feat(expression): add support for conditional expression

src/Expressions/ConditionalExpression.js

@@ -0,0 +1,108 @@
+'use strict'
+
+/*
+ * edge
+ *
+ * (c) Harminder Virk <virk@adonisjs.com>
+ *
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+*/
+
+const BaseExpression = require('./BaseExpression')
+
+/**
+ * Conditional expression parses the shorthand if
+ * statement.
+ *
+ * @class ConditionalExpression
+ * @extends {BaseExpression}
+ * @constructor
+ *
+ * @example
+ * ```js
+ * username ? username : 'anonymous'
+ * ```
+ *
+ */
+class ConditionalExpression extends BaseExpression {
+  constructor (lexer) {
+    super(lexer)
+    this._tokens = {
+      members: [],
+      test: null,
+      consequent: null,
+      alternate: null,
+      wrapAlternate: false,
+      type: 'conditional'
+    }
+  }
+
+  /**
+   * Parses the expression. It is responsibility of the
+   * consumer to pass the right expression otherwise
+   * things will blow.
+   *
+   * @method parse
+   *
+   * @param  {Object} expression
+   *
+   * @return {void}
+   */
+  parse (expression) {
+    this._tokens.test = this._lexer.parse(expression.test)
+    this._tokens.consequent = this._lexer.parse(expression.consequent)
+    this._tokens.alternate = this._lexer.parse(expression.alternate)
+    this._tokens.wrapAlternate = expression.alternate.type === 'ConditionalExpression'
+  }
+
+  /**
+   * Returns the formatted string for the alternate part
+   * of the token
+   *
+   * @method testStatement
+   *
+   * @return {String}
+   */
+  testStatement () {
+    return this._convertToStatement(this._tokens.test, true)
+  }
+
+  /**
+   * Returns the formatted string for the alternate part
+   * of the token
+   *
+   * @method consequentStatement
+   *
+   * @return {String}
+   */
+  consequentStatement () {
+    return this._convertToStatement(this._tokens.consequent, true)
+  }
+
+  /**
+   * Returns the formatted string for the alternate part
+   * of the token
+   *
+   * @method alternateStatement
+   *
+   * @return {String}
+   */
+  alternateStatement () {
+    const alternateStatement = this._convertToStatement(this._tokens.alternate, true)
+    return this._tokens.wrapAlternate ? `(${alternateStatement})` : alternateStatement
+  }
+
+  /**
+   * Converts tokens into parsed statement
+   *
+   * @method toStatement
+   *
+   * @return {String}
+   */
+  toStatement () {
+    return `${this.testStatement()} ? ${this.consequentStatement()} : ${this.alternateStatement()}`
+  }
+}
+
+module.exports = ConditionalExpression

src/Expressions/index.js

@@ -18,5 +18,6 @@ module.exports = {
   AssignmentExpression: require('./AssignmentExpression'),
   CallExpression: require('./CallExpression'),
   UnaryExpression: require('./UnaryExpression'),
-  LogicalExpression: require('./LogicalExpression')
+  LogicalExpression: require('./LogicalExpression'),
+  ConditionalExpression: require('./ConditionalExpression')
 }

test/unit/conditional-expression.spec.js

@@ -0,0 +1,53 @@
+'use strict'
+
+/*
+ * edge
+ *
+ * (c) Harminder Virk <virk@adonisjs.com>
+ *
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+*/
+
+const test = require('japa')
+const esprima = require('esprima')
+const Lexer = require('../../src/Lexer')
+const ConditionalExpression = require('../../src/Expressions').ConditionalExpression
+const expressionsMixin = require('../../test-helpers/expression-mixin')
+
+test.group('Conditional Expression', (group) => {
+  group.beforeEach(() => {
+    this.exp = new ConditionalExpression(new Lexer())
+  })
+
+  expressionsMixin.bind(this)(test)
+
+  test('parse simple if shorthand', (assert) => {
+    const statement = `username ? username : 'anonymous'`
+    this.exp.parse(esprima.parse(statement).body[0].expression)
+    assert.equal(this.exp.tokens.test.type, 'source')
+    assert.equal(this.exp.tokens.test.value, 'username')
+    assert.equal(this.exp.tokens.consequent.type, 'source')
+    assert.equal(this.exp.tokens.consequent.value, 'username')
+    assert.equal(this.exp.tokens.alternate.type, 'string')
+    assert.equal(this.exp.tokens.alternate.value, 'anonymous')
+  })
+
+  test('convert simple if shorthand', (assert) => {
+    const statement = `username ? username : 'anonymous'`
+    this.exp.parse(esprima.parse(statement).body[0].expression)
+    assert.equal(this.exp.toStatement(), `this.context.resolve('username') ? this.context.resolve('username') : 'anonymous'`)
+  })
+
+  test('convert if shorthand with logical operator', (assert) => {
+    const statement = `username === 'virk' ? username : 'anonymous'`
+    this.exp.parse(esprima.parse(statement).body[0].expression)
+    assert.equal(this.exp.toStatement(), `this.context.resolve('username') === 'virk' ? this.context.resolve('username') : 'anonymous'`)
+  })
+
+  test('convert if shorthand with nested logical operator', (assert) => {
+    const statement = `username ? username : (session ? session.username : 'anonymous')`
+    this.exp.parse(esprima.parse(statement).body[0].expression)
+    assert.equal(this.exp.toStatement(), `this.context.resolve('username') ? this.context.resolve('username') : (this.context.resolve('session') ? this.context.accessChild(this.context.resolve('session'), ['username']) : 'anonymous')`)
+  })
+})