v8/test/mjsunit/string-slices.js

// Copyright 2011 the V8 project authors. All rights reserved.
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// modification, are permitted provided that the following conditions are
// met:
//
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// Flags: --expose-externalize-string --allow-natives-syntax

var s = 'abcdefghijklmn';
assertEquals(s, s.substr());
assertEquals(s, s.substr(0));
assertEquals(s, s.substr('0'));
assertEquals(s, s.substr(void 0));
assertEquals(s, s.substr(null));
assertEquals(s, s.substr(false));
assertEquals(s, s.substr(0.9));
assertEquals(s, s.substr({ valueOf: function() { return 0; } }));
assertEquals(s, s.substr({ toString: function() { return '0'; } }));

var s1 = s.substring(1);
assertEquals(s1, s.substr(1));
assertEquals(s1, s.substr('1'));
assertEquals(s1, s.substr(true));
assertEquals(s1, s.substr(1.1));
assertEquals(s1, s.substr({ valueOf: function() { return 1; } }));
assertEquals(s1, s.substr({ toString: function() { return '1'; } }));


assertEquals(s.substring(s.length - 1), s.substr(-1));
assertEquals(s.substring(s.length - 1), s.substr(-1.2));
assertEquals(s.substring(s.length - 1), s.substr(-1.7));
assertEquals(s.substring(s.length - 2), s.substr(-2));
assertEquals(s.substring(s.length - 2), s.substr(-2.3));
assertEquals(s.substring(s.length - 2, s.length - 1), s.substr(-2, 1));
assertEquals(s, s.substr(-100));
assertEquals('abc', s.substr(-100, 3));
assertEquals(s1, s.substr(-s.length + 1));

// assertEquals('', s.substr(0, void 0)); // smjs and rhino
assertEquals('abcdefghijklmn', s.substr(0, void 0));  // kjs and v8
assertEquals('', s.substr(0, null));
assertEquals(s, s.substr(0, String(s.length)));
assertEquals('a', s.substr(0, true));


// Test substrings of different lengths and alignments.
// First ASCII.
var x = "ASCII";
for (var i = 0; i < 25; i++) {
  x += (i >> 4).toString(16) + (i & 0x0f).toString(16);
}
/x/.exec(x);  // Try to force a flatten.
for (var i = 5; i < 25; i++) {
  for (var j = 0; j < 25; j++) {
    var z = x.substring(i, i+j);
    var w = Math.random() * 42;  // Allocate something new in new-space.
    assertEquals(j, z.length);
    for (var k = 0; k < j; k++) {
      assertEquals(x.charAt(i+k), z.charAt(k));
    }
  }
}
// Then two-byte strings.
x = "UC16\u2028";  // Non-ascii char forces two-byte string.
for (var i = 0; i < 25; i++) {
  x += (i >> 4).toString(16) + (i & 0x0f).toString(16);
}
/x/.exec(x);  // Try to force a flatten.
for (var i = 5; i < 25; i++) {
  for (var j = 0; j < 25; j++) {
    var z = x.substring(i, i + j);
    var w = Math.random() * 42;  // Allocate something new in new-space.
    assertEquals(j, z.length);
    for (var k = 0; k < j; k++) {
      assertEquals(x.charAt(i+k), z.charAt(k));
    }
  }
}

// Keep creating strings to to force allocation failure on substring creation.
var x = "0123456789ABCDEF";
for (var i = 0; i < 8; i++) x += x;
var xl = x.length;
var cache = [];
for (var i = 0; i < 1000; i++) {
  var z = x.substring(i % xl);
  assertEquals(xl - (i % xl), z.length);
  cache.push(z);
}


// Same with two-byte strings
var x = "\u2028123456789ABCDEF";
for (var i = 0; i < 8; i++) x += x;
var xl = x.length;
var cache = [];
for (var i = 0; i < 1000; i++) {
  var z = x.substring(i % xl);
  assertEquals(xl - (i % xl), z.length);
  cache.push(z);
}

// Substring of substring.
var cache = [];
var last = x;
var offset = 0;
for (var i = 0; i < 64; i++) {
  var z = last.substring(i);
  last = z;
  cache.push(z);
  offset += i;
}
for (var i = 63; i >= 0; i--) {
  var z = cache.pop();
  assertTrue(/\u2028123456789ABCDEF/.test(z));
  assertEquals(xl - offset, z.length);
  assertEquals(x.charAt(i*(i+1)/2), z.charAt(0));
  offset -= i;
}

// Test charAt for different strings.
function f(s1, s2, s3, i) {
  assertEquals(String.fromCharCode(97+i%11), s1.charAt(i%11));
  assertEquals(String.fromCharCode(97+i%11), s2.charAt(i%11));
  assertEquals(String.fromCharCode(98+i%11), s3.charAt(i%11));
  assertEquals(String.fromCharCode(101), s3.charAt(3));
}

flat = "abcdefghijkl12345";
cons = flat + flat.toUpperCase();
slice = "abcdefghijklmn12345".slice(1, -1);
for ( var i = 0; i < 1000; i++) {
  f(flat, cons, slice, i);
}
flat = "abcdefghijkl1\u20232345";
cons = flat + flat.toUpperCase();
slice = "abcdefghijklmn1\u20232345".slice(1, -1);
for ( var i = 0; i < 1000; i++) {
  f(flat, cons, slice, i);
}

// Short substrings.
flat = "abcdefghijkl12345";
cons = flat + flat.toUpperCase();
/x/.exec(cons);  // Flatten cons
slice = "abcdefghijklmn12345".slice(1, -1);
assertEquals("cdefg", flat.substr(2, 5));
assertEquals("cdefg", cons.substr(2, 5));
assertEquals("cdefg", slice.substr(1, 5));

flat = "abc\u1234defghijkl12345";
cons = flat + flat.toUpperCase();
/x/.exec(cons);  // Flatten cons
slice = "abc\u1234defghijklmn12345".slice(1, -1);
assertEquals("c\u1234def", flat.substr(2, 5));
assertEquals("c\u1234def", cons.substr(2, 5));
assertEquals("c\u1234def", slice.substr(1, 5));

// Concatenate substrings.
var ascii = 'abcdefghijklmnop';
var utf = '\u03B1\u03B2\u03B3\u03B4\u03B5\u03B6\u03B7\u03B8\u03B9\u03BA\u03BB';
assertEquals("klmno", ascii.substring(10,15) + ascii.substring(16));
assertEquals("\u03B4\u03B7", utf.substring(3,4) + utf.substring(6,7));
assertEquals("klp", ascii.substring(10,12) + ascii.substring(15,16));
assertEquals("\u03B1\u03B4\u03B5", utf.substring(0,1) + utf.substring(5,3));
assertEquals("", ascii.substring(16) + utf.substring(16));
assertEquals("bcdef\u03B4\u03B5\u03B6\u03B7\u03B8\u03B9",
    ascii.substring(1,6) + utf.substring(3,9));
assertEquals("\u03B4\u03B5\u03B6\u03B7\u03B8\u03B9abcdefghijklmnop",
    utf.substring(3,9) + ascii);
assertEquals("\u03B2\u03B3\u03B4\u03B5\u03B4\u03B5\u03B6\u03B7",
    utf.substring(5,1) + utf.substring(3,7));

// Externalizing strings.
var a = "internalized dummy";
a = "123456789" + "qwertyuiopasdfghjklzxcvbnm";
var b = "23456789qwertyuiopasdfghjklzxcvbn"
assertEquals(a.slice(1,-1), b);

assertTrue(isOneByteString(a));
externalizeString(a, true);
assertFalse(isOneByteString(a));

assertEquals(a.slice(1,-1), b);
assertTrue(/3456789qwe/.test(a));
assertEquals(5, a.indexOf("678"));
assertEquals("12345", a.split("6")[0]);

// Create a slice with an external string as parent string.
var c = a.slice(1,-1);

function test_crankshaft() {
  for (var i = 0; i < 20; i++) {
    assertEquals(b.charAt(i), a.charAt(i + 1));
    assertEquals(b.charAt(i), c.charAt(i));
    assertEquals(b.charAt(4), c.charAt(4));
    assertTrue(/3456789qwe/.test(c));
    assertEquals(4, c.indexOf("678"));
    assertEquals("2345", c.split("6")[0]);
  }
}

test_crankshaft();
%OptimizeFunctionOnNextCall(test_crankshaft);
test_crankshaft();

var s1 = "12345678901234567890";
var s2 = "abcdefghijklmnopqrstuvwxyz";
var c1 = s1 + s2;
var c2 = s1 + c1 + s2;
assertEquals("234567890123456789", c1.substring(1, 19));
assertEquals("bcdefghijklmno", c1.substring(21, 35));
assertEquals("2345678901234567890abcdefghijklmno", c1.substring(1, 35));
assertEquals("234567890123456789", c2.substring(1, 19));
assertEquals("bcdefghijklmno", c2.substring(41, 55));
assertEquals("2345678901234567890abcdefghijklmno", c2.substring(21, 55));