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import { getLine } from "./utils_line"

// A Pos instance represents a position within the text.
export function Pos (line, ch) {
  if (!(this instanceof Pos)) return new Pos(line, ch)
  this.line = line; this.ch = ch
}

// Compare two positions, return 0 if they are the same, a negative
// number when a is less, and a positive number otherwise.
export function cmp(a, b) { return a.line - b.line || a.ch - b.ch }

export function copyPos(x) {return Pos(x.line, x.ch)}
export function maxPos(a, b) { return cmp(a, b) < 0 ? b : a }
export function minPos(a, b) { return cmp(a, b) < 0 ? a : b }

// Most of the external API clips given positions to make sure they
// actually exist within the document.
export function clipLine(doc, n) {return Math.max(doc.first, Math.min(n, doc.first + doc.size - 1))}
export function clipPos(doc, pos) {
  if (pos.line < doc.first) return Pos(doc.first, 0)
  let last = doc.first + doc.size - 1
  if (pos.line > last) return Pos(last, getLine(doc, last).text.length)
  return clipToLen(pos, getLine(doc, pos.line).text.length)
}
function clipToLen(pos, linelen) {
  let ch = pos.ch
  if (ch == null || ch > linelen) return Pos(pos.line, linelen)
  else if (ch < 0) return Pos(pos.line, 0)
  else return pos
}
export function clipPosArray(doc, array) {
  let out = []
  for (let i = 0; i < array.length; i++) out[i] = clipPos(doc, array[i])
  return out
}