dlls/jscript/function.c

/*
 * Copyright 2008 Jacek Caban for CodeWeavers
 *
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 2.1 of the License, or (at your option) any later version.
 *
 * This library is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with this library; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301, USA
 */

#include "jscript.h"
#include "engine.h"

#include "wine/debug.h"

WINE_DEFAULT_DEBUG_CHANNEL(jscript);

typedef struct {
    DispatchEx dispex;
    builtin_invoke_t value_proc;
    const WCHAR *name;
    DWORD flags;
    source_elements_t *source;
    parameter_t *parameters;
    scope_chain_t *scope_chain;
    parser_ctx_t *parser;
    const WCHAR *src_str;
    DWORD src_len;
    DWORD length;
} FunctionInstance;

static inline FunctionInstance *function_from_vdisp(vdisp_t *vdisp)
{
    return (FunctionInstance*)vdisp->u.jsdisp;
}

static inline FunctionInstance *function_this(vdisp_t *jsthis)
{
    return is_vclass(jsthis, JSCLASS_FUNCTION) ? function_from_vdisp(jsthis) : NULL;
}

static const WCHAR prototypeW[] = {'p','r','o','t','o','t', 'y', 'p','e',0};

static const WCHAR lengthW[] = {'l','e','n','g','t','h',0};
static const WCHAR toStringW[] = {'t','o','S','t','r','i','n','g',0};
static const WCHAR applyW[] = {'a','p','p','l','y',0};
static const WCHAR callW[] = {'c','a','l','l',0};

static IDispatch *get_this(DISPPARAMS *dp)
{
    DWORD i;

    for(i=0; i < dp->cNamedArgs; i++) {
        if(dp->rgdispidNamedArgs[i] == DISPID_THIS) {
            if(V_VT(dp->rgvarg+i) == VT_DISPATCH)
                return V_DISPATCH(dp->rgvarg+i);

            WARN("This is not VT_DISPATCH\n");
            return NULL;
        }
    }

    TRACE("no this passed\n");
    return NULL;
}

static HRESULT init_parameters(DispatchEx *var_disp, FunctionInstance *function, DISPPARAMS *dp,
        jsexcept_t *ei, IServiceProvider *caller)
{
    parameter_t *param;
    VARIANT var_empty;
    DWORD cargs, i=0;
    HRESULT hres;

    V_VT(&var_empty) = VT_EMPTY;
    cargs = arg_cnt(dp);

    for(param = function->parameters; param; param = param->next) {
        hres = jsdisp_propput_name(var_disp, param->identifier,
                i < cargs ? get_arg(dp,i) : &var_empty, ei, caller);
        if(FAILED(hres))
            return hres;

        i++;
    }

    return S_OK;
}

static HRESULT Arguments_value(script_ctx_t *ctx, vdisp_t *jsthis, WORD flags, DISPPARAMS *dp,
        VARIANT *retv, jsexcept_t *ei, IServiceProvider *caller)
{
    FIXME("\n");
    return E_NOTIMPL;
}

static const builtin_info_t Arguments_info = {
    JSCLASS_ARGUMENTS,
    {NULL, Arguments_value, 0},
    0, NULL,
    NULL,
    NULL
};

static HRESULT create_arguments(script_ctx_t *ctx, IDispatch *calee, DISPPARAMS *dp,
        jsexcept_t *ei, IServiceProvider *caller, DispatchEx **ret)
{
    DispatchEx *args;
    VARIANT var;
    DWORD i;
    HRESULT hres;

    static const WCHAR caleeW[] = {'c','a','l','l','e','e',0};

    args = heap_alloc_zero(sizeof(DispatchEx));
    if(!args)
        return E_OUTOFMEMORY;

    hres = init_dispex_from_constr(args, ctx, &Arguments_info, ctx->object_constr);
    if(FAILED(hres)) {
        heap_free(args);
        return hres;
    }

    for(i=0; i < arg_cnt(dp); i++) {
        hres = jsdisp_propput_idx(args, i, get_arg(dp,i), ei, caller);
        if(FAILED(hres))
            break;
    }

    if(SUCCEEDED(hres)) {
        V_VT(&var) = VT_I4;
        V_I4(&var) = arg_cnt(dp);
        hres = jsdisp_propput_name(args, lengthW, &var, ei, caller);

        if(SUCCEEDED(hres)) {
            V_VT(&var) = VT_DISPATCH;
            V_DISPATCH(&var) = calee;
            hres = jsdisp_propput_name(args, caleeW, &var, ei, caller);
        }
    }

    if(FAILED(hres)) {
        jsdisp_release(args);
        return hres;
    }

    *ret = args;
    return S_OK;
}

static HRESULT create_var_disp(script_ctx_t *ctx, FunctionInstance *function, DISPPARAMS *dp, jsexcept_t *ei,
                               IServiceProvider *caller, DispatchEx **ret)
{
    DispatchEx *var_disp, *arg_disp;
    HRESULT hres;

    static const WCHAR argumentsW[] = {'a','r','g','u','m','e','n','t','s',0};

    hres = create_dispex(ctx, NULL, NULL, &var_disp);
    if(FAILED(hres))
        return hres;

    hres = create_arguments(ctx, (IDispatch*)_IDispatchEx_(&function->dispex),
            dp, ei, caller, &arg_disp);
    if(SUCCEEDED(hres)) {
        VARIANT var;

        V_VT(&var) = VT_DISPATCH;
        V_DISPATCH(&var) = (IDispatch*)_IDispatchEx_(arg_disp);
        hres = jsdisp_propput_name(var_disp, argumentsW, &var, ei, caller);
        jsdisp_release(arg_disp);
    }

    if(SUCCEEDED(hres))
        hres = init_parameters(var_disp, function, dp, ei, caller);
    if(FAILED(hres)) {
        jsdisp_release(var_disp);
        return hres;
    }

    *ret = var_disp;
    return S_OK;
}

static HRESULT invoke_source(script_ctx_t *ctx, FunctionInstance *function, IDispatch *this_obj, DISPPARAMS *dp,
        VARIANT *retv, jsexcept_t *ei, IServiceProvider *caller)
{
    DispatchEx *var_disp;
    exec_ctx_t *exec_ctx;
    scope_chain_t *scope;
    HRESULT hres;

    if(!function->source) {
        FIXME("no source\n");
        return E_FAIL;
    }

    hres = create_var_disp(ctx, function, dp, ei, caller, &var_disp);
    if(FAILED(hres))
        return hres;

    hres = scope_push(function->scope_chain, var_disp, &scope);
    if(SUCCEEDED(hres)) {
        hres = create_exec_ctx(ctx, this_obj, var_disp, scope, &exec_ctx);
        scope_release(scope);
    }
    jsdisp_release(var_disp);
    if(FAILED(hres))
        return hres;

    hres = exec_source(exec_ctx, function->parser, function->source, EXECT_FUNCTION, ei, retv);
    exec_release(exec_ctx);

    return hres;
}

static HRESULT invoke_constructor(script_ctx_t *ctx, FunctionInstance *function, DISPPARAMS *dp,
        VARIANT *retv, jsexcept_t *ei, IServiceProvider *caller)
{
    DispatchEx *this_obj;
    VARIANT var;
    HRESULT hres;

    hres = create_object(ctx, &function->dispex, &this_obj);
    if(FAILED(hres))
        return hres;

    hres = invoke_source(ctx, function, (IDispatch*)_IDispatchEx_(this_obj), dp, &var, ei, caller);
    if(FAILED(hres)) {
        jsdisp_release(this_obj);
        return hres;
    }

    V_VT(retv) = VT_DISPATCH;
    if(V_VT(&var) == VT_DISPATCH) {
        jsdisp_release(this_obj);
        V_DISPATCH(retv) = V_DISPATCH(&var);
    }else {
        VariantClear(&var);
        V_DISPATCH(retv) = (IDispatch*)_IDispatchEx_(this_obj);
    }
    return S_OK;
}

static HRESULT invoke_value_proc(script_ctx_t *ctx, FunctionInstance *function, IDispatch *this_disp, WORD flags, DISPPARAMS *dp,
        VARIANT *retv, jsexcept_t *ei, IServiceProvider *caller)
{
    vdisp_t vthis;
    HRESULT hres;

    if(this_disp)
        set_disp(&vthis, this_disp);
    else if(ctx->host_global)
        set_disp(&vthis, ctx->host_global);
    else
        set_jsdisp(&vthis, ctx->global);

    hres = function->value_proc(ctx, &vthis, flags, dp, retv, ei, caller);

    vdisp_release(&vthis);
    return hres;
}

static HRESULT call_function(script_ctx_t *ctx, FunctionInstance *function, IDispatch *this_obj, DISPPARAMS *args,
        VARIANT *retv, jsexcept_t *ei, IServiceProvider *caller)
{
    if(function->value_proc)
        return invoke_value_proc(ctx, function, this_obj, DISPATCH_METHOD, args, retv, ei, caller);

    return invoke_source(ctx, function, this_obj, args, retv, ei, caller);
}

static HRESULT function_to_string(FunctionInstance *function, BSTR *ret)
{
    BSTR str;

    static const WCHAR native_prefixW[] = {'\n','f','u','n','c','t','i','o','n',' '};
    static const WCHAR native_suffixW[] =
        {'(',')',' ','{','\n',' ',' ',' ',' ','[','n','a','t','i','v','e',' ','c','o','d','e',']','\n','}','\n'};

    if(function->value_proc) {
        DWORD name_len;

        name_len = strlenW(function->name);
        str = SysAllocStringLen(NULL, sizeof(native_prefixW) + name_len*sizeof(WCHAR) + sizeof(native_suffixW));
        if(!str)
            return E_OUTOFMEMORY;

        memcpy(str, native_prefixW, sizeof(native_prefixW));
        memcpy(str + sizeof(native_prefixW)/sizeof(WCHAR), function->name, name_len*sizeof(WCHAR));
        memcpy(str + sizeof(native_prefixW)/sizeof(WCHAR) + name_len, native_suffixW, sizeof(native_suffixW));
    }else {
        str = SysAllocStringLen(function->src_str, function->src_len);
        if(!str)
            return E_OUTOFMEMORY;
    }

    *ret = str;
    return S_OK;
}

static HRESULT Function_length(script_ctx_t *ctx, vdisp_t *jsthis, WORD flags, DISPPARAMS *dp,
        VARIANT *retv, jsexcept_t *ei, IServiceProvider *sp)
{
    FunctionInstance *This = function_from_vdisp(jsthis);

    TRACE("%p %d\n", This, This->length);

    switch(flags) {
    case DISPATCH_PROPERTYGET:
        V_VT(retv) = VT_I4;
        V_I4(retv) = This->length;
        break;
    default:
        FIXME("unimplemented flags %x\n", flags);
        return E_NOTIMPL;
    }

    return S_OK;
}

static HRESULT Function_toString(script_ctx_t *ctx, vdisp_t *jsthis, WORD flags, DISPPARAMS *dp,
        VARIANT *retv, jsexcept_t *ei, IServiceProvider *sp)
{
    FunctionInstance *function;
    BSTR str;
    HRESULT hres;

    TRACE("\n");

    if(!(function = function_this(jsthis)))
        return throw_type_error(ctx, ei, IDS_NOT_FUNC, NULL);

    hres = function_to_string(function, &str);
    if(FAILED(hres))
        return hres;

    if(retv) {
        V_VT(retv) = VT_BSTR;
        V_BSTR(retv) = str;
    }else {
        SysFreeString(str);
    }
    return S_OK;
}

static HRESULT array_to_args(script_ctx_t *ctx, DispatchEx *arg_array, jsexcept_t *ei, IServiceProvider *caller,
        DISPPARAMS *args)
{
    VARIANT var, *argv;
    DWORD length, i;
    HRESULT hres;

    hres = jsdisp_propget_name(arg_array, lengthW, &var, ei, NULL/*FIXME*/);
    if(FAILED(hres))
        return hres;

    hres = to_uint32(ctx, &var, ei, &length);
    VariantClear(&var);
    if(FAILED(hres))
        return hres;

    argv = heap_alloc(length * sizeof(VARIANT));
    if(!argv)
        return E_OUTOFMEMORY;

    for(i=0; i<length; i++) {
        hres = jsdisp_get_idx(arg_array, i, argv+i, ei, caller);
        if(hres == DISP_E_UNKNOWNNAME)
            V_VT(argv+i) = VT_EMPTY;
        else if(FAILED(hres)) {
            while(i--)
                VariantClear(argv+i);
            heap_free(argv);
            return hres;
        }
    }

    args->cArgs = length;
    args->rgvarg = argv;
    return S_OK;
}

static HRESULT Function_apply(script_ctx_t *ctx, vdisp_t *jsthis, WORD flags, DISPPARAMS *dp,
        VARIANT *retv, jsexcept_t *ei, IServiceProvider *caller)
{
    FunctionInstance *function;
    DISPPARAMS args = {NULL,NULL,0,0};
    DWORD argc, i;
    IDispatch *this_obj = NULL;
    HRESULT hres = S_OK;

    TRACE("\n");

    if(!(function = function_this(jsthis)))
        return throw_type_error(ctx, ei, IDS_NOT_FUNC, NULL);

    argc = arg_cnt(dp);
    if(argc) {
        VARIANT *v = get_arg(dp,0);

        if(V_VT(v) != VT_EMPTY && V_VT(v) != VT_NULL) {
            hres = to_object(ctx, v, &this_obj);
            if(FAILED(hres))
                return hres;
        }
    }

    if(argc >= 2) {
        DispatchEx *arg_array = NULL;

        if(V_VT(get_arg(dp,1)) == VT_DISPATCH) {
            arg_array = iface_to_jsdisp((IUnknown*)V_DISPATCH(get_arg(dp,1)));
            if(arg_array &&
               (!is_class(arg_array, JSCLASS_ARRAY) && !is_class(arg_array, JSCLASS_ARGUMENTS) )) {
                jsdisp_release(arg_array);
                arg_array = NULL;
            }
        }

        if(arg_array) {
            hres = array_to_args(ctx, arg_array, ei, caller, &args);
            jsdisp_release(arg_array);
        }else {
            FIXME("throw TypeError\n");
            hres = E_FAIL;
        }
    }

    hres = call_function(ctx, function, this_obj, &args, retv, ei, caller);

    if(this_obj)
        IDispatch_Release(this_obj);
    for(i=0; i<args.cArgs; i++)
        VariantClear(args.rgvarg+i);
    heap_free(args.rgvarg);
    return hres;
}

static HRESULT Function_call(script_ctx_t *ctx, vdisp_t *jsthis, WORD flags, DISPPARAMS *dp,
        VARIANT *retv, jsexcept_t *ei, IServiceProvider *caller)
{
    FunctionInstance *function;
    DISPPARAMS args = {NULL,NULL,0,0};
    IDispatch *this_obj = NULL;
    DWORD argc;
    HRESULT hres;

    TRACE("\n");

    if(!(function = function_this(jsthis)))
        return throw_type_error(ctx, ei, IDS_NOT_FUNC, NULL);

    argc = arg_cnt(dp);
    if(argc) {
        VARIANT *v = get_arg(dp,0);

        if(V_VT(v) != VT_EMPTY && V_VT(v) != VT_NULL) {
            hres = to_object(ctx, v, &this_obj);
            if(FAILED(hres))
                return hres;
        }

        args.cArgs = argc-1;
    }

    if(args.cArgs)
        args.rgvarg = dp->rgvarg + dp->cArgs - args.cArgs-1;

    hres = call_function(ctx, function, this_obj, &args, retv, ei, caller);

    if(this_obj)
        IDispatch_Release(this_obj);
    return hres;
}

HRESULT Function_value(script_ctx_t *ctx, vdisp_t *jsthis, WORD flags, DISPPARAMS *dp,
        VARIANT *retv, jsexcept_t *ei, IServiceProvider *caller)
{
    FunctionInstance *function;

    TRACE("\n");

    if(!is_vclass(jsthis, JSCLASS_FUNCTION)) {
        ERR("dispex is not a function\n");
        return E_FAIL;
    }

    function = (FunctionInstance*)jsthis->u.jsdisp;

    switch(flags) {
    case DISPATCH_METHOD:
        if(function->value_proc)
            return invoke_value_proc(ctx, function, get_this(dp), flags, dp, retv, ei, caller);

        return invoke_source(ctx, function, get_this(dp), dp, retv, ei, caller);

    case DISPATCH_PROPERTYGET: {
        HRESULT hres;
        BSTR str;

        hres = function_to_string(function, &str);
        if(FAILED(hres))
            return hres;

        V_VT(retv) = VT_BSTR;
        V_BSTR(retv) = str;
        break;
    }

    case DISPATCH_CONSTRUCT:
        if(function->value_proc)
            return invoke_value_proc(ctx, function, get_this(dp), flags, dp, retv, ei, caller);

        return invoke_constructor(ctx, function, dp, retv, ei, caller);

    default:
        FIXME("not implemented flags %x\n", flags);
        return E_NOTIMPL;
    }

    return S_OK;
}

static void Function_destructor(DispatchEx *dispex)
{
    FunctionInstance *This = (FunctionInstance*)dispex;

    if(This->parser)
        parser_release(This->parser);
    if(This->scope_chain)
        scope_release(This->scope_chain);
    heap_free(This);
}

static const builtin_prop_t Function_props[] = {
    {applyW,                 Function_apply,                 PROPF_METHOD|2},
    {callW,                  Function_call,                  PROPF_METHOD|1},
    {lengthW,                Function_length,                0},
    {toStringW,              Function_toString,              PROPF_METHOD}
};

static const builtin_info_t Function_info = {
    JSCLASS_FUNCTION,
    {NULL, Function_value, 0},
    sizeof(Function_props)/sizeof(*Function_props),
    Function_props,
    Function_destructor,
    NULL
};

static HRESULT create_function(script_ctx_t *ctx, const builtin_info_t *builtin_info, DWORD flags,
        BOOL funcprot, DispatchEx *prototype, FunctionInstance **ret)
{
    FunctionInstance *function;
    HRESULT hres;

    function = heap_alloc_zero(sizeof(FunctionInstance));
    if(!function)
        return E_OUTOFMEMORY;

    if(funcprot)
        hres = init_dispex(&function->dispex, ctx, &Function_info, prototype);
    else if(builtin_info)
        hres = init_dispex_from_constr(&function->dispex, ctx, builtin_info, ctx->function_constr);
    else
        hres = init_dispex_from_constr(&function->dispex, ctx, &Function_info, ctx->function_constr);
    if(FAILED(hres))
        return hres;

    function->flags = flags;
    function->length = flags & PROPF_ARGMASK;

    *ret = function;
    return S_OK;
}

static HRESULT set_prototype(script_ctx_t *ctx, DispatchEx *dispex, DispatchEx *prototype)
{
    jsexcept_t jsexcept;
    VARIANT var;

    V_VT(&var) = VT_DISPATCH;
    V_DISPATCH(&var) = (IDispatch*)_IDispatchEx_(prototype);
    memset(&jsexcept, 0, sizeof(jsexcept));

    return jsdisp_propput_name(dispex, prototypeW, &var, &jsexcept, NULL/*FIXME*/);
}

HRESULT create_builtin_function(script_ctx_t *ctx, builtin_invoke_t value_proc, const WCHAR *name,
        const builtin_info_t *builtin_info, DWORD flags, DispatchEx *prototype, DispatchEx **ret)
{
    FunctionInstance *function;
    HRESULT hres;

    hres = create_function(ctx, builtin_info, flags, FALSE, NULL, &function);
    if(FAILED(hres))
        return hres;

    hres = set_prototype(ctx, &function->dispex, prototype);
    if(FAILED(hres)) {
        jsdisp_release(&function->dispex);
        return hres;
    }

    function->value_proc = value_proc;
    function->name = name;

    *ret = &function->dispex;
    return S_OK;
}

HRESULT create_source_function(parser_ctx_t *ctx, parameter_t *parameters, source_elements_t *source,
        scope_chain_t *scope_chain, const WCHAR *src_str, DWORD src_len, DispatchEx **ret)
{
    FunctionInstance *function;
    DispatchEx *prototype;
    parameter_t *iter;
    DWORD length = 0;
    HRESULT hres;

    hres = create_object(ctx->script, NULL, &prototype);
    if(FAILED(hres))
        return hres;

    hres = create_function(ctx->script, NULL, PROPF_CONSTR, FALSE, NULL, &function);
    if(SUCCEEDED(hres)) {
        hres = set_prototype(ctx->script, &function->dispex, prototype);
        if(FAILED(hres))
            jsdisp_release(&function->dispex);
    }
    jsdisp_release(prototype);
    if(FAILED(hres))
        return hres;

    function->source = source;
    function->parameters = parameters;

    if(scope_chain) {
        scope_addref(scope_chain);
        function->scope_chain = scope_chain;
    }

    parser_addref(ctx);
    function->parser = ctx;

    for(iter = parameters; iter; iter = iter->next)
        length++;
    function->length = length;

    function->src_str = src_str;
    function->src_len = src_len;

    *ret = &function->dispex;
    return S_OK;
}

static HRESULT construct_function(script_ctx_t *ctx, DISPPARAMS *dp, jsexcept_t *ei, IDispatch **ret)
{
    function_expression_t *expr;
    WCHAR *str = NULL, *ptr;
    DWORD argc, len = 0, l;
    parser_ctx_t *parser;
    DispatchEx *function;
    BSTR *params = NULL;
    int i=0, j=0;
    HRESULT hres = S_OK;

    static const WCHAR function_anonymousW[] = {'f','u','n','c','t','i','o','n',' ','a','n','o','n','y','m','o','u','s','('};
    static const WCHAR function_beginW[] = {')',' ','{','\n'};
    static const WCHAR function_endW[] = {'\n','}',0};

    argc = arg_cnt(dp);
    if(argc) {
        params = heap_alloc(argc*sizeof(BSTR));
        if(!params)
            return E_OUTOFMEMORY;

        if(argc > 2)
            len = (argc-2)*2; /* separating commas */
        for(i=0; i < argc; i++) {
            hres = to_string(ctx, get_arg(dp,i), ei, params+i);
            if(FAILED(hres))
                break;
            len += SysStringLen(params[i]);
        }
    }

    if(SUCCEEDED(hres)) {
        len += (sizeof(function_anonymousW) + sizeof(function_beginW) + sizeof(function_endW)) / sizeof(WCHAR);
        str = heap_alloc(len*sizeof(WCHAR));
        if(str) {
            memcpy(str, function_anonymousW, sizeof(function_anonymousW));
            ptr = str + sizeof(function_anonymousW)/sizeof(WCHAR);
            if(argc > 1) {
                while(1) {
                    l = SysStringLen(params[j]);
                    memcpy(ptr, params[j], l*sizeof(WCHAR));
                    ptr += l;
                    if(++j == argc-1)
                        break;
                    *ptr++ = ',';
                    *ptr++ = ' ';
                }
            }
            memcpy(ptr, function_beginW, sizeof(function_beginW));
            ptr += sizeof(function_beginW)/sizeof(WCHAR);
            if(argc) {
                l = SysStringLen(params[argc-1]);
                memcpy(ptr, params[argc-1], l*sizeof(WCHAR));
                ptr += l;
            }
            memcpy(ptr, function_endW, sizeof(function_endW));

            TRACE("%s\n", debugstr_w(str));
        }else {
            hres = E_OUTOFMEMORY;
        }
    }

    while(--i >= 0)
        SysFreeString(params[i]);
    heap_free(params);
    if(FAILED(hres))
        return hres;

    hres = script_parse(ctx, str, NULL, &parser);
    heap_free(str);
    if(FAILED(hres))
        return hres;

    if(!parser->source || !parser->source->functions || parser->source->functions->next || parser->source->variables) {
        ERR("Invalid parser result!\n");
        parser_release(parser);
        return E_UNEXPECTED;
    }
    expr = parser->source->functions->expr;

    hres = create_source_function(parser, expr->parameter_list, expr->source_elements, NULL, expr->src_str,
            expr->src_len, &function);
    parser_release(parser);
    if(FAILED(hres))
        return hres;

    *ret = (IDispatch*)_IDispatchEx_(function);
    return S_OK;
}

static HRESULT FunctionConstr_value(script_ctx_t *ctx, vdisp_t *jsthis, WORD flags, DISPPARAMS *dp,
        VARIANT *retv, jsexcept_t *ei, IServiceProvider *sp)
{
    HRESULT hres;

    TRACE("\n");

    switch(flags) {
    case DISPATCH_CONSTRUCT: {
        IDispatch *ret;

        hres = construct_function(ctx, dp, ei, &ret);
        if(FAILED(hres))
            return hres;

        V_VT(retv) = VT_DISPATCH;
        V_DISPATCH(retv) = ret;
        break;
    }
    default:
        FIXME("unimplemented flags %x\n", flags);
        return E_NOTIMPL;
    }

    return S_OK;
}

static HRESULT FunctionProt_value(script_ctx_t *ctx, vdisp_t *jsthis, WORD flags, DISPPARAMS *dp,
        VARIANT *retv, jsexcept_t *ei, IServiceProvider *sp)
{
    FIXME("\n");
    return E_NOTIMPL;
}

HRESULT init_function_constr(script_ctx_t *ctx, DispatchEx *object_prototype)
{
    FunctionInstance *prot, *constr;
    HRESULT hres;

    static const WCHAR FunctionW[] = {'F','u','n','c','t','i','o','n',0};

    hres = create_function(ctx, NULL, PROPF_CONSTR, TRUE, object_prototype, &prot);
    if(FAILED(hres))
        return hres;

    prot->value_proc = FunctionProt_value;
    prot->name = prototypeW;

    hres = create_function(ctx, NULL, PROPF_CONSTR|1, TRUE, &prot->dispex, &constr);
    if(SUCCEEDED(hres)) {
        constr->value_proc = FunctionConstr_value;
        constr->name = FunctionW;
        hres = set_prototype(ctx, &constr->dispex, &prot->dispex);
        if(FAILED(hres))
            jsdisp_release(&constr->dispex);
    }
    jsdisp_release(&prot->dispex);
    if(FAILED(hres))
        return hres;

    ctx->function_constr = &constr->dispex;
    return S_OK;
}