50 lines
2.2 KiB
Markdown
50 lines
2.2 KiB
Markdown
---
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layout: soml
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title: Parfait, soml's runtime
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---
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#### Overview
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Soml, like ruby, has open classes. This means that a class can be added to by loading another file
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with the same class definition that adds fields or methods. The effect of this is that in designing
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the runtime, we can concentrate on a minimal function set.
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This means all the functionality the compiler need to get the job done, mostly class and type
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structure related functionality with it's support.
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### Value and Object
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In soml object is not the root of the class hierarchy, but Value is. Integer, Float and Object are
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derived from Value. So an integer is *not* an object, but still has a class and methods, just no
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instance variables.
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### Layout and Class
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Each object has a layout that describes the instance variables and types of the object. It also
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reference the class of the object. Layout objects are constant, may not be changed over their
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lifetime. When a field is added to a class, a new layout is created.
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A Class describes a set of objects that respond to the same methods (methods are store in the class).
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A Layout describes a set of objects that have the same instance variables.
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### Method, Message and Frame
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The Method class describes a declared method. It carries a name, argument names and types and
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several description of the code. The parsed ast is kept for later inlining, the register model
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instruction stream for optimisation and further processing and finally the cpu specific binary
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represents the executable code.
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When Methods are invoked, A message object (instance of Message class) is populated. Message objects
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are created at compile time and form a linked list. The data in the Message holds the receiver,
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return addresses, arguments and a frame. Frames are also created at compile time and just reused
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at runtime.
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### Space and support
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The single instance of Space hold a list of all Classes, which in turn hold the methods.
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Also the space holds messages will hold memory management objects like pages.
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Words represent short immutable text and other word processing (buffers, text) is still tbd.
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Lists are number indexed, starting at one, and dictionaries are mappings from words to objects.
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