README_FS

'Shakti Standard Format of Feature Structure':
	E.g.: <af=ram,n,m,s,3,0,,>|<af=ram,v,m,s,3,0,,/attr1=val1/attr2=val2/attr3=<attr4=val4|<attr5=val5>>>

'Representaion of the Structure':
	A Feature structure is represented by a hash.
	All the attributes in the feature structure make the keys of the hash.
	The value of the key is a reference to a OR node (i.e. an array).
	Each field of the OR node (array) contains either reference to a hash (i.e. another feature structure)
	or a value.
	
	User when he calls read_FS($string) he gets the reference to an or node (i.e. a collection of feature structures).

OR node which can have one/more feature structures
        <af=,,,,/a1=v1/a2=v2>|<af=,,,,/b1=w1/b2=w2>

$ORNode is reference to an array
$ORNode =>  --  --
       | V1 |
       | V2 |           Vn = { Reference to Feature Structure (Ref to a hash) (or) string }
       | .. |
       | Vn |
       --  --

$FS is a reference to a hash
$FS =>

        --           --
        | attr1  val1 |
        | attr2  val2 |         valn = { $ORNode }
        |     ...     |
        | attrn  valn |
        --           --



#% read_FS($string)  --> reference to an OR node (array).
	 $string is the feature structure (to be loaded) in the new shakti standard format.
	 reference to an OR node (array) is returned.

#% read_FS_old($string)  --> reference to an OR node (array).
	 $string is the feature structure in the old shakti standard format.
	 reference to an OR node (array) is returned. 
 
#% get_values($featurePath,$FSreference)	--> An OR node (array) containg the values of that attribute.
	 $FSreference is the reference to an OR node (array) of the feature structure.
	 An OR node is returned containing all possible values for that specified feature path. 

#% get_values_2($featurePath,$FSreference)	--> An array containg the matched values.
	 $FSreference is the reference to a single feature structure.
	 An OR node is returned containing all possible values for that specified feature path.

#% get_attributes($FSReference)		-> array containing the attributes for that feature structure
	 $FSReference is the reference to a single feature structure (i.e. reference to a hash ).
	 array containing the attributes for that feature structure is returned. 

#% get_path_values($attr,$fs)	--> 2D array of values and paths.
	 $fs is the reference to an OR node (array) with one or more Feature Structure present in it.
	 A 2D array of values and paths is returned.
	 field 0 of that array contains the path.
	 field 1 of that array contains the corresponding value. <Changes made to the value here will not be reflected>.

#% get_path_values_2($attr,$fs)	--> 2D array of values and paths.
	 $fs is the reference to a single feature structure. (i.e. reference to a hash)
	 a 2D array of values and pathss is returned
	 field 0 of that array contains the path.
	 field 1 of that array contains the corresponding value. <Changes made to the value here will not be reflected>.

#% copyFS($fs) --> Reference of a new FS
	 $fs is the reference to a single feature structure
	 A reference to a new copied feature structure is returned.

#% add_attr_val($featurePath,$value,$FSReference)	--> -nil-
	 $FSReference is the reference to an OR node (array).
	 $value is a reference to an OR node (array) which will be the value of the attribute mentioned by $featurePath.
	 Nothing is returned.

#% add_attr_val_2($featurePath,$value,$FSReference)	--> -nil-
	 $FSReference is the reference to a single feature structure (i.e reference to a hash).
	 $value and $featurePath have the same meaning as specified above.

#% update_attr_val($featurePath,$val,$FSReference)	--> -nil-
	 $FSReference is the reference to an OR Node (array)
	 The value specified by the featurepath willll be changed to the new val ($val)
	 $val is the reference to another OR node (array).

#% update_attr_val_2($featurePath,$val,$FSReference)	--> -nil-
	 $FSReference is the reference to a single feature structure (Reference to a hash).
	 The value specified by the featurepath willll be changed to the new val ($val)
	 $val is the reference to another OR node (array).

#% del_attr_val($featurePath,$FSReference)
	 $FSReference is the reference to an OR node (array).
	 Deletes the value of the attribute specified by $featurePath.

#% del_attr_val_2($featurePath,$FSReference)
	 $FSReference is the reference to a single feature structure (i.e. reference to a hash).
	 Deletes the value of the attribute specified by $featurePath.

#% unify($fs1,$fs2)	--> $fs3;
	 $fs1 and $fs2 are references to two OR nodes containing one or more feature structures,
	 $fs3 is either -1 or a reference to a new OR node of feature structures.
	 -1 is returned in the case that the featurestructures cannot be unified.
	 Though provision has been provided for passing OR nodes as the arguments, 
	 each OR node passed in the argument should
	 refer to only one feature structure.

#% unify_2($fs1,$fs2)	--> $fs3;
	 $fs1 and $fs2 are references to two feature structures (i.e. reference to hashes),
	 $fs3 is either -1 or a reference to a new OR node of feature structures.
	 -1 is returned in the case that the featurestructures cannot be unified.

#% merge($fs1,$fs2)	-->	-nil-
	 $fs1 and $fs2 are references to OR nodes containing multiple possible feature structures.
	 Changes the values of $fs1 to those of $fs2 for all the common attributes of fs1 and fs2
	 Rest of the values of $fs1 are left untouched.

#% merge_2($fs1,$fs2)	-->	-nil-
	 $fs1 and $fs2 are references to single feature structures.
	 Changes the values of $fs1 to those of $fs2 for all the common attributes of fs1 and fs2
	 Rest of the values of $fs1 are left untouched.

#% load_hash()	--> Reference to a hash
	 Loads the string passed into a hash 
	 Reference to that hash is returned.

#% printFS_SSF($fs)	--> -nil-
	 $fs is a reference to an OR node containing one or more feature structures.
	 prints the structure in the standard format. 

#% printFS_SSF_2($fs)	--> -nil-
	 $fs is a reference to a single feature structure (i.e. reference to a hash)
	 prints the structure in the standard format. 

#% make_string($FSReference)	--> 	-$string-
	 $FSReference is the reference to an OR node.
	 $string is the feature structure in the standard format.

#% make_string_2($FSReference)	--> 	-$string-
	 $FSReference is the reference to a single feature structure (i.e reference to a hash).
	 $string is the feature structure in the standard format.

#% prune_FS($featurePath,$fieldNumber,$FSReference)	--> +1/-1
	 $FSReference is the reference to an OR node.
	 Deletes the feature structure or value from the OR node (array) , which is the value of the attribute specified by
	 $featurePath.
	 +1 indicates successful completion of the function
	 -1 indicates that such a feature path does not exist.

#% prune_FS_2($featurePath,$fieldNumber,$FSReference)	--> +1/-1
	 $FSReference is the reference to a single feature structure.
	 Deletes the feature structure or value from the OR node (array) , which is the value of the attribute specified by
	 $featurePath.
	 +1 indicates successful completion of the function
	 -1 indicates that such a feature path does not exist.

#% get_fs_reference($ref_to_array,$index_feature_structure)
	 $ref_to_array is the reference to an OR node (array).
	 $index_... is the field you want from that array.

#% get_num_fs($ref_to_array)  --> number of feature structures in that reference passed (Or values also)
	 $ref_to+array is the reference to an OR node (array).
 
#% printFS_SSF_old($fs)	--> -nil-
	 $fs is a reference to an OR node.
	 prints the feature structure in the old shakti format.

#% make_string_old($fs)	--> -$string-
	 $fs is a reference to an OR node.
	 makes the feature structure in the old shakti format.
	 And that string is returned.