class Steep::AST::Buffer

def initialize(name:, content:)
  @name = name
  @content = content
  @lines = content.split(/\n/, -1)
  @ranges = []
  offset = 0
  lines.each.with_index do |line, index|
    if index == lines.size - 1
      ranges << (offset..offset)
    else
      size = line.size
      range = offset..(offset+size)
      ranges << range
      offset += size+1
    end
  end
end

def loc_to_pos(loc)
  line, column = loc
  ranges[line - 1].begin + column
end

def pos_to_loc(pos)
  index = ranges.bsearch_index do |range|
    pos <= range.end
  end
  if index
    [index + 1, pos - ranges[index].begin]
  else
    [1, pos]
  end
end

def source(range)
  content[range]
end