link-grammar
v0.0.9
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Link grammar library node interface
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Link Grammar Parser
A node library which interfaces a well known link grammar native library
The point of this project is to make the library easier to use, especially in node!
Building Yourself
npm install
npm run make
Which will install, clean, compile, and test the project.
Documentation
Review list of Grammar Links here.
The parser is built using the awesome ffi library which allows us to communicate with a native library under the covers. Along with ffi, we also use ref library to reference the native objects used by the library.
ffi = require 'ffi'
ref = require 'ref'
Struct = require 'ref-struct'
_ = require 'underscore'
Easier references to base types of data.
pointerType = 'pointer'
string = ref.types.CString
int = ref.types.int
These are just references to different native structs, which are all just pointers because we never use their actual referenced object.
ParseOptions = pointerType
Dictionary = pointerType
Sentence = pointerType
Linkage = pointerType
CNode = Struct(
label: ref.types.CString
child: pointerType
next: pointerType
start: ref.types.int
end: ref.types.int
)
CNodePtr = ref.refType CNode
Here are the templates for the native functions we will use.
apiTemplate =
parse_options_create: [ ParseOptions, [ ] ]
parse_options_set_verbosity: [ ref.types.void, [ ParseOptions, int ] ]
dictionary_create: [ Dictionary, [ string, string, string, string ] ]
sentence_create: [ Sentence, [ string, Dictionary ] ]
sentence_parse: [ int, [ Sentence, ParseOptions ] ]
sentence_length: [ int, [ Sentence ] ]
sentence_get_word: [ string, [ Sentence, int ] ]
linkage_create: [ Linkage, [ int, Sentence, ParseOptions ] ]
linkage_print_diagram: [ string, [ Linkage ] ]
linkage_constituent_tree: [ CNodePtr, [ Linkage ] ]
linkage_print_constituent_tree: [ string, [ Linkage, int] ]
linkage_get_num_links: [ int, [ Linkage ] ]
linkage_get_link_label: [ string, [ Linkage, int ] ]
linkage_get_link_llabel: [ string, [ Linkage, int ] ]
linkage_get_link_rlabel: [ string, [ Linkage, int ] ]
linkage_get_word: [ string, [ Linkage, int ] ]
linkage_get_link_lword: [ int, [ Linkage, int ] ]
linkage_get_link_rword: [ int, [ Linkage, int ] ]
Load the library.
libPath = __dirname + '/../lib/libparser'
lib = ffi.Library libPath, apiTemplate
defaultDataPath = __dirname + '/../data/'
Utility functions...
getNodePtrFromPtr = (ptr) ->
tempPtr = ref.alloc CNodePtr
ref.writePointer tempPtr, 0, ptr
tempPtr.deref()
Default configuration for data paths.
defaultConfig =
dictPath: defaultDataPath + '4.0.dict'
ppPath: defaultDataPath + '4.0.knowledge'
consPath: defaultDataPath + '4.0.constituent-knowledge'
affixPath: defaultDataPath + '4.0.affix'
verbose: false
Main parser class which interfaces the native library to make it very simple to get link grammar data from an input string.
class LinkGrammar
A few utility methods for the parser.
constructor: (config) ->
@config = _.extend config or {}, defaultConfig
@options = lib.parse_options_create()
lib.parse_options_set_verbosity @options, (if @config.verbose then 1 else 0)
@dictionary = lib.dictionary_create @config.dictPath, @config.ppPath, @config.consPath, @config.affixPath
Parse input, and return linkage.
parse: (input, index) ->
sentence = lib.sentence_create input, @dictionary
numLinkages = lib.sentence_parse sentence, @options
new Linkage lib.linkage_create index or 0, sentence, @options
Linkage class which allows for more specific parsing of grammar.
class Linkage
constructor: (@linkage) ->
@links = @getLinks()
@tree = @getTree()
@words = @getWords()
Recursive tree builder method.
buildNode: (node) ->
n =
label: node.label
if not ref.isNull node.child
n.child = @buildNode getNodePtrFromPtr(node.child).deref()
if not ref.isNull node.next
n.next = @buildNode getNodePtrFromPtr(node.next).deref()
n
Get a tree of grammar nodes which map out how the input sentence is structered.
getTree: ->
rootPtr = lib.linkage_constituent_tree @linkage
@buildNode rootPtr.deref(), @linkage
Get array of grammar links based on linkage.
getLinks: ->
_(lib.linkage_get_num_links @linkage).times ((index) ->
leftIndex = lib.linkage_get_link_lword @linkage, index
rightIndex = lib.linkage_get_link_rword @linkage, index
link =
label: lib.linkage_get_link_label @linkage, index
left:
label: lib.linkage_get_link_llabel @linkage, index
word: lib.linkage_get_word @linkage, leftIndex
index: leftIndex
right:
label: lib.linkage_get_link_rlabel @linkage, index
word: lib.linkage_get_word @linkage, rightIndex
index: rightIndex
if link.left.word.indexOf '.' isnt -1
temp = link.left.word.split '.'
link.left.word = temp[0]
link.left.type = temp[1]
if link.right.word.indexOf '.' isnt -1
temp = link.right.word.split '.'
link.right.word = temp[0]
link.right.type = temp[1]
link
), @
Get parsed words with their grammar type and index
getWords: ->
_.chain(@links)
.map (link) -> [link.left, link.right]
.flatten()
.uniq (link) -> link.word
.value()
Get list of links by specific label type
linksByLabel: (labelPattern) ->
labelPattern = new RegExp labelPattern if typeof labelPattern is 'string'
@links.filter (link) ->
labelPattern.test link.left.label or labelPattern.test link.right.label
Get list of connector links for a specific word
getConnectorWords: (common) ->
words = []
@links.forEach (link) ->
if link.left.word is common
words.push
source: link.left
target: link.right
if link.right.word is common
words.push
source: link.right
target: link.left
words