plpgsql.h

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/*-------------------------------------------------------------------------
 *
 * plpgsql.h        - Definitions for the PL/pgSQL
 *            procedural language
 *
 * Portions Copyright (c) 1996-2021, PostgreSQL Global Development Group
 * Portions Copyright (c) 1994, Regents of the University of California
 *
 *
 * IDENTIFICATION
 *    src/pl/plpgsql/src/plpgsql.h
 *
 *-------------------------------------------------------------------------
 */

#ifndef PLPGSQL_H
#define PLPGSQL_H

#include "access/xact.h"
#include "commands/event_trigger.h"
#include "commands/trigger.h"
#include "executor/spi.h"
#include "utils/expandedrecord.h"
#include "utils/typcache.h"


/**********************************************************************
 * Definitions
 **********************************************************************/

/* define our text domain for translations */
#undef TEXTDOMAIN
#define TEXTDOMAIN PG_TEXTDOMAIN("plpgsql")

#undef _
#define _(x) dgettext(TEXTDOMAIN, x)

/*
 * Compiler's namespace item types
 */
typedef enum PLpgSQL_nsitem_type
{
    PLPGSQL_NSTYPE_LABEL,       /* block label */
    PLPGSQL_NSTYPE_VAR,         /* scalar variable */
    PLPGSQL_NSTYPE_REC          /* composite variable */
} PLpgSQL_nsitem_type;

/*
 * A PLPGSQL_NSTYPE_LABEL stack entry must be one of these types
 */
typedef enum PLpgSQL_label_type
{
    PLPGSQL_LABEL_BLOCK,        /* DECLARE/BEGIN block */
    PLPGSQL_LABEL_LOOP,         /* looping construct */
    PLPGSQL_LABEL_OTHER         /* anything else */
} PLpgSQL_label_type;

/*
 * Datum array node types
 */
typedef enum PLpgSQL_datum_type
{
    PLPGSQL_DTYPE_VAR,
    PLPGSQL_DTYPE_ROW,
    PLPGSQL_DTYPE_REC,
    PLPGSQL_DTYPE_RECFIELD,
    PLPGSQL_DTYPE_PROMISE
} PLpgSQL_datum_type;

/*
 * DTYPE_PROMISE datums have these possible ways of computing the promise
 */
typedef enum PLpgSQL_promise_type
{
    PLPGSQL_PROMISE_NONE = 0,   /* not a promise, or promise satisfied */
    PLPGSQL_PROMISE_TG_NAME,
    PLPGSQL_PROMISE_TG_WHEN,
    PLPGSQL_PROMISE_TG_LEVEL,
    PLPGSQL_PROMISE_TG_OP,
    PLPGSQL_PROMISE_TG_RELID,
    PLPGSQL_PROMISE_TG_TABLE_NAME,
    PLPGSQL_PROMISE_TG_TABLE_SCHEMA,
    PLPGSQL_PROMISE_TG_NARGS,
    PLPGSQL_PROMISE_TG_ARGV,
    PLPGSQL_PROMISE_TG_EVENT,
    PLPGSQL_PROMISE_TG_TAG
} PLpgSQL_promise_type;

/*
 * Variants distinguished in PLpgSQL_type structs
 */
typedef enum PLpgSQL_type_type
{
    PLPGSQL_TTYPE_SCALAR,       /* scalar types and domains */
    PLPGSQL_TTYPE_REC,          /* composite types, including RECORD */
    PLPGSQL_TTYPE_PSEUDO        /* pseudotypes */
} PLpgSQL_type_type;

/*
 * Execution tree node types
 */
typedef enum PLpgSQL_stmt_type
{
    PLPGSQL_STMT_BLOCK,
    PLPGSQL_STMT_ASSIGN,
    PLPGSQL_STMT_IF,
    PLPGSQL_STMT_CASE,
    PLPGSQL_STMT_LOOP,
    PLPGSQL_STMT_WHILE,
    PLPGSQL_STMT_FORI,
    PLPGSQL_STMT_FORS,
    PLPGSQL_STMT_FORC,
    PLPGSQL_STMT_FOREACH_A,
    PLPGSQL_STMT_EXIT,
    PLPGSQL_STMT_RETURN,
    PLPGSQL_STMT_RETURN_NEXT,
    PLPGSQL_STMT_RETURN_QUERY,
    PLPGSQL_STMT_RAISE,
    PLPGSQL_STMT_ASSERT,
    PLPGSQL_STMT_EXECSQL,
    PLPGSQL_STMT_DYNEXECUTE,
    PLPGSQL_STMT_DYNFORS,
    PLPGSQL_STMT_GETDIAG,
    PLPGSQL_STMT_OPEN,
    PLPGSQL_STMT_FETCH,
    PLPGSQL_STMT_CLOSE,
    PLPGSQL_STMT_PERFORM,
    PLPGSQL_STMT_CALL,
    PLPGSQL_STMT_COMMIT,
    PLPGSQL_STMT_ROLLBACK,
    PLPGSQL_STMT_SET
} PLpgSQL_stmt_type;

/*
 * Execution node return codes
 */
enum
{
    PLPGSQL_RC_OK,
    PLPGSQL_RC_EXIT,
    PLPGSQL_RC_RETURN,
    PLPGSQL_RC_CONTINUE
};

/*
 * GET DIAGNOSTICS information items
 */
typedef enum PLpgSQL_getdiag_kind
{
    PLPGSQL_GETDIAG_ROW_COUNT,
    PLPGSQL_GETDIAG_CONTEXT,
    PLPGSQL_GETDIAG_ERROR_CONTEXT,
    PLPGSQL_GETDIAG_ERROR_DETAIL,
    PLPGSQL_GETDIAG_ERROR_HINT,
    PLPGSQL_GETDIAG_RETURNED_SQLSTATE,
    PLPGSQL_GETDIAG_COLUMN_NAME,
    PLPGSQL_GETDIAG_CONSTRAINT_NAME,
    PLPGSQL_GETDIAG_DATATYPE_NAME,
    PLPGSQL_GETDIAG_MESSAGE_TEXT,
    PLPGSQL_GETDIAG_TABLE_NAME,
    PLPGSQL_GETDIAG_SCHEMA_NAME
} PLpgSQL_getdiag_kind;

/*
 * RAISE statement options
 */
typedef enum PLpgSQL_raise_option_type
{
    PLPGSQL_RAISEOPTION_ERRCODE,
    PLPGSQL_RAISEOPTION_MESSAGE,
    PLPGSQL_RAISEOPTION_DETAIL,
    PLPGSQL_RAISEOPTION_HINT,
    PLPGSQL_RAISEOPTION_COLUMN,
    PLPGSQL_RAISEOPTION_CONSTRAINT,
    PLPGSQL_RAISEOPTION_DATATYPE,
    PLPGSQL_RAISEOPTION_TABLE,
    PLPGSQL_RAISEOPTION_SCHEMA
} PLpgSQL_raise_option_type;

/*
 * Behavioral modes for plpgsql variable resolution
 */
typedef enum PLpgSQL_resolve_option
{
    PLPGSQL_RESOLVE_ERROR,      /* throw error if ambiguous */
    PLPGSQL_RESOLVE_VARIABLE,   /* prefer plpgsql var to table column */
    PLPGSQL_RESOLVE_COLUMN      /* prefer table column to plpgsql var */
} PLpgSQL_resolve_option;


/**********************************************************************
 * Node and structure definitions
 **********************************************************************/

/*
 * Postgres data type
 */
typedef struct PLpgSQL_type
{
    char       *typname;        /* (simple) name of the type */
    Oid         typoid;         /* OID of the data type */
    PLpgSQL_type_type ttype;    /* PLPGSQL_TTYPE_ code */
    int16       typlen;         /* stuff copied from its pg_type entry */
    bool        typbyval;
    char        typtype;
    Oid         collation;      /* from pg_type, but can be overridden */
    bool        typisarray;     /* is "true" array, or domain over one */
    int32       atttypmod;      /* typmod (taken from someplace else) */
    /* Remaining fields are used only for named composite types (not RECORD) */
    TypeName   *origtypname;    /* type name as written by user */
    TypeCacheEntry *tcache;     /* typcache entry for composite type */
    uint64      tupdesc_id;     /* last-seen tupdesc identifier */
} PLpgSQL_type;

/*
 * SQL Query to plan and execute
 */
typedef struct PLpgSQL_expr
{
    char       *query;          /* query string, verbatim from function body */
    RawParseMode parseMode;     /* raw_parser() mode to use */
    SPIPlanPtr  plan;           /* plan, or NULL if not made yet */
    Bitmapset  *paramnos;       /* all dnos referenced by this query */

    /* function containing this expr (not set until we first parse query) */
    struct PLpgSQL_function *func;

    /* namespace chain visible to this expr */
    struct PLpgSQL_nsitem *ns;

    /* fields for "simple expression" fast-path execution: */
    Expr       *expr_simple_expr;   /* NULL means not a simple expr */
    Oid         expr_simple_type;   /* result type Oid, if simple */
    int32       expr_simple_typmod; /* result typmod, if simple */
    bool        expr_simple_mutable;    /* true if simple expr is mutable */

    /*
     * These fields are used to optimize assignments to expanded-datum
     * variables.  If this expression is the source of an assignment to a
     * simple variable, target_param holds that variable's dno; else it's -1.
     * If we match a Param within expr_simple_expr to such a variable, that
     * Param's address is stored in expr_rw_param; then expression code
     * generation will allow the value for that Param to be passed read/write.
     */
    int         target_param;   /* dno of assign target, or -1 if none */
    Param      *expr_rw_param;  /* read/write Param within expr, if any */

    /*
     * If the expression was ever determined to be simple, we remember its
     * CachedPlanSource and CachedPlan here.  If expr_simple_plan_lxid matches
     * current LXID, then we hold a refcount on expr_simple_plan in the
     * current transaction.  Otherwise we need to get one before re-using it.
     */
    CachedPlanSource *expr_simple_plansource;   /* extracted from "plan" */
    CachedPlan *expr_simple_plan;   /* extracted from "plan" */
    LocalTransactionId expr_simple_plan_lxid;

    /*
     * if expr is simple AND prepared in current transaction,
     * expr_simple_state and expr_simple_in_use are valid. Test validity by
     * seeing if expr_simple_lxid matches current LXID.  (If not,
     * expr_simple_state probably points at garbage!)
     */
    ExprState  *expr_simple_state;  /* eval tree for expr_simple_expr */
    bool        expr_simple_in_use; /* true if eval tree is active */
    LocalTransactionId expr_simple_lxid;
} PLpgSQL_expr;

/*
 * Generic datum array item
 *
 * PLpgSQL_datum is the common supertype for PLpgSQL_var, PLpgSQL_row,
 * PLpgSQL_rec, and PLpgSQL_recfield.
 */
typedef struct PLpgSQL_datum
{
    PLpgSQL_datum_type dtype;
    int         dno;
} PLpgSQL_datum;

/*
 * Scalar or composite variable
 *
 * The variants PLpgSQL_var, PLpgSQL_row, and PLpgSQL_rec share these
 * fields.
 */
typedef struct PLpgSQL_variable
{
    PLpgSQL_datum_type dtype;
    int         dno;
    char       *refname;
    int         lineno;
    bool        isconst;
    bool        notnull;
    PLpgSQL_expr *default_val;
} PLpgSQL_variable;

/*
 * Scalar variable
 *
 * DTYPE_VAR and DTYPE_PROMISE datums both use this struct type.
 * A PROMISE datum works exactly like a VAR datum for most purposes,
 * but if it is read without having previously been assigned to, then
 * a special "promised" value is computed and assigned to the datum
 * before the read is performed.  This technique avoids the overhead of
 * computing the variable's value in cases where we expect that many
 * functions will never read it.
 */
typedef struct PLpgSQL_var
{
    PLpgSQL_datum_type dtype;
    int         dno;
    char       *refname;
    int         lineno;
    bool        isconst;
    bool        notnull;
    PLpgSQL_expr *default_val;
    /* end of PLpgSQL_variable fields */

    PLpgSQL_type *datatype;

    /*
     * Variables declared as CURSOR FOR <query> are mostly like ordinary
     * scalar variables of type refcursor, but they have these additional
     * properties:
     */
    PLpgSQL_expr *cursor_explicit_expr;
    int         cursor_explicit_argrow;
    int         cursor_options;

    /* Fields below here can change at runtime */

    Datum       value;
    bool        isnull;
    bool        freeval;

    /*
     * The promise field records which "promised" value to assign if the
     * promise must be honored.  If it's a normal variable, or the promise has
     * been fulfilled, this is PLPGSQL_PROMISE_NONE.
     */
    PLpgSQL_promise_type promise;
} PLpgSQL_var;

/*
 * Row variable - this represents one or more variables that are listed in an
 * INTO clause, FOR-loop targetlist, cursor argument list, etc.  We also use
 * a row to represent a function's OUT parameters when there's more than one.
 *
 * Note that there's no way to name the row as such from PL/pgSQL code,
 * so many functions don't need to support these.
 *
 * That also means that there's no real name for the row variable, so we
 * conventionally set refname to "(unnamed row)".  We could leave it NULL,
 * but it's too convenient to be able to assume that refname is valid in
 * all variants of PLpgSQL_variable.
 *
 * isconst, notnull, and default_val are unsupported (and hence
 * always zero/null) for a row.  The member variables of a row should have
 * been checked to be writable at compile time, so isconst is correctly set
 * to false.  notnull and default_val aren't applicable.
 */
typedef struct PLpgSQL_row
{
    PLpgSQL_datum_type dtype;
    int         dno;
    char       *refname;
    int         lineno;
    bool        isconst;
    bool        notnull;
    PLpgSQL_expr *default_val;
    /* end of PLpgSQL_variable fields */

    /*
     * rowtupdesc is only set up if we might need to convert the row into a
     * composite datum, which currently only happens for OUT parameters.
     * Otherwise it is NULL.
     */
    TupleDesc   rowtupdesc;

    int         nfields;
    char      **fieldnames;
    int        *varnos;
} PLpgSQL_row;

/*
 * Record variable (any composite type, including RECORD)
 */
typedef struct PLpgSQL_rec
{
    PLpgSQL_datum_type dtype;
    int         dno;
    char       *refname;
    int         lineno;
    bool        isconst;
    bool        notnull;
    PLpgSQL_expr *default_val;
    /* end of PLpgSQL_variable fields */

    /*
     * Note: for non-RECORD cases, we may from time to time re-look-up the
     * composite type, using datatype->origtypname.  That can result in
     * changing rectypeid.
     */

    PLpgSQL_type *datatype;     /* can be NULL, if rectypeid is RECORDOID */
    Oid         rectypeid;      /* declared type of variable */
    /* RECFIELDs for this record are chained together for easy access */
    int         firstfield;     /* dno of first RECFIELD, or -1 if none */

    /* Fields below here can change at runtime */

    /* We always store record variables as "expanded" records */
    ExpandedRecordHeader *erh;
} PLpgSQL_rec;

/*
 * Field in record
 */
typedef struct PLpgSQL_recfield
{
    PLpgSQL_datum_type dtype;
    int         dno;
    /* end of PLpgSQL_datum fields */

    char       *fieldname;      /* name of field */
    int         recparentno;    /* dno of parent record */
    int         nextfield;      /* dno of next child, or -1 if none */
    uint64      rectupledescid; /* record's tupledesc ID as of last lookup */
    ExpandedRecordFieldInfo finfo;  /* field's attnum and type info */
    /* if rectupledescid == INVALID_TUPLEDESC_IDENTIFIER, finfo isn't valid */
} PLpgSQL_recfield;

/*
 * Item in the compilers namespace tree
 */
typedef struct PLpgSQL_nsitem
{
    PLpgSQL_nsitem_type itemtype;

    /*
     * For labels, itemno is a value of enum PLpgSQL_label_type. For other
     * itemtypes, itemno is the associated PLpgSQL_datum's dno.
     */
    int         itemno;
    struct PLpgSQL_nsitem *prev;
    char        name[FLEXIBLE_ARRAY_MEMBER];    /* nul-terminated string */
} PLpgSQL_nsitem;

/*
 * Generic execution node
 */
typedef struct PLpgSQL_stmt
{
    PLpgSQL_stmt_type cmd_type;
    int         lineno;

    /*
     * Unique statement ID in this function (starting at 1; 0 is invalid/not
     * set).  This can be used by a profiler as the index for an array of
     * per-statement metrics.
     */
    unsigned int stmtid;
} PLpgSQL_stmt;

/*
 * One EXCEPTION condition name
 */
typedef struct PLpgSQL_condition
{
    int         sqlerrstate;    /* SQLSTATE code */
    char       *condname;       /* condition name (for debugging) */
    struct PLpgSQL_condition *next;
} PLpgSQL_condition;

/*
 * EXCEPTION block
 */
typedef struct PLpgSQL_exception_block
{
    int         sqlstate_varno;
    int         sqlerrm_varno;
    List       *exc_list;       /* List of WHEN clauses */
} PLpgSQL_exception_block;

/*
 * One EXCEPTION ... WHEN clause
 */
typedef struct PLpgSQL_exception
{
    int         lineno;
    PLpgSQL_condition *conditions;
    List       *action;         /* List of statements */
} PLpgSQL_exception;

/*
 * Block of statements
 */
typedef struct PLpgSQL_stmt_block
{
    PLpgSQL_stmt_type cmd_type;
    int         lineno;
    unsigned int stmtid;
    char       *label;
    List       *body;           /* List of statements */
    int         n_initvars;     /* Length of initvarnos[] */
    int        *initvarnos;     /* dnos of variables declared in this block */
    PLpgSQL_exception_block *exceptions;
} PLpgSQL_stmt_block;

/*
 * Assign statement
 */
typedef struct PLpgSQL_stmt_assign
{
    PLpgSQL_stmt_type cmd_type;
    int         lineno;
    unsigned int stmtid;
    int         varno;
    PLpgSQL_expr *expr;
} PLpgSQL_stmt_assign;

/*
 * PERFORM statement
 */
typedef struct PLpgSQL_stmt_perform
{
    PLpgSQL_stmt_type cmd_type;
    int         lineno;
    unsigned int stmtid;
    PLpgSQL_expr *expr;
} PLpgSQL_stmt_perform;

/*
 * CALL statement
 */
typedef struct PLpgSQL_stmt_call
{
    PLpgSQL_stmt_type cmd_type;
    int         lineno;
    unsigned int stmtid;
    PLpgSQL_expr *expr;
    bool        is_call;
    PLpgSQL_variable *target;
} PLpgSQL_stmt_call;

/*
 * COMMIT statement
 */
typedef struct PLpgSQL_stmt_commit
{
    PLpgSQL_stmt_type cmd_type;
    int         lineno;
    unsigned int stmtid;
    bool        chain;
} PLpgSQL_stmt_commit;

/*
 * ROLLBACK statement
 */
typedef struct PLpgSQL_stmt_rollback
{
    PLpgSQL_stmt_type cmd_type;
    int         lineno;
    unsigned int stmtid;
    bool        chain;
} PLpgSQL_stmt_rollback;

/*
 * SET statement
 */
typedef struct PLpgSQL_stmt_set
{
    PLpgSQL_stmt_type cmd_type;
    int         lineno;
    unsigned int stmtid;
    PLpgSQL_expr *expr;
} PLpgSQL_stmt_set;

/*
 * GET DIAGNOSTICS item
 */
typedef struct PLpgSQL_diag_item
{
    PLpgSQL_getdiag_kind kind;  /* id for diagnostic value desired */
    int         target;         /* where to assign it */
} PLpgSQL_diag_item;

/*
 * GET DIAGNOSTICS statement
 */
typedef struct PLpgSQL_stmt_getdiag
{
    PLpgSQL_stmt_type cmd_type;
    int         lineno;
    unsigned int stmtid;
    bool        is_stacked;     /* STACKED or CURRENT diagnostics area? */
    List       *diag_items;     /* List of PLpgSQL_diag_item */
} PLpgSQL_stmt_getdiag;

/*
 * IF statement
 */
typedef struct PLpgSQL_stmt_if
{
    PLpgSQL_stmt_type cmd_type;
    int         lineno;
    unsigned int stmtid;
    PLpgSQL_expr *cond;         /* boolean expression for THEN */
    List       *then_body;      /* List of statements */
    List       *elsif_list;     /* List of PLpgSQL_if_elsif structs */
    List       *else_body;      /* List of statements */
} PLpgSQL_stmt_if;

/*
 * one ELSIF arm of IF statement
 */
typedef struct PLpgSQL_if_elsif
{
    int         lineno;
    PLpgSQL_expr *cond;         /* boolean expression for this case */
    List       *stmts;          /* List of statements */
} PLpgSQL_if_elsif;

/*
 * CASE statement
 */
typedef struct PLpgSQL_stmt_case
{
    PLpgSQL_stmt_type cmd_type;
    int         lineno;
    unsigned int stmtid;
    PLpgSQL_expr *t_expr;       /* test expression, or NULL if none */
    int         t_varno;        /* var to store test expression value into */
    List       *case_when_list; /* List of PLpgSQL_case_when structs */
    bool        have_else;      /* flag needed because list could be empty */
    List       *else_stmts;     /* List of statements */
} PLpgSQL_stmt_case;

/*
 * one arm of CASE statement
 */
typedef struct PLpgSQL_case_when
{
    int         lineno;
    PLpgSQL_expr *expr;         /* boolean expression for this case */
    List       *stmts;          /* List of statements */
} PLpgSQL_case_when;

/*
 * Unconditional LOOP statement
 */
typedef struct PLpgSQL_stmt_loop
{
    PLpgSQL_stmt_type cmd_type;
    int         lineno;
    unsigned int stmtid;
    char       *label;
    List       *body;           /* List of statements */
} PLpgSQL_stmt_loop;

/*
 * WHILE cond LOOP statement
 */
typedef struct PLpgSQL_stmt_while
{
    PLpgSQL_stmt_type cmd_type;
    int         lineno;
    unsigned int stmtid;
    char       *label;
    PLpgSQL_expr *cond;
    List       *body;           /* List of statements */
} PLpgSQL_stmt_while;

/*
 * FOR statement with integer loopvar
 */
typedef struct PLpgSQL_stmt_fori
{
    PLpgSQL_stmt_type cmd_type;
    int         lineno;
    unsigned int stmtid;
    char       *label;
    PLpgSQL_var *var;
    PLpgSQL_expr *lower;
    PLpgSQL_expr *upper;
    PLpgSQL_expr *step;         /* NULL means default (ie, BY 1) */
    int         reverse;
    List       *body;           /* List of statements */
} PLpgSQL_stmt_fori;

/*
 * PLpgSQL_stmt_forq represents a FOR statement running over a SQL query.
 * It is the common supertype of PLpgSQL_stmt_fors, PLpgSQL_stmt_forc
 * and PLpgSQL_stmt_dynfors.
 */
typedef struct PLpgSQL_stmt_forq
{
    PLpgSQL_stmt_type cmd_type;
    int         lineno;
    unsigned int stmtid;
    char       *label;
    PLpgSQL_variable *var;      /* Loop variable (record or row) */
    List       *body;           /* List of statements */
} PLpgSQL_stmt_forq;

/*
 * FOR statement running over SELECT
 */
typedef struct PLpgSQL_stmt_fors
{
    PLpgSQL_stmt_type cmd_type;
    int         lineno;
    unsigned int stmtid;
    char       *label;
    PLpgSQL_variable *var;      /* Loop variable (record or row) */
    List       *body;           /* List of statements */
    /* end of fields that must match PLpgSQL_stmt_forq */
    PLpgSQL_expr *query;
} PLpgSQL_stmt_fors;

/*
 * FOR statement running over cursor
 */
typedef struct PLpgSQL_stmt_forc
{
    PLpgSQL_stmt_type cmd_type;
    int         lineno;
    unsigned int stmtid;
    char       *label;
    PLpgSQL_variable *var;      /* Loop variable (record or row) */
    List       *body;           /* List of statements */
    /* end of fields that must match PLpgSQL_stmt_forq */
    int         curvar;
    PLpgSQL_expr *argquery;     /* cursor arguments if any */
} PLpgSQL_stmt_forc;

/*
 * FOR statement running over EXECUTE
 */
typedef struct PLpgSQL_stmt_dynfors
{
    PLpgSQL_stmt_type cmd_type;
    int         lineno;
    unsigned int stmtid;
    char       *label;
    PLpgSQL_variable *var;      /* Loop variable (record or row) */
    List       *body;           /* List of statements */
    /* end of fields that must match PLpgSQL_stmt_forq */
    PLpgSQL_expr *query;
    List       *params;         /* USING expressions */
} PLpgSQL_stmt_dynfors;

/*
 * FOREACH item in array loop
 */
typedef struct PLpgSQL_stmt_foreach_a
{
    PLpgSQL_stmt_type cmd_type;
    int         lineno;
    unsigned int stmtid;
    char       *label;
    int         varno;          /* loop target variable */
    int         slice;          /* slice dimension, or 0 */
    PLpgSQL_expr *expr;         /* array expression */
    List       *body;           /* List of statements */
} PLpgSQL_stmt_foreach_a;

/*
 * OPEN a curvar
 */
typedef struct PLpgSQL_stmt_open
{
    PLpgSQL_stmt_type cmd_type;
    int         lineno;
    unsigned int stmtid;
    int         curvar;
    int         cursor_options;
    PLpgSQL_expr *argquery;
    PLpgSQL_expr *query;
    PLpgSQL_expr *dynquery;
    List       *params;         /* USING expressions */
} PLpgSQL_stmt_open;

/*
 * FETCH or MOVE statement
 */
typedef struct PLpgSQL_stmt_fetch
{
    PLpgSQL_stmt_type cmd_type;
    int         lineno;
    unsigned int stmtid;
    PLpgSQL_variable *target;   /* target (record or row) */
    int         curvar;         /* cursor variable to fetch from */
    FetchDirection direction;   /* fetch direction */
    long        how_many;       /* count, if constant (expr is NULL) */
    PLpgSQL_expr *expr;         /* count, if expression */
    bool        is_move;        /* is this a fetch or move? */
    bool        returns_multiple_rows;  /* can return more than one row? */
} PLpgSQL_stmt_fetch;

/*
 * CLOSE curvar
 */
typedef struct PLpgSQL_stmt_close
{
    PLpgSQL_stmt_type cmd_type;
    int         lineno;
    unsigned int stmtid;
    int         curvar;
} PLpgSQL_stmt_close;

/*
 * EXIT or CONTINUE statement
 */
typedef struct PLpgSQL_stmt_exit
{
    PLpgSQL_stmt_type cmd_type;
    int         lineno;
    unsigned int stmtid;
    bool        is_exit;        /* Is this an exit or a continue? */
    char       *label;          /* NULL if it's an unlabeled EXIT/CONTINUE */
    PLpgSQL_expr *cond;
} PLpgSQL_stmt_exit;

/*
 * RETURN statement
 */
typedef struct PLpgSQL_stmt_return
{
    PLpgSQL_stmt_type cmd_type;
    int         lineno;
    unsigned int stmtid;
    PLpgSQL_expr *expr;
    int         retvarno;
} PLpgSQL_stmt_return;

/*
 * RETURN NEXT statement
 */
typedef struct PLpgSQL_stmt_return_next
{
    PLpgSQL_stmt_type cmd_type;
    int         lineno;
    unsigned int stmtid;
    PLpgSQL_expr *expr;
    int         retvarno;
} PLpgSQL_stmt_return_next;

/*
 * RETURN QUERY statement
 */
typedef struct PLpgSQL_stmt_return_query
{
    PLpgSQL_stmt_type cmd_type;
    int         lineno;
    unsigned int stmtid;
    PLpgSQL_expr *query;        /* if static query */
    PLpgSQL_expr *dynquery;     /* if dynamic query (RETURN QUERY EXECUTE) */
    List       *params;         /* USING arguments for dynamic query */
} PLpgSQL_stmt_return_query;

/*
 * RAISE statement
 */
typedef struct PLpgSQL_stmt_raise
{
    PLpgSQL_stmt_type cmd_type;
    int         lineno;
    unsigned int stmtid;
    int         elog_level;
    char       *condname;       /* condition name, SQLSTATE, or NULL */
    char       *message;        /* old-style message format literal, or NULL */
    List       *params;         /* list of expressions for old-style message */
    List       *options;        /* list of PLpgSQL_raise_option */
} PLpgSQL_stmt_raise;

/*
 * RAISE statement option
 */
typedef struct PLpgSQL_raise_option
{
    PLpgSQL_raise_option_type opt_type;
    PLpgSQL_expr *expr;
} PLpgSQL_raise_option;

/*
 * ASSERT statement
 */
typedef struct PLpgSQL_stmt_assert
{
    PLpgSQL_stmt_type cmd_type;
    int         lineno;
    unsigned int stmtid;
    PLpgSQL_expr *cond;
    PLpgSQL_expr *message;
} PLpgSQL_stmt_assert;

/*
 * Generic SQL statement to execute
 */
typedef struct PLpgSQL_stmt_execsql
{
    PLpgSQL_stmt_type cmd_type;
    int         lineno;
    unsigned int stmtid;
    PLpgSQL_expr *sqlstmt;
    bool        mod_stmt;       /* is the stmt INSERT/UPDATE/DELETE?  Note:
                                 * mod_stmt is set when we plan the query */
    bool        into;           /* INTO supplied? */
    bool        strict;         /* INTO STRICT flag */
    PLpgSQL_variable *target;   /* INTO target (record or row) */
} PLpgSQL_stmt_execsql;

/*
 * Dynamic SQL string to execute
 */
typedef struct PLpgSQL_stmt_dynexecute
{
    PLpgSQL_stmt_type cmd_type;
    int         lineno;
    unsigned int stmtid;
    PLpgSQL_expr *query;        /* string expression */
    bool        into;           /* INTO supplied? */
    bool        strict;         /* INTO STRICT flag */
    PLpgSQL_variable *target;   /* INTO target (record or row) */
    List       *params;         /* USING expressions */
} PLpgSQL_stmt_dynexecute;

/*
 * Hash lookup key for functions
 */
typedef struct PLpgSQL_func_hashkey
{
    Oid         funcOid;

    bool        isTrigger;      /* true if called as a DML trigger */
    bool        isEventTrigger; /* true if called as an event trigger */

    /* be careful that pad bytes in this struct get zeroed! */

    /*
     * For a trigger function, the OID of the trigger is part of the hash key
     * --- we want to compile the trigger function separately for each trigger
     * it is used with, in case the rowtype or transition table names are
     * different.  Zero if not called as a DML trigger.
     */
    Oid         trigOid;

    /*
     * We must include the input collation as part of the hash key too,
     * because we have to generate different plans (with different Param
     * collations) for different collation settings.
     */
    Oid         inputCollation;

    /*
     * We include actual argument types in the hash key to support polymorphic
     * PLpgSQL functions.  Be careful that extra positions are zeroed!
     */
    Oid         argtypes[FUNC_MAX_ARGS];
} PLpgSQL_func_hashkey;

/*
 * Trigger type
 */
typedef enum PLpgSQL_trigtype
{
    PLPGSQL_DML_TRIGGER,
    PLPGSQL_EVENT_TRIGGER,
    PLPGSQL_NOT_TRIGGER
} PLpgSQL_trigtype;

/*
 * Complete compiled function
 */
typedef struct PLpgSQL_function
{
    char       *fn_signature;
    Oid         fn_oid;
    TransactionId fn_xmin;
    ItemPointerData fn_tid;
    PLpgSQL_trigtype fn_is_trigger;
    Oid         fn_input_collation;
    PLpgSQL_func_hashkey *fn_hashkey;   /* back-link to hashtable key */
    MemoryContext fn_cxt;

    Oid         fn_rettype;
    int         fn_rettyplen;
    bool        fn_retbyval;
    bool        fn_retistuple;
    bool        fn_retisdomain;
    bool        fn_retset;
    bool        fn_readonly;
    char        fn_prokind;

    int         fn_nargs;
    int         fn_argvarnos[FUNC_MAX_ARGS];
    int         out_param_varno;
    int         found_varno;
    int         new_varno;
    int         old_varno;

    PLpgSQL_resolve_option resolve_option;

    bool        print_strict_params;

    /* extra checks */
    int         extra_warnings;
    int         extra_errors;

    /* the datums representing the function's local variables */
    int         ndatums;
    PLpgSQL_datum **datums;
    Size        copiable_size;  /* space for locally instantiated datums */

    /* function body parsetree */
    PLpgSQL_stmt_block *action;

    /* data derived while parsing body */
    unsigned int nstatements;   /* counter for assigning stmtids */
    bool        requires_procedure_resowner;    /* contains CALL or DO? */

    /* these fields change when the function is used */
    struct PLpgSQL_execstate *cur_estate;
    unsigned long use_count;
} PLpgSQL_function;

/*
 * Runtime execution data
 */
typedef struct PLpgSQL_execstate
{
    PLpgSQL_function *func;     /* function being executed */

    TriggerData *trigdata;      /* if regular trigger, data about firing */
    EventTriggerData *evtrigdata;   /* if event trigger, data about firing */

    Datum       retval;
    bool        retisnull;
    Oid         rettype;        /* type of current retval */

    Oid         fn_rettype;     /* info about declared function rettype */
    bool        retistuple;
    bool        retisset;

    bool        readonly_func;
    bool        atomic;

    char       *exitlabel;      /* the "target" label of the current EXIT or
                                 * CONTINUE stmt, if any */
    ErrorData  *cur_error;      /* current exception handler's error */

    Tuplestorestate *tuple_store;   /* SRFs accumulate results here */
    TupleDesc   tuple_store_desc;   /* descriptor for tuples in tuple_store */
    MemoryContext tuple_store_cxt;
    ResourceOwner tuple_store_owner;
    ReturnSetInfo *rsi;

    int         found_varno;

    /*
     * The datums representing the function's local variables.  Some of these
     * are local storage in this execstate, but some just point to the shared
     * copy belonging to the PLpgSQL_function, depending on whether or not we
     * need any per-execution state for the datum's dtype.
     */
    int         ndatums;
    PLpgSQL_datum **datums;
    /* context containing variable values (same as func's SPI_proc context) */
    MemoryContext datum_context;

    /*
     * paramLI is what we use to pass local variable values to the executor.
     * It does not have a ParamExternData array; we just dynamically
     * instantiate parameter data as needed.  By convention, PARAM_EXTERN
     * Params have paramid equal to the dno of the referenced local variable.
     */
    ParamListInfo paramLI;

    /* EState and resowner to use for "simple" expression evaluation */
    EState     *simple_eval_estate;
    ResourceOwner simple_eval_resowner;

    /* if running nonatomic procedure or DO block, resowner to use for CALL */
    ResourceOwner procedure_resowner;

    /* lookup table to use for executing type casts */
    HTAB       *cast_hash;
    MemoryContext cast_hash_context;

    /* memory context for statement-lifespan temporary values */
    MemoryContext stmt_mcontext;    /* current stmt context, or NULL if none */
    MemoryContext stmt_mcontext_parent; /* parent of current context */

    /* temporary state for results from evaluation of query or expr */
    SPITupleTable *eval_tuptable;
    uint64      eval_processed;
    ExprContext *eval_econtext; /* for executing simple expressions */

    /* status information for error context reporting */
    PLpgSQL_stmt *err_stmt;     /* current stmt */
    const char *err_text;       /* additional state info */

    void       *plugin_info;    /* reserved for use by optional plugin */
} PLpgSQL_execstate;

/*
 * A PLpgSQL_plugin structure represents an instrumentation plugin.
 * To instrument PL/pgSQL, a plugin library must access the rendezvous
 * variable "PLpgSQL_plugin" and set it to point to a PLpgSQL_plugin struct.
 * Typically the struct could just be static data in the plugin library.
 * We expect that a plugin would do this at library load time (_PG_init()).
 * It must also be careful to set the rendezvous variable back to NULL
 * if it is unloaded (_PG_fini()).
 *
 * This structure is basically a collection of function pointers --- at
 * various interesting points in pl_exec.c, we call these functions
 * (if the pointers are non-NULL) to give the plugin a chance to watch
 * what we are doing.
 *
 * func_setup is called when we start a function, before we've initialized
 * the local variables defined by the function.
 *
 * func_beg is called when we start a function, after we've initialized
 * the local variables.
 *
 * func_end is called at the end of a function.
 *
 * stmt_beg and stmt_end are called before and after (respectively) each
 * statement.
 *
 * Also, immediately before any call to func_setup, PL/pgSQL fills in the
 * error_callback and assign_expr fields with pointers to its own
 * plpgsql_exec_error_callback and exec_assign_expr functions.  This is
 * a somewhat ad-hoc expedient to simplify life for debugger plugins.
 */
typedef struct PLpgSQL_plugin
{
    /* Function pointers set up by the plugin */
    void        (*func_setup) (PLpgSQL_execstate *estate, PLpgSQL_function *func);
    void        (*func_beg) (PLpgSQL_execstate *estate, PLpgSQL_function *func);
    void        (*func_end) (PLpgSQL_execstate *estate, PLpgSQL_function *func);
    void        (*stmt_beg) (PLpgSQL_execstate *estate, PLpgSQL_stmt *stmt);
    void        (*stmt_end) (PLpgSQL_execstate *estate, PLpgSQL_stmt *stmt);

    /* Function pointers set by PL/pgSQL itself */
    void        (*error_callback) (void *arg);
    void        (*assign_expr) (PLpgSQL_execstate *estate, PLpgSQL_datum *target,
                                PLpgSQL_expr *expr);
} PLpgSQL_plugin;

/*
 * Struct types used during parsing
 */

typedef struct PLword
{
    char       *ident;          /* palloc'd converted identifier */
    bool        quoted;         /* Was it double-quoted? */
} PLword;

typedef struct PLcword
{
    List       *idents;         /* composite identifiers (list of String) */
} PLcword;

typedef struct PLwdatum
{
    PLpgSQL_datum *datum;       /* referenced variable */
    char       *ident;          /* valid if simple name */
    bool        quoted;
    List       *idents;         /* valid if composite name */
} PLwdatum;

/**********************************************************************
 * Global variable declarations
 **********************************************************************/

typedef enum
{
    IDENTIFIER_LOOKUP_NORMAL,   /* normal processing of var names */
    IDENTIFIER_LOOKUP_DECLARE,  /* In DECLARE --- don't look up names */
    IDENTIFIER_LOOKUP_EXPR      /* In SQL expression --- special case */
} IdentifierLookup;

extern IdentifierLookup plpgsql_IdentifierLookup;

extern int  plpgsql_variable_conflict;

extern bool plpgsql_print_strict_params;

extern bool plpgsql_check_asserts;

/* extra compile-time and run-time checks */
#define PLPGSQL_XCHECK_NONE                     0
#define PLPGSQL_XCHECK_SHADOWVAR                (1 << 1)
#define PLPGSQL_XCHECK_TOOMANYROWS              (1 << 2)
#define PLPGSQL_XCHECK_STRICTMULTIASSIGNMENT    (1 << 3)
#define PLPGSQL_XCHECK_ALL                      ((int) ~0)

extern int  plpgsql_extra_warnings;
extern int  plpgsql_extra_errors;

extern bool plpgsql_check_syntax;
extern bool plpgsql_DumpExecTree;

extern PLpgSQL_stmt_block *plpgsql_parse_result;

extern int  plpgsql_nDatums;
extern PLpgSQL_datum **plpgsql_Datums;

extern char *plpgsql_error_funcname;

extern PLpgSQL_function *plpgsql_curr_compile;
extern MemoryContext plpgsql_compile_tmp_cxt;

extern PLpgSQL_plugin **plpgsql_plugin_ptr;

/**********************************************************************
 * Function declarations
 **********************************************************************/

/*
 * Functions in pl_comp.c
 */
extern PLpgSQL_function *plpgsql_compile(FunctionCallInfo fcinfo,
                                         bool forValidator);
extern PLpgSQL_function *plpgsql_compile_inline(char *proc_source);
extern void plpgsql_parser_setup(struct ParseState *pstate,
                                 PLpgSQL_expr *expr);
extern bool plpgsql_parse_word(char *word1, const char *yytxt, bool lookup,
                               PLwdatum *wdatum, PLword *word);
extern bool plpgsql_parse_dblword(char *word1, char *word2,
                                  PLwdatum *wdatum, PLcword *cword);
extern bool plpgsql_parse_tripword(char *word1, char *word2, char *word3,
                                   PLwdatum *wdatum, PLcword *cword);
extern PLpgSQL_type *plpgsql_parse_wordtype(char *ident);
extern PLpgSQL_type *plpgsql_parse_cwordtype(List *idents);
extern PLpgSQL_type *plpgsql_parse_wordrowtype(char *ident);
extern PLpgSQL_type *plpgsql_parse_cwordrowtype(List *idents);
extern PLpgSQL_type *plpgsql_build_datatype(Oid typeOid, int32 typmod,
                                            Oid collation,
                                            TypeName *origtypname);
extern PLpgSQL_variable *plpgsql_build_variable(const char *refname, int lineno,
                                                PLpgSQL_type *dtype,
                                                bool add2namespace);
extern PLpgSQL_rec *plpgsql_build_record(const char *refname, int lineno,
                                         PLpgSQL_type *dtype, Oid rectypeid,
                                         bool add2namespace);
extern PLpgSQL_recfield *plpgsql_build_recfield(PLpgSQL_rec *rec,
                                                const char *fldname);
extern int  plpgsql_recognize_err_condition(const char *condname,
                                            bool allow_sqlstate);
extern PLpgSQL_condition *plpgsql_parse_err_condition(char *condname);
extern void plpgsql_adddatum(PLpgSQL_datum *newdatum);
extern int  plpgsql_add_initdatums(int **varnos);
extern void plpgsql_HashTableInit(void);

/*
 * Functions in pl_handler.c
 */
extern void _PG_init(void);

/*
 * Functions in pl_exec.c
 */
extern Datum plpgsql_exec_function(PLpgSQL_function *func,
                                   FunctionCallInfo fcinfo,
                                   EState *simple_eval_estate,
                                   ResourceOwner simple_eval_resowner,
                                   ResourceOwner procedure_resowner,
                                   bool atomic);
extern HeapTuple plpgsql_exec_trigger(PLpgSQL_function *func,
                                      TriggerData *trigdata);
extern void plpgsql_exec_event_trigger(PLpgSQL_function *func,
                                       EventTriggerData *trigdata);
extern void plpgsql_xact_cb(XactEvent event, void *arg);
extern void plpgsql_subxact_cb(SubXactEvent event, SubTransactionId mySubid,
                               SubTransactionId parentSubid, void *arg);
extern Oid  plpgsql_exec_get_datum_type(PLpgSQL_execstate *estate,
                                        PLpgSQL_datum *datum);
extern void plpgsql_exec_get_datum_type_info(PLpgSQL_execstate *estate,
                                             PLpgSQL_datum *datum,
                                             Oid *typeId, int32 *typMod,
                                             Oid *collation);

/*
 * Functions for namespace handling in pl_funcs.c
 */
extern void plpgsql_ns_init(void);
extern void plpgsql_ns_push(const char *label,
                            PLpgSQL_label_type label_type);
extern void plpgsql_ns_pop(void);
extern PLpgSQL_nsitem *plpgsql_ns_top(void);
extern void plpgsql_ns_additem(PLpgSQL_nsitem_type itemtype, int itemno, const char *name);
extern PLpgSQL_nsitem *plpgsql_ns_lookup(PLpgSQL_nsitem *ns_cur, bool localmode,
                                         const char *name1, const char *name2,
                                         const char *name3, int *names_used);
extern PLpgSQL_nsitem *plpgsql_ns_lookup_label(PLpgSQL_nsitem *ns_cur,
                                               const char *name);
extern PLpgSQL_nsitem *plpgsql_ns_find_nearest_loop(PLpgSQL_nsitem *ns_cur);

/*
 * Other functions in pl_funcs.c
 */
extern const char *plpgsql_stmt_typename(PLpgSQL_stmt *stmt);
extern const char *plpgsql_getdiag_kindname(PLpgSQL_getdiag_kind kind);
extern void plpgsql_free_function_memory(PLpgSQL_function *func);
extern void plpgsql_dumptree(PLpgSQL_function *func);

/*
 * Scanner functions in pl_scanner.c
 */
extern int  plpgsql_base_yylex(void);
extern int  plpgsql_yylex(void);
extern void plpgsql_push_back_token(int token);
extern bool plpgsql_token_is_unreserved_keyword(int token);
extern void plpgsql_append_source_text(StringInfo buf,
                                       int startlocation, int endlocation);
extern int  plpgsql_peek(void);
extern void plpgsql_peek2(int *tok1_p, int *tok2_p, int *tok1_loc,
                          int *tok2_loc);
extern int  plpgsql_scanner_errposition(int location);
extern void plpgsql_yyerror(const char *message) pg_attribute_noreturn();
extern int  plpgsql_location_to_lineno(int location);
extern int  plpgsql_latest_lineno(void);
extern void plpgsql_scanner_init(const char *str);
extern void plpgsql_scanner_finish(void);

/*
 * Externs in gram.y
 */
extern int  plpgsql_yyparse(void);

#endif                          /* PLPGSQL_H */