# 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, Is, Return, 
    Coroutine, Generator, Import, 
    IsNot, Raise, Assert, Await, 
    Foreach, Yield, Of, Defer, 
    Try, Except, Finally, Type, 
    Operator, Case, Enum, From,
    Emit, As

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

    # Brackets, parentheses, 
    # operators and others

    LeftParen, RightParen, # ()
    LeftBrace, RightBrace, # {}
    LeftBracket, RightBracket, # []
    Dot, Semicolon, Colon, Comma, # . ; : ,
    Plus, Minus, Slash, Star, # + - / *
    Percentage, DoubleStar,   # % **
    Caret, Pipe, Ampersand, Tilde, # ^ | & ~
    Equal, GreaterThan, LessThan, # = > <
    LessOrEqual, GreaterOrEqual, # >= <=
    NotEqual, RightShift, LeftShift, # != >> <<
    LogicalAnd, LogicalOr, LogicalNot, # and or not
    InplaceAdd, InplaceSub, InplaceDiv, # += -= /=
    InplaceMod, InplaceMul, InplaceXor, # %= *= ^=
    InplaceAnd, InplaceOr, FloorDiv, # &= |= //
    DoubleEqual, InplaceFloorDiv, InplacePow, # == //= **=
    InplaceRightShift, InplaceLeftShift,   # >>= <<=

    # Miscellaneous

    EndOfFile,       # Marks the end of the token stream
    NoMatch,         # Used internally by the symbol table
    Comment,         # Useful for documentation comments, pragmas, etc.
    # 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 `$`*(self: Token): string =
  if self != nil:
    result = &"Token(kind={self.kind}, lexeme='{$(self.lexeme)}', line={self.line}, pos=({self.pos.start}, {self.pos.stop}))"
  else:
    result = "nil"