/* Copyright (C) 2001-2006 Artifex Software, Inc.
   All Rights Reserved.
  
   This software is provided AS-IS with no warranty, either express or
   implied.

   This software is distributed under license and may not be copied, modified
   or distributed except as expressly authorized under the terms of that
   license.  Refer to licensing information at http://www.artifex.com/
   or contact Artifex Software, Inc.,  7 Mt. Lassen Drive - Suite A-134,
   San Rafael, CA  94903, U.S.A., +1(415)492-9861, for further information.
*/

/* $Id: zmisc2.c 8250 2007-09-25 13:31:24Z giles $ */
/* Miscellaneous Level 2 operators */
#include "memory_.h"
#include "string_.h"
#include "ghost.h"
#include "oper.h"
#include "estack.h"
#include "iddict.h"
#include "idparam.h"
#include "iparam.h"
#include "dstack.h"
#include "ilevel.h"
#include "iname.h"
#include "iutil2.h"
#include "ivmspace.h"
#include "store.h"

/* Forward references */
static int set_language_level(i_ctx_t *, int);

/* ------ Language level operators ------ */

/* - .languagelevel <int> */
static int
zlanguagelevel(i_ctx_t *i_ctx_p)
{
    os_ptr op = osp;

    push(1);
    make_int(op, LANGUAGE_LEVEL);
    return 0;
}

/* <int> .setlanguagelevel - */
static int
zsetlanguagelevel(i_ctx_t *i_ctx_p)
{
    os_ptr op = osp;
    int code = 0;

    check_type(*op, t_integer);
    if (op->value.intval != LANGUAGE_LEVEL) {
	code = set_language_level(i_ctx_p, (int)op->value.intval);
	if (code < 0)
	    return code;
    }
    LANGUAGE_LEVEL = op->value.intval;
    pop(1);
    return code;
}

/* ------ Initialization procedure ------ */

/* The level setting ops are recognized even in Level 1 mode. */
const op_def zmisc2_op_defs[] =
{
    {"0.languagelevel", zlanguagelevel},
    {"1.setlanguagelevel", zsetlanguagelevel},
    op_def_end(0)
};

/* ------ Internal procedures ------ */

/*
 * Adjust the interpreter for a change in language level.
 * This is used for the .setlanguagelevel operator,
 * and (perhaps someday) after a restore.
 */
static int swap_level_dict(i_ctx_t *i_ctx_p, const char *dict_name);
static int swap_entry(i_ctx_t *i_ctx_p, ref elt[2], ref * pdict,
		       ref * pdict2);
static int
set_language_level(i_ctx_t *i_ctx_p, int new_level)
{
    int old_level = LANGUAGE_LEVEL;
    ref *pgdict =		/* globaldict, if present */
	ref_stack_index(&d_stack, ref_stack_count(&d_stack) - 2);
    ref *level2dict;
    int code = 0;

    if (new_level < 1 ||
	new_level >
	(dict_find_string(systemdict, "ll3dict", &level2dict) > 0 ? 3 : 2)
	)
	return_error(e_rangecheck);
    if (dict_find_string(systemdict, "level2dict", &level2dict) <= 0)
	return_error(e_undefined);
    /*
     * As noted in dstack.h, we allocate the extra d-stack entry for
     * globaldict even in Level 1 mode; in Level 1 mode, this entry
     * holds an extra copy of systemdict, and [count]dictstack omit the
     * very bottommost entry.
     */
    while (new_level != old_level) {
	switch (old_level) {
	    case 1: {		/* 1 => 2 or 3 */
				/* Put globaldict in the dictionary stack. */
		ref *pdict;

		/*
		 * This might be called so early in initialization that
		 * globaldict hasn't been defined yet.  If so, just skip
		 * this step.
		 */
		code = dict_find_string(level2dict, "globaldict", &pdict);
		if (code > 0) {
		    if (!r_has_type(pdict, t_dictionary))
			return_error(e_typecheck);
		    *pgdict = *pdict;
		}
		/* Set other flags for Level 2 operation. */
		imemory->gs_lib_ctx->dict_auto_expand = true;
		}
		code = swap_level_dict(i_ctx_p, "level2dict");
		if (code < 0)
		    return code;
		++old_level;
		continue;
	    case 3:		/* 3 => 1 or 2 */
		code = swap_level_dict(i_ctx_p, "ll3dict");
		if (code < 0)
		    return code;
		--old_level;
		continue;
	    default:		/* 2 => 1 or 3 */
		break;
	}
	switch (new_level) {
	    case 1: {		/* 2 => 1 */
		/*
		 * Clear the cached definition pointers of all names defined
		 * in globaldict.  This will slow down future lookups, but
		 * we don't care.
		 */
		int index = dict_first(pgdict);
		ref elt[2];

		while ((index = dict_next(pgdict, index, &elt[0])) >= 0)
		    if (r_has_type(&elt[0], t_name))
		        name_invalidate_value_cache(imemory, &elt[0]);
		/* Overwrite globaldict in the dictionary stack. */
		*pgdict = *systemdict;
		/* Set other flags for Level 1 operation. */
		imemory->gs_lib_ctx->dict_auto_expand = false;
		}
		code = swap_level_dict(i_ctx_p, "level2dict");
		break;
	    case 3:		/* 2 => 3 */
		code = swap_level_dict(i_ctx_p, "ll3dict");
		break;
	    default:		/* not possible */
		return_error(e_Fatal);
	}
	break;
    }
    dict_set_top();		/* reload dict stack cache */
    return code;
}

/*
 * Swap the contents of a level dictionary (level2dict or ll3dict) and
 * systemdict.  If a value in the level dictionary is itself a dictionary,
 * and it contains a key/value pair referring to itself, swap its contents
 * with the contents of the same dictionary in systemdict.  (This is a hack
 * to swap the contents of statusdict.)
 */
static int
swap_level_dict(i_ctx_t *i_ctx_p, const char *dict_name)
{
    ref *pleveldict;
    ref rleveldict;
    int index;
    ref elt[2];			/* key, value */
    ref *psubdict;

    /*
     * We have to copy the refs for leveldict and subdict, since they may
     * move if their containing dictionary is resized.
     */
    if (dict_find_string(systemdict, dict_name, &pleveldict) <= 0)
	return_error(e_undefined);
    rleveldict = *pleveldict;
    index = dict_first(&rleveldict);
    while ((index = dict_next(&rleveldict, index, &elt[0])) >= 0)
	if (r_has_type(&elt[1], t_dictionary) &&
	    dict_find(&elt[1], &elt[0], &psubdict) > 0 &&
	    obj_eq(imemory, &elt[1], psubdict)
	    ) {
	    /* elt[1] is the 2nd-level sub-dictionary */
	    int isub = dict_first(&elt[1]);
	    ref subelt[2];
	    int found = dict_find(systemdict, &elt[0], &psubdict);
	    ref rsubdict;

	    if (found <= 0)
		continue;
	    rsubdict = *psubdict;
	    while ((isub = dict_next(&elt[1], isub, &subelt[0])) >= 0)
	        if (!obj_eq(imemory, &subelt[0], &elt[0])) {
		    /* don't swap dict itself */
		    int code = swap_entry(i_ctx_p, subelt, &rsubdict, &elt[1]);

		    if (code < 0)
			return code;
		}
	} else {
	    int code = swap_entry(i_ctx_p, elt, systemdict, &rleveldict);

	    if (code < 0)
		return code;
	}
    return 0;
}

/*
 * Swap an entry from a higher level dictionary into a base dictionary.
 * elt[0] is the key, elt[1] is the current value in the Level 2 dictionary
 * (*pdict2).
 */
static int
swap_entry(i_ctx_t *i_ctx_p, ref elt[2], ref * pdict, ref * pdict2)
{
    ref *pvalue;
    ref old_value;		/* current value in *pdict */
    int found = dict_find(pdict, &elt[0], &pvalue);

    switch (found) {
	default:		/* <0, error */
	    /*
	     * The only possible error here is a dictfull error, which is
	     * harmless.
	     */
	    /* fall through */
	case 0:		/* missing */
	    make_null(&old_value);
	    break;
	case 1:		/* present */
	    old_value = *pvalue;
    }
    /*
     * Temporarily flag the dictionaries as local, so that we don't
     * get invalidaccess errors.  (We know that they are both
     * referenced from systemdict, so they are allowed to reference
     * local objects even if they are global.)
     */
    {
	uint space2 = r_space(pdict2);
	int code;

	r_set_space(pdict2, avm_local);
	idict_put(pdict2, &elt[0], &old_value);
	if (r_has_type(&elt[1], t_null)) {
	    code = idict_undef(pdict, &elt[0]);
	    if (code == e_undefined &&
		r_has_type(&old_value, t_null)
		)
		code = 0;
	} else {
	    uint space = r_space(pdict);

	    r_set_space(pdict, avm_local);
	    code = idict_put(pdict, &elt[0], &elt[1]);
	    r_set_space(pdict, space);
	}
	r_set_space(pdict2, space2);
	return code;
    }
}
