jsonb.c

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/*-------------------------------------------------------------------------
 *
 * jsonb.c
 *      I/O routines for jsonb type
 *
 * Copyright (c) 2014-2019, PostgreSQL Global Development Group
 *
 * IDENTIFICATION
 *    src/backend/utils/adt/jsonb.c
 *
 *-------------------------------------------------------------------------
 */
#include "postgres.h"

#include "miscadmin.h"
#include "access/htup_details.h"
#include "access/transam.h"
#include "catalog/pg_type.h"
#include "funcapi.h"
#include "libpq/pqformat.h"
#include "parser/parse_coerce.h"
#include "utils/builtins.h"
#include "utils/date.h"
#include "utils/datetime.h"
#include "utils/lsyscache.h"
#include "utils/json.h"
#include "utils/jsonapi.h"
#include "utils/jsonb.h"
#include "utils/syscache.h"
#include "utils/typcache.h"

typedef struct JsonbInState
{
    JsonbParseState *parseState;
    JsonbValue *res;
} JsonbInState;

/* unlike with json categories, we need to treat json and jsonb differently */
typedef enum                    /* type categories for datum_to_jsonb */
{
    JSONBTYPE_NULL,             /* null, so we didn't bother to identify */
    JSONBTYPE_BOOL,             /* boolean (built-in types only) */
    JSONBTYPE_NUMERIC,          /* numeric (ditto) */
    JSONBTYPE_DATE,             /* we use special formatting for datetimes */
    JSONBTYPE_TIMESTAMP,        /* we use special formatting for timestamp */
    JSONBTYPE_TIMESTAMPTZ,      /* ... and timestamptz */
    JSONBTYPE_JSON,             /* JSON */
    JSONBTYPE_JSONB,            /* JSONB */
    JSONBTYPE_ARRAY,            /* array */
    JSONBTYPE_COMPOSITE,        /* composite */
    JSONBTYPE_JSONCAST,         /* something with an explicit cast to JSON */
    JSONBTYPE_OTHER             /* all else */
} JsonbTypeCategory;

typedef struct JsonbAggState
{
    JsonbInState *res;
    JsonbTypeCategory key_category;
    Oid         key_output_func;
    JsonbTypeCategory val_category;
    Oid         val_output_func;
} JsonbAggState;

static inline Datum jsonb_from_cstring(char *json, int len);
static size_t checkStringLen(size_t len);
static void jsonb_in_object_start(void *pstate);
static void jsonb_in_object_end(void *pstate);
static void jsonb_in_array_start(void *pstate);
static void jsonb_in_array_end(void *pstate);
static void jsonb_in_object_field_start(void *pstate, char *fname, bool isnull);
static void jsonb_put_escaped_value(StringInfo out, JsonbValue *scalarVal);
static void jsonb_in_scalar(void *pstate, char *token, JsonTokenType tokentype);
static void jsonb_categorize_type(Oid typoid,
                                  JsonbTypeCategory *tcategory,
                                  Oid *outfuncoid);
static void composite_to_jsonb(Datum composite, JsonbInState *result);
static void array_dim_to_jsonb(JsonbInState *result, int dim, int ndims, int *dims,
                               Datum *vals, bool *nulls, int *valcount,
                               JsonbTypeCategory tcategory, Oid outfuncoid);
static void array_to_jsonb_internal(Datum array, JsonbInState *result);
static void jsonb_categorize_type(Oid typoid,
                                  JsonbTypeCategory *tcategory,
                                  Oid *outfuncoid);
static void datum_to_jsonb(Datum val, bool is_null, JsonbInState *result,
                           JsonbTypeCategory tcategory, Oid outfuncoid,
                           bool key_scalar);
static void add_jsonb(Datum val, bool is_null, JsonbInState *result,
                      Oid val_type, bool key_scalar);
static JsonbParseState *clone_parse_state(JsonbParseState *state);
static char *JsonbToCStringWorker(StringInfo out, JsonbContainer *in, int estimated_len, bool indent);
static void add_indent(StringInfo out, bool indent, int level);

/*
 * jsonb type input function
 */
Datum
jsonb_in(PG_FUNCTION_ARGS)
{
    char       *json = PG_GETARG_CSTRING(0);

    return jsonb_from_cstring(json, strlen(json));
}

/*
 * jsonb type recv function
 *
 * The type is sent as text in binary mode, so this is almost the same
 * as the input function, but it's prefixed with a version number so we
 * can change the binary format sent in future if necessary. For now,
 * only version 1 is supported.
 */
Datum
jsonb_recv(PG_FUNCTION_ARGS)
{
    StringInfo  buf = (StringInfo) PG_GETARG_POINTER(0);
    int         version = pq_getmsgint(buf, 1);
    char       *str;
    int         nbytes;

    if (version == 1)
        str = pq_getmsgtext(buf, buf->len - buf->cursor, &nbytes);
    else
        elog(ERROR, "unsupported jsonb version number %d", version);

    return jsonb_from_cstring(str, nbytes);
}

/*
 * jsonb type output function
 */
Datum
jsonb_out(PG_FUNCTION_ARGS)
{
    Jsonb      *jb = PG_GETARG_JSONB_P(0);
    char       *out;

    out = JsonbToCString(NULL, &jb->root, VARSIZE(jb));

    PG_RETURN_CSTRING(out);
}

/*
 * jsonb type send function
 *
 * Just send jsonb as a version number, then a string of text
 */
Datum
jsonb_send(PG_FUNCTION_ARGS)
{
    Jsonb      *jb = PG_GETARG_JSONB_P(0);
    StringInfoData buf;
    StringInfo  jtext = makeStringInfo();
    int         version = 1;

    (void) JsonbToCString(jtext, &jb->root, VARSIZE(jb));

    pq_begintypsend(&buf);
    pq_sendint8(&buf, version);
    pq_sendtext(&buf, jtext->data, jtext->len);
    pfree(jtext->data);
    pfree(jtext);

    PG_RETURN_BYTEA_P(pq_endtypsend(&buf));
}

/*
 * Get the type name of a jsonb container.
 */
static const char *
JsonbContainerTypeName(JsonbContainer *jbc)
{
    JsonbValue  scalar;

    if (JsonbExtractScalar(jbc, &scalar))
        return JsonbTypeName(&scalar);
    else if (JsonContainerIsArray(jbc))
        return "array";
    else if (JsonContainerIsObject(jbc))
        return "object";
    else
    {
        elog(ERROR, "invalid jsonb container type: 0x%08x", jbc->header);
        return "unknown";
    }
}

/*
 * Get the type name of a jsonb value.
 */
const char *
JsonbTypeName(JsonbValue *jbv)
{
    switch (jbv->type)
    {
        case jbvBinary:
            return JsonbContainerTypeName(jbv->val.binary.data);
        case jbvObject:
            return "object";
        case jbvArray:
            return "array";
        case jbvNumeric:
            return "number";
        case jbvString:
            return "string";
        case jbvBool:
            return "boolean";
        case jbvNull:
            return "null";
        default:
            elog(ERROR, "unrecognized jsonb value type: %d", jbv->type);
            return "unknown";
    }
}

/*
 * SQL function jsonb_typeof(jsonb) -> text
 *
 * This function is here because the analog json function is in json.c, since
 * it uses the json parser internals not exposed elsewhere.
 */
Datum
jsonb_typeof(PG_FUNCTION_ARGS)
{
    Jsonb      *in = PG_GETARG_JSONB_P(0);
    const char *result = JsonbContainerTypeName(&in->root);

    PG_RETURN_TEXT_P(cstring_to_text(result));
}

/*
 * jsonb_from_cstring
 *
 * Turns json string into a jsonb Datum.
 *
 * Uses the json parser (with hooks) to construct a jsonb.
 */
static inline Datum
jsonb_from_cstring(char *json, int len)
{
    JsonLexContext *lex;
    JsonbInState state;
    JsonSemAction sem;

    memset(&state, 0, sizeof(state));
    memset(&sem, 0, sizeof(sem));
    lex = makeJsonLexContextCstringLen(json, len, true);

    sem.semstate = (void *) &state;

    sem.object_start = jsonb_in_object_start;
    sem.array_start = jsonb_in_array_start;
    sem.object_end = jsonb_in_object_end;
    sem.array_end = jsonb_in_array_end;
    sem.scalar = jsonb_in_scalar;
    sem.object_field_start = jsonb_in_object_field_start;

    pg_parse_json(lex, &sem);

    /* after parsing, the item member has the composed jsonb structure */
    PG_RETURN_POINTER(JsonbValueToJsonb(state.res));
}

static size_t
checkStringLen(size_t len)
{
    if (len > JENTRY_OFFLENMASK)
        ereport(ERROR,
                (errcode(ERRCODE_PROGRAM_LIMIT_EXCEEDED),
                 errmsg("string too long to represent as jsonb string"),
                 errdetail("Due to an implementation restriction, jsonb strings cannot exceed %d bytes.",
                           JENTRY_OFFLENMASK)));

    return len;
}

static void
jsonb_in_object_start(void *pstate)
{
    JsonbInState *_state = (JsonbInState *) pstate;

    _state->res = pushJsonbValue(&_state->parseState, WJB_BEGIN_OBJECT, NULL);
}

static void
jsonb_in_object_end(void *pstate)
{
    JsonbInState *_state = (JsonbInState *) pstate;

    _state->res = pushJsonbValue(&_state->parseState, WJB_END_OBJECT, NULL);
}

static void
jsonb_in_array_start(void *pstate)
{
    JsonbInState *_state = (JsonbInState *) pstate;

    _state->res = pushJsonbValue(&_state->parseState, WJB_BEGIN_ARRAY, NULL);
}

static void
jsonb_in_array_end(void *pstate)
{
    JsonbInState *_state = (JsonbInState *) pstate;

    _state->res = pushJsonbValue(&_state->parseState, WJB_END_ARRAY, NULL);
}

static void
jsonb_in_object_field_start(void *pstate, char *fname, bool isnull)
{
    JsonbInState *_state = (JsonbInState *) pstate;
    JsonbValue  v;

    Assert(fname != NULL);
    v.type = jbvString;
    v.val.string.len = checkStringLen(strlen(fname));
    v.val.string.val = fname;

    _state->res = pushJsonbValue(&_state->parseState, WJB_KEY, &v);
}

static void
jsonb_put_escaped_value(StringInfo out, JsonbValue *scalarVal)
{
    switch (scalarVal->type)
    {
        case jbvNull:
            appendBinaryStringInfo(out, "null", 4);
            break;
        case jbvString:
            escape_json(out, pnstrdup(scalarVal->val.string.val, scalarVal->val.string.len));
            break;
        case jbvNumeric:
            appendStringInfoString(out,
                                   DatumGetCString(DirectFunctionCall1(numeric_out,
                                                                       PointerGetDatum(scalarVal->val.numeric))));
            break;
        case jbvBool:
            if (scalarVal->val.boolean)
                appendBinaryStringInfo(out, "true", 4);
            else
                appendBinaryStringInfo(out, "false", 5);
            break;
        default:
            elog(ERROR, "unknown jsonb scalar type");
    }
}

/*
 * For jsonb we always want the de-escaped value - that's what's in token
 */
static void
jsonb_in_scalar(void *pstate, char *token, JsonTokenType tokentype)
{
    JsonbInState *_state = (JsonbInState *) pstate;
    JsonbValue  v;
    Datum       numd;

    switch (tokentype)
    {

        case JSON_TOKEN_STRING:
            Assert(token != NULL);
            v.type = jbvString;
            v.val.string.len = checkStringLen(strlen(token));
            v.val.string.val = token;
            break;
        case JSON_TOKEN_NUMBER:

            /*
             * No need to check size of numeric values, because maximum
             * numeric size is well below the JsonbValue restriction
             */
            Assert(token != NULL);
            v.type = jbvNumeric;
            numd = DirectFunctionCall3(numeric_in,
                                       CStringGetDatum(token),
                                       ObjectIdGetDatum(InvalidOid),
                                       Int32GetDatum(-1));
            v.val.numeric = DatumGetNumeric(numd);
            break;
        case JSON_TOKEN_TRUE:
            v.type = jbvBool;
            v.val.boolean = true;
            break;
        case JSON_TOKEN_FALSE:
            v.type = jbvBool;
            v.val.boolean = false;
            break;
        case JSON_TOKEN_NULL:
            v.type = jbvNull;
            break;
        default:
            /* should not be possible */
            elog(ERROR, "invalid json token type");
            break;
    }

    if (_state->parseState == NULL)
    {
        /* single scalar */
        JsonbValue  va;

        va.type = jbvArray;
        va.val.array.rawScalar = true;
        va.val.array.nElems = 1;

        _state->res = pushJsonbValue(&_state->parseState, WJB_BEGIN_ARRAY, &va);
        _state->res = pushJsonbValue(&_state->parseState, WJB_ELEM, &v);
        _state->res = pushJsonbValue(&_state->parseState, WJB_END_ARRAY, NULL);
    }
    else
    {
        JsonbValue *o = &_state->parseState->contVal;

        switch (o->type)
        {
            case jbvArray:
                _state->res = pushJsonbValue(&_state->parseState, WJB_ELEM, &v);
                break;
            case jbvObject:
                _state->res = pushJsonbValue(&_state->parseState, WJB_VALUE, &v);
                break;
            default:
                elog(ERROR, "unexpected parent of nested structure");
        }
    }
}

/*
 * JsonbToCString
 *     Converts jsonb value to a C-string.
 *
 * If 'out' argument is non-null, the resulting C-string is stored inside the
 * StringBuffer.  The resulting string is always returned.
 *
 * A typical case for passing the StringInfo in rather than NULL is where the
 * caller wants access to the len attribute without having to call strlen, e.g.
 * if they are converting it to a text* object.
 */
char *
JsonbToCString(StringInfo out, JsonbContainer *in, int estimated_len)
{
    return JsonbToCStringWorker(out, in, estimated_len, false);
}

/*
 * same thing but with indentation turned on
 */
char *
JsonbToCStringIndent(StringInfo out, JsonbContainer *in, int estimated_len)
{
    return JsonbToCStringWorker(out, in, estimated_len, true);
}

/*
 * common worker for above two functions
 */
static char *
JsonbToCStringWorker(StringInfo out, JsonbContainer *in, int estimated_len, bool indent)
{
    bool        first = true;
    JsonbIterator *it;
    JsonbValue  v;
    JsonbIteratorToken type = WJB_DONE;
    int         level = 0;
    bool        redo_switch = false;

    /* If we are indenting, don't add a space after a comma */
    int         ispaces = indent ? 1 : 2;

    /*
     * Don't indent the very first item. This gets set to the indent flag at
     * the bottom of the loop.
     */
    bool        use_indent = false;
    bool        raw_scalar = false;
    bool        last_was_key = false;

    if (out == NULL)
        out = makeStringInfo();

    enlargeStringInfo(out, (estimated_len >= 0) ? estimated_len : 64);

    it = JsonbIteratorInit(in);

    while (redo_switch ||
           ((type = JsonbIteratorNext(&it, &v, false)) != WJB_DONE))
    {
        redo_switch = false;
        switch (type)
        {
            case WJB_BEGIN_ARRAY:
                if (!first)
                    appendBinaryStringInfo(out, ", ", ispaces);

                if (!v.val.array.rawScalar)
                {
                    add_indent(out, use_indent && !last_was_key, level);
                    appendStringInfoCharMacro(out, '[');
                }
                else
                    raw_scalar = true;

                first = true;
                level++;
                break;
            case WJB_BEGIN_OBJECT:
                if (!first)
                    appendBinaryStringInfo(out, ", ", ispaces);

                add_indent(out, use_indent && !last_was_key, level);
                appendStringInfoCharMacro(out, '{');

                first = true;
                level++;
                break;
            case WJB_KEY:
                if (!first)
                    appendBinaryStringInfo(out, ", ", ispaces);
                first = true;

                add_indent(out, use_indent, level);

                /* json rules guarantee this is a string */
                jsonb_put_escaped_value(out, &v);
                appendBinaryStringInfo(out, ": ", 2);

                type = JsonbIteratorNext(&it, &v, false);
                if (type == WJB_VALUE)
                {
                    first = false;
                    jsonb_put_escaped_value(out, &v);
                }
                else
                {
                    Assert(type == WJB_BEGIN_OBJECT || type == WJB_BEGIN_ARRAY);

                    /*
                     * We need to rerun the current switch() since we need to
                     * output the object which we just got from the iterator
                     * before calling the iterator again.
                     */
                    redo_switch = true;
                }
                break;
            case WJB_ELEM:
                if (!first)
                    appendBinaryStringInfo(out, ", ", ispaces);
                first = false;

                if (!raw_scalar)
                    add_indent(out, use_indent, level);
                jsonb_put_escaped_value(out, &v);
                break;
            case WJB_END_ARRAY:
                level--;
                if (!raw_scalar)
                {
                    add_indent(out, use_indent, level);
                    appendStringInfoCharMacro(out, ']');
                }
                first = false;
                break;
            case WJB_END_OBJECT:
                level--;
                add_indent(out, use_indent, level);
                appendStringInfoCharMacro(out, '}');
                first = false;
                break;
            default:
                elog(ERROR, "unknown jsonb iterator token type");
        }
        use_indent = indent;
        last_was_key = redo_switch;
    }

    Assert(level == 0);

    return out->data;
}

static void
add_indent(StringInfo out, bool indent, int level)
{
    if (indent)
    {
        int         i;

        appendStringInfoCharMacro(out, '\n');
        for (i = 0; i < level; i++)
            appendBinaryStringInfo(out, "    ", 4);
    }
}


/*
 * Determine how we want to render values of a given type in datum_to_jsonb.
 *
 * Given the datatype OID, return its JsonbTypeCategory, as well as the type's
 * output function OID.  If the returned category is JSONBTYPE_JSONCAST,
 * we return the OID of the relevant cast function instead.
 */
static void
jsonb_categorize_type(Oid typoid,
                      JsonbTypeCategory *tcategory,
                      Oid *outfuncoid)
{
    bool        typisvarlena;

    /* Look through any domain */
    typoid = getBaseType(typoid);

    *outfuncoid = InvalidOid;

    /*
     * We need to get the output function for everything except date and
     * timestamp types, booleans, array and composite types, json and jsonb,
     * and non-builtin types where there's a cast to json. In this last case
     * we return the oid of the cast function instead.
     */

    switch (typoid)
    {
        case BOOLOID:
            *tcategory = JSONBTYPE_BOOL;
            break;

        case INT2OID:
        case INT4OID:
        case INT8OID:
        case FLOAT4OID:
        case FLOAT8OID:
        case NUMERICOID:
            getTypeOutputInfo(typoid, outfuncoid, &typisvarlena);
            *tcategory = JSONBTYPE_NUMERIC;
            break;

        case DATEOID:
            *tcategory = JSONBTYPE_DATE;
            break;

        case TIMESTAMPOID:
            *tcategory = JSONBTYPE_TIMESTAMP;
            break;

        case TIMESTAMPTZOID:
            *tcategory = JSONBTYPE_TIMESTAMPTZ;
            break;

        case JSONBOID:
            *tcategory = JSONBTYPE_JSONB;
            break;

        case JSONOID:
            *tcategory = JSONBTYPE_JSON;
            break;

        default:
            /* Check for arrays and composites */
            if (OidIsValid(get_element_type(typoid)) || typoid == ANYARRAYOID
                || typoid == RECORDARRAYOID)
                *tcategory = JSONBTYPE_ARRAY;
            else if (type_is_rowtype(typoid))   /* includes RECORDOID */
                *tcategory = JSONBTYPE_COMPOSITE;
            else
            {
                /* It's probably the general case ... */
                *tcategory = JSONBTYPE_OTHER;

                /*
                 * but first let's look for a cast to json (note: not to
                 * jsonb) if it's not built-in.
                 */
                if (typoid >= FirstNormalObjectId)
                {
                    Oid         castfunc;
                    CoercionPathType ctype;

                    ctype = find_coercion_pathway(JSONOID, typoid,
                                                  COERCION_EXPLICIT, &castfunc);
                    if (ctype == COERCION_PATH_FUNC && OidIsValid(castfunc))
                    {
                        *tcategory = JSONBTYPE_JSONCAST;
                        *outfuncoid = castfunc;
                    }
                    else
                    {
                        /* not a cast type, so just get the usual output func */
                        getTypeOutputInfo(typoid, outfuncoid, &typisvarlena);
                    }
                }
                else
                {
                    /* any other builtin type */
                    getTypeOutputInfo(typoid, outfuncoid, &typisvarlena);
                }
                break;
            }
    }
}

/*
 * Turn a Datum into jsonb, adding it to the result JsonbInState.
 *
 * tcategory and outfuncoid are from a previous call to json_categorize_type,
 * except that if is_null is true then they can be invalid.
 *
 * If key_scalar is true, the value is stored as a key, so insist
 * it's of an acceptable type, and force it to be a jbvString.
 */
static void
datum_to_jsonb(Datum val, bool is_null, JsonbInState *result,
               JsonbTypeCategory tcategory, Oid outfuncoid,
               bool key_scalar)
{
    char       *outputstr;
    bool        numeric_error;
    JsonbValue  jb;
    bool        scalar_jsonb = false;

    check_stack_depth();

    /* Convert val to a JsonbValue in jb (in most cases) */
    if (is_null)
    {
        Assert(!key_scalar);
        jb.type = jbvNull;
    }
    else if (key_scalar &&
             (tcategory == JSONBTYPE_ARRAY ||
              tcategory == JSONBTYPE_COMPOSITE ||
              tcategory == JSONBTYPE_JSON ||
              tcategory == JSONBTYPE_JSONB ||
              tcategory == JSONBTYPE_JSONCAST))
    {
        ereport(ERROR,
                (errcode(ERRCODE_INVALID_PARAMETER_VALUE),
                 errmsg("key value must be scalar, not array, composite, or json")));
    }
    else
    {
        if (tcategory == JSONBTYPE_JSONCAST)
            val = OidFunctionCall1(outfuncoid, val);

        switch (tcategory)
        {
            case JSONBTYPE_ARRAY:
                array_to_jsonb_internal(val, result);
                break;
            case JSONBTYPE_COMPOSITE:
                composite_to_jsonb(val, result);
                break;
            case JSONBTYPE_BOOL:
                if (key_scalar)
                {
                    outputstr = DatumGetBool(val) ? "true" : "false";
                    jb.type = jbvString;
                    jb.val.string.len = strlen(outputstr);
                    jb.val.string.val = outputstr;
                }
                else
                {
                    jb.type = jbvBool;
                    jb.val.boolean = DatumGetBool(val);
                }
                break;
            case JSONBTYPE_NUMERIC:
                outputstr = OidOutputFunctionCall(outfuncoid, val);
                if (key_scalar)
                {
                    /* always quote keys */
                    jb.type = jbvString;
                    jb.val.string.len = strlen(outputstr);
                    jb.val.string.val = outputstr;
                }
                else
                {
                    /*
                     * Make it numeric if it's a valid JSON number, otherwise
                     * a string. Invalid numeric output will always have an
                     * 'N' or 'n' in it (I think).
                     */
                    numeric_error = (strchr(outputstr, 'N') != NULL ||
                                     strchr(outputstr, 'n') != NULL);
                    if (!numeric_error)
                    {
                        Datum       numd;

                        jb.type = jbvNumeric;
                        numd = DirectFunctionCall3(numeric_in,
                                                   CStringGetDatum(outputstr),
                                                   ObjectIdGetDatum(InvalidOid),
                                                   Int32GetDatum(-1));
                        jb.val.numeric = DatumGetNumeric(numd);
                        pfree(outputstr);
                    }
                    else
                    {
                        jb.type = jbvString;
                        jb.val.string.len = strlen(outputstr);
                        jb.val.string.val = outputstr;
                    }
                }
                break;
            case JSONBTYPE_DATE:
                jb.type = jbvString;
                jb.val.string.val = JsonEncodeDateTime(NULL, val, DATEOID);
                jb.val.string.len = strlen(jb.val.string.val);
                break;
            case JSONBTYPE_TIMESTAMP:
                jb.type = jbvString;
                jb.val.string.val = JsonEncodeDateTime(NULL, val, TIMESTAMPOID);
                jb.val.string.len = strlen(jb.val.string.val);
                break;
            case JSONBTYPE_TIMESTAMPTZ:
                jb.type = jbvString;
                jb.val.string.val = JsonEncodeDateTime(NULL, val, TIMESTAMPTZOID);
                jb.val.string.len = strlen(jb.val.string.val);
                break;
            case JSONBTYPE_JSONCAST:
            case JSONBTYPE_JSON:
                {
                    /* parse the json right into the existing result object */
                    JsonLexContext *lex;
                    JsonSemAction sem;
                    text       *json = DatumGetTextPP(val);

                    lex = makeJsonLexContext(json, true);

                    memset(&sem, 0, sizeof(sem));

                    sem.semstate = (void *) result;

                    sem.object_start = jsonb_in_object_start;
                    sem.array_start = jsonb_in_array_start;
                    sem.object_end = jsonb_in_object_end;
                    sem.array_end = jsonb_in_array_end;
                    sem.scalar = jsonb_in_scalar;
                    sem.object_field_start = jsonb_in_object_field_start;

                    pg_parse_json(lex, &sem);

                }
                break;
            case JSONBTYPE_JSONB:
                {
                    Jsonb      *jsonb = DatumGetJsonbP(val);
                    JsonbIterator *it;

                    it = JsonbIteratorInit(&jsonb->root);

                    if (JB_ROOT_IS_SCALAR(jsonb))
                    {
                        (void) JsonbIteratorNext(&it, &jb, true);
                        Assert(jb.type == jbvArray);
                        (void) JsonbIteratorNext(&it, &jb, true);
                        scalar_jsonb = true;
                    }
                    else
                    {
                        JsonbIteratorToken type;

                        while ((type = JsonbIteratorNext(&it, &jb, false))
                               != WJB_DONE)
                        {
                            if (type == WJB_END_ARRAY || type == WJB_END_OBJECT ||
                                type == WJB_BEGIN_ARRAY || type == WJB_BEGIN_OBJECT)
                                result->res = pushJsonbValue(&result->parseState,
                                                             type, NULL);
                            else
                                result->res = pushJsonbValue(&result->parseState,
                                                             type, &jb);
                        }
                    }
                }
                break;
            default:
                outputstr = OidOutputFunctionCall(outfuncoid, val);
                jb.type = jbvString;
                jb.val.string.len = checkStringLen(strlen(outputstr));
                jb.val.string.val = outputstr;
                break;
        }
    }

    /* Now insert jb into result, unless we did it recursively */
    if (!is_null && !scalar_jsonb &&
        tcategory >= JSONBTYPE_JSON && tcategory <= JSONBTYPE_JSONCAST)
    {
        /* work has been done recursively */
        return;
    }
    else if (result->parseState == NULL)
    {
        /* single root scalar */
        JsonbValue  va;

        va.type = jbvArray;
        va.val.array.rawScalar = true;
        va.val.array.nElems = 1;

        result->res = pushJsonbValue(&result->parseState, WJB_BEGIN_ARRAY, &va);
        result->res = pushJsonbValue(&result->parseState, WJB_ELEM, &jb);
        result->res = pushJsonbValue(&result->parseState, WJB_END_ARRAY, NULL);
    }
    else
    {
        JsonbValue *o = &result->parseState->contVal;

        switch (o->type)
        {
            case jbvArray:
                result->res = pushJsonbValue(&result->parseState, WJB_ELEM, &jb);
                break;
            case jbvObject:
                result->res = pushJsonbValue(&result->parseState,
                                             key_scalar ? WJB_KEY : WJB_VALUE,
                                             &jb);
                break;
            default:
                elog(ERROR, "unexpected parent of nested structure");
        }
    }
}

/*
 * Process a single dimension of an array.
 * If it's the innermost dimension, output the values, otherwise call
 * ourselves recursively to process the next dimension.
 */
static void
array_dim_to_jsonb(JsonbInState *result, int dim, int ndims, int *dims, Datum *vals,
                   bool *nulls, int *valcount, JsonbTypeCategory tcategory,
                   Oid outfuncoid)
{
    int         i;

    Assert(dim < ndims);

    result->res = pushJsonbValue(&result->parseState, WJB_BEGIN_ARRAY, NULL);

    for (i = 1; i <= dims[dim]; i++)
    {
        if (dim + 1 == ndims)
        {
            datum_to_jsonb(vals[*valcount], nulls[*valcount], result, tcategory,
                           outfuncoid, false);
            (*valcount)++;
        }
        else
        {
            array_dim_to_jsonb(result, dim + 1, ndims, dims, vals, nulls,
                               valcount, tcategory, outfuncoid);
        }
    }

    result->res = pushJsonbValue(&result->parseState, WJB_END_ARRAY, NULL);
}

/*
 * Turn an array into JSON.
 */
static void
array_to_jsonb_internal(Datum array, JsonbInState *result)
{
    ArrayType  *v = DatumGetArrayTypeP(array);
    Oid         element_type = ARR_ELEMTYPE(v);
    int        *dim;
    int         ndim;
    int         nitems;
    int         count = 0;
    Datum      *elements;
    bool       *nulls;
    int16       typlen;
    bool        typbyval;
    char        typalign;
    JsonbTypeCategory tcategory;
    Oid         outfuncoid;

    ndim = ARR_NDIM(v);
    dim = ARR_DIMS(v);
    nitems = ArrayGetNItems(ndim, dim);

    if (nitems <= 0)
    {
        result->res = pushJsonbValue(&result->parseState, WJB_BEGIN_ARRAY, NULL);
        result->res = pushJsonbValue(&result->parseState, WJB_END_ARRAY, NULL);
        return;
    }

    get_typlenbyvalalign(element_type,
                         &typlen, &typbyval, &typalign);

    jsonb_categorize_type(element_type,
                          &tcategory, &outfuncoid);

    deconstruct_array(v, element_type, typlen, typbyval,
                      typalign, &elements, &nulls,
                      &nitems);

    array_dim_to_jsonb(result, 0, ndim, dim, elements, nulls, &count, tcategory,
                       outfuncoid);

    pfree(elements);
    pfree(nulls);
}

/*
 * Turn a composite / record into JSON.
 */
static void
composite_to_jsonb(Datum composite, JsonbInState *result)
{
    HeapTupleHeader td;
    Oid         tupType;
    int32       tupTypmod;
    TupleDesc   tupdesc;
    HeapTupleData tmptup,
               *tuple;
    int         i;

    td = DatumGetHeapTupleHeader(composite);

    /* Extract rowtype info and find a tupdesc */
    tupType = HeapTupleHeaderGetTypeId(td);
    tupTypmod = HeapTupleHeaderGetTypMod(td);
    tupdesc = lookup_rowtype_tupdesc(tupType, tupTypmod);

    /* Build a temporary HeapTuple control structure */
    tmptup.t_len = HeapTupleHeaderGetDatumLength(td);
    tmptup.t_data = td;
    tuple = &tmptup;

    result->res = pushJsonbValue(&result->parseState, WJB_BEGIN_OBJECT, NULL);

    for (i = 0; i < tupdesc->natts; i++)
    {
        Datum       val;
        bool        isnull;
        char       *attname;
        JsonbTypeCategory tcategory;
        Oid         outfuncoid;
        JsonbValue  v;
        Form_pg_attribute att = TupleDescAttr(tupdesc, i);

        if (att->attisdropped)
            continue;

        attname = NameStr(att->attname);

        v.type = jbvString;
        /* don't need checkStringLen here - can't exceed maximum name length */
        v.val.string.len = strlen(attname);
        v.val.string.val = attname;

        result->res = pushJsonbValue(&result->parseState, WJB_KEY, &v);

        val = heap_getattr(tuple, i + 1, tupdesc, &isnull);

        if (isnull)
        {
            tcategory = JSONBTYPE_NULL;
            outfuncoid = InvalidOid;
        }
        else
            jsonb_categorize_type(att->atttypid, &tcategory, &outfuncoid);

        datum_to_jsonb(val, isnull, result, tcategory, outfuncoid, false);
    }

    result->res = pushJsonbValue(&result->parseState, WJB_END_OBJECT, NULL);
    ReleaseTupleDesc(tupdesc);
}

/*
 * Append JSON text for "val" to "result".
 *
 * This is just a thin wrapper around datum_to_jsonb.  If the same type will be
 * printed many times, avoid using this; better to do the jsonb_categorize_type
 * lookups only once.
 */

static void
add_jsonb(Datum val, bool is_null, JsonbInState *result,
          Oid val_type, bool key_scalar)
{
    JsonbTypeCategory tcategory;
    Oid         outfuncoid;

    if (val_type == InvalidOid)
        ereport(ERROR,
                (errcode(ERRCODE_INVALID_PARAMETER_VALUE),
                 errmsg("could not determine input data type")));

    if (is_null)
    {
        tcategory = JSONBTYPE_NULL;
        outfuncoid = InvalidOid;
    }
    else
        jsonb_categorize_type(val_type,
                              &tcategory, &outfuncoid);

    datum_to_jsonb(val, is_null, result, tcategory, outfuncoid, key_scalar);
}

/*
 * SQL function to_jsonb(anyvalue)
 */
Datum
to_jsonb(PG_FUNCTION_ARGS)
{
    Datum       val = PG_GETARG_DATUM(0);
    Oid         val_type = get_fn_expr_argtype(fcinfo->flinfo, 0);
    JsonbInState result;
    JsonbTypeCategory tcategory;
    Oid         outfuncoid;

    if (val_type == InvalidOid)
        ereport(ERROR,
                (errcode(ERRCODE_INVALID_PARAMETER_VALUE),
                 errmsg("could not determine input data type")));

    jsonb_categorize_type(val_type,
                          &tcategory, &outfuncoid);

    memset(&result, 0, sizeof(JsonbInState));

    datum_to_jsonb(val, false, &result, tcategory, outfuncoid, false);

    PG_RETURN_POINTER(JsonbValueToJsonb(result.res));
}

/*
 * SQL function jsonb_build_object(variadic "any")
 */
Datum
jsonb_build_object(PG_FUNCTION_ARGS)
{
    int         nargs;
    int         i;
    JsonbInState result;
    Datum      *args;
    bool       *nulls;
    Oid        *types;

    /* build argument values to build the object */
    nargs = extract_variadic_args(fcinfo, 0, true, &args, &types, &nulls);

    if (nargs < 0)
        PG_RETURN_NULL();

    if (nargs % 2 != 0)
        ereport(ERROR,
                (errcode(ERRCODE_INVALID_PARAMETER_VALUE),
                 errmsg("argument list must have even number of elements"),
        /* translator: %s is a SQL function name */
                 errhint("The arguments of %s must consist of alternating keys and values.",
                         "jsonb_build_object()")));

    memset(&result, 0, sizeof(JsonbInState));

    result.res = pushJsonbValue(&result.parseState, WJB_BEGIN_OBJECT, NULL);

    for (i = 0; i < nargs; i += 2)
    {
        /* process key */
        if (nulls[i])
            ereport(ERROR,
                    (errcode(ERRCODE_INVALID_PARAMETER_VALUE),
                     errmsg("argument %d: key must not be null", i + 1)));

        add_jsonb(args[i], false, &result, types[i], true);

        /* process value */
        add_jsonb(args[i + 1], nulls[i + 1], &result, types[i + 1], false);
    }

    result.res = pushJsonbValue(&result.parseState, WJB_END_OBJECT, NULL);

    PG_RETURN_POINTER(JsonbValueToJsonb(result.res));
}

/*
 * degenerate case of jsonb_build_object where it gets 0 arguments.
 */
Datum
jsonb_build_object_noargs(PG_FUNCTION_ARGS)
{
    JsonbInState result;

    memset(&result, 0, sizeof(JsonbInState));

    (void) pushJsonbValue(&result.parseState, WJB_BEGIN_OBJECT, NULL);
    result.res = pushJsonbValue(&result.parseState, WJB_END_OBJECT, NULL);

    PG_RETURN_POINTER(JsonbValueToJsonb(result.res));
}

/*
 * SQL function jsonb_build_array(variadic "any")
 */
Datum
jsonb_build_array(PG_FUNCTION_ARGS)
{
    int         nargs;
    int         i;
    JsonbInState result;
    Datum      *args;
    bool       *nulls;
    Oid        *types;

    /* build argument values to build the array */
    nargs = extract_variadic_args(fcinfo, 0, true, &args, &types, &nulls);

    if (nargs < 0)
        PG_RETURN_NULL();

    memset(&result, 0, sizeof(JsonbInState));

    result.res = pushJsonbValue(&result.parseState, WJB_BEGIN_ARRAY, NULL);

    for (i = 0; i < nargs; i++)
        add_jsonb(args[i], nulls[i], &result, types[i], false);

    result.res = pushJsonbValue(&result.parseState, WJB_END_ARRAY, NULL);

    PG_RETURN_POINTER(JsonbValueToJsonb(result.res));
}

/*
 * degenerate case of jsonb_build_array where it gets 0 arguments.
 */
Datum
jsonb_build_array_noargs(PG_FUNCTION_ARGS)
{
    JsonbInState result;

    memset(&result, 0, sizeof(JsonbInState));

    (void) pushJsonbValue(&result.parseState, WJB_BEGIN_ARRAY, NULL);
    result.res = pushJsonbValue(&result.parseState, WJB_END_ARRAY, NULL);

    PG_RETURN_POINTER(JsonbValueToJsonb(result.res));
}


/*
 * SQL function jsonb_object(text[])
 *
 * take a one or two dimensional array of text as name value pairs
 * for a jsonb object.
 *
 */
Datum
jsonb_object(PG_FUNCTION_ARGS)
{
    ArrayType  *in_array = PG_GETARG_ARRAYTYPE_P(0);
    int         ndims = ARR_NDIM(in_array);
    Datum      *in_datums;
    bool       *in_nulls;
    int         in_count,
                count,
                i;
    JsonbInState result;

    memset(&result, 0, sizeof(JsonbInState));

    (void) pushJsonbValue(&result.parseState, WJB_BEGIN_OBJECT, NULL);

    switch (ndims)
    {
        case 0:
            goto close_object;
            break;

        case 1:
            if ((ARR_DIMS(in_array)[0]) % 2)
                ereport(ERROR,
                        (errcode(ERRCODE_ARRAY_SUBSCRIPT_ERROR),
                         errmsg("array must have even number of elements")));
            break;

        case 2:
            if ((ARR_DIMS(in_array)[1]) != 2)
                ereport(ERROR,
                        (errcode(ERRCODE_ARRAY_SUBSCRIPT_ERROR),
                         errmsg("array must have two columns")));
            break;

        default:
            ereport(ERROR,
                    (errcode(ERRCODE_ARRAY_SUBSCRIPT_ERROR),
                     errmsg("wrong number of array subscripts")));
    }

    deconstruct_array(in_array,
                      TEXTOID, -1, false, 'i',
                      &in_datums, &in_nulls, &in_count);

    count = in_count / 2;

    for (i = 0; i < count; ++i)
    {
        JsonbValue  v;
        char       *str;
        int         len;

        if (in_nulls[i * 2])
            ereport(ERROR,
                    (errcode(ERRCODE_NULL_VALUE_NOT_ALLOWED),
                     errmsg("null value not allowed for object key")));

        str = TextDatumGetCString(in_datums[i * 2]);
        len = strlen(str);

        v.type = jbvString;

        v.val.string.len = len;
        v.val.string.val = str;

        (void) pushJsonbValue(&result.parseState, WJB_KEY, &v);

        if (in_nulls[i * 2 + 1])
        {
            v.type = jbvNull;
        }
        else
        {
            str = TextDatumGetCString(in_datums[i * 2 + 1]);
            len = strlen(str);

            v.type = jbvString;

            v.val.string.len = len;
            v.val.string.val = str;
        }

        (void) pushJsonbValue(&result.parseState, WJB_VALUE, &v);
    }

    pfree(in_datums);
    pfree(in_nulls);

close_object:
    result.res = pushJsonbValue(&result.parseState, WJB_END_OBJECT, NULL);

    PG_RETURN_POINTER(JsonbValueToJsonb(result.res));
}

/*
 * SQL function jsonb_object(text[], text[])
 *
 * take separate name and value arrays of text to construct a jsonb object
 * pairwise.
 */
Datum
jsonb_object_two_arg(PG_FUNCTION_ARGS)
{
    ArrayType  *key_array = PG_GETARG_ARRAYTYPE_P(0);
    ArrayType  *val_array = PG_GETARG_ARRAYTYPE_P(1);
    int         nkdims = ARR_NDIM(key_array);
    int         nvdims = ARR_NDIM(val_array);
    Datum      *key_datums,
               *val_datums;
    bool       *key_nulls,
               *val_nulls;
    int         key_count,
                val_count,
                i;
    JsonbInState result;

    memset(&result, 0, sizeof(JsonbInState));

    (void) pushJsonbValue(&result.parseState, WJB_BEGIN_OBJECT, NULL);

    if (nkdims > 1 || nkdims != nvdims)
        ereport(ERROR,
                (errcode(ERRCODE_ARRAY_SUBSCRIPT_ERROR),
                 errmsg("wrong number of array subscripts")));

    if (nkdims == 0)
        goto close_object;

    deconstruct_array(key_array,
                      TEXTOID, -1, false, 'i',
                      &key_datums, &key_nulls, &key_count);

    deconstruct_array(val_array,
                      TEXTOID, -1, false, 'i',
                      &val_datums, &val_nulls, &val_count);

    if (key_count != val_count)
        ereport(ERROR,
                (errcode(ERRCODE_ARRAY_SUBSCRIPT_ERROR),
                 errmsg("mismatched array dimensions")));

    for (i = 0; i < key_count; ++i)
    {
        JsonbValue  v;
        char       *str;
        int         len;

        if (key_nulls[i])
            ereport(ERROR,
                    (errcode(ERRCODE_NULL_VALUE_NOT_ALLOWED),
                     errmsg("null value not allowed for object key")));

        str = TextDatumGetCString(key_datums[i]);
        len = strlen(str);

        v.type = jbvString;

        v.val.string.len = len;
        v.val.string.val = str;

        (void) pushJsonbValue(&result.parseState, WJB_KEY, &v);

        if (val_nulls[i])
        {
            v.type = jbvNull;
        }
        else
        {
            str = TextDatumGetCString(val_datums[i]);
            len = strlen(str);

            v.type = jbvString;

            v.val.string.len = len;
            v.val.string.val = str;
        }

        (void) pushJsonbValue(&result.parseState, WJB_VALUE, &v);
    }

    pfree(key_datums);
    pfree(key_nulls);
    pfree(val_datums);
    pfree(val_nulls);

close_object:
    result.res = pushJsonbValue(&result.parseState, WJB_END_OBJECT, NULL);

    PG_RETURN_POINTER(JsonbValueToJsonb(result.res));
}


/*
 * shallow clone of a parse state, suitable for use in aggregate
 * final functions that will only append to the values rather than
 * change them.
 */
static JsonbParseState *
clone_parse_state(JsonbParseState *state)
{
    JsonbParseState *result,
               *icursor,
               *ocursor;

    if (state == NULL)
        return NULL;

    result = palloc(sizeof(JsonbParseState));
    icursor = state;
    ocursor = result;
    for (;;)
    {
        ocursor->contVal = icursor->contVal;
        ocursor->size = icursor->size;
        icursor = icursor->next;
        if (icursor == NULL)
            break;
        ocursor->next = palloc(sizeof(JsonbParseState));
        ocursor = ocursor->next;
    }
    ocursor->next = NULL;

    return result;
}


/*
 * jsonb_agg aggregate function
 */
Datum
jsonb_agg_transfn(PG_FUNCTION_ARGS)
{
    MemoryContext oldcontext,
                aggcontext;
    JsonbAggState *state;
    JsonbInState elem;
    Datum       val;
    JsonbInState *result;
    bool        single_scalar = false;
    JsonbIterator *it;
    Jsonb      *jbelem;
    JsonbValue  v;
    JsonbIteratorToken type;

    if (!AggCheckCallContext(fcinfo, &aggcontext))
    {
        /* cannot be called directly because of internal-type argument */
        elog(ERROR, "jsonb_agg_transfn called in non-aggregate context");
    }

    /* set up the accumulator on the first go round */

    if (PG_ARGISNULL(0))
    {
        Oid         arg_type = get_fn_expr_argtype(fcinfo->flinfo, 1);

        if (arg_type == InvalidOid)
            ereport(ERROR,
                    (errcode(ERRCODE_INVALID_PARAMETER_VALUE),
                     errmsg("could not determine input data type")));

        oldcontext = MemoryContextSwitchTo(aggcontext);
        state = palloc(sizeof(JsonbAggState));
        result = palloc0(sizeof(JsonbInState));
        state->res = result;
        result->res = pushJsonbValue(&result->parseState,
                                     WJB_BEGIN_ARRAY, NULL);
        MemoryContextSwitchTo(oldcontext);

        jsonb_categorize_type(arg_type, &state->val_category,
                              &state->val_output_func);
    }
    else
    {
        state = (JsonbAggState *) PG_GETARG_POINTER(0);
        result = state->res;
    }

    /* turn the argument into jsonb in the normal function context */

    val = PG_ARGISNULL(1) ? (Datum) 0 : PG_GETARG_DATUM(1);

    memset(&elem, 0, sizeof(JsonbInState));

    datum_to_jsonb(val, PG_ARGISNULL(1), &elem, state->val_category,
                   state->val_output_func, false);

    jbelem = JsonbValueToJsonb(elem.res);

    /* switch to the aggregate context for accumulation operations */

    oldcontext = MemoryContextSwitchTo(aggcontext);

    it = JsonbIteratorInit(&jbelem->root);

    while ((type = JsonbIteratorNext(&it, &v, false)) != WJB_DONE)
    {
        switch (type)
        {
            case WJB_BEGIN_ARRAY:
                if (v.val.array.rawScalar)
                    single_scalar = true;
                else
                    result->res = pushJsonbValue(&result->parseState,
                                                 type, NULL);
                break;
            case WJB_END_ARRAY:
                if (!single_scalar)
                    result->res = pushJsonbValue(&result->parseState,
                                                 type, NULL);
                break;
            case WJB_BEGIN_OBJECT:
            case WJB_END_OBJECT:
                result->res = pushJsonbValue(&result->parseState,
                                             type, NULL);
                break;
            case WJB_ELEM:
            case WJB_KEY:
            case WJB_VALUE:
                if (v.type == jbvString)
                {
                    /* copy string values in the aggregate context */
                    char       *buf = palloc(v.val.string.len + 1);

                    snprintf(buf, v.val.string.len + 1, "%s", v.val.string.val);
                    v.val.string.val = buf;
                }
                else if (v.type == jbvNumeric)
                {
                    /* same for numeric */
                    v.val.numeric =
                        DatumGetNumeric(DirectFunctionCall1(numeric_uplus,
                                                            NumericGetDatum(v.val.numeric)));
                }
                result->res = pushJsonbValue(&result->parseState,
                                             type, &v);
                break;
            default:
                elog(ERROR, "unknown jsonb iterator token type");
        }
    }

    MemoryContextSwitchTo(oldcontext);

    PG_RETURN_POINTER(state);
}

Datum
jsonb_agg_finalfn(PG_FUNCTION_ARGS)
{
    JsonbAggState *arg;
    JsonbInState result;
    Jsonb      *out;

    /* cannot be called directly because of internal-type argument */
    Assert(AggCheckCallContext(fcinfo, NULL));

    if (PG_ARGISNULL(0))
        PG_RETURN_NULL();       /* returns null iff no input values */

    arg = (JsonbAggState *) PG_GETARG_POINTER(0);

    /*
     * We need to do a shallow clone of the argument in case the final
     * function is called more than once, so we avoid changing the argument. A
     * shallow clone is sufficient as we aren't going to change any of the
     * values, just add the final array end marker.
     */

    result.parseState = clone_parse_state(arg->res->parseState);

    result.res = pushJsonbValue(&result.parseState,
                                WJB_END_ARRAY, NULL);

    out = JsonbValueToJsonb(result.res);

    PG_RETURN_POINTER(out);
}

/*
 * jsonb_object_agg aggregate function
 */
Datum
jsonb_object_agg_transfn(PG_FUNCTION_ARGS)
{
    MemoryContext oldcontext,
                aggcontext;
    JsonbInState elem;
    JsonbAggState *state;
    Datum       val;
    JsonbInState *result;
    bool        single_scalar;
    JsonbIterator *it;
    Jsonb      *jbkey,
               *jbval;
    JsonbValue  v;
    JsonbIteratorToken type;

    if (!AggCheckCallContext(fcinfo, &aggcontext))
    {
        /* cannot be called directly because of internal-type argument */
        elog(ERROR, "jsonb_object_agg_transfn called in non-aggregate context");
    }

    /* set up the accumulator on the first go round */

    if (PG_ARGISNULL(0))
    {
        Oid         arg_type;

        oldcontext = MemoryContextSwitchTo(aggcontext);
        state = palloc(sizeof(JsonbAggState));
        result = palloc0(sizeof(JsonbInState));
        state->res = result;
        result->res = pushJsonbValue(&result->parseState,
                                     WJB_BEGIN_OBJECT, NULL);
        MemoryContextSwitchTo(oldcontext);

        arg_type = get_fn_expr_argtype(fcinfo->flinfo, 1);

        if (arg_type == InvalidOid)
            ereport(ERROR,
                    (errcode(ERRCODE_INVALID_PARAMETER_VALUE),
                     errmsg("could not determine input data type")));

        jsonb_categorize_type(arg_type, &state->key_category,
                              &state->key_output_func);

        arg_type = get_fn_expr_argtype(fcinfo->flinfo, 2);

        if (arg_type == InvalidOid)
            ereport(ERROR,
                    (errcode(ERRCODE_INVALID_PARAMETER_VALUE),
                     errmsg("could not determine input data type")));

        jsonb_categorize_type(arg_type, &state->val_category,
                              &state->val_output_func);
    }
    else
    {
        state = (JsonbAggState *) PG_GETARG_POINTER(0);
        result = state->res;
    }

    /* turn the argument into jsonb in the normal function context */

    if (PG_ARGISNULL(1))
        ereport(ERROR,
                (errcode(ERRCODE_INVALID_PARAMETER_VALUE),
                 errmsg("field name must not be null")));

    val = PG_GETARG_DATUM(1);

    memset(&elem, 0, sizeof(JsonbInState));

    datum_to_jsonb(val, false, &elem, state->key_category,
                   state->key_output_func, true);

    jbkey = JsonbValueToJsonb(elem.res);

    val = PG_ARGISNULL(2) ? (Datum) 0 : PG_GETARG_DATUM(2);

    memset(&elem, 0, sizeof(JsonbInState));

    datum_to_jsonb(val, PG_ARGISNULL(2), &elem, state->val_category,
                   state->val_output_func, false);

    jbval = JsonbValueToJsonb(elem.res);

    it = JsonbIteratorInit(&jbkey->root);

    /* switch to the aggregate context for accumulation operations */

    oldcontext = MemoryContextSwitchTo(aggcontext);

    /*
     * keys should be scalar, and we should have already checked for that
     * above when calling datum_to_jsonb, so we only need to look for these
     * things.
     */

    while ((type = JsonbIteratorNext(&it, &v, false)) != WJB_DONE)
    {
        switch (type)
        {
            case WJB_BEGIN_ARRAY:
                if (!v.val.array.rawScalar)
                    elog(ERROR, "unexpected structure for key");
                break;
            case WJB_ELEM:
                if (v.type == jbvString)
                {
                    /* copy string values in the aggregate context */
                    char       *buf = palloc(v.val.string.len + 1);

                    snprintf(buf, v.val.string.len + 1, "%s", v.val.string.val);
                    v.val.string.val = buf;
                }
                else
                {
                    ereport(ERROR,
                            (errcode(ERRCODE_INVALID_PARAMETER_VALUE),
                             errmsg("object keys must be strings")));
                }
                result->res = pushJsonbValue(&result->parseState,
                                             WJB_KEY, &v);
                break;
            case WJB_END_ARRAY:
                break;
            default:
                elog(ERROR, "unexpected structure for key");
                break;
        }
    }

    it = JsonbIteratorInit(&jbval->root);

    single_scalar = false;

    /*
     * values can be anything, including structured and null, so we treat them
     * as in json_agg_transfn, except that single scalars are always pushed as
     * WJB_VALUE items.
     */

    while ((type = JsonbIteratorNext(&it, &v, false)) != WJB_DONE)
    {
        switch (type)
        {
            case WJB_BEGIN_ARRAY:
                if (v.val.array.rawScalar)
                    single_scalar = true;
                else
                    result->res = pushJsonbValue(&result->parseState,
                                                 type, NULL);
                break;
            case WJB_END_ARRAY:
                if (!single_scalar)
                    result->res = pushJsonbValue(&result->parseState,
                                                 type, NULL);
                break;
            case WJB_BEGIN_OBJECT:
            case WJB_END_OBJECT:
                result->res = pushJsonbValue(&result->parseState,
                                             type, NULL);
                break;
            case WJB_ELEM:
            case WJB_KEY:
            case WJB_VALUE:
                if (v.type == jbvString)
                {
                    /* copy string values in the aggregate context */
                    char       *buf = palloc(v.val.string.len + 1);

                    snprintf(buf, v.val.string.len + 1, "%s", v.val.string.val);
                    v.val.string.val = buf;
                }
                else if (v.type == jbvNumeric)
                {
                    /* same for numeric */
                    v.val.numeric =
                        DatumGetNumeric(DirectFunctionCall1(numeric_uplus,
                                                            NumericGetDatum(v.val.numeric)));
                }
                result->res = pushJsonbValue(&result->parseState,
                                             single_scalar ? WJB_VALUE : type,
                                             &v);
                break;
            default:
                elog(ERROR, "unknown jsonb iterator token type");
        }
    }

    MemoryContextSwitchTo(oldcontext);

    PG_RETURN_POINTER(state);
}

Datum
jsonb_object_agg_finalfn(PG_FUNCTION_ARGS)
{
    JsonbAggState *arg;
    JsonbInState result;
    Jsonb      *out;

    /* cannot be called directly because of internal-type argument */
    Assert(AggCheckCallContext(fcinfo, NULL));

    if (PG_ARGISNULL(0))
        PG_RETURN_NULL();       /* returns null iff no input values */

    arg = (JsonbAggState *) PG_GETARG_POINTER(0);

    /*
     * We need to do a shallow clone of the argument's res field in case the
     * final function is called more than once, so we avoid changing the
     * aggregate state value.  A shallow clone is sufficient as we aren't
     * going to change any of the values, just add the final object end
     * marker.
     */

    result.parseState = clone_parse_state(arg->res->parseState);

    result.res = pushJsonbValue(&result.parseState,
                                WJB_END_OBJECT, NULL);

    out = JsonbValueToJsonb(result.res);

    PG_RETURN_POINTER(out);
}


/*
 * Extract scalar value from raw-scalar pseudo-array jsonb.
 */
bool
JsonbExtractScalar(JsonbContainer *jbc, JsonbValue *res)
{
    JsonbIterator *it;
    JsonbIteratorToken tok PG_USED_FOR_ASSERTS_ONLY;
    JsonbValue  tmp;

    if (!JsonContainerIsArray(jbc) || !JsonContainerIsScalar(jbc))
    {
        /* inform caller about actual type of container */
        res->type = (JsonContainerIsArray(jbc)) ? jbvArray : jbvObject;
        return false;
    }

    /*
     * A root scalar is stored as an array of one element, so we get the array
     * and then its first (and only) member.
     */
    it = JsonbIteratorInit(jbc);

    tok = JsonbIteratorNext(&it, &tmp, true);
    Assert(tok == WJB_BEGIN_ARRAY);
    Assert(tmp.val.array.nElems == 1 && tmp.val.array.rawScalar);

    tok = JsonbIteratorNext(&it, res, true);
    Assert(tok == WJB_ELEM);
    Assert(IsAJsonbScalar(res));

    tok = JsonbIteratorNext(&it, &tmp, true);
    Assert(tok == WJB_END_ARRAY);

    tok = JsonbIteratorNext(&it, &tmp, true);
    Assert(tok == WJB_DONE);

    return true;
}

/*
 * Emit correct, translatable cast error message
 */
static void
cannotCastJsonbValue(enum jbvType type, const char *sqltype)
{
    static const struct
    {
        enum jbvType type;
        const char *msg;
    }
                messages[] =
    {
        {jbvNull, gettext_noop("cannot cast jsonb null to type %s")},
        {jbvString, gettext_noop("cannot cast jsonb string to type %s")},
        {jbvNumeric, gettext_noop("cannot cast jsonb numeric to type %s")},
        {jbvBool, gettext_noop("cannot cast jsonb boolean to type %s")},
        {jbvArray, gettext_noop("cannot cast jsonb array to type %s")},
        {jbvObject, gettext_noop("cannot cast jsonb object to type %s")},
        {jbvBinary, gettext_noop("cannot cast jsonb array or object to type %s")}
    };
    int         i;

    for (i = 0; i < lengthof(messages); i++)
        if (messages[i].type == type)
            ereport(ERROR,
                    (errcode(ERRCODE_INVALID_PARAMETER_VALUE),
                     errmsg(messages[i].msg, sqltype)));

    /* should be unreachable */
    elog(ERROR, "unknown jsonb type: %d", (int) type);
}

Datum
jsonb_bool(PG_FUNCTION_ARGS)
{
    Jsonb      *in = PG_GETARG_JSONB_P(0);
    JsonbValue  v;

    if (!JsonbExtractScalar(&in->root, &v) || v.type != jbvBool)
        cannotCastJsonbValue(v.type, "boolean");

    PG_FREE_IF_COPY(in, 0);

    PG_RETURN_BOOL(v.val.boolean);
}

Datum
jsonb_numeric(PG_FUNCTION_ARGS)
{
    Jsonb      *in = PG_GETARG_JSONB_P(0);
    JsonbValue  v;
    Numeric     retValue;

    if (!JsonbExtractScalar(&in->root, &v) || v.type != jbvNumeric)
        cannotCastJsonbValue(v.type, "numeric");

    /*
     * v.val.numeric points into jsonb body, so we need to make a copy to
     * return
     */
    retValue = DatumGetNumericCopy(NumericGetDatum(v.val.numeric));

    PG_FREE_IF_COPY(in, 0);

    PG_RETURN_NUMERIC(retValue);
}

Datum
jsonb_int2(PG_FUNCTION_ARGS)
{
    Jsonb      *in = PG_GETARG_JSONB_P(0);
    JsonbValue  v;
    Datum       retValue;

    if (!JsonbExtractScalar(&in->root, &v) || v.type != jbvNumeric)
        cannotCastJsonbValue(v.type, "smallint");

    retValue = DirectFunctionCall1(numeric_int2,
                                   NumericGetDatum(v.val.numeric));

    PG_FREE_IF_COPY(in, 0);

    PG_RETURN_DATUM(retValue);
}

Datum
jsonb_int4(PG_FUNCTION_ARGS)
{
    Jsonb      *in = PG_GETARG_JSONB_P(0);
    JsonbValue  v;
    Datum       retValue;

    if (!JsonbExtractScalar(&in->root, &v) || v.type != jbvNumeric)
        cannotCastJsonbValue(v.type, "integer");

    retValue = DirectFunctionCall1(numeric_int4,
                                   NumericGetDatum(v.val.numeric));

    PG_FREE_IF_COPY(in, 0);

    PG_RETURN_DATUM(retValue);
}

Datum
jsonb_int8(PG_FUNCTION_ARGS)
{
    Jsonb      *in = PG_GETARG_JSONB_P(0);
    JsonbValue  v;
    Datum       retValue;

    if (!JsonbExtractScalar(&in->root, &v) || v.type != jbvNumeric)
        cannotCastJsonbValue(v.type, "bigint");

    retValue = DirectFunctionCall1(numeric_int8,
                                   NumericGetDatum(v.val.numeric));

    PG_FREE_IF_COPY(in, 0);

    PG_RETURN_DATUM(retValue);
}

Datum
jsonb_float4(PG_FUNCTION_ARGS)
{
    Jsonb      *in = PG_GETARG_JSONB_P(0);
    JsonbValue  v;
    Datum       retValue;

    if (!JsonbExtractScalar(&in->root, &v) || v.type != jbvNumeric)
        cannotCastJsonbValue(v.type, "real");

    retValue = DirectFunctionCall1(numeric_float4,
                                   NumericGetDatum(v.val.numeric));

    PG_FREE_IF_COPY(in, 0);

    PG_RETURN_DATUM(retValue);
}

Datum
jsonb_float8(PG_FUNCTION_ARGS)
{
    Jsonb      *in = PG_GETARG_JSONB_P(0);
    JsonbValue  v;
    Datum       retValue;

    if (!JsonbExtractScalar(&in->root, &v) || v.type != jbvNumeric)
        cannotCastJsonbValue(v.type, "double precision");

    retValue = DirectFunctionCall1(numeric_float8,
                                   NumericGetDatum(v.val.numeric));

    PG_FREE_IF_COPY(in, 0);

    PG_RETURN_DATUM(retValue);
}