gram.y

postgresql8.3.4源码,开源数据库

		if ((tok == ',' || tok == ')') && parenlevel == 0)
			break;
		if (tok == '(')
			parenlevel++;
		else if (tok == ')')
			parenlevel--;
		if (needspace)
			plpgsql_dstring_append(&ds, " ");
		needspace = true;
		plpgsql_dstring_append(&ds, yytext);

		tok = yylex();
	}

	plpgsql_push_back_token(tok);

	type_name = plpgsql_dstring_get(&ds);

	if (type_name[0] == '\0')
		yyerror("missing datatype declaration");

	plpgsql_error_lineno = lno;	/* in case of error in parse_datatype */

	result = plpgsql_parse_datatype(type_name);

	plpgsql_dstring_free(&ds);

	return result;
}

static PLpgSQL_stmt *
make_execsql_stmt(const char *sqlstart, int lineno)
{
	PLpgSQL_dstring		ds;
	int					nparams = 0;
	int					params[MAX_EXPR_PARAMS];
	char				buf[32];
	PLpgSQL_stmt_execsql *execsql;
	PLpgSQL_expr		*expr;
	PLpgSQL_row			*row = NULL;
	PLpgSQL_rec			*rec = NULL;
	int					tok;
	bool				have_into = false;
	bool				have_strict = false;

	plpgsql_dstring_init(&ds);
	plpgsql_dstring_append(&ds, sqlstart);

	for (;;)
	{
		tok = yylex();
		if (tok == ';')
			break;
		if (tok == 0)
			yyerror("unexpected end of function definition");
		if (tok == K_INTO)
		{
			if (have_into)
				yyerror("INTO specified more than once");
			have_into = true;
			read_into_target(&rec, &row, &have_strict);
			continue;
		}

		if (plpgsql_SpaceScanned)
			plpgsql_dstring_append(&ds, " ");

		switch (tok)
		{
			case T_SCALAR:
				snprintf(buf, sizeof(buf), " $%d ",
						 assign_expr_param(yylval.scalar->dno,
										   params, &nparams));
				plpgsql_dstring_append(&ds, buf);
				break;

			case T_ROW:
				snprintf(buf, sizeof(buf), " $%d ",
						 assign_expr_param(yylval.row->rowno,
										   params, &nparams));
				plpgsql_dstring_append(&ds, buf);
				break;

			case T_RECORD:
				snprintf(buf, sizeof(buf), " $%d ",
						 assign_expr_param(yylval.rec->recno,
										   params, &nparams));
				plpgsql_dstring_append(&ds, buf);
				break;

			default:
				plpgsql_dstring_append(&ds, yytext);
				break;
		}
	}

	expr = palloc(sizeof(PLpgSQL_expr) + sizeof(int) * nparams - sizeof(int));
	expr->dtype			= PLPGSQL_DTYPE_EXPR;
	expr->query			= pstrdup(plpgsql_dstring_get(&ds));
	expr->plan			= NULL;
	expr->nparams		= nparams;
	while(nparams-- > 0)
		expr->params[nparams] = params[nparams];
	plpgsql_dstring_free(&ds);

	check_sql_expr(expr->query);

	execsql = palloc(sizeof(PLpgSQL_stmt_execsql));
	execsql->cmd_type = PLPGSQL_STMT_EXECSQL;
	execsql->lineno  = lineno;
	execsql->sqlstmt = expr;
	execsql->into	 = have_into;
	execsql->strict	 = have_strict;
	execsql->rec	 = rec;
	execsql->row	 = row;

	return (PLpgSQL_stmt *) execsql;
}


static PLpgSQL_stmt_fetch *
read_fetch_direction(void)
{
	PLpgSQL_stmt_fetch *fetch;
	int			tok;
	bool		check_FROM = true;

	/*
	 * We create the PLpgSQL_stmt_fetch struct here, but only fill in
	 * the fields arising from the optional direction clause
	 */
	fetch = (PLpgSQL_stmt_fetch *) palloc0(sizeof(PLpgSQL_stmt_fetch));
	fetch->cmd_type = PLPGSQL_STMT_FETCH;
	/* set direction defaults: */
	fetch->direction = FETCH_FORWARD;
	fetch->how_many  = 1;
	fetch->expr      = NULL;

	/*
	 * Most of the direction keywords are not plpgsql keywords, so we
	 * rely on examining yytext ...
	 */
	tok = yylex();
	if (tok == 0)
		yyerror("unexpected end of function definition");

	if (pg_strcasecmp(yytext, "next") == 0)
	{
		/* use defaults */
	}
	else if (pg_strcasecmp(yytext, "prior") == 0)
	{
		fetch->direction = FETCH_BACKWARD;
	}
	else if (pg_strcasecmp(yytext, "first") == 0)
	{
		fetch->direction = FETCH_ABSOLUTE;
	}
	else if (pg_strcasecmp(yytext, "last") == 0)
	{
		fetch->direction = FETCH_ABSOLUTE;
		fetch->how_many  = -1;
	}
	else if (pg_strcasecmp(yytext, "absolute") == 0)
	{
		fetch->direction = FETCH_ABSOLUTE;
		fetch->expr = read_sql_construct(K_FROM, K_IN, "FROM or IN",
										 "SELECT ", true, true, NULL);
		check_FROM = false;
	}
	else if (pg_strcasecmp(yytext, "relative") == 0)
	{
		fetch->direction = FETCH_RELATIVE;
		fetch->expr = read_sql_construct(K_FROM, K_IN, "FROM or IN",
										 "SELECT ", true, true, NULL);
		check_FROM = false;
	}
	else if (pg_strcasecmp(yytext, "forward") == 0)
	{
		/* use defaults */
	}
	else if (pg_strcasecmp(yytext, "backward") == 0)
	{
		fetch->direction = FETCH_BACKWARD;
	}
	else if (tok != T_SCALAR)
	{
		plpgsql_push_back_token(tok);
		fetch->expr = read_sql_construct(K_FROM, K_IN, "FROM or IN",
										 "SELECT ", true, true, NULL);
		check_FROM = false;
	}
	else
	{
		/* Assume there's no direction clause */
		plpgsql_push_back_token(tok);
		check_FROM = false;
	}

	/* check FROM or IN keyword after direction's specification */
	if (check_FROM)
	{
		tok = yylex();
		if (tok != K_FROM && tok != K_IN)
			yyerror("expected FROM or IN");
	}

	return fetch;
}


static PLpgSQL_stmt *
make_return_stmt(int lineno)
{
	PLpgSQL_stmt_return *new;

	new = palloc0(sizeof(PLpgSQL_stmt_return));
	new->cmd_type = PLPGSQL_STMT_RETURN;
	new->lineno   = lineno;
	new->expr	  = NULL;
	new->retvarno = -1;

	if (plpgsql_curr_compile->fn_retset)
	{
		if (yylex() != ';')
			yyerror("RETURN cannot have a parameter in function "
					"returning set; use RETURN NEXT or RETURN QUERY");
	}
	else if (plpgsql_curr_compile->out_param_varno >= 0)
	{
		if (yylex() != ';')
			yyerror("RETURN cannot have a parameter in function with OUT parameters");
		new->retvarno = plpgsql_curr_compile->out_param_varno;
	}
	else if (plpgsql_curr_compile->fn_rettype == VOIDOID)
	{
		if (yylex() != ';')
			yyerror("RETURN cannot have a parameter in function returning void");
	}
	else if (plpgsql_curr_compile->fn_retistuple)
	{
		switch (yylex())
		{
			case K_NULL:
				/* we allow this to support RETURN NULL in triggers */
				break;

			case T_ROW:
				new->retvarno = yylval.row->rowno;
				break;

			case T_RECORD:
				new->retvarno = yylval.rec->recno;
				break;

			default:
				yyerror("RETURN must specify a record or row variable in function returning tuple");
				break;
		}
		if (yylex() != ';')
			yyerror("RETURN must specify a record or row variable in function returning tuple");
	}
	else
	{
		/*
		 * Note that a well-formed expression is
		 * _required_ here; anything else is a
		 * compile-time error.
		 */
		new->expr = plpgsql_read_expression(';', ";");
	}

	return (PLpgSQL_stmt *) new;
}


static PLpgSQL_stmt *
make_return_next_stmt(int lineno)
{
	PLpgSQL_stmt_return_next *new;

	if (!plpgsql_curr_compile->fn_retset)
		yyerror("cannot use RETURN NEXT in a non-SETOF function");

	new = palloc0(sizeof(PLpgSQL_stmt_return_next));
	new->cmd_type	= PLPGSQL_STMT_RETURN_NEXT;
	new->lineno		= lineno;
	new->expr		= NULL;
	new->retvarno	= -1;

	if (plpgsql_curr_compile->out_param_varno >= 0)
	{
		if (yylex() != ';')
			yyerror("RETURN NEXT cannot have a parameter in function with OUT parameters");
		new->retvarno = plpgsql_curr_compile->out_param_varno;
	}
	else if (plpgsql_curr_compile->fn_retistuple)
	{
		switch (yylex())
		{
			case T_ROW:
				new->retvarno = yylval.row->rowno;
				break;

			case T_RECORD:
				new->retvarno = yylval.rec->recno;
				break;

			default:
				yyerror("RETURN NEXT must specify a record or row variable in function returning tuple");
				break;
		}
		if (yylex() != ';')
			yyerror("RETURN NEXT must specify a record or row variable in function returning tuple");
	}
	else
		new->expr = plpgsql_read_expression(';', ";");

	return (PLpgSQL_stmt *) new;
}


static PLpgSQL_stmt *
make_return_query_stmt(int lineno)
{
	PLpgSQL_stmt_return_query *new;

	if (!plpgsql_curr_compile->fn_retset)
		yyerror("cannot use RETURN QUERY in a non-SETOF function");

	new = palloc0(sizeof(PLpgSQL_stmt_return_query));
	new->cmd_type = PLPGSQL_STMT_RETURN_QUERY;
	new->lineno = lineno;
	new->query = read_sql_construct(';', 0, ")", "", false, true, NULL);

	return (PLpgSQL_stmt *) new;
}


static void
check_assignable(PLpgSQL_datum *datum)
{
	switch (datum->dtype)
	{
		case PLPGSQL_DTYPE_VAR:
			if (((PLpgSQL_var *) datum)->isconst)
			{
				plpgsql_error_lineno = plpgsql_scanner_lineno();
				ereport(ERROR,
						(errcode(ERRCODE_ERROR_IN_ASSIGNMENT),
						 errmsg("\"%s\" is declared CONSTANT",
								((PLpgSQL_var *) datum)->refname)));
			}
			break;
		case PLPGSQL_DTYPE_ROW:
			/* always assignable? */
			break;
		case PLPGSQL_DTYPE_REC:
			/* always assignable?  What about NEW/OLD? */
			break;
		case PLPGSQL_DTYPE_RECFIELD:
			/* always assignable? */
			break;
		case PLPGSQL_DTYPE_ARRAYELEM:
			/* always assignable? */
			break;
		case PLPGSQL_DTYPE_TRIGARG:
			yyerror("cannot assign to tg_argv");
			break;
		default:
			elog(ERROR, "unrecognized dtype: %d", datum->dtype);
			break;
	}
}

/*
 * Read the argument of an INTO clause.  On entry, we have just read the
 * INTO keyword.
 */
static void
read_into_target(PLpgSQL_rec **rec, PLpgSQL_row **row, bool *strict)
{
	int			tok;

	/* Set default results */
	*rec = NULL;
	*row = NULL;
	if (strict)
		*strict = false;

	tok = yylex();
	if (strict && tok == K_STRICT)
	{
		*strict = true;
		tok = yylex();
	}

	switch (tok)
	{
		case T_ROW:
			*row = yylval.row;
			check_assignable((PLpgSQL_datum *) *row);
			break;

		case T_RECORD:
			*rec = yylval.rec;
			check_assignable((PLpgSQL_datum *) *rec);
			break;

		case T_SCALAR:
			*row = read_into_scalar_list(yytext, yylval.scalar);
			break;

		default:
			plpgsql_error_lineno = plpgsql_scanner_lineno();
			ereport(ERROR,
					(errcode(ERRCODE_SYNTAX_ERROR),
					 errmsg("syntax error at \"%s\"", yytext),
					 errdetail("Expected record variable, row variable, "
							   "or list of scalar variables following INTO.")));
	}
}

/*
 * Given the first datum and name in the INTO list, continue to read
 * comma-separated scalar variables until we run out. Then construct
 * and return a fake "row" variable that represents the list of
 * scalars.
 */
static PLpgSQL_row *
read_into_scalar_list(const char *initial_name,
					  PLpgSQL_datum *initial_datum)
{
	int				 nfields;
	char			*fieldnames[1024];
	int				 varnos[1024];
	PLpgSQL_row		*row;
	int				 tok;

	check_assignable(initial_datum);
	fieldnames[0] = pstrdup(initial_name);
	varnos[0]	  = initial_datum->dno;
	nfields		  = 1;

	while ((tok = yylex()) == ',')
	{
		/* Check for array overflow */
		if (nfields >= 1024)
		{
			plpgsql_error_lineno = plpgsql_scanner_lineno();
			ereport(ERROR,
					(errcode(ERRCODE_PROGRAM_LIMIT_EXCEEDED),
					 errmsg("too many INTO variables specified")));
		}

		tok = yylex();
		switch(tok)
		{
			case T_SCALAR:
				check_assignable(yylval.scalar);
				fieldnames[nfields] = pstrdup(yytext);
				varnos[nfields++]	= yylval.scalar->dno;
				break;

			default:
				plpgsql_error_lineno = plpgsql_scanner_lineno();
				ereport(ERROR,
						(errcode(ERRCODE_SYNTAX_ERROR),
						 errmsg("\"%s\" is not a scalar variable",
								yytext)));
		}
	}

	/*
	 * We read an extra, non-comma token from yylex(), so push it
	 * back onto the input stream
	 */
	plpgsql_push_back_token(tok);

	row = palloc(sizeof(PLpgSQL_row));
	row->dtype = PLPGSQL_DTYPE_ROW;
	row->refname = pstrdup("*internal*");
	row->lineno = plpgsql_scanner_lineno();
	row->rowtupdesc = NULL;
	row->nfields = nfields;
	row->fieldnames = palloc(sizeof(char *) * nfields);
	row->varnos = palloc(sizeof(int) * nfields);
	while (--nfields >= 0)
	{
		row->fieldnames[nfields] = fieldnames[nfields];
		row->varnos[nfields] = varnos[nfields];
	}

	plpgsql_adddatum((PLpgSQL_datum *)row);

	return row;
}

/*
 * Convert a single scalar into a "row" list.  This is exactly
 * like read_into_scalar_list except we never consume any input.
 * In fact, since this can be invoked long after the source
 * input was actually read, the lineno has to be passed in.
 */
static PLpgSQL_row *
make_scalar_list1(const char *initial_name,
				  PLpgSQL_datum *initial_datum,
				  int lineno)
{
	PLpgSQL_row		*row;

	check_assignable(initial_datum);

	row = palloc(sizeof(PLpgSQL_row));
	row->dtype = PLPGSQL_DTYPE_ROW;
	row->refname = pstrdup("*internal*");
	row->lineno = lineno;
	row->rowtupdesc = NULL;
	row->nfields = 1;
	row->fieldnames = palloc(sizeof(char *));
	row->varnos = palloc(sizeof(int));
	row->fieldnames[0] = pstrdup(initial_name);
	row->varnos[0] = initial_datum->dno;

	plpgsql_adddatum((PLpgSQL_datum *)row);

	return row;
}

/*
 * When the PL/PgSQL parser expects to see a SQL statement, it is very
 * liberal in what it accepts; for example, we often assume an
 * unrecognized keyword is the beginning of a SQL statement. This
 * avoids the need to duplicate parts of the SQL grammar in the
 * PL/PgSQL grammar, but it means we can accept wildly malformed
 * input. To try and catch some of the more obviously invalid input,
 * we run the strings we expect to be SQL statements through the main
 * SQL parser.
 *
 * We only invoke the raw parser (not the analyzer); this doesn't do
 * any database access and does not check any semantic rules, it just
 * checks for basic syntactic correctness. We do this here, rather
 * than after parsing has finished, because a malformed SQL statement
 * may cause the PL/PgSQL parser to become confused about statement
 * borders. So it is best to bail out as early as we can.
 */
static void
check_sql_expr(const char *stmt)
{
	ErrorContextCallback  syntax_errcontext;
	ErrorContextCallback *previous_errcontext;
	MemoryContext oldCxt;

	if (!plpgsql_check_syntax)
		return;

	/*
	 * Setup error traceback support for ereport(). The previous
	 * ereport callback is installed by pl_comp.c, but we don't want
	 * that to be invoked (since it will try to transpose the syntax
	 * error to be relative to the CREATE FUNCTION), so temporarily
	 * remove it from the list of callbacks.
	 */
	Assert(error_context_stack->callback == plpgsql_compile_error_callback);

	previous_errcontext = error_context_stack;
	syntax_errcontext.callback = plpgsql_sql_error_callback;
	syntax_errcontext.arg = (char *) stmt;
	syntax_errcontext.previous = error_context_stack->previous;
	error_context_stack = &syntax_errcontext;

	oldCxt = MemoryContextSwitchTo(compile_tmp_cxt);
	(void) raw_parser(stmt);
	MemoryContextSwitchTo(oldCxt);

	/* Restore former ereport callback */
	error_context_stack = previous_errcontext;
}

static void
plpgsql_sql_error_callback(void *arg)
{
	char *sql_stmt = (char *) arg;

	Assert(plpgsql_error_funcname);

	errcontext("SQL statement in PL/PgSQL function \"%s\" near line %d",
			   plpgsql_error_funcname, plpgsql_error_lineno);
	internalerrquery(sql_stmt);
	internalerrposition(geterrposition());
	errposition(0);
}

static char *
check_label(const char *yytxt)
{
	char	   *label_name;

	plpgsql_convert_ident(yytxt, &label_name, 1);
	if (plpgsql_ns_lookup_label(label_name) == NULL)
		yyerror("no such label");
	return label_name;
}

static void
check_labels(const char *start_label, const char *end_label)
{
	if (end_label)
	{
		if (!start_label)
		{
			plpgsql_error_lineno = plpgsql_scanner_lineno();
			ereport(ERROR,
					(errcode(ERRCODE_SYNTAX_ERROR),
					 errmsg("end label \"%s\" specified for unlabelled block",
							end_label)));
		}

		if (strcmp(start_label, end_label) != 0)
		{
			plpgsql_error_lineno = plpgsql_scanner_lineno();
			ereport(ERROR,
					(errcode(ERRCODE_SYNTAX_ERROR),
					 errmsg("end label \"%s\" differs from block's label \"%s\"",
							end_label, start_label)));
		}
	}
}

/* Needed to avoid conflict between different prefix settings: */
#undef yylex

#include "pl_scan.c"