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Create the 'Tables' data type
This data type encapsulates the result of processing the Grammar. In addition to ActionTable and GotoTable, it also includes intermediate results such as Lr0Items, which are needed for debug printing and info table generation. The 'find_redundancies' function has been moved from Main.lhs to Tabular.lhs almost verbatim (use git show --color-moved=blocks to confirm).
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‎happy.cabal

+2-1
Original file line numberDiff line numberDiff line change
@@ -164,7 +164,7 @@ executable happy
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-- mtl-2.2.1 added Control.Monad.Except
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default-language: Haskell98
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default-extensions: CPP, MagicHash, FlexibleContexts
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default-extensions: CPP, MagicHash, FlexibleContexts, NamedFieldPuns
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ghc-options: -Wall
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other-modules:
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Paths_happy
@@ -181,6 +181,7 @@ executable happy
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ProduceCode
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ProduceGLRCode
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NameSet
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Tabular
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Target
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AttrGrammar
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ParamRules

‎src/LALR.lhs

+1-1
Original file line numberDiff line numberDiff line change
@@ -8,7 +8,7 @@ Generation of LALR parsing tables.
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> module LALR
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> (genActionTable, genGotoTable, genLR0items, precalcClosure0,
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> propLookaheads, calcLookaheads, mergeLookaheadInfo, countConflicts,
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> Lr0Item(..), Lr1Item)
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> Lr0Item(..), Lr1Item, ItemSetWithGotos)
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> where
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> import GenUtils

‎src/Main.lhs

+14-61
Original file line numberDiff line numberDiff line change
@@ -17,8 +17,7 @@ Path settings auto-generated by Cabal:
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> import PrettyGrammar
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> import Parser
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> import First
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> import LALR
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> import Tabular
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> import ProduceCode (produceParser)
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> import ProduceGLRCode
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> import Info (genInfoFile)
@@ -29,8 +28,7 @@ Path settings auto-generated by Cabal:
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> import System.Exit (exitWith, ExitCode(..))
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> import Data.Char
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> import System.IO
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> import Data.Array( assocs, elems, (!) )
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> import Data.List( nub, isSuffixOf )
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> import Data.List( isSuffixOf )
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> import Data.Version ( showVersion )
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> main :: IO ()
@@ -84,30 +82,28 @@ Mangle the syntax into something useful.
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> optPrint cli DumpMangle $ putStr $ show g
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> let first = {-# SCC "First" #-} (mkFirst g)
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> closures = {-# SCC "Closures" #-} (precalcClosure0 g)
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> sets = {-# SCC "LR0_Sets" #-} (genLR0items g closures)
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> _lainfo@(spont,prop) = {-# SCC "Prop" #-} (propLookaheads g sets first)
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> la = {-# SCC "Calc" #-} (calcLookaheads (length sets) spont prop)
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> items2 = {-# SCC "Merge" #-} (mergeLookaheadInfo la sets)
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> goto = {-# SCC "Goto" #-} (genGotoTable g sets)
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> action = {-# SCC "Action" #-} (genActionTable g first items2)
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> (conflictArray,(sr,rr)) = {-# SCC "Conflict" #-} (countConflicts action)
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> let select_reductions | OptGLR `elem` cli = select_all_reductions
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> | otherwise = select_first_reduction
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> let tables = genTables select_reductions g
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> sets = lr0items tables
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> lainfo = (la_prop tables, la_spont tables)
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> la = lookaheads tables
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> goto = gotoTable tables
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> action = actionTable tables
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> (conflictArray,(sr,rr)) = conflicts tables
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Debug output
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> optPrint cli DumpLR0 $ putStr $ show sets
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> optPrint cli DumpAction $ putStr $ show action
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> optPrint cli DumpGoto $ putStr $ show goto
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> optPrint cli DumpLA $ putStr $ show _lainfo
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> optPrint cli DumpLA $ putStr $ show lainfo
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> optPrint cli DumpLA $ putStr $ show la
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Report any unused rules and terminals
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> let reduction_filter | OptGLR `elem` cli = any_reduction
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> | otherwise = first_reduction
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> (unused_rules, unused_terminals)
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> = find_redundancies reduction_filter g action
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> let (unused_rules, unused_terminals) = redundancies tables
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> when (not (null unused_rules))
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> (hPutStrLn stderr ("unused rules: " ++ show (length unused_rules)))
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> when (not (null unused_terminals))
@@ -298,49 +294,6 @@ Successfully Finished.
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> constArgs :: [String]
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> constArgs = []
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-----------------------------------------------------------------------------
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Find unused rules and tokens
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> find_redundancies
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> :: (LRAction -> [Int]) -> Grammar -> ActionTable -> ([Int], [String])
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> find_redundancies extract_reductions g action_table =
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> (unused_rules, map (env !) unused_terminals)
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> where
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> Grammar { terminals = terms,
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> token_names = env,
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> eof_term = eof,
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> starts = starts',
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> productions = productions'
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> } = g
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> actions = concat (map assocs (elems action_table))
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> start_rules = [ 0 .. (length starts' - 1) ]
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> used_rules = start_rules ++
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> nub [ r | (_,a) <- actions, r <- extract_reductions a ]
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> used_tokens = errorTok : eof :
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> nub [ t | (t,a) <- actions, is_shift a ]
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> n_prods = length productions'
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> unused_terminals = filter (`notElem` used_tokens) terms
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> unused_rules = filter (`notElem` used_rules ) [0..n_prods-1]
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> is_shift :: LRAction -> Bool
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> is_shift (LR'Shift _ _) = True
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> is_shift (LR'Multiple _ LR'Shift{}) = True
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> is_shift _ = False
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---
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selects what counts as a reduction when calculating used/unused
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> any_reduction :: LRAction -> [Int]
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> any_reduction (LR'Reduce r _) = [r]
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> any_reduction (LR'Multiple as a) = concatMap any_reduction (a : as)
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> any_reduction _ = []
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> first_reduction :: LRAction -> [Int]
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> first_reduction (LR'Reduce r _) = [r]
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> first_reduction (LR'Multiple _ a) = first_reduction a -- eg R/R conflict
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> first_reduction _ = []
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------------------------------------------------------------------------------
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346299
> possDelit :: String -> String -> IO (String,String)

‎src/Tabular.lhs

+93
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,93 @@
1+
> module Tabular (
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> Tables(..),
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> genTables,
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> SelectReductions,
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> select_all_reductions,
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> select_first_reduction
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> ) where
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9+
> import NameSet (NameSet)
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> import First
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> import Grammar
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> import LALR
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> import Data.Array( Array, assocs, elems, (!) )
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> import Data.List ( nub )
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17+
> data Tables =
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> Tables {
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> lr0items :: [ItemSetWithGotos],
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> la_spont :: [(Int, Lr0Item, NameSet)],
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> la_prop :: Array Int [(Lr0Item, Int, Lr0Item)],
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> lookaheads :: Array Int [(Lr0Item, NameSet)],
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> lr1items :: [ ([Lr1Item], [(Name,Int)]) ],
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> gotoTable :: GotoTable,
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> actionTable :: ActionTable,
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> conflicts :: (Array Int (Int,Int), (Int,Int)),
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> redundancies :: ([Int], [String])
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> }
29+
30+
> genTables ::
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> SelectReductions -> -- for computing used/unused
32+
> Grammar ->
33+
> Tables
34+
> genTables select_reductions g =
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> let first = {-# SCC "First" #-} (mkFirst g)
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> closures = {-# SCC "Closures" #-} (precalcClosure0 g)
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> lr0items = {-# SCC "LR0_Sets" #-} (genLR0items g closures)
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> (la_spont, la_prop)
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> = {-# SCC "Prop" #-} (propLookaheads g lr0items first)
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> lookaheads = {-# SCC "Calc" #-} (calcLookaheads (length lr0items) la_spont la_prop)
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> lr1items = {-# SCC "Merge" #-} (mergeLookaheadInfo lookaheads lr0items)
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> gotoTable = {-# SCC "Goto" #-} (genGotoTable g lr0items)
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> actionTable = {-# SCC "Action" #-} (genActionTable g first lr1items)
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> conflicts = {-# SCC "Conflict" #-} (countConflicts actionTable)
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> redundancies = find_redundancies select_reductions g actionTable
46+
> in Tables { lr0items, la_spont, la_prop, lookaheads, lr1items,
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> gotoTable, actionTable, conflicts, redundancies }
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49+
-----------------------------------------------------------------------------
50+
Find unused rules and tokens
51+
52+
> find_redundancies
53+
> :: SelectReductions -> Grammar -> ActionTable -> ([Int], [String])
54+
> find_redundancies extract_reductions g action_table =
55+
> (unused_rules, map (env !) unused_terminals)
56+
> where
57+
> Grammar { terminals = terms,
58+
> token_names = env,
59+
> eof_term = eof,
60+
> starts = starts',
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> productions = productions'
62+
> } = g
63+
> actions = concat (map assocs (elems action_table))
64+
> start_rules = [ 0 .. (length starts' - 1) ]
65+
> used_rules = start_rules ++
66+
> nub [ r | (_,a) <- actions, r <- extract_reductions a ]
67+
> used_tokens = errorTok : eof :
68+
> nub [ t | (t,a) <- actions, is_shift a ]
69+
> n_prods = length productions'
70+
> unused_terminals = filter (`notElem` used_tokens) terms
71+
> unused_rules = filter (`notElem` used_rules ) [0..n_prods-1]
72+
73+
> is_shift :: LRAction -> Bool
74+
> is_shift (LR'Shift _ _) = True
75+
> is_shift (LR'Multiple _ LR'Shift{}) = True
76+
> is_shift _ = False
77+
78+
---
79+
selects what counts as a reduction when calculating used/unused
80+
81+
> type SelectReductions = LRAction -> [Int]
82+
83+
> select_all_reductions :: SelectReductions
84+
> select_all_reductions = go
85+
> where go (LR'Reduce r _) = [r]
86+
> go (LR'Multiple as a) = concatMap go (a : as)
87+
> go _ = []
88+
89+
> select_first_reduction :: SelectReductions
90+
> select_first_reduction = go
91+
> where go (LR'Reduce r _) = [r]
92+
> go (LR'Multiple _ a) = go a -- eg R/R conflict
93+
> go _ = []

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