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

#include "Gen-ZAM.h"

#include <cctype>
#include <cstring>
#include <map>
#include <regex>
#include <set>

using namespace std;

// Helper functions to convert dashes to underscores or vice versa.
static char dash_to_under(char c) { return c == '-' ? '_' : c; }

static char under_to_dash(char c) { return c == '_' ? '-' : c; }

// Structure for binding together Zeek script types, internal names Gen-ZAM
// uses to track them, mnemonics for referring to them in instruction names,
// the corresponding Val accessor, and whether the type requires memory
// management.
struct TypeInfo {
    string tag;
    ZAM_Type zt;
    string suffix;
    string accessor; // doesn't include "As" prefix or "()" suffix
    bool is_managed;
};

static vector<TypeInfo> ZAM_type_info = {
    {"TYPE_ADDR", ZAM_TYPE_ADDR, "A", "Addr", true},       {"TYPE_ANY", ZAM_TYPE_ANY, "a", "Any", true},
    {"TYPE_COUNT", ZAM_TYPE_UINT, "U", "Count", false},    {"TYPE_DOUBLE", ZAM_TYPE_DOUBLE, "D", "Double", false},
    {"TYPE_FILE", ZAM_TYPE_FILE, "f", "File", true},       {"TYPE_FUNC", ZAM_TYPE_FUNC, "F", "Func", true},
    {"TYPE_INT", ZAM_TYPE_INT, "I", "Int", false},         {"TYPE_LIST", ZAM_TYPE_LIST, "L", "List", true},
    {"TYPE_OPAQUE", ZAM_TYPE_OPAQUE, "O", "Opaque", true}, {"TYPE_PATTERN", ZAM_TYPE_PATTERN, "P", "Pattern", true},
    {"TYPE_RECORD", ZAM_TYPE_RECORD, "R", "Record", true}, {"TYPE_STRING", ZAM_TYPE_STRING, "S", "String", true},
    {"TYPE_SUBNET", ZAM_TYPE_SUBNET, "N", "SubNet", true}, {"TYPE_TABLE", ZAM_TYPE_TABLE, "T", "Table", true},
    {"TYPE_TYPE", ZAM_TYPE_TYPE, "t", "Type", true},       {"TYPE_VECTOR", ZAM_TYPE_VECTOR, "V", "Vector", true},
};

// Maps op-type mnemonics to the corresponding internal value used by Gen-ZAM.
static unordered_map<char, ZAM_Type> type_names = {
    {'*', ZAM_TYPE_DEFAULT}, {'A', ZAM_TYPE_ADDR},   {'a', ZAM_TYPE_ANY},     {'D', ZAM_TYPE_DOUBLE},
    {'f', ZAM_TYPE_FILE},    {'F', ZAM_TYPE_FUNC},   {'I', ZAM_TYPE_INT},     {'L', ZAM_TYPE_LIST},
    {'X', ZAM_TYPE_NONE},    {'O', ZAM_TYPE_OPAQUE}, {'P', ZAM_TYPE_PATTERN}, {'R', ZAM_TYPE_RECORD},
    {'S', ZAM_TYPE_STRING},  {'N', ZAM_TYPE_SUBNET}, {'T', ZAM_TYPE_TABLE},   {'t', ZAM_TYPE_TYPE},
    {'U', ZAM_TYPE_UINT},    {'V', ZAM_TYPE_VECTOR},
};

// Inverse of the above.
static unordered_map<ZAM_Type, char> expr_name_types;

// Given a ZAM_Type, returns the corresponding TypeInfo.
const TypeInfo& find_type_info(ZAM_Type zt) {
    assert(zt != ZAM_TYPE_NONE);

    auto pred = [zt](const TypeInfo& ti) -> bool { return ti.zt == zt; };
    auto ti = std::find_if(ZAM_type_info.begin(), ZAM_type_info.end(), pred);

    assert(ti != ZAM_type_info.end());
    return *ti;
}

// Given a ZAM_Type, return its ZVal accessor.  Takes into account
// some naming inconsistencies between ZVal's and Val's.
string find_type_accessor(ZAM_Type zt, bool is_lhs) {
    if ( zt == ZAM_TYPE_NONE )
        return "";

    string acc = string("As") + find_type_info(zt).accessor;
    if ( is_lhs )
        acc += "Ref";

    return acc + "()";
}

// Maps ZAM operand types to pairs of (1) the C++ name used to declare
// the operand in a method declaration, and (2) the variable name to
// use for the operand.
unordered_map<ZAM_OperandClass, pair<const char*, const char*>> ArgsManager::oc_to_args = {
    {ZAM_OC_AUX, {"OpaqueVals*", "v"}},
    {ZAM_OC_CONSTANT, {"const ConstExpr*", "c"}},
    {ZAM_OC_EVENT_HANDLER, {"EventHandler*", "h"}},
    {ZAM_OC_INT, {"int", "i"}},
    {ZAM_OC_BRANCH, {"int", "i"}},
    {ZAM_OC_GLOBAL, {"int", "i"}},
    {ZAM_OC_STEP_ITER, {"int", "i"}},
    {ZAM_OC_TBL_ITER, {"int", "i"}},
    {ZAM_OC_LIST, {"const ListExpr*", "l"}},
    {ZAM_OC_RECORD_FIELD, {"const NameExpr*", "n"}},
    {ZAM_OC_VAR, {"const NameExpr*", "n"}},

    // The following gets special treatment.
    {ZAM_OC_ASSIGN_FIELD, {"const NameExpr*", "n"}},
};

// The different operand classes that are represented as "raw" integers
// (meaning the slot value is used directly, rather than indexing the frame).
static const set<ZAM_OperandClass> raw_int_oc({ZAM_OC_BRANCH, ZAM_OC_GLOBAL, ZAM_OC_INT, ZAM_OC_STEP_ITER,
                                               ZAM_OC_TBL_ITER});

ArgsManager::ArgsManager(const OCVec& oc_orig, ZAM_InstClass zc) {
    auto oc = oc_orig;
    if ( zc == ZIC_COND )
        // Remove the final entry corresponding to the branch, as
        // we'll automatically generate it subsequently.
        oc.pop_back();

    int n = 0;
    bool add_field = false;

    for ( const auto& ot_i : oc ) {
        if ( ot_i == ZAM_OC_NONE ) { // it had better be the only operand type
            assert(oc.size() == 1);
            break;
        }

        ++n;

        // Start off the argument info using the usual case
        // of (1) same method parameter name as GenInst argument,
        // and (2) not requiring a record field.
        auto& arg_i = oc_to_args[ot_i];
        Arg arg = {arg_i.second, arg_i.first, arg_i.second};

        if ( ot_i == ZAM_OC_ASSIGN_FIELD ) {
            if ( n == 1 ) { // special-case the parameter
                arg.decl_name = "flhs";
                arg.decl_type = "const FieldLHSAssignExpr*";
            }
        }

        args.emplace_back(std::move(arg));
    }

    Differentiate();
}

void ArgsManager::Differentiate() {
    // First, figure out which parameter names are used how often.
    map<string, int> name_count;  // how often the name appears
    map<string, int> usage_count; // how often the name's been used so far
    for ( auto& arg : args ) {
        auto& name = arg.param_name;
        if ( name_count.count(name) == 0 ) {
            name_count[name] = 1;
            usage_count[name] = 0;
        }
        else
            ++name_count[name];
    }

    // Now for each name - whether appearing as an argument or in
    // a declaration - if it's used more than once, then differentiate
    // it.  Note, some names only appear multiple times as arguments
    // when invoking methods, but not in the declarations of the methods
    // themselves.
    for ( auto& arg : args ) {
        auto& decl = arg.decl_name;
        auto& name = arg.param_name;
        bool decl_and_arg_same = decl == name;

        if ( name_count[name] == 1 )
            continue; // it's unique

        auto n = to_string(++usage_count[name]);
        name += n;
        if ( decl_and_arg_same )
            decl += n;
    }

    // Finally, build the full versions of the declaration and parameters.

    for ( auto& arg : args ) {
        if ( ! full_decl.empty() )
            full_decl += ", ";

        full_decl += arg.decl_type + " " + arg.decl_name;

        if ( ! full_params.empty() )
            full_params += ", ";

        full_params += arg.param_name;
        params.push_back(arg.param_name);
    }
}

ZAM_OpTemplate::ZAM_OpTemplate(ZAMGen* _g, string _base_name) : g(_g), base_name(std::move(_base_name)) {
    // Make the base name viable in a C++ name.
    transform(base_name.begin(), base_name.end(), base_name.begin(), dash_to_under);

    cname = base_name;
    transform(cname.begin(), cname.end(), cname.begin(), ::toupper);
}

void ZAM_OpTemplate::Build() {
    op_loc = g->CurrLoc();

    string line;
    while ( g->ScanLine(line) ) {
        if ( line.size() <= 1 )
            break;

        auto words = g->SplitIntoWords(line);
        if ( words.empty() )
            break;

        Parse(words[0], line, words);
    }

    if ( ! op_classes.empty() && ! op_classes_vec.empty() )
        Gripe("\"class\" and \"classes\" are mutually exclusive");

    if ( ! op_classes.empty() || ! op_classes_vec.empty() ) {
        auto nclasses = op_classes.empty() ? op_classes_vec[0].size() : op_classes.size();

        for ( auto& oc : op_classes_vec )
            if ( oc.size() != nclasses )
                Gripe("size mismatch in \"classes\" specifications");

        if ( ! op_types.empty() && op_types.size() != nclasses )
            Gripe("number of \"op-types\" elements must match \"class\"/\"classes\"");
    }

    else if ( ! op_types.empty() )
        Gripe("\"op-types\" can only be used with \"class\"/\"classes\"");
}

void ZAM_OpTemplate::Instantiate() {
    if ( IsPredicate() )
        InstantiatePredicate();

    else if ( op_classes_vec.empty() )
        InstantiateOp(OperandClasses(), IncludesVectorOp());

    else
        for ( auto& ocs : op_classes_vec )
            InstantiateOp(ocs, IncludesVectorOp());
}

void ZAM_OpTemplate::InstantiatePredicate() {
    if ( ! op_classes_vec.empty() )
        Gripe("\"predicate\" cannot include \"classes\"");

    if ( op_classes.empty() )
        Gripe("\"predicate\" requires a \"class\"");

    if ( IncludesVectorOp() )
        Gripe("\"predicate\" cannot include \"vector\"");

    // Build 3 forms: an assignment to an int-value'd $$, a conditional
    // if the evaluation is true, and one if it is not.

    auto orig_eval = eval;
    // Remove trailing '\n' from eval.
    orig_eval.pop_back();

    auto orig_op_classes = op_classes;
    bool no_classes = orig_op_classes[0] == ZAM_OC_NONE;

    // Assignment form.
    op_classes.clear();
    op_classes.push_back(ZAM_OC_VAR);
    if ( ! no_classes )
        op_classes.insert(op_classes.end(), orig_op_classes.begin(), orig_op_classes.end());

    string target_accessor;

    if ( ! op_types.empty() )
        op_types.insert(op_types.begin(), ZAM_TYPE_INT);
    else
        target_accessor = ".AsIntRef()";

    eval = "$$" + target_accessor + " = " + orig_eval + ";";

    InstantiateOp(op_classes, false);

    // Conditional form - branch if not true.

    if ( ! op_types.empty() ) {
        // Remove 'V' at the beginning from the assignment form,
        // and add a 'i' at the end for the branch.
        op_types.erase(op_types.begin());
        op_types.push_back(ZAM_TYPE_INT);
    }

    cname += "_COND";
    op1_flavor = "OP1_READ";
    if ( no_classes )
        op_classes.clear();
    else
        op_classes = orig_op_classes;

    op_classes.push_back(ZAM_OC_BRANCH);

    auto branch_pos = to_string(op_classes.size());
    auto suffix = " )\n\t\t$" + branch_pos;
    eval = "if ( ! (" + orig_eval + ")" + suffix;
    InstantiateOp(op_classes, false);

    // Now the form that branches if true.
    cname = "NOT_" + cname;
    eval = "if ( (" + orig_eval + ")" + suffix;
    InstantiateOp(op_classes, false);
}

void ZAM_OpTemplate::UnaryInstantiate() {
    // First operand is always the frame slot to which this operation
    // assigns the result of the applying unary operator.
    OCVec ocs = {ZAM_OC_VAR};
    ocs.resize(2);

    // Now build versions for a constant operand (maybe not actually
    // needed due to constant folding, but sometimes that gets deferred
    // to run-time) ...
    if ( ! NoConst() ) {
        ocs[1] = ZAM_OC_CONSTANT;
        InstantiateOp(ocs, IncludesVectorOp());
    }

    // ... and for a variable (frame-slot) operand.
    ocs[1] = ZAM_OC_VAR;
    InstantiateOp(ocs, IncludesVectorOp());
}

void ZAM_OpTemplate::Parse(const string& attr, const string& line, const Words& words) {
    int num_args = -1; // -1 = don't enforce
    int nwords = static_cast<int>(words.size());

    if ( attr == "class" ) {
        if ( nwords <= 1 )
            g->Gripe("missing argument", line);

        num_args = 1;
        op_classes = ParseClass(words[1]);
    }

    else if ( attr == "classes" ) {
        if ( nwords <= 1 )
            g->Gripe("missing argument", line);

        num_args = -1;

        for ( int i = 1; i < nwords; ++i )
            op_classes_vec.push_back(ParseClass(words[i]));
    }

    else if ( attr == "op-types" ) {
        if ( words.size() == 1 )
            g->Gripe("op-types needs arguments", line);

        for ( auto i = 1U; i < words.size(); ++i ) {
            auto& w_i = words[i];
            if ( w_i.size() != 1 )
                g->Gripe("bad op-types argument", w_i);

            auto et_c = w_i.c_str()[0];
            if ( type_names.count(et_c) == 0 )
                g->Gripe("bad op-types argument", w_i);

            op_types.push_back(type_names[et_c]);
        }
    }

    else if ( attr == "op1-read" ) {
        num_args = 0;
        SetOp1Flavor("OP1_READ");
    }

    else if ( attr == "op1-read-write" ) {
        num_args = 0;
        SetOp1Flavor("OP1_READ_WRITE");
    }

    else if ( attr == "op1-internal" ) {
        num_args = 0;
        SetOp1Flavor("OP1_INTERNAL");
    }

    else if ( attr == "set-type" ) {
        num_args = 1;
        if ( nwords > 1 )
            SetTypeParam(ExtractTypeParam(words[1]));
    }

    else if ( attr == "set-type2" ) {
        num_args = 1;
        if ( nwords > 1 )
            SetType2Param(ExtractTypeParam(words[1]));
    }

    else if ( attr == "custom-method" )
        SetCustomMethod(g->SkipWords(line, 1));

    else if ( attr == "method-post" )
        SetPostMethod(g->SkipWords(line, 1));

    else if ( attr == "side-effects" ) {
        if ( nwords == 3 )
            SetAssignmentLess(words[1], words[2]);
        else
            // otherwise shouldn't be any arguments
            num_args = 0;

        SetHasSideEffects();
    }

    else if ( attr == "no-eval" ) {
        num_args = 0;
        SetNoEval();
    }

    else if ( attr == "vector" ) {
        num_args = 0;
        SetIncludesVectorOp();
    }

    else if ( attr == "assign-val" ) {
        num_args = 1;
        if ( words.size() > 1 )
            SetAssignVal(words[1]);
    }

    else if ( attr == "eval" ) {
        AddEval(g->SkipWords(line, 1));

        auto addl = GatherEval();
        if ( ! addl.empty() )
            AddEval(addl);
    }

    else if ( attr == "macro" )
        g->ReadMacro(line);

    else
        g->Gripe("unknown template attribute", attr);

    if ( num_args >= 0 && num_args != nwords - 1 )
        g->Gripe("extraneous or missing arguments", line);
}

OCVec ZAM_OpTemplate::ParseClass(const string& spec) const {
    OCVec ocs;

    const char* types = spec.c_str();
    while ( *types ) {
        ZAM_OperandClass oc = ZAM_OC_NONE;

        switch ( *types ) {
            case 'C': oc = ZAM_OC_CONSTANT; break;
            case 'F': oc = ZAM_OC_ASSIGN_FIELD; break;
            case 'H': oc = ZAM_OC_EVENT_HANDLER; break;
            case 'L': oc = ZAM_OC_LIST; break;
            case 'O': oc = ZAM_OC_AUX; break;
            case 'R': oc = ZAM_OC_RECORD_FIELD; break;
            case 'V': oc = ZAM_OC_VAR; break;
            case 'i': oc = ZAM_OC_INT; break;
            case 'b': oc = ZAM_OC_BRANCH; break;
            case 'f': // 'f' = "for" loop
                oc = ZAM_OC_TBL_ITER;
                break;
            case 'g': oc = ZAM_OC_GLOBAL; break;
            case 's': oc = ZAM_OC_STEP_ITER; break;

            case 'X': oc = ZAM_OC_NONE; break;

            default: g->Gripe("bad operand type", spec); break;
        }

        ocs.push_back(oc);

        ++types;
    }

    return ocs;
}

string ZAM_OpTemplate::GatherEval() {
    string res;
    string l;
    while ( g->ScanLine(l) ) {
        if ( l.size() <= 1 || ! isspace(l.c_str()[0]) ) {
            g->PutBack(l);
            return res;
        }

        res += l;
    }

    return res;
}

int ZAM_OpTemplate::ExtractTypeParam(const string& arg) {
    if ( arg == "$$" )
        return 0;

    if ( arg[0] != '$' )
        g->Gripe("bad set-type parameter, should be $n", arg);

    int param = atoi(&arg[1]);

    if ( param <= 0 || param > 2 )
        g->Gripe("bad set-type parameter, should be $1 or $2", arg);

    return param;
}

// Maps an operand type to a character mnemonic used to distinguish
// it from others.
unordered_map<ZAM_OperandClass, char> ZAM_OpTemplate::oc_to_char = {
    {ZAM_OC_AUX, 'O'},      {ZAM_OC_CONSTANT, 'C'}, {ZAM_OC_EVENT_HANDLER, 'H'}, {ZAM_OC_ASSIGN_FIELD, 'F'},
    {ZAM_OC_INT, 'i'},      {ZAM_OC_LIST, 'L'},     {ZAM_OC_NONE, 'X'},          {ZAM_OC_RECORD_FIELD, 'R'},
    {ZAM_OC_VAR, 'V'},      {ZAM_OC_BRANCH, 'b'},   {ZAM_OC_GLOBAL, 'g'},        {ZAM_OC_STEP_ITER, 's'},
    {ZAM_OC_TBL_ITER, 'f'},
};

void ZAM_OpTemplate::InstantiateOp(const OCVec& oc, bool do_vec) {
    auto method = MethodName(oc);

    InstantiateOp(method, oc, ZIC_REGULAR);

    if ( IncludesFieldOp() )
        InstantiateOp(method, oc, ZIC_FIELD);

    if ( do_vec )
        InstantiateOp(method, oc, ZIC_VEC);

    if ( IsConditionalOp() )
        InstantiateOp(method, oc, ZIC_COND);
}

void ZAM_OpTemplate::InstantiateOp(const string& orig_method, const OCVec& oc_orig, ZAM_InstClass zc) {
    auto oc = oc_orig;
    string suffix = "";

    if ( zc == ZIC_FIELD ) {
        // Make room for the offset.
        oc.push_back(ZAM_OC_INT);
        suffix = NoEval() ? "" : "_field";
    }

    else if ( zc == ZIC_COND ) {
        // Remove the assignment and add in the branch.
        oc.erase(oc.begin());
        oc.push_back(ZAM_OC_BRANCH);
        suffix = "_cond";
    }

    else if ( zc == ZIC_VEC ) {
        // Don't generate versions of these for constant operands
        // as those don't exist.
        if ( int(oc.size()) != Arity() + 1 )
            Gripe("vector class/arity mismatch");

        if ( oc[1] == ZAM_OC_CONSTANT )
            return;
        if ( Arity() > 1 && oc[2] == ZAM_OC_CONSTANT )
            return;

        suffix = "_vec";
    }

    auto method = MethodName(oc);

    if ( ! IsInternalOp() )
        InstantiateMethod(method, suffix, oc, zc);

    if ( IsAssignOp() )
        InstantiateAssignOp(oc, suffix);
    else {
        InstantiateEval(oc, suffix, zc);

        if ( HasAssignmentLess() ) {
            auto op_string = "_" + OpSuffix(oc);
            auto op = g->GenOpCode(this, op_string);
            GenAssignmentlessVersion(op);
        }
    }
}

void ZAM_OpTemplate::GenAssignmentlessVersion(const string& op) {
    EmitTo(AssignFlavor);
    Emit("assignmentless_op[" + op + "] = " + AssignmentLessOp() + ";");
    Emit("assignmentless_op_class[" + op + "] = " + AssignmentLessOpClass() + ";");
}

void ZAM_OpTemplate::InstantiateMethod(const string& m, const string& suffix, const OCVec& oc, ZAM_InstClass zc) {
    if ( IsInternalOp() )
        return;

    auto decls = MethodDeclare(oc, zc);

    EmitTo(MethodDecl);
    Emit("const ZAMStmt " + m + suffix + "(" + decls + ");");

    EmitTo(MethodDef);
    Emit("const ZAMStmt ZAMCompiler::" + m + suffix + "(" + decls + ")");
    BeginBlock();

    InstantiateMethodCore(oc, suffix, zc);

    if ( HasPostMethod() )
        Emit(GetPostMethod());

    if ( ! HasCustomMethod() )
        Emit("return AddInst(z);");

    EndBlock();
    NL();
}

void ZAM_OpTemplate::InstantiateMethodCore(const OCVec& oc, const string& suffix, ZAM_InstClass zc) {
    if ( HasCustomMethod() ) {
        Emit(GetCustomMethod());
        return;
    }

    assert(! oc.empty());

    string full_suffix = "_" + OpSuffix(oc) + suffix;

    Emit("ZInstI z;");

    if ( oc[0] == ZAM_OC_AUX ) {
        auto op = g->GenOpCode(this, full_suffix, zc);
        Emit("z = ZInstI(" + op + ");");
        return;
    }

    if ( oc[0] == ZAM_OC_NONE ) {
        auto op = g->GenOpCode(this, full_suffix, zc);
        Emit("z = GenInst(" + op + ");");
        return;
    }

    if ( oc.size() > 1 && oc[1] == ZAM_OC_AUX ) {
        auto op = g->GenOpCode(this, full_suffix, zc);
        Emit("z = ZInstI(" + op + ", Frame1Slot(n, " + op + "));");
        return;
    }

    ArgsManager args(oc, zc);
    BuildInstruction(oc, args.Params(), full_suffix, zc);

    auto& tp = GetTypeParam();
    if ( tp )
        Emit("z.SetType(" + args.NthParam(*tp) + "->GetType());");

    auto& tp2 = GetType2Param();
    if ( tp2 )
        Emit("z.SetType2(" + args.NthParam(*tp2) + "->GetType());");
}

void ZAM_OpTemplate::BuildInstruction(const OCVec& oc, const string& params, const string& suffix, ZAM_InstClass zc) {
    auto op = g->GenOpCode(this, suffix, zc);
    Emit("z = GenInst(" + op + ", " + params + ");");
}

static bool skippable_op_type(ZAM_OperandClass oc) {
    return oc == ZAM_OC_EVENT_HANDLER || oc == ZAM_OC_AUX || oc == ZAM_OC_LIST;
}

string ZAM_OpTemplate::ExpandParams(const OCVec& oc, string eval, const vector<string>& accessors) const {
    auto have_target = eval.find("$$") != string::npos;

    const auto& fl = GetOp1Flavor();
    auto need_target = fl == "OP1_WRITE";

    auto oc_size = oc.size();
    if ( oc_size > 0 ) {
        auto oc0 = oc[0];

        if ( oc0 == ZAM_OC_NONE || oc0 == ZAM_OC_AUX ) {
            --oc_size;
            need_target = false;
        }

        else if ( raw_int_oc.count(oc0) > 0 )
            need_target = false;
    }

    while ( oc_size > 0 && skippable_op_type(oc[oc_size - 1]) )
        --oc_size;

    auto max_param = oc_size;

    if ( need_target && ! have_target )
        Gripe("eval missing $$:", eval);

    if ( have_target ) {
        assert(max_param > 0);
        --max_param;
    }

    bool has_d1 = eval.find("$1") != string::npos;
    bool has_d2 = eval.find("$2") != string::npos;
    bool has_d3 = eval.find("$3") != string::npos;
    bool has_d4 = eval.find("$4") != string::npos;

    switch ( max_param ) {
        case 4:
            if ( ! has_d4 )
                Gripe("eval missing $4", eval);
            [[fallthrough]];
        case 3:
            if ( ! has_d3 )
                Gripe("eval missing $3", eval);
            [[fallthrough]];
        case 2:
            if ( ! has_d2 )
                Gripe("eval missing $2", eval);
            [[fallthrough]];
        case 1:
            if ( ! has_d1 )
                Gripe("eval missing $1", eval);
            [[fallthrough]];
        case 0: break;

        default: Gripe("unexpected param size", to_string(max_param) + " - " + eval); break;
    }

    switch ( max_param ) {
        case 0:
            if ( has_d1 )
                Gripe("extraneous $1 in eval", eval);
            [[fallthrough]];
        case 1:
            if ( has_d2 )
                Gripe("extraneous $2 in eval", eval);
            [[fallthrough]];
        case 2:
            if ( has_d3 )
                Gripe("extraneous $3 in eval", eval);
            [[fallthrough]];
        case 3:
            if ( has_d4 )
                Gripe("extraneous $4 in eval", eval);
            [[fallthrough]];

        case 4: break;

        default: Gripe("unexpected param size", to_string(max_param) + " - " + eval); break;
    }

    int frame_slot = 0;
    bool const_seen = false;
    bool int_seen = false;

    for ( size_t i = 0; i < oc_size; ++i ) {
        string op;
        bool needs_accessor = true;

        switch ( oc[i] ) {
            case ZAM_OC_VAR:
                if ( int_seen )
                    Gripe("'V' type specifier after 'i' specifier", eval);
                op = "frame[z.v" + to_string(++frame_slot) + "]";
                break;

            case ZAM_OC_RECORD_FIELD: op = "frame[z.v" + to_string(++frame_slot) + "]"; break;

            case ZAM_OC_INT:
            case ZAM_OC_BRANCH:
            case ZAM_OC_GLOBAL:
            case ZAM_OC_STEP_ITER:
            case ZAM_OC_TBL_ITER:
                op = "z.v" + to_string(++frame_slot);
                int_seen = true;
                needs_accessor = false;

                if ( oc[i] == ZAM_OC_BRANCH )
                    op = "Branch(" + op + ")";
                else if ( oc[i] == ZAM_OC_STEP_ITER )
                    op = "StepIter(" + op + ")";
                else if ( oc[i] == ZAM_OC_TBL_ITER )
                    op = "TableIter(" + op + ")";
                break;

            case ZAM_OC_CONSTANT:
                if ( const_seen )
                    g->Gripe("double constant", eval.c_str());
                const_seen = true;
                op = "z.c";
                break;

            default: Gripe("unexpected oc type", eval); break;
        }

        if ( needs_accessor ) {
            if ( ! accessors.empty() && ! accessors[i].empty() )
                op += "." + accessors[i];
            else if ( ! op_types.empty() && op_types[i] != ZAM_TYPE_NONE )
                op += "." + find_type_accessor(op_types[i], have_target && i == 0);
        }

        else if ( ! op_types.empty() && oc[i] == ZAM_OC_INT ) {
            if ( op_types[i] == ZAM_TYPE_UINT )
                op = "zeek_uint_t(" + op + ")";
        }

        string pat;
        if ( i == 0 && have_target )
            pat = "\\$\\$";
        else
            pat = "\\$" + to_string(have_target ? i : i + 1);

        auto orig_eval = eval;
        eval = regex_replace(eval, regex(pat), op);
        if ( orig_eval == eval )
            Gripe("no eval sub", pat + " - " + eval);
    }

    return eval;
}

void ZAM_OpTemplate::InstantiateEval(const OCVec& oc, const string& suffix, ZAM_InstClass zc) {
    if ( NoEval() )
        return;

    auto eval = ExpandParams(oc, GetEval(), accessors);

    GenEval(Eval, OpSuffix(oc), suffix, eval, zc);
}

void ZAM_OpTemplate::GenEval(EmitTarget et, const string& oc_str, const string& op_suffix, const string& eval,
                             ZAM_InstClass zc) {
    auto op_code = g->GenOpCode(this, "_" + oc_str + op_suffix, zc);

    if ( et == Eval ) {
        auto oc_str_copy = oc_str;
        if ( zc == ZIC_COND ) {
            auto n = oc_str_copy.size();

            if ( oc_str_copy[n - 1] == 'V' )
                oc_str_copy[n - 1] = 'i';

            else if ( oc_str_copy[n - 1] == 'C' ) {
                if ( oc_str_copy[n - 2] != 'V' )
                    Gripe("bad operator class");

                oc_str_copy[n - 2] = 'C';
                oc_str_copy[n - 1] = 'i';
            }
        }

        GenDesc(op_code, oc_str_copy, eval);
    }

    EmitTo(et);
    Emit("case " + op_code + ":");
    BeginBlock();
    Emit(eval);
    EndBlock();
    EmitUp("break;");
    NL();
}

void ZAM_OpTemplate::GenDesc(const string& op_code, const string& oc_str, const string& eval) {
    StartDesc(op_code, oc_str);
    Emit(eval);
    EndDesc();
}

void ZAM_OpTemplate::StartDesc(const string& op_code, const string& oc_str) {
    EmitTo(OpDesc);
    Emit("{ " + op_code + ",");
    BeginBlock();
    Emit("\"" + oc_str + "\",");

    if ( op_types.empty() )
        Emit("\"\",");
    else {
        string ots;
        for ( auto typ : op_types ) {
            if ( typ == ZAM_TYPE_DEFAULT )
                ots += "X";
            else
                ots += expr_name_types[typ];
        }

        Emit("\"" + ots + "\", ");
    }

    StartString();
}

void ZAM_OpTemplate::EndDesc() {
    EndString();
    EndBlock();
    Emit("},");
}

void ZAM_OpTemplate::InstantiateAssignOp(const OCVec& oc, const string& suffix) {
    // First, create a generic version of the operand, which the
    // ZAM compiler uses to find specific-flavored versions.
    auto oc_str = OpSuffix(oc);
    auto op_string = "_" + oc_str;
    auto generic_op = g->GenOpCode(this, op_string);
    auto flavor_ind = "assignment_flavor[" + generic_op + "]";

    EmitTo(AssignFlavor);
    Emit(flavor_ind + " = empty_map;");

    const auto& eval = GetEval();
    const auto& v = GetAssignVal();

    for ( auto& ti : ZAM_type_info ) {
        auto op = g->GenOpCode(this, op_string + "_" + ti.suffix);

        if ( IsInternalOp() ) {
            EmitTo(AssignFlavor);
            Emit(flavor_ind + "[" + ti.tag + "] = " + op + ";");

            if ( HasAssignmentLess() )
                GenAssignmentlessVersion(op);
        }

        StartDesc(op, oc_str);
        GenAssignOpCore(oc, eval, ti.accessor, ti.is_managed);
        if ( ! post_eval.empty() )
            Emit(post_eval);
        EndDesc();

        EmitTo(Eval);
        Emit("case " + op + ":");
        BeginBlock();
        GenAssignOpCore(oc, eval, ti.accessor, ti.is_managed);
        if ( ! post_eval.empty() )
            Emit(post_eval);
        Emit("break;");
        EndBlock();
    }

    post_eval.clear();
}

void ZAM_OpTemplate::GenAssignOpCore(const OCVec& oc, const string& eval, const string& accessor, bool is_managed) {
    if ( HasAssignVal() ) {
        GenAssignOpValCore(oc, eval, accessor, is_managed);
        return;
    }

    if ( ! eval.empty() )
        g->Gripe("assign-op should not have an \"eval\"", eval);

    auto lhs_field = (oc[0] == ZAM_OC_ASSIGN_FIELD);
    auto rhs_field = lhs_field && oc.size() > 3 && (oc[3] == ZAM_OC_INT);
    auto constant_op = (oc[1] == ZAM_OC_CONSTANT);

    string rhs = constant_op ? "z.c" : "frame[z.v2]";

    auto acc = ".As" + accessor + "()";

    if ( accessor == "Any" && constant_op && ! rhs_field ) {
        // "any_val = constant" or "x$any_val = constant".
        //
        // These require special-casing, because to avoid going
        // through a CoerceToAny operation, we allow expressing
        // these directly.  They don't fit with the usual assignment
        // paradigm since the RHS differs in type from the LHS.
        Emit("auto v = z.c.ToVal(Z_TYPE);");

        if ( lhs_field ) {
            Emit("auto r = frame[z.v1].AsRecord();");
            Emit("auto& f = DirectField(r, z.v2);");
        }
        else
            Emit("auto& f = frame[z.v1];");

        Emit("zeek::Unref(f.ManagedVal());");
        Emit("f = ZVal(v.release());");
    }

    else if ( rhs_field ) {
        // The following is counter-intuitive, but comes from the
        // fact that we build out the instruction parameters as
        // an echo of the method parameters, and for this case that
        // means that the RHS field offset comes *before*, not after,
        // the LHS field offset.
        auto lhs_offset = constant_op ? 3 : 4;
        auto rhs_offset = lhs_offset - 1;

        Emit("auto v = DirectOptField(" + rhs + ".AsRecord(), z.v" + to_string(rhs_offset) +
             "); // note, RHS field before LHS field\n");

        Emit("if ( ! v )");
        BeginBlock();
        Emit("ZAM_run_time_error(Z_LOC, \"field value missing\");");
        EndBlock();

        Emit("else");
        BeginBlock();
        auto slot = "z.v" + to_string(lhs_offset);
        Emit("auto r = frame[z.v1].AsRecord();");
        Emit("auto& f = DirectField(r, " + slot + "); // note, LHS field after RHS field\n");

        if ( is_managed ) {
            Emit("zeek::Ref((*v)" + acc + ");");
            Emit("zeek::Unref(f.ManagedVal());");
        }

        Emit("f = *v;");

        if ( lhs_field )
            Emit("r->Modified();");

        EndBlock();
    }

    else {
        if ( is_managed )
            Emit("zeek::Ref(" + rhs + acc + ");");

        if ( lhs_field ) {
            auto lhs_offset = constant_op ? 2 : 3;
            auto slot = "z.v" + to_string(lhs_offset);
            Emit("auto r = frame[z.v1].AsRecord();");
            Emit("auto& f = DirectField(r, " + slot + ");");

            if ( is_managed )
                Emit("zeek::Unref(f.ManagedVal());");

            Emit("f = " + rhs + ";");
            Emit("r->Modified();");
        }

        else {
            if ( is_managed )
                Emit("zeek::Unref(frame[z.v1].ManagedVal());");

            Emit("frame[z.v1] = ZVal(" + rhs + acc + ");");
        }
    }
}

void ZAM_OpTemplate::GenAssignOpValCore(const OCVec& oc, const string& orig_eval, const string& accessor,
                                        bool is_managed) {
    const auto& v = GetAssignVal();

    // Maps Zeek types to how to get the underlying value from a ValPtr.
    static unordered_map<string, string> val_accessors = {
        {"Addr", "->AsAddrVal()"},     {"Any", ".get()"},
        {"Count", "->AsCount()"},      {"Double", "->AsDouble()"},
        {"Int", "->AsInt()"},          {"Pattern", "->AsPatternVal()"},
        {"String", "->AsStringVal()"}, {"SubNet", "->AsSubNetVal()"},
        {"Table", "->AsTableVal()"},   {"Vector", "->AsVectorVal()"},
        {"File", "->AsFile()"},        {"Func", "->AsFunc()"},
        {"List", "->AsListVal()"},     {"Opaque", "->AsOpaqueVal()"},
        {"Record", "->AsRecordVal()"}, {"Type", "->AsTypeVal()"},
    };

    const auto& val_accessor = val_accessors[accessor];

    string rhs;
    if ( IsInternalOp() )
        rhs = v + val_accessor;
    else
        rhs = v + ".As" + accessor + "()";

    auto eval = orig_eval;

    if ( is_managed ) {
        eval += string("auto rhs = ") + rhs + ";\n";
        eval += "zeek::Ref(rhs);\n";
        eval += "Unref($$.ManagedVal());\n";
        eval += "$$ = ZVal(rhs);\n";
    }
    else
        eval += "$$ = ZVal(" + rhs + ");\n";

    Emit(ExpandParams(oc, eval));
}

string ZAM_OpTemplate::MethodName(const OCVec& oc) const { return base_name + OpSuffix(oc); }

string ZAM_OpTemplate::MethodDeclare(const OCVec& oc, ZAM_InstClass zc) {
    ArgsManager args(oc, zc);
    return args.Decls();
}

string ZAM_OpTemplate::OpSuffix(const OCVec& oc) const {
    string os;
    for ( auto& o : oc )
        os += oc_to_char[o];
    return os;
}

string ZAM_OpTemplate::SkipWS(const string& s) const {
    auto sp = s.c_str();
    while ( *sp && isspace(*sp) )
        ++sp;

    return sp;
}

void ZAM_OpTemplate::Emit(const string& s) { g->Emit(curr_et, s); }

void ZAM_OpTemplate::EmitNoNL(const string& s) {
    g->SetNoNL(true);
    Emit(s);
    g->SetNoNL(false);
}

void ZAM_OpTemplate::IndentUp() { g->IndentUp(); }

void ZAM_OpTemplate::IndentDown() { g->IndentDown(); }

void ZAM_OpTemplate::StartString() { g->StartString(); }

void ZAM_OpTemplate::EndString() { g->EndString(); }

void ZAM_OpTemplate::Gripe(const char* msg) const { g->Gripe(msg, op_loc); }

void ZAM_OpTemplate::Gripe(string msg, string addl) const {
    auto full_msg = msg + ": " + addl;
    Gripe(full_msg.c_str());
}

void ZAM_UnaryOpTemplate::Instantiate() { UnaryInstantiate(); }

void ZAM_DirectUnaryOpTemplate::Instantiate() {
    EmitTo(DirectDef);
    Emit("case EXPR_" + cname + ":\treturn " + direct + "(lhs, rhs);");
}

ZAM_ExprOpTemplate::ZAM_ExprOpTemplate(ZAMGen* _g, string _base_name) : ZAM_OpTemplate(_g, std::move(_base_name)) {
    static bool did_map_init = false;

    if ( ! did_map_init ) { // Create the inverse mapping.
        for ( auto& tn : type_names )
            expr_name_types[tn.second] = tn.first;

        did_map_init = true;
    }
}

void ZAM_ExprOpTemplate::Parse(const string& attr, const string& line, const Words& words) {
    if ( attr == "op-type" ) {
        if ( words.size() == 1 )
            g->Gripe("op-type needs arguments", line);

        for ( auto i = 1U; i < words.size(); ++i ) {
            auto& w_i = words[i];
            if ( w_i.size() != 1 )
                g->Gripe("bad op-type argument", w_i);

            auto et_c = w_i.c_str()[0];
            if ( type_names.count(et_c) == 0 )
                g->Gripe("bad op-type argument", w_i);

            AddExprType(type_names[et_c]);
        }
    }

    else if ( attr == "includes-field-op" ) {
        if ( words.size() != 1 )
            g->Gripe("includes-field-op does not take any arguments", line);

        SetIncludesFieldOp();
    }

    else if ( attr == "eval-type" ) {
        if ( words.size() < 3 )
            g->Gripe("eval-type needs type and evaluation", line);

        auto& type = words[1];
        if ( type.size() != 1 )
            g->Gripe("bad eval-type type", type);

        auto type_c = type.c_str()[0];
        if ( type_names.count(type_c) == 0 )
            g->Gripe("bad eval-type type", type);

        auto zt = type_names[type_c];

        if ( expr_types.count(zt) == 0 )
            g->Gripe("eval-type type not present in eval-type", type);

        auto eval = g->SkipWords(line, 2);
        eval += GatherEval();
        AddEvalSet(zt, eval);
    }

    else if ( attr == "eval-mixed" ) {
        if ( words.size() < 4 )
            g->Gripe("eval-mixed needs types and evaluation", line);

        auto& type1 = words[1];
        auto& type2 = words[2];
        if ( type1.size() != 1 || type2.size() != 1 )
            g->Gripe("bad eval-mixed types", line);

        auto type_c1 = type1.c_str()[0];
        auto type_c2 = type2.c_str()[0];
        if ( type_names.count(type_c1) == 0 || type_names.count(type_c2) == 0 )
            g->Gripe("bad eval-mixed types", line);

        auto et1 = type_names[type_c1];
        auto et2 = type_names[type_c2];

        auto eval = g->SkipWords(line, 3);
        eval += GatherEval();
        AddEvalSet(et1, et2, eval);
    }

    else if ( attr == "precheck" ) {
        if ( words.size() < 2 )
            g->Gripe("precheck needs evaluation", line);

        auto eval = g->SkipWords(line, 1);
        eval += GatherEval();
        eval.pop_back();

        SetPreCheck(eval);
    }

    else if ( attr == "precheck-action" ) {
        if ( words.size() < 2 )
            g->Gripe("precheck-action needs evaluation", line);

        auto eval = g->SkipWords(line, 1);
        eval += GatherEval();
        eval.pop_back();

        SetPreCheckAction(eval);
    }

    else if ( attr == "explicit-result-type" ) {
        if ( words.size() != 1 )
            g->Gripe("extraneous argument to explicit-result-type", line);
        SetHasExplicitResultType();
    }

    else
        // Not an attribute specific to expr-op's.
        ZAM_OpTemplate::Parse(attr, line, words);
}

void ZAM_ExprOpTemplate::Instantiate() {
    if ( ! op_classes_vec.empty() )
        Gripe("expressions cannot use \"classes\"");

    InstantiateOp(OperandClasses(), IncludesVectorOp());

    if ( op_classes.size() > 1 && op_classes[1] == ZAM_OC_CONSTANT )
        InstantiateC1(op_classes, op_classes.size() - 1);
    if ( op_classes.size() > 2 && op_classes[2] == ZAM_OC_CONSTANT )
        InstantiateC2(op_classes, op_classes.size() - 1);
    if ( op_classes.size() > 3 && op_classes[3] == ZAM_OC_CONSTANT )
        InstantiateC3(op_classes);

    bool all_var = true;
    for ( auto i = 1U; i < op_classes.size(); ++i )
        if ( op_classes[i] != ZAM_OC_VAR )
            all_var = false;

    if ( all_var )
        InstantiateV(op_classes);

    if ( op_classes.size() == 3 && op_classes[1] == ZAM_OC_RECORD_FIELD && op_classes[2] == ZAM_OC_INT )
        InstantiateV(op_classes);
}

void ZAM_ExprOpTemplate::InstantiateC1(const OCVec& ocs, size_t arity) {
    string args = "lhs, r1->AsConstExpr()";

    if ( arity == 1 && ocs[0] == ZAM_OC_RECORD_FIELD )
        args += ", rhs->AsFieldExpr()->Field()";

    else if ( arity > 1 ) {
        args += ", ";

        if ( ocs[2] == ZAM_OC_RECORD_FIELD )
            args += "rhs->AsFieldExpr()->Field()";
        else
            args += "r2->AsNameExpr()";
    }

    auto m = MethodName(ocs);

    EmitTo(C1Def);

    EmitNoNL("case EXPR_" + cname + ":");

    EmitUp("return " + m + "(" + args + ");");

    if ( IncludesFieldOp() ) {
        EmitTo(C1FieldDef);
        Emit("case EXPR_" + cname + ":\treturn " + m + "i_field(" + args + ", field);");
    }
}

void ZAM_ExprOpTemplate::InstantiateC2(const OCVec& ocs, size_t arity) {
    string args = "lhs, r1->AsNameExpr(), r2->AsConstExpr()";

    if ( arity == 3 )
        args += ", r3->AsNameExpr()";

    auto method = MethodName(ocs);
    auto m = method.c_str();

    EmitTo(C2Def);
    Emit("case EXPR_" + cname + ":\treturn " + m + "(" + args + ");");

    if ( IncludesFieldOp() ) {
        EmitTo(C2FieldDef);
        Emit("case EXPR_" + cname + ":\treturn " + m + "i_field(" + args + ", field);");
    }
}

void ZAM_ExprOpTemplate::InstantiateC3(const OCVec& ocs) {
    EmitTo(C3Def);
    Emit("case EXPR_" + cname + ":\treturn " + MethodName(ocs) +
         "(lhs, r1->AsNameExpr(), r2->AsNameExpr(), r3->AsConstExpr());");
}

void ZAM_ExprOpTemplate::InstantiateV(const OCVec& ocs) {
    auto m = MethodName(ocs);

    string args = "lhs, r1->AsNameExpr()";

    if ( ocs.size() >= 3 ) {
        if ( ocs[2] == ZAM_OC_INT ) {
            string acc_flav = IncludesFieldOp() ? "Has" : "";
            args += ", rhs->As" + acc_flav + "FieldExpr()->Field()";
        }
        else
            args += ", r2->AsNameExpr()";

        if ( ocs.size() == 4 )
            args += ", r3->AsNameExpr()";
    }

    EmitTo(VDef);
    EmitNoNL("case EXPR_" + cname + ":");

    if ( IncludesVectorOp() )
        DoVectorCase(m, args);
    else
        EmitUp("return " + m + "(" + args + ");");

    if ( IncludesFieldOp() ) {
        string suffix = NoEval() ? "" : "_field";
        EmitTo(VFieldDef);
        Emit("case EXPR_" + cname + ":\treturn " + m + "i" + suffix + "(" + args + ", field);");
    }
}

void ZAM_ExprOpTemplate::DoVectorCase(const string& m, const string& args) {
    NL();
    IndentUp();
    Emit("if ( rt->Tag() == TYPE_VECTOR )");
    EmitUp("return " + m + "_vec(" + args + ");");
    Emit("else");
    EmitUp("return " + m + "(" + args + ");");
    IndentDown();
}

void ZAM_ExprOpTemplate::BuildInstructionCore(const string& params, const string& suffix, ZAM_InstClass zc) {
    Emit("auto tag1 = t->Tag();");
    Emit("auto i_t1 = t->InternalType();");

    int ncases = 0;

    if ( zc != ZIC_VEC )
        for ( auto& [et1, et2_map] : eval_mixed_set )
            for ( auto& [et2, eval] : et2_map )
                GenMethodTest(et1, et2, params, suffix, ++ncases > 1, zc);

    bool do_default = false;

    for ( auto zt : ExprTypes() ) {
        if ( zt == ZAM_TYPE_DEFAULT )
            do_default = true;
        else if ( zt == ZAM_TYPE_NONE )
            continue;
        else
            GenMethodTest(zt, zt, params, suffix, ++ncases > 1, zc);
    }

    Emit("else");

    if ( do_default ) {
        auto op = g->GenOpCode(this, suffix, zc);
        EmitUp("z = GenInst(" + op + ", " + params + ");");
    }

    else
        EmitUp("reporter->InternalError(\"bad tag when generating method core\");");
}

void ZAM_ExprOpTemplate::GenMethodTest(ZAM_Type et1, ZAM_Type et2, const string& params, const string& suffix,
                                       bool do_else, ZAM_InstClass zc) {
    // Maps ZAM_Type's to the information needed (variable name,
    // constant to compare it against) to identify using an "if" test
    // that a given AST Expr node employs the given type of operand.
    static map<ZAM_Type, pair<string, string>> if_tests = {
        {ZAM_TYPE_ADDR, {"i_t", "TYPE_INTERNAL_ADDR"}},
        {ZAM_TYPE_ANY, {"tag", "TYPE_ANY"}},
        {ZAM_TYPE_DOUBLE, {"i_t", "TYPE_INTERNAL_DOUBLE"}},
        {ZAM_TYPE_FILE, {"tag", "TYPE_FILE"}},
        {ZAM_TYPE_FUNC, {"tag", "TYPE_FUNC"}},
        {ZAM_TYPE_INT, {"i_t", "TYPE_INTERNAL_INT"}},
        {ZAM_TYPE_LIST, {"tag", "TYPE_LIST"}},
        {ZAM_TYPE_OPAQUE, {"tag", "TYPE_OPAQUE"}},
        {ZAM_TYPE_PATTERN, {"tag", "TYPE_PATTERN"}},
        {ZAM_TYPE_RECORD, {"tag", "TYPE_RECORD"}},
        {ZAM_TYPE_STRING, {"i_t", "TYPE_INTERNAL_STRING"}},
        {ZAM_TYPE_SUBNET, {"i_t", "TYPE_INTERNAL_SUBNET"}},
        {ZAM_TYPE_TABLE, {"tag", "TYPE_TABLE"}},
        {ZAM_TYPE_TYPE, {"tag", "TYPE_TYPE"}},
        {ZAM_TYPE_UINT, {"i_t", "TYPE_INTERNAL_UNSIGNED"}},
        {ZAM_TYPE_VECTOR, {"tag", "TYPE_VECTOR"}},
    };

    if ( if_tests.count(et1) == 0 || if_tests.count(et2) == 0 )
        Gripe("bad op-type");

    const auto& [var, val] = if_tests[et1];
    auto if_var1 = var + "1";

    string test = if_var1 + " == " + val;

    if ( Arity() > 1 ) {
        const auto& [var2, val2] = if_tests[et2];
        auto if_var2 = var2 + "2";
        test = test + " && " + if_var2 + " == " + val2;
    }

    test = "if ( " + test + " )";
    if ( do_else )
        test = "else " + test;

    Emit(test);

    auto op_suffix = suffix + "_" + expr_name_types[et1];
    if ( et2 != et1 )
        op_suffix += expr_name_types[et2];

    auto op = g->GenOpCode(this, op_suffix, zc);
    EmitUp("z = GenInst(" + op + ", " + params + ");");
}

EvalInstance::EvalInstance(ZAM_Type _lhs_et, ZAM_Type _op1_et, ZAM_Type _op2_et, string _eval, bool _is_def) {
    lhs_et = _lhs_et;
    op1_et = _op1_et;
    op2_et = _op2_et;
    eval = std::move(_eval);
    is_def = _is_def;
}

string EvalInstance::LHSAccessor(bool is_ptr) const {
    if ( lhs_et == ZAM_TYPE_NONE || lhs_et == ZAM_TYPE_DEFAULT )
        return "";

    string deref = is_ptr ? "->" : ".";
    string acc = find_type_accessor(lhs_et, true);

    return deref + acc;
}

string EvalInstance::Accessor(ZAM_Type zt, bool is_ptr) const {
    if ( zt == ZAM_TYPE_NONE || zt == ZAM_TYPE_DEFAULT )
        return "";

    string deref = is_ptr ? "->" : ".";
    return deref + "As" + find_type_info(zt).accessor + "()";
}

string EvalInstance::OpMarker() const {
    if ( op1_et == ZAM_TYPE_DEFAULT || op1_et == ZAM_TYPE_NONE )
        return "";

    if ( op1_et == op2_et )
        return "_" + find_type_info(op1_et).suffix;

    return "_" + find_type_info(op1_et).suffix + find_type_info(op2_et).suffix;
}

void ZAM_ExprOpTemplate::InstantiateEval(const OCVec& oc_orig, const string& suffix, ZAM_InstClass zc) {
    if ( (HasPreCheck() || HasPreCheckAction()) && (! HasPreCheck() || ! HasPreCheckAction()) )
        Gripe("precheck and precheck-action must be used together");

    auto oc = oc_orig;

    if ( expr_types.empty() ) {
        // No operand types to expand over. This happens for
        // some "non-uniform" operations.
        ZAM_OpTemplate::InstantiateEval(oc, suffix, zc);
        return;
    }

    auto oc_str = OpSuffix(oc);

    // Some of these might not wind up being used, but no harm in
    // initializing them in case they are.
    string lhs, op1, op2;
    string branch_target = "z.v";

    EmitTarget emit_target = Eval;

    if ( zc == ZIC_VEC ) {
        lhs = "vec1[i]";
        op1 = "vec2[i]";
        op2 = "vec3[i]";

        emit_target = Arity() == 1 ? Vec1Eval : Vec2Eval;
    }

    else {
        lhs = "frame[z.v1]";

        // First compute the offsets into oc for the operands.
        auto op1_offset = zc == ZIC_COND ? 0 : 1;
        bool oc1_const = oc[op1_offset] == ZAM_OC_CONSTANT;
        bool oc2_const = Arity() > 1 && oc[op1_offset + 1] == ZAM_OC_CONSTANT;

        // Now the frame slots.
        auto op1_slot = op1_offset + 1;
        auto op2_slot = op1_slot + 1;

        if ( oc1_const ) {
            op1 = "z.c";
            --op2_slot;
            if ( zc == ZIC_COND )
                branch_target += "2";
        }
        else {
            op1 = "frame[z.v" + to_string(op1_slot) + "]";

            if ( zc == ZIC_COND ) {
                if ( Arity() > 1 && ! oc2_const )
                    branch_target += "3";
                else
                    branch_target += "2";
            }
        }

        if ( oc2_const )
            op2 = "z.c";
        else
            op2 = "frame[z.v" + to_string(op2_slot) + "]";

        if ( zc == ZIC_FIELD ) {
            // Compute the slot holding the field offset.

            auto f =
                // The first slots are taken up by the
                // assignment slot and the operands ...
                Arity() + 1 +
                // ... and slots are numbered starting at 1.
                +1;

            if ( oc1_const || oc2_const )
                // One of the operand slots won't be needed
                // due to the presence of a constant.
                // (It's never the case that both operands
                // are constants - those instead get folded.)
                --f;

            lhs = "DirectField(" + lhs + ".AsRecord(), z.v" + to_string(f) + ")";
        }
    }

    vector<EvalInstance> eval_instances;

    for ( auto zt : expr_types ) {
        // Support for "op-type X" meaning "allow empty evaluation",
        // as well as "evaluation is generic".
        if ( zt == ZAM_TYPE_NONE && GetEval().empty() )
            continue;

        auto is_def = eval_set.count(zt) == 0;
        string eval = is_def ? GetEval() : eval_set[zt];
        auto lhs_et = IsConditionalOp() ? ZAM_TYPE_INT : zt;
        eval_instances.emplace_back(lhs_et, zt, zt, eval, is_def);
    }

    if ( zc != ZIC_VEC )
        for ( const auto& em1 : eval_mixed_set ) {
            auto et1 = em1.first;
            for ( const auto& em2 : em1.second ) {
                auto et2 = em2.first;

                // For the LHS, either its expression type is
                // ignored, or if it's a conditional, so just
                // note it for the latter.
                auto lhs_et = ZAM_TYPE_INT;
                eval_instances.emplace_back(lhs_et, et1, et2, em2.second, false);
            }
        }

    for ( auto& ei : eval_instances ) {
        op_types.clear();

        auto lhs_accessor = ei.LHSAccessor();
        if ( HasExplicitResultType() ) {
            op_types.push_back(ZAM_TYPE_NONE);
            lhs_accessor = "";
        }
        else if ( zc == ZIC_FIELD )
            op_types.push_back(ZAM_TYPE_RECORD);
        else if ( zc != ZIC_COND )
            op_types.push_back(ei.LHS_ET());

        string lhs_ei = lhs;
        if ( zc != ZIC_VEC )
            lhs_ei += lhs_accessor;

        op_types.push_back(ei.Op1_ET());
        if ( Arity() > 1 )
            op_types.push_back(ei.Op2_ET());

        if ( zc == ZIC_FIELD )
            op_types.push_back(ZAM_TYPE_INT);

        else if ( zc == ZIC_COND )
            op_types.push_back(ZAM_TYPE_INT);

        else if ( zc == ZIC_VEC ) {
            // Above isn't applicable, since we use helper
            // functions.
            op_types.clear();
            op_types.push_back(ZAM_TYPE_VECTOR);
            op_types.push_back(ZAM_TYPE_VECTOR);

            if ( Arity() > 1 )
                op_types.push_back(ZAM_TYPE_VECTOR);
        }

        auto op1_ei = op1 + ei.Op1Accessor(zc == ZIC_VEC);
        auto op2_ei = op2 + ei.Op2Accessor(zc == ZIC_VEC);

        auto eval = SkipWS(ei.Eval());

        auto has_target = eval.find("$$") != string::npos;

        if ( zc == ZIC_VEC ) {
            const char* rhs;
            if ( has_target )
                rhs = "\\$\\$ = ([^;\n]*)";
            else
                rhs = "^[^;\n]*";

            auto replacement = VecEvalRE(has_target);

            eval = regex_replace(eval, regex(rhs), replacement, std::regex_constants::match_not_null);
        }

        auto is_none = ei.LHS_ET() == ZAM_TYPE_NONE;
        auto is_default = ei.LHS_ET() == ZAM_TYPE_DEFAULT;

        if ( ! is_none && ! is_default && find_type_info(ei.LHS_ET()).is_managed && ! HasExplicitResultType() ) {
            auto pre = "auto hold_lhs = " + lhs;

            if ( zc == ZIC_VEC )
                // For vectors, we have to check for whether
                // the previous value is present, or a hole.
                pre += string(" ? ") + lhs + "->";
            else
                pre += ".";

            pre += "ManagedVal()";

            if ( zc == ZIC_VEC )
                pre += " : nullptr";

            pre += ";\n\t";

            auto post = "\tUnref(hold_lhs);";

            eval = pre + eval + post;
        }

        eval = regex_replace(eval, regex("\\$1"), op1_ei);
        eval = regex_replace(eval, regex("\\$2"), op2_ei);

        string pre, post;

        if ( HasPreCheck() ) {
            pre = "if ( " + GetPreCheck() + ")\n\t{\n\t" + GetPreCheckAction() + "\n\t}\n\telse\n\t{\n\t";
            post = "\n\t}";
        }

        pre = regex_replace(pre, regex("\\$1"), op1_ei);
        pre = regex_replace(pre, regex("\\$2"), op2_ei);

        if ( has_target )
            eval = regex_replace(eval, regex("\\$\\$"), lhs_ei);

        else if ( zc == ZIC_COND ) {
            // Aesthetics: get rid of trailing newlines.
            eval = regex_replace(eval, regex("\n"), "");

            eval = "if ( ! (" + eval + ") ) " + "Branch(" + branch_target + ")";
        }

        else if ( ! is_none && (ei.IsDefault() || IsConditionalOp()) ) {
            eval = lhs_ei + " = " + eval;

            // Ensure a single terminating semicolon.
            eval = regex_replace(eval, regex(";*\n"), ";\n");
        }

        eval = pre + eval + post;

        auto full_suffix = suffix + ei.OpMarker();

        GenEval(emit_target, oc_str, full_suffix, eval, zc);

        if ( zc == ZIC_VEC ) {
            string dispatch_params = "frame[z.v1].AsVectorRef(), frame[z.v2].AsVector()";

            if ( Arity() == 2 )
                dispatch_params += ", frame[z.v3].AsVector()";

            auto op_code = g->GenOpCode(this, "_" + oc_str + full_suffix);
            auto dispatch = "vec_exec(" + op_code + ", Z_TYPE, " + dispatch_params + ", z);";

            GenEval(Eval, oc_str, full_suffix, dispatch, zc);
        }
    }
}

void ZAM_UnaryExprOpTemplate::Parse(const string& attr, const string& line, const Words& words) {
    if ( attr == "no-const" ) {
        if ( words.size() != 1 )
            g->Gripe("extraneous argument to no-const", line);

        SetNoConst();
    }

    else
        ZAM_ExprOpTemplate::Parse(attr, line, words);
}

void ZAM_UnaryExprOpTemplate::Instantiate() {
    UnaryInstantiate();

    OCVec ocs = {ZAM_OC_VAR, ZAM_OC_CONSTANT};

    if ( ! NoConst() )
        InstantiateC1(ocs, 1);

    ocs[1] = ZAM_OC_VAR;
    InstantiateV(ocs);
}

void ZAM_UnaryExprOpTemplate::BuildInstruction(const OCVec& oc, const string& params, const string& suffix,
                                               ZAM_InstClass zc) {
    const auto& ets = ExprTypes();

    if ( ets.size() == 1 && ets.count(ZAM_TYPE_NONE) == 1 ) {
        ZAM_ExprOpTemplate::BuildInstruction(oc, params, suffix, zc);
        return;
    }

    auto constant_op = oc[1] == ZAM_OC_CONSTANT;
    string type_src = constant_op ? "c" : "n2";

    if ( oc[0] == ZAM_OC_ASSIGN_FIELD ) {
        type_src = constant_op ? "n" : "n1";
        Emit("auto " + type_src + " = flhs->GetOp1()->AsNameExpr();");
        Emit("const auto& t = flhs->GetType();");
    }

    else {
        if ( IsAssignOp() )
            type_src = constant_op ? "n" : "n1";

        auto type_suffix = zc == ZIC_VEC ? "->Yield();" : ";";
        Emit("const auto& t = " + type_src + "->GetType()" + type_suffix);
    }

    BuildInstructionCore(params, suffix, zc);

    if ( IsAssignOp() && IsFieldOp() )
        // These can't take the type from the LHS variable, since
        // that's the enclosing record and not the field within it.
        Emit("z.SetType(t);");

    else if ( zc == ZIC_VEC ) {
        if ( constant_op )
            Emit("z.SetType(n->GetType());");
        else
            Emit("z.SetType(n1->GetType());");
    }
}

ZAM_AssignOpTemplate::ZAM_AssignOpTemplate(ZAMGen* _g, string _base_name)
    : ZAM_UnaryExprOpTemplate(_g, std::move(_base_name)) {
    // Assignments apply to every valid form of ExprType.
    for ( auto& etn : type_names ) {
        auto zt = etn.second;
        if ( zt != ZAM_TYPE_NONE && zt != ZAM_TYPE_DEFAULT )
            AddExprType(zt);
    }
}

void ZAM_AssignOpTemplate::Parse(const string& attr, const string& line, const Words& words) {
    if ( attr == "field-op" ) {
        if ( words.size() != 1 )
            g->Gripe("field-op does not take any arguments", line);

        SetFieldOp();
    }

    else
        ZAM_OpTemplate::Parse(attr, line, words);
}

void ZAM_AssignOpTemplate::Instantiate() {
    if ( op_classes.size() != 1 )
        Gripe("operation needs precisely one \"type\"");
    if ( ! op_classes_vec.empty() )
        Gripe("operation cannot use \"classes\"");

    OCVec ocs;
    ocs.push_back(op_classes[0]);

    // Build constant/variable versions ...
    ocs.push_back(ZAM_OC_CONSTANT);

    if ( ocs[0] == ZAM_OC_RECORD_FIELD || ocs[0] == ZAM_OC_ASSIGN_FIELD )
        ocs.push_back(ZAM_OC_INT);

    InstantiateOp(ocs, false);
    if ( IsFieldOp() )
        InstantiateC1(ocs, 1);

    ocs[1] = ZAM_OC_VAR;
    InstantiateOp(ocs, false);

    // ... and for assignments to fields, additional field versions.
    if ( ocs[0] == ZAM_OC_ASSIGN_FIELD ) {
        ocs.push_back(ZAM_OC_INT);
        InstantiateOp(ocs, false);

        ocs[1] = ZAM_OC_CONSTANT;
        InstantiateOp(ocs, false);
    }

    else if ( IsFieldOp() )
        InstantiateV(ocs);
}

void ZAM_BinaryExprOpTemplate::Instantiate() {
    // As usual, the first slot receives the operator's result.
    OCVec ocs = {ZAM_OC_VAR};
    ocs.resize(3);

    // Build each combination for constant/variable operand,
    // except skip constant/constant as that is always folded.

    // We only include vector operations when both operands
    // are non-constants.

    ocs[1] = ZAM_OC_CONSTANT;
    ocs[2] = ZAM_OC_VAR;
    InstantiateOp(ocs, false);

    if ( ! IsInternalOp() )
        InstantiateC1(ocs, 2);

    ocs[1] = ZAM_OC_VAR;
    ocs[2] = ZAM_OC_CONSTANT;
    InstantiateOp(ocs, false);

    if ( ! IsInternalOp() )
        InstantiateC2(ocs, 2);

    ocs[2] = ZAM_OC_VAR;
    InstantiateOp(ocs, IncludesVectorOp());

    if ( ! IsInternalOp() )
        InstantiateV(ocs);
}

void ZAM_BinaryExprOpTemplate::BuildInstruction(const OCVec& oc, const string& params, const string& suffix,
                                                ZAM_InstClass zc) {
    auto constant_op = oc[1] == ZAM_OC_CONSTANT;
    string type_src = constant_op ? "c" : "n2";
    auto type_suffix = zc == ZIC_VEC ? "->Yield();" : ";";
    Emit("const auto& t = " + type_src + "->GetType()" + type_suffix);

    GenerateSecondTypeVars(oc, zc);
    BuildInstructionCore(params, suffix, zc);

    if ( zc == ZIC_VEC )
        Emit("z.SetType(n1->GetType());");
}

void ZAM_BinaryExprOpTemplate::GenerateSecondTypeVars(const OCVec& oc, ZAM_InstClass zc) {
    auto constant_op = oc[1] == ZAM_OC_CONSTANT;
    auto type_suffix = zc == ZIC_VEC ? "->Yield();" : ";";

    string type_src2;

    if ( zc == ZIC_COND ) {
        if ( oc[0] == ZAM_OC_CONSTANT )
            type_src2 = "n";
        else if ( oc[1] == ZAM_OC_CONSTANT )
            type_src2 = "c";
        else
            type_src2 = "n2";
    }
    else {
        if ( oc[1] == ZAM_OC_CONSTANT )
            type_src2 = "n2";
        else if ( oc[2] == ZAM_OC_CONSTANT )
            type_src2 = "c";
        else
            type_src2 = "n3";
    }

    Emit("const auto& t2 = " + type_src2 + "->GetType()" + type_suffix);
    Emit("auto tag2 = t2->Tag();");
    Emit("auto i_t2 = t2->InternalType();");
}

void ZAM_RelationalExprOpTemplate::Instantiate() {
    ZAM_BinaryExprOpTemplate::Instantiate();

    EmitTo(Cond);

    Emit("case EXPR_" + cname + ":");
    IndentUp();
    Emit("if ( n1 && n2 )");
    EmitUp("return " + cname + "VVb_cond(n1, n2);");
    Emit("else if ( n1 )");
    EmitUp("return " + cname + "VCb_cond(n1, c);");
    Emit("else");
    EmitUp("return " + cname + "CVb_cond(c, n2);");
    IndentDown();
    NL();
}

void ZAM_RelationalExprOpTemplate::BuildInstruction(const OCVec& oc, const string& params, const string& suffix,
                                                    ZAM_InstClass zc) {
    string op1;

    if ( zc == ZIC_COND ) {
        if ( oc[0] == ZAM_OC_CONSTANT )
            op1 = "c";
        else if ( oc[1] == ZAM_OC_CONSTANT )
            op1 = "n";
        else
            op1 = "n1";
    }
    else {
        if ( oc[1] == ZAM_OC_CONSTANT )
            op1 = "c";
        else
            op1 = "n2";
    }

    auto type_suffix = zc == ZIC_VEC ? "->Yield();" : ";";
    Emit("const auto& t = " + op1 + "->GetType()" + type_suffix);
    GenerateSecondTypeVars(oc, zc);
    BuildInstructionCore(params, suffix, zc);

    if ( zc == ZIC_VEC )
        Emit("z.SetType(n1->GetType());");
}

void ZAM_InternalOpTemplate::Parse(const string& attr, const string& line, const Words& words) {
    if ( attr == "num-call-args" )
        ParseCall(line, words);

    else if ( attr == "indirect-call" || attr == "indirect-local-call" ) {
        if ( words.size() != 1 )
            g->Gripe("indirect-call takes one argument", line);

        // Note, currently only works with a *subsequent* num-call-args,
        // whose setting needs to be 'n'.
        is_indirect_call = true;

        if ( attr == "indirect-local-call" )
            is_local_indirect_call = true;
    }

    else
        ZAM_OpTemplate::Parse(attr, line, words);
}

void ZAM_InternalOpTemplate::ParseCall(const string& line, const Words& words) {
    if ( words.size() != 2 )
        g->Gripe("num-call-args takes one argument", line);

    eval = "std::vector<ValPtr> args;\n";

    auto& arg = words[1];
    int n = arg == "n" ? -1 : stoi(arg);

    auto arg_offset = HasAssignVal() ? 1 : 0;
    auto arg_slot = arg_offset + 1;

    string func = "Z_AUX->func";

    if ( n == 1 )
        eval += "args.push_back($1.ToVal(Z_TYPE));\n";

    else if ( n != 0 ) {
        eval += "auto aux = Z_AUX;\n";

        if ( n < 0 ) {
            if ( is_indirect_call ) {
                func = "func";

                if ( is_local_indirect_call )
                    eval += "auto func = $1.AsFunc();\n";
                else {
                    eval += "auto func_v = aux->id_val->GetVal();\n";
                    eval += "auto func = func_v ? func_v->AsFunc() : nullptr;\n";
                }

                eval += "if ( ! func )\n";
                eval += "\t{\n";
                eval += "\tZAM_run_time_error(Z_LOC, \"value used but not set\");\n";
                eval += "\tbreak;\n";
                eval += "\t}\n";
            }

            eval += "auto n = aux->n;\n";
            eval += "args.reserve(n);\n";
            eval += "for ( auto i = 0; i < n; ++i )\n";
            eval += "\targs.push_back(aux->ToVal(frame, i));\n";
        }

        else
            for ( auto i = 0; i < n; ++i ) {
                eval += "args.push_back(aux->ToVal(frame, ";
                eval += to_string(i);
                eval += "));\n";
            }
    }

    eval += "f->SetOnlyCall(Z_AUX->call_expr.get());\n";
    eval += "ZAM_PROFILE_PRE_CALL\n";

    if ( HasAssignVal() ) {
        const auto& av = GetAssignVal();
        eval += "auto " + av + " = " + func + "->Invoke(&args, f);\n";
        eval += "if ( ! " + av + " ) { ZAM_error = true; break; }\n";

        // Postpone the profiling follow-up until after we process
        // the assignment.
        post_eval = "ZAM_PROFILE_POST_CALL\n";
    }
    else {
        eval += "(void) " + func + "->Invoke(&args, f);\n";
        eval += "ZAM_PROFILE_POST_CALL\n";
    }
}

bool TemplateInput::ScanLine(string& line) {
    if ( ! put_back.empty() ) {
        line = put_back;
        put_back.clear();
        return true;
    }

    char buf[8192];

    // Read lines, discarding comments, which have to start at the
    // beginning of a line.
    do {
        if ( ! fgets(buf, sizeof buf, f) )
            return false;
        ++loc.line_num;
    } while ( buf[0] == '#' );

    line = buf;
    return true;
}

vector<string> TemplateInput::SplitIntoWords(const string& line) const {
    vector<string> words;

    for ( auto start = line.c_str(); *start && *start != '\n'; ) {
        auto end = start + 1;
        while ( *end && ! isspace(*end) )
            ++end;

        words.emplace_back(string(start, end - start));

        start = end;
        while ( *start && isspace(*start) )
            ++start;
    }

    return words;
}

string TemplateInput::SkipWords(const string& line, int n) const {
    auto s = line.c_str();

    for ( int i = 0; i < n; ++i ) {
        // Find end of current word.
        while ( *s && *s != '\n' ) {
            if ( isspace(*s) )
                break;
            ++s;
        }

        if ( *s == '\n' )
            break;

        // Find start of next word.
        while ( *s && isspace(*s) )
            ++s;
    }

    return string(s);
}

void TemplateInput::Gripe(const char* msg, const string& input) const {
    auto input_s = input.c_str();
    size_t n = strlen(input_s);

    fprintf(stderr, "%s, line %d: %s - %s", loc.file_name, loc.line_num, msg, input_s);
    if ( n == 0 || input_s[n - 1] != '\n' )
        fprintf(stderr, "\n");

    exit(1);
}

void TemplateInput::Gripe(const char* msg, const InputLoc& l) const {
    fprintf(stderr, "%s, line %d: %s\n", l.file_name, l.line_num, msg);
    exit(1);
}

ZAMGen::ZAMGen(int argc, char** argv) {
    auto prog_name = (argv++)[0];

    if ( --argc < 1 ) {
        fprintf(stderr, "usage: %s <ZAM-templates-file>\n", prog_name);
        exit(1);
    }

    while ( argc-- > 0 ) {
        auto file_name = (argv++)[0];
        bool is_stdin = file_name == std::string("-");
        auto f = is_stdin ? stdin : fopen(file_name, "r");

        if ( ! f ) {
            fprintf(stderr, "%s: cannot open \"%s\"\n", prog_name, file_name);
            exit(1);
        }

        ti = make_unique<TemplateInput>(f, prog_name, file_name);

        while ( ParseTemplate() )
            ;

        if ( ! is_stdin )
            fclose(f);
    }

    InitEmitTargets();

    for ( auto& t : templates )
        t->Instantiate();

    GenMacros();

    CloseEmitTargets();
}

void ZAMGen::ReadMacro(const string& line) {
    vector<string> mac;
    mac.emplace_back(SkipWords(line, 1));

    string s;
    while ( ScanLine(s) ) {
        if ( s.size() <= 1 || ! isspace(s.c_str()[0]) ) {
            PutBack(s);
            break;
        }

        if ( regex_search(s, regex("\\$[$123]")) )
            Gripe("macro has $-param", s);

        mac.push_back(s);
    }

    macros.emplace_back(std::move(mac));
}

void ZAMGen::GenMacros() {
    for ( auto& m : macros ) {
        for ( auto i = 0U; i < m.size(); ++i ) {
            auto ms = m[i];
            if ( i == 0 ) {
                auto name = regex_replace(ms, regex("[( ].*\n"), "");
                Emit(MacroDesc, "{ \"" + name + "\",");

                ms = "#define " + ms;
            }

            auto desc = ms;
            desc.erase(desc.find('\n'));
            desc = regex_replace(desc, regex("\\\\"), "\\\\");
            desc = regex_replace(desc, regex("\""), "\\\"");

            if ( i < m.size() - 1 ) {
                ms = regex_replace(ms, regex("\n"), " \\\n");
                desc.append(" \\\\\\n");
            }

            Emit(MacroDesc, "  \"" + desc + "\"");
            if ( i == m.size() - 1 )
                Emit(MacroDesc, "},");

            Emit(EvalMacros, ms);
        }

        Emit(EvalMacros, "\n");
    }
}

string ZAMGen::GenOpCode(const ZAM_OpTemplate* op_templ, const string& suffix, ZAM_InstClass zc) {
    auto op = "OP_" + op_templ->CanonicalName() + suffix;

    static unordered_set<string> known_opcodes;

    if ( known_opcodes.count(op) > 0 )
        // We've already done this one, don't re-define its auxiliary
        // information.
        return op;

    known_opcodes.insert(op);

    IndentUp();

    // Generate the enum defining the opcode ...
    Emit(OpDef, op + ",");

    // ... the "flavor" of how it treats its first operand ...
    auto op_comment = ",\t// " + op;
    auto op1_always_read = (zc == ZIC_FIELD || zc == ZIC_COND);
    auto flavor = op1_always_read ? "OP1_READ" : op_templ->GetOp1Flavor();
    Emit(Op1Flavor, flavor + op_comment);

    // ... whether it has side effects ...
    auto se = op_templ->HasSideEffects() ? "true" : "false";
    Emit(OpSideEffects, se + op_comment);

    // ... and the switch case that maps the enum to a string
    // representation.
    auto name = op_templ->BaseName();
    transform(name.begin(), name.end(), name.begin(), ::tolower);
    name += suffix;
    transform(name.begin(), name.end(), name.begin(), under_to_dash);
    Emit(OpName, "case " + op + ":\treturn \"" + name + "\";");

    IndentDown();

    return op;
}

void ZAMGen::Emit(EmitTarget et, const string& s) {
    assert(et != None);

    if ( gen_files.count(et) == 0 ) {
        fprintf(stderr, "bad generation file type\n");
        exit(1);
    }

    FILE* f = gen_files[et];

    for ( auto i = indent_level; i > 0; --i )
        fputc('\t', f);

    if ( string_lit ) {
        fputc('"', f);
        for ( auto sp = s.c_str(); *sp; ++sp ) {
            if ( *sp == '\\' )
                fputs("\\\\", f);
            else if ( *sp == '"' )
                fputs("\\\"", f);
            else if ( *sp == '\n' )
                fputs("\\n", f);
            else
                fputc(*sp, f);
        }
        fputc('"', f);
    }

    else
        fputs(s.c_str(), f);

    if ( ! no_NL && (s.empty() || s.back() != '\n') )
        fputc('\n', f);
}

void ZAMGen::InitEmitTargets() {
    // Maps an EmitTarget enum to its corresponding filename.
    static const unordered_map<EmitTarget, const char*> gen_file_names = {
        {None, nullptr},
        {AssignFlavor, "ZAM-AssignFlavorsDefs.h"},
        {C1Def, "ZAM-GenExprsDefsC1.h"},
        {C1FieldDef, "ZAM-GenFieldsDefsC1.h"},
        {C2Def, "ZAM-GenExprsDefsC2.h"},
        {C2FieldDef, "ZAM-GenFieldsDefsC2.h"},
        {C3Def, "ZAM-GenExprsDefsC3.h"},
        {Cond, "ZAM-Conds.h"},
        {DirectDef, "ZAM-DirectDefs.h"},
        {Eval, "ZAM-EvalDefs.h"},
        {EvalMacros, "ZAM-EvalMacros.h"},
        {MacroDesc, "ZAM-MacroDesc.h"},
        {MethodDecl, "ZAM-MethodDecls.h"},
        {MethodDef, "ZAM-MethodDefs.h"},
        {Op1Flavor, "ZAM-Op1FlavorsDefs.h"},
        {OpDef, "ZAM-OpsDefs.h"},
        {OpDesc, "ZAM-OpDesc.h"},
        {OpName, "ZAM-OpsNamesDefs.h"},
        {OpSideEffects, "ZAM-OpSideEffects.h"},
        {VDef, "ZAM-GenExprsDefsV.h"},
        {VFieldDef, "ZAM-GenFieldsDefsV.h"},
        {Vec1Eval, "ZAM-Vec1EvalDefs.h"},
        {Vec2Eval, "ZAM-Vec2EvalDefs.h"},
    };

    for ( auto& gfn : gen_file_names ) {
        auto fn = gfn.second;
        if ( ! fn )
            continue;

        auto f = fopen(fn, "w");
        if ( ! f ) {
            fprintf(stderr, "can't open generation file %s\n", fn);
            exit(1);
        }

        gen_files[gfn.first] = f;
    }

    // Avoid bugprone-branch-clone warnings from clang-tidy in generated code.
    Emit(OpName, "// NOLINTBEGIN(bugprone-branch-clone)");
    Emit(Eval, "// NOLINTBEGIN(bugprone-branch-clone)");
    Emit(EvalMacros, "// NOLINTBEGIN(bugprone-macro-parentheses)");
    Emit(EvalMacros, "// NOLINTBEGIN(cppcoreguidelines-macro-usage)");

    InitSwitch(C1Def, "C1 assignment");
    InitSwitch(C2Def, "C2 assignment");
    InitSwitch(C3Def, "C3 assignment");
    InitSwitch(VDef, "V assignment");

    InitSwitch(C1FieldDef, "C1 field assignment");
    InitSwitch(C2FieldDef, "C2 field assignment");
    InitSwitch(VFieldDef, "V field assignment");
}

void ZAMGen::InitSwitch(EmitTarget et, string desc) {
    Emit(et, "{");
    Emit(et, "switch ( rhs->Tag() ) {");

    switch_targets[et] = std::move(desc);
}

void ZAMGen::CloseEmitTargets() {
    FinishSwitches();

    Emit(OpName, "// NOLINTEND(bugprone-branch-clone)");
    Emit(Eval, "// NOLINTEND(bugprone-branch-clone)");
    Emit(EvalMacros, "// NOLINTEND(cppcoreguidelines-macro-usage)");
    Emit(EvalMacros, "// NOLINTEND(bugprone-macro-parentheses)");

    for ( auto& gf : gen_files )
        fclose(gf.second);
}

void ZAMGen::FinishSwitches() {
    for ( auto& st : switch_targets ) {
        auto et = st.first;
        auto& desc = st.second;

        Emit(et, "default:");
        IndentUp();
        Emit(et, "reporter->InternalError(\"inconsistency in " + desc + ": %s\", obj_desc(rhs).c_str());");
        IndentDown();
        Emit(et, "}");
        Emit(et, "}");
    }
}

bool ZAMGen::ParseTemplate() {
    string line;

    if ( ! ScanLine(line) )
        return false;

    if ( line.size() <= 1 )
        // A blank line - no template to parse.
        return true;

    auto words = SplitIntoWords(line);

    if ( words.size() < 2 )
        Gripe("too few words at start of template", line);

    const auto& op = words[0];

    if ( op == "macro" ) {
        ReadMacro(line);
        return true;
    }

    const auto& op_name = words[1];

    // We track issues with the wrong number of template arguments
    // up front, to avoid misinvoking constructors, but we don't
    // report these until later because if the template names a
    // bad operation, it's better to report that as the core problem.
    const char* args_mismatch = nullptr;

    if ( op == "direct-unary-op" ) {
        if ( words.size() != 3 )
            args_mismatch = "direct-unary-op takes 2 arguments";
    }

    else if ( words.size() != 2 )
        args_mismatch = "templates take 1 argument";

    unique_ptr<ZAM_OpTemplate> t;

    if ( op == "op" )
        t = make_unique<ZAM_OpTemplate>(this, op_name);
    else if ( op == "unary-op" )
        t = make_unique<ZAM_UnaryOpTemplate>(this, op_name);
    else if ( op == "direct-unary-op" && ! args_mismatch )
        t = make_unique<ZAM_DirectUnaryOpTemplate>(this, op_name, words[2]);
    else if ( op == "assign-op" )
        t = make_unique<ZAM_AssignOpTemplate>(this, op_name);
    else if ( op == "expr-op" )
        t = make_unique<ZAM_ExprOpTemplate>(this, op_name);
    else if ( op == "unary-expr-op" )
        t = make_unique<ZAM_UnaryExprOpTemplate>(this, op_name);
    else if ( op == "binary-expr-op" )
        t = make_unique<ZAM_BinaryExprOpTemplate>(this, op_name);
    else if ( op == "rel-expr-op" )
        t = make_unique<ZAM_RelationalExprOpTemplate>(this, op_name);
    else if ( op == "internal-op" )
        t = make_unique<ZAM_InternalOpTemplate>(this, op_name);
    else if ( op == "predicate-op" ) {
        t = make_unique<ZAM_InternalOpTemplate>(this, op_name);
        t->SetIsPredicate();
    }
    else if ( op == "internal-assignment-op" )
        t = make_unique<ZAM_InternalAssignOpTemplate>(this, op_name);

    else
        Gripe("bad template name", op);

    if ( args_mismatch )
        Gripe(args_mismatch, line);

    t->Build();
    templates.emplace_back(std::move(t));

    return true;
}

int main(int argc, char** argv) {
    try {
        ZAMGen zg(argc, argv);
        exit(0);
    } catch ( const std::regex_error& e ) {
        fprintf(stderr, "%s: regular expression error - %s\n", argv[0], e.what());
        exit(1);
    }
}
