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116 lines
4.7 KiB
C
116 lines
4.7 KiB
C
/* classes: h_files */
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#ifndef SCM_FLUIDS_H
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#define SCM_FLUIDS_H
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/* Copyright (C) 1996,2000,2001 Free Software Foundation, Inc.
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2, or (at your option)
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* any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this software; see the file COPYING. If not, write to
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* the Free Software Foundation, Inc., 59 Temple Place, Suite 330,
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* Boston, MA 02111-1307 USA
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*
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* As a special exception, the Free Software Foundation gives permission
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* for additional uses of the text contained in its release of GUILE.
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*
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* The exception is that, if you link the GUILE library with other files
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* to produce an executable, this does not by itself cause the
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* resulting executable to be covered by the GNU General Public License.
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* Your use of that executable is in no way restricted on account of
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* linking the GUILE library code into it.
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*
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* This exception does not however invalidate any other reasons why
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* the executable file might be covered by the GNU General Public License.
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*
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* This exception applies only to the code released by the
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* Free Software Foundation under the name GUILE. If you copy
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* code from other Free Software Foundation releases into a copy of
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* GUILE, as the General Public License permits, the exception does
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* not apply to the code that you add in this way. To avoid misleading
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* anyone as to the status of such modified files, you must delete
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* this exception notice from them.
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*
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* If you write modifications of your own for GUILE, it is your choice
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* whether to permit this exception to apply to your modifications.
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* If you do not wish that, delete this exception notice. */
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#include "libguile/__scm.h"
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#include "libguile/root.h"
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#include "libguile/vectors.h"
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/* Fluids.
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Fluids are objects of a certain type (a smob) that can hold one SCM
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value per dynamic root. That is, modifications to this value are
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only visible to code that executes within the same dynamic root as
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the modifying code. When a new dynamic root is constructed, it
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inherits the values from its parent. Because each thread executes
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in its own dynamic root, you can use fluids for thread local
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storage.
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Each fluid is identified by a small integer. This integer is used
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to index a vector that holds the values of all fluids. Each root
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has its own vector.
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Currently, you can't get rid a certain fluid if you don't use it
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any longer. The slot that has been allocated for it in the fluid
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vector will not be reused for other fluids. Therefore, only use
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SCM_MAKE_FLUID or its Scheme variant `make-fluid' in initialization
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code that is only run once. Nevertheless, it should be possible to
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implement a more lightweight version of fluids on top of this basic
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mechanism. */
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SCM_API scm_t_bits scm_tc16_fluid;
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#define SCM_FLUIDP(x) (!SCM_IMP (x) && (SCM_CELL_TYPE (x) == scm_tc16_fluid))
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#define SCM_FLUID_NUM(x) (SCM_CELL_WORD_1 (x))
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/* The fastest way to acces/modify the value of a fluid. These macros
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do no error checking at all. You should only use them when you know
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that the relevant fluid already exists in the current dynamic root.
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The easiest way to ensure this is to execute a SCM_FLUID_SET_X in the
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topmost root, for example right after SCM_MAKE_FLUID in your
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SCM_INIT_MUMBLE routine that gets called from SCM_BOOT_GUILE_1. The
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first argument is the index number of the fluid, obtained via
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SCM_FLUID_NUM, not the fluid itself. */
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#define SCM_FAST_FLUID_REF(n) (SCM_VELTS(scm_root->fluids)[n])
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#define SCM_FAST_FLUID_SET_X(n, val) (SCM_VELTS(scm_root->fluids)[n] = val)
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SCM_API SCM scm_make_fluid (void);
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SCM_API SCM scm_fluid_p (SCM fl);
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SCM_API SCM scm_fluid_ref (SCM fluid);
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SCM_API SCM scm_fluid_set_x (SCM fluid, SCM value);
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SCM_API SCM scm_c_with_fluids (SCM fluids, SCM vals,
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SCM (*cproc)(void *), void *cdata);
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SCM_API SCM scm_c_with_fluid (SCM fluid, SCM val,
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SCM (*cproc)(void *), void *cdata);
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SCM_API SCM scm_with_fluids (SCM fluids, SCM vals, SCM thunk);
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SCM_API SCM scm_make_initial_fluids (void);
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SCM_API void scm_copy_fluids (scm_root_state *);
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SCM_API void scm_swap_fluids (SCM fluids, SCM vals);
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SCM_API void scm_swap_fluids_reverse (SCM fluids, SCM vals);
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SCM_API void scm_init_fluids (void);
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#endif /* SCM_FLUIDS_H */
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/*
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Local Variables:
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c-file-style: "gnu"
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End:
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*/
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