gistfile1.js

// . must match a single character
// * may match zero or more characters
// a-z must match that character
// order matters

assert(".", "a", true);
assert("..", "aa", true);
assert("..", "a", false);
assert("abc", "abc", true);
assert("ab", "abc", false);
assert("ab.", "abc", true);
assert("ab.", "abcd", false);
assert("ab..", "abcd", true);
assert("abc.", "abc", false);
assert(".c.", "acd", true);
assert("*", "", true);
assert("**", "", true);
assert("*c", "aaaac", true);
assert("*c*", "aaaac", true);
assert("*c.", "aaaac", false);
assert("a*b", "abc", false);
assert("a*", "abc", true);
assert("abc*", "abc", true);
assert("*c", "abc", true);
assert("a*b*c", "abac", true);
assert("a*b****.c", "abac", true);
assert("a*b****.c", "cab", false);
assert(".*b*.", "abc", true);
assert("*b*", "abc", true);
assert("*.b.*", "abc", true);
assert(".b.", "abc", true);
assert(".*c*.", "abc", false);
assert("*c*", "abc", true);
assert("*.c.*", "abc", false);
assert(".c.", "abc", false);
assert("abc", "ab", false);
assert("ab.....", ".......", false);
assert(".......", "...ab..", true);
assert("***ab****", "...ab...", true);
assert("***ab****", "ab", true);
assert("***ab***.", "ab", false);
assert("*.*", "", false);
assert("*.*", "a", true);
assert("*.*.*", "a", false);
assert("*.*.*", "ab", true);

function isMatch(pattern, sample) {
  console.log("==============================================")
  console.log('Testing match of ' + pattern + " to " + sample)

  // For the purpose of matching, disregard stars in pattern
  patternWithoutStars = pattern.replace(/\*/g, "");

  if(patternWithoutStars.length > sample.length) {
    console.log("Fails, patterns may not have more non-star characters than their sample.")
    return false;
  }

  var lastMatch = -1;

  for(var i = 0; i < patternWithoutStars.length; i++) {

    var patternChar = patternWithoutStars[i];

    // Test against a string of '.'s or the actual string
    var testAgainst;
    if(patternChar == ".") {
      var testAgainst = sample.replace(/\S/g, ".");
    }
    else {
      var testAgainst = sample;
    }

    // Find index of the match, beginning at index of last match
    console.log("Checking to see if " + patternChar + " is in remainder of string: " + testAgainst.slice(lastMatch + 1))
    lastMatch = testAgainst.indexOf(patternChar, lastMatch + 1);

    if(lastMatch == -1) {
      console.log("Didn't find it.")
      return false;
    }

    console.log(patternChar + " matches " + testAgainst[lastMatch])
  }

  // Cover edge case where an additional letter is in pattern, but have reached end of sample
  if(lastMatch < sample.length - 1 && pattern[pattern.length - 1] != "*") {
    console.log("Had trailing letters that were not matched and no star was on original pattern. Failing.")
    return false;
  }

  console.log("Match successful")

  return true;
}

function assert(pattern, sample, expected) {
  var result = isMatch(pattern, sample)
  if(result != expected) {
    throw new Error(pattern + " and " + sample + " should be: " + expected + " but got " + result)
  }
}