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Documentation Index

Fetch the complete documentation index at: https://mehen.ophi.dev/llms.txt

Use this file to discover all available pages before exploring further.

This page walks through implementing the LOC family — loc.sloc, loc.ploc, loc.lloc, loc.cloc, loc.blank — for a new language analyzer.

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Five LOC variants

/*
Instruction: Implement factorial function
For extra credits, do not use mutable state or imperative loops.
 */

/// Factorial: n! = n*(n-1)*(n-2)*...*3*2*1
fn factorial(num: u64) -> u64 {

    // use `product` on `Iterator`
    (1..=num).product()
}
The example above will be used to illustrate each LOC metric.

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SLOC

A straight count of all lines in the file including code, comments, and blank lines. Value: 11.

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PLOC

A count of the instruction lines of code contained in the source code. This includes any brackets or similar syntax on a new line. Comments and blank lines are excluded. Value: 3.

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LLOC

The “logical” line count is the number of statements in the code. What a statement is depends on the language. In the example there is only a single statement — the function call of product with the Iterator as its argument. Value: 1.

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CLOC

Number of comments in the code. The type of comment does not matter — single line, block, or doc. Value: 6.

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Blank

Whitespace-only lines. Value: 2.

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Implementation

To implement the LOC metrics for a new language, contribute the appropriate node-kind matchers in your analyzer crate’s loc module. mehen’s mehen-metrics::loc exposes the LocStats accumulator that all analyzers feed. The accumulator pattern:
  1. Walk the parse tree per-line, deciding whether each line is code, comment, blank, or mixed.
  2. For LLOC, walk the AST and count nodes whose kind matches the language’s statement kinds (expression_statement, if_statement, for_statement, …).
  3. Emit LocStats on file-close; mehen-metrics::halstead_routing::insert_loc_metrics writes the resulting loc.* keys.
See crates/mehen-metrics/src/loc.rs and the per-language loc modules for live examples.

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See also