source: mainline/uspace/app/sbi/src/run_expr.c@ 4204ad9

/*
 * Copyright (c) 2010 Jiri Svoboda
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 * - Redistributions of source code must retain the above copyright
 *   notice, this list of conditions and the following disclaimer.
 * - Redistributions in binary form must reproduce the above copyright
 *   notice, this list of conditions and the following disclaimer in the
 *   documentation and/or other materials provided with the distribution.
 * - The name of the author may not be used to endorse or promote products
 *   derived from this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

/** @file Runner (executes the code). */

#include <stdio.h>
#include <stdlib.h>
#include <assert.h>
#include "debug.h"
#include "intmap.h"
#include "list.h"
#include "mytypes.h"
#include "os/os.h"
#include "rdata.h"
#include "run.h"
#include "run_texpr.h"
#include "symbol.h"
#include "stree.h"
#include "strtab.h"
#include "tdata.h"

#include "run_expr.h"

static void run_nameref(run_t *run, stree_nameref_t *nameref,
    rdata_item_t **res);

static void run_literal(run_t *run, stree_literal_t *literal,
    rdata_item_t **res);
static void run_lit_int(run_t *run, stree_lit_int_t *lit_int,
    rdata_item_t **res);
static void run_lit_ref(run_t *run, stree_lit_ref_t *lit_ref,
    rdata_item_t **res);
static void run_lit_string(run_t *run, stree_lit_string_t *lit_string,
    rdata_item_t **res);

static void run_self_ref(run_t *run, stree_self_ref_t *self_ref,
    rdata_item_t **res);

static void run_binop(run_t *run, stree_binop_t *binop, rdata_item_t **res);
static void run_binop_int(run_t *run, stree_binop_t *binop, rdata_value_t *v1,
    rdata_value_t *v2, rdata_item_t **res);
static void run_binop_string(run_t *run, stree_binop_t *binop, rdata_value_t *v1,
    rdata_value_t *v2, rdata_item_t **res);
static void run_binop_ref(run_t *run, stree_binop_t *binop, rdata_value_t *v1,
    rdata_value_t *v2, rdata_item_t **res);

static void run_unop(run_t *run, stree_unop_t *unop, rdata_item_t **res);
static void run_new(run_t *run, stree_new_t *new_op, rdata_item_t **res);
static void run_new_array(run_t *run, stree_new_t *new_op,
    tdata_item_t *titem, rdata_item_t **res);
static void run_new_object(run_t *run, stree_new_t *new_op,
    tdata_item_t *titem, rdata_item_t **res);

static void run_access(run_t *run, stree_access_t *access, rdata_item_t **res);
static void run_access_item(run_t *run, stree_access_t *access,
    rdata_item_t *arg, rdata_item_t **res);
static void run_access_ref(run_t *run, stree_access_t *access,
    rdata_item_t *arg, rdata_item_t **res);
static void run_access_deleg(run_t *run, stree_access_t *access,
    rdata_item_t *arg, rdata_item_t **res);
static void run_access_object(run_t *run, stree_access_t *access,
    rdata_item_t *arg, rdata_item_t **res);

static void run_call(run_t *run, stree_call_t *call, rdata_item_t **res);
static void run_index(run_t *run, stree_index_t *index, rdata_item_t **res);
static void run_index_array(run_t *run, stree_index_t *index,
    rdata_item_t *base, list_t *args, rdata_item_t **res);
static void run_index_object(run_t *run, stree_index_t *index,
    rdata_item_t *base, list_t *args, rdata_item_t **res);
static void run_index_string(run_t *run, stree_index_t *index,
    rdata_item_t *base, list_t *args, rdata_item_t **res);
static void run_assign(run_t *run, stree_assign_t *assign, rdata_item_t **res);
static void run_as(run_t *run, stree_as_t *as_op, rdata_item_t **res);

/** Evaluate expression. */
void run_expr(run_t *run, stree_expr_t *expr, rdata_item_t **res)
{
#ifdef DEBUG_RUN_TRACE
        printf("Executing expression.\n");
#endif

        switch (expr->ec) {
        case ec_nameref:
                run_nameref(run, expr->u.nameref, res);
                break;
        case ec_literal:
                run_literal(run, expr->u.literal, res);
                break;
        case ec_self_ref:
                run_self_ref(run, expr->u.self_ref, res);
                break;
        case ec_binop:
                run_binop(run, expr->u.binop, res);
                break;
        case ec_unop:
                run_unop(run, expr->u.unop, res);
                break;
        case ec_new:
                run_new(run, expr->u.new_op, res);
                break;
        case ec_access:
                run_access(run, expr->u.access, res);
                break;
        case ec_call:
                run_call(run, expr->u.call, res);
                break;
        case ec_index:
                run_index(run, expr->u.index, res);
                break;
        case ec_assign:
                run_assign(run, expr->u.assign, res);
                break;
        case ec_as:
                run_as(run, expr->u.as_op, res);
                break;
        }

#ifdef DEBUG_RUN_TRACE
        printf("Expression result: ");
        rdata_item_print(*res);
        printf(".\n");
#endif
}

/** Evaluate name reference expression. */
static void run_nameref(run_t *run, stree_nameref_t *nameref,
    rdata_item_t **res)
{
        stree_symbol_t *sym;
        rdata_item_t *item;
        rdata_address_t *address;
        rdata_addr_var_t *addr_var;
        rdata_value_t *value;
        rdata_var_t *var;
        rdata_deleg_t *deleg_v;

        run_proc_ar_t *proc_ar;
        stree_symbol_t *csi_sym;
        stree_csi_t *csi;
        rdata_object_t *obj;
        rdata_var_t *member_var;

#ifdef DEBUG_RUN_TRACE
        printf("Run nameref.\n");
#endif

        /*
         * Look for a local variable.
         */
        var = run_local_vars_lookup(run, nameref->name->sid);
        if (var != NULL) {
                /* Found a local variable. */
                item = rdata_item_new(ic_address);
                address = rdata_address_new(ac_var);
                addr_var = rdata_addr_var_new();

                item->u.address = address;
                address->u.var_a = addr_var;
                addr_var->vref = var;

                *res = item;
#ifdef DEBUG_RUN_TRACE
                printf("Found local variable.\n");
#endif
                return;
        }

        /*
         * Look for a class-wide or global symbol.
         */

        /* Determine currently active object or CSI. */
        proc_ar = run_get_current_proc_ar(run);
        if (proc_ar->obj != NULL) {
                assert(proc_ar->obj->vc == vc_object);
                obj = proc_ar->obj->u.object_v;
                csi_sym = obj->class_sym;
                csi = symbol_to_csi(csi_sym);
                assert(csi != NULL);
        } else {
                csi = proc_ar->proc->outer_symbol->outer_csi;
                obj = NULL;
        }

        sym = symbol_lookup_in_csi(run->program, csi, nameref->name);

        switch (sym->sc) {
        case sc_csi:
#ifdef DEBUG_RUN_TRACE
                printf("Referencing class.\n");
#endif
                item = rdata_item_new(ic_value);
                value = rdata_value_new();
                var = rdata_var_new(vc_deleg);
                deleg_v = rdata_deleg_new();

                item->u.value = value;
                value->var = var;
                var->u.deleg_v = deleg_v;

                deleg_v->obj = NULL;
                deleg_v->sym = sym;
                *res = item;
                break;
        case sc_fun:
                /* There should be no global functions. */
                assert(csi != NULL);

                if (sym->outer_csi != csi) {
                        /* Function is not in the current object. */
                        printf("Error: Cannot access non-static member "
                            "function '");
                        symbol_print_fqn(sym);
                        printf("' from nested CSI '");
                        symbol_print_fqn(csi_sym);
                        printf("'.\n");
                        exit(1);
                }

                /* Construct delegate. */
                item = rdata_item_new(ic_value);
                value = rdata_value_new();
                item->u.value = value;

                var = rdata_var_new(vc_deleg);
                deleg_v = rdata_deleg_new();
                value->var = var;
                var->u.deleg_v = deleg_v;

                deleg_v->obj = proc_ar->obj;
                deleg_v->sym = sym;

                *res = item;
                break;
        case sc_var:
#ifdef DEBUG_RUN_TRACE
                printf("Referencing member variable.\n");
#endif
                /* There should be no global variables. */
                assert(csi != NULL);

                /* XXX Assume variable is not static for now. */
                assert(obj != NULL);

                if (sym->outer_csi != csi) {
                        /* Variable is not in the current object. */
                        printf("Error: Cannot access non-static member "
                            "variable '");
                        symbol_print_fqn(sym);
                        printf("' from nested CSI '");
                        symbol_print_fqn(csi_sym);
                        printf("'.\n");
                        exit(1);
                }

                /* Find member variable in object. */
                member_var = intmap_get(&obj->fields, nameref->name->sid);
                assert(member_var != NULL);

                /* Return address of the variable. */
                item = rdata_item_new(ic_address);
                address = rdata_address_new(ac_var);
                addr_var = rdata_addr_var_new();

                item->u.address = address;
                address->u.var_a = addr_var;
                addr_var->vref = member_var;

                *res = item;
                break;
        default:
                printf("Referencing symbol class %d unimplemented.\n", sym->sc);
                *res = NULL;
                break;
        }
}

/** Evaluate literal. */
static void run_literal(run_t *run, stree_literal_t *literal,
    rdata_item_t **res)
{
#ifdef DEBUG_RUN_TRACE
        printf("Run literal.\n");
#endif

        switch (literal->ltc) {
        case ltc_int:
                run_lit_int(run, &literal->u.lit_int, res);
                break;
        case ltc_ref:
                run_lit_ref(run, &literal->u.lit_ref, res);
                break;
        case ltc_string:
                run_lit_string(run, &literal->u.lit_string, res);
                break;
        default:
                assert(b_false);
        }
}

/** Evaluate integer literal. */
static void run_lit_int(run_t *run, stree_lit_int_t *lit_int,
    rdata_item_t **res)
{
        rdata_item_t *item;
        rdata_value_t *value;
        rdata_var_t *var;
        rdata_int_t *int_v;

#ifdef DEBUG_RUN_TRACE
        printf("Run integer literal.\n");
#endif
        (void) run;

        item = rdata_item_new(ic_value);
        value = rdata_value_new();
        var = rdata_var_new(vc_int);
        int_v = rdata_int_new();

        item->u.value = value;
        value->var = var;
        var->u.int_v = int_v;
        int_v->value = lit_int->value;

        *res = item;
}

/** Evaluate reference literal (@c nil). */
static void run_lit_ref(run_t *run, stree_lit_ref_t *lit_ref,
    rdata_item_t **res)
{
        rdata_item_t *item;
        rdata_value_t *value;
        rdata_var_t *var;
        rdata_ref_t *ref_v;

#ifdef DEBUG_RUN_TRACE
        printf("Run reference literal (nil).\n");
#endif
        (void) run;
        (void) lit_ref;

        item = rdata_item_new(ic_value);
        value = rdata_value_new();
        var = rdata_var_new(vc_ref);
        ref_v = rdata_ref_new();

        item->u.value = value;
        value->var = var;
        var->u.ref_v = ref_v;
        ref_v->vref = NULL;

        *res = item;
}

/** Evaluate string literal. */
static void run_lit_string(run_t *run, stree_lit_string_t *lit_string,
    rdata_item_t **res)
{
        rdata_item_t *item;
        rdata_value_t *value;
        rdata_var_t *var;
        rdata_string_t *string_v;

#ifdef DEBUG_RUN_TRACE
        printf("Run integer literal.\n");
#endif
        (void) run;

        item = rdata_item_new(ic_value);
        value = rdata_value_new();
        var = rdata_var_new(vc_string);
        string_v = rdata_string_new();

        item->u.value = value;
        value->var = var;
        var->u.string_v = string_v;
        string_v->value = lit_string->value;

        *res = item;
}

/** Evaluate @c self reference. */
static void run_self_ref(run_t *run, stree_self_ref_t *self_ref,
    rdata_item_t **res)
{
        run_proc_ar_t *proc_ar;

#ifdef DEBUG_RUN_TRACE
        printf("Run self reference.\n");
#endif
        (void) self_ref;
        proc_ar = run_get_current_proc_ar(run);

        /* Return reference to the currently active object. */
        run_reference(run, proc_ar->obj, res);
}

/** Evaluate binary operation. */
static void run_binop(run_t *run, stree_binop_t *binop, rdata_item_t **res)
{
        rdata_item_t *rarg1_i, *rarg2_i;
        rdata_item_t *rarg1_vi, *rarg2_vi;
        rdata_value_t *v1, *v2;

#ifdef DEBUG_RUN_TRACE
        printf("Run binary operation.\n");
#endif
        run_expr(run, binop->arg1, &rarg1_i);
        run_expr(run, binop->arg2, &rarg2_i);

        switch (binop->bc) {
        case bo_plus:
        case bo_equal:
        case bo_notequal:
        case bo_lt:
        case bo_gt:
        case bo_lt_equal:
        case bo_gt_equal:
                /* These are implemented so far. */
                break;
        default:
                printf("Unimplemented: Binary operation type %d.\n",
                    binop->bc);
                exit(1);
        }

#ifdef DEBUG_RUN_TRACE
        printf("Check binop argument results.\n");
#endif

        run_cvt_value_item(run, rarg1_i, &rarg1_vi);
        run_cvt_value_item(run, rarg2_i, &rarg2_vi);

        v1 = rarg1_vi->u.value;
        v2 = rarg2_vi->u.value;

        if (v1->var->vc != v2->var->vc) {
                printf("Unimplemented: Binary operation arguments have "
                    "different type.\n");
                exit(1);
        }

        switch (v1->var->vc) {
        case vc_int:
                run_binop_int(run, binop, v1, v2, res);
                break;
        case vc_string:
                run_binop_string(run, binop, v1, v2, res);
                break;
        case vc_ref:
                run_binop_ref(run, binop, v1, v2, res);
                break;
        default:
                printf("Unimplemented: Binary operation arguments of "
                    "type %d.\n", v1->var->vc);
                exit(1);
        }
}

/** Evaluate binary operation on int arguments. */
static void run_binop_int(run_t *run, stree_binop_t *binop, rdata_value_t *v1,
    rdata_value_t *v2, rdata_item_t **res)
{
        rdata_item_t *item;
        rdata_value_t *value;
        rdata_var_t *var;
        rdata_int_t *int_v;

        int i1, i2;

        (void) run;

        item = rdata_item_new(ic_value);
        value = rdata_value_new();
        var = rdata_var_new(vc_int);
        int_v = rdata_int_new();

        item->u.value = value;
        value->var = var;
        var->u.int_v = int_v;

        i1 = v1->var->u.int_v->value;
        i2 = v2->var->u.int_v->value;

        switch (binop->bc) {
        case bo_plus:
                int_v->value = i1 + i2;
                break;

        /* XXX We should have a real boolean type. */
        case bo_equal:
                int_v->value = (i1 == i2) ? 1 : 0;
                break;
        case bo_notequal:
                int_v->value = (i1 != i2) ? 1 : 0;
                break;
        case bo_lt:
                int_v->value = (i1 < i2) ? 1 : 0;
                break;
        case bo_gt:
                int_v->value = (i1 > i2) ? 1 : 0;
                break;
        case bo_lt_equal:
                int_v->value = (i1 <= i2) ? 1 : 0;
                break;
        case bo_gt_equal:
                int_v->value = (i1 >= i2) ? 1 : 0;
                break;
        default:
                assert(b_false);
        }

        *res = item;
}

/** Evaluate binary operation on string arguments. */
static void run_binop_string(run_t *run, stree_binop_t *binop, rdata_value_t *v1,
    rdata_value_t *v2, rdata_item_t **res)
{
        rdata_item_t *item;
        rdata_value_t *value;
        rdata_var_t *var;
        rdata_string_t *string_v;

        char *s1, *s2;

        (void) run;

        item = rdata_item_new(ic_value);
        value = rdata_value_new();
        var = rdata_var_new(vc_string);
        string_v = rdata_string_new();

        item->u.value = value;
        value->var = var;
        var->u.string_v = string_v;

        s1 = v1->var->u.string_v->value;
        s2 = v2->var->u.string_v->value;

        switch (binop->bc) {
        case bo_plus:
                /* Concatenate strings. */
                string_v->value = os_str_acat(s1, s2);
                break;
        default:
                printf("Error: Invalid binary operation on string "
                    "arguments (%d).\n", binop->bc);
                assert(b_false);
        }

        *res = item;
}

/** Evaluate binary operation on ref arguments. */
static void run_binop_ref(run_t *run, stree_binop_t *binop, rdata_value_t *v1,
    rdata_value_t *v2, rdata_item_t **res)
{
        rdata_item_t *item;
        rdata_value_t *value;
        rdata_var_t *var;
        rdata_int_t *int_v;

        rdata_var_t *ref1, *ref2;

        (void) run;

        item = rdata_item_new(ic_value);
        value = rdata_value_new();
        var = rdata_var_new(vc_int);
        int_v = rdata_int_new();

        item->u.value = value;
        value->var = var;
        var->u.int_v = int_v;

        ref1 = v1->var->u.ref_v->vref;
        ref2 = v2->var->u.ref_v->vref;

        switch (binop->bc) {
        /* XXX We should have a real boolean type. */
        case bo_equal:
                int_v->value = (ref1 == ref2) ? 1 : 0;
                break;
        case bo_notequal:
                int_v->value = (ref1 != ref2) ? 1 : 0;
                break;
        default:
                printf("Error: Invalid binary operation on reference "
                    "arguments (%d).\n", binop->bc);
                assert(b_false);
        }

        *res = item;
}


/** Evaluate unary operation. */
static void run_unop(run_t *run, stree_unop_t *unop, rdata_item_t **res)
{
        rdata_item_t *rarg;

#ifdef DEBUG_RUN_TRACE
        printf("Run unary operation.\n");
#endif
        run_expr(run, unop->arg, &rarg);
        *res = NULL;
}

/** Evaluate @c new operation. */
static void run_new(run_t *run, stree_new_t *new_op, rdata_item_t **res)
{
        tdata_item_t *titem;

#ifdef DEBUG_RUN_TRACE
        printf("Run 'new' operation.\n");
#endif
        /* Evaluate type expression */
        run_texpr(run->program, run_get_current_csi(run), new_op->texpr,
            &titem);

        switch (titem->tic) {
        case tic_tarray:
                run_new_array(run, new_op, titem, res);
                break;
        case tic_tobject:
                run_new_object(run, new_op, titem, res);
                break;
        default:
                printf("Error: Invalid argument to operator 'new', "
                    "expected object.\n");
                exit(1);
        }
}

/** Create new array. */
static void run_new_array(run_t *run, stree_new_t *new_op,
    tdata_item_t *titem, rdata_item_t **res)
{
        tdata_array_t *tarray;
        rdata_array_t *array;
        rdata_var_t *array_var;
        rdata_var_t *elem_var;

        rdata_item_t *rexpr, *rexpr_vi;
        rdata_var_t *rexpr_var;

        stree_expr_t *expr;

        list_node_t *node;
        int length;
        int i;

#ifdef DEBUG_RUN_TRACE
        printf("Create new array.\n");
#endif
        (void) run;
        (void) new_op;

        assert(titem->tic == tic_tarray);
        tarray = titem->u.tarray;

        /* Create the array. */
        assert(titem->u.tarray->rank > 0);
        array = rdata_array_new(titem->u.tarray->rank);

        /* Compute extents. */
        node = list_first(&tarray->extents);
        if (node == NULL) {
                printf("Error: Extents must be specified when constructing "
                    "an array with 'new'.\n");
                exit(1);
        }

        i = 0; length = 1;
        while (node != NULL) {
                expr = list_node_data(node, stree_expr_t *);

                /* Evaluate extent argument. */
                run_expr(run, expr, &rexpr);
                run_cvt_value_item(run, rexpr, &rexpr_vi);
                assert(rexpr_vi->ic == ic_value);
                rexpr_var = rexpr_vi->u.value->var;

                if (rexpr_var->vc != vc_int) {
                        printf("Error: Array extent must be an integer.\n");
                        exit(1);
                }

#ifdef DEBUG_RUN_TRACE
                printf("Array extent: %d.\n", rexpr_var->u.int_v->value);
#endif
                array->extent[i] = rexpr_var->u.int_v->value;
                length = length * array->extent[i];

                node = list_next(&tarray->extents, node);
                i += 1;
        }

        array->element = calloc(length, sizeof(rdata_var_t *));
        if (array->element == NULL) {
                printf("Memory allocation failed.\n");
                exit(1);
        }

        /* Create member variables */
        for (i = 0; i < length; ++i) {
                /* XXX Depends on member variable type. */
                elem_var = rdata_var_new(vc_int);
                elem_var->u.int_v = rdata_int_new();
                elem_var->u.int_v->value = 0;

                array->element[i] = elem_var;
        }

        /* Create array variable. */
        array_var = rdata_var_new(vc_array);
        array_var->u.array_v = array;

        /* Create reference to the new array. */
        run_reference(run, array_var, res);
}

/** Create new object. */
static void run_new_object(run_t *run, stree_new_t *new_op,
    tdata_item_t *titem, rdata_item_t **res)
{
        rdata_object_t *obj;
        rdata_var_t *obj_var;

        stree_symbol_t *csi_sym;
        stree_csi_t *csi;
        stree_csimbr_t *csimbr;

        rdata_var_t *mbr_var;

        list_node_t *node;

#ifdef DEBUG_RUN_TRACE
        printf("Create new object.\n");
#endif
        (void) run;
        (void) new_op;

        /* Lookup object CSI. */
        assert(titem->tic == tic_tobject);
        csi = titem->u.tobject->csi;
        csi_sym = csi_to_symbol(csi);

        /* Create the object. */
        obj = rdata_object_new();
        obj->class_sym = csi_sym;
        intmap_init(&obj->fields);

        obj_var = rdata_var_new(vc_object);
        obj_var->u.object_v = obj;

        /* Create object fields. */
        node = list_first(&csi->members);
        while (node != NULL) {
                csimbr = list_node_data(node, stree_csimbr_t *);
                if (csimbr->cc == csimbr_var) {
                        /* XXX Depends on member variable type. */
                        mbr_var = rdata_var_new(vc_int);
                        mbr_var->u.int_v = rdata_int_new();
                        mbr_var->u.int_v->value = 0;

                        intmap_set(&obj->fields, csimbr->u.var->name->sid,
                            mbr_var);
                }

                node = list_next(&csi->members, node);
        }

        /* Create reference to the new object. */
        run_reference(run, obj_var, res);
}

/** Evaluate member acccess. */
static void run_access(run_t *run, stree_access_t *access, rdata_item_t **res)
{
        rdata_item_t *rarg;

#ifdef DEBUG_RUN_TRACE
        printf("Run access operation.\n");
#endif
        run_expr(run, access->arg, &rarg);
        if (rarg == NULL) {
                printf("Error: Sub-expression has no value.\n");
                exit(1);
        }

        run_access_item(run, access, rarg, res);
}

/** Evaluate member acccess (with base already evaluated). */
static void run_access_item(run_t *run, stree_access_t *access,
    rdata_item_t *arg, rdata_item_t **res)
{
        var_class_t vc;

#ifdef DEBUG_RUN_TRACE
        printf("Run access operation on pre-evaluated base.\n");
#endif
        vc = run_item_get_vc(run, arg);

        switch (vc) {
        case vc_ref:
                run_access_ref(run, access, arg, res);
                break;
        case vc_deleg:
                run_access_deleg(run, access, arg, res);
                break;
        case vc_object:
                run_access_object(run, access, arg, res);
                break;
        default:
                printf("Unimplemented: Using access operator ('.') "
                    "with unsupported data type (value/%d).\n", vc);
                exit(1);
        }
}

/** Evaluate reference acccess. */
static void run_access_ref(run_t *run, stree_access_t *access,
    rdata_item_t *arg, rdata_item_t **res)
{
        rdata_item_t *darg;

        /* Implicitly dereference. */
        run_dereference(run, arg, &darg);

        /* Try again. */
        run_access_item(run, access, darg, res);
}

/** Evaluate delegate-member acccess. */
static void run_access_deleg(run_t *run, stree_access_t *access,
    rdata_item_t *arg, rdata_item_t **res)
{
        rdata_item_t *arg_vi;
        rdata_value_t *arg_val;
        rdata_deleg_t *deleg_v;
        stree_symbol_t *member;

#ifdef DEBUG_RUN_TRACE
        printf("Run delegate access operation.\n");
#endif
        run_cvt_value_item(run, arg, &arg_vi);
        arg_val = arg_vi->u.value;
        assert(arg_val->var->vc == vc_deleg);

        deleg_v = arg_val->var->u.deleg_v;
        if (deleg_v->obj != NULL || deleg_v->sym->sc != sc_csi) {
                printf("Error: Using '.' with delegate to different object "
                    "than a CSI (%d).\n", deleg_v->sym->sc);
                exit(1);
        }

        member = symbol_search_csi(run->program, deleg_v->sym->u.csi,
            access->member_name);

        if (member == NULL) {
                printf("Error: CSI '");
                symbol_print_fqn(deleg_v->sym);
                printf("' has no member named '%s'.\n",
                    strtab_get_str(access->member_name->sid));
                exit(1);
        }

#ifdef DEBUG_RUN_TRACE
        printf("Found member '%s'.\n",
            strtab_get_str(access->member_name->sid));
#endif

        /*
         * Reuse existing item, value, var, deleg.
         * XXX This is maybe not a good idea because it complicates memory
         * management as there is not a single owner 
         */
        deleg_v->sym = member;
        *res = arg;
}

/** Evaluate object member acccess. */
static void run_access_object(run_t *run, stree_access_t *access,
    rdata_item_t *arg, rdata_item_t **res)
{
        stree_symbol_t *member;
        rdata_var_t *object_var;
        rdata_object_t *object;
        rdata_item_t *ritem;
        rdata_address_t *address;
        rdata_addr_var_t *addr_var;
        rdata_addr_prop_t *addr_prop;
        rdata_aprop_named_t *aprop_named;
        rdata_deleg_t *deleg_p;

        rdata_value_t *value;
        rdata_deleg_t *deleg_v;
        rdata_var_t *var;

#ifdef DEBUG_RUN_TRACE
        printf("Run object access operation.\n");
#endif
        assert(arg->ic == ic_address);
        assert(arg->u.address->ac == ac_var);
        assert(arg->u.address->u.var_a->vref->vc == vc_object);

        object_var = arg->u.address->u.var_a->vref;
        object = object_var->u.object_v;

        member = symbol_search_csi(run->program, object->class_sym->u.csi,
            access->member_name);

        if (member == NULL) {
                printf("Error: Object of class '");
                symbol_print_fqn(object->class_sym);
                printf("' has no member named '%s'.\n",
                    strtab_get_str(access->member_name->sid));
                exit(1);
        }

#ifdef DEBUG_RUN_TRACE
        printf("Found member '%s'.\n",
            strtab_get_str(access->member_name->sid));
#endif

        switch (member->sc) {
        case sc_csi:
                printf("Error: Accessing object member which is nested CSI.\n");
                exit(1);
        case sc_fun:
                /* Construct delegate. */
                ritem = rdata_item_new(ic_value);
                value = rdata_value_new();
                ritem->u.value = value;

                var = rdata_var_new(vc_deleg);
                value->var = var;
                deleg_v = rdata_deleg_new();
                var->u.deleg_v = deleg_v;

                deleg_v->obj = arg->u.address->u.var_a->vref;
                deleg_v->sym = member;
                break;
        case sc_var:
                /* Construct variable address item. */
                ritem = rdata_item_new(ic_address);
                address = rdata_address_new(ac_var);
                addr_var = rdata_addr_var_new();
                ritem->u.address = address;
                address->u.var_a = addr_var;

                addr_var->vref = intmap_get(&object->fields,
                    access->member_name->sid);
                assert(addr_var->vref != NULL);
                break;
        case sc_prop:
                /* Construct named property address. */
                ritem = rdata_item_new(ic_address);
                address = rdata_address_new(ac_prop);
                addr_prop = rdata_addr_prop_new(apc_named);
                aprop_named = rdata_aprop_named_new();
                ritem->u.address = address;
                address->u.prop_a = addr_prop;
                addr_prop->u.named = aprop_named;

                deleg_p = rdata_deleg_new();
                deleg_p->obj = object_var;
                deleg_p->sym = member;
                addr_prop->u.named->prop_d = deleg_p;
                break;
        }

        *res = ritem;
}

/** Call a function. */
static void run_call(run_t *run, stree_call_t *call, rdata_item_t **res)
{
        rdata_item_t *rfun;
        rdata_deleg_t *deleg_v;
        list_t arg_vals;
        list_node_t *node;
        stree_expr_t *arg;
        rdata_item_t *rarg_i, *rarg_vi;

        stree_fun_t *fun;
        run_proc_ar_t *proc_ar;

#ifdef DEBUG_RUN_TRACE
        printf("Run call operation.\n");
#endif
        run_expr(run, call->fun, &rfun);

        if (rfun->ic != ic_value || rfun->u.value->var->vc != vc_deleg) {
                printf("Unimplemented: Call expression of this type.\n");
                *res = NULL;
                return;
        }

        deleg_v = rfun->u.value->var->u.deleg_v;

        if (deleg_v->sym->sc != sc_fun) {
                printf("Error: Called symbol is not a function.\n");
                exit(1);
        }

#ifdef DEBUG_RUN_TRACE
        printf("Call function '");
        symbol_print_fqn(deleg_v->sym);
        printf("'\n");
#endif
        /* Evaluate function arguments. */
        list_init(&arg_vals);
        node = list_first(&call->args);

        while (node != NULL) {
                arg = list_node_data(node, stree_expr_t *);
                run_expr(run, arg, &rarg_i);
                run_cvt_value_item(run, rarg_i, &rarg_vi);

                list_append(&arg_vals, rarg_vi);
                node = list_next(&call->args, node);
        }

        fun = symbol_to_fun(deleg_v->sym);
        assert(fun != NULL);

        /* Create procedure activation record. */
        run_proc_ar_create(run, deleg_v->obj, fun->proc, &proc_ar);

        /* Fill in argument values. */
        run_proc_ar_set_args(run, proc_ar, &arg_vals);

        /* Run the function. */
        run_proc(run, proc_ar, res);

#ifdef DEBUG_RUN_TRACE
        printf("Returned from function call.\n");
#endif
}

/** Run index operation. */
static void run_index(run_t *run, stree_index_t *index, rdata_item_t **res)
{
        rdata_item_t *rbase;
        rdata_item_t *base_i;
        list_node_t *node;
        stree_expr_t *arg;
        rdata_item_t *rarg_i, *rarg_vi;
        var_class_t vc;
        list_t arg_vals;

#ifdef DEBUG_RUN_TRACE
        printf("Run index operation.\n");
#endif
        run_expr(run, index->base, &rbase);

        vc = run_item_get_vc(run, rbase);

        /* Implicitly dereference. */
        if (vc == vc_ref) {
                run_dereference(run, rbase, &base_i);
        } else {
                base_i = rbase;
        }

        vc = run_item_get_vc(run, base_i);

        /* Evaluate arguments (indices). */
        node = list_first(&index->args);
        list_init(&arg_vals);

        while (node != NULL) {
                arg = list_node_data(node, stree_expr_t *);
                run_expr(run, arg, &rarg_i);
                run_cvt_value_item(run, rarg_i, &rarg_vi);

                list_append(&arg_vals, rarg_vi);

                node = list_next(&index->args, node);
        }

        switch (vc) {
        case vc_array:
                run_index_array(run, index, base_i, &arg_vals, res);
                break;
        case vc_object:
                run_index_object(run, index, base_i, &arg_vals, res);
                break;
        case vc_string:
                run_index_string(run, index, base_i, &arg_vals, res);
                break;
        default:
                printf("Error: Indexing object of bad type (%d).\n", vc);
                exit(1);
        }
}

/** Run index operation on array. */
static void run_index_array(run_t *run, stree_index_t *index,
    rdata_item_t *base, list_t *args, rdata_item_t **res)
{
        list_node_t *node;
        rdata_array_t *array;
        rdata_item_t *arg;

        int i;
        int elem_index;
        int arg_val;

        rdata_item_t *ritem;
        rdata_address_t *address;
        rdata_addr_var_t *addr_var;

#ifdef DEBUG_RUN_TRACE
        printf("Run array index operation.\n");
#endif
        (void) run;
        (void) index;

        assert(base->ic == ic_address);
        assert(base->u.address->ac == ac_var);
        assert(base->u.address->u.var_a->vref->vc == vc_array);
        array = base->u.address->u.var_a->vref->u.array_v;

        /*
         * Linear index of the desired element. Elements are stored in
         * lexicographic order with the last index changing the fastest.
         */
        elem_index = 0;

        node = list_first(args);
        i = 0;

        while (node != NULL) {
                if (i >= array->rank) {
                        printf("Error: Too many indices for array of rank %d",
                            array->rank);
                        exit(1);
                }

                arg = list_node_data(node, rdata_item_t *);
                assert(arg->ic == ic_value);

                if (arg->u.value->var->vc != vc_int) {
                        printf("Error: Array index is not an integer.\n");
                        exit(1);
                }

                arg_val = arg->u.value->var->u.int_v->value;

                if (arg_val < 0 || arg_val >= array->extent[i]) {
                        printf("Error: Array index (value: %d) is out of range.\n",
                            arg_val);
                        exit(1);
                }

                elem_index = elem_index * array->extent[i] + arg_val;

                node = list_next(args, node);
                i += 1;
        }

        if (i < array->rank) {
                printf("Error: Too few indices for array of rank %d",
                    array->rank);
                exit(1);
        }

        /* Construct variable address item. */
        ritem = rdata_item_new(ic_address);
        address = rdata_address_new(ac_var);
        addr_var = rdata_addr_var_new();
        ritem->u.address = address;
        address->u.var_a = addr_var;

        addr_var->vref = array->element[elem_index];

        *res = ritem;
}

/** Index an object (via its indexer). */
static void run_index_object(run_t *run, stree_index_t *index,
    rdata_item_t *base, list_t *args, rdata_item_t **res)
{
        rdata_item_t *ritem;
        rdata_address_t *address;
        rdata_addr_prop_t *addr_prop;
        rdata_aprop_indexed_t *aprop_indexed;
        rdata_var_t *obj_var;
        stree_csi_t *obj_csi;
        rdata_deleg_t *object_d;
        stree_symbol_t *indexer_sym;
        stree_ident_t *indexer_ident;

        list_node_t *node;
        rdata_item_t *arg;

#ifdef DEBUG_RUN_TRACE
        printf("Run object index operation.\n");
#endif
        (void) index;

        /* Construct property address item. */
        ritem = rdata_item_new(ic_address);
        address = rdata_address_new(ac_prop);
        addr_prop = rdata_addr_prop_new(apc_indexed);
        aprop_indexed = rdata_aprop_indexed_new();
        ritem->u.address = address;
        address->u.prop_a = addr_prop;
        addr_prop->u.indexed = aprop_indexed;

        if (base->ic != ic_address || base->u.address->ac != ac_var) {
                /* XXX Several other cases can occur. */
                printf("Unimplemented: Indexing object varclass via something "
                    "which is not a simple variable reference.\n");
                exit(1);
        }

        /* Find indexer symbol. */
        obj_var = base->u.address->u.var_a->vref;
        assert(obj_var->vc == vc_object);
        indexer_ident = stree_ident_new();
        indexer_ident->sid = strtab_get_sid(INDEXER_IDENT);
        obj_csi = symbol_to_csi(obj_var->u.object_v->class_sym);
        assert(obj_csi != NULL);
        indexer_sym = symbol_search_csi(run->program, obj_csi, indexer_ident);

        if (indexer_sym == NULL) {
                printf("Error: Accessing object which does not have an "
                    "indexer.\n");
                exit(1);
        }

        /* Construct delegate. */
        object_d = rdata_deleg_new();
        object_d->obj = obj_var;
        object_d->sym = indexer_sym;
        aprop_indexed->object_d = object_d;

        /* Copy list of argument values. */
        list_init(&aprop_indexed->args);

        node = list_first(args);
        while (node != NULL) {
                arg = list_node_data(node, rdata_item_t *);
                list_append(&aprop_indexed->args, arg);
                node = list_next(args, node);
        }

        *res = ritem;
}

/** Run index operation on string. */
static void run_index_string(run_t *run, stree_index_t *index,
    rdata_item_t *base, list_t *args, rdata_item_t **res)
{
        list_node_t *node;
        rdata_string_t *string;
        rdata_item_t *base_vi;
        rdata_item_t *arg;

        int i;
        int elem_index;
        int arg_val;
        int rc;

        rdata_value_t *value;
        rdata_var_t *cvar;
        rdata_item_t *ritem;
        int cval;

#ifdef DEBUG_RUN_TRACE
        printf("Run string index operation.\n");
#endif
        (void) run;
        (void) index;

        run_cvt_value_item(run, base, &base_vi);
        assert(base_vi->u.value->var->vc == vc_string);
        string = base->u.value->var->u.string_v;

        /*
         * Linear index of the desired element. Elements are stored in
         * lexicographic order with the last index changing the fastest.
         */
        node = list_first(args);
        elem_index = 0;

        i = 0;
        while (node != NULL) {
                if (i >= 1) {
                        printf("Error: Too many indices string.\n");
                        exit(1);
                }

                arg = list_node_data(node, rdata_item_t *);
                assert(arg->ic == ic_value);

                if (arg->u.value->var->vc != vc_int) {
                        printf("Error: String index is not an integer.\n");
                        exit(1);
                }

                arg_val = arg->u.value->var->u.int_v->value;
                elem_index = arg_val;

                node = list_next(args, node);
                i += 1;
        }

        if (i < 1) {
                printf("Error: Too few indices for string.\n");
                exit(1);
        }

        rc = os_str_get_char(string->value, elem_index, &cval);
        if (rc != EOK) {
                printf("Error: String index (value: %d) is out of range.\n",
                    arg_val);
                exit(1);
        }

        /* Construct character value. */
        ritem = rdata_item_new(ic_value);
        value = rdata_value_new();
        ritem->u.value = value;

        cvar = rdata_var_new(vc_int);
        cvar->u.int_v = rdata_int_new();
        cvar->u.int_v->value = cval;
        value->var = cvar;

        *res = ritem;
}

/** Execute assignment. */
static void run_assign(run_t *run, stree_assign_t *assign, rdata_item_t **res)
{
        rdata_item_t *rdest_i, *rsrc_i;
        rdata_item_t *rsrc_vi;
        rdata_value_t *src_val;

#ifdef DEBUG_RUN_TRACE
        printf("Run assign operation.\n");
#endif
        run_expr(run, assign->dest, &rdest_i);
        run_expr(run, assign->src, &rsrc_i);

        run_cvt_value_item(run, rsrc_i, &rsrc_vi);
        assert(rsrc_vi->ic == ic_value);
        src_val = rsrc_vi->u.value;

        if (rdest_i->ic != ic_address) {
                printf("Error: Address expression required on left side of "
                    "assignment operator.\n");
                exit(1);
        }

        run_address_write(run, rdest_i->u.address, rsrc_vi->u.value);

        *res = NULL;
}

/** Execute @c as conversion. */
static void run_as(run_t *run, stree_as_t *as_op, rdata_item_t **res)
{
        rdata_item_t *rarg_i;
        rdata_item_t *rarg_vi;
        rdata_item_t *rarg_di;
        rdata_var_t *arg_vref;
        tdata_item_t *dtype;
        run_proc_ar_t *proc_ar;

        stree_symbol_t *obj_csi_sym;
        stree_csi_t *obj_csi;

#ifdef DEBUG_RUN_TRACE
        printf("Run @c as conversion operation.\n");
#endif
        run_expr(run, as_op->arg, &rarg_i);

        /*
         * This should always be a reference if the argument is indeed
         * a class instance.
         */
        assert(run_item_get_vc(run, rarg_i) == vc_ref);
        run_cvt_value_item(run, rarg_i, &rarg_vi);
        assert(rarg_vi->ic == ic_value);

        if (rarg_vi->u.value->var->u.ref_v->vref == NULL) {
                /* Nil reference is always okay. */
                *res = rarg_vi;
                return;
        }

        run_dereference(run, rarg_vi, &rarg_di);

        /* Now we should have a variable address. */
        assert(rarg_di->ic == ic_address);
        assert(rarg_di->u.address->ac == ac_var);

        arg_vref = rarg_di->u.address->u.var_a->vref;

        proc_ar = run_get_current_proc_ar(run);
        /* XXX Memoize to avoid recomputing. */
        run_texpr(run->program, proc_ar->proc->outer_symbol->outer_csi,
            as_op->dtype, &dtype);

        assert(arg_vref->vc == vc_object);
        obj_csi_sym = arg_vref->u.object_v->class_sym;
        obj_csi = symbol_to_csi(obj_csi_sym);
        assert(obj_csi != NULL);

        if (tdata_is_csi_derived_from_ti(obj_csi, dtype) != b_true) {
                printf("Error: Run-time type conversion error. Object is "
                    "of type '");
                symbol_print_fqn(obj_csi_sym);
                printf("' which is not derived from '");
                tdata_item_print(dtype);
                printf("'.\n");
                exit(1);
        }

        *res = rarg_vi;
}

/** Return boolean value of an item.
 *
 * Tries to interpret @a item as a boolean value. If it is not a boolean
 * value, this generates an error.
 *
 * XXX Currently int supplants the role of a true boolean type.
 */
bool_t run_item_boolean_value(run_t *run, rdata_item_t *item)
{
        rdata_item_t *vitem;
        rdata_var_t *var;

        (void) run;
        run_cvt_value_item(run, item, &vitem);

        assert(vitem->ic == ic_value);
        var = vitem->u.value->var;

        if (var->vc != vc_int) {
                printf("Error: Boolean (int) expression expected.\n");
                exit(1);
        }

        return (var->u.int_v->value != 0);
}