#    interface_definition.rnc: VyConf reference tree XML grammar
#
#    Copyright (C) 2014. 2017 VyOS maintainers and contributors <maintainers@vyos.net>
#
#    This library is free software; you can redistribute it and/or
#    modify it under the terms of the GNU Lesser General Public
#    License as published by the Free Software Foundation; either
#    version 2.1 of the License, or (at your option) any later version.
#
#    This library is distributed in the hope that it will be useful,
#    but WITHOUT ANY WARRANTY; without even the implied warranty of
#    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
#    Lesser General Public License for more details.
#
#    You should have received a copy of the GNU Lesser General Public
#    License along with this library; if not, write to the Free Software
#    Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301
#    USA

# The language of this file is compact form RELAX-NG
# http://relaxng.org/compact-tutorial-20030326.htm
# (unless converted to XML, then just RELAX-NG :)

# Interface definition starts with interfaceDefinition tag that may contain node tags
start = element interfaceDefinition
{
    node*
}

# node tag may contain node, leafNode, or tagNode tags
# Those are intermediate configuration nodes that may only contain
# other nodes and must not have values
node = element node
{
    (ownerAttr? & nodeNameAttr),
    (properties? & children? )
}

# Tag nodes are containers for nodes without predefined names, like network interfaces
# or user names (e.g. "interfaces ethernet eth0" or "user jrandomhacker")
# Tag nodes may contain node and leafNode elements, and also nameConstraint tags
# They must not contain other tag nodes
tagNode = element tagNode
{
    (ownerAttr? & nodeNameAttr),
    (defaultValue? & properties? & children )
}

# Leaf nodes are terminal configuration nodes that can't have children,
# but can have values.
# Leaf node may contain one or more valueConstraint tags
# If multiple valueConstraint tags are used, they work a logical OR
# Leaf nodes can have "multi" attribute that indicated that it can have more than one value
# It can also have a default value
leafNode = element leafNode
{
    (ownerAttr? & nodeNameAttr),
    (defaultValue? & properties)
}

# Default value for leaf node, if applicable
# It is used to generate default node state representation
defaultValue = element defaultValue { text }

# Normal and tag nodes may have children
children = element children
{
    (node | tagNode | leafNode)+
}

# Nodes may have properties
# For simplicity, any property is allowed in any node,
# but whether they are used or not is implementation-defined
#
# Leaf nodes may differ in number of values that can be
# associated with them.
# By default, a leaf node can have only one value.
# "multi" tag means a node can have one or more values,
# "valueless" means it can have no values at all.
# "hidden" means node visibility can be toggled, eg 'dangerous' commands,
# "secret" allows a node to hide its value from unprivileged users.
#
# "priority" is used to influence node processing order for nodes
# with exact same dependencies and in compatibility modes.
properties = element properties
{
    help? &
    constraint? &
    constraintGroup* &
    valueHelp* &
    (element constraintErrorMessage { text })? &
    completionHelp* &

    # These are meaningful only for leaf nodes
    (element valueless { empty })? &
    (element multi { empty })? &
    (element hidden { empty })? &
    (element secret { empty })? &
    (element priority { text })? &

    # These are meaningful only for tag nodes
    (element keepChildOrder { empty })?
}

# All nodes must have "name" attribute
nodeNameAttr = attribute name
{
    text
}

# Ordinary nodes and tag nodes can have "owner" attribute.
# Owner is the component that is notified when node changes.
ownerAttr = attribute owner
{
    text
}

# Tag and leaf nodes may have constraints on their names and values
# (respectively).
# When multiple constraints are listed, they work as logical OR
constraint = element constraint
{
    ( (element regex { text }) |
      validator )+
}

# Tag and leaf nodes may have constraintGroups on their names and
# values (respectively).
# When multiple constraints are listed within a group, they work as
# logical AND
constraintGroup = element constraintGroup
{
    ( (element regex { text }) |
      validator )+
}

# A constraint may also use an external validator rather than regex
validator = element validator
{
    ( (attribute name { text })  &
      (attribute argument { text })? ),
    empty
}

# help tags contains brief description of the purpose of the node
help = element help
{
    text
}

# valueHelp tags contain information about acceptable value format
valueHelp = element valueHelp
{
    element format { text } &
    element description { text }
}

# completionHelp tags contain information about allowed values of a node that is used for generating
# tab completion in the CLI frontend and drop-down lists in GUI frontends
# It is only meaninful for leaf nodes
# Allowed values can be given as a fixed list of values (e.g. <list>foo bar baz</list>),
# as a configuration path (e.g. <path>interfaces ethernet</path>),
# or as a path to a script file that generates the list (e.g. <script>/usr/lib/foo/list-things</script>
completionHelp = element completionHelp
{
    (element list { text })* &
    (element path { text })* &
    (element script { text })*
}