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1 /*
2  *
3  * Copyright 2015 gRPC authors.
4  *
5  * Licensed under the Apache License, Version 2.0 (the "License");
6  * you may not use this file except in compliance with the License.
7  * You may obtain a copy of the License at
8  *
9  *     http://www.apache.org/licenses/LICENSE-2.0
10  *
11  * Unless required by applicable law or agreed to in writing, software
12  * distributed under the License is distributed on an "AS IS" BASIS,
13  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
14  * See the License for the specific language governing permissions and
15  * limitations under the License.
16  *
17  */
18 
19 #ifndef GRPC_CORE_LIB_JSON_JSON_READER_H
20 #define GRPC_CORE_LIB_JSON_JSON_READER_H
21 
22 #include <grpc/support/port_platform.h>
23 
24 #include "src/core/lib/json/json_common.h"
25 
26 typedef enum {
27   GRPC_JSON_STATE_OBJECT_KEY_BEGIN,
28   GRPC_JSON_STATE_OBJECT_KEY_STRING,
29   GRPC_JSON_STATE_OBJECT_KEY_END,
30   GRPC_JSON_STATE_VALUE_BEGIN,
31   GRPC_JSON_STATE_VALUE_STRING,
32   GRPC_JSON_STATE_STRING_ESCAPE,
33   GRPC_JSON_STATE_STRING_ESCAPE_U1,
34   GRPC_JSON_STATE_STRING_ESCAPE_U2,
35   GRPC_JSON_STATE_STRING_ESCAPE_U3,
36   GRPC_JSON_STATE_STRING_ESCAPE_U4,
37   GRPC_JSON_STATE_VALUE_NUMBER,
38   GRPC_JSON_STATE_VALUE_NUMBER_WITH_DECIMAL,
39   GRPC_JSON_STATE_VALUE_NUMBER_ZERO,
40   GRPC_JSON_STATE_VALUE_NUMBER_DOT,
41   GRPC_JSON_STATE_VALUE_NUMBER_E,
42   GRPC_JSON_STATE_VALUE_NUMBER_EPM,
43   GRPC_JSON_STATE_VALUE_TRUE_R,
44   GRPC_JSON_STATE_VALUE_TRUE_U,
45   GRPC_JSON_STATE_VALUE_TRUE_E,
46   GRPC_JSON_STATE_VALUE_FALSE_A,
47   GRPC_JSON_STATE_VALUE_FALSE_L,
48   GRPC_JSON_STATE_VALUE_FALSE_S,
49   GRPC_JSON_STATE_VALUE_FALSE_E,
50   GRPC_JSON_STATE_VALUE_NULL_U,
51   GRPC_JSON_STATE_VALUE_NULL_L1,
52   GRPC_JSON_STATE_VALUE_NULL_L2,
53   GRPC_JSON_STATE_VALUE_END,
54   GRPC_JSON_STATE_END
55 } grpc_json_reader_state;
56 
57 enum {
58   /* The first non-unicode value is 0x110000. But let's pick
59    * a value high enough to start our error codes from. These
60    * values are safe to return from the read_char function.
61    */
62   GRPC_JSON_READ_CHAR_EOF = 0x7ffffff0,
63   GRPC_JSON_READ_CHAR_EAGAIN,
64   GRPC_JSON_READ_CHAR_ERROR
65 };
66 
67 struct grpc_json_reader;
68 
69 typedef struct grpc_json_reader_vtable {
70   /* Clears your internal string scratchpad. */
71   void (*string_clear)(void* userdata);
72   /* Adds a char to the string scratchpad. */
73   void (*string_add_char)(void* userdata, uint32_t c);
74   /* Adds a utf32 char to the string scratchpad. */
75   void (*string_add_utf32)(void* userdata, uint32_t c);
76   /* Reads a character from your input. May be utf-8, 16 or 32. */
77   uint32_t (*read_char)(void* userdata);
78   /* Starts a container of type GRPC_JSON_ARRAY or GRPC_JSON_OBJECT. */
79   void (*container_begins)(void* userdata, grpc_json_type type);
80   /* Ends the current container. Must return the type of its parent. */
81   grpc_json_type (*container_ends)(void* userdata);
82   /* Your internal string scratchpad is an object's key. */
83   void (*set_key)(void* userdata);
84   /* Your internal string scratchpad is a string value. */
85   void (*set_string)(void* userdata);
86   /* Your internal string scratchpad is a numerical value. Return 1 if valid. */
87   int (*set_number)(void* userdata);
88   /* Sets the values true, false or null. */
89   void (*set_true)(void* userdata);
90   void (*set_false)(void* userdata);
91   void (*set_null)(void* userdata);
92 } grpc_json_reader_vtable;
93 
94 typedef struct grpc_json_reader {
95   /* That structure is fully private, and initialized by grpc_json_reader_init.
96    * The definition is public so you can put it on your stack.
97    */
98 
99   void* userdata;
100   grpc_json_reader_vtable* vtable;
101   int depth;
102   int in_object;
103   int in_array;
104   int escaped_string_was_key;
105   int container_just_begun;
106   uint16_t unicode_char, unicode_high_surrogate;
107   grpc_json_reader_state state;
108 } grpc_json_reader;
109 
110 /* The return type of the parser. */
111 typedef enum {
112   GRPC_JSON_DONE,          /* The parser finished successfully. */
113   GRPC_JSON_EAGAIN,        /* The parser yields to get more data. */
114   GRPC_JSON_READ_ERROR,    /* The parser passes through a read error. */
115   GRPC_JSON_PARSE_ERROR,   /* The parser found an error in the json stream. */
116   GRPC_JSON_INTERNAL_ERROR /* The parser got an internal error. */
117 } grpc_json_reader_status;
118 
119 /* Call this function to start parsing the input. It will return the following:
120  *    . GRPC_JSON_DONE if the input got eof, and the parsing finished
121  *      successfully.
122  *    . GRPC_JSON_EAGAIN if the read_char function returned again. Call the
123  *      parser again as needed. It is okay to call the parser in polling mode,
124  *      although a bit dull.
125  *    . GRPC_JSON_READ_ERROR if the read_char function returned an error. The
126  *      state isn't broken however, and the function can be called again if the
127  *      error has been corrected. But please use the EAGAIN feature instead for
128  *      consistency.
129  *    . GRPC_JSON_PARSE_ERROR if the input was somehow invalid.
130  *    . GRPC_JSON_INTERNAL_ERROR if the parser somehow ended into an invalid
131  *      internal state.
132  */
133 grpc_json_reader_status grpc_json_reader_run(grpc_json_reader* reader);
134 
135 /* Call this function to initialize the reader structure. */
136 void grpc_json_reader_init(grpc_json_reader* reader,
137                            grpc_json_reader_vtable* vtable, void* userdata);
138 
139 /* You may call this from the read_char callback if you don't know where is the
140  * end of your input stream, and you'd like the json reader to hint you that it
141  * has completed reading its input, so you can return an EOF to it. Note that
142  * there might still be trailing whitespaces after that point.
143  */
144 int grpc_json_reader_is_complete(grpc_json_reader* reader);
145 
146 #endif /* GRPC_CORE_LIB_JSON_JSON_READER_H */
147