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Annotation of parser3/src/types/pa_junction.h, revision 1.1.2.2

1.1.2.1   paf         1: /** @file
                      2:        Parser: Junction class decl.
                      3: 
                      4:        Copyright (c) 2001-2003 ArtLebedev Group (http://www.artlebedev.com)
                      5:        Author: Alexandr Petrosian <paf@design.ru> (http://paf.design.ru)
                      6: */
                      7: 
                      8: #ifndef PA_JUNCTION_H
                      9: #define PA_JUNCTION_H
                     10: 
1.1.2.2 ! paf        11: static const char* IDENT_JUNCTION_H="$Date: 2003/02/04 09:06:55 $";
1.1.2.1   paf        12: 
                     13: #include "pa_pool.h"
                     14: #include "pa_string.h"
                     15: #include "pa_array.h"
                     16: #include "pa_exception.h"
                     17: #include "pa_operation.h"
                     18: #include "pa_value.h"
                     19: 
                     20: /** \b junction is some code joined with context of it's evaluation.
                     21: 
                     22:        there are code-junctions and method-junctions
                     23:        - code-junctions are used when some parameter passed in cury brackets
                     24:        - method-junctions used in ^method[] calls or $method references
                     25: 
                     26:        Junctions register themselves in method_frame [if any] for consequent invalidation.
                     27:        This prevents evaluation of junctions in outdated context
                     28: 
                     29:        To stop situations like this:
                     30: @code
                     31:        @main[]
                     32:        ^method1[]
                     33:        ^method2[]
                     34: 
                     35:        @method1[]
                     36:        $junction{
                     37:                some code
                     38:        }
                     39: 
                     40:        @method2[]
                     41:        ^junction[]
                     42: @endcode
                     43: 
                     44:        On wcontext[most dynamic context of all] scope exit (WContext::~WContext()) got cleaned - 
                     45:        Junction::wcontext becomes WContext.fparent (if any), 
                     46:        or Junction::method_frame becomes 0 (if no parent), which later in Request::process triggers exception
                     47: 
                     48:        parent changing helps ^switch implementation to remain simple
                     49: */
                     50: class Junction: public PA_Object {
                     51: public:
                     52: 
                     53:        Junction(
                     54:                ValuePtr aself,
                     55:                const Method* amethod,
                     56:                VMethodFrame* amethod_frame,
                     57:                Value* arcontext,
                     58:                WContext* awcontext,
                     59:                ArrayOperationPtr acode);
                     60: 
                     61:        void reattach(WContext *new_wcontext);
                     62: 
                     63:        /// always present
                     64:        ValuePtr self;
                     65:        //@{
                     66:        /// @name either these // so called 'method-junction'
                     67:        const Method* method;
                     68:        //@}
                     69:        //@{
                     70:        /// @name or these are present // so called 'code-junction'
                     71:        VMethodFrame* method_frame;
                     72:        Value* rcontext;
                     73:        WContext* wcontext;
                     74:        ArrayOperationPtr code;
                     75:        //@}
                     76: };
                     77: 
                     78: #endif