netcdf-c/include/ncjson.h
Dennis Heimbigner 11fe00ea05 Add filter support to NCZarr
Filter support has three goals:

1. Use the existing HDF5 filter implementations,
2. Allow filter metadata to be stored in the NumCodecs metadata format used by Zarr,
3. Allow filters to be used even when HDF5 is disabled

Detailed usage directions are define in docs/filters.md.

For now, the existing filter API is left in place. So filters
are defined using ''nc_def_var_filter'' using the HDF5 style
where the id and parameters are unsigned integers.

This is a big change since filters affect many parts of the code.

In the following, the terms "compressor" and "filter" and "codec" are generally
used synonomously.

### Filter-Related Changes:
* In order to support dynamic loading of shared filter libraries, a new library was added in the libncpoco directory; it helps to isolate dynamic loading across multiple platforms.
* Provide a json parsing library for use by plugins; this is created by merging libdispatch/ncjson.c with include/ncjson.h.
* Add a new _Codecs attribute to allow clients to see what codecs are being used; let ncdump -s print it out.
* Provide special headers to help support compilation of HDF5 filters when HDF5 is not enabled: netcdf_filter_hdf5_build.h and netcdf_filter_build.h.
* Add a number of new test to test the new nczarr filters.
* Let ncgen parse _Codecs attribute, although it is ignored.

### Plugin directory changes:
* Add support for the Blosc compressor; this is essential because it is the most common compressor used in Zarr datasets. This also necessitated adding a CMake FindBlosc.cmake file
* Add NCZarr support for the big-four filters provided by HDF5: shuffle, fletcher32, deflate (zlib), and szip
* Add a Codec defaulter (see docs/filters.md) for the big four filters.
* Make plugins work with windows by properly adding __declspec declaration.

### Misc. Non-Filter Changes
* Replace most uses of USE_NETCDF4 (deprecated) with USE_HDF5.
* Improve support for caching
* More fixes for path conversion code
* Fix misc. memory leaks
* Add new utility -- ncdump/ncpathcvt -- that does more or less the same thing as cygpath.
* Add a number of new test to test the non-filter fixes.
* Update the parsers
* Convert most instances of '#ifdef _MSC_VER' to '#ifdef _WIN32'
2021-09-02 17:04:26 -06:00

125 lines
3.6 KiB
C

/* Copyright 2018, UCAR/Unidata.
See the COPYRIGHT file for more information.
*/
#ifndef NCJSON_H
#define NCJSON_H 1
#ifndef DLLEXPORT
#ifdef _WIN32
#define DLLEXPORT __declspec(dllexport)
#else
#define DLLEXPORT
#endif
#endif
/**************************************************/
/* Json object sorts (note use of term sort rather than e.g. type or discriminant) */
#define NCJ_UNDEF 0
#define NCJ_STRING 1
#define NCJ_INT 2
#define NCJ_DOUBLE 3
#define NCJ_BOOLEAN 4
#define NCJ_DICT 5
#define NCJ_ARRAY 6
#define NCJ_NULL 7
#define NCJ_NSORTS 8
/* No flags are currently defined, but the argument is a placeholder */
/* Define a struct to store primitive values as unquoted
strings. The sort will provide more info. Do not bother with
a union since the amount of saved space is minimal.
*/
typedef struct NCjson {
int sort; /* of this object */
char* string; /* sort != DICT|ARRAY */
struct NCjlist {
int len;
struct NCjson** contents;
} list; /* sort == DICT|ARRAY */
} NCjson;
/* Structure to hold result of convertinf one json sort to value of another type;
don't use union so we can know when to reclaim sval
*/
struct NCJconst {int bval; long long ival; double dval; char* sval;};
/**************************************************/
/* Extended API */
/* Return 0 if ok else -1 */
#if defined(__cplusplus)
extern "C" {
#endif
/* Parse a JSON string */
DLLEXPORT int NCJparse(const char* text, unsigned flags, NCjson** jsonp);
/* Reclaim a JSON tree */
DLLEXPORT extern void NCJreclaim(NCjson* json);
/* Create a new JSON node of a given sort */
DLLEXPORT extern int NCJnew(int sort, NCjson** objectp);
/* Create new json object with given string content */
DLLEXPORT extern int NCJnewstring(int sort, const char* value, NCjson** jsonp);
/* Create new json object with given counted string content */
DLLEXPORT extern int NCJnewstringn(int sort, size_t len, const char* value, NCjson** jsonp);
/* Get dict key value by name */
DLLEXPORT extern int NCJdictget(const NCjson* dict, const char* key, NCjson** valuep);
/* Convert one json sort to value of another type; don't use union so we can know when to reclaim sval */
DLLEXPORT extern int NCJcvt(const NCjson* value, int outsort, struct NCJconst* output);
#ifndef NETCDF_JSON_H
/* Insert an atomic value to an array or dict object. */
DLLEXPORT int NCJaddstring(NCjson* json, int sort, const char* s);
/* Append value to an array or dict object. */
DLLEXPORT extern int NCJappend(NCjson* object, NCjson* value);
/* Insert key-value pair into a dict object. key will be copied */
DLLEXPORT extern int NCJinsert(NCjson* object, char* key, NCjson* value);
/* Unparser to convert NCjson object to text in buffer */
DLLEXPORT extern int NCJunparse(const NCjson* json, unsigned flags, char** textp);
/* Deep clone a json object */
DLLEXPORT extern int NCJclone(const NCjson* json, NCjson** clonep);
/* dump NCjson* object to output file */
DLLEXPORT extern void NCJdump(const NCjson* json, unsigned flags, FILE*);
#endif
#if defined(__cplusplus)
}
#endif
/* Getters */
#define NCJsort(x) ((x)->sort)
#define NCJstring(x) ((x)->string)
#define NCJlength(x) ((x)==NULL ? 0 : (x)->list.len)
#define NCJcontents(x) ((x)->list.contents)
#define NCJith(x,i) ((x)->list.contents[i])
/* Setters */
#define NCJsetsort(x,s) (x)->sort=(s)
#define NCJsetstring(x,y) (x)->string=(y)
#define NCJsetcontents(x,c) (x)->list.contents=(c)
#define NCJsetlength(x,l) (x)->list.len=(l)
/* Misc */
#define NCJisatomic(j) ((j)->sort != NCJ_ARRAY && (j)->sort != NCJ_DICT && (j)->sort != NCJ_NULL && (j)->sort != NCJ_UNDEF)
/**************************************************/
#endif /*NCJSON_H*/