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1 ------------------------------------------------------------------------------
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2 -- --
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3 -- GNAT RUN-TIME COMPONENTS --
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4 -- --
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5 -- A D A . S T R I N G S . U T F _ E N C O D I N G --
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6 -- --
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7 -- B o d y --
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8 -- --
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131
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9 -- Copyright (C) 2010-2018, Free Software Foundation, Inc. --
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111
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10 -- --
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11 -- GNAT is free software; you can redistribute it and/or modify it under --
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12 -- terms of the GNU General Public License as published by the Free Soft- --
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13 -- ware Foundation; either version 3, or (at your option) any later ver- --
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14 -- sion. GNAT is distributed in the hope that it will be useful, but WITH- --
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15 -- OUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY --
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16 -- or FITNESS FOR A PARTICULAR PURPOSE. --
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17 -- --
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18 -- As a special exception under Section 7 of GPL version 3, you are granted --
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19 -- additional permissions described in the GCC Runtime Library Exception, --
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20 -- version 3.1, as published by the Free Software Foundation. --
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21 -- --
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22 -- You should have received a copy of the GNU General Public License and --
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23 -- a copy of the GCC Runtime Library Exception along with this program; --
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24 -- see the files COPYING3 and COPYING.RUNTIME respectively. If not, see --
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25 -- <http://www.gnu.org/licenses/>. --
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26 -- --
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27 -- GNAT was originally developed by the GNAT team at New York University. --
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28 -- Extensive contributions were provided by Ada Core Technologies Inc. --
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29 -- --
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30 ------------------------------------------------------------------------------
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31
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32 package body Ada.Strings.UTF_Encoding is
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33 use Interfaces;
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34
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35 --------------
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36 -- Encoding --
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37 --------------
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38
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39 function Encoding
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40 (Item : UTF_String;
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41 Default : Encoding_Scheme := UTF_8) return Encoding_Scheme
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42 is
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43 begin
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44 if Item'Length >= 2 then
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45 if Item (Item'First .. Item'First + 1) = BOM_16BE then
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46 return UTF_16BE;
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47
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48 elsif Item (Item'First .. Item'First + 1) = BOM_16LE then
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49 return UTF_16LE;
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50
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51 elsif Item'Length >= 3
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52 and then Item (Item'First .. Item'First + 2) = BOM_8
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53 then
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54 return UTF_8;
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55 end if;
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56 end if;
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57
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58 return Default;
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59 end Encoding;
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60
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61 -----------------
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62 -- From_UTF_16 --
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63 -----------------
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64
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65 function From_UTF_16
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66 (Item : UTF_16_Wide_String;
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67 Output_Scheme : UTF_XE_Encoding;
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68 Output_BOM : Boolean := False) return UTF_String
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69 is
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70 BSpace : constant Natural := 2 * Boolean'Pos (Output_BOM);
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71 Result : UTF_String (1 .. 2 * Item'Length + BSpace);
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72 Len : Natural;
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73 C : Unsigned_16;
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74 Iptr : Natural;
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75
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76 begin
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77 if Output_BOM then
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78 Result (1 .. 2) :=
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79 (if Output_Scheme = UTF_16BE then BOM_16BE else BOM_16LE);
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80 Len := 2;
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81 else
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82 Len := 0;
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83 end if;
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84
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85 -- Skip input BOM
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86
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87 Iptr := Item'First;
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88
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89 if Iptr <= Item'Last and then Item (Iptr) = BOM_16 (1) then
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90 Iptr := Iptr + 1;
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91 end if;
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92
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93 -- UTF-16BE case
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94
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95 if Output_Scheme = UTF_16BE then
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96 while Iptr <= Item'Last loop
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97 C := To_Unsigned_16 (Item (Iptr));
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98 Result (Len + 1) := Character'Val (Shift_Right (C, 8));
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99 Result (Len + 2) := Character'Val (C and 16#00_FF#);
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100 Len := Len + 2;
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101 Iptr := Iptr + 1;
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102 end loop;
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103
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104 -- UTF-16LE case
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105
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106 else
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107 while Iptr <= Item'Last loop
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108 C := To_Unsigned_16 (Item (Iptr));
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109 Result (Len + 1) := Character'Val (C and 16#00_FF#);
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110 Result (Len + 2) := Character'Val (Shift_Right (C, 8));
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111 Len := Len + 2;
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112 Iptr := Iptr + 1;
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113 end loop;
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114 end if;
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115
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116 return Result (1 .. Len);
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117 end From_UTF_16;
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118
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119 --------------------------
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120 -- Raise_Encoding_Error --
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121 --------------------------
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122
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123 procedure Raise_Encoding_Error (Index : Natural) is
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124 Val : constant String := Index'Img;
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125 begin
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126 raise Encoding_Error with
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127 "bad input at Item (" & Val (Val'First + 1 .. Val'Last) & ')';
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128 end Raise_Encoding_Error;
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129
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130 ---------------
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131 -- To_UTF_16 --
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132 ---------------
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133
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134 function To_UTF_16
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135 (Item : UTF_String;
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136 Input_Scheme : UTF_XE_Encoding;
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137 Output_BOM : Boolean := False) return UTF_16_Wide_String
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138 is
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139 Result : UTF_16_Wide_String (1 .. Item'Length / 2 + 1);
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140 Len : Natural;
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141 Iptr : Natural;
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142
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143 begin
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144 if Item'Length mod 2 /= 0 then
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145 raise Encoding_Error with "UTF-16BE/LE string has odd length";
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146 end if;
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147
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148 -- Deal with input BOM, skip if OK, error if bad BOM
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149
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150 Iptr := Item'First;
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151
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152 if Item'Length >= 2 then
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153 if Item (Iptr .. Iptr + 1) = BOM_16BE then
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154 if Input_Scheme = UTF_16BE then
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155 Iptr := Iptr + 2;
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156 else
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157 Raise_Encoding_Error (Iptr);
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158 end if;
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159
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160 elsif Item (Iptr .. Iptr + 1) = BOM_16LE then
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161 if Input_Scheme = UTF_16LE then
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162 Iptr := Iptr + 2;
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163 else
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164 Raise_Encoding_Error (Iptr);
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165 end if;
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166
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167 elsif Item'Length >= 3 and then Item (Iptr .. Iptr + 2) = BOM_8 then
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168 Raise_Encoding_Error (Iptr);
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169 end if;
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170 end if;
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171
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172 -- Output BOM if specified
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173
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174 if Output_BOM then
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175 Result (1) := BOM_16 (1);
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176 Len := 1;
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177 else
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178 Len := 0;
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179 end if;
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180
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181 -- UTF-16BE case
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182
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183 if Input_Scheme = UTF_16BE then
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184 while Iptr < Item'Last loop
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185 Len := Len + 1;
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186 Result (Len) :=
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187 Wide_Character'Val
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188 (Character'Pos (Item (Iptr)) * 256 +
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189 Character'Pos (Item (Iptr + 1)));
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190 Iptr := Iptr + 2;
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191 end loop;
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192
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193 -- UTF-16LE case
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194
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195 else
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196 while Iptr < Item'Last loop
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197 Len := Len + 1;
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198 Result (Len) :=
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199 Wide_Character'Val
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200 (Character'Pos (Item (Iptr)) +
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201 Character'Pos (Item (Iptr + 1)) * 256);
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202 Iptr := Iptr + 2;
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203 end loop;
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204 end if;
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205
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206 return Result (1 .. Len);
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207 end To_UTF_16;
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208
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209 end Ada.Strings.UTF_Encoding;
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