# Copyright 2022 Mattia Giambirtone & All Contributors
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
#    http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.

import strformat


type

  TokenType* {.pure.} = enum
    ## Token types enumeration

    # Booleans
    True, False,

    # Other singleton types
    Infinity, NotANumber, Nil

    # Control flow statements
    If, Else,

    # Looping statements
    While, For,

    # Keywords
    Function, Break, Continue,
    Var, Let, Const, Return,
    Coroutine, Generator, Import,
    Raise, Assert, Await, Foreach,
    Yield, Defer, Try, Except,
    Finally, Type, Operator, Case,
    Enum, From, Ptr, Ref

    # Literal types
    Integer, Float, String, Identifier,
    Binary, Octal, Hex, Char

    # Brackets, parentheses,
    # operators and others

    LeftParen, RightParen, # ()
    LeftBrace, RightBrace, # {}
    LeftBracket, RightBracket, # []
    Dot, Semicolon, Comma, # . ; ,

      # Miscellaneous

    EndOfFile, # Marks the end of the token stream
    NoMatch, # Used internally by the symbol table
    Comment, # Useful for documentation comments, pragmas, etc.
    Symbol, # A generic symbol
              # These are not used at the moment but may be
              # employed to enforce indentation or other neat
              # stuff I haven't thought about yet
    Whitespace,
    Tab,


  Token* = ref object
    ## A token object
    kind*: TokenType              # Type of the token
    lexeme*: string               # The lexeme associated to the token
    line*: int                    # The line where the token appears
    pos*: tuple[start, stop: int] # The absolute position in the source file
                                  # (0-indexed and inclusive at the beginning)



proc `$`*(self: Token): string =
  ## Strinfifies
  if self != nil:
    result = &"Token(kind={self.kind}, lexeme='{$(self.lexeme)}', line={self.line}, pos=({self.pos.start}, {self.pos.stop}))"
  else:
    result = "nil"


proc `==`*(self, other: Token): bool =
  ## Returns self == other
  return self.kind == other.kind and self.lexeme == other.lexeme