interp.rb

require './minruby'

def evaluate(tree, genv, lenv)
  case tree[0]
  when 'lit'
    tree[1]
  when '+'
    lenv['plus_count'] ||= 0
    lenv['plus_count'] += 1
    left = evaluate(tree[1], genv, lenv)
    right = evaluate(tree[2], genv, lenv)
    left + right
  when '-'
    left = evaluate(tree[1], genv, lenv)
    right = evaluate(tree[2], genv, lenv)
    left - right
  when '*'
    left = evaluate(tree[1], genv, lenv)
    right = evaluate(tree[2], genv, lenv)
    left * right
  when '/'
    left = evaluate(tree[1], genv, lenv)
    right = evaluate(tree[2], genv, lenv)
    left / right
  when '%'
    left = evaluate(tree[1], genv, lenv)
    right = evaluate(tree[2], genv, lenv)
    left % right
  when '**'
    left = evaluate(tree[1], genv, lenv)
    right = evaluate(tree[2], genv, lenv)
    left ** right
  when '=='
    left = evaluate(tree[1], genv, lenv)
    right = evaluate(tree[2], genv, lenv)
    left == right
  when '<'
    left = evaluate(tree[1], genv, lenv)
    right = evaluate(tree[2], genv, lenv)
    left < right
  when '>'
    left = evaluate(tree[1], genv, lenv)
    right = evaluate(tree[2], genv, lenv)
    left > right
  when '<='
    left = evaluate(tree[1], genv, lenv)
    right = evaluate(tree[2], genv, lenv)
    left <= right
  when '>='
    left = evaluate(tree[1], genv, lenv)
    right = evaluate(tree[2], genv, lenv)
    left >= right
  when 'func_def'
    genv[tree[1]] = ['user_defined', tree[2], tree[3]]
  when 'func_call'
    args = []
    i = 0
    while tree[i + 2]
      args[i] = evaluate(tree[i + 2], genv, lenv)
      i = i + 1
    end
    mhd = genv[tree[1]]
    if mhd[0] == "buildin"
      minruby_call(mhd[1], args)
    else
      new_lenv = {}
      params = mhd[1]
      i = 0
      while params[i]
        new_lenv[params[i]] = args[i]
        i = i + 1
      end
      evaluate(mhd[2], genv, new_lenv)
    end
  when 'stmts'
    i = 1
    last = nil
    while tree[i]
      last = evaluate(tree[i], genv, lenv)
      i = i + 1
    end
    last
  when 'var_assign'
    lenv[tree[1]] = evaluate(tree[2], genv, lenv)
  when 'var_ref'
    lenv[tree[1]]
  when "if"
    if evaluate(tree[1], genv, lenv)
      evaluate(tree[2], genv, lenv)
    else
      evaluate(tree[3], genv, lenv)
    end
  when "while"
    while evaluate(tree[1], genv, lenv)
      evaluate(tree[2], genv, lenv)
    end
  when "case"
    evaluate(tree[1], genv, lenv)
  else
    pp tree
  end
end

def max(tree)
  case tree[0]
  when 'lit'
    tree[1]
  else
    left = max(tree[1])
    right = max(tree[2])
    #[left, right].max
    left > right ? left : right
  end
end

str = minruby_load

tree = minruby_parse(str)
#pp tree
genv = { "p" => ["buildin", "p"],
  "pp" => ["buildin", "pp"] }
lenv = {}
answer = evaluate(tree, genv, lenv)
#p lenv
#p answer