feat: added interpolation

feat: added interpolation

Author: kantord

src/interpolation.js

@@ -0,0 +1,26 @@
+const format_string = (input, state) => {
+  if (Object.entries(state).length === 0) return input
+  const first_key = Object.keys(state)[0]
+  const copy = Object.assign({}, state)
+  delete copy[first_key]
+  return format_string(input.replace('${' + first_key + '}', state[first_key]), copy)
+}
+
+const format_array = (input, state) => {
+  return input.map(item => format_value(item, state))
+}
+
+const format_value = (input, state) => {
+  if (input instanceof Array) return format_array(input, state)
+  if (typeof input === "string") return format_string(input, state)
+  if (typeof input === "object") return format_object(input, state)
+  return input
+}
+
+const format_object = (input, state) => {
+  return Object.assign({}, ...Object.entries(input).map(
+    ([key, value]) => ({[format_string(key, state)]: format_value(value, state)})
+  ))
+}
+
+export { format_string , format_array, format_value, format_object }

src/interpolation.test.js

@@ -0,0 +1,52 @@
+const module = require('./interpolation.js')
+
+const string_tests = [
+  ['foo', 'foo', {}],
+  ['Hello World!', 'Hello World!', {}],
+  ['Hello ${name}', 'Hello World!', {'name': 'World!'}],
+  ['Hello ${name}!', 'Hello Person!', {'name': 'Person'}],
+  ['${greeting} ${name}!', 'Hola Person!', {'name': 'Person', 'greeting': 'Hola'}],
+  ['${foo} ${bar}!', 'Hola Person!', {'bar': 'Person', 'foo': 'Hola'}],
+]
+
+const array_tests = [
+  [[], [], {}],
+  [['Hello ${name}!'], ['Hello World!'], {'name': 'World'}],
+  [['Hello ${foo}!'], ['Hello World!'], {'foo': 'World'}],
+  [['Hello ${foo}!', 'Hello ${foo}!'], ['Hello World!', 'Hello World!'], {'foo': 'World'}],
+  [['Hello ${foo}!', ['Hello ${foo}!']], ['Hello World!', ['Hello World!']], {'foo': 'World'}],
+  [['Hello ${foo}!', [{'${foo}': 42}]], ['Hello World!', [{'World': 42}]], {'foo': 'World'}],
+]
+
+const static_tests = [
+  [42, 42, {}],
+  [false, false, {}],
+  [889593.234234, 889593.234234, {}],
+]
+
+const object_tests = [
+  [{}, {}, {}],
+  [{'foo': '${bar}'}, {'foo': 'hello'}, {'bar': 'hello'}],
+  [{'foo': '${bar}', 'baz': '${asd}'}, {'foo': 'hello', 'baz': '33'}, {'bar': 'hello', 'asd': '33'}],
+  [{'${bar}': '${bar}', 'baz': '${asd}'}, {'hello': 'hello', 'baz': '33'}, {'bar': 'hello', 'asd': '33'}],
+  [{'${bar}': ['${bar}'], 'baz': '${asd}'}, {'hello': ['hello'], 'baz': '33'}, {'bar': 'hello', 'asd': '33'}],
+]
+
+const tests = [
+  ['String interpolation', 'format_string', [string_tests]],
+  ['Array interpolation', 'format_array', [array_tests]],
+  ['Value interpolation', 'format_value', [string_tests, array_tests, static_tests, object_tests]],
+  ['Object interpolation', 'format_object', [object_tests]],
+]
+
+tests.forEach(([test_suite_name, function_name, test_sets]) =>
+  describe(test_suite_name, () => {
+    test_sets.forEach(test_set =>
+      test_set.forEach(([input, output, state]) => 
+        it(`${[JSON.stringify(input), JSON.stringify(output), JSON.stringify(state)]}`, () => {
+          module[function_name](input, state).should.deepEqual(output)
+        })
+      )
+    )
+  })
+)