Analysis Traversal Guide

This guide explains how to traverse BSharp AST statements and expressions in analysis passes using the current framework.

• Source files:
  • src/bsharp_analysis/src/framework/walker.rs
  • src/bsharp_analysis/src/framework/query/
  • src/bsharp_analysis/src/passes/*

Statement traversal

Use AstWalker for single-pass traversal with the Visit trait, or the Query API for typed filtering.

Example using AstWalker + Visit to count if statements:

#![allow(unused)]
fn main() {
use bsharp_analysis::framework::{AstWalker, Visit, NodeRef, AnalysisSession};

struct CountIfs { pub ifs: usize }
impl Visit for CountIfs {
    fn enter(&mut self, node: &NodeRef, _session: &mut AnalysisSession) {
        if let NodeRef::Statement(s) = node {
            if matches!(s, bsharp_syntax::statements::statement::Statement::If(_)) {
                self.ifs += 1;
            }
        }
    }
}
}

Expression traversal

Use Query for typed expression searches:

#![allow(unused)]
fn main() {
use bsharp_analysis::framework::{NodeRef, Query};
use bsharp_syntax::expressions::AwaitExpression;

let await_count = Query::from(NodeRef::CompilationUnit(&cu))
    .of::<AwaitExpression>()
    .count();
}

Putting it together

When analyzing methods, you typically:

• Parse the compilation unit and build the analysis session.
• For each method body (a Statement::Block), compute metrics by walking statements and expressions.

Example (from ControlFlowPass pattern):

#![allow(unused)]
fn main() {
use bsharp_analysis::artifacts::cfg::{ControlFlowIndex, MethodControlFlowStats};
use bsharp_syntax::statements::statement::Statement;

fn stats_for_method(body: Option<&Statement>) -> MethodControlFlowStats {
    let complexity = match body { Some(s) => 1 + decision_points(s), None => 1 };
    let max_nesting = calc_max_nesting(body, 0);
    let exit_points = count_exit_points(body);
    let statement_count = count_statements(body);
    MethodControlFlowStats { complexity, max_nesting, exit_points, statement_count }
}
}

See src/bsharp_analysis/src/metrics/shared.rs for helpers like decision_points, max_nesting_of, count_statements and src/bsharp_analysis/src/passes/control_flow.rs for usage.

See Also

• Cookbooks
• Query Cookbook

Tips

• Keep walkers side-effect free; accumulate results in closures.
• Prefer small, focused passes that use the walkers rather than embedding traversal in each pass.
• If a construct is not being traversed, add it to the walker first to avoid duplicated traversal logic.