annotate src/symeval.h @ 434:9d177e8d4150 r21-2-25

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date Mon, 13 Aug 2007 11:30:53 +0200
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1 /* Definitions of symbol-value forwarding for XEmacs Lisp interpreter.
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2 Copyright (C) 1985, 1986, 1987, 1992, 1993 Free Software Foundation, Inc.
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3
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4 This file is part of XEmacs.
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5
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6 XEmacs is free software; you can redistribute it and/or modify it
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7 under the terms of the GNU General Public License as published by the
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8 Free Software Foundation; either version 2, or (at your option) any
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9 later version.
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10
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11 XEmacs is distributed in the hope that it will be useful, but WITHOUT
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12 ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
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13 FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
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14 for more details.
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15
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16 You should have received a copy of the GNU General Public License
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17 along with XEmacs; see the file COPYING. If not, write to
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18 the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
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19 Boston, MA 02111-1307, USA. */
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20
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21 /* Synched up with: Not in FSF. */
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22
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23 /* Fsymbol_value checks whether XSYMBOL (sym)->value is one of these,
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24 * and does weird magic stuff if so */
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25
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26 #ifndef _XEMACS_SYMEVAL_H_
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27 #define _XEMACS_SYMEVAL_H_
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28
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29 enum symbol_value_type
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30 {
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31 /* The following tags use the 'symbol_value_forward' structure
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32 and are strictly for variables DEFVARed on the C level. */
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33 SYMVAL_FIXNUM_FORWARD, /* Forward C "int" */
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34 SYMVAL_CONST_FIXNUM_FORWARD, /* Same, but can't be set */
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35 SYMVAL_BOOLEAN_FORWARD, /* Forward C boolean ("int") */
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36 SYMVAL_CONST_BOOLEAN_FORWARD, /* Same, but can't be set */
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37 SYMVAL_OBJECT_FORWARD, /* Forward C Lisp_Object */
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38 SYMVAL_CONST_OBJECT_FORWARD, /* Same, but can't be set */
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39 SYMVAL_CONST_SPECIFIER_FORWARD, /* Same, can't be set, but gives a
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40 different message when attempting to
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41 set that says "use set-specifier" */
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42 SYMVAL_DEFAULT_BUFFER_FORWARD, /* Forward Lisp_Object into Vbuffer_defaults */
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43 SYMVAL_CURRENT_BUFFER_FORWARD, /* Forward Lisp_Object into current_buffer */
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44 SYMVAL_CONST_CURRENT_BUFFER_FORWARD, /* Forward Lisp_Object into
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45 current_buffer, can't be set */
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46 SYMVAL_DEFAULT_CONSOLE_FORWARD, /* Forward Lisp_Object into
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47 Vconsole_defaults */
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48 SYMVAL_SELECTED_CONSOLE_FORWARD, /* Forward Lisp_Object into
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49 Vselected_console */
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50 SYMVAL_CONST_SELECTED_CONSOLE_FORWARD, /* Forward Lisp_Object into
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51 Vselected_console,
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52 can't be set */
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53 SYMVAL_UNBOUND_MARKER, /* Only Qunbound actually has this tag */
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54
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55 /* The following tags use the 'symbol_value_buffer_local' structure */
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56 SYMVAL_BUFFER_LOCAL, /* make-variable-buffer-local */
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57 SYMVAL_SOME_BUFFER_LOCAL, /* make-local-variable */
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58
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59 /* The following tag uses the 'symbol_value_lisp_magic' structure */
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60 SYMVAL_LISP_MAGIC, /* Forward to lisp callbacks */
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61
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62 /* The following tag uses the 'symbol_value_varalias' structure */
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63 SYMVAL_VARALIAS /* defvaralias */
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64
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65 #if 0
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66 /* NYI */
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67 SYMVAL_CONSTANT_SYMBOL, /* Self-evaluating symbol */
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68 /* NYI */
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69 #endif
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70 };
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71
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72 struct symbol_value_magic
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73 {
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74 struct lcrecord_header lcheader;
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75 enum symbol_value_type type;
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76 };
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77 #define SYMBOL_VALUE_MAGIC_P(x) \
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78 (LRECORDP (x) \
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79 && (XRECORD_LHEADER_IMPLEMENTATION (x)->printer \
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80 == print_symbol_value_magic))
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81 #define XSYMBOL_VALUE_MAGIC_TYPE(v) \
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82 (((struct symbol_value_magic *) XPNTR (v))->type)
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83 #define XSETSYMBOL_VALUE_MAGIC(s, p) XSETOBJ (s, Lisp_Type_Record, p)
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84 void print_symbol_value_magic (Lisp_Object, Lisp_Object, int);
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85
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86 /********** The various different symbol-value-magic types ***********/
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87
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88 /* 1. symbol-value-forward */
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89
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90 /* This type of symbol-value-magic is used for variables declared
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91 DEFVAR_LISP, DEFVAR_INT, DEFVAR_BOOL, DEFVAR_BUFFER_LOCAL,
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92 DEFVAR_BUFFER_DEFAULTS, DEFVAR_SPECIFIER, and for Qunbound.
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93
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94 Note that some of these types of variables can be made buffer-local.
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95 Then, the symbol's value field contains a symbol-value-buffer-local,
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96 whose CURRENT-VALUE field then contains a symbol-value-forward.
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97 */
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98
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99 struct symbol_value_forward
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100 {
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101 struct symbol_value_magic magic;
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102
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103 /* `magicfun' is a function controlling the magic behavior of this
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104 forward variable.
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105
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106 SYM is the symbol being operated on (read, set, etc.);
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107
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108 VAL is either the value to set or the value to be returned.
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109
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110 IN_OBJECT is the buffer or console that the value is read in
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111 or set in. A value of Qnil means that the current buffer
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112 and possibly other buffers are being set. (This value will
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113 never be passed for built-in buffer-local or console-local
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114 variables such as `truncate-lines'.) (Currently, a value of
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115 Qnil is always passed for DEFVAR_INT, DEFVAR_LISP, and
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116 DEFVAR_BOOL variables; the code isn't smart enough to figure
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117 out what buffers besides the current buffer are being
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118 affected. Because the magic function is called
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119 before the value is changed, it's not that easy
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120 to determine which buffers are getting changed.
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121 #### If this information is important, let me know
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122 and I will look into providing it.) (Remember also
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123 that the only console-local variables currently existing
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124 are built-in ones, because others can't be created.)
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125
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126 FLAGS gives more information about the operation being performed.
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127
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128 The return value indicates what the magic function actually did.
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129
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130 Currently FLAGS and the return value are not used. This
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131 function is only called when the value of a forward variable
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132 is about to be changed. Note that this can occur explicitly
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133 through a call to `set', `setq', `set-default', or `setq-default',
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134 or implicitly by the current buffer being changed. */
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135 int (*magicfun) (Lisp_Object sym, Lisp_Object *val, Lisp_Object in_object,
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136 int flags);
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137 };
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138 DECLARE_LRECORD (symbol_value_forward, struct symbol_value_forward);
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139 #define XSYMBOL_VALUE_FORWARD(x) \
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140 XRECORD (x, symbol_value_forward, struct symbol_value_forward)
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141 #define symbol_value_forward_forward(m) ((void *)((m)->magic.lcheader.next))
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142 #define symbol_value_forward_magicfun(m) ((m)->magicfun)
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143
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144 /* 2. symbol-value-buffer-local */
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145
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146 struct symbol_value_buffer_local
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147 {
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148 struct symbol_value_magic magic;
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149 /* Used in a symbol value cell when the symbol's value is per-buffer.
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150
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151 The type of the symbol-value-magic will be either
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152 SYMVAL_BUFFER_LOCAL (i.e. `make-variable-buffer-local' was called)
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153 or SYMVAL_SOME_BUFFER_LOCAL (i.e. `make-local-variable' was called).
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154 The only difference between the two is that when setting the
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155 former kind of variable, an implicit `make-local-variable' is
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156 called.
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157
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158 A buffer-local variable logically has
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159
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160 -- a default value
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161 -- local values in some buffers
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162
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163 The primary place where the local values are stored is in each
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164 buffer's local_var_alist slot.
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165
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166 In the simplest implementation, all that this structure needs to
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167 keep track of is the default value; to retrieve the value in
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168 a buffer, look in that buffer's local_var_alist, and use the
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169 default value if there is no local value. To implement
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170 `make-local-variable' in a buffer, look in the buffer's
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171 local_var_alist, and if no element exists for this symbol,
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172 add one, copying the value from the default value. When setting
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173 the value in a buffer, look in the buffer's local_var_alist, and set
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174 the value in that list if an element exists for this symbol;
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175 otherwise, set the default. (Remember that SYMVAL_BUFFER_LOCAL
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176 variables implicitly call `make-local-variable' first, so when
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177 setting a value, there will always be an entry in the buffer's
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178 local_var_alist to set.)
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179
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180 However, this operation is potentially slow. To speed it up,
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181 we cache the value in one buffer in this structure.
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182
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183 NOTE: This is *not* a write-through cache. I.e. when setting
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184 the value in the buffer that is cached, we *only* change the
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185 cache and don't write the value through to either the buffer's
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186 local_var_alist or the default value. Therefore, when retrieving
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187 a value in a buffer, you must *always* look in the cache to see if
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188 it refers to that buffer.
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189
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190 The cache consists of
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191
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192 -- a buffer, or nil if the cache has not been set up
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193 -- the value in that buffer
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194 -- the element (a cons) from the buffer's local_var_alist, or
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195 nil if there is no local value in the buffer
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196
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197 These slots are called CURRENT-BUFFER, CURRENT-VALUE, and
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198 CURRENT-ALIST-ELEMENT, respectively.
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199
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200 If we want to examine or set the value in BUFFER and CURRENT-BUFFER
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201 equals BUFFER, we just examine or set CURRENT-VALUE. Otherwise,
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202 we store CURRENT-VALUE value into CURRENT-ALIST-ELEMENT (or maybe
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203 into DEFAULT-VALUE), then find the appropriate alist element for
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204 BUFFER and set up CURRENT-ALIST-ELEMENT. Then we set CURRENT-VALUE
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205 out of that element (or maybe out of DEFAULT-VALUE), and store
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206 BUFFER into CURRENT-BUFFER.
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207
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208 If we are setting the variable and the current buffer does not have
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209 an alist entry for this variable, an alist entry is created.
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210
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211 Note that CURRENT-BUFFER's local_var_alist value for this variable
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212 might be out-of-date (the correct value is stored in CURRENT-VALUE).
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213 Similarly, if CURRENT-BUFFER sees the default value, then
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214 DEFAULT-VALUE might be out-of-date.
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215
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216 Note that CURRENT-VALUE (but not DEFAULT-VALUE) can be a
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217 forwarding pointer. Each time it is examined or set,
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218 forwarding must be done.
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219 */
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220 Lisp_Object default_value;
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221 Lisp_Object current_value;
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222 Lisp_Object current_buffer;
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223 Lisp_Object current_alist_element;
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224 };
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225 DECLARE_LRECORD (symbol_value_buffer_local, struct symbol_value_buffer_local);
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226 #define XSYMBOL_VALUE_BUFFER_LOCAL(x) \
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227 XRECORD (x, symbol_value_buffer_local, struct symbol_value_buffer_local)
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228 #define SYMBOL_VALUE_BUFFER_LOCAL_P(x) RECORDP (x, symbol_value_buffer_local)
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229
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230 /* 3. symbol-value-lisp-magic */
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231
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232 enum lisp_magic_handler
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233 {
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234 MAGIC_HANDLER_GET_VALUE,
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235 MAGIC_HANDLER_SET_VALUE,
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236 MAGIC_HANDLER_BOUND_PREDICATE,
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237 MAGIC_HANDLER_MAKE_UNBOUND,
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238 MAGIC_HANDLER_LOCAL_PREDICATE,
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239 MAGIC_HANDLER_MAKE_LOCAL,
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240 MAGIC_HANDLER_MAX
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241 };
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242
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243 struct symbol_value_lisp_magic
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244 {
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245 struct symbol_value_magic magic;
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246 Lisp_Object handler[MAGIC_HANDLER_MAX];
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247 Lisp_Object harg[MAGIC_HANDLER_MAX];
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248 Lisp_Object shadowed;
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249 };
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250 DECLARE_LRECORD (symbol_value_lisp_magic, struct symbol_value_lisp_magic);
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251 #define XSYMBOL_VALUE_LISP_MAGIC(x) \
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252 XRECORD (x, symbol_value_lisp_magic, struct symbol_value_lisp_magic)
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253 #define SYMBOL_VALUE_LISP_MAGIC_P(x) RECORDP (x, symbol_value_lisp_magic)
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254
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255 /* 4. symbol-value-varalias */
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256
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257 struct symbol_value_varalias
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258 {
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259 struct symbol_value_magic magic;
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260 Lisp_Object aliasee;
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261 Lisp_Object shadowed;
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262 };
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263 DECLARE_LRECORD (symbol_value_varalias, struct symbol_value_varalias);
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264 #define XSYMBOL_VALUE_VARALIAS(x) \
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265 XRECORD (x, symbol_value_varalias, struct symbol_value_varalias)
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266 #define SYMBOL_VALUE_VARALIAS_P(x) RECORDP (x, symbol_value_varalias)
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267 #define symbol_value_varalias_aliasee(m) ((m)->aliasee)
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268 #define symbol_value_varalias_shadowed(m) ((m)->shadowed)
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269
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270 /* To define a Lisp primitive function using a C function `Fname', do this:
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271 DEFUN ("name, Fname, ...); // at top level in foo.c
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272 DEFSUBR (Fname); // in syms_of_foo();
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273 */
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274 void defsubr (Lisp_Subr *);
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275 #define DEFSUBR(Fname) defsubr (&S##Fname)
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276
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277 /* To define a Lisp primitive macro using a C function `Fname', do this:
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278 DEFUN ("name, Fname, ...); // at top level in foo.c
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279 DEFSUBR_MACRO (Fname); // in syms_of_foo();
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280 */
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281 void defsubr_macro (Lisp_Subr *);
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282 #define DEFSUBR_MACRO(Fname) defsubr_macro (&S##Fname)
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283
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284 void defsymbol (Lisp_Object *location, CONST char *name);
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285 void defsymbol_nodump (Lisp_Object *location, CONST char *name);
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286
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287 void defkeyword (Lisp_Object *location, CONST char *name);
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288
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289 void deferror (Lisp_Object *symbol, CONST char *name,
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290 CONST char *message, Lisp_Object inherits_from);
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291
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292 /* Macros we use to define forwarded Lisp variables.
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293 These are used in the syms_of_FILENAME functions. */
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294
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295 void defvar_magic (CONST char *symbol_name, CONST struct symbol_value_forward *magic);
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296
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297 #define symbol_value_forward_lheader_initializer { 1, 0, 0, 0 }
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298
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299 #define DEFVAR_SYMVAL_FWD(lname, c_location, forward_type, magicfun) do { \
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300 static CONST_IF_NOT_DEBUG struct symbol_value_forward I_hate_C \
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301 = { { { symbol_value_forward_lheader_initializer, \
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302 (struct lcrecord_header *) (c_location), 69 }, \
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303 forward_type }, magicfun }; \
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304 defvar_magic ((lname), &I_hate_C); \
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305 } while (0)
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306
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307 #define DEFVAR_SYMVAL_FWD_OBJECT(lname, c_location, forward_type, magicfun) do{ \
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308 DEFVAR_SYMVAL_FWD (lname, c_location, forward_type, magicfun); \
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309 staticpro (c_location); \
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310 if (EQ (*c_location, Qnull_pointer)) *c_location = Qnil; \
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311 } while (0)
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312
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313 #define DEFVAR_LISP(lname, c_location) \
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314 DEFVAR_SYMVAL_FWD_OBJECT (lname, c_location, SYMVAL_OBJECT_FORWARD, 0)
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315 #define DEFVAR_CONST_LISP(lname, c_location) \
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316 DEFVAR_SYMVAL_FWD_OBJECT (lname, c_location, SYMVAL_CONST_OBJECT_FORWARD, 0)
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317 #define DEFVAR_SPECIFIER(lname, c_location) \
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318 DEFVAR_SYMVAL_FWD_OBJECT (lname, c_location, SYMVAL_CONST_SPECIFIER_FORWARD, 0)
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319 #define DEFVAR_INT(lname, c_location) \
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320 DEFVAR_SYMVAL_FWD (lname, c_location, SYMVAL_FIXNUM_FORWARD, 0)
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321 #define DEFVAR_CONST_INT(lname, c_location) \
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322 DEFVAR_SYMVAL_FWD (lname, c_location, SYMVAL_CONST_FIXNUM_FORWARD, 0)
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323 #define DEFVAR_BOOL(lname, c_location) \
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324 DEFVAR_SYMVAL_FWD (lname, c_location, SYMVAL_BOOLEAN_FORWARD, 0)
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325 #define DEFVAR_CONST_BOOL(lname, c_location) \
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326 DEFVAR_SYMVAL_FWD (lname, c_location, SYMVAL_CONST_BOOLEAN_FORWARD, 0)
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327 #define DEFVAR_LISP_MAGIC(lname, c_location, magicfun) \
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328 DEFVAR_SYMVAL_FWD_OBJECT (lname, c_location, SYMVAL_OBJECT_FORWARD, magicfun);
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329 #define DEFVAR_INT_MAGIC(lname, c_location, magicfun) \
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330 DEFVAR_SYMVAL_FWD (lname, c_location, SYMVAL_FIXNUM_FORWARD, magicfun);
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331 #define DEFVAR_BOOL_MAGIC(lname, c_location, magicfun) \
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332 DEFVAR_SYMVAL_FWD (lname, c_location, SYMVAL_BOOLEAN_FORWARD, magicfun);
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333
3ecd8885ac67 Import from CVS: tag r21-2-22
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334 #endif /* _XEMACS_SYMEVAL_H_ */