Ability to construct single JSON object. Refs #27

Ability to construct a single statement list node containing all the
statements parsed by the stream transform. Uses a second
transform available as createStitcher().

This transform separates each statement AST with a comma and
then wraps the entire list in a statement list node:

``` json
{
  "type": "statement",
  "variant": "list",
  "statement": []
}
```

Author: nwronski

lib/index.js

@@ -3,7 +3,7 @@
  */
 import { parse, SyntaxError as PegSyntaxError } from './parser';
 import { Tracer } from './tracer';
-import { SqliteParserTransform } from './streaming';
+import { SqliteParserTransform, SingleNodeTransform } from './streaming';
 
 export default function sqliteParser(source, options, callback) {
   const t = Tracer();
@@ -44,5 +44,9 @@ sqliteParser['createParser'] = function () {
   return new SqliteParserTransform();
 };
 
+sqliteParser['createStitcher'] = function () {
+  return new SingleNodeTransform();
+};
+
 sqliteParser['NAME'] = 'sqlite-parser';
 sqliteParser['VERSION'] = '@@VERSION';

lib/streaming.js

@@ -34,7 +34,7 @@ export class SqliteParserTransform extends Transform {
       if (nextAst != null) {
         let serialized;
         try {
-          serialized = JSON.stringify(nextAst);
+          serialized = JSON.stringify(nextAst, null, 2);
         } catch (e) {
           // Serialize error
           return callback(e);
@@ -56,3 +56,26 @@ export class SqliteParserTransform extends Transform {
     callback();
   }
 }
+
+export class SingleNodeTransform extends Transform {
+  constructor(options) {
+    super(options);
+    this.push(`{\n  "type": "statement",\n  "variant": "list",\n  "statement": [\n    `);
+    this.queries = 0;
+  }
+
+  _transform(data, encoding, callback) {
+    data = data.toString();
+    if (this.queries !== 0) {
+      data = `,\n${data}`;
+    }
+    this.queries += 1;
+    this.push(data.replace(/\n/g, '\n    '));
+    callback();
+  }
+
+  _flush(callback) {
+    this.push(`\n  ]\n}`);
+    callback();
+  }
+}