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天文台pc/tianwentai-ui/node_modules/d3-interpolate/src/string.js 1.72 KB
bc518174   王天杨   提交两个项目文件
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  import number from "./number.js";
  
  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) + "";
    };
  }
  
  export default function(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: number(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("");
          });
  }