add support for a listener to capture parse events

jdrew1303 · Feb 10, 2016 · 3f9f8d4 · 3f9f8d4
1 parent fe94035
commit 3f9f8d4
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diff --git a/lib/js-yaml/loader.js b/lib/js-yaml/loader.js
@@ -132,6 +132,7 @@ function State(input, options) {
   this.onWarning = options['onWarning'] || null;
   this.legacy    = options['legacy']    || false;
   this.json      = options['json']      || false;
+  this.listener  = options['listener']  || null;
 
   this.implicitTypes = this.schema.compiledImplicit;
   this.typeMap       = this.schema.compiledTypeMap;
@@ -1266,6 +1267,10 @@ function composeNode(state, parentIndent, nodeContext, allowToSeek, allowCompact
       flowIndent,
       blockIndent;
 
+  if (state.listener !== null) {
+    state.listener('open', state);
+  }
+
   state.tag    = null;
   state.anchor = null;
   state.kind   = null;
@@ -1399,6 +1404,9 @@ function composeNode(state, parentIndent, nodeContext, allowToSeek, allowCompact
     }
   }
 
+  if (state.listener !== null) {
+    state.listener('close', state);
+  }
   return null !== state.tag || null !== state.anchor || hasContent;
 }
 

diff --git a/test/issues/0248-listener.js b/test/issues/0248-listener.js
@@ -0,0 +1,62 @@
+'use strict';
+
+var assert = require('assert');
+var yaml = require('../../');
+
+test('Listener informed on a very simple scalar.', function () {
+  var history = [];
+  function l(eventType, state) {
+    history.push([ eventType, state.position ]);
+  }
+
+  yaml.load('a_simple_scalar', { listener: l });
+
+  // 2 open events then 2 close events
+  assert.equal(history.length, 4);
+  assert.equal(history[0][0], 'open');
+  assert.equal(history[1][0], 'open');
+  assert.equal(history[2][0], 'close');
+  assert.equal(history[3][0], 'close');
+  assert.equal(history[0][1], 0);
+  assert.equal(history[3][1], 16);
+});
+
+test('Listener informed on a map with a list.', function () {
+  var history = [];
+  function l(eventType, state) {
+    history.push([ eventType, state.position, state.result ]);
+  }
+
+  yaml.load('{ a: 1, b: [ 0, xyz ] }', { listener: l });
+
+  var i = -1;
+  assert.equal(history[++i][0], 'open'); // doc
+  assert.equal(history[++i][0], 'open'); // map
+
+  assert.equal(history[++i][0], 'open'); // key
+  assert.equal(history[++i][0], 'close');
+  assert.equal(history[i][2], 'a');
+
+  assert.equal(history[++i][0], 'open'); // a value
+  assert.equal(history[++i][0], 'close');
+  assert.equal(history[i][2], 1);
+
+  assert.equal(history[++i][0], 'open'); // key
+  assert.equal(history[++i][0], 'close');
+  assert.equal(history[i][2], 'b');
+
+  assert.equal(history[++i][0], 'open'); // b value (list)
+  assert.equal(history[++i][0], 'open'); // item in list
+  assert.equal(history[++i][0], 'close');
+  assert.equal(history[i][2], 0);
+  assert.equal(history[++i][0], 'open'); // item in list
+  assert.equal(history[++i][0], 'close');
+
+  assert.equal(history[++i][0], 'close'); // b value (list) end
+  assert.deepEqual(history[i][2], [ 0, 'xyz' ]);
+
+  assert.equal(history[++i][0], 'close'); // map end
+  assert.equal(history[++i][0], 'close'); // doc end
+
+  assert.equal(history.length, ++i);
+});