expose tokens to regexp/function methods

Readme.md

@@ -163,6 +163,13 @@ console.log(result)
 
 **Note:** The generated function will throw on any invalid input. It will execute all necessary checks to ensure the generated path is valid. This method only works with strings.
 
+### Working with Tokens
+
+Path-To-RegExp exposes the two functions used internally that accept an array of tokens.
+
+* `pathToRegexp.tokensToRegExp(tokens, options)` Transform an array of tokens into a matching regular expression.
+* `pathToRegexp.tokensToFunction(tokens)` Transform an array of tokens into a path generator function.
+
 ## Compatibility with Express <= 4.x
 
 Path-To-RegExp breaks compatibility with Express <= 4.x in a few ways:

index.js

@@ -6,6 +6,8 @@ var isarray = require('isarray')
 module.exports = pathToRegexp
 module.exports.parse = parse
 module.exports.compile = compile
+module.exports.tokensToFunction = tokensToFunction
+module.exports.tokensToRegExp = tokensToRegExp
 
 /**
  * The main path matching regexp utility.
@@ -96,12 +98,20 @@ function parse (str) {
  * @return {Function}
  */
 function compile (str) {
-  var keys = parse(str)
+  return tokensToFunction(parse(str))
+}
+
+/**
+ * Expose a method for transforming tokens into the path function.
+ */
+function tokensToFunction (tokens) {
+  // Compile all the tokens into regexps.
+  var matches = new Array(tokens.length)
 
   // Compile all the patterns before compilation.
-  for (var i = 0; i < keys.length; i++) {
-    if (typeof keys[i] === 'object') {
-      keys[i].regexp = new RegExp('^' + keys[i].pattern + '$')
+  for (var i = 0; i < tokens.length; i++) {
+    if (typeof tokens[i] === 'object') {
+      matches[i] = new RegExp('^' + tokens[i].pattern + '$')
     }
   }
 
@@ -110,8 +120,8 @@ function compile (str) {
 
     obj = obj || {}
 
-    for (var i = 0; i < keys.length; i++) {
-      var key = keys[i]
+    for (var i = 0; i < tokens.length; i++) {
+      var key = tokens[i]
 
       if (typeof key === 'string') {
         path += key
@@ -143,7 +153,7 @@ function compile (str) {
         }
 
         for (var j = 0; j < value.length; j++) {
-          if (!key.regexp.test(value[j])) {
+          if (!matches[i].test(value[j])) {
             throw new TypeError('Expected all "' + key.name + '" to match "' + key.pattern + '"')
           }
 
@@ -153,7 +163,7 @@ function compile (str) {
         continue
       }
 
-      if (!key.regexp.test(value)) {
+      if (!matches[i].test(value)) {
         throw new TypeError('Expected "' + key.name + '" to match "' + key.pattern + '"')
       }
 
@@ -262,11 +272,35 @@ function arrayToRegexp (path, keys, options) {
  * @return {RegExp}
  */
 function stringToRegexp (path, keys, options) {
+  var tokens = parse(path)
+  var re = tokensToRegExp(tokens, options)
+
+  // Attach keys back to the regexp.
+  for (var i = 0; i < tokens.length; i++) {
+    if (typeof tokens[i] !== 'string') {
+      keys.push(tokens[i])
+    }
+  }
+
+  return attachKeys(re, keys)
+}
+
+/**
+ * Expose a function for taking tokens and returning a RegExp.
+ *
+ * @param  {Array}  tokens
+ * @param  {Array}  keys
+ * @param  {Object} options
+ * @return {RegExp}
+ */
+function tokensToRegExp (tokens, options) {
+  options = options || {}
+
   var strict = options.strict
   var end = options.end !== false
   var route = ''
-  var endsWithSlash = path.charAt(path.length - 1) === '/'
-  var tokens = parse(path)
+  var lastToken = tokens[tokens.length - 1]
+  var endsWithSlash = typeof lastToken === 'string' && /\/$/.test(lastToken)
 
   // Iterate over the tokens and create our regexp string.
   for (var i = 0; i < tokens.length; i++) {
@@ -278,9 +312,6 @@ function stringToRegexp (path, keys, options) {
       var prefix = escapeString(token.prefix)
       var capture = token.pattern
 
-      // Push non-string tokens into the keys array.
-      keys.push(token)
-
       if (token.repeat) {
         capture += '(?:' + prefix + capture + ')*'
       }
@@ -315,7 +346,7 @@ function stringToRegexp (path, keys, options) {
     route += strict && endsWithSlash ? '' : '(?=\\/|$)'
   }
 
-  return attachKeys(new RegExp('^' + route, flags(options)), keys)
+  return new RegExp('^' + route, flags(options))
 }
 
 /**

test.js

@@ -1647,6 +1647,22 @@ describe('path-to-regexp', function () {
     })
   })
 
+  describe('tokens', function () {
+    var tokens = pathToRegexp.parse(TEST_PATH)
+
+    it('should expose method to compile tokens to regexp', function () {
+      var re = pathToRegexp.tokensToRegExp(tokens)
+
+      expect(exec(re, '/user/123')).to.deep.equal(['/user/123', '123'])
+    })
+
+    it('should expose method to compile tokens to a path function', function () {
+      var fn = pathToRegexp.tokensToFunction(tokens)
+
+      expect(fn({ id: 123 })).to.equal('/user/123')
+    })
+  })
+
   describe('rules', function () {
     TESTS.forEach(function (test) {
       var path = test[0]