v8/test/mjsunit/regress/regress-2437.js

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// Summary of the spec: lastIndex is reset to 0 if
// - a regexp fails to match, regardless of global or non-global.
// - a global regexp is used in a function that returns multiple results,
//   such as String.prototype.replace or String.prototype.match, since it
//   repeats the regexp until it fails to match.
// Otherwise lastIndex is only set when a global regexp matches, to the index
// after the match.

// Test Regexp.prototype.exec
r = /a/;
r.lastIndex = 1;
r.exec("zzzz");
assertEquals(0, r.lastIndex);

// Test Regexp.prototype.test
r = /a/;
r.lastIndex = 1;
r.test("zzzz");
assertEquals(0, r.lastIndex);

// Test String.prototype.match
r = /a/;
r.lastIndex = 1;
"zzzz".match(r);
assertEquals(0, r.lastIndex);

// Test String.prototype.replace with atomic regexp and empty string.
r = /a/;
r.lastIndex = 1;
"zzzz".replace(r, "");
assertEquals(0, r.lastIndex);

// Test String.prototype.replace with non-atomic regexp and empty string.
r = /\d/;
r.lastIndex = 1;
"zzzz".replace(r, "");
assertEquals(0, r.lastIndex);

// Test String.prototype.replace with atomic regexp and non-empty string.
r = /a/;
r.lastIndex = 1;
"zzzz".replace(r, "a");
assertEquals(0, r.lastIndex);

// Test String.prototype.replace with non-atomic regexp and non-empty string.
r = /\d/;
r.lastIndex = 1;
"zzzz".replace(r, "a");
assertEquals(0, r.lastIndex);

// Test String.prototype.replace with replacement function
r = /a/;
r.lastIndex = 1;
"zzzz".replace(r, function() { return ""; });
assertEquals(0, r.lastIndex);

// Regexp functions that returns multiple results:
// A global regexp always resets lastIndex regardless of whether it matches.
r = /a/g;
r.lastIndex = -1;
"0123abcd".replace(r, "x");
assertEquals(0, r.lastIndex);

r.lastIndex = -1;
"01234567".replace(r, "x");
assertEquals(0, r.lastIndex);

r.lastIndex = -1;
"0123abcd".match(r);
assertEquals(0, r.lastIndex);

r.lastIndex = -1;
"01234567".match(r);
assertEquals(0, r.lastIndex);

// A non-global regexp resets lastIndex iff it does not match.
r = /a/;
r.lastIndex = -1;
"0123abcd".replace(r, "x");
assertEquals(-1, r.lastIndex);

r.lastIndex = -1;
"01234567".replace(r, "x");
assertEquals(0, r.lastIndex);

r.lastIndex = -1;
"0123abcd".match(r);
assertEquals(-1, r.lastIndex);

r.lastIndex = -1;
"01234567".match(r);
assertEquals(0, r.lastIndex);

// Also test RegExp.prototype.exec and RegExp.prototype.test
r = /a/g;
r.lastIndex = 1;
r.exec("01234567");
assertEquals(0, r.lastIndex);

r.lastIndex = 1;
r.exec("0123abcd");
assertEquals(5, r.lastIndex);

r = /a/;
r.lastIndex = 1;
r.exec("01234567");
assertEquals(0, r.lastIndex);

r.lastIndex = 1;
r.exec("0123abcd");
assertEquals(1, r.lastIndex);

r = /a/g;
r.lastIndex = 1;
r.test("01234567");
assertEquals(0, r.lastIndex);

r.lastIndex = 1;
r.test("0123abcd");
assertEquals(5, r.lastIndex);

r = /a/;
r.lastIndex = 1;
r.test("01234567");
assertEquals(0, r.lastIndex);

r.lastIndex = 1;
r.test("0123abcd");
assertEquals(1, r.lastIndex);