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1087
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1 /*
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2 ** $Id: ltablib.c,v 1.63 2011/11/28 17:26:30 roberto Exp $
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3 ** Library for Table Manipulation
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4 ** See Copyright Notice in lua.h
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5 */
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6
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7
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8 #include <stddef.h>
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9
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10 #define ltablib_c
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11 #define LUA_LIB
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12
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13 #include "lua.h"
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14
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15 #include "lauxlib.h"
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16 #include "lualib.h"
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17
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18
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19 #define aux_getn(L,n) \
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20 (luaL_checktype(L, n, LUA_TTABLE), luaL_len(L, n))
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21
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22
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23 #if defined(LUA_COMPAT_MAXN)
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24 static int maxn (lua_State *L) {
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25 lua_Number max = 0;
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26 luaL_checktype(L, 1, LUA_TTABLE);
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27 lua_pushnil(L); /* first key */
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28 while (lua_next(L, 1)) {
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29 lua_pop(L, 1); /* remove value */
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30 if (lua_type(L, -1) == LUA_TNUMBER) {
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31 lua_Number v = lua_tonumber(L, -1);
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32 if (v > max) max = v;
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33 }
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34 }
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35 lua_pushnumber(L, max);
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36 return 1;
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37 }
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38 #endif
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39
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40
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41 static int tinsert (lua_State *L) {
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42 int e = aux_getn(L, 1) + 1; /* first empty element */
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43 int pos; /* where to insert new element */
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44 switch (lua_gettop(L)) {
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45 case 2: { /* called with only 2 arguments */
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46 pos = e; /* insert new element at the end */
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47 break;
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48 }
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49 case 3: {
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50 int i;
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51 pos = luaL_checkint(L, 2); /* 2nd argument is the position */
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52 if (pos > e) e = pos; /* `grow' array if necessary */
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53 for (i = e; i > pos; i--) { /* move up elements */
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54 lua_rawgeti(L, 1, i-1);
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55 lua_rawseti(L, 1, i); /* t[i] = t[i-1] */
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56 }
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57 break;
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58 }
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59 default: {
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60 return luaL_error(L, "wrong number of arguments to " LUA_QL("insert"));
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61 }
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62 }
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63 lua_rawseti(L, 1, pos); /* t[pos] = v */
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64 return 0;
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65 }
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66
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67
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68 static int tremove (lua_State *L) {
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69 int e = aux_getn(L, 1);
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70 int pos = luaL_optint(L, 2, e);
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71 if (!(1 <= pos && pos <= e)) /* position is outside bounds? */
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72 return 0; /* nothing to remove */
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73 lua_rawgeti(L, 1, pos); /* result = t[pos] */
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74 for ( ;pos<e; pos++) {
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75 lua_rawgeti(L, 1, pos+1);
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76 lua_rawseti(L, 1, pos); /* t[pos] = t[pos+1] */
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77 }
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78 lua_pushnil(L);
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79 lua_rawseti(L, 1, e); /* t[e] = nil */
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80 return 1;
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81 }
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82
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83
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84 static void addfield (lua_State *L, luaL_Buffer *b, int i) {
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85 lua_rawgeti(L, 1, i);
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86 if (!lua_isstring(L, -1))
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87 luaL_error(L, "invalid value (%s) at index %d in table for "
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88 LUA_QL("concat"), luaL_typename(L, -1), i);
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89 luaL_addvalue(b);
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90 }
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91
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92
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93 static int tconcat (lua_State *L) {
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94 luaL_Buffer b;
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95 size_t lsep;
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96 int i, last;
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97 const char *sep = luaL_optlstring(L, 2, "", &lsep);
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98 luaL_checktype(L, 1, LUA_TTABLE);
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99 i = luaL_optint(L, 3, 1);
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100 last = luaL_opt(L, luaL_checkint, 4, luaL_len(L, 1));
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101 luaL_buffinit(L, &b);
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102 for (; i < last; i++) {
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103 addfield(L, &b, i);
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104 luaL_addlstring(&b, sep, lsep);
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105 }
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106 if (i == last) /* add last value (if interval was not empty) */
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107 addfield(L, &b, i);
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108 luaL_pushresult(&b);
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109 return 1;
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110 }
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111
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112
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113 /*
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114 ** {======================================================
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115 ** Pack/unpack
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116 ** =======================================================
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117 */
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118
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119 static int pack (lua_State *L) {
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120 int n = lua_gettop(L); /* number of elements to pack */
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121 lua_createtable(L, n, 1); /* create result table */
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122 lua_pushinteger(L, n);
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123 lua_setfield(L, -2, "n"); /* t.n = number of elements */
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124 if (n > 0) { /* at least one element? */
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125 int i;
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126 lua_pushvalue(L, 1);
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127 lua_rawseti(L, -2, 1); /* insert first element */
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128 lua_replace(L, 1); /* move table into index 1 */
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129 for (i = n; i >= 2; i--) /* assign other elements */
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130 lua_rawseti(L, 1, i);
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131 }
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132 return 1; /* return table */
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133 }
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134
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135
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136 static int unpack (lua_State *L) {
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137 int i, e, n;
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138 luaL_checktype(L, 1, LUA_TTABLE);
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139 i = luaL_optint(L, 2, 1);
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140 e = luaL_opt(L, luaL_checkint, 3, luaL_len(L, 1));
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141 if (i > e) return 0; /* empty range */
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142 n = e - i + 1; /* number of elements */
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143 if (n <= 0 || !lua_checkstack(L, n)) /* n <= 0 means arith. overflow */
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144 return luaL_error(L, "too many results to unpack");
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145 lua_rawgeti(L, 1, i); /* push arg[i] (avoiding overflow problems) */
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146 while (i++ < e) /* push arg[i + 1...e] */
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147 lua_rawgeti(L, 1, i);
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148 return n;
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149 }
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150
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151 /* }====================================================== */
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152
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153
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154
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155 /*
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156 ** {======================================================
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157 ** Quicksort
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158 ** (based on `Algorithms in MODULA-3', Robert Sedgewick;
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159 ** Addison-Wesley, 1993.)
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160 ** =======================================================
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161 */
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162
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163
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164 static void set2 (lua_State *L, int i, int j) {
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165 lua_rawseti(L, 1, i);
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166 lua_rawseti(L, 1, j);
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167 }
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168
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169 static int sort_comp (lua_State *L, int a, int b) {
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170 if (!lua_isnil(L, 2)) { /* function? */
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171 int res;
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172 lua_pushvalue(L, 2);
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173 lua_pushvalue(L, a-1); /* -1 to compensate function */
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174 lua_pushvalue(L, b-2); /* -2 to compensate function and `a' */
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175 lua_call(L, 2, 1);
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176 res = lua_toboolean(L, -1);
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177 lua_pop(L, 1);
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178 return res;
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179 }
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180 else /* a < b? */
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181 return lua_compare(L, a, b, LUA_OPLT);
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182 }
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183
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184 static void auxsort (lua_State *L, int l, int u) {
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185 while (l < u) { /* for tail recursion */
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186 int i, j;
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187 /* sort elements a[l], a[(l+u)/2] and a[u] */
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188 lua_rawgeti(L, 1, l);
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189 lua_rawgeti(L, 1, u);
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190 if (sort_comp(L, -1, -2)) /* a[u] < a[l]? */
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191 set2(L, l, u); /* swap a[l] - a[u] */
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192 else
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193 lua_pop(L, 2);
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194 if (u-l == 1) break; /* only 2 elements */
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195 i = (l+u)/2;
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196 lua_rawgeti(L, 1, i);
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197 lua_rawgeti(L, 1, l);
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198 if (sort_comp(L, -2, -1)) /* a[i]<a[l]? */
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199 set2(L, i, l);
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200 else {
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201 lua_pop(L, 1); /* remove a[l] */
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202 lua_rawgeti(L, 1, u);
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203 if (sort_comp(L, -1, -2)) /* a[u]<a[i]? */
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204 set2(L, i, u);
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205 else
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206 lua_pop(L, 2);
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207 }
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208 if (u-l == 2) break; /* only 3 elements */
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209 lua_rawgeti(L, 1, i); /* Pivot */
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210 lua_pushvalue(L, -1);
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211 lua_rawgeti(L, 1, u-1);
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212 set2(L, i, u-1);
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213 /* a[l] <= P == a[u-1] <= a[u], only need to sort from l+1 to u-2 */
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214 i = l; j = u-1;
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215 for (;;) { /* invariant: a[l..i] <= P <= a[j..u] */
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216 /* repeat ++i until a[i] >= P */
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217 while (lua_rawgeti(L, 1, ++i), sort_comp(L, -1, -2)) {
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218 if (i>=u) luaL_error(L, "invalid order function for sorting");
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219 lua_pop(L, 1); /* remove a[i] */
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220 }
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221 /* repeat --j until a[j] <= P */
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222 while (lua_rawgeti(L, 1, --j), sort_comp(L, -3, -1)) {
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223 if (j<=l) luaL_error(L, "invalid order function for sorting");
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224 lua_pop(L, 1); /* remove a[j] */
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225 }
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226 if (j<i) {
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227 lua_pop(L, 3); /* pop pivot, a[i], a[j] */
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228 break;
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229 }
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230 set2(L, i, j);
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231 }
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232 lua_rawgeti(L, 1, u-1);
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233 lua_rawgeti(L, 1, i);
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234 set2(L, u-1, i); /* swap pivot (a[u-1]) with a[i] */
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235 /* a[l..i-1] <= a[i] == P <= a[i+1..u] */
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236 /* adjust so that smaller half is in [j..i] and larger one in [l..u] */
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237 if (i-l < u-i) {
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238 j=l; i=i-1; l=i+2;
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239 }
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240 else {
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241 j=i+1; i=u; u=j-2;
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242 }
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243 auxsort(L, j, i); /* call recursively the smaller one */
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244 } /* repeat the routine for the larger one */
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245 }
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246
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247 static int sort (lua_State *L) {
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248 int n = aux_getn(L, 1);
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249 luaL_checkstack(L, 40, ""); /* assume array is smaller than 2^40 */
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250 if (!lua_isnoneornil(L, 2)) /* is there a 2nd argument? */
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251 luaL_checktype(L, 2, LUA_TFUNCTION);
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252 lua_settop(L, 2); /* make sure there is two arguments */
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253 auxsort(L, 1, n);
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254 return 0;
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255 }
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256
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257 /* }====================================================== */
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258
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259
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260 static const luaL_Reg tab_funcs[] = {
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261 {"concat", tconcat},
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262 #if defined(LUA_COMPAT_MAXN)
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263 {"maxn", maxn},
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264 #endif
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265 {"insert", tinsert},
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266 {"pack", pack},
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267 {"unpack", unpack},
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268 {"remove", tremove},
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269 {"sort", sort},
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270 {NULL, NULL}
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271 };
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272
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273
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274 LUAMOD_API int luaopen_table (lua_State *L) {
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275 luaL_newlib(L, tab_funcs);
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276 #if defined(LUA_COMPAT_UNPACK)
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277 /* _G.unpack = table.unpack */
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278 lua_getfield(L, -1, "unpack");
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279 lua_setglobal(L, "unpack");
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280 #endif
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281 return 1;
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282 }
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283
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