nestlog -- logging with automatic call-graph indenting

Nestlog is a lightweight header-only library for console logging.

Features

• header-only; nothing to link
• easy-to-read format uses indenting to show call structure. indentation has user-controlled upper limit to preserve readability with deeply nested call graphs
• colorized output using vt100 color codes (ansi or xterm)
• automatically captures + displays timestamp, function name and code location. supports several function-name formats to reflect tradeoff readability for precision
• application code may issue logging code that contains embedded newlines and/or color escapes; logger preserves indentation.
• logger is 'truthy' -> only pay for formatting when entry points is enabled.
• also provides family of convenience stream-inserters

Examples

1

/* examples/ex1/ex1.cpp */

#include "nestlog/scope.hpp"

void A(int x) {
    XO_SCOPE(log);  // i.e. xo::scope log("A");

    log("enter ", ":x ", x);
}

int
main(int argc, char ** argv) {
    A(66);
}

output:

+A
 enter :x 66
-A

2

/* examples ex2/ex2.cpp */

#include "nestlog/scope.hpp"

using namespace xo;

int
fib(int n) {
    scope log(XO_ENTER0(info), ":n ", n);

    int retval = 1;

    if (n >= 2) {
        retval = fib(n - 1) + fib(n - 2);
        log && log(":n ", n);
    }

    log.end_scope("<- :retval ", retval);

    return retval;
}

int
main(int argc, char ** argv) {
    log_config::min_log_level = xo::log_level::info;
    log_config::indent_width = 4;

    int n = 4;

    scope log(XO_ENTER0(info), ":n ", 4);

    int fn = fib(n);

    log && log(":n ", n);
    log && log("<- :fib(n) ", fn);
}

output:

20:13:12.992909 +(0) main :n 4                                   [ex2.cpp:30]
20:13:12.992968     +(1) fib :n 4                                [ex2.cpp:9]
20:13:12.992986         +(2) fib :n 3                            [ex2.cpp:9]
20:13:12.992999             +(3) fib :n 2                        [ex2.cpp:9]
20:13:12.993002                 +(4) fib :n 1                    [ex2.cpp:9]
20:13:12.993012                 -(4) fib <- :retval 1
20:13:12.993022                 +(4) fib :n 0                    [ex2.cpp:9]
20:13:12.993032                 -(4) fib <- :retval 1
                                :n 2
20:13:12.993049             -(3) fib <- :retval 2
20:13:12.993059             +(3) fib :n 1                        [ex2.cpp:9]
20:13:12.993069             -(3) fib <- :retval 1
                            :n 3
20:13:12.993085         -(2) fib <- :retval 3
20:13:12.993095         +(2) fib :n 2                            [ex2.cpp:9]
20:13:12.993105             +(3) fib :n 1                        [ex2.cpp:9]
20:13:12.993115             -(3) fib <- :retval 1
20:13:12.993124             +(3) fib :n 0                        [ex2.cpp:9]
20:13:12.993134             -(3) fib <- :retval 1
                            :n 2
20:13:12.993145         -(2) fib <- :retval 2
                        :n 4
20:13:12.993155     -(1) fib <- :retval 5
                    :n 4
                    <- :fib(n) 5
20:13:12.993172 -(0) main