# Script builder helper

Path: /sdk/add_on/scriptbuilder/

This class is a helper class for loading and building scripts, with a basic pre-processor that supports conditional compilation, include directives, and metadata declarations.

## Public C++ interface

    class CScriptBuilder
    {
    public:
      // Load and build a script file from disk
      int BuildScriptFromFile(asIScriptEngine *engine,
                              const char      *module,
                              const char      *filename);

      // Build a script file from a memory buffer
      int BuildScriptFromMemory(asIScriptEngine *engine,
                                const char      *module,
                                const char      *script,
                                const char      *sectionname = "");

      // Add a pre-processor define for conditional compilation
      void DefineWord(const char *word);

      // Get metadata declared for class types and interfaces
      const char *GetMetadataStringForType(int typeId);

      // Get metadata declared for functions
      const char *GetMetadataStringForFunc(int funcId);

      // Get metadata declared for global variables
      const char *GetMetadataStringForVar(int varIdx);
    };

## Include directives

Example script with include directive:

      #include "commonfuncs.as"

      void main()
      {
        // Call a function from the included file
        CommonFunc();
      }

## Conditional programming

The builder supports conditional programming through the #if/#endif preprocessor directives. The application may define a word with a call to DefineWord(), then the scripts may check for this definition in the code in order to include/exclude parts of the code.

This is especially useful when scripts are shared between different binaries, for example, in a client/server application.

Example script with conditional compilation:

      class CObject
      {
        void Process()
        {
      #if SERVER
          // Do some server specific processing
      #endif

      #if CLIENT
          // Do some client specific processing
      #endif

          // Do some common processing
        }
      }

## Metadata in scripts

Metadata can be added before script class, interface, function, and global variable declarations. The metadata is removed from the script by the builder class and stored for post build lookup by the type id, function id, or variable index.

Exactly what the metadata looks like is up to the application. The builder class doesn't impose any rules, except that the metadata should be added between brackets []. After the script has been built the application can obtain the metadata strings and interpret them as it sees fit.

Example script with metadata:

      [factory func = CreateOgre,
       editable: myPosition,
       editable: myStrength [10, 100]]
      class COgre
      {
        vector3 myPosition;
        int     myStrength;
      }

      [factory]
      COgre @CreateOgre()
      {
        return @COgre();
      }

Example usage:

    CScriptBuilder builder;
    int r = builder.BuildScriptFromMemory(engine, "my module", script);
    if( r >= 0 )
    {
      // Find global variables that have been marked as editable by user
      int count = engine->GetGlobalVarCount("my module");
      for( int n = 0; n < count; n++ )
      {
        string metadata = builder.GetMetadataStringForVar(n);
        if( metadata == "editable" )
        {
          // Show the global variable in a GUI
          ...
        }
      }
    }