Telodendria/src/include/Json.h

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/*
* Copyright (C) 2022 Jordan Bancino <@jordan:bancino.net>
*
* Permission is hereby granted, free of charge, to any person
* obtaining a copy of this software and associated documentation files
* (the "Software"), to deal in the Software without restriction,
* including without limitation the rights to use, copy, modify, merge,
* publish, distribute, sublicense, and/or sell copies of the Software,
* and to permit persons to whom the Software is furnished to do so,
* subject to the following conditions:
*
* The above copyright notice and this permission notice shall be
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* included in all copies or portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
* EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
* MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
* NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
* BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
* ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
* CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
* SOFTWARE.
*/
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/*
* Json.h: A fully-featured JSON API for C using Arrays and HashMaps.
* This API builds on the foundations of Arrays and HashMaps, because
* that's all a JSON object really is. It provides a JsonValue, which
* is used to encapsulate arbitrary values while being able to identify
* them in the future, so that JSON can be effectively handled.
*
* This implementation is just to get the job done in parsing and
* generating JSON. It is extremely strict; it will fail on syntax
* errors. This is fine for Matrix, because we can just return
* M_BAD_JSON anything in here fails.
*
* One thing to note about this implementation is that it focuses
* primarily on serialization and deserialization to and from streams.
* What this means is that it does not provide facilities for handling
* JSON strings; it only writes JSON to output streams, and reading
* them from input streams. Of course, you could use the POSIX
* fmemopen() and open_memstream() functions if you really want to deal
* with JSON strings, but JSON is intended to be an exchange format.
* Data should be converted to JSON when it is leaving, and converted
* from JSON when it is coming in. Ideally, most of the program would
* have no idea what JSON actually is.
*/
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#ifndef TELODENDRIA_JSON_H
#define TELODENDRIA_JSON_H
#include <HashMap.h>
#include <Array.h>
#include <stdio.h>
#include <stddef.h>
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/*
* All the possible JSON types. This enumeration is used to identify
* the type of the value stored in a JsonValue.
*/
typedef enum JsonType
{
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JSON_NULL, /* Maps to nothing. */
JSON_OBJECT, /* Maps to a HashMap of JsonValues */
JSON_ARRAY, /* Maps to an Array of JsonValues */
JSON_STRING, /* Maps to a C string */
JSON_INTEGER, /* Maps to a C long */
JSON_FLOAT, /* Maps to a C double */
JSON_BOOLEAN /* Maps to a C 1 or 0 */
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} JsonType;
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/*
* A JsonValue encapsulates all the possible values that can be stored
* in a JSON object as a single type, so as to provide a consistent
* API for accessing and setting them. It is an opaque structure that
* can be managed entirely by the functions defined in this API.
*
* Note that in the case of objects, arrays, and strings, this structure
* only stores pointers to allocated data, it doesn't store the data
* itself. JsonValues only store integers, floats, booleans, and NULL
* in their memory. Anything else must be freed separately.
*/
typedef struct JsonValue JsonValue;
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/*
* Get the type of a JsonValue.
*
* Params:
*
* (JsonValue *) The value to get the type of.
*
* Return: A JsonType that tells what the provided value is, or
* JSON_NULL if the passed value is NULL. Note that even a fully
* valid JsonValue may still be of type JSON_NULL, so this function
* should not be used to check whether or not the JSON value is valid.
*/
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extern JsonType
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JsonValueType(JsonValue *);
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/*
* Wrap a HashMap into a JsonValue that represents a JSON object. Note
* that the HashMap should contain only JsonValues. Any other contents
* are not supported and will lead to undefined behavior.
*
* Params:
*
* (HashMap *) The hash map of JsonValues to wrap in a JsonValue.
*
* Return: A JsonValue that holds a pointer to the given object, or
* NULL if there was an error allocating memory.
*/
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extern JsonValue *
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JsonValueObject(HashMap *);
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/*
* Get a HashMap from a JsonValue that represents a JSON object.
*
* Params:
*
* (JsonValue *) The value to extract the object from.
*
* Return: A HashMap of JsonValues, or NULL if no value was provided,
* or the value is not of type JSON_OBJECT.
*/
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extern HashMap *
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JsonValueAsObject(JsonValue *);
/*
* The following methods very closely resemble the ones above, and
* behave pretty much the exact same. To save on time and effort,
* I'm choosing not to explicitly document all of these. If something
* is unclear about how these functions work, consult the source code,
* and then feel free to write the documentation yourself.
*
* Otherwise, reach out to the official Matrix room, and someone will
* be able to help you.
*/
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extern JsonValue *
JsonValueArray(Array * array);
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extern Array *
JsonValueAsArray(JsonValue * value);
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extern JsonValue *
JsonValueString(char *string);
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extern JsonValue *
JsonValueInteger(long integer);
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extern JsonValue *
JsonValueFloat(double floating);
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extern JsonValue *
JsonValueBoolean(int boolean);
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/*
* Create a JsonValue that represents a JSON null. Because Arrays and
* HashMaps should not contain NULL values, I thought it appropriate
* to provide support for JSON nulls. Yes, a small amount of memory is
* allocated just to point to a NULL, but this keeps all the APIs
* clean.
*
* Return: A JsonValue that represents a JSON null, or NULL if memory
* could not be allocated.
*/
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extern JsonValue *
JsonValueNull(void);
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/*
* Free the memory being used by a JSON value. Note that this will
* recursively free all Arrays, HashMaps, and other JsonValues that
* are reachable from this one. It will invoke free() on strings as
* well, so make sure passed string pointers point to strings on the
* heap, not the stack. This will be the case for all strings returned
* by JsonDecode(), which is why this assumption is made. However, if
* you are manually creating JsonObjects and stitching them together,
* you'll have to manually free them as well. Calling this on a
* JsonValue that contains a pointer to a stack string is undefined.
*
* Params:
*
* (JsonValue *) The JsonValue to recursively free.
*/
extern void
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JsonValueFree(JsonValue *);
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/*
* Recursively free a HashMap of JsonValues. This iterates over all
* the JsonValues in a HashMap and frees them using JsonValueFree(),
* which will in turn call JsonFree() on values of type JSON_OBJECT.
*
* Params:
*
* (HashMap *) The hash map of JsonValues to recursively free.
*/
extern void
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JsonFree(HashMap *);
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/*
* Encode the given string in such a way that it can be embedded in a
* JSON stream. This entails:
*
* - Escaping quotes, backslashes, and other special characters using
* their backslash escape
* - Encoding bytes that are not UTF-8 using \u escapes.
* - Wrapping the entire string in double quotes.
*
* This function is provided via the public API so it is accessible to
* custom JSON encoders, such as the CanonicalJson API. This will
* typically be used for encoding JSON keys; for values, just use
* JsonEncodeValue().
*
* Params:
*
* (const char *) The C string to serialize as a JSON string.
* (FILE *) The output stream to write the encoded string to.
*/
extern void
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JsonEncodeString(const char *, FILE *);
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/*
* Serialize a JsonValue as it would appear in JSON output. This is
* a recursive function that will also encode all child values
* reachable from the given JsonValue.
*
* This is exposed via the public API so that custom JSON encoders
* such as CanonicalJson can take advantage of it. Normal users that
* are writing custom encoders should just use JsonEncode() to encode
* an entire object.
*
* Params:
*
* (JsonValue *) The value to encode.
* (FILE *) The output stream to write the given value to.
*/
extern void
JsonEncodeValue(JsonValue * value, FILE * out);
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/*
* Encode a HashMap of JsonValues into a fully-valid, minimized JSON
* object. This function is recursive; it will serialize everything
* accessible from the passed object into JSON.
*
* Params:
*
* (HashMap *) The HashMap of JsonValues to encode and write to the
* output stream.
* (FILE *) The output stream to write the given HashMap to.
*
* Return: Whether or not the operation was successful. This function
* will fail if either the passed HashMap or file stream are NULL. In
* all other cases, this function succeeds.
*/
extern int
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JsonEncode(HashMap *, FILE *);
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/*
* Decode the given input stream into a HashMap of JsonValues.
*
* Params:
*
* (FILE *) The input stream to parse JSON from.
*
* Return: A HashMap of JsonValues, or NULL if there was an error
* parsing the JSON.
*/
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extern HashMap *
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JsonDecode(FILE *);
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#endif /* TELODENDRIA_JSON_H */