Refactored expression matching into Expression

erithmetic · erithmetic · commit 4e1dbeb5bb05 · 2011-10-07T11:57:15.000-04:00
diff --git a/lib/environment.js b/lib/environment.js
@@ -1,3 +1,5 @@
+var Expression = require('./expression');
+
 var cache = {};
 
 var Environment = module.exports = function(jsonObject, expression, options) {
@@ -114,71 +116,5 @@ Environment.prototype.slice = function(segment, expression, object, path) {
 Environment.prototype.match = function(expression, object, _vname) {
   if(object === null) return object;
 
-  if(/[>=<]/.test(expression))
-    return this.compareValue(expression, object);
-  else if(/[-+*\/]/.test(expression))
-    return this.computeValue(expression, object);
-  else if(/\./.test(expression))
-    return this.getProperty(expression, object);
-  else
-    throw new SyntaxError("jsonPath: invalid query syntax: " + expression);
-};
-
-Environment.prototype.compareValue = function(expression, object) {
-  return this.operate(object, expression, '>=<');
-};
-
-Environment.prototype.getProperty = function(expression, object) {
-  var parts = expression.match(/\.([^\s]+)/);
-  var rhs;
-  try {
-    rhs = JSON.parse('"' + parts[1] + '"');
-  }
-  catch(e) {
-    throw new SyntaxError("jsonPath: invalid property name: " + parts[1]);
-  }
-  return object[rhs];
-};
-
-Environment.prototype.getValue = function(expression) {
-  try {
-    return JSON.parse(expression);
-  }
-  catch(e) {
-    throw new SyntaxError("jsonPath: invalid right-hand-side value: " + expression);
-  }
-};
-
-Environment.prototype.computeValue = function(expression, object) {
-  return this.operate(object, expression, '-+*/');
-};
-
-Environment.prototype.operate = function(object, expression, operators) {
-  var regex = new RegExp("([^\(\)" + operators + "]+)([" + operators + "]+)([^\(\)]+)");
-  var parts = expression.match(regex);
-  var lhs = this.getProperty(parts[1], object);
-  var rhs = this.getValue(parts[3]);
-
-  switch(parts[2]) {
-  case '==':
-    return lhs == rhs;
-  case '>=':
-    return lhs >= rhs;
-  case '<=':
-    return lhs <= rhs;
-  case '>':
-    return lhs > rhs;
-  case '<':
-    return lhs < rhs;
-  case '-':
-    return lhs - rhs;
-  case '+':
-    return lhs + rhs;
-  case '*':
-    return lhs * rhs;
-  case '/':
-    return lhs / rhs;
-  default:
-    throw new SyntaxError("jsonPath: invalid query syntax: " + expression);
-  }
+  return Expression.execute(expression, object);
 };
diff --git a/lib/expression.js b/lib/expression.js
@@ -0,0 +1,63 @@
+var Expression = module.exports = {
+  execute: function(expression, object) {
+    if(/[>=<]/.test(expression))
+      return this.operate(object, expression, '>=<');
+    else if(/[-+*\/]/.test(expression))
+      return this.operate(object, expression, '-+*/');
+    else if(/\./.test(expression))
+      return this.getProperty(expression, object);
+    else
+      throw new SyntaxError("jsonPath: invalid query syntax: " + expression);
+  },
+
+  getProperty: function(expression, object) {
+    var parts = expression.match(/\.([^\s]+)/);
+    var rhs;
+    try {
+      rhs = JSON.parse('"' + parts[1] + '"');
+    }
+    catch(e) {
+      throw new SyntaxError("jsonPath: invalid property name: " + parts[1]);
+    }
+    return object[rhs];
+  },
+
+  getValue: function(expression) {
+    try {
+      return JSON.parse(expression);
+    }
+    catch(e) {
+      throw new SyntaxError("jsonPath: invalid right-hand-side value: " + expression);
+    }
+  },
+
+  operate: function(object, expression, operators) {
+    var regex = new RegExp("([^\(\)" + operators + "]+)([" + operators + "]+)([^\(\)]+)");
+    var parts = expression.match(regex);
+    var lhs = this.getProperty(parts[1], object);
+    var rhs = this.getValue(parts[3]);
+
+    switch(parts[2]) {
+    case '==':
+      return lhs == rhs;
+    case '>=':
+      return lhs >= rhs;
+    case '<=':
+      return lhs <= rhs;
+    case '>':
+      return lhs > rhs;
+    case '<':
+      return lhs < rhs;
+    case '-':
+      return lhs - rhs;
+    case '+':
+      return lhs + rhs;
+    case '*':
+      return lhs * rhs;
+    case '/':
+      return lhs / rhs;
+    default:
+      throw new SyntaxError("jsonPath: invalid query syntax: " + expression);
+    }
+  },
+};
diff --git a/test/environment-test.js b/test/environment-test.js
@@ -2,41 +2,16 @@ var assert = require('assert'),
     vows = require('vows'),
     Environment = require("../lib/environment");
 
-vows.describe('JSONPath').addBatch({
+vows.describe('Environment').addBatch({
   '#match': {
     topic: new Environment({}, '', {}),
 
-    'matches (@.length-1)': function(env) {
-      var obj = [1,2,3];
-      assert.equal(env.match('(@.length-1)', obj), 2);
-    },
-    'matches @.isbn': function(env) {
-      var obj = { isbn: 'abc123' };
-      assert.equal(env.match('@.isbn', obj), 'abc123');
-    },
-    'matches @.price<10 true': function(env) {
-      var obj = { price: 5 };
-      assert.isTrue(env.match('@.price<10', obj));
-    },
-    'matches @.price<10 false': function(env) {
-      var obj = { price: 10 };
-      assert.isFalse(env.match('@.price<10', obj));
-    },
-    'matches @.price==10 true': function(env) {
-      var obj = { price: 10 };
-      assert.isTrue(env.match('@.price==10', obj));
-    },
-    'matches @.price==10 false': function(env) {
-      var obj = { price: 11 };
-      assert.isFalse(env.match('@.price==10', obj));
-    },
     'returns null if there is nothing to match against': function(env) {
       assert.isNull(env.match('something', null));
     },
-    'throws a syntax error for invalid statements': function(env) {
-      assert.throws(function() {
-        env.match('oogabooga', {});
-      });
+    'matches the expression against the current object': function(env) {
+      var obj = { isbn: 'abc123' };
+      assert.equal(env.match('@.isbn', obj), 'abc123');
     }
   }
 }).export(module);
diff --git a/test/expression-test.js b/test/expression-test.js
@@ -0,0 +1,37 @@
+var assert = require('assert'),
+    vows = require('vows'),
+    Expression = require("../lib/expression");
+
+vows.describe('Expression').addBatch({
+  '.execute': {
+    'matches (@.length-1)': function(env) {
+      var obj = [1,2,3];
+      assert.equal(Expression.execute('(@.length-1)', obj), 2);
+    },
+    'matches @.isbn': function(env) {
+      var obj = { isbn: 'abc123' };
+      assert.equal(Expression.execute('@.isbn', obj), 'abc123');
+    },
+    'matches @.price<10 true': function(env) {
+      var obj = { price: 5 };
+      assert.isTrue(Expression.execute('@.price<10', obj));
+    },
+    'matches @.price<10 false': function(env) {
+      var obj = { price: 10 };
+      assert.isFalse(Expression.execute('@.price<10', obj));
+    },
+    'matches @.price==10 true': function(env) {
+      var obj = { price: 10 };
+      assert.isTrue(Expression.execute('@.price==10', obj));
+    },
+    'matches @.price==10 false': function(env) {
+      var obj = { price: 11 };
+      assert.isFalse(Expression.execute('@.price==10', obj));
+    },
+    'throws a syntax error for invalid statements': function(env) {
+      assert.throws(function() {
+        Expression.execute('oogabooga', {});
+      });
+    }
+  }
+}).export(module);
