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334
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1 /*
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2 lwexpr.c
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3
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4 Copyright © 2010 William Astle
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5
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6 This file is part of LWTOOLS.
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7
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8 LWTOOLS is free software: you can redistribute it and/or modify it under the
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9 terms of the GNU General Public License as published by the Free Software
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10 Foundation, either version 3 of the License, or (at your option) any later
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11 version.
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12
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13 This program is distributed in the hope that it will be useful, but WITHOUT
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14 ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
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15 FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
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16 more details.
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17
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18 You should have received a copy of the GNU General Public License along with
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19 this program. If not, see <http://www.gnu.org/licenses/>.
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20 */
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21
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22 #include <config.h>
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23
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24 #include <stdarg.h>
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25 #include <stdio.h>
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26 #include <string.h>
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27
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28 #define ___lw_expr_c_seen___
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29 #include "lw_alloc.h"
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30 #include "lw_expr.h"
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31 #include "lw_error.h"
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32 #include "lw_string.h"
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33
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34 lw_expr_t lw_expr_create(void)
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35 {
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36 lw_expr_t r;
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37
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38 r = lw_alloc(sizeof(struct lw_expr_priv));
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39 r -> refcount = 1;
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40 r -> operands = NULL;
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41
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42 return r;
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43 }
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44
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45 /* useful for constant expression construction */
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46 /* lw_expr_deref(lw_expr_create(...)) */
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47 /* use of this function on an expression that is not already referenced by the caller */
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48 lw_expr_t lw_expr_deref(lw_expr_t r)
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49 {
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50 r -> refcount--;
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51 return r;
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52 }
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53
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54 void lw_expr_destroy(lw_expr_t E)
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55 {
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56 E -> refcount--;
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57 if (E -> refcount <= 0)
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58 {
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59 struct lw_expr_opers *o;
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60 for (o = E -> operands; o; o = o -> next)
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61 lw_expr_destroy(o -> p);
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62 if (E -> type == lw_expr_type_var)
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63 lw_free(E -> value2);
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64 lw_free(E);
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65 }
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66 }
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67
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68 lw_expr_t lw_expr_copy(lw_expr_t E)
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69 {
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70 E -> refcount++;
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71 return E;
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72 }
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73
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74 void lw_expr_add_operand(lw_expr_t E, lw_expr_t O)
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75 {
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76 struct lw_expr_opers *o, *t;
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77
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78 o = lw_alloc(sizeof(struct lw_expr_opers));
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79 o -> p = lw_expr_copy(O);
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80 o -> next = NULL;
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81 for (t = E -> operands; t && t -> next; t = t -> next)
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82 /* do nothing */ ;
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83
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84 if (t)
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85 t -> next = o;
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86 else
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87 E -> operands = o;
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88 }
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89
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90 /* actually duplicates the entire expression */
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91 lw_expr_t lw_expr_deepcopy(lw_expr_t E)
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92 {
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93 lw_expr_t r, t;
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94 struct lw_expr_opers *o;
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95
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96 r = lw_alloc(sizeof(struct lw_expr_priv));
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97 *r = *E;
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98 r -> refcount = 1;
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335
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99 r -> operands = NULL;
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100
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334
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101 if (E -> type == lw_expr_type_var)
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102 r -> value2 = lw_strdup(E -> value2);
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335
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103 for (o = E -> operands; o; o = o -> next)
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334
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104 {
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105 lw_expr_add_operand(r, lw_expr_deref(lw_expr_deepcopy(o -> p)));
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106 }
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107
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108 return r;
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109 }
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110
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335
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111 lw_expr_t lw_expr_build_aux(int exprtype, va_list args)
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334
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112 {
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113 lw_expr_t r;
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114 int t;
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115 void *p;
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116
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117 lw_expr_t te1, te2;
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118
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119 r = lw_expr_create();
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120
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121 switch (exprtype)
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122 {
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123 case lw_expr_type_int:
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124 t = va_arg(args, int);
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125 r -> type = lw_expr_type_int;
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126 r -> value = t;
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127 break;
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128
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129 case lw_expr_type_var:
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130 p = va_arg(args, char *);
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131 r -> type = lw_expr_type_var;
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132 r -> value2 = lw_strdup(p);
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133 break;
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134
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135 case lw_expr_type_special:
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136 t = va_arg(args, int);
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137 p = va_arg(args, char *);
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138 r -> type = lw_expr_type_special;
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139 r -> value2 = p;
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140 break;
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141
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142 case lw_expr_type_oper:
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143 t = va_arg(args, int);
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144 te1 = va_arg(args, lw_expr_t);
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145 if (t != lw_expr_oper_com && t != lw_expr_oper_neg)
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146 te2 = va_arg(args, lw_expr_t);
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147 else
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148 te2 = NULL;
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149
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150 r -> type = lw_expr_type_oper;
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151 r -> value = t;
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152 lw_expr_add_operand(r, te1);
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153 lw_expr_add_operand(r, te2);
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154 break;
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155
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156 default:
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157 lw_error("Invalid expression type specified to lw_expr_build");
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158 }
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159
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335
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160 return r;
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161 }
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162
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163 lw_expr_t lw_expr_build(int exprtype, ...)
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164 {
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165 va_list args;
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166 lw_expr_t r;
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167
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168 va_start(args, exprtype);
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169 r = lw_expr_build_aux(exprtype, args);
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170 va_end(args);
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171 return r;
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172 }
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173
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174 lw_expr_t lw_expr_build_noref(int exprtype, ...)
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175 {
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176 va_list args;
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177 lw_expr_t r;
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178
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179 va_start(args, exprtype);
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180 r = lw_expr_build_aux(exprtype, args);
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181 r -> refcount--;
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334
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182 va_end(args);
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183 return r;
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184 }
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185
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186 void lw_expr_print(lw_expr_t E)
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187 {
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188 struct lw_expr_opers *o;
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335
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189 int c = 0;
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190
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334
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191 for (o = E -> operands; o; o = o -> next)
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192 {
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335
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193 c++;
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334
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194 lw_expr_print(o -> p);
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195 }
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196
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197 switch (E -> type)
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198 {
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199 case lw_expr_type_int:
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200 printf("%d ", E -> value);
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201 break;
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335
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202
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203 case lw_expr_type_var:
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204 printf("V(%s) ", (char *)(E -> value2));
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205 break;
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206
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207 case lw_expr_type_special:
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208 printf("S(%d,%p) ", E -> value, E -> value2);
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209 break;
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210
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334
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211 case lw_expr_type_oper:
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335
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212 printf("[%d]", c);
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334
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213 switch (E -> value)
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214 {
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215 case lw_expr_oper_plus:
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216 printf("+ ");
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217 break;
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218
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219 case lw_expr_oper_minus:
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220 printf("- ");
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221 break;
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222
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223 case lw_expr_oper_times:
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224 printf("* ");
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225 break;
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226
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227 case lw_expr_oper_divide:
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228 printf("/ ");
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229 break;
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230
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231 case lw_expr_oper_mod:
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232 printf("%% ");
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233 break;
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234
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235 case lw_expr_oper_intdiv:
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236 printf("\\ ");
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237 break;
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238
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239 case lw_expr_oper_bwand:
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240 printf("BWAND ");
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241 break;
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242
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243 case lw_expr_oper_bwor:
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244 printf("BWOR ");
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245 break;
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246
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247 case lw_expr_oper_bwxor:
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248 printf("BWXOR ");
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249 break;
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250
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251 case lw_expr_oper_and:
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252 printf("AND ");
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253 break;
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254
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255 case lw_expr_oper_or:
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256 printf("OR ");
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257 break;
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258
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259 case lw_expr_oper_neg:
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260 printf("NEG ");
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261 break;
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262
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263 case lw_expr_oper_com:
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264 printf("COM ");
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265 break;
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266
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267 default:
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268 printf("OPER ");
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269 break;
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270 }
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271 break;
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272 default:
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273 printf("ERR ");
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274 break;
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275 }
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276 }
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277
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278 /*
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279 Return:
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280 nonzero if expressions are the same (identical pointers or matching values)
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281 zero if expressions are not the same
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282
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283 */
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284 int lw_expr_compare(lw_expr_t E1, lw_expr_t E2)
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285 {
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286 struct lw_expr_opers *o1, *o2;
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287
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288 if (E1 == E2)
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289 return 1;
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290
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291 if (!(E1 -> type == E2 -> type && E1 -> value == E2 -> value))
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292 return 0;
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293
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294 if (E1 -> type == lw_expr_type_var)
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295 {
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296 if (!strcmp(E1 -> value2, E2 -> value2))
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297 return 1;
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298 else
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299 return 0;
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300 }
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301
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302 if (E1 -> type == lw_expr_type_special)
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303 {
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304 if (E1 -> value2 == E2 -> value2)
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305 return 1;
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306 else
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307 return 0;
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308 }
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309
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310 for (o1 = E1 -> operands, o2 = E2 -> operands; o1 && o2; o1 = o1 -> next, o2 = o2 -> next)
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311 if (lw_expr_compare(o1 -> p, o2 -> p) == 0)
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312 return 0;
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313 if (o1 || o2)
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314 return 0;
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315
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316 return 1;
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317 }
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318
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319 /* return true if E is an operator of type oper */
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320 int lw_expr_isoper(lw_expr_t E, int oper)
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321 {
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322 if (E -> type == lw_expr_type_oper && E -> value == oper)
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323 return 1;
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324 return 0;
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325 }
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335
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326
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327
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328 void lw_expr_simplify_sortconstfirst(lw_expr_t E)
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329 {
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330 struct lw_expr_opers *o;
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331
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332 for (o = E -> operands; o; o = o -> next)
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333 lw_expr_simplify_sortconstfirst(o -> p);
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334
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335 for (o = E -> operands; o; o = o -> next)
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336 {
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337 if (o -> p -> type == lw_expr_type_int && o != E -> operands)
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338 {
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339 struct lw_expr_opers *o2;
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340 for (o2 = E -> operands; o2 -> next != o; o2 = o2 -> next)
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341 /* do nothing */ ;
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342 o2 -> next = o -> next;
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343 o -> next = E -> operands;
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344 E -> operands = o;
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345 o = o2;
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346 }
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347 }
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348 }
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349
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336
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350 void lw_expr_sortoperandlist(struct lw_expr_opers **o)
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351 {
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352 fprintf(stderr, "lw_expr_sortoperandlist() not yet implemented\n");
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353 }
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354
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335
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355 // return 1 if the operand lists match, 0 if not
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356 // may re-order the argument lists
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357 int lw_expr_simplify_compareoperandlist(struct lw_expr_opers **ol1, struct lw_expr_opers **ol2)
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358 {
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359 struct lw_expr_opers *o1, *o2;
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360
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361 lw_expr_sortoperandlist(ol1);
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362 lw_expr_sortoperandlist(ol2);
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363
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364 for (o1 = *ol1, o2 = *ol2; o1 && o2; o1 = o1 -> next, o2 = o2 -> next)
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365 {
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366 if (!lw_expr_compare(o1 -> p, o2 -> p))
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367 return 0;
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368 }
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369 if (o1 || o2)
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370 return 0;
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371 return 1;
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372 }
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373
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374 void lw_expr_simplify(lw_expr_t E)
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375 {
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376 struct lw_expr_opers *o;
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377
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378 // sort "constants" to the start of each operand list for + and *
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379 lw_expr_simplify_sortconstfirst(E);
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380
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381 // non-operators have no simplification to do!
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382 if (E -> type != lw_expr_type_oper)
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383 return;
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384
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385 if (E -> value == lw_expr_oper_times)
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386 {
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387 for (o = E -> operands; o; o = o -> next)
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388 {
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389 if (o -> p -> type == lw_expr_type_int && o -> p -> value == 0)
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390 {
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391 // one operand of times is 0, replace operation with 0
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392 while (E -> operands)
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393 {
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394 o = E -> operands;
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395 E -> operands = o -> next;
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396 lw_expr_destroy(o -> p);
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397 lw_free(o);
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398 }
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399 E -> type = lw_expr_type_int;
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400 E -> value = 0;
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401 return;
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402 }
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403 }
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404 }
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405
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406 // look for like terms and collect them together
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407 if (E -> value == lw_expr_oper_plus)
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408 {
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409 for (o = E -> operands; o; o = o -> next)
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410 {
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411 if (o -> p -> type == lw_expr_type_oper && o -> p -> value == lw_expr_oper_times)
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412 {
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413 // we have a "times" here
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414 // find first non-const operand
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415 struct lw_expr_opers *op1, *op2, *o2;
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416 for (op1 = o -> p -> operands; op1; op1 = op1 -> next)
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417 if (op1 -> p -> type != lw_expr_type_int)
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418 break;
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419
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420 for (o2 = o -> next; o2; o2 = o2 -> next)
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421 {
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422 if (o2 -> p -> type == lw_expr_type_oper && o2 -> p -> value == lw_expr_oper_times)
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423 {
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424 // another "times"
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425 for (op2 = o2 -> p -> operands; op2; op2 = op2 -> next)
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426 if (op2 -> p -> type != lw_expr_type_int)
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427 break;
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428
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336
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429 if (lw_expr_simplify_compareoperandlist(&op1, &op2))
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335
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430 {
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431 // we have like terms here
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432 // do something about it
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433 }
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434 }
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435 }
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436 }
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437 }
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438 }
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439
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440
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441 for (o = E -> operands; o; o = o -> next)
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442 lw_expr_simplify(o -> p);
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443
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444 if (E -> value == lw_expr_oper_plus)
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445 {
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446 int c = 0, t = 0;
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447 for (o = E -> operands; o; o = o -> next)
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448 {
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449 t++;
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450 if (!(o -> p -> type == lw_expr_type_int && o -> p -> value == 0))
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451 {
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452 c++;
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453 }
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454 }
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455 if (c == 1)
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456 {
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457 lw_expr_t r;
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458 // find the value and "move it up"
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459 while (E -> operands)
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460 {
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461 o = E -> operands;
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462 if (o -> p -> type != lw_expr_type_int || o -> p -> value != 0)
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463 {
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464 r = lw_expr_deepcopy(o -> p);
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465 }
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466 E -> operands = o -> next;
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467 lw_expr_destroy(o -> p);
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468 lw_free(o);
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469 }
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470 *E = *r;
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471 return;
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472 }
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473 else if (c == 0)
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474 {
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475 // replace with 0
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|
|
476 while (E -> operands)
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477 {
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|
478 o = E -> operands;
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|
479 E -> operands = o -> next;
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|
|
480 lw_expr_destroy(o -> p);
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|
|
481 lw_free(o);
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|
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482 }
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|
|
483 E -> type = lw_expr_type_int;
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|
|
484 E -> value = 0;
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|
|
485 return;
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|
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486 }
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|
|
487 else if (c != t)
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|
|
488 {
|
|
|
489 // collapse out zero terms
|
|
|
490 struct lw_expr_opers *o2;
|
|
|
491
|
|
|
492 for (o = E -> operands; o; o = o -> next)
|
|
|
493 {
|
|
|
494 if (o -> p -> type == lw_expr_type_int && o -> p -> value == 0)
|
|
|
495 {
|
|
|
496 if (o == E -> operands)
|
|
|
497 {
|
|
|
498 E -> operands = o -> next;
|
|
|
499 lw_expr_destroy(o -> p);
|
|
|
500 lw_free(o);
|
|
|
501 o = E -> operands;
|
|
|
502 }
|
|
|
503 else
|
|
|
504 {
|
|
|
505 for (o2 = E -> operands; o2 -> next == o; o2 = o2 -> next)
|
|
|
506 /* do nothing */ ;
|
|
|
507 o2 -> next = o -> next;
|
|
|
508 lw_expr_destroy(o -> p);
|
|
|
509 lw_free(o);
|
|
|
510 o = o2;
|
|
|
511 }
|
|
|
512 }
|
|
|
513 }
|
|
|
514 }
|
|
|
515 return;
|
|
|
516 }
|
|
|
517 }
|
