/[svn]/linuxsampler/trunk/src/scriptvm/common.h

Diff of /linuxsampler/trunk/src/scriptvm/common.h

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-revision 2889 by schoenebeck,
Mon Apr 25 17:28:23 2016 UTC
+revision 3012 by schoenebeck,
Wed Oct 12 12:50:37 2016 UTC
 Line 160 
 namespace LinuxSampler {
           * @see exprType()
           */
          VMIntArrayExpr* asIntArray() const;
+         /**
+          * Returns true in case this expression can be considered to be a
+          * constant expression. A constant expression will retain the same
+          * value throughout the entire life time of a script and the
+          * expression's constant value may be evaluated already at script
+          * parse time, which may result in performance benefits during script
+          * runtime.
+          *
+          * @b NOTE: A constant expression is per se always also non modifyable.
+          * But a non modifyable expression may not necessarily be a constant
+          * expression!
+          *
+          * @see isModifyable()
+          */
+         virtual bool isConstExpr() const = 0;
+         /**
+          * Returns true in case this expression is allowed to be modified.
+          * If this method returns @c false then this expression must be handled
+          * as read-only expression, which means that assigning a new value to it
+          * is either not possible or not allowed.
+          *
+          * @b NOTE: A constant expression is per se always also non modifyable.
+          * But a non modifyable expression may not necessarily be a constant
+          * expression!
+          *
+          * @see isConstExpr()
+          */
+         bool isModifyable() const;
      };
      /** @brief Virtual machine integer expression
-Line 366 
 namespace LinuxSampler {
+Line 396 
 namespace LinuxSampler {
          virtual ExprType_t argType(int iArg) const = 0;
          /**
-          * This function is called by the parser to check whether arguments
+          * This method is called by the parser to check whether arguments
           * passed in scripts to this function are accepted by this function. If
           * a script calls this function with an argument's data type not
           * accepted by this function, the parser will throw a parser error. On
-Line 384 
 namespace LinuxSampler {
+Line 414 
 namespace LinuxSampler {
          virtual bool acceptsArgType(int iArg, ExprType_t type) const = 0;
          /**
+          * This method is called by the parser to check whether some arguments
+          * (and if yes which ones) passed to this script function will be
+          * modified by this script function. Most script functions simply use
+          * their arguments as inputs, that is they only read the argument's
+          * values. However some script function may also use passed
+          * argument(s) as output variables. In this case the function
+          * implementation must return @c true for the respective argument
+          * index here.
+          *
+          * @param iArg - index of the function argument in question
+          *               (must be between 0 .. maxAllowedArgs() - 1)
+          */
+         virtual bool modifiesArg(int iArg) const = 0;
+         /**
           * Implements the actual function execution. This exec() method is
           * called by the VM whenever this function implementation shall be
           * executed at script runtime. This method blocks until the function
-Line 423 
 namespace LinuxSampler {
+Line 468 
 namespace LinuxSampler {
      struct VMRelPtr {
          void** base; ///< Base pointer.
          int offset;  ///< Offset (in bytes) relative to base pointer.
+         bool readonly; ///< Whether the pointed data may be modified or just be read.
      };
      /** @brief Pointer to built-in VM integer variable (of C/C++ type int).
-Line 450 
 namespace LinuxSampler {
+Line 496 
 namespace LinuxSampler {
          VMIntRelPtr() {
              base   = NULL;
              offset = 0;
+             readonly = false;
          }
          VMIntRelPtr(const VMRelPtr& data) {
              base   = data.base;
              offset = data.offset;
+             readonly = false;
          }
          virtual int evalInt() { return *(int*)&(*(uint8_t**)base)[offset]; }
          virtual void assign(int i) { *(int*)&(*(uint8_t**)base)[offset] = i; }
-Line 536 
 namespace LinuxSampler {
+Line 584 
 namespace LinuxSampler {
      #define DECLARE_VMINT(basePtr, T_struct, T_member) ( \
          (VMRelPtr) {                                     \
              (void**) &basePtr,                           \
-             offsetof(T_struct, T_member)                 \
+             offsetof(T_struct, T_member),                \
+             false                                        \
          }                                                \
      )                                                    \
+     /**
+      * Same as DECLARE_VMINT(), but this one defines the VMIntRelPtr and
+      * VMInt8RelPtr structures to be of read-only type. That means the script
+      * parser will abort any script at parser time if the script is trying to
+      * modify such a read-only built-in variable.
+      *
+      * @b NOTE: this is only intended for built-in read-only variables that
+      * may change during runtime! If your built-in variable's data is rather
+      * already available at parser time and won't change during runtime, then
+      * you should rather register a built-in constant in your VM class instead!
+      *
+      * @see ScriptVM::builtInConstIntVariables()
+      */
+     #define DECLARE_VMINT_READONLY(basePtr, T_struct, T_member) ( \
+         (VMRelPtr) {                                          \
+             (void**) &basePtr,                                \
+             offsetof(T_struct, T_member),                     \
+             true                                              \
+         }                                                     \
+     )                                                         \
      /** @brief Built-in VM 8 bit integer array variable.
       *
       * Used for defining built-in integer array script variables (8 bit per
-Line 553 
 namespace LinuxSampler {
+Line 623 
 namespace LinuxSampler {
          VMInt8Array() : data(NULL), size(0) {}
      };
+     /** @brief Virtual machine script variable.
+      *
+      * Common interface for all variables accessed in scripts.
+      */
+     class VMVariable : virtual public VMExpr {
+     public:
+         /**
+          * Whether a script may modify the content of this variable by
+          * assigning a new value to it.
+          *
+          * @see isConstExpr(), assign()
+          */
+         virtual bool isAssignable() const = 0;
+         /**
+          * In case this variable is assignable, this method will be called to
+          * perform the value assignment to this variable with @a expr
+          * reflecting the new value to be assigned.
+          *
+          * @param expr - new value to be assigned to this variable
+          */
+         virtual void assignExpr(VMExpr* expr) = 0;
+     };
+     /** @brief Dynamically executed variable (abstract base class).
+      *
+      * Interface for the implementation of a dynamically generated content of
+      * a built-in script variable. Most built-in variables are simply pointers
+      * to some native location in memory. So when a script reads them, the
+      * memory location is simply read to get the value of the variable. A
+      * dynamic variable however is not simply a memory location. For each access
+      * to a dynamic variable some native code is executed to actually generate
+      * and provide the content (value) of this type of variable.
+      */
+     class VMDynVar : public VMVariable {
+     public:
+         /**
+          * Returns true in case this dynamic variable can be considered to be a
+          * constant expression. A constant expression will retain the same value
+          * throughout the entire life time of a script and the expression's
+          * constant value may be evaluated already at script parse time, which
+          * may result in performance benefits during script runtime.
+          *
+          * However due to the "dynamic" behavior of dynamic variables, almost
+          * all dynamic variables are probably not constant expressions. That's
+          * why this method returns @c false by default. If you are really sure
+          * that your dynamic variable implementation can be considered a
+          * constant expression then you may override this method and return
+          * @c true instead. Note that when you return @c true here, your
+          * dynamic variable will really just be executed once; and exectly
+          * already when the script is loaded!
+          *
+          * As an example you may implement a "constant" built-in dynamic
+          * variable that checks for a certain operating system feature and
+          * returns the result of that OS feature check as content (value) of
+          * this dynamic variable. Since the respective OS feature might become
+          * available/unavailable after OS updates, software migration, etc. the
+          * OS feature check should at least be performed once each time the
+          * application is launched. And since the OS feature check might take a
+          * certain amount of execution time, it might make sense to only
+          * perform the check if the respective variable name is actually
+          * referenced at all in the script to be loaded. Note that the dynamic
+          * variable will still be evaluated again though if the script is
+          * loaded again. So it is up to you to probably cache the result in the
+          * implementation of your dynamic variable.
+          *
+          * On doubt, please rather consider to use a constant built-in script
+          * variable instead of implementing a "constant" dynamic variable, due
+          * to the runtime overhead a dynamic variable may cause.
+          *
+          * @see isAssignable()
+          */
+         bool isConstExpr() const OVERRIDE { return false; }
+         /**
+          * In case this dynamic variable is assignable, the new value (content)
+          * to be assigned to this dynamic variable.
+          *
+          * By default this method does nothing. Override and implement this
+          * method in your subclass in case your dynamic variable allows to
+          * assign a new value by script.
+          *
+          * @param expr - new value to be assigned to this variable
+          */
+         void assignExpr(VMExpr* expr) OVERRIDE {}
+     };
+     /** @brief Dynamically executed variable (of integer data type).
+      *
+      * This is the base class for all built-in integer script variables whose
+      * variable content needs to be provided dynamically by executable native
+      * code on each script variable access.
+      */
+     class VMDynIntVar : virtual public VMDynVar, virtual public VMIntExpr {
+     public:
+     };
+     /** @brief Dynamically executed variable (of string data type).
+      *
+      * This is the base class for all built-in string script variables whose
+      * variable content needs to be provided dynamically by executable native
+      * code on each script variable access.
+      */
+     class VMDynStringVar : virtual public VMDynVar, virtual public VMStringExpr {
+     public:
+     };
      /** @brief Provider for built-in script functions and variables.
       *
       * Abstract base class defining the high-level interface for all classes
-Line 587 
 namespace LinuxSampler {
+Line 764 
 namespace LinuxSampler {
           * variables, which never change their value at runtime.
           */
          virtual std::map<String,int> builtInConstIntVariables() = 0;
+         /**
+          * Returns a variable name indexed map of all built-in dynamic variables,
+          * which are not simply data stores, rather each one of them executes
+          * natively to provide or alter the respective script variable data.
+          */
+         virtual std::map<String,VMDynVar*> builtInDynamicVariables() = 0;
      };
      /** @brief Execution state of a virtual machine.
-Line 664 
 namespace LinuxSampler {
+Line 848 
 namespace LinuxSampler {
       * issue (either a parser error or parser warning), a human readable
       * explanation text of the error or warning and the location of the
       * encountered parser issue within the script.
+      *
+      * @see VMSourceToken for processing syntax highlighting instead.
       */
      struct ParserIssue {
          String txt; ///< Human readable explanation text of the parser issue.
-Line 782 
 namespace LinuxSampler {
+Line 968 
 namespace LinuxSampler {
       * This class is not actually used by the sampler itself. It is rather
       * provided for external script editor applications. Primary purpose of
       * this class is syntax highlighting for external script editors.
+      *
+      * @see ParserIssue for processing compile errors and warnings instead.
       */
      class VMSourceToken {
      public:
-Line 794 
 namespace LinuxSampler {
+Line 982 
 namespace LinuxSampler {
          String text() const;
          // position of token in script
-         int firstLine() const; ///< First line this source token is located at in script source code (indexed with 0 being the very first line).
+         int firstLine() const; ///< First line this source token is located at in script source code (indexed with 0 being the very first line). Most source code tokens are not spanning over multiple lines, the only current exception are comments, in the latter case you need to process text() to get the last line and last column for the comment.
-         int firstColumn() const; ///< Last line this source token is located at in script source code.
+         int firstColumn() const; ///< First column on the first line this source token is located at in script source code (indexed with 0 being the very first column). To get the length of this token use text().length().
          // base types
-         bool isEOF() const;
+         bool isEOF() const; ///< Returns true in case this source token represents the end of the source code file.
-         bool isNewLine() const;
+         bool isNewLine() const; ///< Returns true in case this source token represents a line feed character (i.e. "\n" on Unix systems).
-         bool isKeyword() const;
+         bool isKeyword() const; ///< Returns true in case this source token represents a language keyword (i.e. "while", "function", "declare", "on", etc.).
-         bool isVariableName() const;
+         bool isVariableName() const; ///< Returns true in case this source token represents a variable name (i.e. "$someIntVariable", "%someArrayVariable", "\@someStringVariable"). @see isIntegerVariable(), isStringVariable(), isArrayVariable() for the precise variable type.
-         bool isIdentifier() const;
+         bool isIdentifier() const; ///< Returns true in case this source token represents an identifier, which currently always means a function name.
-         bool isNumberLiteral() const;
+         bool isNumberLiteral() const; ///< Returns true in case this source token represents a number literal (i.e. 123).
-         bool isStringLiteral() const;
+         bool isStringLiteral() const; ///< Returns true in case this source token represents a string literal (i.e. "Some text").
-         bool isComment() const;
+         bool isComment() const; ///< Returns true in case this source token represents a source code comment.
-         bool isPreprocessor() const;
+         bool isPreprocessor() const; ///< Returns true in case this source token represents a preprocessor statement.
-         bool isOther() const;
+         bool isOther() const; ///< Returns true in case this source token represents anything else not covered by the token types mentioned above.
          // extended types
-         bool isIntegerVariable() const;
+         bool isIntegerVariable() const; ///< Returns true in case this source token represents an integer variable name (i.e. "$someIntVariable").
-         bool isStringVariable() const;
+         bool isStringVariable() const; ///< Returns true in case this source token represents an string variable name (i.e. "\@someStringVariable").
-         bool isArrayVariable() const;
+         bool isArrayVariable() const; ///< Returns true in case this source token represents an array variable name (i.e. "%someArryVariable").
-         bool isEventHandlerName() const;
+         bool isEventHandlerName() const; ///< Returns true in case this source token represents an event handler name (i.e. "note", "release", "controller").
          VMSourceToken& operator=(const VMSourceToken& other);

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