jsonpath.h

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/*-------------------------------------------------------------------------
 *
 * jsonpath.h
 *  Definitions for jsonpath datatype
 *
 * Copyright (c) 2019-2020, PostgreSQL Global Development Group
 *
 * IDENTIFICATION
 *  src/include/utils/jsonpath.h
 *
 *-------------------------------------------------------------------------
 */

#ifndef JSONPATH_H
#define JSONPATH_H

#include "fmgr.h"
#include "nodes/pg_list.h"
#include "utils/jsonb.h"

typedef struct
{
    int32       vl_len_;        /* varlena header (do not touch directly!) */
    uint32      header;         /* version and flags (see below) */
    char        data[FLEXIBLE_ARRAY_MEMBER];
} JsonPath;

#define JSONPATH_VERSION    (0x01)
#define JSONPATH_LAX        (0x80000000)
#define JSONPATH_HDRSZ      (offsetof(JsonPath, data))

#define DatumGetJsonPathP(d)            ((JsonPath *) DatumGetPointer(PG_DETOAST_DATUM(d)))
#define DatumGetJsonPathPCopy(d)        ((JsonPath *) DatumGetPointer(PG_DETOAST_DATUM_COPY(d)))
#define PG_GETARG_JSONPATH_P(x)         DatumGetJsonPathP(PG_GETARG_DATUM(x))
#define PG_GETARG_JSONPATH_P_COPY(x)    DatumGetJsonPathPCopy(PG_GETARG_DATUM(x))
#define PG_RETURN_JSONPATH_P(p)         PG_RETURN_POINTER(p)

#define jspIsScalar(type) ((type) >= jpiNull && (type) <= jpiBool)

/*
 * All node's type of jsonpath expression
 */
typedef enum JsonPathItemType
{
    jpiNull = jbvNull,          /* NULL literal */
    jpiString = jbvString,      /* string literal */
    jpiNumeric = jbvNumeric,    /* numeric literal */
    jpiBool = jbvBool,          /* boolean literal: TRUE or FALSE */
    jpiAnd,                     /* predicate && predicate */
    jpiOr,                      /* predicate || predicate */
    jpiNot,                     /* ! predicate */
    jpiIsUnknown,               /* (predicate) IS UNKNOWN */
    jpiEqual,                   /* expr == expr */
    jpiNotEqual,                /* expr != expr */
    jpiLess,                    /* expr < expr */
    jpiGreater,                 /* expr > expr */
    jpiLessOrEqual,             /* expr <= expr */
    jpiGreaterOrEqual,          /* expr >= expr */
    jpiAdd,                     /* expr + expr */
    jpiSub,                     /* expr - expr */
    jpiMul,                     /* expr * expr */
    jpiDiv,                     /* expr / expr */
    jpiMod,                     /* expr % expr */
    jpiPlus,                    /* + expr */
    jpiMinus,                   /* - expr */
    jpiAnyArray,                /* [*] */
    jpiAnyKey,                  /* .* */
    jpiIndexArray,              /* [subscript, ...] */
    jpiAny,                     /* .** */
    jpiKey,                     /* .key */
    jpiCurrent,                 /* @ */
    jpiRoot,                    /* $ */
    jpiVariable,                /* $variable */
    jpiFilter,                  /* ? (predicate) */
    jpiExists,                  /* EXISTS (expr) predicate */
    jpiType,                    /* .type() item method */
    jpiSize,                    /* .size() item method */
    jpiAbs,                     /* .abs() item method */
    jpiFloor,                   /* .floor() item method */
    jpiCeiling,                 /* .ceiling() item method */
    jpiDouble,                  /* .double() item method */
    jpiDatetime,                /* .datetime() item method */
    jpiKeyValue,                /* .keyvalue() item method */
    jpiSubscript,               /* array subscript: 'expr' or 'expr TO expr' */
    jpiLast,                    /* LAST array subscript */
    jpiStartsWith,              /* STARTS WITH predicate */
    jpiLikeRegex,               /* LIKE_REGEX predicate */
} JsonPathItemType;

/* XQuery regex mode flags for LIKE_REGEX predicate */
#define JSP_REGEX_ICASE     0x01    /* i flag, case insensitive */
#define JSP_REGEX_DOTALL    0x02    /* s flag, dot matches newline */
#define JSP_REGEX_MLINE     0x04    /* m flag, ^/$ match at newlines */
#define JSP_REGEX_WSPACE    0x08    /* x flag, ignore whitespace in pattern */
#define JSP_REGEX_QUOTE     0x10    /* q flag, no special characters */

/*
 * Support functions to parse/construct binary value.
 * Unlike many other representation of expression the first/main
 * node is not an operation but left operand of expression. That
 * allows to implement cheap follow-path descending in jsonb
 * structure and then execute operator with right operand
 */

typedef struct JsonPathItem
{
    JsonPathItemType type;

    /* position form base to next node */
    int32       nextPos;

    /*
     * pointer into JsonPath value to current node, all positions of current
     * are relative to this base
     */
    char       *base;

    union
    {
        /* classic operator with two operands: and, or etc */
        struct
        {
            int32       left;
            int32       right;
        }           args;

        /* any unary operation */
        int32       arg;

        /* storage for jpiIndexArray: indexes of array */
        struct
        {
            int32       nelems;
            struct
            {
                int32       from;
                int32       to;
            }          *elems;
        }           array;

        /* jpiAny: levels */
        struct
        {
            uint32      first;
            uint32      last;
        }           anybounds;

        struct
        {
            char       *data;   /* for bool, numeric and string/key */
            int32       datalen;    /* filled only for string/key */
        }           value;

        struct
        {
            int32       expr;
            char       *pattern;
            int32       patternlen;
            uint32      flags;
        }           like_regex;
    }           content;
} JsonPathItem;

#define jspHasNext(jsp) ((jsp)->nextPos > 0)

extern void jspInit(JsonPathItem *v, JsonPath *js);
extern void jspInitByBuffer(JsonPathItem *v, char *base, int32 pos);
extern bool jspGetNext(JsonPathItem *v, JsonPathItem *a);
extern void jspGetArg(JsonPathItem *v, JsonPathItem *a);
extern void jspGetLeftArg(JsonPathItem *v, JsonPathItem *a);
extern void jspGetRightArg(JsonPathItem *v, JsonPathItem *a);
extern Numeric jspGetNumeric(JsonPathItem *v);
extern bool jspGetBool(JsonPathItem *v);
extern char *jspGetString(JsonPathItem *v, int32 *len);
extern bool jspGetArraySubscript(JsonPathItem *v, JsonPathItem *from,
                                 JsonPathItem *to, int i);

extern const char *jspOperationName(JsonPathItemType type);

/*
 * Parsing support data structures.
 */

typedef struct JsonPathParseItem JsonPathParseItem;

struct JsonPathParseItem
{
    JsonPathItemType type;
    JsonPathParseItem *next;    /* next in path */

    union
    {

        /* classic operator with two operands: and, or etc */
        struct
        {
            JsonPathParseItem *left;
            JsonPathParseItem *right;
        }           args;

        /* any unary operation */
        JsonPathParseItem *arg;

        /* storage for jpiIndexArray: indexes of array */
        struct
        {
            int         nelems;
            struct
            {
                JsonPathParseItem *from;
                JsonPathParseItem *to;
            }          *elems;
        }           array;

        /* jpiAny: levels */
        struct
        {
            uint32      first;
            uint32      last;
        }           anybounds;

        struct
        {
            JsonPathParseItem *expr;
            char       *pattern;    /* could not be not null-terminated */
            uint32      patternlen;
            uint32      flags;
        }           like_regex;

        /* scalars */
        Numeric numeric;
        bool        boolean;
        struct
        {
            uint32      len;
            char       *val;    /* could not be not null-terminated */
        }           string;
    }           value;
};

typedef struct JsonPathParseResult
{
    JsonPathParseItem *expr;
    bool        lax;
} JsonPathParseResult;

extern JsonPathParseResult *parsejsonpath(const char *str, int len);

extern int  jspConvertRegexFlags(uint32 xflags);

#endif