export as_prec;
export unop_prec;
export token_to_binop;

import token::*;
import token::token;
import ast::*;

/// Unary operators have higher precedence than binary
const unop_prec: uint = 100u;

/**
 * Precedence of the `as` operator, which is a binary operator
 * but is not represented in the precedence table.
 */
const as_prec: uint = 11u;

/**
 * Maps a token to a record specifying the corresponding binary
 * operator and its precedence
 */
fn token_to_binop(tok: token) -> Option<ast::binop> {
  match tok {
      BINOP(STAR)    => Some(mul),
      BINOP(SLASH)   => Some(div),
      BINOP(PERCENT) => Some(rem),
      // 'as' sits between here with 11
      BINOP(PLUS)    => Some(add),
      BINOP(MINUS)   => Some(subtract),
      BINOP(SHL)     => Some(shl),
      BINOP(SHR)     => Some(shr),
      BINOP(AND)     => Some(bitand),
      BINOP(CARET)   => Some(bitxor),
      BINOP(OR)      => Some(bitor),
      LT             => Some(lt),
      LE             => Some(le),
      GE             => Some(ge),
      GT             => Some(gt),
      EQEQ           => Some(eq),
      NE             => Some(ne),
      ANDAND         => Some(and),
      OROR           => Some(or),
      _              => None
  }
}