redundant code removed - clinte - Community notes board for shared UNIX systems

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author	Ben Morrison <ben@gbmor.dev>	2019-08-30 12:54:40 -0400
committer	Ben Morrison <ben@gbmor.dev>	2019-08-30 12:54:40 -0400
commit	e42a73688772f35cf0e97865c15e5bb10b4e2d2b (patch)
tree	5ead256365248e525a6f397c8bad077feeb3e5f3 /src/main.rs
parent	b278ba66fd7975249e0b90055cd5a46034b072b9 (diff)
download	clinte-e42a73688772f35cf0e97865c15e5bb10b4e2d2b.tar.gz

redundant code removed

Diffstat (limited to 'src/main.rs')

-rw-r--r--

src/main.rs

1 files changed, 0 insertions, 3 deletions

//: The goal of layers is to make programs more easy to understand and more //: malleable, easy to rewrite in radical ways without accidentally breaking //: some corner case. Tests further both goals. They help understandability by //: letting one make small changes and get feedback. What if I wrote this line //: like so? What if I removed this function call, is it really necessary? //: Just try it, see if the tests pass. Want to explore rewriting this bit in //: this way? Tests put many refactorings on a firmer footing. //: //: But the usual way we write tests seems incomplete. Refactorings tend to //: work in the small, but don't help with changes to function boundaries. If //: you want to extract a new function you have to manually test-drive it to //: create tests for it. If you want to inline a function its tests are no //: longer valid. In both cases you end up having to reorganize code as well as //: tests, an error-prone activity. //: //: In response, this layer introduces the notion of domain-driven *white-box* //: testing. We focus on the domain of inputs the whole program needs to //: handle rather than the correctness of individual functions. All white-box //: tests invoke the program in a single way: by calling run() with some //: input. As the program operates on the input, it traces out a list of //: _facts_ deduced about the domain: //: trace("label") << "fact 1: " << val; //: //: Tests can now check for these facts in the trace: //: CHECK_TRACE_CONTENTS("label", "fact 1: 34\n" //: "fact 2: 35\n"); //: //: Since we never call anything but the run() function directly, we never have //: to rewrite the tests when we reorganize the internals of the program. We //: just have to make sure our rewrite deduces the same facts about the domain, //: and that's something we're going to have to do anyway. //: //: To avoid the combinatorial explosion of integration tests, each layer //: mainly logs facts to the trace with a common *label*. All tests in a layer //: tend to check facts with this label. Validating the facts logged with a //: specific label is like calling functions of that layer directly. //: //: To build robust tests, trace facts about your domain rather than details of //: how you computed them. //: //: More details: http://akkartik.name/blog/tracing-tests //: //: --- //: //: Between layers and domain-driven testing, programming starts to look like a //: fundamentally different activity. Instead of focusing on a) superficial, //: b) local rules on c) code [like say http://blog.bbv.ch/2013/06/05/clean-code-cheat-sheet], //: we allow programmers to engage with the a) deep, b) global structure of //: the c) domain. If you can systematically track discontinuities in the //: domain, you don't care if the code used gotos as long as it passed all //: tests. If tests become more robust to run, it becomes easier to try out //: radically different implementations for the same program. If code is //: super-easy to rewrite, it becomes less important what indentation style it //: uses, or that the objects are appropriately encapsulated, or that the //: functions are referentially transparent. //: //: Instead of plumbing, programming becomes building and gradually refining a //: map of the environment the program must operate under. Whether a program //: is 'correct' at a given point in time is a red herring; what matters is //: avoiding regression by monotonically nailing down the more 'eventful' //: parts of the terrain. It helps readers new and old, and rewards curiosity, //: to organize large programs in self-similar hierarchies of example tests //: colocated with the code that makes them work. //: //: "Programming properly should be regarded as an activity by which //: programmers form a mental model, rather than as production of a program." //: -- Peter Naur (http://akkartik.name/naur.pdf) //:: == Core data structures :(before "End Globals") trace_stream* Trace_stream = NULL; :(before "End Types") struct trace_stream { vector<trace_line> past_lines; // End trace_stream Fields trace_stream() { // End trace_stream Constructor } ~trace_stream() { // End trace_stream Destructor } // End trace_stream Methods }; //:: == Adding to the trace //: Top-level method is trace() which can be used like an ostream. Usage: //: trace(depth, label) << ... << end(); //: Don't forget the 'end()' to actually append to the trace. :(before "End Includes") // No brackets around the expansion so that it prints nothing if Trace_stream // isn't initialized. #define trace(...) !Trace_stream ? cerr : Trace_stream->stream(__VA_ARGS__) :(before "End trace_stream Fields") // accumulator for current trace_line ostringstream* curr_stream; string curr_label; int curr_depth; // other stuff int collect_depth; // avoid tracing lower levels for speed ofstream null_stream; // never opened, so writes to it silently fail //: Some constants. :(before "struct trace_stream") // include constants in all cleaved compilation units const int Max_depth = 9999; :(before "End trace_stream Constructor") curr_stream = NULL; curr_depth = Max_depth; collect_depth = Max_depth; :(before "struct trace_stream") struct trace_line { string contents; string label; int depth; // 0 is 'sea level'; positive integers are progressively 'deeper' and lower level trace_line(string c, string l) { contents = c; label = l; depth = 0; } trace_line(string c, string l, int d) { contents = c; label = l; depth = d; } }; string unescape_newline(string& s) { std::stringstream ss; for (int i = 0; i < SIZE(s); ++i) { if (s.at(i) == '\n') ss << "\\n"; else ss << s.at(i); } return ss.str(); } void dump_trace_line(ostream& s, trace_line& t) { s << std::setw(2) << t.depth << ' ' << t.label << ": " << unescape_newline(t.contents) << '\n'; } //: Starting a new trace line. :(before "End trace_stream Methods") ostream& stream(string label) { return stream(Max_depth, label); } ostream& stream(int depth, string label) { if (depth > collect_depth) return null_stream; curr_stream = new ostringstream; curr_label = label; curr_depth = depth; (*curr_stream) << std::hex; // printing addresses is the common case return *curr_stream; } //: End of a trace line; append it to the trace. :(before "End Types") struct end {}; :(code) ostream& operator<<(ostream& os, end /*unused*/) { if (Trace_stream) Trace_stream->newline(); return os; } //: Fatal error. :(before "End Types") struct die {}; :(code) ostream& operator<<(ostream& /*unused*/, die /*unused*/) { if (Trace_stream) Trace_stream->newline(); exit(1); } :(before "End trace_stream Methods") void newline(); :(code) void trace_stream::newline() { if (!curr_stream) return; string curr_contents = curr_stream->str(); if (!curr_contents.empty()) { past_lines.push_back(trace_line(curr_contents, trim(curr_label), curr_depth)); // preserve indent in contents // maybe print this line to stderr trace_line& t = past_lines.back(); if (should_incrementally_print_trace()) { dump_trace_line(cerr, t); } // End trace Commit } // clean up delete curr_stream; curr_stream = NULL; curr_label.clear(); curr_depth = Max_depth; } //:: == Initializing the trace in tests :(before "End Includes") #define START_TRACING_UNTIL_END_OF_SCOPE lease_tracer leased_tracer; :(before "End Test Setup") START_TRACING_UNTIL_END_OF_SCOPE //: Trace_stream is a resource, lease_tracer uses RAII to manage it. :(before "End Types") struct lease_tracer { lease_tracer(); ~lease_tracer(); }; :(code) lease_tracer::lease_tracer() { Trace_stream = new trace_stream; } lease_tracer::~lease_tracer() { delete Trace_stream; Trace_stream = NULL; } //:: == Errors and warnings using traces :(before "End Includes") #define raise (!Trace_stream ? (++Trace_errors,cerr) /*do print*/ : Trace_stream->stream(Error_depth, "error")) #define warn (!Trace_stream ? (++Trace_errors,cerr) /*do print*/ : Trace_stream->stream(Warn_depth, "warn")) //: Print errors and warnings to the screen by default. :(before "struct trace_stream") // include constants in all cleaved compilation units const int Error_depth = 0; const int Warn_depth = 1; :(before "End Globals") int Hide_errors = false; // if set, don't print errors or warnings to screen int Hide_warnings = false; // if set, don't print warnings to screen :(before "End Reset") Hide_errors = false; Hide_warnings = false; //: Never dump warnings in tests :(before "End Test Setup") Hide_warnings = true; :(code) bool trace_stream::should_incrementally_print_trace() { if (!Hide_errors && curr_depth == Error_depth) return true; if (!Hide_warnings && !Hide_errors && curr_depth == Warn_depth) return true; // End Incremental Trace Print Conditions return false; } :(before "End trace_stream Methods") bool should_incrementally_print_trace(); :(before "End Globals") int Trace_errors = 0; // used only when Trace_stream is NULL // Fail tests that displayed (unexpected) errors. // Expected errors should always be hidden and silently checked for. :(before "End Test Teardown") if (Passed && !Hide_errors && trace_contains_errors()) { Passed = false; } :(code) bool trace_contains_errors() { return Trace_errors > 0 || trace_count("error") > 0; } :(before "End Includes") // If we aren't yet sure how to deal with some corner case, use assert_for_now // to indicate that it isn't an inviolable invariant. #define assert_for_now assert #define raise_for_now raise //:: == Other assertions on traces //: Primitives: //: - CHECK_TRACE_CONTENTS(lines) //: Assert that the trace contains the given lines (separated by newlines) //: in order. There can be other intervening lines between them. //: - CHECK_TRACE_DOESNT_CONTAIN(line) //: - CHECK_TRACE_DOESNT_CONTAIN(label, contents) //: Assert that the trace doesn't contain the given (single) line. //: - CHECK_TRACE_COUNT(label, count) //: Assert that the trace contains exactly 'count' lines with the given //: 'label'. //: - CHECK_TRACE_CONTAINS_ERRORS() //: - CHECK_TRACE_DOESNT_CONTAIN_ERRORS() //: - trace_count_prefix(label, prefix) //: Count the number of trace lines with the given 'label' that start with //: the given 'prefix'. :(before "End Includes") #define CHECK_TRACE_CONTENTS(...) check_trace_contents(__FUNCTION__, __FILE__, __LINE__, __VA_ARGS__) #define CHECK_TRACE_DOESNT_CONTAIN(...) CHECK(trace_doesnt_contain(__VA_ARGS__)) #define CHECK_TRACE_COUNT(label, count) \ if (Passed && trace_count(label) != (count)) { \ cerr << "\nF - " << __FUNCTION__ << "(" << __FILE__ << ":" << __LINE__ << "): trace_count of " << label << " should be " << count << '\n'; \ cerr << " got " << trace_count(label) << '\n'; /* multiple eval */ \ DUMP(label); \ Passed = false; \ return; /* Currently we stop at the very first failure. */ \ } #define CHECK_TRACE_CONTAINS_ERRORS() CHECK(trace_contains_errors()) #define CHECK_TRACE_DOESNT_CONTAIN_ERRORS() \ if (Passed && trace_contains_errors()) { \ cerr << "\nF - " << __FUNCTION__ << "(" << __FILE__ << ":" << __LINE__ << "): unexpected errors\n"; \ DUMP("error"); \ Passed = false; \ return; \ } // Allow tests to ignore trace lines generated during setup. #define CLEAR_TRACE delete Trace_stream, Trace_stream = new trace_stream :(code) bool check_trace_contents(string FUNCTION, string FILE, int LINE, string expected) { if (!Passed) return false; if (!Trace_stream) return false; vector<string> expected_lines = split(expected, "\n"); int curr_expected_line = 0; while (curr_expected_line < SIZE(expected_lines) && expected_lines.at(curr_expected_line).empty()) ++curr_expected_line; if (curr_expected_line == SIZE(expected_lines)) return true; string label, contents; split_label_contents(expected_lines.at(curr_expected_line), &label, &contents); for (vector<trace_line>::iterator p = Trace_stream->past_lines.begin(); p != Trace_stream->past_lines.end(); ++p) { if (label != p->label) continue; string t = trim(p->contents); if (contents != unescape_newline(t)) continue; ++curr_expected_line; while (curr_expected_line < SIZE(expected_lines) && expected_lines.at(curr_expected_line).empty()) ++curr_expected_line; if (curr_expected_line == SIZE(expected_lines)) return true; split_label_contents(expected_lines.at(curr_expected_line), &label, &contents); } if (line_exists_anywhere(label, contents)) { cerr << "\nF - " << FUNCTION << "(" << FILE << ":" << LINE << "): line [" << label << ": " << contents << "] out of order in trace:\n"; DUMP(""); } else { cerr << "\nF - " << FUNCTION << "(" << FILE << ":" << LINE << "): missing [" << contents << "] in trace:\n"; DUMP(label); } Passed = false; return false; } bool trace_doesnt_contain(string expected) { vector<string> tmp = split_first(expected, ": "); if (SIZE(tmp) == 1) { raise << expected << ": missing label or contents in trace line\n" << end(); assert(false); } return trace_count(tmp.at(0), tmp.at(1)) == 0; } int trace_count(string label) { return trace_count(label, ""); } int trace_count(string label, string line) { if (!Trace_stream) return 0; long result = 0; for (vector<trace_line>::iterator p = Trace_stream->past_lines.begin(); p != Trace_stream->past_lines.end(); ++p) { if (label == p->label) { if (line == "" || trim(line) == trim(p->contents)) ++result; } } return result; } int trace_count_prefix(string label, string prefix) { if (!Trace_stream) return 0; long result = 0; for (vector<trace_line>::iterator p = Trace_stream->past_lines.begin(); p != Trace_stream->past_lines.end(); ++p) { if (label == p->label) { if (starts_with(trim(p->contents), trim(prefix))) ++result; } } return result; } void split_label_contents(const string& s, string* label, string* contents) { static const string delim(": "); size_t pos = s.find(delim); if (pos == string::npos) { *label = ""; *contents = trim(s); } else { *label = trim(s.substr(0, pos)); *contents = trim(s.substr(pos+SIZE(delim))); } } bool line_exists_anywhere(const string& label, const string& contents) { for (vector<trace_line>::iterator p = Trace_stream->past_lines.begin(); p != Trace_stream->past_lines.end(); ++p) { if (label != p->label) continue; if (contents == trim(p->contents)) return true; } return false; } vector<string> split(string s, string delim) { vector<string> result; size_t begin=0, end=s.find(delim); while (true) { if (end == string::npos) { result.push_back(string(s, begin, string::npos)); break; } result.push_back(string(s, begin, end-begin)); begin = end+SIZE(delim); end = s.find(delim, begin); } return result; } vector<string> split_first(string s, string delim) { vector<string> result; size_t end=s.find(delim); result.push_back(string(s, 0, end)); if (end != string::npos) result.push_back(string(s, end+SIZE(delim), string::npos)); return result; } //:: == Helpers for debugging using traces :(before "End Includes") // To debug why a test is failing, dump its trace using '?'. #define DUMP(label) if (Trace_stream) cerr << Trace_stream->readable_contents(label); // To add temporary prints to the trace, use 'dbg'. // `git log` should never show any calls to 'dbg'. #define dbg trace(0, "a") //: Dump the entire trace to file where it can be browsed offline. //: Dump the trace as it happens; that way you get something even if the //: program crashes. :(before "End Globals") ofstream Trace_file; :(before "End Commandline Options(*arg)") else if (is_equal(*arg, "--trace")) { cerr << "saving trace to 'last_run'\n"; Trace_file.open("last_run"); // Add a dummy line up top; otherwise the `browse_trace` tool currently has // no way to expand any lines above an error. Trace_file << " 0 dummy: start\n"; // End --trace Settings } :(before "End trace Commit") if (Trace_file.is_open()) { dump_trace_line(Trace_file, t); Trace_file.flush(); past_lines.pop_back(); // economize on memory } :(before "End One-time Setup") atexit(cleanup_main); :(code) void cleanup_main() { if (Trace_file.is_open()) Trace_file.close(); // End cleanup_main } :(before "End trace_stream Methods") string readable_contents(string label) { string trim(const string& s); // prototype ostringstream output; label = trim(label); for (vector<trace_line>::iterator p = past_lines.begin(); p != past_lines.end(); ++p) if (label.empty() || label == p->label) dump_trace_line(output, *p); return output.str(); } //: Print traces to the screen as they happen. //: Particularly useful when juggling multiple trace streams, like when //: debugging sandboxes. :(before "End Globals") bool Dump_trace = false; :(before "End Commandline Options(*arg)") else if (is_equal(*arg, "--dump")) { Dump_trace = true; } :(before "End Incremental Trace Print Conditions") if (Dump_trace) return true; //: Miscellaneous helpers. :(code) string trim(const string& s) { string::const_iterator first = s.begin(); while (first != s.end() && isspace(*first)) ++first; if (first == s.end()) return ""; string::const_iterator last = --s.end(); while (last != s.begin() && isspace(*last)) --last; ++last; return string(first, last); } :(before "End Includes") #include <vector> using std::vector; #include <list> using std::list; #include <set> using std::set; #include <sstream> using std::istringstream; using std::ostringstream; #include <fstream> using std::ifstream; using std::ofstream;


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