Part of the output of CompilerLalrParserSpec

Hold the results of cpmuting the LALR(1) closure of an LR(0) kernel

 Indexes into the memoizing table for the Goto computations
 Embed in a single integer, since these are faster
 keys for the dictionary hash tables

 Logically:

   type GotoItemIndex = GotoItemIdx of KernelIdx * SymbolIndex

Represent (ProductionIndex,ProdictionDotIndex) as one integer

LR(0) kernels

Indexes of LR(0) kernels in the KernelTable

 Indexes in the LookaheadTable, SpontaneousTable, PropagateTable
 Embed in a single integer, since these are faster
 keys for the dictionary hash tables

 Logically:

   type KernelItemIndex = KernelItemIdx of KernelIdx * Item0

A mutable table giving an index to each LR(0) kernel. Kernels are referred to only by index.

A mutable table maping kernels to sets of lookahead tokens

Allocate indexes for each non-terminal

Allocate indexes for each production

A mutable table giving a Set for each kernel. The kernels represent the "propagate" items for the kernel. TODO: document this more w.r.t. the Dragon book.

A mutable table giving a lookahead set Set for each kernel. The terminals represent the "spontaneous" items for the kernel. TODO: document this more w.r.t. the Dragon book.

 Representation of Symbols.
 Ideally would be declared as
    type SymbolIndex = PTerminal of TerminalIndex | PNonTerminal of NonTerminalIndex
 but for performance reasons we embed as a simple integer (saves ~10%)

 We use an active pattern to reverse the embedding.

Indexes in the TerminalTable and NonTerminalTable

Allocate indexes for each terminal