integration/luprex/cpp/core/source.cpp

#define _USE_MATH_DEFINES
#include <cmath>

#include "wrap-string.hpp"
#include "wrap-vector.hpp"
#include "wrap-map.hpp"
#include "wrap-set.hpp"
#include "wrap-sstream.hpp"
#include "util.hpp"
#include "luastack.hpp"
#include "traceback.hpp"
#include "table.hpp"
#include "source.hpp"
#include "luasnap.hpp"

#include <algorithm>
#include <fstream>


LuaDefine(makeclass, "classname", "create a class if it doesn't already exist") {
    LuaArg classname;
    LuaRet classtab;
    LuaDefStack LS(L, classname, classtab);
    if (!sv::is_lua_classname(LS.ckstring(classname))) {
        luaL_error(L, "invalid class name: %s", LS.ckstring(classname).c_str());
    };
    LS.makeclass(classtab, classname);
    return LS.result();
}

LuaDefine(getclass, "x", "get a class table") {
    LuaArg classname;
    LuaRet classtab;
    LuaDefStack LS(L, classname, classtab);
    eng::string err = LS.getclass(classtab, classname);
    if (err != "") {
        luaL_error(L, "%s", err.c_str());
    }
    return LS.result();
}

LuaDefine(classname, "x", "get a class name") {
    LuaArg table;
    LuaRet result;
    LuaDefStack LS(L, table, result);
    eng::string rstr = LS.classname(table);
    if (rstr == "") {
        LS.set(result, LuaNil);
    } else {
        LS.set(result, rstr);
    }
    return LS.result();
}


static std::string_view get_reg_classname(std::string_view name)
{
    size_t upos = name.find('_');
    if (upos == std::string_view::npos) {
        return "";
    } else {
        return name.substr(0, upos);
    }
}

static std::string_view get_reg_funcname(std::string_view name) {
    size_t upos = name.find('_');
    if (upos == std::string_view::npos) {
        return name;
    } else {
        return name.substr(upos + 1);
    }
}

static eng::string get_reg_fullname(std::string_view name)
{
    size_t upos = name.find('_');
    if (upos == std::string_view::npos) {
        return eng::string(name);
    } else {
        return eng::string(name.substr(0, upos)) + "." + eng::string(name.substr(upos + 1));
    }
}

static eng::string get_reg_prototype(const LuaFunctionReg *reg) {
    eng::ostringstream oss;
    oss << "function " << get_reg_fullname(reg->get_name());
    oss << "(" << reg->get_args() << ")";
    return oss.str();
}

static bool lines_contain_substring(const util::StringVec &lines, int lo, int hi, const eng::string &substring) {
    for (int i = lo; i < hi; i++) {
        if (sv::contains_substring_utf8(lines[i], substring)) {
            return true;
        }
    }
    return false;
}

static void get_info_table(LuaCoreStack &LS, LuaSlot db, LuaSlot info, const eng::string &fn) {
    LS.rawget(info, db, fn);
    if (!LS.istable(info)) {
        LS.set(info, LuaNewTable);
        LS.rawset(db, fn, info);
    }
    LS.rawset(info, "name", fn);
}

static void calculate_loadresult(LuaCoreStack &LS0, LuaSlot info, const eng::string &fn, const eng::string &code) {
    LuaVar loadresult;
    LuaExtStack LS(LS0.state(), loadresult);
    if (code == "") {
        LS.rawset(info, "loadresult", "missing or empty source file");
    } else {
        LS.load(loadresult, code, fn);
        LS.rawset(info, "loadresult", loadresult);
    }
}

void SourceDB::diff(const SourceDB &auth, StreamBuffer *sb) {
    LuaVar sdb, sfn, sinfo, shash, sseq;
    LuaVar mdb, mfn, minfo, mhash, mseq, mcode;
    LuaExtStack SLS(lua_state_, sdb, sfn, sinfo, shash, sseq);
    LuaExtStack MLS(auth.lua_state_, mdb, mfn, minfo, mhash, mseq, mcode);
    sb->write_int32(0);
    int wc_after = sb->total_writes();
    int nupdates = 0;
    // Fetch the two source databases.
    SLS.rawget(sdb, LuaRegistry, "sourcedb");
    MLS.rawget(mdb, LuaRegistry, "sourcedb");
    // Loop over the master database.
    MLS.set(mfn, LuaNil);
    while (MLS.next(mdb, mfn, minfo) != 0) {
        eng::string fn = MLS.ckstring(mfn);
        assert(MLS.istable(minfo));
        MLS.rawget(mseq, minfo, "sequence");
        MLS.rawget(mhash, minfo, "hash");
        bool diffhash = true;
        bool diffseq = true;
        SLS.set(sfn, fn);
        SLS.rawget(sinfo, sdb, sfn);
        if (SLS.istable(sinfo)) {
            SLS.rawget(shash, sinfo, "hash");
            SLS.rawget(sseq, sinfo, "sequence");
            diffhash = MLS.ckstring(mhash) != SLS.ckstring(shash);
            diffseq = MLS.ckinteger(mseq) != SLS.ckinteger(sseq);
        }
        if (diffhash || diffseq) {
            sb->write_string(MLS.ckstring(mfn));
            sb->write_int32(MLS.ckinteger(mseq));
            if (diffhash) {
                MLS.rawget(mcode, minfo, "code");
                sb->write_string(MLS.ckstring(mcode));
            } else {
                sb->write_string("\001");
            }
            nupdates += 1;
        }
    }
    // Loop over synch database.
    SLS.set(sfn, LuaNil);
    while (SLS.next(sdb, sfn, sinfo) != 0) {
        eng::string fn = SLS.ckstring(sfn);
        assert(SLS.istable(sinfo));
        MLS.set(mfn, fn);
        MLS.rawget(minfo, mdb, mfn);
        if (!MLS.istable(minfo)) {
            sb->write_string(SLS.ckstring(sfn));
            sb->write_int32(-1);
            sb->write_string("");
            nupdates += 1;
        }
    }
    sb->overwrite_int32(wc_after, nupdates);
}

bool SourceDB::patch(StreamBuffer *sb, DebugCollector *dbc) {
    lua_State *L = lua_state_;
    LuaVar db, info;
    LuaExtStack LS(L, db, info);
    LS.rawget(db, LuaRegistry, "sourcedb");
    int nupdates = sb->read_int32();
    for (int i = 0; i < nupdates; i++) {
        eng::string fn = sb->read_string();
        int sequence = sb->read_int32();
        eng::string code = sb->read_string();
        DebugLine(dbc) << "Source file " << fn << " updated";
        if (sequence < 0) {
            LS.rawset(db, fn, LuaNil);
        } else {
            get_info_table(LS, db, info, fn);
            LS.rawset(info, "sequence", sequence);
            if (code != "\001") {
                LS.rawset(info, "code", code);
                LS.rawset(info, "hash", util::hash_to_hex(util::hash_string(code)));
                calculate_loadresult(LS, info, fn, code);
            }
        }
    }
    return (nupdates > 0);
}

void SourceDB::set(const eng::string &fn, const eng::string &code, int sequence) {
    lua_State *L = lua_state_;
    LuaVar db, info;
    LuaExtStack LS(L, db, info);
    LS.rawget(db, LuaRegistry, "sourcedb");
    get_info_table(LS, db, info, fn);
    LS.rawset(info, "sequence", sequence);
    LS.rawset(info, "code", code);
    LS.rawset(info, "fingerprint", "");
    LS.rawset(info, "hash", util::hash_to_hex(util::hash_string(code)));
    calculate_loadresult(LS, info, fn, code);
}

eng::string SourceDB::get(const eng::string &fn) {
    lua_State *L = lua_state_;
    LuaVar db, info, code, sequence, loadresult;
    LuaExtStack LS(L, db, info, code, sequence, loadresult);
    LS.rawget(db, LuaRegistry, "sourcedb");
    LS.rawget(info, db, fn);
    if (!LS.istable(info)) {
        return "<nonexistent>";
    }
    LS.rawget(code, info, "code");
    LS.rawget(sequence, info, "sequence");
    LS.rawget(loadresult, info, "loadresult");
    eng::string ccode = LS.ckstring(code);
    int seqno = LS.ckint(sequence);
    eng::string cloadresult;
    if (LS.isfunction(loadresult)) {
        cloadresult = "<function>";
    } else {
        cloadresult = LS.ckstring(loadresult);
    }
    return util::ss(seqno, ":", ccode, ":", cloadresult);
}

void SourceDB::update(const util::LuaSourceVec &source) {
    lua_State *L = lua_state_;
    LuaVar sourcedb, info;
    LuaExtStack LS(L, sourcedb, info);

    // Get and clear the source database.
    LS.rawget(sourcedb, LuaRegistry, "sourcedb");
    if (!LS.istable(sourcedb)) {
        LS.newtable(sourcedb);
        LS.rawset(LuaRegistry, "sourcedb", sourcedb);
    }
    LS.cleartable(sourcedb, true);

    for (int i = 0; i < int(source.size()); i++) {
        const eng::string &file = source[i].first;
        const eng::string &code = source[i].second;
        util::dprint("Compiling ", file);
        LS.newtable(info);
        LS.rawset(info, "name", file);
        LS.rawset(info, "code", code);
        LS.rawset(info, "hash", util::hash_to_hex(util::hash_string(code)));
        LS.rawset(info, "sequence", i + 1);
        calculate_loadresult(LS, info, file, code);
        LS.rawset(sourcedb, file, info);
    }
}

// Delete everything from the global environment.
// Clear all the classes in the registry classes table.
//
static void source_clear_globals(lua_State *L) {
    LuaVar classname, classtab, key, globtab, classes;
    LuaExtStack LS(L, classname, classtab, key, globtab, classes);

    LS.getglobaltable(globtab);
    LS.cleartable(globtab, true);
    LS.rawset(globtab, "_G", globtab);

    LS.rawget(classes, LuaRegistry, "classes");
    assert(LS.istable(classes));
    LS.set(classname, LuaNil);
    while (LS.next(classes, classname, classtab) != 0) {
        assert(LS.istable(classtab));
        LS.cleartable(classtab, true);
    }
}


// Load all the 'LuaDefine' C functions into the lua state.
//
static void source_load_cfunctions(lua_State *L) {
    LuaVar classobj;
    LuaExtStack LS(L, classobj);
    for (auto r = LuaFunctionReg::All; r != nullptr; r=r->next()) {
        lua_CFunction func = r->get_func();
        if ((func != nullptr) && (!r->get_sandbox())) {
            std::string_view classname = get_reg_classname(r->get_name());
            std::string_view funcname = get_reg_funcname(r->get_name());
            if (classname.empty()) {
                LS.getglobaltable(classobj);
                LS.rawset(classobj, funcname, func);
            } else {
                LS.makeclass(classobj, classname);
                LS.rawset(classobj, funcname, func);
            }
        }
    }
}

// Load all the 'LuaConstant' constants into the lua state.
//
static void source_load_cconstants(lua_State *L) {
    LuaVar classobj, value;
    LuaExtStack LS(L, classobj, value);
    for (auto r = LuaConstantReg::All; r != nullptr; r=r->next()) {
        if (r->get_tokenvalue().empty()) {
            LS.set(value, r->get_numbervalue());
        } else {
            LS.set(value, r->get_tokenvalue());
        }
        std::string_view classname = get_reg_classname(r->get_name());
        std::string_view funcname = get_reg_funcname(r->get_name());
        if (classname.empty()) {
            LS.getglobaltable(classobj);
            LS.rawset(classobj, funcname, value);
        } else {
            LS.makeclass(classobj, classname);
            LS.rawset(classobj, funcname, value);
        }
    }
}

eng::string SourceDB::get_source(const eng::string &fn)
{
    LuaVar sourcedb, fname, finfo, code;
    LuaExtStack LS(lua_state_, sourcedb, fname, finfo, code);

    // Get the source database.
    LS.rawget(sourcedb, LuaRegistry, "sourcedb");
    if (!LS.istable(sourcedb)) return "";

    // Get the finfo table from the source db.
    LS.set(fname, fn);
    LS.rawget(finfo, sourcedb, fname);
    if (!LS.istable(finfo)) return "";

    // Get the code from the finfo table.
    LS.rawget(code, finfo, "code");
    if (!LS.isstring(code)) return "";
    
    return LS.ckstring(code);
}


eng::vector<eng::string> SourceDB::modules() {
    eng::vector<eng::string> result;
    LuaVar sourcedb, key, info, seq;
    LuaExtStack LS(lua_state_, sourcedb, key, info, seq);

    result.push_back("CORE");

    // Get the source database.
    LS.rawget(sourcedb, LuaRegistry, "sourcedb");
    if (!LS.istable(sourcedb)) {
        return result;
    }

    // Sort the keys by sequence number.
    eng::map<int, eng::string> indices;
    LS.set(key, LuaNil);
    while (LS.next(sourcedb, key, info) != 0) {
        LS.rawget(seq, info, "sequence");
        indices[LS.ckinteger(seq)] = LS.ckstring(key);
    }

    for (const auto &pair : indices) {
        result.push_back(pair.second);
    }
    return result;
}

void SourceDB::rebuild_core() {
    source_clear_globals(lua_state_);
    source_load_cfunctions(lua_state_);
    source_load_cconstants(lua_state_);
}   

eng::string SourceDB::rebuild_module(const eng::string &mod) {
    if (mod == "CORE") {
        rebuild_core();
        return "";
    } else {
        LuaVar sourcedb, info, closure;
        LuaExtStack LS(lua_state_, sourcedb, info, closure);
        LS.rawget(sourcedb, LuaRegistry, "sourcedb");
        if (!LS.istable(sourcedb)) {
            return "SourceDB not initialized";
        }
        LS.rawget(info, sourcedb, mod);
        if (!LS.istable(info)) {
            return util::ss("No such module: ", mod);
        }
        LS.rawget(closure, info, "loadresult");
        if (!LS.isfunction(closure)) {
            return util::ss(mod, ":", LS.ckstring(closure));
        }
        lua_pushvalue(lua_state_, closure.index());
        return traceback_pcall(lua_state_, 0, 0);
    }
}

void SourceDB::run_unittests() {
    lua_State *L = lua_state_;
    LuaVar unittests, name, func, err, globtab;
    LuaExtStack LS(L, unittests, name, func, err, globtab);

    LS.getglobaltable(globtab);
    LS.rawget(unittests, globtab, "unittests");

    // Sort the unit test names.
    eng::set<eng::string> names;
    LS.set(name, LuaNil);
    while (LS.next(unittests, name, func) != 0) {
        if (LS.isfunction(func) && LS.isstring(name)) {
            names.insert(LS.ckstring(name));
        }
    }

    // Run the functions in order
    bool any = false;
    for (const eng::string &name : names) {
        util::dprint("Running unittests: ", name);
        LS.rawget(func, unittests, name);

        lua_pushvalue(L, func.index());
        eng::string msg = traceback_pcall(L, 0, 0);
        if (!msg.empty()) {
            LS.set(err, msg);
            util::dprint(msg);
            any = true;
        }
    }

    if (any) {
        exit(1);
    }
}

void SourceDB::init(lua_State *L) {
    lua_state_ = L;
    LuaVar globtab, persist, unpersist, classname, classtab, funcname, funcp, rawfunc, nullstring;
    LuaExtStack LS(L, globtab, persist, unpersist, classname, classtab, funcname, funcp, rawfunc, nullstring);
    LS.getglobaltable(globtab);
    LS.rawset(LuaRegistry, "sourcedb", LuaNewTable);

    // Set the metatable for strings.
    LS.makeclass(classtab, "string");
    LS.set(nullstring, "");
    LS.setmetatable(nullstring, classtab);

    // Rebuild the global environment.
    rebuild_core();
    
    // We need to register all C functions with the eris permanents tables.
    LS.rawget(persist, LuaRegistry, "persist");
    LS.rawget(unpersist, LuaRegistry, "unpersist");
    LS.set(classname, LuaNil);
    while (LS.next(globtab, classname, classtab) != 0) {
        if (LS.isstring(classname) && LS.istable(classtab)) {
            LS.set(funcname, LuaNil);
            while (LS.next(classtab, funcname, funcp) != 0) {
                if (LS.isstring(funcname) && LS.iscfunction(funcp)) {
                    eng::string full = "cfunc:";
                    full += LS.ckstring(classname);
                    full += ".";
                    full += LS.ckstring(funcname);
                    lua_pushcfunction(L, lua_tocfunction(L, funcp.index()));
                    lua_replace(L, rawfunc.index());
                    LS.rawset(persist, rawfunc, full);
                    LS.rawset(unpersist, full, rawfunc);
                }
            }
        }
    }
}

void SourceDB::serialize_source(const util::LuaSourceVec &sv, StreamBuffer *sb) {
    sb->write_int32(sv.size());
    for (const auto &pair : sv) {
        sb->write_string(pair.first);
        sb->write_string(pair.second);
    }
}

void SourceDB::deserialize_source(util::LuaSourceVec *sv, StreamBuffer *sb) {
    sv->clear();
    int count = sb->read_int32();
    if ((count < 0) || (count > 10000)) throw StreamCorruption();
    for (int i = 0; i < count; i++) {
        eng::string fn = sb->read_string();
        eng::string code = sb->read_string();
        sv->emplace_back(fn, code);
    }
}

// Register lua builtins.
//
// To find the lua builtins, we use this approach: we create a new lua state
// (the 'prototype', we call it), and we call luaL_openlibs on it.  The
// prototype should now contain all the builtins.
//
// Then, we iterate over our function registry, looking for LuaDefineBuiltin
// records.  These records don't have a function pointer yet.  For each such
// record, we look into the prototype, and look up the function in the global
// environment.  If it's not found, we print an error. If we find it, we extract
// the C function pointer from it.  Then, we remove the function from the
// prototype, to indicate that we already processed that function.
//
// At the end, we scan the prototype to make sure all functions have been
// removed. If not, we know our function registry is missing something and we
// print out an error.
//
void SourceDB::register_lua_builtins() {
    lua_State *L = LuaCoreStack::newstate(nullptr);
    luaL_openlibs(L);
    {
        LuaVar globals, lclassname, lfuncname, classtab, func;
        LuaExtStack LS(L, globals, lclassname, lfuncname, classtab, func);
        LS.getglobaltable(globals);

        // Iterate over the function registry, copying function pointers from
        // the prototype lua state into the registry, then remove the closure
        // from the prototype.
        for (auto reg = LuaFunctionReg::All; reg != nullptr; reg=reg->next()) {
            std::string_view classname = get_reg_classname(reg->get_name());
            std::string_view funcname = get_reg_funcname(reg->get_name());
            if (classname.empty()) {
                LS.getglobaltable(classtab);
            } else {
                LS.rawget(classtab, globals, classname);
            }
            lua_CFunction builtin = nullptr;
            if (LS.istable(classtab)) {
                LS.rawget(func, classtab, funcname);
                if (LS.iscfunction(func)) {
                    builtin = lua_tocfunction(L, func.index());
                    LS.rawset(classtab, funcname, LuaNil);
                }
            }
            if (reg->get_func() == nullptr) {
                if (builtin == nullptr) {
                    if (!reg->get_sandbox()) {
                        util::dprint("No such builtin function: ", classname, " ", funcname);
                    }
                } else {
                    reg->set_func(builtin);
                }
            }
        }

        // Iterate over the prototype.  All cfunctions should have been removed.
        LS.set(lclassname, LuaNil);
        while (LS.next(globals, lclassname, classtab)) {
            if (LS.isstring(lclassname)) {
                if (LS.istable(classtab)) {
                    LS.set(lfuncname, LuaNil);
                    while (LS.next(classtab, lfuncname, func)) {
                        if (LS.iscfunction(func)) {
                            util::dprint("Failed to declare builtin: ", LS.ckstring(lclassname), ".", LS.ckstring(lfuncname));
                        }
                    }
                }
            }
        }
    }
    lua_close(L);
}

bool SourceDB::search_docs(const eng::string &substring, std::ostream &ostream) {
    eng::map<eng::string, eng::string> results;

    // Search the built-in functions.
    for (const LuaFunctionReg *reg = LuaFunctionReg::All; reg != nullptr; reg=reg->next()) {
        eng::string proto = get_reg_prototype(reg);
        if (reg->get_sandbox()) continue;
        if (sv::has_prefix(reg->get_name(), "unittests_")) continue;
        if (sv::contains_substring_utf8(proto, substring) ||
            sv::contains_substring_utf8(reg->get_docs(), substring)) {
            std::ostringstream oss;
            oss << proto;
            util::StringVec docs = util::split_docstring(reg->get_docs());
            for (const eng::string &line : docs) {
                if (sv::contains_substring_utf8(line, substring)) {
                    oss << " -- " << sv::trim(line);
                    break;
                }
            }
            oss << std::endl;
            results[get_reg_fullname(reg->get_name())] = oss.str();
        }
    }

    // Search the lua source code.
    for (const eng::string &module : modules()) {
        if (module == "CORE") continue;
        eng::string code = get_source(module);
        if (code.empty()) continue;
        util::StringVec lines = util::split_lines(code);
        int comment_lines = 0;
        for (int i = 0; i < int(lines.size()); i++) {
            std::string_view fullname = sv::lua_function_proto_name(lines[i]);
            if (sv::has_prefix(fullname, "unittests.")) continue;
            if (!fullname.empty()) {
                if (lines_contain_substring(lines, i - comment_lines, i+1, substring)) {
                    eng::ostringstream oss;
                    oss << lines[i];
                    for (int j = i - comment_lines; j < i; j++) {
                        if (sv::contains_substring_utf8(lines[j], substring)) {
                            oss << " " << sv::trim(lines[j]);
                            break;
                        }
                    }
                    oss << std::endl;
                    results[eng::string(fullname)] = oss.str();
                }
                comment_lines = 0;
            } else if (sv::is_lua_comment(lines[i])) {
                comment_lines++;
            } else {
                comment_lines = 0;
            }
        }
    }

    for (const auto &pair : results) {
        ostream << pair.second;
    }
    return !results.empty();
}

bool SourceDB::function_docs(const LuaCoreStack &LS, LuaSlot fn, std::ostream &ostream) {
    lua_State *L = LS.state();
    if (LS.iscfunction(fn)) {
        lua_CFunction cfn = lua_tocfunction(L, fn.index());
        const LuaFunctionReg *reg = LuaFunctionReg::lookup(cfn);
        if (reg == nullptr) return false;
        ostream << get_reg_prototype(reg) << std::endl;
        util::StringVec docs = util::split_docstring(reg->get_docs());
        ostream << "--" << std::endl;
        for (const eng::string &line : docs) {
            ostream << "-- " << line << std::endl;
        }
        ostream << "--" << std::endl;
        return true;
    } else if (LS.isfunction(fn)) {
        lua_Debug ar;
        lua_pushvalue(L, fn.index());
        int status = lua_getinfo(L, ">S", &ar);
        if (status == 0) return false;

        // Get the source code.
        util::StringVec lines = util::split_lines(get_source(eng::string(ar.short_src)));
        if (lines.empty()) return false;
        
        // Find the line of code containing the function prototype.
        // Lua numbers source lines from 1, but we number lines from 0,
        // so we have to subtract one.
        int linehi = ar.linedefined - 1;
        if ((linehi < 0) || (linehi >= int(lines.size()))) {
            return false;
        }

        // Incorporate the function comment.
        int linelo = linehi;
        while ((linelo > 0) && (sv::is_lua_comment(lines[linelo-1]))) linelo -= 1;
        
        // Output the docs.
        ostream << lines[linehi] << std::endl;
        ostream << "--" << std::endl;
        for (int i = linelo; i < linehi; i++) {
            ostream << lines[i] << std::endl;
        }
        ostream << "--" << std::endl;
        return true;
    } else {
        return false;
    }
}

// These should go away eventually.  They're for debugging.
LuaDefine(coroutine_setnextid, "thread,id", "set the next id of a thread (debugging only)") {
    LuaArg co, lid;
    LuaDefStack LS(L, co, lid);
    lua_State *CO = LS.ckthread(co);
    lua_Number id = LS.ckinteger(lid);
    lua_setnextid(CO, id);
    return LS.result();
}

LuaDefine(coroutine_getnextid, "thread", "get the next id of a thread (debugging only)") {
    LuaArg co;
    LuaRet lid;
    LuaDefStack LS(L, co, lid);
    lua_State *CO = LS.ckthread(co);
    LS.set(lid, lua_getnextid(CO));
    return LS.result();
}

LuaDefine(unittests_sourcedb, "", "some unit tests") {
    LuaSnap msnap;
    LuaSnap ssnap;
    SourceDB mdb;
    SourceDB sdb;
    mdb.init(msnap.state());
    sdb.init(ssnap.state());
    StreamBuffer sb;

    // Create a code database using 'set'.
    mdb.set("foo", "function foo() print('foo') end", 1);
    mdb.set("bar", "function bar() print('bar') end", 2);
    mdb.set("zoo", "funcjdshja mxooso yowza!", 3);
    
    // Verify that get works.
    LuaAssertStrEq(L, mdb.get("foo"), "1:function foo() print('foo') end:<function>");
    LuaAssertStrEq(L, mdb.get("bar"), "2:function bar() print('bar') end:<function>");
    LuaAssertStrEq(L, mdb.get("zoo"), "3:funcjdshja mxooso yowza!:zoo:1: syntax error near 'mxooso'");
    LuaAssertStrEq(L, mdb.get("baz"), "<nonexistent>");

    // Difference transmit.
    sdb.diff(mdb, &sb);

    // There should still be nothing in the sdb.
    LuaAssertStrEq(L, sdb.get("foo"), "<nonexistent>");
    LuaAssertStrEq(L, sdb.get("bar"), "<nonexistent>");
    LuaAssertStrEq(L, sdb.get("zoo"), "<nonexistent>");
    LuaAssertStrEq(L, sdb.get("baz"), "<nonexistent>");

    // Apply the diffs.
    sdb.patch(&sb, nullptr);

    // Everything should now be copied to sdb.
    LuaAssertStrEq(L, sdb.get("foo"), "1:function foo() print('foo') end:<function>");
    LuaAssertStrEq(L, sdb.get("bar"), "2:function bar() print('bar') end:<function>");
    LuaAssertStrEq(L, sdb.get("zoo"), "3:funcjdshja mxooso yowza!:zoo:1: syntax error near 'mxooso'");
    LuaAssertStrEq(L, sdb.get("baz"), "<nonexistent>");

    // Make a single change to the code.
    mdb.set("bar", "function bar1() print('bar1') end", 2);

    // Diff and patch
    sdb.diff(mdb, &sb);
    sdb.patch(&sb, nullptr);

    // Verify that it's been updated.
    LuaAssertStrEq(L, sdb.get("foo"), "1:function foo() print('foo') end:<function>");
    LuaAssertStrEq(L, sdb.get("bar"), "2:function bar1() print('bar1') end:<function>");
    LuaAssertStrEq(L, sdb.get("zoo"), "3:funcjdshja mxooso yowza!:zoo:1: syntax error near 'mxooso'");
    LuaAssertStrEq(L, sdb.get("baz"), "<nonexistent>");

    // Make a single change to just a sequence number.
    mdb.set("foo", "function foo() print('foo') end", 6);

    // Diff
    sdb.diff(mdb, &sb);

    // The only thing we've updated is a single sequence number.  Make
    // sure the number of bytes transmitted is reasonable.
    //    4 bytes for the count of changes
    //    4 bytes for "foo"
    //    4 bytes for the sequence number
    //    2 bytes for unmodified code
    // This verifies that the hash comparisons are working.
    LuaAssert(L, sb.fill() == 14);

    // Patch.
    sdb.patch(&sb, nullptr);

    // Verify that it's been updated.
    LuaAssertStrEq(L, sdb.get("foo"), "6:function foo() print('foo') end:<function>");
    LuaAssertStrEq(L, sdb.get("bar"), "2:function bar1() print('bar1') end:<function>");
    LuaAssertStrEq(L, sdb.get("zoo"), "3:funcjdshja mxooso yowza!:zoo:1: syntax error near 'mxooso'");
    LuaAssertStrEq(L, sdb.get("baz"), "<nonexistent>");

    return 0;
}

LuaDefineBuiltin(table_concat, "vector1, vector2", "concatenate two vectors");
LuaDefineBuiltin(table_insert, "vector, pos, value", "insert an element into a vector");
LuaDefineBuiltin(table_remove, "vector, pos", "remove an element from a vector");
LuaDefineBuiltin(table_sort, "vector [,comparefn]", "sort a vector");
LuaDefineBuiltin(table_pack, "v1, v2, v3...", "turn a sequence of arguments into a vector");
LuaDefineBuiltin(table_unpack, "vector", "turn a vector into a sequence of return values");
LuaSandboxBuiltin(table_maxn, "", "");

LuaDefineBuiltin(string_byte, "str [,index]", "get a single byte from a string");
LuaDefineBuiltin(string_char, "byte, byte,...", "convert sequence of bytes to a string");
LuaDefineBuiltin(string_find, "str, pattern [,index]", "return start and end of pattern in a string");
LuaDefineBuiltin(string_len, "str", "return the length of the string, in bytes");
LuaDefineBuiltin(string_rep, "str, count", "repeat the string some number of times");
LuaDefineBuiltin(string_reverse, "str", "reverse the bytes of the string");
LuaDefineBuiltin(string_lower, "str", "convert string to lowercase");
LuaDefineBuiltin(string_upper, "str", "convert string to uppercase");
LuaDefineBuiltin(string_gmatch, "str, pattern", "iterate over pattern-matched substrings");
LuaDefineBuiltin(string_gsub, "str, pattern, replace", "global replace pattern in string");
LuaDefineBuiltin(string_match, "str, pattern", "return start and end of pattern in string");
LuaDefineBuiltin(string_sub, "str, pos1, pos2", "return substring of str from pos1 to pos2");
LuaSandboxBuiltin(string_dump, "func", "convert a function to a string");

LuaDefineBuiltin(bit32_arshift, "n, shift", "shift 32-bit number to the right, keeping high bit unchanged");
LuaDefineBuiltin(bit32_band, "n, n, n...", "return the bitwise and of all 32-bit numbers");
LuaDefineBuiltin(bit32_bnot, "n", "return the bitwise negation of n, ie, (-1 - n) % 2^32");
LuaDefineBuiltin(bit32_bor, "n, n, n...", "return the bitwise or of all 32-bit arguments");
LuaDefineBuiltin(bit32_bxor, "n, n, n...", "return the bitwise exclusive or of all 32-bit arguments");
LuaDefineBuiltin(bit32_btest, "n, n, n...", "compute bitwise and of all 32-bit arguments, return true if nonzero");
LuaDefineBuiltin(bit32_extract, "n, field, width", "return value from extracted bitfield of 32-bit number");
LuaDefineBuiltin(bit32_lrotate, "n, shift", "rotate 32-bit number to the left");
LuaDefineBuiltin(bit32_lshift, "n, shift", "shift 32-bit number to the left, padding with zeros");
LuaDefineBuiltin(bit32_replace, "n, v, field, width", "change value of extracted bitfield in 32-bit number");
LuaDefineBuiltin(bit32_rrotate, "n, shift", "rotate 32-bit number to the right");
LuaDefineBuiltin(bit32_rshift, "n, shift", "shift 32-bit number to the right, padding with zeros");

LuaDefineBuiltin(math_abs, "x", "return absolute value of x");
LuaDefineBuiltin(math_acos, "x", "return arc-cosine of x in radians");
LuaDefineBuiltin(math_asin, "x", "return arc-sine of x in radians");
LuaDefineBuiltin(math_atan, "x", "return the arc-tangent of x in radians");
LuaDefineBuiltin(math_atan2, "y, x", "return arc-tangent of y/x, using signs to compute quadrant");
LuaDefineBuiltin(math_ceil, "x", "return the smallest integer larger than or equal to x");
LuaDefineBuiltin(math_cos, "x", "return the cosine of x in radians");
LuaDefineBuiltin(math_cosh, "x", "return the hyperbolic cosine of x in radians");
LuaDefineBuiltin(math_deg, "rad", "convert radians to degrees");
LuaDefineBuiltin(math_exp, "x", "returns the value e^x");
LuaDefineBuiltin(math_floor, "x", "returns the smallest integer less than or equal to x");
LuaDefineBuiltin(math_fmod, "x, y", "return the remainder of x/y that rounds the quotient towards zero");
LuaDefineBuiltin(math_frexp, "x", "given x, returns mantissa and exponent");
LuaDefineBuiltin(math_ldexp, "x", "return unnormalized mantissa and exponent");
LuaDefineBuiltin(math_log, "x [, base]", "return the log of x in base, default base is e");
LuaDefineBuiltin(math_max, "x, x, x...", "return the largest argument");
LuaDefineBuiltin(math_min, "x, x, x...", "return the smallest argument");
LuaDefineBuiltin(math_modf, "x", "returns the integral and fractional part of x");
LuaDefineBuiltin(math_pow, "x, y", "returns x ^ y, equivalent to the operator");
LuaDefineBuiltin(math_rad, "deg", "convert degrees to radians");
LuaDefineBuiltin(math_sin, "x", "return the sine of x in radians");
LuaDefineBuiltin(math_sinh, "x", "return the hyperbolic sine of x in radians");
LuaDefineBuiltin(math_sqrt, "x", "return the square root of x");
LuaDefineBuiltin(math_tan, "x", "return the tangent of x in radians");
LuaDefineBuiltin(math_tanh, "x", "return the hyperbolic tangent of x in radians");
LuaSandboxBuiltin(math_log10, "", "");
LuaNumberConstant(math_pi, M_PI, "");
LuaNumberConstant(math_huge, HUGE_VAL, "");
LuaNumberConstant(math_nan, NAN, "");
LuaNumberConstant(math_maxint, LuaCoreStack::MAXINT, "");
LuaTokenConstant(math_auto, "auto", "A value used to request that a value should be automatically computed");

// math.random and math.randomseed are in world-accessor.cpp, because
// generating random numbers must manipulate global state which is
// stored in the world model.

LuaDefineBuiltin(assert, "flag [,message]", "assert that flag is true, if not, raise error");
LuaDefineBuiltin(error, "message", "raise an error");
LuaDefineBuiltin(getmetatable, "table", "get the metatable of a table");
LuaDefineBuiltin(ipairs, "vector", "meant to be used in loops, iterates over a vector");
LuaDefineBuiltin(next, "table, k", "returns the key after k and the corresponding value");
LuaDefineBuiltin(pairs, "table", "meant to be used in loops, iterates over a table");
LuaDefineBuiltin(rawpairs, "table", "meant to be used in loops, iterates over a table");
LuaDefineBuiltin(pcall, "function, arg1, arg2, ...", "call the function, catching any errors");
LuaDefineBuiltin(rawequal, "val1, val2", "return true if the two values are the same object");
LuaDefineBuiltin(rawlen, "obj", "return the length of a vector or string");
LuaDefineBuiltin(rawget, "table, key", "get a table entry, ignoring metamethods");
LuaDefineBuiltin(rawset, "table, key, value", "set a table entry, ignoring metamethods");
LuaDefineBuiltin(select, "n, arg1, arg2, ...", "return the nth argument");
LuaDefineBuiltin(setmetatable, "table, meta", "set the metatable of the specified table");
LuaDefineBuiltin(tonumber, "str", "convert a string to a number");
LuaDefineBuiltin(type, "obj", "return the type of obj as a string");
// print is redefined in world.cpp (because it prints into the world model)
// tostring is redefined in pprint.cpp

LuaSandboxBuiltin(collectgarbage, "", "");
LuaSandboxBuiltin(dofile, "", "");
LuaSandboxBuiltin(xpcall, "", "");
LuaSandboxBuiltin(loadfile, "", "");
LuaSandboxBuiltin(load, "", "");
LuaSandboxBuiltin(require, "", "");
LuaSandboxBuiltin(module, "", "");
LuaSandboxBuiltin(loadstring, "", "");
LuaSandboxBuiltin(unpack, "", "");


LuaSandboxBuiltin(debug_debug, "", "");
LuaSandboxBuiltin(debug_getuservalue, "", "");
LuaSandboxBuiltin(debug_gethook, "", "");
LuaSandboxBuiltin(debug_getinfo, "", "");
LuaSandboxBuiltin(debug_getlocal, "", "");
LuaSandboxBuiltin(debug_getregistry, "", "");
LuaSandboxBuiltin(debug_getmetatable, "", "");
LuaSandboxBuiltin(debug_getupvalue, "", "");
LuaSandboxBuiltin(debug_upvaluejoin, "", "");
LuaSandboxBuiltin(debug_upvalueid, "", "");
LuaSandboxBuiltin(debug_setuservalue, "", "");
LuaSandboxBuiltin(debug_sethook, "", "");
LuaSandboxBuiltin(debug_setlocal, "", "");
LuaSandboxBuiltin(debug_setmetatable, "", "");
LuaSandboxBuiltin(debug_setupvalue, "", "");
LuaSandboxBuiltin(debug_traceback, "", "");

LuaSandboxBuiltin(eris_persist, "", "");
LuaSandboxBuiltin(eris_unpersist, "", "");
LuaSandboxBuiltin(eris_settings, "", "");

LuaSandboxBuiltin(package_loadlib, "", "");
LuaSandboxBuiltin(package_searchpath, "", "");
LuaSandboxBuiltin(package_seeall, "", "");

LuaSandboxBuiltin(coroutine_create, "", "");
LuaSandboxBuiltin(coroutine_resume, "", "");
LuaSandboxBuiltin(coroutine_running, "", "");
LuaSandboxBuiltin(coroutine_status, "", "");
LuaSandboxBuiltin(coroutine_wrap, "", "");
LuaSandboxBuiltin(coroutine_yield, "", "");

LuaSandboxBuiltin(io_close, "", "");
LuaSandboxBuiltin(io_flush, "", "");
LuaSandboxBuiltin(io_input, "", "");
LuaSandboxBuiltin(io_lines, "", "");
LuaSandboxBuiltin(io_open, "", "");
LuaSandboxBuiltin(io_output, "", "");
LuaSandboxBuiltin(io_popen, "", "");
LuaSandboxBuiltin(io_read, "", "");
LuaSandboxBuiltin(io_tmpfile, "", "");
LuaSandboxBuiltin(io_type, "", "");
LuaSandboxBuiltin(io_write, "", "");

LuaSandboxBuiltin(os_clock, "", "");
LuaSandboxBuiltin(os_date, "", "");
LuaSandboxBuiltin(os_difftime, "", "");
LuaSandboxBuiltin(os_execute, "", "");
LuaSandboxBuiltin(os_exit, "", "");
LuaSandboxBuiltin(os_getenv, "", "");
LuaSandboxBuiltin(os_remove, "", "");
LuaSandboxBuiltin(os_rename, "", "");
LuaSandboxBuiltin(os_setlocale, "", "");
LuaSandboxBuiltin(os_time, "", "");
LuaSandboxBuiltin(os_tmpname, "", "");