src/backend/replication/syncrep_gram.y

%{
/*-------------------------------------------------------------------------
 *
 * syncrep_gram.y				- Parser for synchronous_standby_names
 *
 * Portions Copyright (c) 1996-2021, PostgreSQL Global Development Group
 * Portions Copyright (c) 1994, Regents of the University of California
 *
 *
 * IDENTIFICATION
 *	  src/backend/replication/syncrep_gram.y
 *
 *-------------------------------------------------------------------------
 */
#include "postgres.h"

#include "replication/syncrep.h"

/* Result of parsing is returned in one of these two variables */
SyncRepConfigData *syncrep_parse_result;
char	   *syncrep_parse_error_msg;

static SyncRepConfigData *create_syncrep_config(const char *num_sync,
					List *members, uint8 syncrep_method);

/*
 * Bison doesn't allocate anything that needs to live across parser calls,
 * so we can easily have it use palloc instead of malloc.  This prevents
 * memory leaks if we error out during parsing.  Note this only works with
 * bison >= 2.0.  However, in bison 1.875 the default is to use alloca()
 * if possible, so there's not really much problem anyhow, at least if
 * you're building with gcc.
 */
#define YYMALLOC palloc
#define YYFREE   pfree

%}

%expect 0
%name-prefix="syncrep_yy"

%union
{
	char	   *str;
	List	   *list;
	SyncRepConfigData *config;
}

%token <str> NAME NUM JUNK ANY FIRST

%type <config> result standby_config
%type <list> standby_list
%type <str> standby_name

%start result

%%
result:
		standby_config				{ syncrep_parse_result = $1; }
	;

standby_config:
		standby_list				{ $$ = create_syncrep_config("1", $1, SYNC_REP_PRIORITY); }
		| NUM '(' standby_list ')'		{ $$ = create_syncrep_config($1, $3, SYNC_REP_PRIORITY); }
		| ANY NUM '(' standby_list ')'		{ $$ = create_syncrep_config($2, $4, SYNC_REP_QUORUM); }
		| FIRST NUM '(' standby_list ')'		{ $$ = create_syncrep_config($2, $4, SYNC_REP_PRIORITY); }
	;

standby_list:
		standby_name						{ $$ = list_make1($1); }
		| standby_list ',' standby_name		{ $$ = lappend($1, $3); }
	;

standby_name:
		NAME						{ $$ = $1; }
		| NUM						{ $$ = $1; }
	;
%%

static SyncRepConfigData *
create_syncrep_config(const char *num_sync, List *members, uint8 syncrep_method)
{
	SyncRepConfigData *config;
	int			size;
	ListCell   *lc;
	char	   *ptr;

	/* Compute space needed for flat representation */
	size = offsetof(SyncRepConfigData, member_names);
	foreach(lc, members)
	{
		char	   *standby_name = (char *) lfirst(lc);

		size += strlen(standby_name) + 1;
	}

	/* And transform the data into flat representation */
	config = (SyncRepConfigData *) palloc(size);

	config->config_size = size;
	config->num_sync = atoi(num_sync);
	config->syncrep_method = syncrep_method;
	config->nmembers = list_length(members);
	ptr = config->member_names;
	foreach(lc, members)
	{
		char	   *standby_name = (char *) lfirst(lc);

		strcpy(ptr, standby_name);
		ptr += strlen(standby_name) + 1;
	}

	return config;
}

#include "syncrep_scanner.c"