Source/cmIfCommand.h

   1 /*=========================================================================
   2
   3   Program:   CMake - Cross-Platform Makefile Generator
   4   Module:    $RCSfile: cmIfCommand.h,v $
   5   Language:  C++
   6   Date:      $Date: 2009-09-14 17:42:04 $
   7   Version:   $Revision: 1.57 $
   8
   9   Copyright (c) 2002 Kitware, Inc., Insight Consortium.  All rights reserved.
  10   See Copyright.txt or http://www.cmake.org/HTML/Copyright.html for details.
  11
  12      This software is distributed WITHOUT ANY WARRANTY; without even
  13      the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR
  14      PURPOSE.  See the above copyright notices for more information.
  15
  16 =========================================================================*/
  17 #ifndef cmIfCommand_h
  18 #define cmIfCommand_h
  19
  20 #include "cmCommand.h"
  21 #include "cmFunctionBlocker.h"
  22
  23 /** \class cmIfFunctionBlocker
  24  * \brief subclass of function blocker
  25  *
  26  *
  27  */
  28 class cmIfFunctionBlocker : public cmFunctionBlocker
  29 {
  30 public:
  31   cmIfFunctionBlocker() {
  32     this->HasRun = false; this->ScopeDepth = 0; }
  33   virtual ~cmIfFunctionBlocker() {}
  34   virtual bool IsFunctionBlocked(const cmListFileFunction& lff,
  35                                  cmMakefile &mf,
  36                                  cmExecutionStatus &);
  37   virtual bool ShouldRemove(const cmListFileFunction& lff,
  38                             cmMakefile &mf);
  39
  40   std::vector<cmListFileArgument> Args;
  41   std::vector<cmListFileFunction> Functions;
  42   bool IsBlocking;
  43   bool HasRun;
  44   unsigned int ScopeDepth;
  45 };
  46
  47 /** \class cmIfCommand
  48  * \brief starts an if block
  49  *
  50  * cmIfCommand starts an if block
  51  */
  52 class cmIfCommand : public cmCommand
  53 {
  54 public:
  55   /**
  56    * This is a virtual constructor for the command.
  57    */
  58   virtual cmCommand* Clone()
  59     {
  60     return new cmIfCommand;
  61     }
  62
  63   /**
  64    * This overrides the default InvokeInitialPass implementation.
  65    * It records the arguments before expansion.
  66    */
  67   virtual bool InvokeInitialPass(const std::vector<cmListFileArgument>& args,
  68                                  cmExecutionStatus &);
  69
  70   /**
  71    * This is called when the command is first encountered in
  72    * the CMakeLists.txt file.
  73    */
  74   virtual bool InitialPass(std::vector<std::string> const&,
  75                            cmExecutionStatus &) { return false;};
  76
  77   /**
  78    * The name of the command as specified in CMakeList.txt.
  79    */
  80   virtual const char* GetName() { return "if";}
  81
  82   /**
  83    * Succinct documentation.
  84    */
  85   virtual const char* GetTerseDocumentation()
  86     {
  87     return "Conditionally execute a group of commands.";
  88     }
  89
  90   /**
  91    * This determines if the command is invoked when in script mode.
  92    */
  93   virtual bool IsScriptable() { return true; }
  94
  95   /**
  96    * More documentation.
  97    */
  98   virtual const char* GetFullDocumentation()
  99     {
 100     return
 101       "  if(expression)\n"
 102       "    # then section.\n"
 103       "    COMMAND1(ARGS ...)\n"
 104       "    COMMAND2(ARGS ...)\n"
 105       "    ...\n"
 106       "  elseif(expression2)\n"
 107       "    # elseif section.\n"
 108       "    COMMAND1(ARGS ...)\n"
 109       "    COMMAND2(ARGS ...)\n"
 110       "    ...\n"
 111       "  else(expression)\n"
 112       "    # else section.\n"
 113       "    COMMAND1(ARGS ...)\n"
 114       "    COMMAND2(ARGS ...)\n"
 115       "    ...\n"
 116       "  endif(expression)\n"
 117       "Evaluates the given expression.  If the result is true, the commands "
 118       "in the THEN section are invoked.  Otherwise, the commands in the "
 119       "else section are invoked.  The elseif and else sections are "
 120       "optional. You may have multiple elseif clauses. Note that "
 121       "the expression in the else and endif clause is optional. Long "
 122       "expressions can be used and there is a traditional order of "
 123       "precedence. "
 124       "Parenthetical expressions are evaluated first followed by unary "
 125       "operators such as EXISTS, COMMAND, and DEFINED. "
 126       "Then any EQUAL, LESS, GREATER, STRLESS, STRGREATER, STREQUAL, MATCHES "
 127       "will be evaluated. Then NOT operators and finally AND, OR operators "
 128       "will be evaluated. Possible expressions are:\n"
 129       "  if(variable)\n"
 130       "True if the variable's value is not empty, 0, N, NO, OFF, FALSE, "
 131       "NOTFOUND, or <variable>-NOTFOUND.\n"
 132       "  if(NOT variable)\n"
 133       "True if the variable's value is empty, 0, N, NO, OFF, FALSE, "
 134       "NOTFOUND, or <variable>-NOTFOUND.\n"
 135       "  if(variable1 AND variable2)\n"
 136       "True if both variables would be considered true individually.\n"
 137       "  if(variable1 OR variable2)\n"
 138       "True if either variable would be considered true individually.\n"
 139       "  if(COMMAND command-name)\n"
 140       "True if the given name is a command, macro or function that can be "
 141       "invoked.\n"
 142       "  if(POLICY policy-id)\n"
 143       "True if the given name is an existing policy "
 144       "(of the form CMP<NNNN>).\n"
 145       "  if(TARGET target-name)\n"
 146       "True if the given name is an existing target, built or imported.\n"
 147       "  if(EXISTS file-name)\n"
 148       "  if(EXISTS directory-name)\n"
 149       "True if the named file or directory exists.  "
 150       "Behavior is well-defined only for full paths.\n"
 151       "  if(file1 IS_NEWER_THAN file2)\n"
 152       "True if file1 is newer than file2 or if one of the two files "
 153       "doesn't exist. "
 154       "Behavior is well-defined only for full paths.\n"
 155       "  if(IS_DIRECTORY directory-name)\n"
 156       "True if the given name is a directory.  "
 157       "Behavior is well-defined only for full paths.\n"
 158       "  if(IS_ABSOLUTE path)\n"
 159       "True if the given path is an absolute path.\n"
 160       "  if(variable MATCHES regex)\n"
 161       "  if(string MATCHES regex)\n"
 162       "True if the given string or variable's value matches the given "
 163       "regular expression.\n"
 164       "  if(variable LESS number)\n"
 165       "  if(string LESS number)\n"
 166       "  if(variable GREATER number)\n"
 167       "  if(string GREATER number)\n"
 168       "  if(variable EQUAL number)\n"
 169       "  if(string EQUAL number)\n"
 170       "True if the given string or variable's value is a valid number and "
 171       "the inequality or equality is true.\n"
 172       "  if(variable STRLESS string)\n"
 173       "  if(string STRLESS string)\n"
 174       "  if(variable STRGREATER string)\n"
 175       "  if(string STRGREATER string)\n"
 176       "  if(variable STREQUAL string)\n"
 177       "  if(string STREQUAL string)\n"
 178       "True if the given string or variable's value is lexicographically "
 179       "less (or greater, or equal) than the string or variable on the right.\n"
 180       "  if(version1 VERSION_LESS version2)\n"
 181       "  if(version1 VERSION_EQUAL version2)\n"
 182       "  if(version1 VERSION_GREATER version2)\n"
 183       "Component-wise integer version number comparison (version format is "
 184       "major[.minor[.patch[.tweak]]]).\n"
 185       "  if(DEFINED variable)\n"
 186       "True if the given variable is defined. It does not matter if the "
 187       "variable is true or false just if it has been set.\n"
 188       "  if((expression) AND (expression OR (expression)))\n"
 189       "The expressions inside the parenthesis are evaluated first and "
 190       "then the remaining expression is evaluated as in the previous "
 191       "examples. Where there are nested parenthesis the innermost are "
 192       "evaluated as part of evaluating the expression "
 193       "that contains them."
 194       "\n"
 195
 196       "The if statement was written fairly early in CMake's history "
 197       "and it has some convenience features that are worth covering. "
 198       "The if statement reduces operations until there is "
 199       "a single remaining value, at that point if the case "
 200       "insensitive value is: ON, 1, YES, TRUE, Y it returns true, if "
 201       "it is OFF, 0, NO, FALSE, N, NOTFOUND, *-NOTFOUND, IGNORE it "
 202       "will return false. \n"
 203
 204       "This is fairly reasonable. The convenience feature that sometimes "
 205       "throws new authors is how CMake handles values that do not "
 206       "match the true or false list. Those values are treated as "
 207       "variables and are dereferenced even though they do not have "
 208       "the required ${} syntax. This means that if you write\n"
 209
 210       "  if (boobah)\n"
 211
 212       "CMake will treat it as if you wrote \n"
 213
 214       "  if (${boobah})\n"
 215
 216       "likewise if you write \n"
 217
 218       "  if (fubar AND sol)\n"
 219
 220       "CMake will conveniently treat it as \n"
 221
 222       "  if (\"${fubar}\" AND \"${sol}\")\n"
 223
 224       "The later is really the correct way to write it, but the "
 225       "former will work as well. Only some operations in the if "
 226       "statement have this special handling of arguments. The "
 227       "specific details follow: \n"
 228
 229       "1) The left hand argument to MATCHES is first checked to see "
 230       "if it is a defined variable, if so the variable's value is "
 231       "used, otherwise the original value is used. \n"
 232
 233       "2) If the left hand argument to MATCHES is missing it returns "
 234       "false without error \n"
 235
 236       "3) Both left and right hand arguments to LESS GREATER EQUAL "
 237       "are independently tested to see if they are defined variables, "
 238       "if so their defined values are used otherwise the original "
 239       "value is used. \n"
 240
 241       "4) Both left and right hand arguments to STRLESS STREQUAL "
 242       "STRGREATER are independently tested to see if they are defined "
 243       "variables, if so their defined values are used otherwise the "
 244       "original value is used. \n"
 245
 246       "5) Both left and right hand argumemnts to VERSION_LESS "
 247       "VERSION_EQUAL VERSION_GREATER are independently tested to see "
 248       "if they are defined variables, if so their defined values are "
 249       "used otherwise the original value is used. \n"
 250
 251       "6) The right hand argument to NOT is tested to see if it is a "
 252       "boolean constant, if so the value is used, otherwise it is "
 253       "assumed to be a variable and it is dereferenced. \n"
 254
 255       "7) The left and right hand arguments to AND OR are "
 256       "independently tested to see if they are boolean constants, if "
 257       "so they are used as such, otherwise they are assumed to be "
 258       "variables and are dereferenced. \n"
 259       ;
 260     }
 261
 262   // this is a shared function for both If and Else to determine if the
 263   // arguments were valid, and if so, was the response true. If there is
 264   // an error, the errorString will be set.
 265   static bool IsTrue(const std::vector<std::string> &args,
 266     std::string &errorString, cmMakefile *mf,
 267     cmake::MessageType &status);
 268
 269   // Get a definition from the makefile.  If it doesn't exist,
 270   // return the original string.
 271   static const char* GetVariableOrString(const char* str,
 272                                          const cmMakefile* mf);
 273
 274   cmTypeMacro(cmIfCommand, cmCommand);
 275 };
 276
 277
 278 #endif