespace json_details::string_quote
293 } // namespace DAW_JSON_VER
294} // namespace daw::json
daw_json_assert.h
daw_json_assert_weak
#define daw_json_assert_weak(Bool,...)
Assert that Bool is true when in Checked Input mode If false pass rest of args to daw_json_error.
Definition daw_json_assert.h:163
daw_json_ensure
#define daw_json_ensure(Bool,...)
Ensure that Bool is true. If false pass rest of args to daw_json_error.
Definition daw_json_assert.h:154
DAW_JSON_CPP23_STATIC_CALL_OP
#define DAW_JSON_CPP23_STATIC_CALL_OP
Definition daw_json_switches.h:207
daw_not_const_ex_functions.h
daw::json::anonymous_namespace{daw_json_assert.h}::daw_json_error
DAW_ATTRIB_NOINLINE void daw_json_error(ErrorReason reason)
Definition daw_json_assert.h:77
daw::json
Customization point traits.
Definition daw_container_traits.h:24
DAW_JSON_VER
#define DAW_JSON_VER
The version string used in namespace definitions. Must be a valid namespace name.
Definition version.h:20
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