Grammar, parser and model for queries

packages/composer-common/.eslintignore

@@ -3,4 +3,5 @@ node_modules
 out
 lib/introspect/parser.js
 lib/acl/parser.js
+lib/query/parser.js
 test/data

packages/composer-common/lib/query/orderby.js

@@ -0,0 +1,108 @@
+/*
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+'use strict';
+
+const IllegalModelException = require('../introspect/illegalmodelexception');
+const Sort = require('./sort');
+
+/**
+ * Defines the ORDER BY specification for a SELECT statement
+ *
+ * @private
+ * @class
+ * @memberof module:composer-common
+ */
+class OrderBy {
+
+    /**
+     * Create an OrderBy from an Abstract Syntax Tree. The AST is the
+     * result of parsing.
+     *
+     * @param {Select} select - the Select for this order by
+     * @param {string} ast - the AST created by the parser
+     * @throws {IllegalModelException}
+     */
+    constructor(select, ast) {
+        if(!select || !ast) {
+            throw new IllegalModelException('Invalid Select or AST');
+        }
+
+        this.ast = ast;
+        this.select = select;
+        this.process();
+    }
+
+    /**
+     * Visitor design pattern
+     * @param {Object} visitor - the visitor
+     * @param {Object} parameters  - the parameter
+     * @return {Object} the result of visiting or null
+     * @private
+     */
+    accept(visitor,parameters) {
+        return visitor.visit(this, parameters);
+    }
+
+    /**
+     * Returns the Select that owns this OrderBy.
+     *
+     * @return {Select} the owning Select
+     */
+    getSelect() {
+        return this.select;
+    }
+
+    /**
+     * Process the AST and build the model
+     *
+     * @throws {IllegalModelException}
+     * @private
+     */
+    process() {
+        this.sortCriteria = null;
+
+        if(this.ast.sort) {
+            this.sortCriteria = [];
+
+            for(let n=0; n < this.ast.sort.length; n++) {
+                this.sortCriteria.push( new Sort(this, this.ast.sort[n]));
+            }
+        }
+    }
+
+    /**
+     * Semantic validation of the structure of this select.
+     *
+     * @throws {IllegalModelException}
+     * @private
+     */
+    validate() {
+        // TODO (DCS) check that the fields we are sorting by exist!
+    }
+
+    /**
+     * Returns a new object representing this Query that is
+     * suitable for serializing as JSON.
+     * @return {Object} A new object suitable for serializing as JSON.
+     */
+    toJSON() {
+        let result = {
+            sortCriteria: this.sortCriteria.toJSON()
+        };
+        return result;
+    }
+}
+
+module.exports = OrderBy;