# 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, 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, 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"