compare-empty-string.js

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// Test case to cover empty string comparison folding.

//

// MCompare can fold comparison with an empty string constant and replace it

// with |string.length <op> 0|.

const strings = [

  // Zero length string.

"",

  // Uncommon zero length strings.

  newString("", {external: true}),

  // Latin-1 strings.

  "a",

  "ä",

  "monkey",

  // Two-byte strings.

  "猿",

  "🐒",

  newString("monkey", {twoByte: true}),

];

const operators = [

  "==", "===", "!=", "!==",

  "<", "<=", ">=", ">",

];

for (let op of operators) {

  let lhs = x => `${x} ${op} ""`;

  let rhs = x => `"" ${op} ${x}`;

  for (let input of [lhs, rhs]) {

    let fn = Function("strings", `

      const expected = strings.map(x => {

        // Prevent Warp compilation when computing the expected results.

        with ({}) ;

        return ${input("x")};

});

      for (let i = 0; i < 200; ++i) {

        let idx = i % strings.length;

        let str = strings[idx];

        let res = ${input("str")};

        assertEq(res, expected[idx]);

`);

    fn(strings);