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1 | /* classes: h_files */ |
2 | ||
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3 | #ifndef SCM_FLUIDS_H |
4 | #define SCM_FLUIDS_H | |
9482a297 | 5 | |
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6 | /* Copyright (C) 1996,2000,2001 Free Software Foundation, Inc. |
7 | * | |
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8 | * This program is free software; you can redistribute it and/or modify |
9 | * it under the terms of the GNU General Public License as published by | |
10 | * the Free Software Foundation; either version 2, or (at your option) | |
11 | * any later version. | |
dee01b01 | 12 | * |
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13 | * This program is distributed in the hope that it will be useful, |
14 | * but WITHOUT ANY WARRANTY; without even the implied warranty of | |
15 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the | |
16 | * GNU General Public License for more details. | |
dee01b01 | 17 | * |
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18 | * You should have received a copy of the GNU General Public License |
19 | * along with this software; see the file COPYING. If not, write to | |
20 | * the Free Software Foundation, Inc., 59 Temple Place, Suite 330, | |
21 | * Boston, MA 02111-1307 USA | |
22 | * | |
23 | * As a special exception, the Free Software Foundation gives permission | |
24 | * for additional uses of the text contained in its release of GUILE. | |
25 | * | |
26 | * The exception is that, if you link the GUILE library with other files | |
27 | * to produce an executable, this does not by itself cause the | |
28 | * resulting executable to be covered by the GNU General Public License. | |
29 | * Your use of that executable is in no way restricted on account of | |
30 | * linking the GUILE library code into it. | |
31 | * | |
32 | * This exception does not however invalidate any other reasons why | |
33 | * the executable file might be covered by the GNU General Public License. | |
34 | * | |
35 | * This exception applies only to the code released by the | |
36 | * Free Software Foundation under the name GUILE. If you copy | |
37 | * code from other Free Software Foundation releases into a copy of | |
38 | * GUILE, as the General Public License permits, the exception does | |
39 | * not apply to the code that you add in this way. To avoid misleading | |
40 | * anyone as to the status of such modified files, you must delete | |
41 | * this exception notice from them. | |
42 | * | |
43 | * If you write modifications of your own for GUILE, it is your choice | |
44 | * whether to permit this exception to apply to your modifications. | |
45 | * If you do not wish that, delete this exception notice. */ | |
46 | ||
dee01b01 | 47 | \f |
d3a6bc94 | 48 | |
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49 | #include "libguile/__scm.h" |
50 | #include "libguile/root.h" | |
51 | #include "libguile/vectors.h" | |
52 | ||
53 | /* Fluids. | |
54 | ||
55 | Fluids are objects of a certain type (a smob) that can hold one SCM | |
56 | value per dynamic root. That is, modifications to this value are | |
57 | only visible to code that executes within the same dynamic root as | |
58 | the modifying code. When a new dynamic root is constructed, it | |
59 | inherits the values from its parent. Because each thread executes | |
60 | in its own dynamic root, you can use fluids for thread local | |
61 | storage. | |
62 | ||
63 | Each fluid is identified by a small integer. This integer is used | |
64 | to index a vector that holds the values of all fluids. Each root | |
65 | has its own vector. | |
66 | ||
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67 | Currently, you can't get rid a certain fluid if you don't use it |
68 | any longer. The slot that has been allocated for it in the fluid | |
9482a297 | 69 | vector will not be reused for other fluids. Therefore, only use |
b3460a50 | 70 | SCM_MAKE_FLUID or its Scheme variant `make-fluid' in initialization |
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71 | code that is only run once. Nevertheless, it should be possible to |
72 | implement a more lightweight version of fluids on top of this basic | |
73 | mechanism. */ | |
74 | ||
33b001fd | 75 | SCM_API scm_t_bits scm_tc16_fluid; |
9482a297 | 76 | |
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77 | #define SCM_FLUIDP(x) (!SCM_IMP (x) && (SCM_CELL_TYPE (x) == scm_tc16_fluid)) |
78 | #define SCM_FLUID_NUM(x) (SCM_CELL_WORD_1 (x)) | |
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79 | |
80 | /* The fastest way to acces/modify the value of a fluid. These macros | |
b3460a50 | 81 | do no error checking at all. You should only use them when you know |
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82 | that the relevant fluid already exists in the current dynamic root. |
83 | The easiest way to ensure this is to execute a SCM_FLUID_SET_X in the | |
84 | topmost root, for example right after SCM_MAKE_FLUID in your | |
85 | SCM_INIT_MUMBLE routine that gets called from SCM_BOOT_GUILE_1. The | |
86 | first argument is the index number of the fluid, obtained via | |
87 | SCM_FLUID_NUM, not the fluid itself. */ | |
88 | ||
89 | #define SCM_FAST_FLUID_REF(n) (SCM_VELTS(scm_root->fluids)[n]) | |
90 | #define SCM_FAST_FLUID_SET_X(n, val) (SCM_VELTS(scm_root->fluids)[n] = val) | |
91 | ||
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92 | SCM_API SCM scm_make_fluid (void); |
93 | SCM_API SCM scm_fluid_p (SCM fl); | |
94 | SCM_API SCM scm_fluid_ref (SCM fluid); | |
95 | SCM_API SCM scm_fluid_set_x (SCM fluid, SCM value); | |
9482a297 | 96 | |
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97 | SCM_API SCM scm_c_with_fluids (SCM fluids, SCM vals, |
98 | SCM (*cproc)(void *), void *cdata); | |
99 | SCM_API SCM scm_c_with_fluid (SCM fluid, SCM val, | |
100 | SCM (*cproc)(void *), void *cdata); | |
101 | SCM_API SCM scm_with_fluids (SCM fluids, SCM vals, SCM thunk); | |
b3460a50 | 102 | |
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103 | SCM_API SCM scm_make_initial_fluids (void); |
104 | SCM_API void scm_copy_fluids (scm_root_state *); | |
105 | SCM_API void scm_swap_fluids (SCM fluids, SCM vals); | |
106 | SCM_API void scm_swap_fluids_reverse (SCM fluids, SCM vals); | |
9482a297 | 107 | |
33b001fd | 108 | SCM_API void scm_init_fluids (void); |
9482a297 | 109 | |
dee01b01 | 110 | #endif /* SCM_FLUIDS_H */ |
89e00824 ML |
111 | |
112 | /* | |
113 | Local Variables: | |
114 | c-file-style: "gnu" | |
115 | End: | |
116 | */ |