This module defines the various attributes that different parts of a GraphViz graph can have. These attributes are based on the documentation found at: http://graphviz.org/doc/info/attrs.html

For more information on usage, etc. please see that document.

A summary of known current constraints/limitations/differences:

• There might still be a few cases where quotes are still not escaped/parsed correctly; if you find such a situation, please let me know; however, you should be able to use String values directly without having to worry about when quotes are required or extra escaping of quote characters as PrintDot and ParseDot instances for String should take care of that for you.
• Note that for an edge, in Dot parlance if the edge goes from A to B, then A is the tail node and B is the head node (since A is at the tail end of the arrow).
• When parsing named Color values, the entire value entered is kept as-is; this library as yet has no understanding of different color schemes, etc.
• ColorList and PointfList are defined as actual lists (but LayerList is not). Note that for the Color Attribute for node values, only a single Color is valid; edges are allowed multiple colors with one spline/arrow per color in the list (but you must have at least one Color in the list). This might be changed in future.
• Style is implemented as a list of StyleItem values; note that empty lists are not allowed.
• A lot of values have a possible value of none. These now have custom constructors. In fact, most constructors have been expanded upon to give an idea of what they represent rather than using generic terms.
• PointF and Point have been combined, and feature support for pure Int-based co-ordinates as well as Double ones (i.e. no floating point-only points for Point). The optional ! and third value for Point are not available.
• Rect uses two Point values to denote the lower-left and top-right corners.
• The two LabelLoc attributes have been combined.
• The defined LayerSep is not used to parse LayerRange or LayerList; the default ([' ', ':', '\t']) is instead used.
• SplineType has been replaced with [Spline].
• Only polygon-based Shapes are available.
• PortPos only has the CompassPoint option, not PortName[:CompassPoint] (since record shapes aren't allowed, and parsing HTML-like labels could be problematic).
• Not every Attribute is fully documented/described. However, all those which have specific allowed values should be covered.
• Deprecated Overlap algorithms are not defined.

Some Attributes (mainly label-like ones) take a String argument that allows for extra escape codes. This library doesn't do any extra checks or special parsing for these escape codes, but usage of EscString rather than String indicates that the GraphViz tools will recognise these extra escape codes for these Attributes.

The extra escape codes include (note that these are all Strings):

\N

Replace with the name of the node (for Node Attributes).

\G

Replace with the name of the graph (for Node Attributes) or the name of the graph or cluster, whichever is applicable (for Graph, Cluster and Edge Attributes).

\E

Replace with the name of the edge, formed by the two adjoining nodes and the edge type (for Edge Attributes).

\T

Replace with the name of the tail node (for Edge Attributes).

\H

Replace with the name of the head node (for Edge Attributes).

\L

Replace with the object's label (for all Attributes).

Also, if the Attribute in question is Label, HeadLabel or TailLabel, then \n, \l and \r split the label into lines centered, left-justified and right-justified respectively.