nodes.h

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/*-------------------------------------------------------------------------
 *
 * nodes.h
 *    Definitions for tagged nodes.
 *
 *
 * Portions Copyright (c) 1996-2026, PostgreSQL Global Development Group
 * Portions Copyright (c) 1994, Regents of the University of California
 *
 * src/include/nodes/nodes.h
 *
 *-------------------------------------------------------------------------
 */
#ifndef NODES_H
#define NODES_H
 
/*
 * The first field of every node is NodeTag. Each node created (with makeNode)
 * will have one of the following tags as the value of its first field.
 *
 * Note that inserting or deleting node types changes the numbers of other
 * node types later in the list.  This is no problem during development, since
 * the node numbers are never stored on disk.  But don't do it in a released
 * branch, because that would represent an ABI break for extensions.
 */
typedef enum NodeTag
{
    T_Invalid = 0,
 
#include "nodes/nodetags.h"
} NodeTag;
 
/*
 * pg_node_attr() - Used in node definitions to set extra information for
 * gen_node_support.pl
 *
 * Attributes can be attached to a node as a whole (place the attribute
 * specification on the first line after the struct's opening brace)
 * or to a specific field (place it at the end of that field's line).  The
 * argument is a comma-separated list of attributes.  Unrecognized attributes
 * cause an error.
 *
 * Valid node attributes:
 *
 * - abstract: Abstract types are types that cannot be instantiated but that
 *   can be supertypes of other types.  We track their fields, so that
 *   subtypes can use them, but we don't emit a node tag, so you can't
 *   instantiate them.
 *
 * - custom_copy_equal: Has custom implementations in copyfuncs.c and
 *   equalfuncs.c.
 *
 * - custom_read_write: Has custom implementations in outfuncs.c and
 *   readfuncs.c.
 *
 * - custom_query_jumble: Has custom implementation in queryjumblefuncs.c.
 *   Also available as a node field attribute.
 *
 * - no_copy: Does not support copyObject() at all.
 *
 * - no_equal: Does not support equal() at all.
 *
 * - no_copy_equal: Shorthand for both no_copy and no_equal.
 *
 * - no_query_jumble: Does not support JumbleQuery() at all.
 *
 * - no_read: Does not support nodeRead() at all.
 *
 * - nodetag_only: Does not support copyObject(), equal(), jumbleQuery()
 *   outNode() or nodeRead().
 *
 * - special_read_write: Has special treatment in outNode() and nodeRead().
 *
 * - nodetag_number(VALUE): assign the specified nodetag number instead of
 *   an auto-generated number.  Typically this would only be used in stable
 *   branches, to give a newly-added node type a number without breaking ABI
 *   by changing the numbers of existing node types.
 *
 * Node types can be supertypes of other types whether or not they are marked
 * abstract: if a node struct appears as the first field of another struct
 * type, then it is the supertype of that type.  The no_copy, no_equal,
 * no_query_jumble and no_read node attributes are automatically inherited
 * from the supertype.  (Notice that nodetag_only does not inherit, so it's
 * not quite equivalent to a combination of other attributes.)
 *
 * Valid node field attributes:
 *
 * - array_size(OTHERFIELD): This field is a dynamically allocated array with
 *   size indicated by the mentioned other field.  The other field is either a
 *   scalar or a list, in which case the length of the list is used.
 *
 * - copy_as(VALUE): In copyObject(), replace the field's value with VALUE.
 *
 * - copy_as_scalar: In copyObject(), copy the field as a scalar value
 *   (e.g. a pointer) even if it is a node-type pointer.
 *
 * - equal_as_scalar: In equal(), compare the field as a scalar value
 *   even if it is a node-type pointer.
 *
 * - equal_ignore: Ignore the field for equality.
 *
 * - equal_ignore_if_zero: Ignore the field for equality if it is zero.
 *   (Otherwise, compare normally.)
 *
 * - custom_query_jumble: Has custom implementation in queryjumblefuncs.c
 *   for the field of a node.  Also available as a node attribute.
 *
 * - query_jumble_ignore: Ignore the field for query jumbling.
 *
 * - query_jumble_squash: Squash multiple values during query jumbling.
 *
 * - query_jumble_location: Mark the field as a location to track.  This is
 *   only used for fields of type ParseLoc, which otherwise are not jumbled.
 *
 * - read_as(VALUE): In nodeRead(), replace the field's value with VALUE.
 *
 * - read_write_ignore: Ignore the field for read/write.  This is only allowed
 *   if the node type is marked no_read or read_as() is also specified.
 *
 * - write_only_relids, write_only_nondefault_pathtarget, write_only_req_outer:
 *   Special handling for Path struct; see there.
 *
 */
#define pg_node_attr(...)
 
/*
 * The first field of a node of any type is guaranteed to be the NodeTag.
 * Hence the type of any node can be gotten by casting it to Node. Declaring
 * a variable to be of Node * (instead of void *) can also facilitate
 * debugging.
 */
typedef struct Node
{
    NodeTag     type;
} Node;
 
#define nodeTag(nodeptr)        (((const Node*)(nodeptr))->type)
 
/*
 * newNode -
 *    create a new node of the specified size and tag the node with the
 *    specified tag.
 *
 * !WARNING!: Avoid using newNode directly. You should be using the
 *    macro makeNode.  eg. to create a Query node, use makeNode(Query)
 */
static inline Node *
newNode(size_t size, NodeTag tag)
{
    Node       *result;
 
    Assert(size >= sizeof(Node));   /* need the tag, at least */
    result = (Node *) palloc0(size);
    result->type = tag;
 
    return result;
}
 
#define makeNode(_type_)        ((_type_ *) newNode(sizeof(_type_),T_##_type_))
#define NodeSetTag(nodeptr,t)   (((Node*)(nodeptr))->type = (t))
 
#define IsA(nodeptr,_type_)     (nodeTag(nodeptr) == T_##_type_)
 
/*
 * castNode(type, ptr) casts ptr to "type *", and if assertions are enabled,
 * verifies that the node has the appropriate type (using its nodeTag()).
 *
 * Use an inline function when assertions are enabled, to avoid multiple
 * evaluations of the ptr argument (which could e.g. be a function call).
 */
#ifdef USE_ASSERT_CHECKING
static inline Node *
castNodeImpl(NodeTag type, void *ptr)
{
    Assert(ptr == NULL || nodeTag(ptr) == type);
    return (Node *) ptr;
}
#define castNode(_type_, nodeptr) ((_type_ *) castNodeImpl(T_##_type_, nodeptr))
#else
#define castNode(_type_, nodeptr) ((_type_ *) (nodeptr))
#endif                          /* USE_ASSERT_CHECKING */
 
 
/* ----------------------------------------------------------------
 *                    extern declarations follow
 * ----------------------------------------------------------------
 */
 
#ifndef FRONTEND
 
/*
 * nodes/{outfuncs.c,print.c}
 */
struct Bitmapset;               /* not to include bitmapset.h here */
struct StringInfoData;          /* not to include stringinfo.h here */
 
extern void outNode(struct StringInfoData *str, const void *obj);
extern void outToken(struct StringInfoData *str, const char *s);
extern void outBitmapset(struct StringInfoData *str,
                         const struct Bitmapset *bms);
extern void outDatum(struct StringInfoData *str, Datum value,
                     int typlen, bool typbyval);
extern char *nodeToString(const void *obj);
extern char *nodeToStringWithLocations(const void *obj);
extern char *bmsToString(const struct Bitmapset *bms);
 
/*
 * nodes/{readfuncs.c,read.c}
 */
extern void *stringToNode(const char *str);
#ifdef DEBUG_NODE_TESTS_ENABLED
extern void *stringToNodeWithLocations(const char *str);
#endif
extern struct Bitmapset *readBitmapset(void);
extern Datum readDatum(bool typbyval);
extern bool *readBoolCols(int numCols);
extern int *readIntCols(int numCols);
extern Oid *readOidCols(int numCols);
extern int16 *readAttrNumberCols(int numCols);
 
/*
 * nodes/copyfuncs.c
 */
extern void *copyObjectImpl(const void *from);
 
/* cast result back to argument type, if supported by compiler */
#ifdef HAVE_TYPEOF_UNQUAL
#define copyObject(obj) ((typeof_unqual(*(obj)) *) copyObjectImpl(obj))
#else
#define copyObject(obj) copyObjectImpl(obj)
#endif
 
/*
 * nodes/equalfuncs.c
 */
extern bool equal(const void *a, const void *b);
 
#endif                          /* !FRONTEND */
 
 
/*
 * Typedef for parse location.  This is just an int, but this way
 * gen_node_support.pl knows which fields should get special treatment for
 * location values.
 *
 * -1 is used for unknown.
 */
typedef int ParseLoc;
 
/*
 * Typedefs for identifying qualifier selectivities, plan costs, and row
 * counts as such.  These are just plain "double"s, but declaring a variable
 * as Selectivity, Cost, or Cardinality makes the intent more obvious.
 *
 * These could have gone into plannodes.h or some such, but many files
 * depend on them...
 */
typedef double Selectivity;     /* fraction of tuples a qualifier will pass */
typedef double Cost;            /* execution cost (in page-access units) */
typedef double Cardinality;     /* (estimated) number of rows or other integer
                                 * count */
 
 
/*
 * CmdType -
 *    enums for type of operation represented by a Query or PlannedStmt
 *
 * This is needed in both parsenodes.h and plannodes.h, so put it here...
 */
typedef enum CmdType
{
    CMD_UNKNOWN,
    CMD_SELECT,                 /* select stmt */
    CMD_UPDATE,                 /* update stmt */
    CMD_INSERT,                 /* insert stmt */
    CMD_DELETE,                 /* delete stmt */
    CMD_MERGE,                  /* merge stmt */
    CMD_UTILITY,                /* cmds like create, destroy, copy, vacuum,
                                 * etc. */
    CMD_NOTHING,                /* dummy command for instead nothing rules
                                 * with qual */
} CmdType;
 
 
/*
 * JoinType -
 *    enums for types of relation joins
 *
 * JoinType determines the exact semantics of joining two relations using
 * a matching qualification.  For example, it tells what to do with a tuple
 * that has no match in the other relation.
 *
 * This is needed in both parsenodes.h and plannodes.h, so put it here...
 */
typedef enum JoinType
{
    /*
     * The canonical kinds of joins according to the SQL JOIN syntax. Only
     * these codes can appear in parser output (e.g., JoinExpr nodes).
     */
    JOIN_INNER,                 /* matching tuple pairs only */
    JOIN_LEFT,                  /* pairs + unmatched LHS tuples */
    JOIN_FULL,                  /* pairs + unmatched LHS + unmatched RHS */
    JOIN_RIGHT,                 /* pairs + unmatched RHS tuples */
 
    /*
     * Semijoins and anti-semijoins (as defined in relational theory) do not
     * appear in the SQL JOIN syntax, but there are standard idioms for
     * representing them (e.g., using EXISTS).  The planner recognizes these
     * cases and converts them to joins.  So the planner and executor must
     * support these codes.  NOTE: in JOIN_SEMI output, it is unspecified
     * which matching RHS row is joined to.  In JOIN_ANTI output, the row is
     * guaranteed to be null-extended.
     */
    JOIN_SEMI,                  /* 1 copy of each LHS row that has match(es) */
    JOIN_ANTI,                  /* 1 copy of each LHS row that has no match */
    JOIN_RIGHT_SEMI,            /* 1 copy of each RHS row that has match(es) */
    JOIN_RIGHT_ANTI,            /* 1 copy of each RHS row that has no match */
 
    /*
     * These codes are used internally in the planner, but are not supported
     * by the executor (nor, indeed, by most of the planner).
     */
    JOIN_UNIQUE_OUTER,          /* LHS has be made unique */
    JOIN_UNIQUE_INNER,          /* RHS has be made unique */
 
    /*
     * We might need additional join types someday.
     */
} JoinType;
 
/*
 * OUTER joins are those for which pushed-down quals must behave differently
 * from the join's own quals.  This is in fact everything except INNER, SEMI
 * and RIGHT_SEMI joins.  However, this macro must also exclude the
 * JOIN_UNIQUE symbols since those are temporary proxies for what will
 * eventually be an INNER join.
 *
 * Note: semijoins are a hybrid case, but we choose to treat them as not
 * being outer joins.  This is okay principally because the SQL syntax makes
 * it impossible to have a pushed-down qual that refers to the inner relation
 * of a semijoin; so there is no strong need to distinguish join quals from
 * pushed-down quals.  This is convenient because for almost all purposes,
 * quals attached to a semijoin can be treated the same as innerjoin quals.
 */
#define IS_OUTER_JOIN(jointype) \
    (((1 << (jointype)) & \
      ((1 << JOIN_LEFT) | \
       (1 << JOIN_FULL) | \
       (1 << JOIN_RIGHT) | \
       (1 << JOIN_ANTI) | \
       (1 << JOIN_RIGHT_ANTI))) != 0)
 
/*
 * AggStrategy -
 *    overall execution strategies for Agg plan nodes
 *
 * This is needed in both pathnodes.h and plannodes.h, so put it here...
 */
typedef enum AggStrategy
{
    AGG_PLAIN,                  /* simple agg across all input rows */
    AGG_SORTED,                 /* grouped agg, input must be sorted */
    AGG_HASHED,                 /* grouped agg, use internal hashtable */
    AGG_MIXED,                  /* grouped agg, hash and sort both used */
} AggStrategy;
 
/*
 * AggSplit -
 *    splitting (partial aggregation) modes for Agg plan nodes
 *
 * This is needed in both pathnodes.h and plannodes.h, so put it here...
 */
 
/* Primitive options supported by nodeAgg.c: */
#define AGGSPLITOP_COMBINE      0x01    /* substitute combinefn for transfn */
#define AGGSPLITOP_SKIPFINAL    0x02    /* skip finalfn, return state as-is */
#define AGGSPLITOP_SERIALIZE    0x04    /* apply serialfn to output */
#define AGGSPLITOP_DESERIALIZE  0x08    /* apply deserialfn to input */
 
/* Supported operating modes (i.e., useful combinations of these options): */
typedef enum AggSplit
{
    /* Basic, non-split aggregation: */
    AGGSPLIT_SIMPLE = 0,
    /* Initial phase of partial aggregation, with serialization: */
    AGGSPLIT_INITIAL_SERIAL = AGGSPLITOP_SKIPFINAL | AGGSPLITOP_SERIALIZE,
    /* Final phase of partial aggregation, with deserialization: */
    AGGSPLIT_FINAL_DESERIAL = AGGSPLITOP_COMBINE | AGGSPLITOP_DESERIALIZE,
} AggSplit;
 
/* Test whether an AggSplit value selects each primitive option: */
#define DO_AGGSPLIT_COMBINE(as)     (((as) & AGGSPLITOP_COMBINE) != 0)
#define DO_AGGSPLIT_SKIPFINAL(as)   (((as) & AGGSPLITOP_SKIPFINAL) != 0)
#define DO_AGGSPLIT_SERIALIZE(as)   (((as) & AGGSPLITOP_SERIALIZE) != 0)
#define DO_AGGSPLIT_DESERIALIZE(as) (((as) & AGGSPLITOP_DESERIALIZE) != 0)
 
/*
 * SetOpCmd and SetOpStrategy -
 *    overall semantics and execution strategies for SetOp plan nodes
 *
 * This is needed in both pathnodes.h and plannodes.h, so put it here...
 */
typedef enum SetOpCmd
{
    SETOPCMD_INTERSECT,
    SETOPCMD_INTERSECT_ALL,
    SETOPCMD_EXCEPT,
    SETOPCMD_EXCEPT_ALL,
} SetOpCmd;
 
typedef enum SetOpStrategy
{
    SETOP_SORTED,               /* input must be sorted */
    SETOP_HASHED,               /* use internal hashtable */
} SetOpStrategy;
 
/*
 * OnConflictAction -
 *    "ON CONFLICT" clause type of query
 *
 * This is needed in both parsenodes.h and plannodes.h, so put it here...
 */
typedef enum OnConflictAction
{
    ONCONFLICT_NONE,            /* No "ON CONFLICT" clause */
    ONCONFLICT_NOTHING,         /* ON CONFLICT ... DO NOTHING */
    ONCONFLICT_UPDATE,          /* ON CONFLICT ... DO UPDATE */
    ONCONFLICT_SELECT,          /* ON CONFLICT ... DO SELECT */
} OnConflictAction;
 
/*
 * LimitOption -
 *  LIMIT option of query
 *
 * This is needed in both parsenodes.h and plannodes.h, so put it here...
 */
typedef enum LimitOption
{
    LIMIT_OPTION_COUNT,         /* FETCH FIRST... ONLY */
    LIMIT_OPTION_WITH_TIES,     /* FETCH FIRST... WITH TIES */
} LimitOption;
 
#endif                          /* NODES_H */