Mercury.Syntax.Edge Class Reference

Represents an edge in the chart created by the ChartParser. This is an immutable class.
The Edge contains four values:
More...

Inheritance diagram for Mercury.Syntax.Edge:

Public Member Functions
	Edge (Rule rule, int dot, int left, int right)
	Creates a new edge. If the constructor does not throw any exception, the edge is guaranteed to be valid. More...
bool	IsValid ()
	Determines whether this edge is valid. More...
override bool	Equals (object obj)
override int	GetHashCode ()
override string	ToString ()
bool	Equals (Edge other)
int	CompareTo (Edge other)
	Compares the edge with another edge. Defines a lexicographical order as follows: More...

Properties
Rule	Rule [get, set]
	The source rule. More...
int	Dot [get, set]
	Position of the dot. More...
int	Left [get, set]
	Left node number. More...
int	Right [get, set]
	Right node number. More...
bool	IsActive [get, set]
	Determines whether the edge is active. More...
bool	IsPassive [get, set]
	Complement of IsActive (convenience property). More...
Symbol	NextSymbol [get, set]
	Returns the next symbol after the dot. The edge must be active, otherwise is null. More...

Detailed Description

Represents an edge in the chart created by the ChartParser. This is an immutable class.
The Edge contains four values:

• source rule

  - rule that possibly created a part of sentence
  

• dot        

  - position in the rule
  

• left       

  - number of left node in the chart
  

• right      

  - number of right node in the chart
  

Edge is usually written in the form (l, r) A -> alpha . beta which means that this edge "covers" tokens l to r in the input (alpha) and is yet to cover beta.

Edge is said to be active iff beta is not empty (that is, dot < n). Otherwise the rule is said to be passive.

For an edge to be valid the following conditions must hold:

1. source rule is valid,
   
2. 
   a) dot == 0 if the source rule is an epsilon rule
   b) 0 <= dot <= n otherwise (n is the count of RHS symbols)
   
3. left <= right

Definition at line 37 of file Edge.cs.

Constructor & Destructor Documentation

Mercury.Syntax.Edge.Edge	(	Rule	rule,
		int	dot,
		int	left,
		int	right
	)

Creates a new edge. If the constructor does not throw any exception, the edge is guaranteed to be valid.

Parameters

rule	The source rule.
dot	Position of the dot.
left	Left node number.
right	Right node number.

Exceptions

System.ArgumentNullException	When the source rule is null.
Mercury.Exceptions.InvalidEdgeException	When the edge is not valid.

Definition at line 55 of file Edge.cs.

Member Function Documentation

int Mercury.Syntax.Edge.CompareTo

(

Edge

other

)

Compares the edge with another edge. Defines a lexicographical order as follows:

1. compare left node numbers
2. compare right node numbers
3. lexicobraphically compare source rules
4. compare dot positions

Parameters

other

Another edge

Returns

A value that indicates the relative order of the edges. See IComparable.

Definition at line 179 of file Edge.cs.

override bool Mercury.Syntax.Edge.Equals

(

object

obj

)

Definition at line 124 of file Edge.cs.

bool Mercury.Syntax.Edge.Equals

(

Edge

other

)

Definition at line 155 of file Edge.cs.

override int Mercury.Syntax.Edge.GetHashCode

(

)

Definition at line 130 of file Edge.cs.

bool Mercury.Syntax.Edge.IsValid

(

)

Determines whether this edge is valid.

Returns

true if the edge is valid, false otherwise.

Definition at line 117 of file Edge.cs.

override string Mercury.Syntax.Edge.ToString

(

)

Definition at line 133 of file Edge.cs.

Property Documentation

int Mercury.Syntax.Edge.Dot

getset

Position of the dot.

Definition at line 76 of file Edge.cs.

bool Mercury.Syntax.Edge.IsActive

getset

Determines whether the edge is active.

true if the edge is active, false otherwise

Definition at line 91 of file Edge.cs.

bool Mercury.Syntax.Edge.IsPassive

getset

Complement of IsActive (convenience property).

true if the rule is not active false otherwise

Definition at line 100 of file Edge.cs.

int Mercury.Syntax.Edge.Left

getset

Left node number.

Definition at line 79 of file Edge.cs.

Symbol Mercury.Syntax.Edge.NextSymbol

getset

Returns the next symbol after the dot. The edge must be active, otherwise is null.

Definition at line 106 of file Edge.cs.

int Mercury.Syntax.Edge.Right

getset

Right node number.

Definition at line 82 of file Edge.cs.

Rule Mercury.Syntax.Edge.Rule

getset

The source rule.

Definition at line 73 of file Edge.cs.

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The documentation for this class was generated from the following file:

• Mercury/Mercury/Syntax/Edge.cs