Min Essential Knots

API ID: MinEssentialKnots
Languages: Ada, C#, C++, Java, Rust
Targets: Functions, Packages, Subprograms

Minimum Knots after structured programming constructs have been removed.

Knots and Essential Complexity both start by removing well-structured (single-entry, single-exit) subgraphs from the control-flow graph. Min Essential Knots is just the Knots count of what's left after that reduction, instead of the raw (unreduced) graph.

For example:

void knotsDemo() {
  while (1) {
    if (a)
      break;
    if (b || c) {
      if (d || e) {
      }
      else {
        if (i)
          dosomething();
        else if (j)
          dosomething();
        else if (k)
          dosomething();
        else {}
      }
    }
  }
}

Reducing knotsDemo collapses the well-structured if (b || c) { ... } chain away, leaving just while (1) { if (a) break; }. That reduced graph has 2 knots (the loop's back edge crossing the break's forward jump), so Min Essential Knots is 2 — much lower than the 6 knots in the unreduced function.

See Max Essential Knots, which also accounts for crossings that reduction hides.

Targets By Language:

• Ada: Type, Entry, Function, Package, Procedure, Protected, Task
• C#: Method
• C++: Function
• Java: Method
• Rust: Function

Configuration:

• This metric can be enabled from "Project Configuration/Metrics/Complexity" with the "Knots" option.