yang.leg

%{
#include "main.h"
%}

# Start
yang=           (module-stmt !.) | (submodule-stmt !.)

module-stmt   =   optsep
                  module-keyword
                  sep
                  identifier-arg-str   @{ modname_chk(yytext); } ~{ YPERROR("<module-name>"); }
                  optsep
                  '{'
                      stmtsep
                      module-header-stmts ~{ YPERROR("module-headers (namespace & prefix)"); }
                      (
                         linkage-stmts
                       | meta-stmts
                       | revision-stmt stmtsep
                      )*
                      body-stmts
                  '}'
                  optsep

submodule-stmt  = optsep
                  submodule-keyword
                  sep
                  identifier-arg-str    ~{ YPERROR("<submodule-name>"); }
                  optsep
                  '{'
                      stmtsep
                      submodule-header-stmts ~{ YPERROR("submodule-headers (belongs-to)"); }
                      (
                         linkage-stmts
                       | meta-stmts
                       | revision-stmt stmtsep
                      )*
                      body-stmts
                  '}'
                  optsep

module-header-stmts = (yang-version-stmt stmtsep)?
                       namespace-stmt stmtsep
                       prefix-stmt stmtsep

submodule-header-stmts = (yang-version-stmt stmtsep)?
                         belongs-to-stmt stmtsep     ~{ YPERROR("belongs-to"); }

meta-stmts          =    organization-stmt stmtsep @{ meta_seen("organization");ensure_single(1, "organization"); }
                       | description-stmt stmtsep  @{ meta_seen("description");ensure_single(2, "description"); }
                       | contact-stmt stmtsep      @{ meta_seen("contact");ensure_single(3, "contact"); }
                       | reference-stmt stmtsep    @{ meta_seen("reference");ensure_single(4, "reference"); }

linkage-stmts       =   import-stmt stmtsep  @{ linkage_seen("import"); }
                      | include-stmt stmtsep @{ linkage_seen("include"); }

body-stmts          = ( ( extension-stmt
                        | feature-stmt
                        | identity-stmt
                        | typedef-stmt
                        | grouping-stmt
                        | data-def-stmt
                        | augment-stmt
                        | rpc-stmt
                        | notification-stmt
                        | deviation-stmt) stmtsep)*

data-def-stmt       =   container-stmt
                      | leaf-stmt
                      | leaf-list-stmt
                      | list-stmt
                      | choice-stmt
                      | anyxml-stmt
                      | uses-stmt

yang-version-stmt   = yang-version-keyword
                      sep
                      yang-version-arg-str ~{ YPERROR("yang-version"); }
                      optsep
                      stmtend

yang-version-arg-str =   DQUOTE yang-version-arg DQUOTE
                       | SQUOTE yang-version-arg SQUOTE
                       | yang-version-arg

yang-version-arg    = '1'

import-stmt         = import-keyword
                      sep
                      identifier-arg-str
                      optsep
                      '{'
                          stmtsep
                          prefix-stmt  ~{ YPERROR("prefix"); }
                          stmtsep
                          (revision-date-stmt stmtsep)?
                      '}'

include-stmt        = include-keyword
                      sep
                      identifier-arg-str
                      optsep
                      ( ';'
                       | '{'
                           stmtsep
                           (revision-date-stmt stmtsep)?
                         '}'
                       )

namespace-stmt      = namespace-keyword
                      sep
                      uri-str  ~{ YPERROR("uri-str"); }
                      optsep
                      stmtend


uri-str             = string  # TODO # < a string that matches the rule URI in RFC 3986 >

prefix-stmt         = prefix-keyword
                      sep
                      prefix-arg-str  ~{ YPERROR("prefix-name"); }
                      optsep
                      stmtend

belongs-to-stmt     = belongs-to-keyword
                      sep
                      identifier-arg-str   ~{ YPERROR("<parent-module-name>"); }
                      optsep
                      '{'
                          stmtsep
                          prefix-stmt stmtsep  ~{ YPERROR("prefix"); }
                      '}'

organization-stmt   = organization-keyword
                      sep
                      string
                      optsep
                      stmtend

contact-stmt        = contact-keyword
                      sep
                      string
                      optsep
                      stmtend

description-stmt    = description-keyword
                      sep
                      jstring+ ~{ YPERROR("string"); }
                      optsep
                      stmtend

reference-stmt      = reference-keyword
                      sep
                      string
                      optsep
                      stmtend

units-stmt          = units-keyword
                      sep
                      string
                      optsep
                      stmtend

revision-stmt       = revision-keyword  @{ revision_seen(); }
                      sep
                      revision-date      { revision_date_chk(yytext); }
                      optsep
                      (  ';'
                       | '{'
                            stmtsep
                            (description-stmt stmtsep)?
                            (reference-stmt stmtsep)?
                         '}'
                      )

revision-date       =  date-arg-str

revision-date-stmt  = revision-date-keyword
                      sep
                      revision-date
                      stmtend

extension-stmt      =  extension-keyword
                       sep
                       identifier-arg-str
                       optsep
                       (  ';'
                        | '{'
                            stmtsep
                            # these stmts can appear in any order
                            (argument-stmt stmtsep)?
                            (status-stmt stmtsep)?
                            (description-stmt stmtsep)?
                            (reference-stmt stmtsep)?
                          '}'
                       )

argument-stmt       = argument-keyword
                      sep
                      identifier-arg-str
                      optsep
                      (  ';'
                       | '{'
                           stmtsep
                           (yin-element-stmt stmtsep)?
                         '}'
                      )

yin-element-stmt    = yin-element-keyword
                      sep
                      yin-element-arg-str
                      stmtend

yin-element-arg-str =   DQUOTE yin-element-arg DQUOTE
                      | SQUOTE yin-element-arg SQUOTE
                      | yin-element-arg

yin-element-arg     = true-keyword | false-keyword

identity-stmt       =  identity-keyword
                       sep
                       identifier-arg-str
                       optsep
                       (  ';'
                        | '{'
                             stmtsep
                             # these stmts can appear in any order
                             (base-stmt stmtsep)?
                             (status-stmt stmtsep)?
                             (description-stmt stmtsep)?
                             (reference-stmt stmtsep)?
                          '}'
                       )

base-stmt           = base-keyword
                      sep
                      identifier-ref-arg-str
                      optsep
                      stmtend

feature-stmt        = feature-keyword
                      sep
                      identifier-arg-str
                      optsep
                      (  ';'
                       | '{'
                             stmtsep
                             # these stmts can appear in any order
                             (if-feature-stmt stmtsep)*
                             (status-stmt stmtsep)?
                             (description-stmt stmtsep)?
                             (reference-stmt stmtsep)?
                         '}'
                      )


if-feature-stmt     = if-feature-keyword
                      sep
                      identifier-ref-arg-str
                      optsep
                      stmtend

typedef-stmt        =  typedef-keyword
                       sep
                       identifier-arg-str
                       optsep
                       '{'
                           stmtsep
                           # these stmts can appear in any order
                           type-stmt stmtsep
                           (units-stmt stmtsep)?
                           (default-stmt stmtsep)?
                           (status-stmt stmtsep)?
                           (description-stmt stmtsep)?
                           (reference-stmt stmtsep)?
                       '}'

type-stmt           = type-keyword
                      sep
                      identifier-ref-arg-str
                      optsep
                      (  ';'
                       | '{'
                             stmtsep
                             type-body-stmts
                         '}'
                      )

type-body-stmts     =  numerical-restrictions
                     | decimal64-specification
                     | string-restrictions
                     | enum-specification
                     | leafref-specification
                     | identityref-specification
                     | instance-identifier-specification
                     | bits-specification
                     | union-specification

numerical-restrictions = range-stmt
                         stmtsep

range-stmt          =  range-keyword
                       sep
                       range-arg-str
                       optsep
                       (  ';'
                        | '{'
                             stmtsep
                             # these stmts can appear in any order
                             (error-message-stmt stmtsep)?
                             (error-app-tag-stmt stmtsep)?
                             (description-stmt stmtsep)?
                             (reference-stmt stmtsep)?
                          '}'
                        )

decimal64-specification = fraction-digits-stmt

fraction-digits-stmt = fraction-digits-keyword
                       sep
                       fraction-digits-arg-str
                       stmtend

fraction-digits-arg-str =  DQUOTE fraction-digits-arg DQUOTE
                         | SQUOTE fraction-digits-arg SQUOTE
                         | fraction-digits-arg

fraction-digits-arg = ( '1' ( '0' | '1' | '2' | '3' | '4' | '5' | '6' | '7' | '8')? )
                      | '2' | '3' | '4' | '5' | '6' | '7' | '8' | '9'

string-restrictions =  # these stmts can appear in any order
                        (length-stmt stmtsep)?
                        (pattern-stmt stmtsep)*

length-stmt         =  length-keyword
                       sep
                       length-arg-str
                       optsep
                       (  ';'
                        | '{'
                             stmtsep
                             # these stmts can appear in any order
                             (error-message-stmt stmtsep)?
                             (error-app-tag-stmt stmtsep)?
                             (description-stmt stmtsep)?
                             (reference-stmt stmtsep)?
                          '}'
                       )

pattern-stmt        = pattern-keyword
                      sep
                      string
                      optsep
                      (  ';'
                       | '{'
                             stmtsep
                             # these stmts can appear in any order
                             (error-message-stmt stmtsep)?
                             (error-app-tag-stmt stmtsep)?
                             (description-stmt stmtsep)?
                             (reference-stmt stmtsep)?
                         '}'
                      )

default-stmt        = default-keyword
                      sep
                      string
                      stmtend

enum-specification  = (enum-stmt stmtsep)* # TODO: can be only 1 repitition

enum-stmt           =  enum-keyword
                       sep
                       string
                       optsep
                       (  ';'
                        | '{'
                             stmtsep
                             # these stmts can appear in any order
                             (value-stmt stmtsep)?
                             (status-stmt stmtsep)?
                             (description-stmt stmtsep)?
                             (reference-stmt stmtsep)?
                          '}'
                       )

leafref-specification = # these stmts can appear in any order
                        path-stmt stmtsep
                        (require-instance-stmt stmtsep)?

path-stmt           = path-keyword
                      sep
                      path-arg-str
                      stmtend

require-instance-stmt = require-instance-keyword
                        sep
                        require-instance-arg-str
                        stmtend

require-instance-arg-str =  DQUOTE require-instance-arg DQUOTE
                          | SQUOTE require-instance-arg SQUOTE
                          | require-instance-arg

require-instance-arg = true-keyword | false-keyword

instance-identifier-specification = (require-instance-stmt stmtsep)?

identityref-specification = base-stmt
                            stmtsep

union-specification = (type-stmt stmtsep)* # TODO: only 1 rep

bits-specification  = (bit-stmt stmtsep)*  # TODO: only 1 rep

bit-stmt            =  bit-keyword
                       sep
                       identifier-arg-str
                       optsep
                       (  ';'
                        | '{'
                             stmtsep
                             # these stmts can appear in any order
                             (position-stmt stmtsep)?
                             (status-stmt stmtsep)?
                             (description-stmt stmtsep)?
                             (reference-stmt stmtsep)?
                          '}'
                       )

position-stmt       =  position-keyword
                       sep
                       position-value-arg-str
                       stmtend

position-value-arg-str =   DQUOTE position-value-arg DQUOTE
                         | SQUOTE position-value-arg SQUOTE
                         | position-value-arg

position-value-arg  = non-negative-integer-value

status-stmt         =  status-keyword
                       sep
                       status-arg-str
                       stmtend

status-arg-str      =   DQUOTE status-arg DQUOTE
                      | SQUOTE status-arg SQUOTE

status-arg          =   current-keyword
                      | obsolete-keyword
                      | deprecated-keyword

config-stmt         = config-keyword
                      sep
                      config-arg-str
                      stmtend

config-arg-str      =   DQUOTE config-arg DQUOTE
                      | SQUOTE config-arg SQUOTE
                      | config-arg

config-arg          =   true-keyword
                      | false-keyword

mandatory-stmt      =  mandatory-keyword
                       sep
                       mandatory-arg-str
                       stmtend

mandatory-arg-str   =   DQUOTE mandatory-arg DQUOTE
                      | SQUOTE mandatory-arg SQUOTE
                      | mandatory-arg

mandatory-arg       =    true-keyword
                       | false-keyword

presence-stmt       =  presence-keyword
                       sep
                       string
                       stmtend

ordered-by-stmt     =  ordered-by-keyword
                       sep
                       ordered-by-arg-str
                       stmtend

ordered-by-arg-str  =   DQUOTE ordered-by-arg DQUOTE
                      | SQUOTE ordered-by-arg SQUOTE
                      | ordered-by-arg

ordered-by-arg      =    user-keyword
                       | system-keyword

must-stmt           =  must-keyword
                       sep
                       string
                       optsep
                       (  ';'
                        | '{'
                             stmtsep
                             # these stmts can appear in any order
                             (error-message-stmt stmtsep)?
                             (error-app-tag-stmt stmtsep)?
                             (description-stmt stmtsep)?
                             (reference-stmt stmtsep)?
                          '}'
                       )

error-message-stmt  = error-message-keyword
                      sep
                      string
                      stmtend

error-app-tag-stmt  = error-app-tag-keyword
                      sep
                      string
                      stmtend

min-elements-stmt   = min-elements-keyword
                      sep
                      min-value-arg-str
                      stmtend

min-value-arg-str   =   DQUOTE min-value-arg DQUOTE
                      | SQUOTE min-value-arg SQUOTE
                      | min-value-arg

min-value-arg       = non-negative-integer-value

max-elements-stmt   = max-elements-keyword
                      sep
                      max-value-arg-str
                      stmtend

max-value-arg-str   =   DQUOTE max-value-arg DQUOTE
                      | SQUOTE max-value-arg SQUOTE
                      | max-value-arg

max-value-arg       =   unbounded-keyword
                      | positive-integer-value

value-stmt          =  value-keyword
                       sep
                       integer-value
                       stmtend

grouping-stmt       =  grouping-keyword
                       sep
                       identifier-arg-str
                       optsep
                       (  ';'
                        | '{'
                             stmtsep
                             # these stmts can appear in any order
                             (status-stmt stmtsep)?
                             (description-stmt stmtsep)?
                             (reference-stmt stmtsep)?
                             ((typedef-stmt |
                                grouping-stmt) stmtsep)*
                             (data-def-stmt stmtsep)*
                          '}'
                       )

container-stmt      =  container-keyword
                       sep
                       identifier-arg-str
                       optsep
                       (  ';'
                        | '{'
                             stmtsep
                             # these stmts can appear in any order
                             (when-stmt stmtsep)?
                             (if-feature-stmt stmtsep)*
                             (must-stmt stmtsep)*
                             (presence-stmt stmtsep)?
                             (config-stmt stmtsep)?
                             (status-stmt stmtsep)?
                             (description-stmt stmtsep)?
                             (reference-stmt stmtsep)?
                             ((typedef-stmt | grouping-stmt) stmtsep)*
                             (data-def-stmt stmtsep)*
                          '}'
                       )

leaf-stmt           =  leaf-keyword
                       sep
                       identifier-arg-str
                       optsep
                       '{'
                            stmtsep
                            # these stmts can appear in any order
                            (when-stmt stmtsep)?
                            (if-feature-stmt stmtsep)*
                            type-stmt stmtsep
                            (units-stmt stmtsep)?
                            (must-stmt stmtsep)*
                            (default-stmt stmtsep)?
                            (config-stmt stmtsep)?
                            (mandatory-stmt stmtsep)?
                            (status-stmt stmtsep)?
                            (description-stmt stmtsep)?
                            (reference-stmt stmtsep)?
                       '}'

leaf-list-stmt      =   leaf-list-keyword
                        sep
                        identifier-arg-str
                        optsep
                        '{'
                            stmtsep
                            # these stmts can appear in any order
                            (when-stmt stmtsep)?
                            (if-feature-stmt stmtsep)*
                            type-stmt stmtsep
                            (units-stmt stmtsep)?
                            (must-stmt stmtsep)*
                            (config-stmt stmtsep)?
                            (min-elements-stmt stmtsep)?
                            (max-elements-stmt stmtsep)?
                            (ordered-by-stmt stmtsep)?
                            (status-stmt stmtsep)?
                            (description-stmt stmtsep)?
                            (reference-stmt stmtsep)?
                         '}'

list-stmt           =   list-keyword
                        sep
                        identifier-arg-str
                        optsep
                        '{'
                            stmtsep
                            # these stmts can appear in any order
                            (when-stmt stmtsep)?
                            (if-feature-stmt stmtsep)*
                            (must-stmt stmtsep)*
                            (key-stmt stmtsep)?
                            (unique-stmt stmtsep)*
                            (config-stmt stmtsep)?
                            (min-elements-stmt stmtsep)?
                            (max-elements-stmt stmtsep)?
                            (ordered-by-stmt stmtsep)?
                            (status-stmt stmtsep)?
                            (description-stmt stmtsep)?
                            (reference-stmt stmtsep)?
                            ((typedef-stmt | grouping-stmt) stmtsep)*
                            (data-def-stmt stmtsep)*
                         '}'

key-stmt            =  key-keyword
                       sep
                       key-arg-str
                       stmtend

key-arg-str         =   DQUOTE key-arg DQUOTE
                      | SQUOTE key-arg SQUOTE
                      | key-arg

key-arg             = node-identifier
                      (sep node-identifier)*

unique-stmt         =  unique-keyword
                       sep
                       unique-arg-str
                       stmtend

unique-arg-str      =   DQUOTE unique-arg DQUOTE
                      | SQUOTE unique-arg SQUOTE
                      | unique-arg

unique-arg          = descendant-schema-nodeid
                      (sep descendant-schema-nodeid)*

choice-stmt         =  choice-keyword
                       sep
                       identifier-arg-str
                       optsep
                       (  ';'
                        | '{'
                             stmtsep
                             # these stmts can appear in any order
                             (when-stmt stmtsep)?
                             (if-feature-stmt stmtsep)*
                             (default-stmt stmtsep)?
                             (config-stmt stmtsep)?
                             (mandatory-stmt stmtsep)?
                             (status-stmt stmtsep)?
                             (description-stmt stmtsep)?
                             (reference-stmt stmtsep)?
                             ((short-case-stmt | case-stmt) stmtsep)*
                          '}'
                       )

short-case-stmt     =   container-stmt
                      | leaf-stmt
                      | leaf-list-stmt
                      | list-stmt
                      | anyxml-stmt

case-stmt           =  case-keyword
                       sep
                       identifier-arg-str
                       optsep
                        (  ';'
                         | '{'
                             stmtsep
                             # these stmts can appear in any order
                             (when-stmt stmtsep)?
                             (if-feature-stmt stmtsep)*
                             (status-stmt stmtsep)?
                             (description-stmt stmtsep)?
                             (reference-stmt stmtsep)?
                             (data-def-stmt stmtsep)*
                           '}'
                        )

anyxml-stmt         =  anyxml-keyword
                       sep
                       identifier-arg-str
                       optsep
                       (  ';'
                        | '{'
                             stmtsep
                             # these stmts can appear in any order
                             (when-stmt stmtsep)?
                             (if-feature-stmt stmtsep)*
                             (must-stmt stmtsep)*
                             (config-stmt stmtsep)?
                             (mandatory-stmt stmtsep)?
                             (status-stmt stmtsep)?
                             (description-stmt stmtsep)?
                             (reference-stmt stmtsep)?
                          '}'
                       )

uses-stmt           =  uses-keyword
                       sep
                       identifier-ref-arg-str
                       optsep
                       (  ';'
                        | '{'
                             stmtsep
                             # these stmts can appear in any order
                             (when-stmt stmtsep)?
                             (if-feature-stmt stmtsep)*
                             (status-stmt stmtsep)?
                             (description-stmt stmtsep)?
                             (reference-stmt stmtsep)?
                             (refine-stmt stmtsep)*
                             (uses-augment-stmt stmtsep)*
                          '}'
                       )

refine-stmt         =  refine-keyword
                       sep
                       refine-arg-str
                       optsep
                       ( ';'
                       | '{'
                           stmtsep
                           (  refine-container-stmts
                            | refine-leaf-stmts
                            | refine-leaf-list-stmts
                            | refine-list-stmts
                            | refine-choice-stmts
                            | refine-case-stmts
                            | refine-anyxml-stmts)
                          '}'
                       )

refine-arg-str      =   DQUOTE refine-arg DQUOTE
                      | SQUOTE refine-arg SQUOTE
                      | refine-arg

refine-arg          = descendant-schema-nodeid

refine-container-stmts = # these stmts can appear in any order
                            (must-stmt stmtsep)*
                            (presence-stmt stmtsep)?
                            (config-stmt stmtsep)?
                            (description-stmt stmtsep)?
                            (reference-stmt stmtsep)?

refine-leaf-stmts   = # these stmts can appear in any order
                        (must-stmt stmtsep)*
                        (default-stmt stmtsep)?
                        (config-stmt stmtsep)?
                        (mandatory-stmt stmtsep)?
                        (description-stmt stmtsep)?
                        (reference-stmt stmtsep)?

refine-leaf-list-stmts = # these stmts can appear in any order
                        (must-stmt stmtsep)*
                        (config-stmt stmtsep)?
                        (min-elements-stmt stmtsep)?
                        (max-elements-stmt stmtsep)?
                        (description-stmt stmtsep)?
                        (reference-stmt stmtsep)?

refine-list-stmts   = # these stmts can appear in any order
                        (must-stmt stmtsep)*
                        (config-stmt stmtsep)?
                        (min-elements-stmt stmtsep)?
                        (max-elements-stmt stmtsep)?
                        (description-stmt stmtsep)?
                        (reference-stmt stmtsep)?

refine-choice-stmts = # these stmts can appear in any order
                        (default-stmt stmtsep)?
                        (config-stmt stmtsep)?
                        (mandatory-stmt stmtsep)?
                        (description-stmt stmtsep)?
                        (reference-stmt stmtsep)?

refine-case-stmts   = # these stmts can appear in any order
                        (description-stmt stmtsep)?
                        (reference-stmt stmtsep)?


refine-anyxml-stmts = # these stmts can appear in any order
                        (must-stmt stmtsep)*
                        (config-stmt stmtsep)?
                        (mandatory-stmt stmtsep)?
                        (description-stmt stmtsep)?
                        (reference-stmt stmtsep)?

uses-augment-stmt   =   augment-keyword
                        sep
                        uses-augment-arg-str
                        optsep
                        '{' stmtsep
                            # these stmts can appear in any order
                            (when-stmt stmtsep)?
                            (if-feature-stmt stmtsep)*
                            (status-stmt stmtsep)?
                            (description-stmt stmtsep)?
                            (reference-stmt stmtsep)?
                            ((data-def-stmt stmtsep) | (case-stmt stmtsep))*
                        '}'

uses-augment-arg-str =   DQUOTE uses-augment-arg DQUOTE
                       | SQUOTE uses-augment-arg SQUOTE
                       | uses-augment-arg

uses-augment-arg    = descendant-schema-nodeid

augment-stmt        =  augment-keyword
                       sep
                       augment-arg-str
                       optsep
                       '{'
                            stmtsep
                            # these stmts can appear in any order
                            (when-stmt stmtsep)?
                            (if-feature-stmt stmtsep)*
                            (status-stmt stmtsep)?
                            (description-stmt stmtsep)?
                            (reference-stmt stmtsep)?
                            ((data-def-stmt stmtsep) | (case-stmt stmtsep))*
                       '}'

augment-arg-str     =  DQUOTE augment-arg DQUOTE
                     | SQUOTE augment-arg SQUOTE
                     | augment-arg

augment-arg         = absolute-schema-nodeid

unknown-statement   = prefix ':' identifier (sep string)? optsep
                      (';' | '{' unknown-statement2* '}')

unknown-statement2   = (prefix ':')? identifier (sep string)? optsep
                       (';' | '{' unknown-statement2* '}')

when-stmt           = when-keyword sep string optsep
                    (';' |
                     '{' stmtsep
                         # these stmts can appear in any order
                         (description-stmt stmtsep)?
                         (reference-stmt stmtsep)?
                      '}')

rpc-stmt            = rpc-keyword sep identifier-arg-str optsep
                    (';' |
                     '{' stmtsep
                         # these stmts can appear in any order
                         (if-feature-stmt stmtsep)*
                         (status-stmt stmtsep)?
                         (description-stmt stmtsep)?
                         (reference-stmt stmtsep)?
                         ((typedef-stmt | grouping-stmt) stmtsep)*
                         (input-stmt stmtsep)?
                         (output-stmt stmtsep)?
                     '}')

input-stmt          = input-keyword optsep
                    '{' stmtsep
                        # these stmts can appear in any order
                        ((typedef-stmt | grouping-stmt) stmtsep)*
                        (data-def-stmt stmtsep)*
                    '}'

output-stmt         = output-keyword optsep
                    '{' stmtsep
                        # these stmts can appear in any order
                        ((typedef-stmt | grouping-stmt) stmtsep)*
                        (data-def-stmt stmtsep)*
                    '}'

notification-stmt   = notification-keyword sep
                    identifier-arg-str optsep
                    (';' |
                     '{' stmtsep
                         # these stmts can appear in any order
                         (if-feature-stmt stmtsep)*
                         (status-stmt stmtsep)?
                         (description-stmt stmtsep)?
                         (reference-stmt stmtsep)?
                         ((typedef-stmt | grouping-stmt) stmtsep)*
                         (data-def-stmt stmtsep)*
                     '}')

deviation-stmt      = deviation-keyword sep
                      deviation-arg-str optsep
                     '{' stmtsep
                        # these stmts can appear in any order
                        (description-stmt stmtsep)?
                        (reference-stmt stmtsep)?
                        (deviate-not-supported-stmt |
                          (deviate-add-stmt | deviate-replace-stmt | deviate-delete-stmt)*)
                     '}'

deviation-arg-str   =   DQUOTE deviation-arg DQUOTE
                      | SQUOTE deviation-arg SQUOTE
                      | deviation-arg

deviation-arg       = absolute-schema-nodeid

deviate-not-supported-stmt = deviate-keyword sep
                            not-supported-keyword optsep
                            (';' |
                             '{' stmtsep
                             '}')

deviate-add-stmt    = deviate-keyword sep add-keyword optsep
                    (';' |
                     '{' stmtsep
                         (units-stmt stmtsep)?
                         (must-stmt stmtsep)*
                         (unique-stmt stmtsep)*
                         (default-stmt stmtsep)?
                         (config-stmt stmtsep)?
                         (mandatory-stmt stmtsep)?
                         (min-elements-stmt stmtsep)?
                         (max-elements-stmt stmtsep)?
                     '}')

deviate-delete-stmt = deviate-keyword sep delete-keyword optsep
                    (';' |
                     '{' stmtsep
                         (units-stmt stmtsep)?
                         (must-stmt stmtsep)*
                         (unique-stmt stmtsep)*
                         (default-stmt stmtsep)?
                     '}')

deviate-replace-stmt = deviate-keyword sep replace-keyword optsep
                    (';' |
                     '{' stmtsep
                         (type-stmt stmtsep)?
                         (units-stmt stmtsep)?
                         (default-stmt stmtsep)?
                         (config-stmt stmtsep)?
                         (mandatory-stmt stmtsep)?
                         (min-elements-stmt stmtsep)?
                         (max-elements-stmt stmtsep)?
                     '}')

# Ranges

range-arg-str       =   DQUOTE range-arg DQUOTE
                      | SQUOTE range-arg SQUOTE
                      | range-arg

range-arg           = range-part (optsep '|' optsep range-part)*

range-part          = range-boundary
                      (optsep '..' optsep range-boundary)*

range-boundary      =   min-keyword
                      | max-keyword
                      | integer-value
                      | decimal-value

# Lengths

length-arg-str      =   DQUOTE length-arg DQUOTE
                      | SQUOTE length-arg SQUOTE
                      | length-arg

length-arg          = length-part (optsep '|' optsep length-part)*

length-part         = length-boundary (optsep '..' optsep length-boundary)?

length-boundary     =  min-keyword
                     | max-keyword
                     | non-negative-integer-value

# Date

date-arg-str        =   DQUOTE date-arg DQUOTE
                      | SQUOTE date-arg SQUOTE
                      | date-arg

date-arg            =  < DIGIT4 '-' DIGIT2 '-' DIGIT2 >


# Schema Node Identifiers

schema-nodeid       =    absolute-schema-nodeid
                       | descendant-schema-nodeid

absolute-schema-nodeid = ('/' node-identifier)*

descendant-schema-nodeid = node-identifier
                           absolute-schema-nodeid

node-identifier     = (prefix ':')? identifier


# Instance Identifiers

instance-identifier = ('/' (node-identifier *predicate))*

predicate           = '[' WSP* (predicate-expr | pos) WSP* ']'

predicate-expr      = (node-identifier | '.') WSP* '=' WSP*
                      (string)

pos                 = non-negative-integer-value

# leafref path

path-arg-str        =   DQUOTE path-arg DQUOTE
                      | SQUOTE path-arg SQUOTE
                      | path-arg

path-arg            = absolute-path | relative-path

absolute-path       = ('/' (node-identifier *path-predicate))*

relative-path       = ('..' '/')* descendant-path

descendant-path     = node-identifier
                      (path-predicate* absolute-path)?

path-predicate      = '[' WSP* path-equality-expr WSP* ']'

path-equality-expr  = node-identifier WSP* '=' WSP* path-key-expr

path-key-expr       = current-function-invocation WSP* '/' WSP*
                      rel-path-keyexpr



rel-path-keyexpr    = ('..' WSP* '/' WSP*)*
                    (node-identifier WSP* '/' WSP*)*
                    node-identifier

#  Keywords

# statement keywords
anyxml-keyword           = 'anyxml'
argument-keyword         = 'argument'
augment-keyword          = 'augment'
base-keyword             = 'base'
belongs-to-keyword       = 'belongs-to'
bit-keyword              = 'bit'
case-keyword             = 'case'
choice-keyword           = 'choice'
config-keyword           = 'config'
contact-keyword          = 'contact'
container-keyword        = 'container'
default-keyword          = 'default'
description-keyword      = 'description'
enum-keyword             = 'enum'
error-app-tag-keyword    = 'error-app-tag'
error-message-keyword    = 'error-message'
extension-keyword        = 'extension'
deviation-keyword        = 'deviation'
deviate-keyword          = 'deviate'
feature-keyword          = 'feature'
fraction-digits-keyword  = 'fraction-digits'
grouping-keyword         = 'grouping'
identity-keyword         = 'identity'
if-feature-keyword       = 'if-feature'
import-keyword           = 'import'
include-keyword          = 'include'
input-keyword            = 'input'
key-keyword              = 'key'
leaf-keyword             = 'leaf'
leaf-list-keyword        = 'leaf-list'
length-keyword           = 'length'
list-keyword             = 'list'
mandatory-keyword        = 'mandatory'
max-elements-keyword     = 'max-elements'
min-elements-keyword     = 'min-elements'
module-keyword           = 'module'
must-keyword             = 'must'
namespace-keyword        = 'namespace'
notification-keyword     = 'notification'
ordered-by-keyword       = 'ordered-by'
organization-keyword     = 'organization'
output-keyword           = 'output'
path-keyword             = 'path'
pattern-keyword          = 'pattern'
position-keyword         = 'position'
prefix-keyword           = 'prefix'
presence-keyword         = 'presence'
range-keyword            = 'range'
reference-keyword        = 'reference'
refine-keyword           = 'refine'
require-instance-keyword = 'require-instance'
revision-keyword         = 'revision'
revision-date-keyword    = 'revision-date'
rpc-keyword              = 'rpc'
status-keyword           = 'status'
submodule-keyword        = 'submodule'
type-keyword             = 'type'
typedef-keyword          = 'typedef'
unique-keyword           = 'unique'
units-keyword            = 'units'
uses-keyword             = 'uses'
value-keyword            = 'value'
when-keyword             = 'when'
yang-version-keyword     = 'yang-version'
yin-element-keyword      = 'yin-element'

# other keywords

add-keyword              = 'add'
current-keyword          = 'current'
delete-keyword           = 'delete'
deprecated-keyword       = 'deprecated'
false-keyword            = 'false'
max-keyword              = 'max'
min-keyword              = 'min'
not-supported-keyword    = 'not-supported'
obsolete-keyword         = 'obsolete'
replace-keyword          = 'replace'
system-keyword           = 'system'
true-keyword             = 'true'
unbounded-keyword        = 'unbounded'
user-keyword             = 'user'


current-function-invocation = current-keyword WSP* '(' WSP* ')'

# Basic Rules

prefix-arg-str      =   DQUOTE prefix-arg DQUOTE
                      | SQUOTE prefix-arg SQUOTE
                      | prefix-arg

prefix-arg          = prefix

prefix              = identifier

identifier-arg-str  =   DQUOTE < identifier-arg > DQUOTE
                      | SQUOTE < identifier-arg > SQUOTE
                      | < identifier-arg >

identifier-arg      =  < identifier >

# An identifier MUST NOT start with (('X'|'x') ('M'|'m') ('L'|'l'))
identifier          = (ALPHA | '_')
                      (ALPHA | DIGIT | '_' | '-' | '.')*

identifier-ref-arg-str = DQUOTE identifier-ref-arg DQUOTE
                         | SQUOTE identifier-ref-arg SQUOTE
                         | identifier-ref-arg

identifier-ref-arg  = (prefix ':')? identifier

string              = WSP* (  '"' < [^\"]* > '"'
                            | "'" < [^\']* > "'") WSP*

jstring             =  (string optsep '+' optsep)* string

integer-value       =    ('-' non-negative-integer-value)
                        | non-negative-integer-value

non-negative-integer-value = '0' | positive-integer-value

positive-integer-value = (non-zero-digit DIGIT*)

zero-integer-value  = DIGIT*

stmtend             = ';' | '{' unknown-statement* '}'

sep                 = (WSP | line-break)*
                    # unconditional separator

optsep              = (WSP | line-break)*

stmtsep             = (WSP | line-break | unknown-statement)*

line-break          = CRLF | LF

comment             =    '//' (!line-break .)* line-break  # CPP/Java comment
                       | c-comment-begin (!c-comment-end .)* c-comment-end

c-comment-begin     =  '/*'
c-comment-end       =  '*/'

non-zero-digit      = [1-9]

decimal-value       = integer-value ("." zero-integer-value)

SQUOTE              = "'" # ' (Single Quote)

# RFC 5234 core rules.

ALPHA  = [a-zA-Z]

CR     = '\r' # carriage return

CRLF   = CR LF # Internet standard new line

DIGIT  = [0-9]

DQUOTE = '"' # " (Double Quote)

#HEXDIG = DIGIT | [a-f] # only lower-case a..f

HTAB   = '\t' # horizontal tab

LF     = '\n' # linefeed

SP     = ' ' # space

#VCHAR  = %x21-7E
# visible (printing) characters

WSP    = (SP | HTAB | comment) # whitespace

DIGIT2  = [0-9][0-9]
DIGIT4  = [0-9][0-9][0-9][0-9]

%%

#include "main.c"