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- added SGCommandState class so that commands can compile and save

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copies of their arguments
- modified prototype for command functions -- they now take a pointer
  to a pointer of an SGCommandState object (which they will normally
  subclass) so that they can cache state between invocations
- commented out convenience execute methods until they're actually
  needed
This commit is contained in:
curt 2001-06-28 21:53:10 +00:00
parent a406a3c00b
commit be4fd56660
1 changed files with 133 additions and 90 deletions
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223
simgear/misc/commands.hxx
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@ -24,15 +24,55 @@ SG_USING_STD(map);
SG_USING_STD(vector);
/**
* Stored state for a command.
*
* <p>This class allows a command to cache parts of its state between
* invocations with the same parameters. Nearly every command that
* actually uses this will subclass it in some way. The command
* allocates the structure, but it is up to the caller to delete it
* when it is no longer necessary, unless the command deletes it
* and replaces the value with 0 or another command-state object
* first.</p>
*
* <p>Note that this class is for caching only; all of the information
* in it must be recoverable by other means, since the state could
* arbitrarily disappear between invocations if the caller decides to
* delete it.</p>
*
* <p>By default, the command state includes a place to keep a copy of
* the parameters.</p>
*
* @author David Megginson, david@megginson.com
*/
class SGCommandState
{
public:
SGCommandState ();
SGCommandState (const SGPropertyNode * args);
virtual ~SGCommandState ();
virtual void setArgs (const SGPropertyNode * args);
virtual const SGPropertyNode * getArgs () const { return _args; }
private:
SGPropertyNode * _args;
};
/**
* Manage commands.
*
* <p>This class allows the application to register and unregister
* commands, and provides shortcuts for executing them. Commands
* are simple functions that take a const pointer to an SGPropertyNode
* as an argument and return a bool value indicating success or failure.
* The property node may be ignored, or it may contain values that
* the command uses as parameters.</p>
* commands, and provides shortcuts for executing them. Commands are
* simple functions that take a const pointer to an SGPropertyNode and
* a pointer to a pointer variable (which should be 0 initially) where
* the function can store compiled copies of its arguments, etc. to
* avoid expensive recalculations. If the command deletes the
* SGCommandState, it must replace it with a new pointer or 0;
* otherwise, the caller is free to delete and zero the pointer at any
* time and the command will start fresh with the next invocation.
* The command must return a bool value indicating success or failure.
* The property node may be ignored, or it may contain values that the
* command uses as parameters.</p>
*
* <p>There are convenience methods for invoking a command function
* with no arguments or with a single, primitive argument.</p>
@ -46,7 +86,8 @@ public:
/**
* Type for a command function.
*/
typedef bool (*command_t) (const SGPropertyNode * arg);
typedef bool (*command_t) (const SGPropertyNode * arg,
SGCommandState ** state);
/**
@ -105,104 +146,106 @@ public:
* @return true if the command is present and executes successfully,
* false otherwise.
*/
virtual bool execute (const string &name, const SGPropertyNode * arg) const;
virtual bool execute (const string &name,
const SGPropertyNode * arg,
SGCommandState ** state) const;
/**
* Execute a command with no argument.
*
* The command function will receive a pointer to a property node
* with no value and no children.
*
* @param name The name of the command.
* @return true if the command is present and executes successfully,
* false otherwise.
*/
virtual bool execute (const string &name) const;
// /**
// * Execute a command with no argument.
// *
// * The command function will receive a pointer to a property node
// * with no value and no children.
// *
// * @param name The name of the command.
// * @return true if the command is present and executes successfully,
// * false otherwise.
// */
// virtual bool execute (const string &name) const;
/**
* Execute a command with a single bool argument.
*
* The command function will receive a pointer to a property node
* with a bool value and no children.
*
* @param name The name of the command.
* @param arg The bool argument to the command.
* @return true if the command is present and executes successfully,
* false otherwise.
*/
virtual bool execute (const string &name, bool arg) const;
// /**
// * Execute a command with a single bool argument.
// *
// * The command function will receive a pointer to a property node
// * with a bool value and no children.
// *
// * @param name The name of the command.
// * @param arg The bool argument to the command.
// * @return true if the command is present and executes successfully,
// * false otherwise.
// */
// virtual bool execute (const string &name, bool arg) const;
/**
* Execute a command with a single int argument.
*
* The command function will receive a pointer to a property node
* with a int value and no children.
*
* @param name The name of the command.
* @param arg The int argument to the command.
* @return true if the command is present and executes successfully,
* false otherwise.
*/
virtual bool execute (const string &name, int arg) const;
// /**
// * Execute a command with a single int argument.
// *
// * The command function will receive a pointer to a property node
// * with a int value and no children.
// *
// * @param name The name of the command.
// * @param arg The int argument to the command.
// * @return true if the command is present and executes successfully,
// * false otherwise.
// */
// virtual bool execute (const string &name, int arg) const;
/**
* Execute a command with a single long argument.
*
* The command function will receive a pointer to a property node
* with a long value and no children.
*
* @param name The name of the command.
* @param arg The long argument to the command.
* @return true if the command is present and executes successfully,
* false otherwise.
*/
virtual bool execute (const string &name, long arg) const;
// /**
// * Execute a command with a single long argument.
// *
// * The command function will receive a pointer to a property node
// * with a long value and no children.
// *
// * @param name The name of the command.
// * @param arg The long argument to the command.
// * @return true if the command is present and executes successfully,
// * false otherwise.
// */
// virtual bool execute (const string &name, long arg) const;
/**
* Execute a command with a single float argument.
*
* The command function will receive a pointer to a property node
* with a float value and no children.
*
* @param name The name of the command.
* @param arg The float argument to the command.
* @return true if the command is present and executes successfully,
* false otherwise.
*/
virtual bool execute (const string &name, float arg) const;
// /**
// * Execute a command with a single float argument.
// *
// * The command function will receive a pointer to a property node
// * with a float value and no children.
// *
// * @param name The name of the command.
// * @param arg The float argument to the command.
// * @return true if the command is present and executes successfully,
// * false otherwise.
// */
// virtual bool execute (const string &name, float arg) const;
/**
* Execute a command with a single double argument.
*
* The command function will receive a pointer to a property node
* with a double value and no children.
*
* @param name The name of the command.
* @param arg The double argument to the command.
* @return true if the command is present and executes successfully,
* false otherwise.
*/
virtual bool execute (const string &name, double arg) const;
// /**
// * Execute a command with a single double argument.
// *
// * The command function will receive a pointer to a property node
// * with a double value and no children.
// *
// * @param name The name of the command.
// * @param arg The double argument to the command.
// * @return true if the command is present and executes successfully,
// * false otherwise.
// */
// virtual bool execute (const string &name, double arg) const;
/**
* Execute a command with a single string argument.
*
* The command function will receive a pointer to a property node
* with a string value and no children.
*
* @param name The name of the command.
* @param arg The string argument to the command.
* @return true if the command is present and executes successfully,
* false otherwise.
*/
virtual bool execute (const string &name, string arg) const;
// /**
// * Execute a command with a single string argument.
// *
// * The command function will receive a pointer to a property node
// * with a string value and no children.
// *
// * @param name The name of the command.
// * @param arg The string argument to the command.
// * @return true if the command is present and executes successfully,
// * false otherwise.
// */
// virtual bool execute (const string &name, string arg) const;
private: