object

`halstead_metric(Stroud)`

Stroud - Coefficient for computing the time required to program.

Computes Halstead complexity numbers for an entity.

Author: Paulo Moura
Version: 0:8:0
Date: 2022-05-05

Compilation flags:

static, context_switching_calls

Imports:

public code_metrics_utilities

public code_metric

Uses:

list
numberlist
pairs

Remarks:

Definition of operators: Predicates declared, user-defined, and called are interpreted as operators. Built-in predicates and built-in control constructs are ignored.

Definition of operands: Predicate arguments are abstracted and interpreted as operands. Note that this definition of operands is a significant deviation from the original definition, which used syntactic literals.

Pn: Number of distinct predicates (declared, defined, called, or updated).

PAn: Number of predicate arguments (assumed distinct).

Cn: Number of predicate calls/updates + number of clauses.

CAn: Number of predicate call/update arguments + number of clause head arguments.

EV: Entity vocabulary: EV = Pn + PAn.

EL: Entity length: EL = Cn + CAn.

V: Volume: V = EL * log2(EV).

D: Difficulty: D = (Pn/2) * (CAn/An).

E: Effort: E = D * V.

T: Time required to program: T = E/k seconds (k is the Stroud number; defaults to 18).

B: Number of delivered bugs: B = V/3000.

Entity score: Represented as the compound term pn_pan_cn_can_ev_el_v_d_e_t_b/11.