Avail
An AvailLabel is a pseudo-instruction in the Level One instruction set. It represents a label in the parse tree of a block. If a label declaration occurs at all in a block, it must be the first statement of the block.
No actual nybblecodes are generated for an AvailLabel. The only reason for a label pseudo-instruction to exist is to keep track of which blocks require labels.
Author
Mark van Gulik
Parameters
Constructors
Properties
true iff this instruction is a use of an outer variable.
Answer which line number to say that this instruction occurs on. Use the relevantTokens as an approximation, but subclasses might be able to be more precise. Answer -1 if this instruction doesn't seem to have a location in the source associated with it.
The tuple of tokens that contributed to producing this instruction.
Functions
The instructions of a block are being iterated over. Coordinate optimizations between instructions using localData and outerData, two lists manipulated by overrides of this method. Treat each instruction as though it is the last one in the block, and save enough information in the lists to be able to undo consequences of this assumption when a later instruction shows it to be unwarranted.
Write an entry to the encoded line number deltas for each L1 instruction generated. Most AvailInstructions write a single L1 instruction, so that implementation is here.
Write nybbles representing this instruction to the NybbleOutputStream.