INTERFACEThis is a standard format for passing around the description of a graph. These are graphs of the type that may include two or more distinct edges connecting the same pair of vertices, so an edge is known by a vertex number and an edge number within that node, rather than simply by a pair of vertices. For convenience of implementation of the intended clients, the number of edges to a single vertex is limited.GraphData ;
The data structure is a REF array of node records, of which each record is assumed to actually represent a node. Nodes are known by their indices in this array.
IMPORT Text, RealPoint, RealRect, Rd;
CONST
MaxEdge = 10;
TYPE
Vertex = CARDINAL;
EdgeIndex = [0..MaxEdge];
PointArray = REF ARRAY OF RealPoint.T;
EdgeRecord = RECORD
dest: Vertex;
destEdge: EdgeIndex;
present: BOOLEAN; (* FALSE => this is an empty slot, no edge here *)
segPoints: PointArray; (* bend points for segmented edges *)
etc: REFANY;
END;
VertexRecord = RECORD
name: Text.T;
x, y: REAL; (* coordinates for a visual representation *)
api: REAL;
edge: ARRAY EdgeIndex OF EdgeRecord;
present: BOOLEAN; (* FALSE => this is an empty slot, no vertex here *)
etc: REFANY;
END;
T = REF ARRAY OF VertexRecord;
PROCEDURE Copy(g: T): T;
Copy a GraphData structure, copying every REF in it except for the name and etc fields, which are transferred by reference, not copied.
PROCEDURE Expand(g: T; size: CARDINAL): T;
If NUMBER(g^) < size, then return a new GraphData structure, of which the first NUMBER(g^) fields are copied from the old one. Else return the old one unchanged. This copying differs from Copy in that the PointArray structures are transferred by reference, not copied.
PROCEDURE CountNodes(g: T): CARDINAL;
Count the number of nodes with present = TRUE
PROCEDURE BoundingBox(g: T): RealRect.T;
Compute the bounding box of all present vertices and segPoints
in g. PROCEDURE EdgeExists(g: T; a, b: CARDINAL): BOOLEAN;
Determine whether there is at least one edge between points a and b.
PROCEDURE RevPoints(in: PointArray): PointArray;
Produce a PointArray like <in> but in reverse order
PROCEDURE ExtractString(VAR line: Text.T): Text.T; PROCEDURE ReadGraph(rd: Rd.T):T; END GraphData.