First commit with the starter code.

.gitignore

@@ -53,3 +53,5 @@ tags
 *.out
 *.app
 
+subprojects
+builddir

Makefile

@@ -0,0 +1,18 @@
+all: build test
+
+reset:
+	powershell -executionpolicy bypass .\scripts\reset_build.ps1
+
+build:
+	meson compile -j 4 -C builddir
+
+test: build
+	./builddir/runtests
+
+install: build test
+	powershell "cp ./builddir/subprojects/libgit2-1.8.1/liblibgit2package.dll ."
+	powershell "cp ./builddir/subprojects/efsw/libefsw.dll ."
+	powershell "cp builddir/escape_turings_tarpit.exe ."
+
+clean:
+	meson compile --clean -C builddir

dbc.cpp

@@ -0,0 +1,40 @@
+#include "dbc.hpp"
+
+void dbc::log(const string &message) {
+  fmt::print("{}\n", message);
+}
+
+void dbc::sentinel(const string &message) {
+  string err = fmt::format("[SENTINEL!] {}\n", message);
+  throw dbc::SentinelError{err};
+}
+
+void dbc::pre(const string &message, bool test) {
+  if(!test) {
+    string err = fmt::format("[PRE!] {}\n", message);
+    throw dbc::PreCondError{err};
+  }
+}
+
+void dbc::pre(const string &message, std::function<bool()> tester) {
+  dbc::pre(message, tester());
+}
+
+void dbc::post(const string &message, bool test) {
+  if(!test) {
+    string err = fmt::format("[POST!] {}\n", message);
+    throw dbc::PostCondError{err};
+  }
+}
+
+void dbc::post(const string &message, std::function<bool()> tester) {
+  dbc::post(message, tester());
+}
+
+void dbc::check(bool test, const string &message) {
+  if(!test) {
+    string err = fmt::format("[CHECK!] {}\n", message);
+    fmt::println("{}", err);
+    throw dbc::CheckError{err};
+  }
+}

dbc.hpp

@@ -0,0 +1,29 @@
+#pragma once
+
+#include <string>
+#include <fmt/core.h>
+#include <functional>
+
+using std::string;
+
+namespace dbc {
+  class Error {
+    public:
+      const string message;
+      Error(string m) : message{m} {}
+      Error(const char *m) : message{m} {}
+  };
+
+  class CheckError : public Error {};
+  class SentinelError : public Error {};
+  class PreCondError : public Error {};
+  class PostCondError : public Error {};
+
+  void log(const string &message);
+  void sentinel(const string &message);
+  void pre(const string &message, bool test);
+  void pre(const string &message, std::function<bool()> tester);
+  void post(const string &message, bool test);
+  void post(const string &message, std::function<bool()> tester);
+  void check(bool test, const string &message);
+}

fsm.hpp

@@ -0,0 +1,28 @@
+#pragma once
+
+#include <fmt/core.h>
+
+#ifndef FSM_DEBUG
+#define FSM_STATE(C, S, E, ...) case C::S: S(E, ##__VA_ARGS__); break
+#else
+#define FSM_STATE(C, S, E, ...) case C::S: fmt::println(">> " #C " " #S " event={}, state={}", int(E), int(_state)); S(E, ##__VA_ARGS__); fmt::println("<< " #C " state={}", int(_state)); break
+#endif
+
+template<typename S, typename E>
+class DeadSimpleFSM {
+protected:
+  // BUG: don't put this in your class because state() won't work
+  S _state = S::START;
+
+public:
+  template<typename... Types>
+  void event(E event, Types... args);
+
+  void state(S next_state) {
+    _state = next_state;
+  }
+
+  bool in_state(S state) {
+    return _state == state;
+  }
+};

meson.build

@@ -0,0 +1,14 @@
+project('distributary', 'cpp',
+    default_options: ['cpp_std=c++20'])
+
+catch2 = dependency('catch2-with-main')
+fmt = dependency('fmt')
+
+runtests = executable('runtests', [
+  'dbc.cpp',
+  'tests/fsm.cpp',
+  'tests/dbc.cpp',
+  ],
+  dependencies: [catch2, fmt])
+
+test('tests', runtests)

scripts/reset_build.ps1

@@ -0,0 +1,11 @@
+mv .\subprojects\packagecache .
+rm -recurse -force .\subprojects\,.\builddir\
+mkdir subprojects
+mv .\packagecache .\subprojects\
+cp *.wrap subprojects
+mkdir builddir
+meson wrap install fmt
+meson wrap install catch2
+# $env:CC="clang"
+# $env:CXX="clang++"
+meson setup --default-library=static --prefer-static builddir

scripts/reset_build.sh

@@ -0,0 +1,12 @@
+#!/usr/bin/env bash
+set -e
+
+mv -f ./subprojects/packagecache .
+rm -rf subprojects builddir
+mkdir subprojects
+mv packagecache ./subprojects/
+mkdir builddir
+cp *.wrap subprojects
+meson wrap install fmt
+meson wrap install catch2
+meson setup builddir

tests/dbc.cpp

@@ -0,0 +1,39 @@
+#include <catch2/catch_test_macros.hpp>
+#include "dbc.hpp"
+
+using namespace dbc;
+
+TEST_CASE("basic feature tests", "[utils]") {
+  log("Logging a message.");
+
+  try {
+    sentinel("This shouldn't happen.");
+  } catch(SentinelError) {
+    log("Sentinel happened.");
+  }
+
+  pre("confirm positive cases work", 1 == 1);
+  pre("confirm positive lambda", [&]{ return 1 == 1;});
+  post("confirm positive post", 1 == 1);
+  post("confirm postitive post with lamdba", [&]{ return 1 == 1;});
+
+  check(1 == 1, "one equals 1");
+
+  try {
+    check(1 == 2, "this should fail");
+  } catch(CheckError err) {
+    log("check fail worked");
+  }
+
+  try {
+    pre("failing pre", 1 == 3);
+  } catch(PreCondError err) {
+    log("pre fail worked");
+  }
+
+  try {
+    post("failing post", 1 == 4);
+  } catch(PostCondError err) {
+    log("post faile worked");
+  }
+}

tests/fsm.cpp

@@ -0,0 +1,67 @@
+#include <catch2/catch_test_macros.hpp>
+#include <fmt/core.h>
+#include <string>
+#include "../fsm.hpp"
+
+using namespace fmt;
+using std::string;
+
+enum class MyState {
+  START, RUNNING, END
+};
+
+enum class MyEvent {
+  STARTED, PUSH, QUIT
+};
+
+class MyFSM : public DeadSimpleFSM<MyState, MyEvent> {
+public:
+  void event(MyEvent ev, string data="") {
+    switch(_state) {
+      FSM_STATE(MyState, START, ev);
+      FSM_STATE(MyState, RUNNING, ev, data);
+      FSM_STATE(MyState, END, ev);
+    }
+  }
+
+  void START(MyEvent ev) {
+    println("<<< START");
+    state(MyState::RUNNING);
+  }
+
+  void RUNNING(MyEvent ev, string &data) {
+    if(ev == MyEvent::QUIT) {
+      println("<<< QUITTING {}", data);
+      state(MyState::END);
+    } else {
+      println("<<< RUN: {}", data);
+      state(MyState::RUNNING);
+    }
+  }
+
+  void END(MyEvent ev) {
+    println("<<< STOP");
+    state(MyState::END);
+  }
+};
+
+TEST_CASE("confirm fsm works with optional data", "[utils]") {
+  MyFSM fsm;
+
+  REQUIRE(fsm.in_state(MyState::START));
+
+  fsm.event(MyEvent::STARTED);
+  REQUIRE(fsm.in_state(MyState::RUNNING));
+
+  fsm.event(MyEvent::PUSH);
+  REQUIRE(fsm.in_state(MyState::RUNNING));
+
+  fsm.event(MyEvent::PUSH);
+  REQUIRE(fsm.in_state(MyState::RUNNING));
+
+  fsm.event(MyEvent::PUSH);
+  REQUIRE(fsm.in_state(MyState::RUNNING));
+
+  fsm.event(MyEvent::QUIT, "DONE!");
+  REQUIRE(fsm.in_state(MyState::END));
+}