source: node_modules/victory-vendor/lib-vendor/d3-interpolate/src/string.js

"use strict";

Object.defineProperty(exports, "__esModule", {
  value: true
});
exports.default = _default;
var _number = _interopRequireDefault(require("./number.js"));
function _interopRequireDefault(obj) { return obj && obj.__esModule ? obj : { default: obj }; }
var reA = /[-+]?(?:\d+\.?\d*|\.?\d+)(?:[eE][-+]?\d+)?/g,
  reB = new RegExp(reA.source, "g");
function zero(b) {
  return function () {
    return b;
  };
}
function one(b) {
  return function (t) {
    return b(t) + "";
  };
}
function _default(a, b) {
  var bi = reA.lastIndex = reB.lastIndex = 0,
    // scan index for next number in b
    am,
    // current match in a
    bm,
    // current match in b
    bs,
    // string preceding current number in b, if any
    i = -1,
    // index in s
    s = [],
    // string constants and placeholders
    q = []; // number interpolators

  // Coerce inputs to strings.
  a = a + "", b = b + "";

  // Interpolate pairs of numbers in a & b.
  while ((am = reA.exec(a)) && (bm = reB.exec(b))) {
    if ((bs = bm.index) > bi) {
      // a string precedes the next number in b
      bs = b.slice(bi, bs);
      if (s[i]) s[i] += bs; // coalesce with previous string
      else s[++i] = bs;
    }
    if ((am = am[0]) === (bm = bm[0])) {
      // numbers in a & b match
      if (s[i]) s[i] += bm; // coalesce with previous string
      else s[++i] = bm;
    } else {
      // interpolate non-matching numbers
      s[++i] = null;
      q.push({
        i: i,
        x: (0, _number.default)(am, bm)
      });
    }
    bi = reB.lastIndex;
  }

  // Add remains of b.
  if (bi < b.length) {
    bs = b.slice(bi);
    if (s[i]) s[i] += bs; // coalesce with previous string
    else s[++i] = bs;
  }

  // Special optimization for only a single match.
  // Otherwise, interpolate each of the numbers and rejoin the string.
  return s.length < 2 ? q[0] ? one(q[0].x) : zero(b) : (b = q.length, function (t) {
    for (var i = 0, o; i < b; ++i) s[(o = q[i]).i] = o.x(t);
    return s.join("");
  });
}