zeek/src/script_opt/CPP/Stmts.cc

// See the file "COPYING" in the main distribution directory for copyright.

// C++ compiler methods relating to generating code for Stmt's.

#include "zeek/script_opt/CPP/Compile.h"

namespace zeek::detail {

using namespace std;

void CPPCompile::GenStmt(const Stmt* s) {
    auto loc = s->GetLocationInfo();
    if ( loc != &detail::no_location && s->Tag() != STMT_LIST )
        Emit("// %s:%s", loc->FileName(), to_string(loc->FirstLine()));

    switch ( s->Tag() ) {
        case STMT_INIT: GenInitStmt(s->AsInitStmt()); break;

        case STMT_LIST: {
            // These always occur in contexts surrounded by {}'s,
            // so no need to add them explicitly.
            auto sl = s->AsStmtList();
            const auto& stmts = sl->Stmts();

            for ( const auto& stmt : stmts )
                GenStmt(stmt);
        } break;

        case STMT_EXPR:
            if ( auto e = s->AsExprStmt()->StmtExpr() )
                Emit("%s;", GenExpr(e, GEN_DONT_CARE, true));
            break;

        case STMT_IF: GenIfStmt(s->AsIfStmt()); break;

        case STMT_WHILE: GenWhileStmt(s->AsWhileStmt()); break;

        case STMT_NULL: Emit(";"); break;

        case STMT_RETURN: GenReturnStmt(s->AsReturnStmt()); break;

        case STMT_EVENT: GenEventStmt(static_cast<const EventStmt*>(s)); break;

        case STMT_SWITCH: GenSwitchStmt(static_cast<const SwitchStmt*>(s)); break;

        case STMT_WHEN: GenWhenStmt(static_cast<const WhenStmt*>(s)); break;

        case STMT_FOR: GenForStmt(s->AsForStmt()); break;

        case STMT_ASSERT: GenAssertStmt(s->AsAssertStmt()); break;

        case STMT_NEXT: Emit("continue;"); break;

        case STMT_BREAK:
            if ( break_level > 0 )
                Emit("break;");
            else
                Emit("return false;");
            break;

        case STMT_FALLTHROUGH: break;

        case STMT_PRINT: {
            auto el = static_cast<const ExprListStmt*>(s)->ExprList();
            Emit("do_print_stmt({%s});", GenExpr(el, GEN_VAL_PTR));
        } break;

        default: reporter->InternalError("bad statement type in CPPCompile::GenStmt");
    }
}

void CPPCompile::GenInitStmt(const InitStmt* init) {
    auto inits = init->Inits();

    for ( const auto& aggr : inits ) {
        const auto& t = aggr->GetType();

        if ( ! IsAggr(t->Tag()) )
            continue;

        auto type_name = IntrusiveVal(t);
        auto type_type = TypeType(t);
        auto type_ind = GenTypeName(t);

        if ( ! locals.contains(aggr) ) {
            // fprintf(stderr, "aggregate %s unused\n", obj_desc(aggr.get()).c_str());
            continue;
        }

        auto aggr_name = IDName(aggr);

        Emit("%s = make_intrusive<%s>(cast_intrusive<%s>(%s));", aggr_name, type_name, type_type, type_ind);

        const auto& attrs = aggr->GetAttrs();
        if ( ! attrs )
            continue;

        auto attrs_offset = AttributesOffset(attrs);
        auto attrs_str = "CPP__Attributes__[" + Fmt(attrs_offset) + "]";
        Emit("%s->SetAttrs(%s);", aggr_name, attrs_str);
    }
}

void CPPCompile::GenIfStmt(const IfStmt* i) {
    auto cond = i->StmtExpr();

    Emit("if ( %s )", GenExpr(cond, GEN_NATIVE));
    StartBlock();
    GenStmt(i->TrueBranch());
    EndBlock();

    const auto& fb = i->FalseBranch();

    if ( fb->Tag() != STMT_NULL ) {
        Emit("else");
        StartBlock();
        GenStmt(i->FalseBranch());
        EndBlock();
    }
}

void CPPCompile::GenWhileStmt(const WhileStmt* w) {
    Emit("while ( %s )", GenExpr(w->Condition(), GEN_NATIVE));

    StartBlock();

    ++break_level;
    GenStmt(w->Body());
    --break_level;

    EndBlock();
}

void CPPCompile::GenReturnStmt(const ReturnStmt* r) {
    auto e = r->StmtExpr();

    if ( in_hook )
        Emit("return true;");

    else if ( ! e && ret_type && ret_type->Tag() != TYPE_VOID )
        // This occurs for ExpressionlessReturnOkay() functions.
        Emit("return nullptr;");

    else if ( ! ret_type || ! e || e->GetType()->Tag() == TYPE_VOID )
        Emit("return;");

    else {
        auto gt = ret_type->Tag() == TYPE_ANY ? GEN_VAL_PTR : GEN_NATIVE;
        auto ret = GenExpr(e, gt);

        if ( e->GetType()->Tag() == TYPE_ANY )
            ret = GenericValPtrToGT(ret, ret_type, gt);

        Emit("return %s;", ret);
    }
}

void CPPCompile::GenEventStmt(const EventStmt* ev) {
    auto ev_s = ev->StmtExprPtr();
    auto ev_e = cast_intrusive<EventExpr>(ev_s);
    auto ev_n = ev_e->Name();

    RegisterEvent(ev_n);

    if ( ev_e->Args()->Exprs().length() > 0 )
        Emit("event_mgr.Enqueue(%s_ev, %s);", globals[string(ev_n)], GenExpr(ev_e->Args(), GEN_VAL_PTR));
    else
        Emit("event_mgr.Enqueue(%s_ev, Args{});", globals[string(ev_n)]);
}

void CPPCompile::GenSwitchStmt(const SwitchStmt* sw) {
    auto e = sw->StmtExpr();
    auto cases = sw->Cases();

    if ( sw->TypeMap()->empty() )
        GenValueSwitchStmt(e, cases);
    else
        GenTypeSwitchStmt(e, cases);
}

void CPPCompile::GenTypeSwitchStmt(const Expr* e, const case_list* cases) {
    // Start a scoping block so we avoid naming conflicts if a function
    // has multiple type switches.
    Emit("{");
    Emit("static std::vector<int> CPP__switch_types =");
    StartBlock();

    for ( const auto& c : *cases ) {
        auto tc = c->TypeCases();
        if ( tc )
            for ( const auto& id : *tc )
                Emit(Fmt(TypeOffset(id->GetType())) + ",");
    }
    EndBlock(true);

    NL();

    Emit("ValPtr CPP__sw_val = %s;", GenExpr(e, GEN_VAL_PTR));
    Emit("auto& CPP__sw_val_t = CPP__sw_val->GetType();");
    Emit("int CPP__sw_type_ind = 0;");

    Emit("for ( auto CPP__st : CPP__switch_types )");
    StartBlock();
    Emit("if ( can_cast_value_to_type(CPP__sw_val.get(), CPP__Type__[CPP__st].get()) )");
    Emit("\tbreak;");
    Emit("++CPP__sw_type_ind;");
    EndBlock();

    Emit("switch ( CPP__sw_type_ind ) {");

    ++break_level;

    int case_offset = 0;

    for ( const auto& c : *cases ) {
        auto tc = c->TypeCases();
        if ( tc ) {
            bool is_multi = tc->size() > 1;
            for ( const auto& id : *tc )
                GenTypeSwitchCase(id, case_offset++, is_multi);
        }
        else
            Emit("default:");

        StartBlock();
        GenStmt(c->Body());
        EndBlock();
    }

    --break_level;

    Emit("}"); // end the switch
    Emit("}"); // end the scoping block
}

void CPPCompile::GenTypeSwitchCase(const IDPtr id, int case_offset, bool is_multi) {
    Emit("case %s:", Fmt(case_offset));

    if ( ! id->Name() )
        // No assignment, we're done.
        return;

    // It's an assignment case.  If it's a collection of multiple cases,
    // assign to the variable only for this particular case.
    IndentUp();

    if ( is_multi ) {
        Emit("if ( CPP__sw_type_ind == %s )", Fmt(case_offset));
        IndentUp();
    }

    auto targ_val = "CPP__sw_val.get()";
    auto targ_type = string("CPP__Type__[CPP__switch_types[") + Fmt(case_offset) + "]].get()";

    auto cast = string("cast_value_to_type(") + targ_val + ", " + targ_type + ")";

    Emit("%s = %s;", LocalName(id), GenericValPtrToGT(cast, id->GetType(), GEN_NATIVE));

    IndentDown();

    if ( is_multi )
        IndentDown();
}

void CPPCompile::GenValueSwitchStmt(const Expr* e, const case_list* cases) {
    auto e_it = e->GetType()->InternalType();
    bool is_int = e_it == TYPE_INTERNAL_INT;
    bool is_uint = e_it == TYPE_INTERNAL_UNSIGNED;
    bool organic = is_int || is_uint;

    string sw_val;

    if ( organic )
        sw_val = GenExpr(e, GEN_NATIVE);
    else
        sw_val = string("p_hash(") + GenExpr(e, GEN_VAL_PTR) + ")";

    Emit("switch ( %s ) {", sw_val);

    ++break_level;

    for ( const auto& c : *cases ) {
        if ( c->ExprCases() ) {
            const auto& c_e_s = c->ExprCases()->AsListExpr()->Exprs();

            for ( const auto& c_e : c_e_s ) {
                auto c_v = c_e->Eval(nullptr);
                ASSERT(c_v);

                string c_v_rep;

                if ( is_int )
                    c_v_rep = Fmt(int(c_v->AsInt()));
                else if ( is_uint )
                    c_v_rep = Fmt(p_hash_type(c_v->AsCount()));
                else
                    c_v_rep = Fmt(p_hash(c_v));

                Emit("case %s:", c_v_rep);
            }
        }

        else
            Emit("default:");

        StartBlock();
        GenStmt(c->Body());
        EndBlock();
    }

    --break_level;

    Emit("}");
}

void CPPCompile::GenWhenStmt(const WhenStmt* w) {
    auto wi = w->Info();

    vector<string> local_aggrs;

    for ( auto& l : wi->WhenExprLocals() )
        if ( IsAggr(l->GetType()) )
            local_aggrs.push_back(IDNameStr(l));

    auto when_lambda = GenExpr(wi->Lambda(), GEN_NATIVE);
    GenWhenStmt(wi.get(), when_lambda, w->GetLocationInfo(), std::move(local_aggrs));
}

void CPPCompile::GenWhenStmt(const WhenInfo* wi, const string& when_lambda, const Location* loc,
                             vector<string> local_aggrs) {
    auto is_return = wi->IsReturn() ? "true" : "false";
    auto timeout = wi->TimeoutExpr();
    const auto& timeout_val = timeout ? GenExpr(timeout, GEN_NATIVE) : "-1.0";

    Emit("{ // begin a new scope for internal variables");

    Emit("static std::shared_ptr<WhenInfo> CPP__wi = nullptr;");
    Emit("static IDSet CPP__w_globals;");

    NL();

    Emit("if ( ! CPP__wi )");
    StartBlock();
    Emit("CPP__wi = std::make_shared<WhenInfo>(%s);", is_return);
    for ( auto& wg : wi->WhenExprGlobals() )
        Emit("CPP__w_globals.insert(find_global__CPP(\"%s\"));", wg->Name());
    EndBlock();
    NL();

    Emit("std::vector<ValPtr> CPP__local_aggrs;");
    for ( auto& la : local_aggrs )
        Emit("CPP__local_aggrs.emplace_back(%s);", la);

    Emit("CPP__wi->Instantiate(%s);", when_lambda);

    // We need a new frame for the trigger to unambiguously associate
    // with, in case we're called multiple times with our existing frame.
    Emit("auto new_frame = make_intrusive<Frame>(0, nullptr, nullptr);");
    Emit("auto curr_t = f__CPP->GetTrigger();");
    Emit("auto curr_assoc = f__CPP->GetTriggerAssoc();");
    if ( ! ret_type || ret_type->Tag() == TYPE_VOID )
        Emit("// Note, the following works even if curr_t is nil.");
    Emit("new_frame->SetTrigger({NewRef{}, curr_t});");
    Emit("new_frame->SetTriggerAssoc(curr_assoc);");

    Emit(
        "auto t = make_intrusive<trigger::Trigger>(CPP__wi, CPP__w_globals, CPP__local_aggrs, %s, "
        "new_frame.get());",
        timeout_val);

    if ( ret_type && ret_type->Tag() != TYPE_VOID ) {
        // Note, ret_type can be active but we *still* don't have
        // a return value, due to the faked-up "any" return type
        // associated with "when" lambdas, so check for that case.
        Emit("if ( curr_t )");
        StartBlock();
        Emit("ValPtr retval = {NewRef{}, curr_t->Lookup(curr_assoc)};");
        Emit("if ( ! retval )");
        Emit("\tthrow CPPDelayedCallException();");
        Emit("return %s;", GenericValPtrToGT("retval", ret_type, GEN_NATIVE));
        EndBlock();

        // Return something to avoid return-without-value warnings - but not
        // if this is a when-inside-a-when, or a hook.
        if ( ! func_type->ExpressionlessReturnOkay() && ! in_hook )
            Emit("return 0;");
    }

    Emit("}");
}

void CPPCompile::GenForStmt(const ForStmt* f) {
    Emit("{ // begin a new scope for the internal loop vars");

    ++break_level;

    auto v = f->StmtExprPtr();
    auto t = v->GetType()->Tag();
    auto loop_vars = f->LoopVars();
    auto value_var = f->ValueVar();

    if ( t == TYPE_TABLE )
        GenForOverTable(v, value_var, loop_vars);

    else if ( t == TYPE_VECTOR )
        GenForOverVector(v, value_var, loop_vars);

    else if ( t == TYPE_STRING )
        GenForOverString(v, loop_vars);

    else
        reporter->InternalError("bad for statement in CPPCompile::GenStmt");

    GenStmt(f->LoopBody());
    EndBlock();

    if ( t == TYPE_TABLE )
        EndBlock();

    --break_level;

    Emit("} // end of for scope");
}

void CPPCompile::GenForOverTable(const ExprPtr& tbl, const IDPtr& value_var, const IDPList* loop_vars) {
    Emit("auto tv__CPP = %s;", GenExpr(tbl, GEN_DONT_CARE));
    Emit("const PDict<TableEntryVal>* loop_vals__CPP = tv__CPP->AsTable();");

    Emit("if ( loop_vals__CPP->Length() > 0 )");
    StartBlock();

    Emit("for ( const auto& lve__CPP : *loop_vals__CPP )");
    StartBlock();

    Emit("auto k__CPP = lve__CPP.GetHashKey();");
    Emit("auto* current_tev__CPP = lve__CPP.value;");
    Emit("auto ind_lv__CPP = tv__CPP->RecreateIndex(*k__CPP);");

    if ( value_var && ! value_var->IsBlank() )
        Emit("%s = %s;", IDName(value_var),
             GenericValPtrToGT("current_tev__CPP->GetVal()", value_var->GetType(), GEN_NATIVE));

    int n = static_cast<int>(loop_vars->size());
    for ( int i = 0; i < n; ++i ) {
        const auto& var = (*loop_vars)[i];
        if ( var->IsBlank() )
            continue;

        const auto& v_t = var->GetType();
        auto acc = NativeAccessor(v_t);

        if ( IsNativeType(v_t) )
            Emit("%s = ind_lv__CPP->Idx(%s)%s;", IDName(var), Fmt(i), acc);
        else
            Emit("%s = {NewRef{}, ind_lv__CPP->Idx(%s)%s};", IDName(var), Fmt(i), acc);
    }
}

void CPPCompile::GenForOverVector(const ExprPtr& vec, const IDPtr& value_var, const IDPList* loop_vars) {
    Emit("auto vv__CPP = %s;", GenExpr(vec, GEN_DONT_CARE));

    Emit("for ( auto i__CPP = 0u; i__CPP < vv__CPP->Size(); ++i__CPP )");
    StartBlock();

    Emit("if ( ! vv__CPP->Has(i__CPP) ) continue;");

    const auto& lv0 = (*loop_vars)[0];

    if ( ! lv0->IsBlank() )
        Emit("%s = i__CPP;", IDName(lv0));

    if ( value_var && ! value_var->IsBlank() ) {
        auto vv = IDName(value_var);
        auto access = "vv__CPP->ValAt(i__CPP)";
        auto native = GenericValPtrToGT(access, value_var->GetType(), GEN_NATIVE);
        Emit("%s = %s;", IDName(value_var), native);
    }
}

void CPPCompile::GenForOverString(const ExprPtr& str, const IDPList* loop_vars) {
    Emit("auto sval__CPP = %s;", GenExpr(str, GEN_DONT_CARE));

    Emit("for ( auto i__CPP = 0; i__CPP < sval__CPP->Len(); ++i__CPP )");
    StartBlock();

    Emit("auto sv__CPP = make_intrusive<StringVal>(1, (const char*) sval__CPP->Bytes() + i__CPP);");

    const auto& lv0 = (*loop_vars)[0];
    if ( ! lv0->IsBlank() )
        Emit("%s = std::move(sv__CPP);", IDName(lv0));
}

void CPPCompile::GenAssertStmt(const AssertStmt* a) {
    auto cond = a->StmtExpr();
    auto& msg = a->Msg();

    Emit("{ // begin a new scope for internal \"assert\" variables");
    Emit("static auto assertion_result_hook = id::find_func(\"assertion_result\");");
    Emit(
        "bool run_result_hook = assertion_result_hook && "
        "assertion_result_hook->HasEnabledBodies();");
    Emit("auto assert_result = %s;", GenExpr(cond, GEN_NATIVE));
    Emit("if ( ! assert_result || run_result_hook )");

    StartBlock();
    if ( msg )
        Emit("auto msg_val = %s;", GenExpr(msg, GEN_VAL_PTR));
    else
        Emit("auto msg_val = zeek::val_mgr->EmptyString();");

    auto loc = a->GetLocationInfo();
    Emit("static Location loc(\"%s\", %s, %s);", loc->FileName(), to_string(loc->FirstLine()),
         to_string(loc->LastLine()));
    Emit("report_assert(assert_result, \"%s\", msg_val, &loc);", CPPEscape(a->CondDesc().c_str()).c_str());
    EndBlock();

    Emit("} // end of \"assert\" scope");
}

} // namespace zeek::detail