SqlLexer = object of BaseLexer
  filename: string

SqlNode = ref SqlNodeObj

SqlNodeKind = enum
  nkNone, nkIdent, nkQuotedIdent, nkStringLit, nkBitStringLit, nkHexStringLit,
  nkIntegerLit, nkNumericLit, nkPrimaryKey, nkForeignKey, nkNotNull, nkNull,
  nkStmtList, nkDot, nkDotDot, nkPrefix, nkInfix, nkCall, nkPrGroup,
  nkColumnReference, nkReferences, nkDefault, nkCheck, nkConstraint, nkUnique,
  nkIdentity, nkColumnDef,  ## name, datatype, constraints
  nkInsert, nkUpdate, nkDelete, nkSelect, nkSelectDistinct, nkSelectColumns,
  nkSelectPair, nkAsgn, nkFrom, nkFromItemPair, nkGroup, nkLimit, nkHaving,
  nkOrder, nkJoin, nkDesc, nkUnion, nkIntersect, nkExcept, nkColumnList,
  nkValueList, nkWhere, nkCreateTable, nkCreateTableIfNotExists, nkCreateType,
  nkCreateTypeIfNotExists, nkCreateIndex, nkCreateIndexIfNotExists, nkEnumDef

SqlNodeObj = object
  case kind*: SqlNodeKind    ## kind of syntax tree
  of LiteralNodes:
      strVal*: string        ## AST leaf: the identifier, numeric literal
                             ## string literal, etc.
    
  else:
      sons*: seq[SqlNode]    ## the node's children
    
  

SqlParseError = object of ValueError

SqlParser = object of SqlLexer
  tok: Token

proc `$`(n: SqlNode): string {....raises: [Exception], tags: [RootEffect].}

proc `[]`(n: SqlNode; i: BackwardsIndex): SqlNode {....raises: [], tags: [].}

proc `[]`(n: SqlNode; i: int): SqlNode {....raises: [], tags: [].}

proc add(father, n: SqlNode) {....raises: [], tags: [].}

proc len(n: SqlNode): int {....raises: [], tags: [].}

proc newNode(k: SqlNodeKind): SqlNode {....raises: [], tags: [].}

proc newNode(k: SqlNodeKind; s: string): SqlNode {....raises: [], tags: [].}

proc newNode(k: SqlNodeKind; sons: seq[SqlNode]): SqlNode {....raises: [], tags: [].}

proc parseSql(input: Stream; filename: string): SqlNode {....raises: [IOError,
    OSError, IOError, OSError, ValueError, SqlParseError, Exception],
    tags: [ReadIOEffect, RootEffect, WriteIOEffect].}

proc parseSql(input: string; filename = ""): SqlNode {.
    ...raises: [IOError, OSError, ValueError, SqlParseError, Exception],
    tags: [ReadIOEffect, RootEffect, WriteIOEffect].}

proc renderSql(n: SqlNode; upperCase = false): string {....raises: [Exception],
    tags: [RootEffect].}

proc treeRepr(s: SqlNode): string {....raises: [], tags: [].}