How do you write a program in c plus plus language to draw a precedence diagram for assembly?

Answer 1

Precedence assembly diagrams are used to show all the steps that must be undertaken in order to produce the complete assembly of a component from its component parts. Some steps must be completed before others can begin (serial assembly), but there will sometimes be two or more steps that can be completed in any order (parallel assembly).

In order to model the sequence of events we need a node object that holds a single step in the assembly, along with two node pointer lists. The first list points to all the nodes that must be completed before this node's step can begin, while the second list points to all the nodes that may be started once this node's step is complete. We call these lists the parent list and the child list respectively. Every assembly has one root node which has no parents, and one leaf node with no children. These nodes mark the start and end of the assembly, and all other nodes interlink directly or indirectly with these two nodes to form a lattice.

The simplest lattice is the serial assembly lattice, where one node leads directly to another in sequence. The minimum number of nodes in a serial assembly is three: a root, a child step and a leaf.

The next simplest lattice is the diamond formation where there are four nodes in total: a root, two child steps and a leaf. This forms a simple parallel assembly lattice because the two child nodes may be completed in any order, but only after the root is complete. Moreover, the leaf cannot begin until both children are complete.

More complex assemblies can be catered for by adding more child steps and by combining serial and parallel formations. Note that each node within the lattice forms the root of a component part within the completed assembly. Thus the lattice provides automatic sub-grouping of each component part.

The only thing missing is a completion field in each node. This is necessary when drawing your diagram because children with two or more parents can only begin when all their parents are complete. To achieve this you simply need a boolean flag that is initially false. As you draw your diagram, begin at the root, process it and mark as complete. Now repeatedly traverse from the root using depth-first traversal to locate the first incomplete node. If any of its parents are incomplete, traverse to the first incomplete parent and check its parents. Eventually you will locate an inmcomplete node where all the parents are marked complete, at which point you can process the node and mark it as complete. Start over at the root to locate the next node. Eventually you will arrive at the leaf and all its parents will be marked complete. After processing the leaf, the assembly is complete.