Detect conflict between two path patterns.

pathpatterns.ts

// PathPattern codes

// "/hoge/:id"
// "/hoge/fuga/:name"
// "/hoge/fuga/hoho/:value"
// "/hoge/:param/fuga"
//
// :name = fuga AND :param = fuga
// 
// PathPattern =  ( Constant | Variable )を0個以上繰り返したもの
// 
// 2つのPathPattern型の値が「衝突」するか判定するコードを書きたい

type Variable = ":variable";

type Constant = string;

type PatternElement = Constant | Variable;

type PathPattern = PatternElement[];

const parsePathPattern = (path :string) : PathPattern => {
  return [];
};

// Tests

type PathPatternTestCase = {
  left : PathPattern,
  right: PathPattern,
  conflict: boolean,
};

const isVariable = (arg: any): arg is Variable => arg === ":variable";

// conflicts returns true iff left & right patterns conflicts.
const conflicts = (left: PathPattern, right:PathPattern):boolean => {
  if (left.length !== right.length) {
    return false; 
  }
  for (let i = 0; i < left.length; i++) {
    if (isVariable(left[i])) continue;
    if (isVariable(right[i])) continue;
    if (left[i] === right[i]) continue;
    return false;
  }
  return true;
};

const test = () => {
  console.log("TEST STARTED.");
  const testcases = [
    {
      left: ["hoge","fuga"],
      right:["hoge","fuga"],
      conflict: true,
    },
    {
      left: ["hoge",":variable"],
      right:["hoge","fuga"],
      conflict: true,
    },
    {
      left: ["hoge",":variable"],
      right:["hoge","fuga","hoho"],
      conflict: false,
    },
        {
      left: ["hoge","fuga", ":variable"],
      right:["hoge",":variable","hoho"],
      conflict: true,
    },
  ];
  for (let i = 0; i < testcases.length; i++ ) {
    const testcase = testcases[i];
    if (conflicts(testcase.left, testcase.right) !== testcase.conflict) {
      console.error(`FAIL in case ${i}`, testcase);
    } else { console.log(`SUCCESS case ${i}`);}
  } 
};

test();