phino-0.0.0.57: src/Rewriter.hs
{-# LANGUAGE DeriveAnyClass #-}
{-# LANGUAGE DerivingStrategies #-}
{-# LANGUAGE DuplicateRecordFields #-}
{-# LANGUAGE LambdaCase #-}
{-# LANGUAGE RecordWildCards #-}
{-# OPTIONS_GHC -Wno-name-shadowing #-}
-- SPDX-FileCopyrightText: Copyright (c) 2025 Objectionary.com
-- SPDX-License-Identifier: MIT
module Rewriter (rewrite, RewriteContext (..), Rewritten) where
import AST
import Builder
import Control.Exception (Exception, throwIO)
import Data.Char (toLower)
import Data.Functor ((<&>))
import Data.Maybe (fromMaybe)
import qualified Data.Set as Set
import Deps
import Locator (locatedExpression, withLocatedExpression)
import Logger (logDebug)
import Matcher (Subst)
import Must (Must (..), exceedsUpperBound, inRange)
import Printer (printExpression)
import Replacer (ReplaceContext (ReplaceCtx), ReplaceExpressionFunc, replaceExpression, replaceExpressionFast)
import Rule (RuleContext (RuleContext))
import qualified Rule as R
import Text.Printf (printf)
import qualified Yaml as Y
type RewriteState = ([Rewritten], Set.Set Expression)
type Rewritten = (Program, Maybe String)
type ToReplace = (Expression, Expression, Expression, [Subst])
data RewriteContext = RewriteContext
{ _locator :: Expression
, _maxDepth :: Int
, _maxCycles :: Int
, _depthSensitive :: Bool
, _buildTerm :: BuildTermFunc
, _must :: Must
, _saveStep :: SaveStepFunc
}
data RewriteException
= MustBeGoing Must Int
| MustStopBefore Must Int
| StoppedOnLimit String Int
| LoopingRewriting String String Int
deriving (Exception)
instance Show RewriteException where
show (MustBeGoing mst cnt) =
printf
"With option --must=%s it's expected rewriting cycles to be in range [%s], but rewriting stopped after %d cycles"
(show mst)
(show mst)
cnt
show (MustStopBefore mst cnt) =
printf
"With option --must=%s it's expected rewriting cycles to be in range [%s], but rewriting has already reached %d cycles and is still going"
(show mst)
(show mst)
cnt
show (StoppedOnLimit flg lim) =
printf
"With option --depth-sensitive it's expected rewriting iterations amount does not reach the limit: --%s=%d"
flg
lim
show (LoopingRewriting expr rul stp) =
printf
"On rewriting step '%d' of rule '%s' we got the same expression as we got at one of the previous step, it seems rewriting is looping\nExpression: %s"
stp
rul
expr
-- Build pattern and result expression and replace patterns to results in given expression
buildAndReplace' :: ToReplace -> ReplaceExpressionFunc -> IO Expression
buildAndReplace' (expr, ptn, res, substs) func = do
ptns <- buildExpressionsThrows ptn substs
repls <- buildExpressionsThrows res substs
let ptns' = map fst ptns
repls' = map (\ex _ -> fst ex) repls
pure (func (expr, ptns', repls'))
-- If pattern and replacement are appropriate for fast replacing - does it.
-- Pattern and replacement expressions can be used in fast replacing only if
-- 1. they are both formations
-- 2. they start and end with the same meta bindings, e.g. [!B1, ..., !B2]
-- 3. the does not have meta bindings between first and last meta bindings
-- In such case we can just replace bindings one by one without building whole expression.
-- You can find more details in this ticket: https://github.com/objectionary/phino/issues/321
-- If we don't meet the conditions above - just do a regular replacing
tryBuildAndReplaceFast :: ToReplace -> ReplaceContext -> IO Expression
tryBuildAndReplaceFast state@(expr, ExFormation pbds, ExFormation rbds, substs) ctx =
let pbds' = init (tail pbds)
rbds' = init (tail rbds)
in if startsAndEndsWithMeta pbds
&& startsAndEndsWithMeta rbds
&& head pbds == head rbds
&& last pbds == last rbds
&& not (hasMetaBindings pbds')
&& not (hasMetaBindings rbds')
then do
logDebug "Applying fast replacing since 'pattern' and 'result' are suitable for this..."
buildAndReplace' (expr, ExFormation pbds', ExFormation rbds', substs) (replaceExpressionFast ctx)
else do
logDebug "Applying regular replacing..."
buildAndReplace' state replaceExpression
where
startsAndEndsWithMeta :: [Binding] -> Bool
startsAndEndsWithMeta bds =
length bds > 1
&& isMetaBinding (head bds)
&& isMetaBinding (last bds)
hasMetaBindings :: [Binding] -> Bool
isMetaBinding :: Binding -> Bool
isMetaBinding = \case
BiMeta _ -> True
_ -> False
hasMetaBindings = foldl (\acc bd -> acc || isMetaBinding bd) False
tryBuildAndReplaceFast state _ = buildAndReplace' state replaceExpression
-- The function returns tuple (X, Y) where
-- - X is sequence of programs;
-- - Y is Set of unique programs after each rule application. It allows to stop the rewriting if we're getting
-- into loop and get back to program which we've already got before
rewrite' :: RewriteState -> [Y.Rule] -> Int -> RewriteContext -> IO RewriteState
rewrite' state [] _ _ = pure state
rewrite' state (rule : rest) iteration ctx@RewriteContext{..} = do
state' <- _rewrite state 1
rewrite' state' rest iteration ctx
where
_rewrite :: RewriteState -> Int -> IO RewriteState
_rewrite (_rewrittens, _unique) _count =
let ruleName = fromMaybe "unknown" (Y.name rule)
ptn = Y.pattern rule
res = Y.result rule
(program, _) = head _rewrittens
in if _count - 1 == _maxDepth
then do
logDebug (printf "Max amount of rewriting cycles (%d) for rule '%s' has been reached, rewriting is stopped" _maxDepth ruleName)
if _depthSensitive
then throwIO (StoppedOnLimit "max-depth" _maxDepth)
else pure (_rewrittens, _unique)
else do
logDebug (printf "Starting rewriting cycle for rule '%s': %d out of %d" ruleName _count _maxDepth)
expression <- locatedExpression _locator program
matched <- R.matchExpressionWithRule expression rule (RuleContext _buildTerm)
if null matched
then do
logDebug (printf "Rule '%s' does not match, rewriting is stopped" ruleName)
pure (_rewrittens, _unique)
else do
logDebug (printf "Rule '%s' has been matched, applying..." ruleName)
expr <- tryBuildAndReplaceFast (expression, ptn, res, matched) (ReplaceCtx _maxDepth)
if expression == expr
then do
logDebug (printf "Applied '%s', no changes made" ruleName)
pure (_rewrittens, _unique)
else
if Set.member expr _unique
then throwIO (LoopingRewriting (printExpression expr) ruleName _count)
else do
logDebug
( printf
"Applied '%s' (%d nodes -> %d nodes)\n%s"
ruleName
(countNodes expression)
(countNodes expr)
(printExpression expr)
)
prog <- withLocatedExpression _locator expr program
_saveStep prog (((iteration - 1) * _maxDepth) + _count)
_rewrite (leadsTo prog, Set.insert expr _unique) (_count + 1)
where
leadsTo :: Program -> [Rewritten]
leadsTo _prog = case _rewrittens of
(program, _) : rest -> (_prog, Nothing) : (program, Just (map toLower (fromMaybe "unknown" (Y.name rule)))) : rest
[] -> [(_prog, Nothing)]
-- Rewrite program by provided locator from RewriteContext
rewrite :: Program -> [Y.Rule] -> RewriteContext -> IO [Rewritten]
rewrite prog rules ctx@RewriteContext{..} = _rewrite ([(prog, Nothing)], Set.empty) 0 <&> reverse
where
_rewrite :: RewriteState -> Int -> IO [Rewritten]
_rewrite state@(rewrittens, _) count
| not (inRange _must count) && count > 0 && exceedsUpperBound _must count = throwIO (MustStopBefore _must count)
| count == _maxCycles = do
logDebug (printf "Max amount of rewriting cycles for all rules (%d) has been reached, rewriting is stopped" _maxCycles)
if _depthSensitive
then throwIO (StoppedOnLimit "max-cycles" _maxCycles)
else pure rewrittens
| otherwise = do
logDebug (printf "Starting rewriting cycle for all rules: %d out of %d" count _maxCycles)
state'@(rewrittens', _) <- rewrite' state rules count ctx
let (program', _) = head rewrittens'
(program, _) = head rewrittens
if program' == program
then do
logDebug "Rewriting is stopped since it has no effect"
if not (inRange _must count)
then throwIO (MustBeGoing _must count)
else pure rewrittens'
else _rewrite state' (count + 1)