execExpr.h

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/*-------------------------------------------------------------------------
 *
 * execExpr.h
 *    Low level infrastructure related to expression evaluation
 *
 *
 * Portions Copyright (c) 1996-2023, PostgreSQL Global Development Group
 * Portions Copyright (c) 1994, Regents of the University of California
 *
 * src/include/executor/execExpr.h
 *
 *-------------------------------------------------------------------------
 */
#ifndef EXEC_EXPR_H
#define EXEC_EXPR_H
 
#include "executor/nodeAgg.h"
#include "nodes/execnodes.h"
 
/* forward references to avoid circularity */
struct ExprEvalStep;
struct SubscriptingRefState;
struct ScalarArrayOpExprHashTable;
struct JsonConstructorExprState;
 
/* Bits in ExprState->flags (see also execnodes.h for public flag bits): */
/* expression's interpreter has been initialized */
#define EEO_FLAG_INTERPRETER_INITIALIZED    (1 << 1)
/* jump-threading is in use */
#define EEO_FLAG_DIRECT_THREADED            (1 << 2)
 
/* Typical API for out-of-line evaluation subroutines */
typedef void (*ExecEvalSubroutine) (ExprState *state,
                                    struct ExprEvalStep *op,
                                    ExprContext *econtext);
 
/* API for out-of-line evaluation subroutines returning bool */
typedef bool (*ExecEvalBoolSubroutine) (ExprState *state,
                                        struct ExprEvalStep *op,
                                        ExprContext *econtext);
 
/* ExprEvalSteps that cache a composite type's tupdesc need one of these */
/* (it fits in-line in some step types, otherwise allocate out-of-line) */
typedef struct ExprEvalRowtypeCache
{
    /*
     * cacheptr points to composite type's TypeCacheEntry if tupdesc_id is not
     * 0; or for an anonymous RECORD type, it points directly at the cached
     * tupdesc for the type, and tupdesc_id is 0.  (We'd use separate fields
     * if space were not at a premium.)  Initial state is cacheptr == NULL.
     */
    void       *cacheptr;
    uint64      tupdesc_id;     /* last-seen tupdesc identifier, or 0 */
} ExprEvalRowtypeCache;
 
/*
 * Discriminator for ExprEvalSteps.
 *
 * Identifies the operation to be executed and which member in the
 * ExprEvalStep->d union is valid.
 *
 * The order of entries needs to be kept in sync with the dispatch_table[]
 * array in execExprInterp.c:ExecInterpExpr().
 */
typedef enum ExprEvalOp
{
    /* entire expression has been evaluated completely, return */
    EEOP_DONE,
 
    /* apply slot_getsomeattrs on corresponding tuple slot */
    EEOP_INNER_FETCHSOME,
    EEOP_OUTER_FETCHSOME,
    EEOP_SCAN_FETCHSOME,
 
    /* compute non-system Var value */
    EEOP_INNER_VAR,
    EEOP_OUTER_VAR,
    EEOP_SCAN_VAR,
 
    /* compute system Var value */
    EEOP_INNER_SYSVAR,
    EEOP_OUTER_SYSVAR,
    EEOP_SCAN_SYSVAR,
 
    /* compute wholerow Var */
    EEOP_WHOLEROW,
 
    /*
     * Compute non-system Var value, assign it into ExprState's resultslot.
     * These are not used if a CheckVarSlotCompatibility() check would be
     * needed.
     */
    EEOP_ASSIGN_INNER_VAR,
    EEOP_ASSIGN_OUTER_VAR,
    EEOP_ASSIGN_SCAN_VAR,
 
    /* assign ExprState's resvalue/resnull to a column of its resultslot */
    EEOP_ASSIGN_TMP,
    /* ditto, applying MakeExpandedObjectReadOnly() */
    EEOP_ASSIGN_TMP_MAKE_RO,
 
    /* evaluate Const value */
    EEOP_CONST,
 
    /*
     * Evaluate function call (including OpExprs etc).  For speed, we
     * distinguish in the opcode whether the function is strict and/or
     * requires usage stats tracking.
     */
    EEOP_FUNCEXPR,
    EEOP_FUNCEXPR_STRICT,
    EEOP_FUNCEXPR_FUSAGE,
    EEOP_FUNCEXPR_STRICT_FUSAGE,
 
    /*
     * Evaluate boolean AND expression, one step per subexpression. FIRST/LAST
     * subexpressions are special-cased for performance.  Since AND always has
     * at least two subexpressions, FIRST and LAST never apply to the same
     * subexpression.
     */
    EEOP_BOOL_AND_STEP_FIRST,
    EEOP_BOOL_AND_STEP,
    EEOP_BOOL_AND_STEP_LAST,
 
    /* similarly for boolean OR expression */
    EEOP_BOOL_OR_STEP_FIRST,
    EEOP_BOOL_OR_STEP,
    EEOP_BOOL_OR_STEP_LAST,
 
    /* evaluate boolean NOT expression */
    EEOP_BOOL_NOT_STEP,
 
    /* simplified version of BOOL_AND_STEP for use by ExecQual() */
    EEOP_QUAL,
 
    /* unconditional jump to another step */
    EEOP_JUMP,
 
    /* conditional jumps based on current result value */
    EEOP_JUMP_IF_NULL,
    EEOP_JUMP_IF_NOT_NULL,
    EEOP_JUMP_IF_NOT_TRUE,
 
    /* perform NULL tests for scalar values */
    EEOP_NULLTEST_ISNULL,
    EEOP_NULLTEST_ISNOTNULL,
 
    /* perform NULL tests for row values */
    EEOP_NULLTEST_ROWISNULL,
    EEOP_NULLTEST_ROWISNOTNULL,
 
    /* evaluate a BooleanTest expression */
    EEOP_BOOLTEST_IS_TRUE,
    EEOP_BOOLTEST_IS_NOT_TRUE,
    EEOP_BOOLTEST_IS_FALSE,
    EEOP_BOOLTEST_IS_NOT_FALSE,
 
    /* evaluate PARAM_EXEC/EXTERN parameters */
    EEOP_PARAM_EXEC,
    EEOP_PARAM_EXTERN,
    EEOP_PARAM_CALLBACK,
 
    /* return CaseTestExpr value */
    EEOP_CASE_TESTVAL,
 
    /* apply MakeExpandedObjectReadOnly() to target value */
    EEOP_MAKE_READONLY,
 
    /* evaluate assorted special-purpose expression types */
    EEOP_IOCOERCE,
    EEOP_DISTINCT,
    EEOP_NOT_DISTINCT,
    EEOP_NULLIF,
    EEOP_SQLVALUEFUNCTION,
    EEOP_CURRENTOFEXPR,
    EEOP_NEXTVALUEEXPR,
    EEOP_ARRAYEXPR,
    EEOP_ARRAYCOERCE,
    EEOP_ROW,
 
    /*
     * Compare two individual elements of each of two compared ROW()
     * expressions.  Skip to ROWCOMPARE_FINAL if elements are not equal.
     */
    EEOP_ROWCOMPARE_STEP,
 
    /* evaluate boolean value based on previous ROWCOMPARE_STEP operations */
    EEOP_ROWCOMPARE_FINAL,
 
    /* evaluate GREATEST() or LEAST() */
    EEOP_MINMAX,
 
    /* evaluate FieldSelect expression */
    EEOP_FIELDSELECT,
 
    /*
     * Deform tuple before evaluating new values for individual fields in a
     * FieldStore expression.
     */
    EEOP_FIELDSTORE_DEFORM,
 
    /*
     * Form the new tuple for a FieldStore expression.  Individual fields will
     * have been evaluated into columns of the tuple deformed by the preceding
     * DEFORM step.
     */
    EEOP_FIELDSTORE_FORM,
 
    /* Process container subscripts; possibly short-circuit result to NULL */
    EEOP_SBSREF_SUBSCRIPTS,
 
    /*
     * Compute old container element/slice when a SubscriptingRef assignment
     * expression contains SubscriptingRef/FieldStore subexpressions. Value is
     * accessed using the CaseTest mechanism.
     */
    EEOP_SBSREF_OLD,
 
    /* compute new value for SubscriptingRef assignment expression */
    EEOP_SBSREF_ASSIGN,
 
    /* compute element/slice for SubscriptingRef fetch expression */
    EEOP_SBSREF_FETCH,
 
    /* evaluate value for CoerceToDomainValue */
    EEOP_DOMAIN_TESTVAL,
 
    /* evaluate a domain's NOT NULL constraint */
    EEOP_DOMAIN_NOTNULL,
 
    /* evaluate a single domain CHECK constraint */
    EEOP_DOMAIN_CHECK,
 
    /* evaluate assorted special-purpose expression types */
    EEOP_CONVERT_ROWTYPE,
    EEOP_SCALARARRAYOP,
    EEOP_HASHED_SCALARARRAYOP,
    EEOP_XMLEXPR,
    EEOP_JSON_CONSTRUCTOR,
    EEOP_IS_JSON,
    EEOP_AGGREF,
    EEOP_GROUPING_FUNC,
    EEOP_WINDOW_FUNC,
    EEOP_SUBPLAN,
 
    /* aggregation related nodes */
    EEOP_AGG_STRICT_DESERIALIZE,
    EEOP_AGG_DESERIALIZE,
    EEOP_AGG_STRICT_INPUT_CHECK_ARGS,
    EEOP_AGG_STRICT_INPUT_CHECK_NULLS,
    EEOP_AGG_PLAIN_PERGROUP_NULLCHECK,
    EEOP_AGG_PLAIN_TRANS_INIT_STRICT_BYVAL,
    EEOP_AGG_PLAIN_TRANS_STRICT_BYVAL,
    EEOP_AGG_PLAIN_TRANS_BYVAL,
    EEOP_AGG_PLAIN_TRANS_INIT_STRICT_BYREF,
    EEOP_AGG_PLAIN_TRANS_STRICT_BYREF,
    EEOP_AGG_PLAIN_TRANS_BYREF,
    EEOP_AGG_PRESORTED_DISTINCT_SINGLE,
    EEOP_AGG_PRESORTED_DISTINCT_MULTI,
    EEOP_AGG_ORDERED_TRANS_DATUM,
    EEOP_AGG_ORDERED_TRANS_TUPLE,
 
    /* non-existent operation, used e.g. to check array lengths */
    EEOP_LAST
} ExprEvalOp;
 
 
typedef struct ExprEvalStep
{
    /*
     * Instruction to be executed.  During instruction preparation this is an
     * enum ExprEvalOp, but later it can be changed to some other type, e.g. a
     * pointer for computed goto (that's why it's an intptr_t).
     */
    intptr_t    opcode;
 
    /* where to store the result of this step */
    Datum      *resvalue;
    bool       *resnull;
 
    /*
     * Inline data for the operation.  Inline data is faster to access, but
     * also bloats the size of all instructions.  The union should be kept to
     * no more than 40 bytes on 64-bit systems (so that the entire struct is
     * no more than 64 bytes, a single cacheline on common systems).
     */
    union
    {
        /* for EEOP_INNER/OUTER/SCAN_FETCHSOME */
        struct
        {
            /* attribute number up to which to fetch (inclusive) */
            int         last_var;
            /* will the type of slot be the same for every invocation */
            bool        fixed;
            /* tuple descriptor, if known */
            TupleDesc   known_desc;
            /* type of slot, can only be relied upon if fixed is set */
            const TupleTableSlotOps *kind;
        }           fetch;
 
        /* for EEOP_INNER/OUTER/SCAN_[SYS]VAR[_FIRST] */
        struct
        {
            /* attnum is attr number - 1 for regular VAR ... */
            /* but it's just the normal (negative) attr number for SYSVAR */
            int         attnum;
            Oid         vartype;    /* type OID of variable */
        }           var;
 
        /* for EEOP_WHOLEROW */
        struct
        {
            Var        *var;    /* original Var node in plan tree */
            bool        first;  /* first time through, need to initialize? */
            bool        slow;   /* need runtime check for nulls? */
            TupleDesc   tupdesc;    /* descriptor for resulting tuples */
            JunkFilter *junkFilter; /* JunkFilter to remove resjunk cols */
        }           wholerow;
 
        /* for EEOP_ASSIGN_*_VAR */
        struct
        {
            /* target index in ExprState->resultslot->tts_values/nulls */
            int         resultnum;
            /* source attribute number - 1 */
            int         attnum;
        }           assign_var;
 
        /* for EEOP_ASSIGN_TMP[_MAKE_RO] */
        struct
        {
            /* target index in ExprState->resultslot->tts_values/nulls */
            int         resultnum;
        }           assign_tmp;
 
        /* for EEOP_CONST */
        struct
        {
            /* constant's value */
            Datum       value;
            bool        isnull;
        }           constval;
 
        /* for EEOP_FUNCEXPR_* / NULLIF / DISTINCT */
        struct
        {
            FmgrInfo   *finfo;  /* function's lookup data */
            FunctionCallInfo fcinfo_data;   /* arguments etc */
            /* faster to access without additional indirection: */
            PGFunction  fn_addr;    /* actual call address */
            int         nargs;  /* number of arguments */
        }           func;
 
        /* for EEOP_BOOL_*_STEP */
        struct
        {
            bool       *anynull;    /* track if any input was NULL */
            int         jumpdone;   /* jump here if result determined */
        }           boolexpr;
 
        /* for EEOP_QUAL */
        struct
        {
            int         jumpdone;   /* jump here on false or null */
        }           qualexpr;
 
        /* for EEOP_JUMP[_CONDITION] */
        struct
        {
            int         jumpdone;   /* target instruction's index */
        }           jump;
 
        /* for EEOP_NULLTEST_ROWIS[NOT]NULL */
        struct
        {
            /* cached descriptor for composite type - filled at runtime */
            ExprEvalRowtypeCache rowcache;
        }           nulltest_row;
 
        /* for EEOP_PARAM_EXEC/EXTERN */
        struct
        {
            int         paramid;    /* numeric ID for parameter */
            Oid         paramtype;  /* OID of parameter's datatype */
        }           param;
 
        /* for EEOP_PARAM_CALLBACK */
        struct
        {
            ExecEvalSubroutine paramfunc;   /* add-on evaluation subroutine */
            void       *paramarg;   /* private data for same */
            int         paramid;    /* numeric ID for parameter */
            Oid         paramtype;  /* OID of parameter's datatype */
        }           cparam;
 
        /* for EEOP_CASE_TESTVAL/DOMAIN_TESTVAL */
        struct
        {
            Datum      *value;  /* value to return */
            bool       *isnull;
        }           casetest;
 
        /* for EEOP_MAKE_READONLY */
        struct
        {
            Datum      *value;  /* value to coerce to read-only */
            bool       *isnull;
        }           make_readonly;
 
        /* for EEOP_IOCOERCE */
        struct
        {
            /* lookup and call info for source type's output function */
            FmgrInfo   *finfo_out;
            FunctionCallInfo fcinfo_data_out;
            /* lookup and call info for result type's input function */
            FmgrInfo   *finfo_in;
            FunctionCallInfo fcinfo_data_in;
        }           iocoerce;
 
        /* for EEOP_SQLVALUEFUNCTION */
        struct
        {
            SQLValueFunction *svf;
        }           sqlvaluefunction;
 
        /* for EEOP_NEXTVALUEEXPR */
        struct
        {
            Oid         seqid;
            Oid         seqtypid;
        }           nextvalueexpr;
 
        /* for EEOP_ARRAYEXPR */
        struct
        {
            Datum      *elemvalues; /* element values get stored here */
            bool       *elemnulls;
            int         nelems; /* length of the above arrays */
            Oid         elemtype;   /* array element type */
            int16       elemlength; /* typlen of the array element type */
            bool        elembyval;  /* is the element type pass-by-value? */
            char        elemalign;  /* typalign of the element type */
            bool        multidims;  /* is array expression multi-D? */
        }           arrayexpr;
 
        /* for EEOP_ARRAYCOERCE */
        struct
        {
            ExprState  *elemexprstate;  /* null if no per-element work */
            Oid         resultelemtype; /* element type of result array */
            struct ArrayMapState *amstate;  /* workspace for array_map */
        }           arraycoerce;
 
        /* for EEOP_ROW */
        struct
        {
            TupleDesc   tupdesc;    /* descriptor for result tuples */
            /* workspace for the values constituting the row: */
            Datum      *elemvalues;
            bool       *elemnulls;
        }           row;
 
        /* for EEOP_ROWCOMPARE_STEP */
        struct
        {
            /* lookup and call data for column comparison function */
            FmgrInfo   *finfo;
            FunctionCallInfo fcinfo_data;
            PGFunction  fn_addr;
            /* target for comparison resulting in NULL */
            int         jumpnull;
            /* target for comparison yielding inequality */
            int         jumpdone;
        }           rowcompare_step;
 
        /* for EEOP_ROWCOMPARE_FINAL */
        struct
        {
            RowCompareType rctype;
        }           rowcompare_final;
 
        /* for EEOP_MINMAX */
        struct
        {
            /* workspace for argument values */
            Datum      *values;
            bool       *nulls;
            int         nelems;
            /* is it GREATEST or LEAST? */
            MinMaxOp    op;
            /* lookup and call data for comparison function */
            FmgrInfo   *finfo;
            FunctionCallInfo fcinfo_data;
        }           minmax;
 
        /* for EEOP_FIELDSELECT */
        struct
        {
            AttrNumber  fieldnum;   /* field number to extract */
            Oid         resulttype; /* field's type */
            /* cached descriptor for composite type - filled at runtime */
            ExprEvalRowtypeCache rowcache;
        }           fieldselect;
 
        /* for EEOP_FIELDSTORE_DEFORM / FIELDSTORE_FORM */
        struct
        {
            /* original expression node */
            FieldStore *fstore;
 
            /* cached descriptor for composite type - filled at runtime */
            /* note that a DEFORM and FORM pair share the same cache */
            ExprEvalRowtypeCache *rowcache;
 
            /* workspace for column values */
            Datum      *values;
            bool       *nulls;
            int         ncolumns;
        }           fieldstore;
 
        /* for EEOP_SBSREF_SUBSCRIPTS */
        struct
        {
            ExecEvalBoolSubroutine subscriptfunc;   /* evaluation subroutine */
            /* too big to have inline */
            struct SubscriptingRefState *state;
            int         jumpdone;   /* jump here on null */
        }           sbsref_subscript;
 
        /* for EEOP_SBSREF_OLD / ASSIGN / FETCH */
        struct
        {
            ExecEvalSubroutine subscriptfunc;   /* evaluation subroutine */
            /* too big to have inline */
            struct SubscriptingRefState *state;
        }           sbsref;
 
        /* for EEOP_DOMAIN_NOTNULL / DOMAIN_CHECK */
        struct
        {
            /* name of constraint */
            char       *constraintname;
            /* where the result of a CHECK constraint will be stored */
            Datum      *checkvalue;
            bool       *checknull;
            /* OID of domain type */
            Oid         resulttype;
        }           domaincheck;
 
        /* for EEOP_CONVERT_ROWTYPE */
        struct
        {
            Oid         inputtype;  /* input composite type */
            Oid         outputtype; /* output composite type */
            /* these three fields are filled at runtime: */
            ExprEvalRowtypeCache *incache;  /* cache for input type */
            ExprEvalRowtypeCache *outcache; /* cache for output type */
            TupleConversionMap *map;    /* column mapping */
        }           convert_rowtype;
 
        /* for EEOP_SCALARARRAYOP */
        struct
        {
            /* element_type/typlen/typbyval/typalign are filled at runtime */
            Oid         element_type;   /* InvalidOid if not yet filled */
            bool        useOr;  /* use OR or AND semantics? */
            int16       typlen; /* array element type storage info */
            bool        typbyval;
            char        typalign;
            FmgrInfo   *finfo;  /* function's lookup data */
            FunctionCallInfo fcinfo_data;   /* arguments etc */
            /* faster to access without additional indirection: */
            PGFunction  fn_addr;    /* actual call address */
        }           scalararrayop;
 
        /* for EEOP_HASHED_SCALARARRAYOP */
        struct
        {
            bool        has_nulls;
            bool        inclause;   /* true for IN and false for NOT IN */
            struct ScalarArrayOpExprHashTable *elements_tab;
            FmgrInfo   *finfo;  /* function's lookup data */
            FunctionCallInfo fcinfo_data;   /* arguments etc */
            ScalarArrayOpExpr *saop;
        }           hashedscalararrayop;
 
        /* for EEOP_XMLEXPR */
        struct
        {
            XmlExpr    *xexpr;  /* original expression node */
            /* workspace for evaluating named args, if any */
            Datum      *named_argvalue;
            bool       *named_argnull;
            /* workspace for evaluating unnamed args, if any */
            Datum      *argvalue;
            bool       *argnull;
        }           xmlexpr;
 
        /* for EEOP_JSON_CONSTRUCTOR */
        struct
        {
            struct JsonConstructorExprState *jcstate;
        }           json_constructor;
 
        /* for EEOP_AGGREF */
        struct
        {
            int         aggno;
        }           aggref;
 
        /* for EEOP_GROUPING_FUNC */
        struct
        {
            List       *clauses;    /* integer list of column numbers */
        }           grouping_func;
 
        /* for EEOP_WINDOW_FUNC */
        struct
        {
            /* out-of-line state, modified by nodeWindowAgg.c */
            WindowFuncExprState *wfstate;
        }           window_func;
 
        /* for EEOP_SUBPLAN */
        struct
        {
            /* out-of-line state, created by nodeSubplan.c */
            SubPlanState *sstate;
        }           subplan;
 
        /* for EEOP_AGG_*DESERIALIZE */
        struct
        {
            FunctionCallInfo fcinfo_data;
            int         jumpnull;
        }           agg_deserialize;
 
        /* for EEOP_AGG_STRICT_INPUT_CHECK_NULLS / STRICT_INPUT_CHECK_ARGS */
        struct
        {
            /*
             * For EEOP_AGG_STRICT_INPUT_CHECK_ARGS args contains pointers to
             * the NullableDatums that need to be checked for NULLs.
             *
             * For EEOP_AGG_STRICT_INPUT_CHECK_NULLS nulls contains pointers
             * to booleans that need to be checked for NULLs.
             *
             * Both cases currently need to exist because sometimes the
             * to-be-checked nulls are in TupleTableSlot.isnull array, and
             * sometimes in FunctionCallInfoBaseData.args[i].isnull.
             */
            NullableDatum *args;
            bool       *nulls;
            int         nargs;
            int         jumpnull;
        }           agg_strict_input_check;
 
        /* for EEOP_AGG_PLAIN_PERGROUP_NULLCHECK */
        struct
        {
            int         setoff;
            int         jumpnull;
        }           agg_plain_pergroup_nullcheck;
 
        /* for EEOP_AGG_PRESORTED_DISTINCT_{SINGLE,MULTI} */
        struct
        {
            AggStatePerTrans pertrans;
            ExprContext *aggcontext;
            int         jumpdistinct;
        }           agg_presorted_distinctcheck;
 
        /* for EEOP_AGG_PLAIN_TRANS_[INIT_][STRICT_]{BYVAL,BYREF} */
        /* for EEOP_AGG_ORDERED_TRANS_{DATUM,TUPLE} */
        struct
        {
            AggStatePerTrans pertrans;
            ExprContext *aggcontext;
            int         setno;
            int         transno;
            int         setoff;
        }           agg_trans;
 
        /* for EEOP_IS_JSON */
        struct
        {
            JsonIsPredicate *pred;  /* original expression node */
        }           is_json;
 
    }           d;
} ExprEvalStep;
 
/* Enforce the size rule given in the comment above */
StaticAssertDecl(sizeof(ExprEvalStep) <= 64,
                 "size of ExprEvalStep exceeds 64 bytes");
 
 
/* Non-inline data for container operations */
typedef struct SubscriptingRefState
{
    bool        isassignment;   /* is it assignment, or just fetch? */
 
    /* workspace for type-specific subscripting code */
    void       *workspace;
 
    /* numupper and upperprovided[] are filled at expression compile time */
    /* at runtime, subscripts are computed in upperindex[]/upperindexnull[] */
    int         numupper;
    bool       *upperprovided;  /* indicates if this position is supplied */
    Datum      *upperindex;
    bool       *upperindexnull;
 
    /* similarly for lower indexes, if any */
    int         numlower;
    bool       *lowerprovided;
    Datum      *lowerindex;
    bool       *lowerindexnull;
 
    /* for assignment, new value to assign is evaluated into here */
    Datum       replacevalue;
    bool        replacenull;
 
    /* if we have a nested assignment, sbs_fetch_old puts old value here */
    Datum       prevvalue;
    bool        prevnull;
} SubscriptingRefState;
 
/* Execution step methods used for SubscriptingRef */
typedef struct SubscriptExecSteps
{
    /* See nodes/subscripting.h for more detail about these */
    ExecEvalBoolSubroutine sbs_check_subscripts;    /* process subscripts */
    ExecEvalSubroutine sbs_fetch;   /* fetch an element */
    ExecEvalSubroutine sbs_assign;  /* assign to an element */
    ExecEvalSubroutine sbs_fetch_old;   /* fetch old value for assignment */
} SubscriptExecSteps;
 
/* EEOP_JSON_CONSTRUCTOR state, too big to inline */
typedef struct JsonConstructorExprState
{
    JsonConstructorExpr *constructor;
    Datum      *arg_values;
    bool       *arg_nulls;
    Oid        *arg_types;
    struct
    {
        int         category;
        Oid         outfuncid;
    }          *arg_type_cache; /* cache for datum_to_json[b]() */
    int         nargs;
} JsonConstructorExprState;
 
 
/* functions in execExpr.c */
extern void ExprEvalPushStep(ExprState *es, const ExprEvalStep *s);
 
/* functions in execExprInterp.c */
extern void ExecReadyInterpretedExpr(ExprState *state);
extern ExprEvalOp ExecEvalStepOp(ExprState *state, ExprEvalStep *op);
 
extern Datum ExecInterpExprStillValid(ExprState *state, ExprContext *econtext, bool *isNull);
extern void CheckExprStillValid(ExprState *state, ExprContext *econtext);
 
/*
 * Non fast-path execution functions. These are externs instead of statics in
 * execExprInterp.c, because that allows them to be used by other methods of
 * expression evaluation, reducing code duplication.
 */
extern void ExecEvalFuncExprFusage(ExprState *state, ExprEvalStep *op,
                                   ExprContext *econtext);
extern void ExecEvalFuncExprStrictFusage(ExprState *state, ExprEvalStep *op,
                                         ExprContext *econtext);
extern void ExecEvalParamExec(ExprState *state, ExprEvalStep *op,
                              ExprContext *econtext);
extern void ExecEvalParamExtern(ExprState *state, ExprEvalStep *op,
                                ExprContext *econtext);
extern void ExecEvalSQLValueFunction(ExprState *state, ExprEvalStep *op);
extern void ExecEvalCurrentOfExpr(ExprState *state, ExprEvalStep *op);
extern void ExecEvalNextValueExpr(ExprState *state, ExprEvalStep *op);
extern void ExecEvalRowNull(ExprState *state, ExprEvalStep *op,
                            ExprContext *econtext);
extern void ExecEvalRowNotNull(ExprState *state, ExprEvalStep *op,
                               ExprContext *econtext);
extern void ExecEvalArrayExpr(ExprState *state, ExprEvalStep *op);
extern void ExecEvalArrayCoerce(ExprState *state, ExprEvalStep *op,
                                ExprContext *econtext);
extern void ExecEvalRow(ExprState *state, ExprEvalStep *op);
extern void ExecEvalMinMax(ExprState *state, ExprEvalStep *op);
extern void ExecEvalFieldSelect(ExprState *state, ExprEvalStep *op,
                                ExprContext *econtext);
extern void ExecEvalFieldStoreDeForm(ExprState *state, ExprEvalStep *op,
                                     ExprContext *econtext);
extern void ExecEvalFieldStoreForm(ExprState *state, ExprEvalStep *op,
                                   ExprContext *econtext);
extern void ExecEvalConvertRowtype(ExprState *state, ExprEvalStep *op,
                                   ExprContext *econtext);
extern void ExecEvalScalarArrayOp(ExprState *state, ExprEvalStep *op);
extern void ExecEvalHashedScalarArrayOp(ExprState *state, ExprEvalStep *op,
                                        ExprContext *econtext);
extern void ExecEvalConstraintNotNull(ExprState *state, ExprEvalStep *op);
extern void ExecEvalConstraintCheck(ExprState *state, ExprEvalStep *op);
extern void ExecEvalXmlExpr(ExprState *state, ExprEvalStep *op);
extern void ExecEvalJsonConstructor(ExprState *state, ExprEvalStep *op,
                                    ExprContext *econtext);
extern void ExecEvalJsonIsPredicate(ExprState *state, ExprEvalStep *op);
extern void ExecEvalGroupingFunc(ExprState *state, ExprEvalStep *op);
extern void ExecEvalSubPlan(ExprState *state, ExprEvalStep *op,
                            ExprContext *econtext);
extern void ExecEvalWholeRowVar(ExprState *state, ExprEvalStep *op,
                                ExprContext *econtext);
extern void ExecEvalSysVar(ExprState *state, ExprEvalStep *op,
                           ExprContext *econtext, TupleTableSlot *slot);
 
extern void ExecAggInitGroup(AggState *aggstate, AggStatePerTrans pertrans, AggStatePerGroup pergroup,
                             ExprContext *aggcontext);
extern Datum ExecAggCopyTransValue(AggState *aggstate, AggStatePerTrans pertrans,
                                   Datum newValue, bool newValueIsNull,
                                   Datum oldValue, bool oldValueIsNull);
extern bool ExecEvalPreOrderedDistinctSingle(AggState *aggstate,
                                             AggStatePerTrans pertrans);
extern bool ExecEvalPreOrderedDistinctMulti(AggState *aggstate,
                                            AggStatePerTrans pertrans);
extern void ExecEvalAggOrderedTransDatum(ExprState *state, ExprEvalStep *op,
                                         ExprContext *econtext);
extern void ExecEvalAggOrderedTransTuple(ExprState *state, ExprEvalStep *op,
                                         ExprContext *econtext);
 
#endif                          /* EXEC_EXPR_H */