feat: add sortBy function

docs(gh-pages): documentation for sortBy

style(interpreter-test-js): fix style issues

docs/index.md

@@ -1,4 +1,4 @@
-# emuto ![build](https://img.shields.io/travis/kantord/emuto/master.svg) ![Codecov](https://img.shields.io/codecov/c/github/kantord/emuto/master.svg)  ![npm bundle size (minified + gzip)](https://img.shields.io/bundlephobia/minzip/emuto.svg)
+# emuto ![build](https://img.shields.io/travis/kantord/emuto/master.svg) ![Codecov](https://img.shields.io/codecov/c/github/kantord/emuto/master.svg) ![npm bundle size (minified + gzip)](https://img.shields.io/bundlephobia/minzip/emuto.svg)
 
 emuto is a lightweight JSON processor inspired by and nearly porting [jq](https://stedolan.github.io/jq/)
 
@@ -100,6 +100,16 @@ Output:
 
 Alternatively, you can also use this syntax: `["Hello", "World!"] | map \ {"word": $}`
 
+#### `sortBy \`
+
+Takes an array as input and sorts it using the supplied function.
+
+For example:
+
+```
+sortBy $ => .age | map $ => .name
+```
+
 ### Chaining filters
 
 You can combine two filters by using the pipe syntax, e. q. `.foo | .bar`

src/__tests__/__snapshots__/interpreter.test.js.snap

@@ -59,6 +59,8 @@ exports[`interpreter correct target code null 1`] = `"(function(_) { return (fun
 
 exports[`interpreter correct target code null: true 1`] = `"(function(_) { return (function(input) { return [null,true]})})"`;
 
+exports[`interpreter correct target code sortBy \\.age | map \\.name 1`] = `"(function(_) { return (function(input) { return (function (input) {return (_.map(function(input) {return input.name})(input))})((_.sortBy(function(input) {return input.age})(input)))})})"`;
+
 exports[`interpreter correct target code true 1`] = `"(function(_) { return (function(input) { return true})})"`;
 
 exports[`interpreter correct target tree $ 1`] = `
@@ -1402,6 +1404,43 @@ Object {
 }
 `;
 
+exports[`interpreter correct target tree sortBy \\.age | map \\.name 1`] = `
+Object {
+  "status": true,
+  "value": Object {
+    "name": "pipe",
+    "value": Object {
+      "left": Object {
+        "name": "functionCallLambda",
+        "value": Object {
+          "left": Object {
+            "name": "identifier",
+            "value": "sortBy",
+          },
+          "right": Object {
+            "name": "inputProp",
+            "value": ".age",
+          },
+        },
+      },
+      "right": Object {
+        "name": "functionCallLambda",
+        "value": Object {
+          "left": Object {
+            "name": "identifier",
+            "value": "map",
+          },
+          "right": Object {
+            "name": "inputProp",
+            "value": ".name",
+          },
+        },
+      },
+    },
+  },
+}
+`;
+
 exports[`interpreter correct target tree true 1`] = `
 Object {
   "status": true,

src/__tests__/builtins.test.js

@@ -1,6 +1,6 @@
 import builtIns from '../builtins'
 
-const { projection, join, map } = builtIns
+const { projection, join, map, sortBy } = builtIns
 
 describe('built ins', () => {
   describe('projection', () => {
@@ -45,4 +45,25 @@ describe('built ins', () => {
       expect(map(foo)(['Hello', 'World'])).toEqual(['foo', 'foo'])
     })
   })
+
+  describe('sortBy', () => {
+    it('returns correct value', () => {
+      const id = a => a; // eslint-disable-line
+      const foo = a => a.foo; // eslint-disable-line
+      expect(sortBy(id)(['c', 'a', 'b'])).toEqual(['a', 'b', 'c'])
+      expect(sortBy(foo)([{ foo: 3 }, { foo: -2 }, { foo: 0 }])).toEqual([
+        { foo: -2 },
+        { foo: 0 },
+        { foo: 3 }
+      ])
+    })
+
+    it('does not mutate original array', () => {
+      const id = a => a; // eslint-disable-line
+      const input = ['c', 'a', 'b']
+      const originalValue = input.slice()
+      sortBy(id)(input)
+      expect(input).toEqual(originalValue)
+    })
+  })
 })

src/__tests__/interpreter.test.js

@@ -158,6 +158,11 @@ const tests = [
   {
     sourceCode: `{"foo": [{"bar": "baz"}]} | $.foo[0].bar`,
     output: 'baz'
+  },
+  {
+    sourceCode: `sortBy \\.age | map \\.name`,
+    output: ['John', 'Mary'],
+    input: [{ name: 'John', age: 11 }, { name: 'Mary', age: 33 }]
   }
 ]
 

src/builtins.js

@@ -42,5 +42,14 @@ export default {
   ): string => input.join(separator),
   map: (f: mixed => mixed): ((Array<mixed>) => Array<mixed>) => (
     input: Array<mixed>
-  ): Array<mixed> => input.map(f)
+  ): Array<mixed> => input.map(f),
+  sortBy: (f: <T>(mixed) => T): ((Array<mixed>) => Array<mixed>) => (
+    input: Array<mixed>
+  ): Array<mixed> =>
+    input
+      .slice()
+      .sort(
+        (a: mixed, b: mixed): 1 | 0 | -1 =>
+          f(a) < f(b) ? -1 : f(a) > f(b) ? 1 : 0
+      )
 }