semantic/src/TreeSitter.hs

{-# LANGUAGE DataKinds #-}
module TreeSitter
( treeSitterParser
, defaultTermAssignment
) where

import Prologue hiding (Constructor)
import Category
import Data.Record
import Language
import qualified Language.C as C
import qualified Language.Go as Go
import qualified Language.JavaScript as JS
import qualified Language.Ruby as Ruby
import Parser
import Range
import Source
import qualified Syntax
import Foreign
import Foreign.C.String (peekCString)
import Foreign.Marshal.Array (allocaArray)
import Data.Text.Foreign (withCStringLen)
import qualified Syntax as S
import Term
import Text.Parser.TreeSitter hiding (Language(..))
import qualified Text.Parser.TreeSitter as TS
import SourceSpan
import Info

-- | Returns a TreeSitter parser for the given language and TreeSitter grammar.
treeSitterParser :: Language -> Ptr TS.Language -> Parser (Syntax.Syntax Text) (Record '[Range, Category, SourceSpan])
treeSitterParser language grammar blob = do
  document <- ts_document_new
  ts_document_set_language document grammar
  withCStringLen (toText (source blob)) $ \ (source, len) -> do
    ts_document_set_input_string_with_length document source len
    ts_document_parse document
    term <- documentToTerm language document blob
    ts_document_free document
    pure term


-- | Return a parser for a tree sitter language & document.
documentToTerm :: Language -> Ptr Document -> Parser (Syntax.Syntax Text) (Record '[Range, Category, SourceSpan])
documentToTerm language document SourceBlob{..} = do
  root <- alloca (\ rootPtr -> do
    ts_document_root_node_p document rootPtr
    peek rootPtr)
  toTerm root source
  where toTerm :: Node -> Source -> IO (Term (Syntax.Syntax Text) (Record '[Range, Category, SourceSpan]))
        toTerm node source = do
          name <- peekCString (nodeType node)

          children <- getChildren (fromIntegral (nodeNamedChildCount node)) copyNamed
          let allChildren = getChildren (fromIntegral (nodeChildCount node)) copyAll

          assignTerm language source (range :. categoryForLanguageProductionName language (toS name) :. nodeSpan node :. Nil) children allChildren
          where getChildren count copy = do
                  nodes <- allocaArray count $ \ childNodesPtr -> do
                    _ <- with (nodeTSNode node) (\ nodePtr -> copy nodePtr childNodesPtr (fromIntegral count))
                    peekArray count childNodesPtr
                  children <- traverse childNodeToTerm nodes
                  return $! filter isNonEmpty children
                childNodeToTerm childNode = toTerm childNode (slice (offsetRange (nodeRange childNode) (negate (start range))) source)
                range = nodeRange node
        copyNamed = ts_node_copy_named_child_nodes document
        copyAll = ts_node_copy_child_nodes document


isNonEmpty :: HasField fields Category => SyntaxTerm Text fields -> Bool
isNonEmpty = (/= Empty) . category . extract

nodeRange :: Node -> Range
nodeRange Node{..} = Range (fromIntegral nodeStartByte) (fromIntegral nodeEndByte)

nodeSpan :: Node -> SourceSpan
nodeSpan Node{..} = nodeStartPoint `seq` nodeEndPoint `seq` SourceSpan (pointPos nodeStartPoint) (pointPos nodeEndPoint)
  where pointPos Point{..} = pointRow `seq` pointColumn `seq` SourcePos (1 + fromIntegral pointRow) (1 + fromIntegral pointColumn)

assignTerm :: Language -> Source -> Record '[Range, Category, SourceSpan] -> [ SyntaxTerm Text '[ Range, Category, SourceSpan ] ] -> IO [ SyntaxTerm Text '[ Range, Category, SourceSpan ] ] -> IO (SyntaxTerm Text '[ Range, Category, SourceSpan ])
assignTerm language source annotation children allChildren =
  cofree . (annotation :<) <$> case assignTermByLanguage language source (category annotation) children of
    Just a -> pure a
    _ -> defaultTermAssignment source (category annotation) children allChildren
  where assignTermByLanguage :: Language -> Source -> Category -> [ SyntaxTerm Text '[ Range, Category, SourceSpan ] ] -> Maybe (S.Syntax Text (SyntaxTerm Text '[ Range, Category, SourceSpan ]))
        assignTermByLanguage = \case
          JavaScript -> JS.termAssignment
          C -> C.termAssignment
          Language.Go -> Go.termAssignment
          Ruby -> Ruby.termAssignment
          _ -> \ _ _ _ -> Nothing

defaultTermAssignment :: Source -> Category -> [ SyntaxTerm Text '[Range, Category, SourceSpan] ] -> IO [ SyntaxTerm Text '[Range, Category, SourceSpan] ] -> IO (S.Syntax Text (SyntaxTerm Text '[Range, Category, SourceSpan]))
defaultTermAssignment source category children allChildren
  | category `elem` operatorCategories = S.Operator <$> allChildren
  | otherwise = pure $! case (category, children) of
    (ParseError, children) -> S.ParseError children

    (Comment, _) -> S.Comment (toText source)

    (Pair, [key, value]) -> S.Pair key value

    -- Control flow statements
    (If, condition : body) -> S.If condition body
    (Switch, _) -> uncurry S.Switch (Prologue.break ((== Case) . Info.category . extract) children)
    (Case, expr : body) -> S.Case expr body
    (While, expr : rest) -> S.While expr rest

    -- Statements
    (Return, _) -> S.Return children
    (Yield, _) -> S.Yield children
    (Throw, [expr]) -> S.Throw expr
    (Break, [label]) -> S.Break (Just label)
    (Break, []) -> S.Break Nothing
    (Continue, [label]) -> S.Continue (Just label)
    (Continue, []) -> S.Continue Nothing

    (_, []) -> S.Leaf (toText source)
    (_, children) -> S.Indexed children
  where operatorCategories =
          [ Operator
          , Binary
          , Unary
          , RangeExpression
          , ScopeOperator
          , BooleanOperator
          , MathOperator
          , RelationalOperator
          , BitwiseOperator
          ]


categoryForLanguageProductionName :: Language -> Text -> Category
categoryForLanguageProductionName = withDefaults . \case
  JavaScript -> JS.categoryForJavaScriptProductionName
  C -> C.categoryForCProductionName
  Ruby -> Ruby.categoryForRubyName
  Language.Go -> Go.categoryForGoName
  _ -> Other
  where withDefaults productionMap = \case
          "ERROR" -> ParseError
          s -> productionMap s