LIBXO(3) BSD Library Functions Manual LIBXO(3)NAME
xo_emit — emit formatted output based on format string and arguments
LIBRARY
library “libxo”
SYNOPSIS
#include <libxo/xo.h>
LIBXO(3) BSD Library Functions Manual LIBXO(3)NAMExo_open_list
xo_open_list_h
xo_open_list_hd
xo_open_list_d
xo_open_instance
xo_open_instance_h
xo_open_instance_hd
xo_open_instance_d
xo_close_instance
xo_close_instance_h
xo_close_instance_hd
xo_close_instance_d
xo_close_list
xo_close_list_h
xo_close_list_hd
xo_close_list_d — open and close lists and instances
LIBRARY
library “libxo”
SYNOPSIS
int
xo_open_list_h(xo_handle_t *xop, const char *name);
int
xo_open_list(const char *name);
int
xo_open_list_hd(xo_handle_t *xop, const char *name);
int
xo_open_list_d(const char *name);
int
xo_open_instance_h(xo_handle_t *xop, const char *name);
int
xo_open_instance(const char *name);
int
xo_open_instance_hd(xo_handle_t *xop, const char *name);
int
xo_open_instance_d(const char *name);
int
xo_close_instance_h(xo_handle_t *xop, const char *name);
int
xo_close_instance(const char *name);
int
xo_close_instance_hd(xo_handle_t *xop);
int
xo_close_instance_d(void);
int
xo_close_list_h(xo_handle_t *xop, const char *name);
int
xo_close_list(const char *name);
int
xo_close_list_hd(xo_handle_t *xop);
int
xo_close_list_d(void);
DESCRIPTION
Lists are sequences of instances of homogeneous data objects. Two dis‐
tinct levels of calls are needed to represent them in our output styles.
Calls must be made to open and close a list, and for each instance of
data in that list, calls must be make to open and close that instance.
The name given to all calls must be identical, and it is strongly sug‐
gested that the name be singular, not plural, as a matter of style and
usage expectations.
A list is a set of one or more instances that appear under the same par‐
ent. The instances contain details about a specific object. One can
think of instances as objects or records. A call is needed to open and
close the list, while a distinct call is needed to open and close each
instance of the list:
xo_open_list("item");
for (ip = list; ip->i_title; ip++) {
xo_open_instance("item");
xo_emit("{L:Item} '{:name/%s}':0, ip->i_title);
xo_close_instance("item");
}
xo_close_list("item");
Getting the list and instance calls correct is critical to the proper
generation of XML and JSON data.
EXAMPLE:
xo_open_list("user");
for (i = 0; i < num_users; i++) {
xo_open_instance("user");
xo_emit("{k:name}:{:uid/%u}:{:gid/%u}:{:home}0,
pw[i].pw_name, pw[i].pw_uid,
pw[i].pw_gid, pw[i].pw_dir);
xo_close_instance("user");
}
xo_close_list("user");
TEXT:
phil:1001:1001:/home/phil
pallavi:1002:1002:/home/pallavi
XML:
<user>
<name>phil</name>
<uid>1001</uid>
<gid>1001</gid>
<home>/home/phil</home>
</user>
<user>
<name>pallavi</name>
<uid>1002</uid>
<gid>1002</gid>
<home>/home/pallavi</home>
</user>
JSON:
user: [
{
"name": "phil",
"uid": 1001,
"gid": 1001,
"home": "/home/phil",
},
{
"name": "pallavi",
"uid": 1002,
"gid": 1002,
"home": "/home/pallavi",
}
]
LEAF LISTS
In contrast to a list of instances, a "leaf list" is list of simple val‐
ues. To emit a leaf list, call the xo_emit() function using the ""l""
modifier:
for (ip = list; ip->i_title; ip++) {
xo_emit("{Lwc:Item}{l:item}0, ip->i_title);
}
The name of the field must match the name of the leaf list.
In JSON, leaf lists are rendered as arrays of values. In XML, they are
rendered as multiple leaf elements.
JSON:
"item": "hammer", "nail"
XML:
<item>hammer</item>
<item>nail</item>
ADDITIONAL DOCUMENTATION
Complete documentation can be found on github:
http://juniper.github.io/libxo/libxo-manual.html
libxo lives on github as:
https://github.com/Juniper/libxo
The latest release of libxo is available at:
https://github.com/Juniper/libxo/releases
SEE ALSOxo_emit(3)HISTORY
The libxo library was added in FreeBSD 11.0.
AUTHOR
Phil Shafer
BSD December 4, 2014 BSD
