JSON print/parse

Namespaces
	epics::pvData::yajl

Classes
struct	epics::pvData::JSONPrintOptions
	Options used during printing. More...

Functions
void	epics::pvData::printJSON (std::ostream &strm, const PVStructure &val, const BitSet &mask, const JSONPrintOptions &opts)
void	epics::pvData::printJSON (std::ostream &strm, const PVField &val, const JSONPrintOptions &opts)
FORCE_INLINE void	epics::pvData::printJSON (std::ostream &strm, const PVField::const_shared_pointer &val, const JSONPrintOptions &opts=JSONPrintOptions())
epics::pvData::PVStructure::shared_pointer	epics::pvData::parseJSON (std::istream &strm)
epicsShareFunc void	epics::pvData::parseJSON (std::istream &strm, PVField &dest, BitSet *assigned)
FORCE_INLINE void	epics::pvData::parseJSON (std::istream &strm, const PVField::shared_pointer &dest, BitSet *assigned=0)
bool	epics::pvData::yajl_parse_helper (std::istream &src, yajl_handle handle)

Detailed Description

Printing PVField as JSON and parsing JSON into PVField.

Function Documentation

FORCE_INLINE void epics::pvData::parseJSON	(	std::istream &	strm,
		const PVField::shared_pointer &	dest,
		BitSet *	assigned = 0
	)

Definition at line 109 of file json.h.

{
    parseJSON(strm, *dest, assigned);
}

epicsShareFunc PVStructure::shared_pointer epics::pvData::parseJSON

(

std::istream &

strm

)

Parse JSON text into a PVStructure

Restrictions:

• Top level must be {} dict/object
• field values must be number, string, array, or dict/object
• array values must be number or string

Definition at line 255 of file parseany.cpp.

{
#ifndef EPICS_YAJL_VERSION
    yajl_parser_config conf;
    memset(&conf, 0, sizeof(conf));
    conf.allowComments = 1;
    conf.checkUTF8 = 1;
#endif

    context ctxt;

#ifndef EPICS_YAJL_VERSION
    handler handle(yajl_alloc(&jtree_cbs, &conf, NULL, &ctxt));
#else
    handler handle(yajl_alloc(&jtree_cbs, NULL, &ctxt));

    yajl_config(handle, yajl_allow_comments, 1);
#endif

    if(!yajl_parse_helper(strm, handle))
        throw std::runtime_error(ctxt.msg);

    return ctxt.cur->buildPVStructure();
}

epicsShareFunc void epics::pvData::parseJSON	(	std::istream &	strm,
		PVField &	dest,
		BitSet *	assigned = 0
	)

Parse JSON and store into the provided PVStructure.

Restrictions:

• array of union not supported
• Only scalar value assigned to union

Parameters

strm	Read JSON text from stream
dest	Store in fields of this structure
assigned	Which fields of dest were assigned. (Optional)

Exceptions

std::runtime_error

on failure. dest and assigned may be modified.

Version

Overload added after 7.0.0

Definition at line 311 of file parseinto.cpp.

{
#ifndef EPICS_YAJL_VERSION
    yajl_parser_config conf;
    memset(&conf, 0, sizeof(conf));
    conf.allowComments = 1;
    conf.checkUTF8 = 1;
#endif

    // we won't create refs to 'dest' which presist beyond this call.
    // however, it is convienent to treat 'dest' in the same manner as
    // any union/structureArray memebers it may contain.
    PVFieldPtr fakedest(&dest, noop());

    context ctxt(fakedest, assigned);

#ifndef EPICS_YAJL_VERSION
    handler handle(yajl_alloc(&jtree_cbs, &conf, NULL, &ctxt));
#else
    handler handle(yajl_alloc(&jtree_cbs, NULL, &ctxt));

    yajl_config(handle, yajl_allow_comments, 1);
#endif


    if(!yajl_parse_helper(strm, handle))
        throw std::runtime_error(ctxt.msg);

    if(!ctxt.stack.empty())
        throw std::logic_error("field stack not empty");
    assert(fakedest.use_count()==1);
}

FORCE_INLINE void epics::pvData::printJSON	(	std::ostream &	strm,
		const PVField::const_shared_pointer &	val,
		const JSONPrintOptions &	opts = JSONPrintOptions()
	)

Definition at line 71 of file json.h.

{
    printJSON(strm, *val, opts);
}

epicsShareFunc void epics::pvData::printJSON	(	std::ostream &	strm,
		const PVStructure &	val,
		const BitSet &	mask,
		const JSONPrintOptions &	opts = JSONPrintOptions()
	)

Print PVStructure as JSON

'mask' selects those fields which will be printed.

Version

Overload added after 7.0.0

Definition at line 211 of file print.cpp.

{
    args A(strm, opts);
    pvd::BitSet emask(mask);
    expandBS(val, emask, true);
    if(!emask.get(0)) return;
    show_struct(A, &val, &emask);
}

epicsShareFunc void epics::pvData::printJSON	(	std::ostream &	strm,
		const PVField &	val,
		const JSONPrintOptions &	opts = JSONPrintOptions()
	)

Print PVField as JSON

Version

Overload added after 7.0.0

Definition at line 223 of file print.cpp.

{
    args A(strm, opts);
    show_field(A, &val, 0);
}

epicsShareFunc bool epics::pvData::yajl_parse_helper	(	std::istream &	src,
		yajl_handle	handle
	)

Wrapper around yajl_parse()

Parse entire input stream. Errors if extranious non-whitespace found after the point were parsing completes.

Parameters

src	The stream from which input charactors are read
handle	A parser handle previously allocated with yajl_alloc(). Not free'd on success or failure.

Returns

true if parsing completes successfully. false if parsing cancelled by callback. throws other errors

Note

The form of this call depends on EPICS_YAJL_VERSION

Definition at line 29 of file parsehelper.cpp.

{
    unsigned linenum=0;
#ifndef EPICS_YAJL_VERSION
    bool done = false;
#endif

    std::string line;
    while(std::getline(src, line)) {
        linenum++;

#ifndef EPICS_YAJL_VERSION
        if(done) {
            check_trailing(line);
            continue;
        }
#endif

        yajl_status sts = yajl_parse(handle, (const unsigned char*)line.c_str(), line.size());

        switch(sts) {
        case yajl_status_ok: {
            size_t consumed = yajl_get_bytes_consumed(handle);

            if(consumed<line.size()) {
                check_trailing(line.substr(consumed));
            }

#ifndef EPICS_YAJL_VERSION
            done = true;
#endif
            break;
        }
        case yajl_status_client_canceled:
            return false;
#ifndef EPICS_YAJL_VERSION
        case yajl_status_insufficient_data:
            // continue with next line
            break;
#endif
        case yajl_status_error:
        {
            std::ostringstream msg;
            unsigned char *raw = yajl_get_error(handle, 1, (const unsigned char*)line.c_str(), line.size());
            if(!raw) {
                msg<<"Unknown error on line "<<linenum;
            } else {
                try {
                    msg<<"Error on line "<<linenum<<" : "<<(const char*)raw;
                }catch(...){
                    yajl_free_error(handle, raw);
                    throw;
                }
                yajl_free_error(handle, raw);
            }
            throw std::runtime_error(msg.str());
        }
        }
    }

    if(!src.eof() || src.bad()) {
        std::ostringstream msg;
        msg<<"I/O error after line "<<linenum;
        throw std::runtime_error(msg.str());

#ifndef EPICS_YAJL_VERSION
    } else if(!done) {
        switch(yajl_parse_complete(handle)) {
#else
    } else {
        switch(yajl_complete_parse(handle)) {
#endif
        case yajl_status_ok:
            break;
        case yajl_status_client_canceled:
            return false;
#ifndef EPICS_YAJL_VERSION
        case yajl_status_insufficient_data:
            throw std::runtime_error("unexpected end of input");
#endif
        case yajl_status_error:
            throw std::runtime_error("Error while completing parsing");
        }
    }

    return true;
}