This patch implement the TODO [ALTER DATABASE foo OWNER TO bar].

[postgresql] / src / bin / psql / tab-complete.c

/*
 * psql - the PostgreSQL interactive terminal
 *
 * Copyright (c) 2000-2003, PostgreSQL Global Development Group
 *
 * $PostgreSQL: pgsql/src/bin/psql/tab-complete.c,v 1.107 2004/05/26 13:56:55 momjian Exp $
 */

/*----------------------------------------------------------------------
 * This file implements a somewhat more sophisticated readline "TAB
 * completion" in psql. It is not intended to be AI, to replace
 * learning SQL, or to relieve you from thinking about what you're
 * doing. Also it does not always give you all the syntactically legal
 * completions, only those that are the most common or the ones that
 * the programmer felt most like implementing.
 *
 * CAVEAT: Tab completion causes queries to be sent to the backend.
 * The number of tuples returned gets limited, in most default
 * installations to 1000, but if you still don't like this prospect,
 * you can turn off tab completion in your ~/.inputrc (or else
 * ${INPUTRC}) file so:
 *
 *       $if psql
 *       set disable-completion on
 *       $endif
 *
 * See `man 3 readline' or `info readline' for the full details. Also,
 * hence the
 *
 * BUGS:
 *
 * - If you split your queries across lines, this whole thing gets
 *       confused. (To fix this, one would have to read psql's query
 *       buffer rather than readline's line buffer, which would require
 *       some major revisions of things.)
 *
 * - Table or attribute names with spaces in it may confuse it.
 *
 * - Quotes, parenthesis, and other funny characters are not handled
 *       all that gracefully.
 *----------------------------------------------------------------------
 */

#include "postgres_fe.h"
#include "tab-complete.h"
#include "input.h"

/* If we don't have this, we might as well forget about the whole thing: */
#ifdef USE_READLINE

#include <ctype.h>
#include "libpq-fe.h"
#include "pqexpbuffer.h"
#include "common.h"
#include "settings.h"


#ifdef HAVE_RL_FILENAME_COMPLETION_FUNCTION
#define filename_completion_function rl_filename_completion_function
#else
/* missing in some header files */
extern char *filename_completion_function();
#endif

#ifdef HAVE_RL_COMPLETION_MATCHES
#define completion_matches rl_completion_matches
#endif


/*
 * This struct is used to define "schema queries", which are custom-built
 * to obtain possibly-schema-qualified names of database objects.  There is
 * enough similarity in the structure that we don't want to repeat it each
 * time.  So we put the components of each query into this struct and
 * assemble them with the common boilerplate in _complete_from_query().
 */
typedef struct SchemaQuery
{
        /*
         * Name of catalog or catalogs to be queried, with alias, eg.
         * "pg_catalog.pg_class c".  Note that "pg_namespace n" will be added.
         */
        const char *catname;
        /*
         * Selection condition --- only rows meeting this condition are candidates
         * to display.  If catname mentions multiple tables, include the
         * necessary join condition here.  For example, "c.relkind = 'r'".
         * Write NULL (not an empty string) if not needed.
         */
        const char *selcondition;
        /*
         * Visibility condition --- which rows are visible without schema
         * qualification?  For example, "pg_catalog.pg_table_is_visible(c.oid)".
         */
        const char *viscondition;
        /*
         * Namespace --- name of field to join to pg_namespace.oid.
         * For example, "c.relnamespace".
         */
        const char *namespace;
        /*
         * Result --- the appropriately-quoted name to return, in the case of
         * an unqualified name.  For example, "pg_catalog.quote_ident(c.relname)".
         */
        const char *result;
        /*
         * In some cases a different result must be used for qualified names.
         * Enter that here, or write NULL if result can be used.
         */
        const char *qualresult;
} SchemaQuery;


/* Store maximum number of records we want from database queries
 * (implemented via SELECT ... LIMIT xx).
 */
static int      completion_max_records;

/*
 * Communication variables set by COMPLETE_WITH_FOO macros and then used by
 * the completion callback functions.  Ugly but there is no better way.
 */
static const char *completion_charp;    /* to pass a string */
static const char * const *completion_charpp;   /* to pass a list of strings */
static const char *completion_info_charp;       /* to pass a second string */
static const SchemaQuery *completion_squery; /* to pass a SchemaQuery */

/* A couple of macros to ease typing. You can use these to complete the given
   string with
   1) The results from a query you pass it. (Perhaps one of those below?)
   2) The results from a schema query you pass it.
   3) The items from a null-pointer-terminated list.
   4) A string constant
   5) The list of attributes to the given table.
*/
#define COMPLETE_WITH_QUERY(query) \
do { completion_charp = query; matches = completion_matches(text, complete_from_query); } while(0)
#define COMPLETE_WITH_SCHEMA_QUERY(query,addon) \
do { completion_squery = &(query); completion_charp = addon; matches = completion_matches(text, complete_from_schema_query); } while(0)
#define COMPLETE_WITH_LIST(list) \
do { completion_charpp = list; matches = completion_matches(text, complete_from_list); } while(0)
#define COMPLETE_WITH_CONST(string) \
do { completion_charp = string; matches = completion_matches(text, complete_from_const); } while(0)
#define COMPLETE_WITH_ATTR(table) \
do {completion_charp = Query_for_list_of_attributes; completion_info_charp = table; matches = completion_matches(text, complete_from_query); } while(0)

/*
 * Assembly instructions for schema queries
 */

static const SchemaQuery Query_for_list_of_aggregates = {
        /* catname */
        "pg_catalog.pg_proc p",
        /* selcondition */
        "p.proisagg",
        /* viscondition */
        "pg_catalog.pg_function_is_visible(p.oid)",
        /* namespace */
        "p.pronamespace",
        /* result */
        "pg_catalog.quote_ident(p.proname)",
        /* qualresult */
        NULL
};

static const SchemaQuery Query_for_list_of_datatypes = {
        /* catname */
        "pg_catalog.pg_type t",
        /* selcondition --- ignore table rowtypes and array types */
        "(t.typrelid = 0 "
        " OR (SELECT c.relkind = 'c' FROM pg_catalog.pg_class c WHERE c.oid = t.typrelid)) "
        "AND t.typname !~ '^_'",
        /* viscondition */
        "pg_catalog.pg_type_is_visible(t.oid)",
        /* namespace */
        "t.typnamespace",
        /* result */
        "pg_catalog.format_type(t.oid, NULL)",
        /* qualresult */
        "pg_catalog.quote_ident(t.typname)"
};

static const SchemaQuery Query_for_list_of_domains = {
        /* catname */
        "pg_catalog.pg_type t",
        /* selcondition */
        "t.typtype = 'd'",
        /* viscondition */
        "pg_catalog.pg_type_is_visible(t.oid)",
        /* namespace */
        "t.typnamespace",
        /* result */
        "pg_catalog.quote_ident(t.typname)",
        /* qualresult */
        NULL
};

static const SchemaQuery Query_for_list_of_functions = {
        /* catname */
        "pg_catalog.pg_proc p",
        /* selcondition */
        NULL,
        /* viscondition */
        "pg_catalog.pg_function_is_visible(p.oid)",
        /* namespace */
        "p.pronamespace",
        /* result */
        "pg_catalog.quote_ident(p.proname)",
        /* qualresult */
        NULL
};

static const SchemaQuery Query_for_list_of_indexes = {
        /* catname */
        "pg_catalog.pg_class c",
        /* selcondition */
        "c.relkind IN ('i')",
        /* viscondition */
        "pg_catalog.pg_table_is_visible(c.oid)",
        /* namespace */
        "c.relnamespace",
        /* result */
        "pg_catalog.quote_ident(c.relname)",
        /* qualresult */
        NULL
};

static const SchemaQuery Query_for_list_of_sequences = {
        /* catname */
        "pg_catalog.pg_class c",
        /* selcondition */
        "c.relkind IN ('S')",
        /* viscondition */
        "pg_catalog.pg_table_is_visible(c.oid)",
        /* namespace */
        "c.relnamespace",
        /* result */
        "pg_catalog.quote_ident(c.relname)",
        /* qualresult */
        NULL
};

static const SchemaQuery Query_for_list_of_tables = {
        /* catname */
        "pg_catalog.pg_class c",
        /* selcondition */
        "c.relkind IN ('r')",
        /* viscondition */
        "pg_catalog.pg_table_is_visible(c.oid)",
        /* namespace */
        "c.relnamespace",
        /* result */
        "pg_catalog.quote_ident(c.relname)",
        /* qualresult */
        NULL
};

static const SchemaQuery Query_for_list_of_tisv = {
        /* catname */
        "pg_catalog.pg_class c",
        /* selcondition */
        "c.relkind IN ('r', 'i', 'S', 'v')",
        /* viscondition */
        "pg_catalog.pg_table_is_visible(c.oid)",
        /* namespace */
        "c.relnamespace",
        /* result */
        "pg_catalog.quote_ident(c.relname)",
        /* qualresult */
        NULL
};

static const SchemaQuery Query_for_list_of_tsv = {
        /* catname */
        "pg_catalog.pg_class c",
        /* selcondition */
        "c.relkind IN ('r', 'S', 'v')",
        /* viscondition */
        "pg_catalog.pg_table_is_visible(c.oid)",
        /* namespace */
        "c.relnamespace",
        /* result */
        "pg_catalog.quote_ident(c.relname)",
        /* qualresult */
        NULL
};

static const SchemaQuery Query_for_list_of_views = {
        /* catname */
        "pg_catalog.pg_class c",
        /* selcondition */
        "c.relkind IN ('v')",
        /* viscondition */
        "pg_catalog.pg_table_is_visible(c.oid)",
        /* namespace */
        "c.relnamespace",
        /* result */
        "pg_catalog.quote_ident(c.relname)",
        /* qualresult */
        NULL
};


/*
 * Queries to get lists of names of various kinds of things, possibly
 * restricted to names matching a partially entered name.  In these queries,
 * %s will be replaced by the text entered so far (suitably escaped to
 * become a SQL literal string).  %d will be replaced by the length of the
 * string (in unescaped form).  A second %s, if present, will be replaced
 * by a suitably-escaped version of the string provided in
 * completion_info_charp.
 *
 * Beware that the allowed sequences of %s and %d are determined by
 * _complete_from_query().
 */

#define Query_for_list_of_attributes \
"SELECT pg_catalog.quote_ident(attname) "\
"  FROM pg_catalog.pg_attribute a, pg_catalog.pg_class c "\
" WHERE c.oid = a.attrelid "\
"   AND a.attnum > 0 "\
"   AND NOT a.attisdropped "\
"   AND substring(pg_catalog.quote_ident(attname),1,%d)='%s' "\
"   AND pg_catalog.quote_ident(relname)='%s' "\
"   AND pg_catalog.pg_table_is_visible(c.oid)"

#define Query_for_list_of_databases \
"SELECT pg_catalog.quote_ident(datname) FROM pg_catalog.pg_database "\
" WHERE substring(pg_catalog.quote_ident(datname),1,%d)='%s'"

#define Query_for_list_of_encodings \
" SELECT DISTINCT pg_catalog.pg_encoding_to_char(conforencoding) "\
"   FROM pg_catalog.pg_conversion "\
"  WHERE substring(pg_catalog.pg_encoding_to_char(conforencoding),1,%d)=UPPER('%s')"

#define Query_for_list_of_languages \
"SELECT pg_catalog.quote_ident(lanname) "\
"  FROM pg_language "\
" WHERE lanname != 'internal' "\
"   AND substring(pg_catalog.quote_ident(lanname),1,%d)='%s' "

#define Query_for_list_of_schemas \
"SELECT pg_catalog.quote_ident(nspname) FROM pg_catalog.pg_namespace "\
" WHERE substring(pg_catalog.quote_ident(nspname),1,%d)='%s'"

#define Query_for_list_of_system_relations \
"SELECT pg_catalog.quote_ident(relname) "\
"  FROM pg_catalog.pg_class c, pg_catalog.pg_namespace n "\
" WHERE c.relkind IN ('r', 'v', 's', 'S') "\
"   AND substring(pg_catalog.quote_ident(relname),1,%d)='%s' "\
"   AND c.relnamespace = n.oid "\
"   AND n.nspname = 'pg_catalog'"

#define Query_for_list_of_users \
" SELECT pg_catalog.quote_ident(usename) "\
"   FROM pg_catalog.pg_user "\
"  WHERE substring(pg_catalog.quote_ident(usename),1,%d)='%s'"

/* the silly-looking length condition is just to eat up the current word */
#define Query_for_table_owning_index \
"SELECT pg_catalog.quote_ident(c1.relname) "\
"  FROM pg_catalog.pg_class c1, pg_catalog.pg_class c2, pg_catalog.pg_index i"\
" WHERE c1.oid=i.indrelid and i.indexrelid=c2.oid"\
"       and (%d = length('%s'))"\
"       and pg_catalog.quote_ident(c2.relname)='%s'"\
"       and pg_catalog.pg_table_is_visible(c2.oid)"

/*
 * This is a list of all "things" in Pgsql, which can show up after CREATE or
 * DROP; and there is also a query to get a list of them.
 */

typedef struct
{
        const char *name;
        const char *query;                      /* simple query, or NULL */
        const SchemaQuery *squery;      /* schema query, or NULL */
} pgsql_thing_t;

static const pgsql_thing_t words_after_create[] = {
        {"AGGREGATE", NULL, &Query_for_list_of_aggregates},
        {"CAST", NULL, NULL},           /* Casts have complex structures for
                                                                 * names, so skip it */
        {"CONVERSION", "SELECT pg_catalog.quote_ident(conname) FROM pg_catalog.pg_conversion WHERE substring(pg_catalog.quote_ident(conname),1,%d)='%s'"},
        {"DATABASE", Query_for_list_of_databases},
        {"DOMAIN", NULL, &Query_for_list_of_domains},
        {"FUNCTION", NULL, &Query_for_list_of_functions},
        {"GROUP", "SELECT pg_catalog.quote_ident(groname) FROM pg_catalog.pg_group WHERE substring(pg_catalog.quote_ident(groname),1,%d)='%s'"},
        {"LANGUAGE", Query_for_list_of_languages},
        {"INDEX", NULL, &Query_for_list_of_indexes},
        {"OPERATOR", NULL, NULL},       /* Querying for this is probably
                                                                 * not such a good idea. */
        {"RULE", "SELECT pg_catalog.quote_ident(rulename) FROM pg_catalog.pg_rules WHERE substring(pg_catalog.quote_ident(rulename),1,%d)='%s'"},
        {"SCHEMA", Query_for_list_of_schemas},
        {"SEQUENCE", NULL, &Query_for_list_of_sequences},
        {"TABLE", NULL, &Query_for_list_of_tables},
        {"TEMP", NULL, NULL},   /* for CREATE TEMP TABLE ... */
        {"TRIGGER", "SELECT pg_catalog.quote_ident(tgname) FROM pg_catalog.pg_trigger WHERE substring(pg_catalog.quote_ident(tgname),1,%d)='%s'"},
        {"TYPE", NULL, &Query_for_list_of_datatypes},
        {"UNIQUE", NULL, NULL}, /* for CREATE UNIQUE INDEX ... */
        {"USER", Query_for_list_of_users},
        {"VIEW", NULL, &Query_for_list_of_views},
        {NULL, NULL, NULL}                      /* end of list */
};


/* Forward declaration of functions */
static char **psql_completion(char *text, int start, int end);
static char *create_command_generator(const char *text, int state);
static char *complete_from_query(const char *text, int state);
static char *complete_from_schema_query(const char *text, int state);
static char *_complete_from_query(int is_schema_query,
                                         const char *text, int state);
static char *complete_from_const(const char *text, int state);
static char *complete_from_list(const char *text, int state);

static PGresult *exec_query(const char *query);

static char *previous_word(int point, int skip);

#if 0
static char *quote_file_name(char *text, int match_type, char *quote_pointer);
static char *dequote_file_name(char *text, char quote_char);
#endif


/* Initialize the readline library for our purposes. */
void
initialize_readline(void)
{
        rl_readline_name = (char *)pset.progname;
        rl_attempted_completion_function = (void *) psql_completion;

        rl_basic_word_break_characters = "\t\n@$><=;|&{( ";

        completion_max_records = 1000;

        /*
         * There is a variable rl_completion_query_items for this but
         * apparently it's not defined everywhere.
         */
}


/* The completion function. Acc. to readline spec this gets passed the text
   entered to far and its start and end in the readline buffer. The return value
   is some partially obscure list format that can be generated by the readline
   libraries completion_matches() function, so we don't have to worry about it.
*/
static char **
psql_completion(char *text, int start, int end)
{
        /* This is the variable we'll return. */
        char      **matches = NULL;

        /* These are going to contain some scannage of the input line. */
        char       *prev_wd,
                           *prev2_wd,
                           *prev3_wd,
                           *prev4_wd;

        static const char * const sql_commands[] = {
                "ABORT", "ALTER", "ANALYZE", "BEGIN", "CHECKPOINT", "CLOSE", "CLUSTER", "COMMENT",
                "COMMIT", "COPY", "CREATE", "DEALLOCATE", "DECLARE", "DELETE", "DROP", "EXECUTE",
                "EXPLAIN", "FETCH", "GRANT", "INSERT", "LISTEN", "LOAD", "LOCK", "MOVE", "NOTIFY",
                "PREPARE", "REINDEX", "RESET", "REVOKE", "ROLLBACK", "SELECT", "SET", "SHOW", "START",
                "TRUNCATE", "UNLISTEN", "UPDATE", "VACUUM", NULL
        };

        static const char * const pgsql_variables[] = {
                /* these SET arguments are known in gram.y */
                "CONSTRAINTS",
                "NAMES",
                "SESSION",
                "TRANSACTION",

                /*
                 * the rest should match USERSET and possibly SUSET entries in
                 * backend/utils/misc/guc.c.
                 */
                "add_missing_from",
                "australian_timezones",
                "client_encoding",
                "client_min_messages",
                "commit_delay",
                "commit_siblings",
                "cpu_index_tuple_cost",
                "cpu_operator_cost",
                "cpu_tuple_cost",
                "DateStyle",
                "deadlock_timeout",
                "debug_pretty_print",
                "debug_print_parse",
                "debug_print_plan",
                "debug_print_rewritten",
                "default_statistics_target",
                "default_transaction_isolation",
                "default_transaction_read_only",
                "default_with_oids",
                "dynamic_library_path",
                "effective_cache_size",
                "enable_hashagg",
                "enable_hashjoin",
                "enable_indexscan",
                "enable_mergejoin",
                "enable_nestloop",
                "enable_seqscan",
                "enable_sort",
                "enable_tidscan",
                "explain_pretty_print",
                "extra_float_digits",
                "from_collapse_limit",
                "fsync",
                "geqo",
                "geqo_effort",
                "geqo_generations",
                "geqo_pool_size",
                "geqo_selection_bias",
                "geqo_threshold",
                "join_collapse_limit",
                "krb_server_keyfile",
                "lc_messages",
                "lc_monetary",
                "lc_numeric",
                "lc_time",
                "log_destination",
                "log_duration",
                "log_error_verbosity",
                "log_executor_stats",
                "log_min_duration_statement",
                "log_min_error_statement",
                "log_min_messages",
                "log_parser_stats",
                "log_planner_stats",
                "log_statement",
                "log_statement_stats",
                "maintenance_work_mem",
                "max_connections",
                "max_files_per_process",
                "max_fsm_pages",
                "max_fsm_relations",
                "max_locks_per_transaction",
                "max_stack_depth",
                "password_encryption",
                "port",
                "random_page_cost",
                "regex_flavor",
                "search_path",
                "shared_buffers",
                "seed",
                "server_encoding",
                "sql_inheritance",
                "ssl",
                "statement_timeout",
                "stats_block_level",
                "stats_command_string",
                "stats_reset_on_server_start",
                "stats_row_level",
                "stats_start_collector",
                "superuser_reserved_connections",
                "syslog_facility",
                "syslog_ident",
                "TimeZone",
                "trace_notify",
                "transform_null_equals",
                "unix_socket_directory",
                "unix_socket_group",
                "unix_socket_permissions",
                "wal_buffers",
                "wal_debug",
                "wal_sync_method",
                "work_mem",
                NULL
        };

        static const char * const backslash_commands[] = {
                "\\a", "\\connect", "\\C", "\\cd", "\\copy", "\\copyright",
                "\\d", "\\da", "\\dc", "\\dC", "\\dd", "\\dD", "\\df", "\\dg", "\\di",
                "\\dl", "\\dn", "\\do", "\\dp", "\\ds", "\\dS", "\\dt", "\\dT",
                "\\dv", "\\du",
                "\\e", "\\echo", "\\encoding",
                "\\f", "\\g", "\\h", "\\help", "\\H", "\\i", "\\l",
                "\\lo_import", "\\lo_export", "\\lo_list", "\\lo_unlink",
                "\\o", "\\p", "\\pset", "\\q", "\\qecho", "\\r", "\\set", "\\t", "\\T",
                "\\timing", "\\unset", "\\x", "\\w", "\\z", "\\!", NULL
        };

        (void) end;                                     /* not used */

#ifdef HAVE_RL_COMPLETION_APPEND_CHARACTER
        rl_completion_append_character = ' ';
#endif

        /* Clear a few things. */
        completion_charp = NULL;
        completion_charpp = NULL;
        completion_info_charp = NULL;

        /*
         * Scan the input line before our current position for the last four
         * words. According to those we'll make some smart decisions on what
         * the user is probably intending to type. TODO: Use strtokx() to do
         * this.
         */
        prev_wd = previous_word(start, 0);
        prev2_wd = previous_word(start, 1);
        prev3_wd = previous_word(start, 2);
        prev4_wd = previous_word(start, 3);

        /* If a backslash command was started, continue */
        if (text[0] == '\\')
                COMPLETE_WITH_LIST(backslash_commands);

        /* If no previous word, suggest one of the basic sql commands */
        else if (!prev_wd)
                COMPLETE_WITH_LIST(sql_commands);

/* CREATE or DROP but not ALTER TABLE sth DROP */
        /* complete with something you can create or drop */
        else if (pg_strcasecmp(prev_wd, "CREATE") == 0 ||
                         (pg_strcasecmp(prev_wd, "DROP") == 0 &&
                          pg_strcasecmp(prev3_wd, "TABLE") != 0))
                matches = completion_matches(text, create_command_generator);

/* ALTER */

        /*
         * complete with what you can alter (TABLE, GROUP, USER, ...) unless
         * we're in ALTER TABLE sth ALTER
         */
        else if (pg_strcasecmp(prev_wd, "ALTER") == 0 &&
                         pg_strcasecmp(prev3_wd, "TABLE") != 0)
        {
                static const char *const list_ALTER[] =
                {"DATABASE", "GROUP", "SCHEMA", "TABLE", "TRIGGER", "USER", NULL};

                COMPLETE_WITH_LIST(list_ALTER);
        }

        /* ALTER DATABASE <name> */
        else if (pg_strcasecmp(prev3_wd, "ALTER") == 0 &&
                         pg_strcasecmp(prev2_wd, "DATABASE") == 0)
        {
                static const char *const list_ALTERDATABASE[] =
                {"RESET", "SET", "OWNER TO", "RENAME TO", NULL};

                COMPLETE_WITH_LIST(list_ALTERDATABASE);
        }
        /* ALTER TRIGGER <name>, add ON */
        else if (pg_strcasecmp(prev3_wd, "ALTER") == 0 &&
                         pg_strcasecmp(prev2_wd, "TRIGGER") == 0)
                COMPLETE_WITH_CONST("ON");

        /*
         * If we have ALTER TRIGGER <sth> ON, then add the correct tablename
         */
        else if (pg_strcasecmp(prev4_wd, "ALTER") == 0 &&
                         pg_strcasecmp(prev3_wd, "TRIGGER") == 0 &&
                         pg_strcasecmp(prev_wd, "ON") == 0)
                COMPLETE_WITH_SCHEMA_QUERY(Query_for_list_of_tables, NULL);

        /*
         * If we detect ALTER TABLE <name>, suggest either ADD, DROP, ALTER,
         * RENAME, or OWNER
         */
        else if (pg_strcasecmp(prev3_wd, "ALTER") == 0 &&
                         pg_strcasecmp(prev2_wd, "TABLE") == 0)
        {
                static const char *const list_ALTER2[] =
                {"ADD", "ALTER", "DROP", "RENAME", "OWNER TO", NULL};

                COMPLETE_WITH_LIST(list_ALTER2);
        }
        /* If we have TABLE <sth> ALTER|RENAME, provide list of columns */
        else if (pg_strcasecmp(prev3_wd, "TABLE") == 0 &&
                         (pg_strcasecmp(prev_wd, "ALTER") == 0 ||
                          pg_strcasecmp(prev_wd, "RENAME") == 0))
                COMPLETE_WITH_ATTR(prev2_wd);

        /* If we have TABLE <sth> DROP, provide COLUMN or CONSTRAINT */
        else if (pg_strcasecmp(prev3_wd, "TABLE") == 0 &&
                         pg_strcasecmp(prev_wd, "DROP") == 0)
        {
                static const char *const list_TABLEDROP[] =
                {"COLUMN", "CONSTRAINT", NULL};

                COMPLETE_WITH_LIST(list_TABLEDROP);
        }
        /* If we have TABLE <sth> DROP COLUMN, provide list of columns */
        else if (pg_strcasecmp(prev4_wd, "TABLE") == 0 &&
                         pg_strcasecmp(prev2_wd, "DROP") == 0 &&
                         pg_strcasecmp(prev_wd, "COLUMN") == 0)
                COMPLETE_WITH_ATTR(prev3_wd);

        /* complete ALTER GROUP <foo> with ADD or DROP */
        else if (pg_strcasecmp(prev3_wd, "ALTER") == 0 &&
                         pg_strcasecmp(prev2_wd, "GROUP") == 0)
        {
                static const char *const list_ALTERGROUP[] =
                {"ADD", "DROP", NULL};

                COMPLETE_WITH_LIST(list_ALTERGROUP);
        }
        /* complete ALTER GROUP <foo> ADD|DROP with USER */
        else if (pg_strcasecmp(prev4_wd, "ALTER") == 0 &&
                         pg_strcasecmp(prev3_wd, "GROUP") == 0 &&
                         (pg_strcasecmp(prev_wd, "ADD") == 0 ||
                          pg_strcasecmp(prev_wd, "DROP") == 0))
                COMPLETE_WITH_CONST("USER");
        /* complete {ALTER} GROUP <foo> ADD|DROP USER with a user name */
        else if (pg_strcasecmp(prev4_wd, "GROUP") == 0 &&
                         (pg_strcasecmp(prev2_wd, "ADD") == 0 ||
                          pg_strcasecmp(prev2_wd, "DROP") == 0) &&
                         pg_strcasecmp(prev_wd, "USER") == 0)
                COMPLETE_WITH_QUERY(Query_for_list_of_users);

/* ANALYZE */
        /* If the previous word is ANALYZE, produce list of tables. */
        else if (pg_strcasecmp(prev_wd, "ANALYZE") == 0)
                COMPLETE_WITH_SCHEMA_QUERY(Query_for_list_of_tables, NULL);
        /* If we have ANALYZE <table>, complete with semicolon. */
        else if (pg_strcasecmp(prev2_wd, "ANALYZE") == 0)
                COMPLETE_WITH_CONST(";");

/* BEGIN, COMMIT, ROLLBACK, ABORT, */
        else if (pg_strcasecmp(prev_wd, "BEGIN") == 0 ||
                 pg_strcasecmp(prev_wd, "END") == 0 ||
                 pg_strcasecmp(prev_wd, "COMMIT") == 0 ||
                 pg_strcasecmp(prev_wd, "ROLLBACK") == 0 ||
                 pg_strcasecmp(prev_wd, "ABORT") == 0)
        {
                static const char * const list_TRANS[] =
                {"WORK", "TRANSACTION", NULL};

                COMPLETE_WITH_LIST(list_TRANS);
        }
/* CLUSTER */
        /* If the previous word is CLUSTER, produce list of indexes. */
        else if (pg_strcasecmp(prev_wd, "CLUSTER") == 0)
                COMPLETE_WITH_SCHEMA_QUERY(Query_for_list_of_indexes, NULL);
        /* If we have CLUSTER <sth>, then add "ON" */
        else if (pg_strcasecmp(prev2_wd, "CLUSTER") == 0)
                COMPLETE_WITH_CONST("ON");

        /*
         * If we have CLUSTER <sth> ON, then add the correct tablename as
         * well.
         */
        else if (pg_strcasecmp(prev3_wd, "CLUSTER") == 0 &&
                         pg_strcasecmp(prev_wd, "ON") == 0)
        {
                completion_info_charp = prev2_wd;
                COMPLETE_WITH_QUERY(Query_for_table_owning_index);
        }

/* COMMENT */
        else if (pg_strcasecmp(prev_wd, "COMMENT") == 0)
                COMPLETE_WITH_CONST("ON");
        else if (pg_strcasecmp(prev2_wd, "COMMENT") == 0 &&
                         pg_strcasecmp(prev_wd, "ON") == 0)
        {
                static const char *const list_COMMENT[] =
                {"DATABASE", "INDEX", "RULE", "SCHEMA", "SEQUENCE", "TABLE",
                 "TYPE", "VIEW", "COLUMN", "AGGREGATE", "FUNCTION", "OPERATOR",
                 "TRIGGER", "CONSTRAINT", "DOMAIN", NULL};

                COMPLETE_WITH_LIST(list_COMMENT);
        }
        else if (pg_strcasecmp(prev4_wd, "COMMENT") == 0 &&
                         pg_strcasecmp(prev3_wd, "ON") == 0)
                COMPLETE_WITH_CONST("IS");

/* COPY */

        /*
         * If we have COPY [BINARY] (which you'd have to type yourself), offer
         * list of tables (Also cover the analogous backslash command)
         */
        else if (pg_strcasecmp(prev_wd, "COPY") == 0 ||
                         pg_strcasecmp(prev_wd, "\\copy") == 0 ||
                         (pg_strcasecmp(prev2_wd, "COPY") == 0 &&
                          pg_strcasecmp(prev_wd, "BINARY") == 0))
                COMPLETE_WITH_SCHEMA_QUERY(Query_for_list_of_tables, NULL);
        /* If we have COPY|BINARY <sth>, complete it with "TO" or "FROM" */
        else if (pg_strcasecmp(prev2_wd, "COPY") == 0 ||
                         pg_strcasecmp(prev2_wd, "\\copy") == 0 ||
                         pg_strcasecmp(prev2_wd, "BINARY") == 0)
        {
                static const char *const list_FROMTO[] =
                {"FROM", "TO", NULL};

                COMPLETE_WITH_LIST(list_FROMTO);
        }

/* CREATE INDEX */
        /* First off we complete CREATE UNIQUE with "INDEX" */
        else if (pg_strcasecmp(prev2_wd, "CREATE") == 0 &&
                         pg_strcasecmp(prev_wd, "UNIQUE") == 0)
                COMPLETE_WITH_CONST("INDEX");
        /* If we have CREATE|UNIQUE INDEX <sth>, then add "ON" */
        else if (pg_strcasecmp(prev2_wd, "INDEX") == 0 &&
                         (pg_strcasecmp(prev3_wd, "CREATE") == 0 ||
                          pg_strcasecmp(prev3_wd, "UNIQUE") == 0))
                COMPLETE_WITH_CONST("ON");
        /* Complete ... INDEX <name> ON with a list of tables  */
        else if (pg_strcasecmp(prev3_wd, "INDEX") == 0 &&
                         pg_strcasecmp(prev_wd, "ON") == 0)
                COMPLETE_WITH_SCHEMA_QUERY(Query_for_list_of_tables, NULL);

        /*
         * Complete INDEX <name> ON <table> with a list of table columns
         * (which should really be in parens)
         */
        else if (pg_strcasecmp(prev4_wd, "INDEX") == 0 &&
                         pg_strcasecmp(prev2_wd, "ON") == 0)
                COMPLETE_WITH_ATTR(prev_wd);
        /* same if you put in USING */
        else if (pg_strcasecmp(prev4_wd, "ON") == 0 &&
                         pg_strcasecmp(prev2_wd, "USING") == 0)
                COMPLETE_WITH_ATTR(prev3_wd);
        /* Complete USING with an index method */
        else if (pg_strcasecmp(prev_wd, "USING") == 0)
        {
                static const char *const index_mth[] =
                {"BTREE", "RTREE", "HASH", "GIST", NULL};

                COMPLETE_WITH_LIST(index_mth);
        }

/* CREATE RULE */
        /* Complete "CREATE RULE <sth>" with "AS" */
        else if (pg_strcasecmp(prev3_wd, "CREATE") == 0 &&
                         pg_strcasecmp(prev2_wd, "RULE") == 0)
                COMPLETE_WITH_CONST("AS");
        /* Complete "CREATE RULE <sth> AS with "ON" */
        else if (pg_strcasecmp(prev4_wd, "CREATE") == 0 &&
                         pg_strcasecmp(prev3_wd, "RULE") == 0 &&
                         pg_strcasecmp(prev_wd, "AS") == 0)
                COMPLETE_WITH_CONST("ON");
        /* Complete "RULE * AS ON" with SELECT|UPDATE|DELETE|INSERT */
        else if (pg_strcasecmp(prev4_wd, "RULE") == 0 &&
                         pg_strcasecmp(prev2_wd, "AS") == 0 &&
                         pg_strcasecmp(prev_wd, "ON") == 0)
        {
                static const char *const rule_events[] =
                {"SELECT", "UPDATE", "INSERT", "DELETE", NULL};

                COMPLETE_WITH_LIST(rule_events);
        }
        /* Complete "AS ON <sth with a 'T' :)>" with a "TO" */
        else if (pg_strcasecmp(prev3_wd, "AS") == 0 &&
                         pg_strcasecmp(prev2_wd, "ON") == 0 &&
                         (toupper((unsigned char) prev_wd[4]) == 'T' ||
                          toupper((unsigned char) prev_wd[5]) == 'T'))
                COMPLETE_WITH_CONST("TO");
        /* Complete "AS ON <sth> TO" with a table name */
        else if (pg_strcasecmp(prev4_wd, "AS") == 0 &&
                         pg_strcasecmp(prev3_wd, "ON") == 0 &&
                         pg_strcasecmp(prev_wd, "TO") == 0)
                COMPLETE_WITH_SCHEMA_QUERY(Query_for_list_of_tables, NULL);

/* CREATE TABLE */
        /* Complete CREATE TEMP with "TABLE" */
        else if (pg_strcasecmp(prev2_wd, "CREATE") == 0 &&
                         pg_strcasecmp(prev_wd, "TEMP") == 0)
                COMPLETE_WITH_CONST("TABLE");

/* CREATE TRIGGER */
        /* is on the agenda . . . */

/* CREATE VIEW */
        /* Complete "CREATE VIEW <name>" with "AS" */
        else if (pg_strcasecmp(prev3_wd, "CREATE") == 0 &&
                         pg_strcasecmp(prev2_wd, "VIEW") == 0)
                COMPLETE_WITH_CONST("AS");
        /* Complete "CREATE VIEW <sth> AS with "SELECT" */
        else if (pg_strcasecmp(prev4_wd, "CREATE") == 0 &&
                         pg_strcasecmp(prev3_wd, "VIEW") == 0 &&
                         pg_strcasecmp(prev_wd, "AS") == 0)
                COMPLETE_WITH_CONST("SELECT");

/* DELETE */

        /*
         * Complete DELETE with FROM (only if the word before that is not "ON"
         * (cf. rules) or "BEFORE" or "AFTER" (cf. triggers) or GRANT)
         */
        else if (pg_strcasecmp(prev_wd, "DELETE") == 0 &&
                         !(pg_strcasecmp(prev2_wd, "ON") == 0 ||
                           pg_strcasecmp(prev2_wd, "GRANT") == 0 ||
                           pg_strcasecmp(prev2_wd, "BEFORE") == 0 ||
                           pg_strcasecmp(prev2_wd, "AFTER") == 0))
                COMPLETE_WITH_CONST("FROM");
        /* Complete DELETE FROM with a list of tables */
        else if (pg_strcasecmp(prev2_wd, "DELETE") == 0 &&
                         pg_strcasecmp(prev_wd, "FROM") == 0)
                COMPLETE_WITH_SCHEMA_QUERY(Query_for_list_of_tables, NULL);
        /* Complete DELETE FROM <table> with "WHERE" (perhaps a safe idea?) */
        else if (pg_strcasecmp(prev3_wd, "DELETE") == 0 &&
                         pg_strcasecmp(prev2_wd, "FROM") == 0)
                COMPLETE_WITH_CONST("WHERE");

/* EXPLAIN */

        /*
         * Complete EXPLAIN [VERBOSE] (which you'd have to type yourself) with
         * the list of SQL commands
         */
        else if (pg_strcasecmp(prev_wd, "EXPLAIN") == 0 ||
                         (pg_strcasecmp(prev2_wd, "EXPLAIN") == 0 &&
                          pg_strcasecmp(prev_wd, "VERBOSE") == 0))
                COMPLETE_WITH_LIST(sql_commands);

/* FETCH && MOVE */
        /* Complete FETCH with one of FORWARD, BACKWARD, RELATIVE */
        else if (pg_strcasecmp(prev_wd, "FETCH") == 0 ||
                         pg_strcasecmp(prev_wd, "MOVE") == 0)
        {
                static const char * const list_FETCH1[] =
                {"FORWARD", "BACKWARD", "RELATIVE", NULL};

                COMPLETE_WITH_LIST(list_FETCH1);
        }
        /* Complete FETCH <sth> with one of ALL, NEXT, PRIOR */
        else if (pg_strcasecmp(prev2_wd, "FETCH") == 0 ||
                         pg_strcasecmp(prev2_wd, "MOVE") == 0)
        {
                static const char * const list_FETCH2[] =
                {"ALL", "NEXT", "PRIOR", NULL};

                COMPLETE_WITH_LIST(list_FETCH2);
        }

        /*
         * Complete FETCH <sth1> <sth2> with "FROM" or "TO". (Is there a
         * difference? If not, remove one.)
         */
        else if (pg_strcasecmp(prev3_wd, "FETCH") == 0 ||
                         pg_strcasecmp(prev3_wd, "MOVE") == 0)
        {
                static const char * const list_FROMTO[] =
                {"FROM", "TO", NULL};

                COMPLETE_WITH_LIST(list_FROMTO);
        }

/* GRANT && REVOKE*/
        /* Complete GRANT/REVOKE with a list of privileges */
        else if (pg_strcasecmp(prev_wd, "GRANT") == 0 ||
                         pg_strcasecmp(prev_wd, "REVOKE") == 0)
        {
                static const char * const list_privileg[] =
                {"SELECT", "INSERT", "UPDATE", "DELETE", "RULE", "REFERENCES",
                 "TRIGGER", "CREATE", "TEMPORARY", "EXECUTE", "USAGE", "ALL", NULL};

                COMPLETE_WITH_LIST(list_privileg);
        }
        /* Complete GRANT/REVOKE <sth> with "ON" */
        else if (pg_strcasecmp(prev2_wd, "GRANT") == 0 ||
                         pg_strcasecmp(prev2_wd, "REVOKE") == 0)
                COMPLETE_WITH_CONST("ON");

        /*
         * Complete GRANT/REVOKE <sth> ON with a list of tables, views,
         * sequences, and indexes
         *
         * keywords DATABASE, FUNCTION, LANGUAGE, SCHEMA added to query result
         * via UNION; seems to work intuitively
         *
         * Note: GRANT/REVOKE can get quite complex; tab-completion as
         * implemented here will only work if the privilege list contains
         * exactly one privilege
         */
        else if ((pg_strcasecmp(prev3_wd, "GRANT") == 0 ||
                          pg_strcasecmp(prev3_wd, "REVOKE") == 0) &&
                         pg_strcasecmp(prev_wd, "ON") == 0)
                COMPLETE_WITH_SCHEMA_QUERY(Query_for_list_of_tsv,
                                                                   " UNION SELECT 'DATABASE'"
                                                                   " UNION SELECT 'FUNCTION'"
                                                                   " UNION SELECT 'LANGUAGE'"
                                                                   " UNION SELECT 'SCHEMA'");

        /* Complete "GRANT/REVOKE * ON * " with "TO" */
        else if ((pg_strcasecmp(prev4_wd, "GRANT") == 0 ||
                          pg_strcasecmp(prev4_wd, "REVOKE") == 0) &&
                         pg_strcasecmp(prev2_wd, "ON") == 0)
        {
                if (pg_strcasecmp(prev_wd, "DATABASE") == 0)
                        COMPLETE_WITH_QUERY(Query_for_list_of_databases);
                else if (pg_strcasecmp(prev_wd, "FUNCTION") == 0)
                        COMPLETE_WITH_SCHEMA_QUERY(Query_for_list_of_functions, NULL);
                else if (pg_strcasecmp(prev_wd, "LANGUAGE") == 0)
                        COMPLETE_WITH_QUERY(Query_for_list_of_languages);
                else if (pg_strcasecmp(prev_wd, "SCHEMA") == 0)
                        COMPLETE_WITH_QUERY(Query_for_list_of_schemas);
                else
                        COMPLETE_WITH_CONST("TO");
        }

        /*
         * TODO: to complete with user name we need prev5_wd -- wait for a
         * more general solution there same for GRANT <sth> ON { DATABASE |
         * FUNCTION | LANGUAGE | SCHEMA } xxx TO
         */

/* INSERT */
        /* Complete INSERT with "INTO" */
        else if (pg_strcasecmp(prev_wd, "INSERT") == 0)
                COMPLETE_WITH_CONST("INTO");
        /* Complete INSERT INTO with table names */
        else if (pg_strcasecmp(prev2_wd, "INSERT") == 0 &&
                         pg_strcasecmp(prev_wd, "INTO") == 0)
                COMPLETE_WITH_SCHEMA_QUERY(Query_for_list_of_tables, NULL);
        /* Complete "INSERT INTO <table> (" with attribute names */
        else if (rl_line_buffer[start - 1] == '(' &&
                         pg_strcasecmp(prev3_wd, "INSERT") == 0 &&
                         pg_strcasecmp(prev2_wd, "INTO") == 0)
                COMPLETE_WITH_ATTR(prev_wd);

        /*
         * Complete INSERT INTO <table> with "VALUES" or "SELECT" or "DEFAULT
         * VALUES"
         */
        else if (pg_strcasecmp(prev3_wd, "INSERT") == 0 &&
                         pg_strcasecmp(prev2_wd, "INTO") == 0)
        {
                static const char * const list_INSERT[] =
                {"DEFAULT VALUES", "SELECT", "VALUES", NULL};

                COMPLETE_WITH_LIST(list_INSERT);
        }
        /* Complete INSERT INTO <table> (attribs) with "VALUES" or "SELECT" */
        else if (pg_strcasecmp(prev4_wd, "INSERT") == 0 &&
                         pg_strcasecmp(prev3_wd, "INTO") == 0 &&
                         prev_wd[strlen(prev_wd) - 1] == ')')
        {
                static const char * const list_INSERT[] =
                {"SELECT", "VALUES", NULL};

                COMPLETE_WITH_LIST(list_INSERT);
        }

        /* Insert an open parenthesis after "VALUES" */
        else if (pg_strcasecmp(prev_wd, "VALUES") == 0 &&
                         pg_strcasecmp(prev2_wd, "DEFAULT") != 0)
                COMPLETE_WITH_CONST("(");

/* LOCK */
        /* Complete LOCK [TABLE] with a list of tables */
        else if (pg_strcasecmp(prev_wd, "LOCK") == 0 ||
                         (pg_strcasecmp(prev_wd, "TABLE") == 0 &&
                          pg_strcasecmp(prev2_wd, "LOCK") == 0))
                COMPLETE_WITH_SCHEMA_QUERY(Query_for_list_of_tables, NULL);

        /* For the following, handle the case of a single table only for now */

        /* Complete LOCK [TABLE] <table> with "IN" */
        else if ((pg_strcasecmp(prev2_wd, "LOCK") == 0 &&
                          pg_strcasecmp(prev_wd, "TABLE")) ||
                         (pg_strcasecmp(prev2_wd, "TABLE") == 0 &&
                          pg_strcasecmp(prev3_wd, "LOCK") == 0))
                COMPLETE_WITH_CONST("IN");

        /* Complete LOCK [TABLE] <table> IN with a lock mode */
        else if (pg_strcasecmp(prev_wd, "IN") == 0 &&
                         (pg_strcasecmp(prev3_wd, "LOCK") == 0 ||
                          (pg_strcasecmp(prev3_wd, "TABLE") == 0 &&
                           pg_strcasecmp(prev4_wd, "LOCK") == 0)))
        {
                static const char * const lock_modes[] =
                {"ACCESS SHARE MODE",
                 "ROW SHARE MODE", "ROW EXCLUSIVE MODE",
                 "SHARE UPDATE EXCLUSIVE MODE", "SHARE MODE",
                 "SHARE ROW EXCLUSIVE MODE",
                 "EXCLUSIVE MODE", "ACCESS EXCLUSIVE MODE", NULL};

                COMPLETE_WITH_LIST(lock_modes);
        }

/* NOTIFY */
        else if (pg_strcasecmp(prev_wd, "NOTIFY") == 0)
                COMPLETE_WITH_QUERY("SELECT pg_catalog.quote_ident(relname) FROM pg_catalog.pg_listener WHERE substring(pg_catalog.quote_ident(relname),1,%d)='%s'");

/* REINDEX */
        else if (pg_strcasecmp(prev_wd, "REINDEX") == 0)
        {
                static const char * const list_REINDEX[] =
                {"TABLE", "DATABASE", "INDEX", NULL};

                COMPLETE_WITH_LIST(list_REINDEX);
        }
        else if (pg_strcasecmp(prev2_wd, "REINDEX") == 0)
        {
                if (pg_strcasecmp(prev_wd, "TABLE") == 0)
                        COMPLETE_WITH_SCHEMA_QUERY(Query_for_list_of_tables, NULL);
                else if (pg_strcasecmp(prev_wd, "DATABASE") == 0)
                        COMPLETE_WITH_QUERY(Query_for_list_of_databases);
                else if (pg_strcasecmp(prev_wd, "INDEX") == 0)
                        COMPLETE_WITH_SCHEMA_QUERY(Query_for_list_of_indexes, NULL);
        }

/* SELECT */
        /* naah . . . */

/* SET, RESET, SHOW */
        /* Complete with a variable name */
        else if ((pg_strcasecmp(prev_wd, "SET") == 0 &&
                          pg_strcasecmp(prev3_wd, "UPDATE") != 0) ||
                         pg_strcasecmp(prev_wd, "RESET") == 0 ||
                         pg_strcasecmp(prev_wd, "SHOW") == 0)
                COMPLETE_WITH_LIST(pgsql_variables);
        /* Complete "SET TRANSACTION" */
        else if ((pg_strcasecmp(prev2_wd, "SET") == 0 &&
                          pg_strcasecmp(prev_wd, "TRANSACTION") == 0)
                         || (pg_strcasecmp(prev2_wd, "START") == 0
                                 && pg_strcasecmp(prev_wd, "TRANSACTION") == 0)
                         || (pg_strcasecmp(prev2_wd, "BEGIN") == 0
                                 && pg_strcasecmp(prev_wd, "WORK") == 0)
                         || (pg_strcasecmp(prev2_wd, "BEGIN") == 0
                                 && pg_strcasecmp(prev_wd, "TRANSACTION") == 0)
                         || (pg_strcasecmp(prev4_wd, "SESSION") == 0
                                 && pg_strcasecmp(prev3_wd, "CHARACTERISTICS") == 0
                                 && pg_strcasecmp(prev2_wd, "AS") == 0
                                 && pg_strcasecmp(prev_wd, "TRANSACTION") == 0))
        {
                static const char * const my_list[] =
                {"ISOLATION", "READ", NULL};

                COMPLETE_WITH_LIST(my_list);
        }
        else if ((pg_strcasecmp(prev3_wd, "SET") == 0
                          || pg_strcasecmp(prev3_wd, "START") == 0
                          || (pg_strcasecmp(prev4_wd, "CHARACTERISTICS") == 0
                                  && pg_strcasecmp(prev3_wd, "AS") == 0))
                         && pg_strcasecmp(prev2_wd, "TRANSACTION") == 0
                         && pg_strcasecmp(prev_wd, "ISOLATION") == 0)
                COMPLETE_WITH_CONST("LEVEL");
        else if ((pg_strcasecmp(prev4_wd, "SET") == 0
                          || pg_strcasecmp(prev4_wd, "START") == 0
                          || pg_strcasecmp(prev4_wd, "AS") == 0)
                         && pg_strcasecmp(prev3_wd, "TRANSACTION") == 0
                         && pg_strcasecmp(prev2_wd, "ISOLATION") == 0
                         && pg_strcasecmp(prev_wd, "LEVEL") == 0)
        {
                static const char * const my_list[] =
                {"READ", "REPEATABLE", "SERIALIZABLE", NULL};

                COMPLETE_WITH_LIST(my_list);
        }
        else if (pg_strcasecmp(prev4_wd, "TRANSACTION") == 0 &&
                         pg_strcasecmp(prev3_wd, "ISOLATION") == 0 &&
                         pg_strcasecmp(prev2_wd, "LEVEL") == 0 &&
                         pg_strcasecmp(prev_wd, "READ") == 0)
        {
                static const char * const my_list[] =
                {"UNCOMMITTED", "COMMITTED", NULL};

                COMPLETE_WITH_LIST(my_list);
        }
        else if (pg_strcasecmp(prev4_wd, "TRANSACTION") == 0 &&
                         pg_strcasecmp(prev3_wd, "ISOLATION") == 0 &&
                         pg_strcasecmp(prev2_wd, "LEVEL") == 0 &&
                         pg_strcasecmp(prev_wd, "REPEATABLE") == 0)
                COMPLETE_WITH_CONST("READ");
        else if ((pg_strcasecmp(prev3_wd, "SET") == 0 ||
                          pg_strcasecmp(prev3_wd, "AS") == 0) &&
                         pg_strcasecmp(prev2_wd, "TRANSACTION") == 0 &&
                         pg_strcasecmp(prev_wd, "READ") == 0)
        {
                static const char * const my_list[] =
                {"ONLY", "WRITE", NULL};

                COMPLETE_WITH_LIST(my_list);
        }
        /* Complete SET CONSTRAINTS <foo> with DEFERRED|IMMEDIATE */
        else if (pg_strcasecmp(prev3_wd, "SET") == 0 &&
                         pg_strcasecmp(prev2_wd, "CONSTRAINTS") == 0)
        {
                static const char * const constraint_list[] =
                {"DEFERRED", "IMMEDIATE", NULL};

                COMPLETE_WITH_LIST(constraint_list);
        }
        /* Complete SET SESSION with AUTHORIZATION or CHARACTERISTICS... */
        else if (pg_strcasecmp(prev2_wd, "SET") == 0 &&
                         pg_strcasecmp(prev_wd, "SESSION") == 0)
        {
                static const char * const my_list[] =
                {"AUTHORIZATION", "CHARACTERISTICS AS TRANSACTION", NULL};

                COMPLETE_WITH_LIST(my_list);
        }
        /* Complete SET SESSION AUTHORIZATION with username */
        else if (pg_strcasecmp(prev3_wd, "SET") == 0
                         && pg_strcasecmp(prev2_wd, "SESSION") == 0
                         && pg_strcasecmp(prev_wd, "AUTHORIZATION") == 0)
                COMPLETE_WITH_QUERY(Query_for_list_of_users);
        /* Complete SET <var> with "TO" */
        else if (pg_strcasecmp(prev2_wd, "SET") == 0 &&
                         pg_strcasecmp(prev4_wd, "UPDATE") != 0)
                COMPLETE_WITH_CONST("TO");
        /* Suggest possible variable values */
        else if (pg_strcasecmp(prev3_wd, "SET") == 0 &&
                   (pg_strcasecmp(prev_wd, "TO") == 0 || strcmp(prev_wd, "=") == 0))
        {
                if (pg_strcasecmp(prev2_wd, "DateStyle") == 0)
                {
                        static const char * const my_list[] =
                        {"ISO", "SQL", "Postgres", "German",
                         "YMD", "DMY", "MDY",
                         "US", "European", "NonEuropean",
                         "DEFAULT", NULL};

                        COMPLETE_WITH_LIST(my_list);
                }
                else if (pg_strcasecmp(prev2_wd, "GEQO") == 0)
                {
                        static const char * const my_list[] =
                        {"ON", "OFF", "DEFAULT", NULL};

                        COMPLETE_WITH_LIST(my_list);
                }
                else
                {
                        static const char * const my_list[] =
                        {"DEFAULT", NULL};

                        COMPLETE_WITH_LIST(my_list);
                }
        }

/* START TRANSACTION */
        else if (pg_strcasecmp(prev_wd, "START") == 0)
                COMPLETE_WITH_CONST("TRANSACTION");

/* TRUNCATE */
        else if (pg_strcasecmp(prev_wd, "TRUNCATE") == 0)
                COMPLETE_WITH_SCHEMA_QUERY(Query_for_list_of_tables, NULL);

/* UNLISTEN */
        else if (pg_strcasecmp(prev_wd, "UNLISTEN") == 0)
                COMPLETE_WITH_QUERY("SELECT pg_catalog.quote_ident(relname) FROM pg_catalog.pg_listener WHERE substring(pg_catalog.quote_ident(relname),1,%d)='%s' UNION SELECT '*'");

/* UPDATE */
        /* If prev. word is UPDATE suggest a list of tables */
        else if (pg_strcasecmp(prev_wd, "UPDATE") == 0)
                COMPLETE_WITH_SCHEMA_QUERY(Query_for_list_of_tables, NULL);
        /* Complete UPDATE <table> with "SET" */
        else if (pg_strcasecmp(prev2_wd, "UPDATE") == 0)
                COMPLETE_WITH_CONST("SET");

        /*
         * If the previous word is SET (and it wasn't caught above as the
         * _first_ word) the word before it was (hopefully) a table name and
         * we'll now make a list of attributes.
         */
        else if (pg_strcasecmp(prev_wd, "SET") == 0)
                COMPLETE_WITH_ATTR(prev2_wd);

/* VACUUM */
        else if (pg_strcasecmp(prev_wd, "VACUUM") == 0)
                COMPLETE_WITH_SCHEMA_QUERY(Query_for_list_of_tables,
                                                                   " UNION SELECT 'FULL'"
                                                                   " UNION SELECT 'ANALYZE'"
                                                                   " UNION SELECT 'VERBOSE'");
        else if (pg_strcasecmp(prev2_wd, "VACUUM") == 0 &&
                         (pg_strcasecmp(prev_wd, "FULL") == 0 ||
                          pg_strcasecmp(prev_wd, "ANALYZE") == 0 ||
                          pg_strcasecmp(prev_wd, "VERBOSE") == 0))
                COMPLETE_WITH_SCHEMA_QUERY(Query_for_list_of_tables, NULL);

/* WHERE */
        /* Simple case of the word before the where being the table name */
        else if (pg_strcasecmp(prev_wd, "WHERE") == 0)
                COMPLETE_WITH_ATTR(prev2_wd);

/* ... FROM ... */
/* TODO: also include SRF ? */
        else if (pg_strcasecmp(prev_wd, "FROM") == 0)
                COMPLETE_WITH_SCHEMA_QUERY(Query_for_list_of_tsv, NULL);


/* Backslash commands */
/* TODO:  \dc \dd \dl */
        else if (strcmp(prev_wd, "\\connect") == 0 || strcmp(prev_wd, "\\c") == 0)
                COMPLETE_WITH_QUERY(Query_for_list_of_databases);
        else if (strcmp(prev_wd, "\\d") == 0 || strcmp(prev_wd, "\\d+") == 0)
                COMPLETE_WITH_SCHEMA_QUERY(Query_for_list_of_tisv, NULL);
        else if (strcmp(prev_wd, "\\da") == 0)
                COMPLETE_WITH_SCHEMA_QUERY(Query_for_list_of_aggregates, NULL);
        else if (strcmp(prev_wd, "\\dD") == 0)
                COMPLETE_WITH_SCHEMA_QUERY(Query_for_list_of_domains, NULL);
        else if (strcmp(prev_wd, "\\df") == 0 || strcmp(prev_wd, "\\df+") == 0)
                COMPLETE_WITH_SCHEMA_QUERY(Query_for_list_of_functions, NULL);
        else if (strcmp(prev_wd, "\\di") == 0 || strcmp(prev_wd, "\\di+") == 0)
                COMPLETE_WITH_SCHEMA_QUERY(Query_for_list_of_indexes, NULL);
        else if (strcmp(prev_wd, "\\dn") == 0)
                COMPLETE_WITH_QUERY(Query_for_list_of_schemas);
        else if (strcmp(prev_wd, "\\dp") == 0 || strcmp(prev_wd, "\\z") == 0)
                COMPLETE_WITH_SCHEMA_QUERY(Query_for_list_of_tsv, NULL);
        else if (strcmp(prev_wd, "\\ds") == 0 || strcmp(prev_wd, "\\ds+") == 0)
                COMPLETE_WITH_SCHEMA_QUERY(Query_for_list_of_sequences, NULL);
        else if (strcmp(prev_wd, "\\dS") == 0 || strcmp(prev_wd, "\\dS+") == 0)
                COMPLETE_WITH_QUERY(Query_for_list_of_system_relations);
        else if (strcmp(prev_wd, "\\dt") == 0 || strcmp(prev_wd, "\\dt+") == 0)
                COMPLETE_WITH_SCHEMA_QUERY(Query_for_list_of_tables, NULL);
        else if (strcmp(prev_wd, "\\dT") == 0 || strcmp(prev_wd, "\\dT+") == 0)
                COMPLETE_WITH_SCHEMA_QUERY(Query_for_list_of_datatypes, NULL);
        else if (strcmp(prev_wd, "\\du") == 0)
                COMPLETE_WITH_QUERY(Query_for_list_of_users);
        else if (strcmp(prev_wd, "\\dv") == 0 || strcmp(prev_wd, "\\dv+") == 0)
                COMPLETE_WITH_SCHEMA_QUERY(Query_for_list_of_views, NULL);
        else if (strcmp(prev_wd, "\\encoding") == 0)
                COMPLETE_WITH_QUERY(Query_for_list_of_encodings);
        else if (strcmp(prev_wd, "\\h") == 0 || strcmp(prev_wd, "\\help") == 0)
                COMPLETE_WITH_LIST(sql_commands);
        else if (strcmp(prev_wd, "\\pset") == 0)
        {
                static const char * const my_list[] =
                {"format", "border", "expanded",
                 "null", "fieldsep", "tuples_only", "title", "tableattr", "pager",
                 "recordsep", NULL};

                COMPLETE_WITH_LIST(my_list);
        }
        else if (strcmp(prev_wd, "\\cd") == 0 ||
                 strcmp(prev_wd, "\\e") == 0 || strcmp(prev_wd, "\\edit") == 0 ||
                         strcmp(prev_wd, "\\g") == 0 ||
                         strcmp(prev_wd, "\\i") == 0 || strcmp(prev_wd, "\\include") == 0 ||
                  strcmp(prev_wd, "\\o") == 0 || strcmp(prev_wd, "\\out") == 0 ||
                         strcmp(prev_wd, "\\s") == 0 ||
                   strcmp(prev_wd, "\\w") == 0 || strcmp(prev_wd, "\\write") == 0
                )
                matches = completion_matches(text, filename_completion_function);


        /*
         * Finally, we look through the list of "things", such as TABLE, INDEX
         * and check if that was the previous word. If so, execute the query
         * to get a list of them.
         */
        else
        {
                int                     i;

                for (i = 0; words_after_create[i].name; i++)
                {
                        if (pg_strcasecmp(prev_wd, words_after_create[i].name) == 0)
                        {
                                if (words_after_create[i].query)
                                        COMPLETE_WITH_QUERY(words_after_create[i].query);
                                else if (words_after_create[i].squery)
                                        COMPLETE_WITH_SCHEMA_QUERY(*words_after_create[i].squery,
                                                                                           NULL);
                                break;
                        }
                }
        }

        /*
         * If we still don't have anything to match we have to fabricate some
         * sort of default list. If we were to just return NULL, readline
         * automatically attempts filename completion, and that's usually no
         * good.
         */
        if (matches == NULL)
        {
                COMPLETE_WITH_CONST("");
#ifdef HAVE_RL_COMPLETION_APPEND_CHARACTER
                rl_completion_append_character = '\0';
#endif
        }

        /* free storage */
        free(prev_wd);
        free(prev2_wd);
        free(prev3_wd);
        free(prev4_wd);

        /* Return our Grand List O' Matches */
        return matches;
}



/* GENERATOR FUNCTIONS

   These functions do all the actual work of completing the input. They get
   passed the text so far and the count how many times they have been called so
   far with the same text.
   If you read the above carefully, you'll see that these don't get called
   directly but through the readline interface.
   The return value is expected to be the full completion of the text, going
   through a list each time, or NULL if there are no more matches. The string
   will be free()'d by readline, so you must run it through strdup() or
   something of that sort.
*/

/* This one gives you one from a list of things you can put after CREATE or DROP
   as defined above.
*/
static char *
create_command_generator(const char *text, int state)
{
        static int      list_index,
                                string_length;
        const char *name;

        /* If this is the first time for this completion, init some values */
        if (state == 0)
        {
                list_index = 0;
                string_length = strlen(text);
        }

        /* find something that matches */
        while ((name = words_after_create[list_index++].name))
                if (pg_strncasecmp(name, text, string_length) == 0)
                        return pg_strdup(name);

        /* if nothing matches, return NULL */
        return NULL;
}


/* The following two functions are wrappers for _complete_from_query */

static char *
complete_from_query(const char *text, int state)
{
        return _complete_from_query(0, text, state);
}

static char *
complete_from_schema_query(const char *text, int state)
{
        return _complete_from_query(1, text, state);
}


/* This creates a list of matching things, according to a query pointed to
   by completion_charp.
   The query can be one of two kinds:
   - A simple query which must contain a %d and a %s, which will be replaced
   by the string length of the text and the text itself. The query may also
   have another %s in it, which will be replaced by the value of
   completion_info_charp.
         or:
   - A schema query used for completion of both schema and relation names;
   these are more complex and must contain in the following order:
         %d %s %d %s %d %s %s %d %s
   where %d is the string length of the text and %s the text itself.

   It is assumed that strings should be escaped to become SQL literals
   (that is, what is in the query is actually ... '%s' ...)

   See top of file for examples of both kinds of query.
*/

static char *
_complete_from_query(int is_schema_query, const char *text, int state)
{
        static int      list_index,
                                string_length;
        static PGresult *result = NULL;

        /*
         * If this is the first time for this completion, we fetch a list of
         * our "things" from the backend.
         */
        if (state == 0)
        {
                PQExpBufferData query_buffer;
                char       *e_text;
                char       *e_info_charp;

                list_index = 0;
                string_length = strlen(text);

                /* Free any prior result */
                PQclear(result);
                result = NULL;

                /* Set up suitably-escaped copies of textual inputs */
                if (text)
                {
                        e_text = pg_malloc(strlen(text) * 2 + 1);
                        PQescapeString(e_text, text, strlen(text));
                }
                else
                        e_text = NULL;

                if (completion_info_charp)
                {
                        size_t charp_len;

                        charp_len = strlen(completion_info_charp);
                        e_info_charp = pg_malloc(charp_len * 2 + 1);
                        PQescapeString(e_info_charp, completion_info_charp,
                                                   charp_len);
                }
                else
                        e_info_charp = NULL;

                initPQExpBuffer(&query_buffer);

                if (is_schema_query)
                {
                        /* completion_squery gives us the pieces to assemble */
                        const char *qualresult = completion_squery->qualresult;

                        if (qualresult == NULL)
                                qualresult = completion_squery->result;

                        /* Get unqualified names matching the input-so-far */
                        appendPQExpBuffer(&query_buffer, "SELECT %s FROM %s WHERE ",
                                                          completion_squery->result,
                                                          completion_squery->catname);
                        if (completion_squery->selcondition)
                                appendPQExpBuffer(&query_buffer, "%s AND ",
                                                                  completion_squery->selcondition);
                        appendPQExpBuffer(&query_buffer, "%s AND ",
                                                          completion_squery->viscondition);
                        appendPQExpBuffer(&query_buffer, "substring(%s,1,%d)='%s'",
                                                          completion_squery->result,
                                                          string_length, e_text);
                        /*
                         * When fetching relation names, suppress system catalogs unless
                         * the input-so-far begins with "pg_".  This is a compromise
                         * between not offering system catalogs for completion at all,
                         * and having them swamp the result when the input is just "p".
                         */
                        if (strcmp(completion_squery->catname,
                                           "pg_catalog.pg_class c") == 0 &&
                                strncmp(text, "pg_", 3) != 0)
                        {
                                appendPQExpBuffer(&query_buffer,
                                                                  " AND c.relnamespace <> (SELECT oid FROM"
                                                                  " pg_catalog.pg_namespace WHERE nspname = 'pg_catalog')");
                        }

                        /*
                         * Add in matching schema names, but only if there is more than
                         * one potential match among schema names.
                         */
                        appendPQExpBuffer(&query_buffer, "\nUNION\n"
                                                          "SELECT pg_catalog.quote_ident(n.nspname) || '.' "
                                                          "FROM pg_catalog.pg_namespace n "
                                                          "WHERE substring(pg_catalog.quote_ident(n.nspname) || '.',1,%d)='%s'",
                                                          string_length, e_text);
                        appendPQExpBuffer(&query_buffer,
                                                          " AND (SELECT pg_catalog.count(*)"
                                                          " FROM pg_catalog.pg_namespace"
                                                          " WHERE substring(pg_catalog.quote_ident(nspname) || '.',1,%d) ="
                                                          " substring('%s',1,pg_catalog.length(pg_catalog.quote_ident(nspname))+1)) > 1",
                                                          string_length, e_text);

                        /*
                         * Add in matching qualified names, but only if there is exactly
                         * one schema matching the input-so-far.
                         */
                        appendPQExpBuffer(&query_buffer, "\nUNION\n"
                                                          "SELECT pg_catalog.quote_ident(n.nspname) || '.' || %s "
                                                          "FROM %s, pg_catalog.pg_namespace n "
                                                          "WHERE %s = n.oid AND ",
                                                          qualresult,
                                                          completion_squery->catname,
                                                          completion_squery->namespace);
                        if (completion_squery->selcondition)
                                appendPQExpBuffer(&query_buffer, "%s AND ",
                                                                  completion_squery->selcondition);
                        appendPQExpBuffer(&query_buffer, "substring(pg_catalog.quote_ident(n.nspname) || '.' || %s,1,%d)='%s'",
                                                          qualresult,
                                                          string_length, e_text);
                        /* This condition exploits the single-matching-schema rule to speed up the query */
                        appendPQExpBuffer(&query_buffer,
                                                          " AND substring(pg_catalog.quote_ident(n.nspname) || '.',1,%d) ="
                                                          " substring('%s',1,pg_catalog.length(pg_catalog.quote_ident(n.nspname))+1)",
                                                          string_length, e_text);
                        appendPQExpBuffer(&query_buffer,
                                                          " AND (SELECT pg_catalog.count(*)"
                                                          " FROM pg_catalog.pg_namespace"
                                                          " WHERE substring(pg_catalog.quote_ident(nspname) || '.',1,%d) ="
                                                          " substring('%s',1,pg_catalog.length(pg_catalog.quote_ident(nspname))+1)) = 1",
                                                          string_length, e_text);

                        /* If an addon query was provided, use it */
                        if (completion_charp)
                                appendPQExpBuffer(&query_buffer, "\n%s", completion_charp);
                }
                else
                {
                        /* completion_charp is an sprintf-style format string */
                        appendPQExpBuffer(&query_buffer, completion_charp,
                                                          string_length, e_text, e_info_charp);
                }

                /* Limit the number of records in the result */
                appendPQExpBuffer(&query_buffer, "\nLIMIT %d",
                                                  completion_max_records);

                result = exec_query(query_buffer.data);

                termPQExpBuffer(&query_buffer);

                if (e_text)
                        free(e_text);
                if (e_info_charp)
                        free(e_info_charp);
        }

        /* Find something that matches */
        if (result && PQresultStatus(result) == PGRES_TUPLES_OK)
        {
                const char *item;

                while (list_index < PQntuples(result) &&
                           (item = PQgetvalue(result, list_index++, 0)))
                        if (pg_strncasecmp(text, item, string_length) == 0)
                                return pg_strdup(item);
        }

        /* If nothing matches, free the db structure and return null */
        PQclear(result);
        result = NULL;
        return NULL;
}


/* This function returns in order one of a fixed, NULL pointer terminated list
   of strings (if matching). This can be used if there are only a fixed number
   SQL words that can appear at certain spot.
*/
static char *
complete_from_list(const char *text, int state)
{
        static int      string_length,
                                list_index,
                                matches;
        static bool casesensitive;
        const char *item;

        /* need to have a list */
        psql_assert(completion_charpp);

        /* Initialization */
        if (state == 0)
        {
                list_index = 0;
                string_length = strlen(text);
                casesensitive = true;
                matches = 0;
        }

        while ((item = completion_charpp[list_index++]))
        {
                /* First pass is case sensitive */
                if (casesensitive && strncmp(text, item, string_length) == 0)
                {
                        matches++;
                        return pg_strdup(item);
                }

                /* Second pass is case insensitive, don't bother counting matches */
                if (!casesensitive && pg_strncasecmp(text, item, string_length) == 0)
                        return pg_strdup(item);
        }

        /*
         * No matches found. If we're not case insensitive already, lets
         * switch to being case insensitive and try again
         */
        if (casesensitive && matches == 0)
        {
                casesensitive = false;
                list_index = 0;
                state++;
                return (complete_from_list(text, state));
        }

        /* If no more matches, return null. */
        return NULL;
}


/* This function returns one fixed string the first time even if it doesn't
   match what's there, and nothing the second time. This should be used if there
   is only one possibility that can appear at a certain spot, so misspellings
   will be overwritten.
   The string to be passed must be in completion_charp.
*/
static char *
complete_from_const(const char *text, int state)
{
        (void) text;                            /* We don't care about what was entered
                                                                 * already. */

        psql_assert(completion_charp);
        if (state == 0)
                return pg_strdup(completion_charp);
        else
                return NULL;
}



/* HELPER FUNCTIONS */


/*
 * Execute a query and report any errors. This should be the preferred way of
 * talking to the database in this file.
 */
static PGresult *
exec_query(const char *query)
{
        PGresult   *result;

        if (query == NULL || !pset.db || PQstatus(pset.db) != CONNECTION_OK)
                return NULL;

        result = PQexec(pset.db, query);

        if (result != NULL && PQresultStatus(result) != PGRES_TUPLES_OK)
        {
#if 0
                psql_error("tab completion: %s failed - %s\n",
                                   query, PQresStatus(PQresultStatus(result)));
#endif
                PQclear(result);
                result = NULL;
        }

        return result;
}



/* Return the word (space delimited) before point. Set skip > 0 to skip that
   many words; e.g. skip=1 finds the word before the previous one.
*/
static char *
previous_word(int point, int skip)
{
        int                     i,
                                start = 0,
                                end = -1,
                                inquotes = 0;
        char       *s;

        while (skip-- >= 0)
        {
                /* first we look for a space before the current word */
                for (i = point; i >= 0; i--)
                        if (rl_line_buffer[i] == ' ')
                                break;

                /* now find the first non-space which then constitutes the end */
                for (; i >= 0; i--)
                        if (rl_line_buffer[i] != ' ')
                        {
                                end = i;
                                break;
                        }

                /*
                 * If no end found we return null, because there is no word before
                 * the point
                 */
                if (end == -1)
                        return NULL;

                /*
                 * Otherwise we now look for the start. The start is either the
                 * last character before any space going backwards from the end,
                 * or it's simply character 0
                 */
                for (start = end; start > 0; start--)
                {
                        if (rl_line_buffer[start] == '"')
                                inquotes = !inquotes;
                        if ((rl_line_buffer[start - 1] == ' ') && inquotes == 0)
                                break;
                }

                point = start;
        }

        /* make a copy */
        s = pg_malloc(end - start + 2);

        strncpy(s, &rl_line_buffer[start], end - start + 1);
        s[end - start + 1] = '\0';

        return s;
}



#if 0

/*
 * Surround a string with single quotes. This works for both SQL and
 * psql internal. Currently disabled because it is reported not to
 * cooperate with certain versions of readline.
 */
static char *
quote_file_name(char *text, int match_type, char *quote_pointer)
{
        char       *s;
        size_t          length;

        (void) quote_pointer;           /* not used */

        length = strlen(text) +(match_type == SINGLE_MATCH ? 3 : 2);
        s = pg_malloc(length);
        s[0] = '\'';
        strcpy(s + 1, text);
        if (match_type == SINGLE_MATCH)
                s[length - 2] = '\'';
        s[length - 1] = '\0';
        return s;
}



static char *
dequote_file_name(char *text, char quote_char)
{
        char       *s;
        size_t          length;

        if (!quote_char)
                return pg_strdup(text);

        length = strlen(text);
        s = pg_malloc(length - 2 + 1);
        strncpy(s, text +1, length - 2);
        s[length] = '\0';

        return s;
}
#endif   /* 0 */

#endif   /* USE_READLINE */