Pretty indented stack traces

prettyTraces.js

/*
#
# Example final output:
#
# 1000 main
#   1000 workLoop
#     900 read
#       900 __sys_read
#     100 parse
#       100 strcmp
#
*/

function getStacktraces() {
     return [
        ["main","parse_args", "parse_entry"],
        ["main", "workloop", "select"],
        ["main", "workloop", "parse_data", "parse_entry"],
        ["main", "workloop", "select"]
     ]
}

function simplifyTraces(stacktraces) {
  var reducer = function(p, c) {
    var fnName = c;
    
    p[fnName] = p[fnName] || {};
    p[fnName].count = undefined === p[fnName].count? 1 : p[fnName].count + 1;
    p[fnName].next = p[fnName].next || {};
    return p[fnName].next; // to enable chaining
  }
  return stacktraces.reduce(function(p, stacktrace){
    stacktrace.reduce(reducer, p);
    return p; // since p = {} and will be passed by ref, everything side effects it
  }, {});
}


function pp(obj, initLevel) {
  Object.keys(obj).forEach(function(key) {
    function walk(obj, key, level) {
      if (undefined !== obj) {
        console.log('\t'.repeat(level), obj.count, key);
        pp(obj.next, ++level); // mutual recursion ftw
      }
    }

    walk(obj[key], key, initLevel || 0);
  });
}

pp(simplifyTraces(getStacktraces()), 0);

/* voila! */