AnyOperator.hs

module PostgresqlSyntax.Ast.AnyOperator where

import qualified HeadedMegaparsec as Parser
import PostgresqlSyntax.Algebra
import PostgresqlSyntax.Ast.AllOp
import PostgresqlSyntax.Ast.Ident
import qualified PostgresqlSyntax.Helpers.Gens as Gens
import qualified PostgresqlSyntax.Helpers.Parsers as Parsers
import qualified PostgresqlSyntax.KeywordSet as KeywordSet
import PostgresqlSyntax.Prelude
import qualified Test.QuickCheck as Qc

-- |
-- ==== References
-- @
-- any_operator:
--   | all_Op
--   | ColId '.' any_operator
-- @
--
-- 'PostgresqlSyntax.Ast.ColId' is a bare alias to 'Ident', but its /parser/
-- (kept in "PostgresqlSyntax.Parsing" since @ColId@ itself isn't extracted
-- in this batch) is more permissive than plain 'Ident'. Since this module
-- sits below "PostgresqlSyntax.Parsing" (no import cycle allowed), that
-- ColId-flavored element parser is duplicated here (mirroring @colId@'s
-- definition), same as 'PostgresqlSyntax.Ast.NameList'.
data AnyOperator
  = AllOpAnyOperator AllOp
  | QualifiedAnyOperator Ident AnyOperator
  deriving (Show, Generic, Eq, Ord, Data)

instance IsAst AnyOperator where
  toTextBuilder settings = \case
    AllOpAnyOperator a -> toTextBuilder settings a
    QualifiedAnyOperator a b -> toTextBuilder settings a <> "." <> toTextBuilder settings b
  parser settings =
    asum
      [ AllOpAnyOperator <$> parser settings,
        QualifiedAnyOperator <$> colIdLikeName <*> (Parsers.space *> Parsers.char '.' *> Parsers.space *> parser settings)
      ]
    where
      colIdLikeName =
        Parser.label "identifier" $
          parser settings
            <|> Parsers.keywordNameFromSet UnquotedIdent (KeywordSet.unreservedKeyword <> KeywordSet.colNameKeyword)

instance Qc.Arbitrary AnyOperator where
  shrink = Qc.genericShrink
  arbitrary = Qc.sized $ \n ->
    if n <= 1
      then AllOpAnyOperator <$> Qc.arbitrary
      else
        Qc.oneof
          [ AllOpAnyOperator <$> Qc.arbitrary,
            QualifiedAnyOperator <$> Qc.arbitrary <*> Gens.downscale Qc.arbitrary
          ]