integration/luprex/core/cpp/tablecmp.cpp

#include "luastack.hpp"
#include "streambuffer.hpp"
#include "tablecmp.hpp"

// Given a table and an tnmap, return the table number of the table.
// Returns zero if the table doesn't have a table number.
//
static int get_table_number(LuaStack &MLS, LuaSlot mval, LuaSlot mtnmap) {
    lua_State *L = MLS.state();
    lua_pushvalue(L, mval.index());
    lua_rawget(L, mtnmap.index());
    int result = 0;
    if (lua_type(L, -1) == LUA_TNUMBER) {
        result = lua_tointeger(L, -1);
    }
    lua_pop(L, 1);
    return result;
}

// Get the tangible ID of a tangible.
static int64_t get_tangible_id(const LuaStack &LS, LuaSlot tab) {
    int64_t id = 0;
    if (LS.istable(tab) && LS.gettabletype(tab) == LUA_TT_TANGIBLE) {
        lua_State *L = LS.state();
        if (lua_getmetatable(L, tab.index())) {
            lua_pushstring(L, "id");
            lua_rawget(L, -2);
            if (lua_type(L, -1) == LUA_TNUMBER) {
                id = lua_tointeger(L, -1);
            }
            lua_pop(L, 2);
        }
    }
    return id;
}


static bool equivalent_values(LuaStack &MLS, LuaSlot mval, LuaSlot mtnmap,
                              LuaStack &SLS, LuaSlot sval, LuaSlot stnmap) {
    switch (MLS.xtype(mval)) {
    case LUA_TBOOLEAN: {
        if (SLS.type(sval) != LUA_TBOOLEAN) return false;
        return MLS.ckboolean(mval) == SLS.ckboolean(sval);
    }
    case LUA_TNUMBER: {
        if (SLS.type(sval) != LUA_TNUMBER) return false;
        return MLS.cknumber(mval) == SLS.cknumber(sval);
    }
    case LUA_TSTRING: {
        // This could be faster if I used lua_tolstring directly.
        if (SLS.type(sval) != LUA_TSTRING) return false;
        return MLS.ckstring(mval) == SLS.ckstring(sval);
    }
    case LUA_TFUNCTION: {
        // Cannot really compare.  Just return true if the types match.
        return SLS.type(sval) == MLS.type(mval);
    }
    case LUA_TT_GENERAL: {
        if (SLS.xtype(sval) != LUA_TT_GENERAL) return false;
        int midx = get_table_number(MLS, mval, mtnmap);
        if (midx == 0) return false;
        int sidx = get_table_number(SLS, sval, stnmap);
        if (sidx == 0) return false;
        return midx == sidx;
    }
    case LUA_TT_CLASS: {
        if (SLS.xtype(sval) != LUA_TT_CLASS) return false;
        return MLS.classname(mval) == SLS.classname(sval);
    }
    case LUA_TT_TANGIBLE: {
        if (SLS.xtype(sval) != LUA_TT_TANGIBLE) return false;
        return get_tangible_id(MLS, mval) == get_tangible_id(SLS, sval);
    }
    case LUA_TT_GLOBALENV: {
        return (SLS.xtype(sval) == LUA_TT_GLOBALENV);
    }
    default:
        // We're forcing anything else to go to NIL,
        // and once it's NIL, we consider it 'equal'.
        return SLS.type(sval) == LUA_TNIL;
    }
}

static void transmit_value(LuaStack &MLS, LuaSlot mval, LuaSlot mtnmap, StreamBuffer *sb) {
    switch (MLS.xtype(mval)) {
    case LUA_TBOOLEAN: {
        sb->write_uint8(LUA_TBOOLEAN);
        sb->write_bool(MLS.ckboolean(mval));
        return;
    }
    case LUA_TNUMBER: {
        sb->write_uint8(LUA_TNUMBER);
        sb->write_double(MLS.cknumber(mval));
        return;
    }
    case LUA_TSTRING: {
        sb->write_uint8(LUA_TSTRING);
        sb->write_string(MLS.ckstring(mval));
        return;
    }
    case LUA_TT_GENERAL: {
        sb->write_uint8(LUA_TT_GENERAL);
        sb->write_uint32(get_table_number(MLS, mval, mtnmap));
        return;
    }
    case LUA_TT_CLASS: {
        sb->write_uint8(LUA_TT_CLASS);
        sb->write_string(MLS.classname(mval));
        return;
    }
    case LUA_TT_TANGIBLE: {
        sb->write_uint8(LUA_TT_TANGIBLE);
        sb->write_int64(get_tangible_id(MLS, mval));
        return;
    }
    case LUA_TT_GLOBALENV: {
        sb->write_uint8(LUA_TT_GLOBALENV);
        return;
    }
    default:
        sb->write_uint8(LUA_TNIL);
        return;
    }
}

bool tablecmp_diff(lua_State *synch, lua_State *master, bool cmeta, StreamBuffer *sb) {
    LuaArg mtnmap, mtab, stnmap, stab;
    LuaVar skey, mkey, sval, mval, mnil;
    LuaStack SLS(synch, stnmap, stab, skey, sval);
    LuaStack MLS(master, mtnmap, mtab, mkey, mval, mnil);
    MLS.set(mnil, LuaNil);
    int nupdates = 0;

    sb->write_int32(0);
    int wc = sb->total_writes();

    MLS.set(mkey, LuaNil);
    while (MLS.next(mtab, mkey, mval)) {
        if (!MLS.issortablekey(mkey)) continue;
        MLS.movesortablekey(mkey, SLS, skey);
        SLS.rawget(sval, stab, skey);
        if (!equivalent_values(MLS, mval, mtnmap, SLS, sval, stnmap)) {
            transmit_value(MLS, mkey, mtnmap, sb);
            transmit_value(MLS, mval, mtnmap, sb);
            nupdates += 1;
        }
    }

    SLS.set(skey, LuaNil);
    while (SLS.next(stab, skey, sval)) {
        if (!SLS.issortablekey(skey)) continue;
        SLS.movesortablekey(skey, MLS, mkey);
        MLS.rawget(mval, mtab, mkey);
        if (MLS.isnil(mval)) {
            transmit_value(MLS, mkey, mtnmap, sb);
            transmit_value(MLS, mval, mtnmap, sb);
            nupdates += 1;
        }
    }

    if (cmeta) {
        SLS.getmetatable(sval, stab);
        MLS.getmetatable(mval, mtab);
        if (!equivalent_values(MLS, mval, mtnmap, SLS, sval, stnmap)) {
            transmit_value(MLS, mnil, mtnmap, sb);
            transmit_value(MLS, mval, mtnmap, sb);
            nupdates += 1;
        }
    }

    sb->overwrite_int32(wc, nupdates);

    SLS.result();
    MLS.result();
    return (nupdates > 0);
}

static void tablecmp_value_debug_string(StreamBuffer *sb, std::ostringstream &oss) {
    int kind = sb->read_uint8();
    switch (kind) {
    case LUA_TBOOLEAN: {
        bool b = sb->read_bool();
        oss << (b ? "true":"false");
        return;
    }
    case LUA_TNUMBER: {
        oss << sb->read_double();
        return;
    }
    case LUA_TSTRING: {
        oss << sb->read_string();
        return;
    }
    case LUA_TT_GENERAL: {
        oss << "table " << sb->read_int32();
        return;
    }
    case LUA_TT_CLASS: {
        oss << "class " << sb->read_string();
        return;
    }
    case LUA_TT_TANGIBLE: {
        oss << "tan " << sb->read_int64();
        return;
    }
    case LUA_TT_GLOBALENV: {
        oss << "globals";
        return;
    }
    case LUA_TNIL: {
        oss << "nil";
        return;
    }
    default:
        assert(false); // Should not get here.
    }
}

std::string tablecmp_debug_string(StreamBuffer *sb) {
    std::vector<std::string> sorted;
    std::ostringstream oss;
    int ndiffs = sb->read_int32();
    for (int i = 0; i < ndiffs; i++) {
        tablecmp_value_debug_string(sb, oss);
        oss << "=";
        tablecmp_value_debug_string(sb, oss);
        sorted.push_back(oss.str());
        oss.str("");
    }
    std::sort(sorted.begin(), sorted.end());
    for (const std::string &s : sorted) {
        oss << s << ";";
    }
    return oss.str();
}

LuaDefine(table_diffcompare, "c") {
    LuaArg mtnmap, mtab, stnmap, stab;
    LuaRet dbgstring;
    LuaVar tthread;
    LuaStack LS(L, mtnmap, mtab, stnmap, stab, dbgstring, tthread);
    // Create a temporary thread to be the 'synch model'.  We'll use the
    // existing thread as the 'master model'.
    lua_State *synch = lua_newthread(L);
    lua_replace(L, tthread.index());
    // Call tablecmp_diff.
    StreamBuffer sb;
    lua_pushvalue(L, stnmap.index());
    lua_pushvalue(L, stab.index());
    lua_xmove(L, synch, 2);
    lua_pushvalue(L, mtnmap.index());
    lua_pushvalue(L, mtab.index());
    tablecmp_diff(synch, L, true, &sb);
    // Convert the output to a debug string.
    LS.set(dbgstring, tablecmp_debug_string(&sb));
    return LS.result();
}