Specific expression types

src/ol/expression/expression.js

@@ -1,4 +1,10 @@
-goog.provide('ol.expression');
+goog.provide('ol.expression.BooleanLiteral');
+goog.provide('ol.expression.Expression');
+goog.provide('ol.expression.Identifier');
+goog.provide('ol.expression.Not');
+goog.provide('ol.expression.NullLiteral');
+goog.provide('ol.expression.NumericLiteral');
+goog.provide('ol.expression.StringLiteral');
 
 
 /**
@@ -10,16 +16,178 @@ goog.provide('ol.expression');
  */
 
 
+
 /**
- * @enum {string}
+ * @constructor
  */
-ol.expression.Syntax = {
-  BINARY_EXPRESSION: 'BinaryExpression',
-  CALL_EXPRESSION: 'CallExpression',
-  IDENTIFIER: 'Identifier',
-  LITERAL: 'Literal',
-  LOGICAL_EXPRESSION: 'LogicalExpression',
-  MEMBER_EXPRESSION: 'MemberExpression',
-  PROPERTY: 'Property', // dot notation only
-  UNARY_EXPRESSION: 'UnaryExpression' // only with logical not
+ol.expression.Expression = function() {};
+
+
+/**
+ * Evaluate the expression and return the result.
+ *
+ * @param {Object} scope Evaluation scope.  All properties of this object
+ *     will be available as variables when evaluating the expression.
+ * @return {string|number|boolean|null} Result of the expression.
+ */
+ol.expression.Expression.prototype.evaluate = goog.abstractMethod;
+
+
+
+/**
+ * A boolean literal expression (e.g. `true`).
+ *
+ * @constructor
+ * @extends {ol.expression.Expression}
+ * @param {boolean} value A boolean value.
+ */
+ol.expression.BooleanLiteral = function(value) {
+
+  /**
+   * @type {boolean}
+   * @private
+   */
+  this.value_ = value;
+
+};
+goog.inherits(ol.expression.BooleanLiteral, ol.expression.Expression);
+
+
+/**
+ * @inheritDoc
+ */
+ol.expression.BooleanLiteral.prototype.evaluate = function(scope) {
+  return this.value_;
+};
+
+
+
+/**
+ * An identifier expression (e.g. `foo`).
+ *
+ * @constructor
+ * @extends {ol.expression.Expression}
+ * @param {string} name An identifier name.
+ */
+ol.expression.Identifier = function(name) {
+
+  /**
+   * @type {string}
+   * @private
+   */
+  this.name_ = name;
+
+};
+goog.inherits(ol.expression.Identifier, ol.expression.Expression);
+
+
+/**
+ * @inheritDoc
+ */
+ol.expression.Identifier.prototype.evaluate = function(scope) {
+  return scope[this.name_];
+};
+
+
+
+/**
+ * A logical not expression (e.g. `!foo`).
+ *
+ * @constructor
+ * @extends {ol.expression.Expression}
+ * @param {ol.expression.Expression} expr Expression to negate.
+ */
+ol.expression.Not = function(expr) {
+
+  /**
+   * @type {ol.expression.Expression}
+   * @private
+   */
+  this.expr_ = expr;
+
+};
+goog.inherits(ol.expression.Not, ol.expression.Expression);
+
+
+/**
+ * @inheritDoc
+ */
+ol.expression.Not.prototype.evaluate = function(scope) {
+  return !this.expr_.evaluate(scope);
+};
+
+
+
+/**
+ * A numeric literal expression (e.g. `42`).
+ *
+ * @constructor
+ * @extends {ol.expression.Expression}
+ * @param {number} value A numeric value.
+ */
+ol.expression.NumericLiteral = function(value) {
+
+  /**
+   * @type {number}
+   * @private
+   */
+  this.value_ = value;
+
+};
+goog.inherits(ol.expression.NumericLiteral, ol.expression.Expression);
+
+
+/**
+ * @inheritDoc
+ */
+ol.expression.NumericLiteral.prototype.evaluate = function(scope) {
+  return this.value_;
+};
+
+
+
+/**
+ * A null literal expression (i.e. `null`).
+ *
+ * @constructor
+ * @extends {ol.expression.Expression}
+ */
+ol.expression.NullLiteral = function() {
+};
+goog.inherits(ol.expression.NullLiteral, ol.expression.Expression);
+
+
+/**
+ * @inheritDoc
+ */
+ol.expression.NullLiteral.prototype.evaluate = function(scope) {
+  return null;
+};
+
+
+
+/**
+ * A string literal expression (e.g. `"chicken"`).
+ *
+ * @constructor
+ * @extends {ol.expression.Expression}
+ * @param {string} value A string.
+ */
+ol.expression.StringLiteral = function(value) {
+
+  /**
+   * @type {string}
+   * @private
+   */
+  this.value_ = value;
+
+};
+goog.inherits(ol.expression.StringLiteral, ol.expression.Expression);
+
+
+/**
+ * @inheritDoc
+ */
+ol.expression.StringLiteral.prototype.evaluate = function(scope) {
+  return this.value_;
 };

test/spec/ol/expression/expression.test.js

@@ -0,0 +1,73 @@
+goog.provide('ol.test.expression.Expression');
+
+
+describe('ol.expression.BooleanLiteral', function() {
+
+  describe('constructor', function() {
+    var expr = new ol.expression.BooleanLiteral(true);
+    expect(expr).to.be.a(ol.expression.Expression);
+    expect(expr).not.to.be.a(ol.expression.BooleanLiteral);
+  });
+
+});
+
+
+describe('ol.expression.Identifier', function() {
+
+  describe('constructor', function() {
+    var expr = new ol.expression.Identifier('foo');
+    expect(expr).to.be.a(ol.expression.Expression);
+    expect(expr).to.be.a(ol.expression.Identifier);
+  });
+
+});
+
+describe('ol.expression.Not', function() {
+
+  describe('constructor', function() {
+    var expr = new ol.expression.Not(
+        new ol.expression.BooleanLiteral(true));
+    expect(expr).to.be.a(ol.expression.Expression);
+    expect(expr).to.be.a(ol.expression.Not);
+  });
+
+});
+
+describe('ol.expression.NullLiteral', function() {
+
+  describe('constructor', function() {
+    var expr = new ol.expression.NullLiteral();
+    expect(expr).to.be.a(ol.expression.Expression);
+    expect(expr).to.be.a(ol.expression.NullLiteral);
+  });
+
+});
+
+describe('ol.expression.NumericLiteral', function() {
+
+  describe('constructor', function() {
+    var expr = new ol.expression.NumericLiteral(42);
+    expect(expr).to.be.a(ol.expression.Expression);
+    expect(expr).to.be.a(ol.expression.NumericLiteral);
+  });
+
+});
+
+describe('ol.expression.StringLiteral', function() {
+
+  describe('constructor', function() {
+    var expr = new ol.expression.StringLiteral('bar');
+    expect(expr).to.be.a(ol.expression.Expression);
+    expect(expr).to.be.a(ol.expression.StringLiteral);
+  });
+
+});
+
+
+goog.require('ol.expression.BooleanLiteral');
+goog.require('ol.expression.Expression');
+goog.require('ol.expression.Identifier');
+goog.require('ol.expression.Not');
+goog.require('ol.expression.NullLiteral');
+goog.require('ol.expression.NumericLiteral');
+goog.require('ol.expression.StringLiteral');