substring-of-rope.js

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gczeal(0);

const hasStringRepresentation = typeof stringRepresentation !== "undefined";

function assertSameAddress(s1, s2) {

  if (hasStringRepresentation) {

    var s1Repr = stringRepresentation(s1);

    var s2Repr = stringRepresentation(s2);

    var s1Addr = JSON.parse(s1Repr).address;

    var s2Addr = JSON.parse(s2Repr).address;

    assertEq(typeof s1Addr, "string");

    assertEq(s1Addr, s2Addr);

// rope.substring(0) should not allocate a new string or flatten the rope.

function testSameSubstring() {

  var rope = newRope("abcdefghijklmnop", "0123456789");

  for (var i = 0; i < 5; i++) {

    var sub = rope.substring(0);

    assertEq(isRope(sub), true);

    assertSameAddress(rope, sub);

testSameSubstring();

// If the substring is exactly the left or right child, we should return it

// without flattening the rope.

function testLeftRightSubstring() {

  var left = "abcdefghijklmnopqrstuvwxyz";

  var right = "012345678901234567890123456789";

  var rope = newRope(left, right);

  for (var i = 0; i < 10; i++) {

    assertSameAddress(rope.substring(0, left.length), left);

    assertSameAddress(rope.substring(left.length), right);

    assertEq(isRope(rope), true); // Still a rope.

testLeftRightSubstring();

function testSubstringSpansBoth() {

  var left = "abcdefghijklmnopqrstuvwxyz";

  var right = "012345678901234567890123456789";

  var rope = newRope(left, right);

  // If the substring spans both left and right children but fits in an inline

  // string, don't flatten the rope.

  for (var i = 0; i < 10; i++) {

    var substrInline = rope.substring(left.length - 5, left.length + 5);

    if (hasStringRepresentation) {

      assertEq(stringRepresentation(substrInline).includes("InlineString"), true);

    assertEq(substrInline, "vwxyz01234");

    assertEq(isRope(rope), true); // Still a rope.

  // If the substring doesn't fit in an inline string, we flatten the rope and

  // return a dependent string.

  var substrLong = rope.substring(0, rope.length - 1);

  assertEq(isRope(rope), false);

  assertEq(isRope(substrLong), false);

testSubstringSpansBoth();