fix(engine): implement support for data-sly-unwrap

fixes #55 

Thanks @znikolovski

src/parser/html/MarkupHandler.js

@@ -38,6 +38,7 @@ const PLUGINS = {
   list: require('../plugins/ListPlugin'),
   repeat: require('../plugins/ListPlugin'),
   test: require('../plugins/TestPlugin'),
+  unwrap: require('../plugins/UnwrapPlugin'),
   attribute: require('../plugins/AttributePlugin'),
   use: require('../plugins/UsePlugin'),
   resource: require('../plugins/ResourcePlugin'),

src/parser/plugins/UnwrapPlugin.js

@@ -0,0 +1,64 @@
+/*
+ * Copyright 2018 Adobe. All rights reserved.
+ * This file is licensed to you 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 REPRESENTATIONS
+ * OF ANY KIND, either express or implied. See the License for the specific language
+ * governing permissions and limitations under the License.
+ */
+
+const Plugin = require('../html/Plugin');
+const VariableBinding = require('../commands/VariableBinding');
+const Conditional = require('../commands/Conditional');
+const BooleanConstant = require('../htl/nodes/BooleanConstant');
+const StringConstant = require('../htl/nodes/StringConstant');
+
+module.exports = class UnwrapPlugin extends Plugin {
+
+  beforeElement(stream/* , tagName */) {
+    const ctx = this.pluginContext;
+    this.variableName = this._signature.getVariableName(null);
+    this._useGlobalBinding = this.variableName != null;
+    if (this.variableName == null) {
+      this.variableName = ctx.generateVariable('unwrapCondition');
+    }
+
+    this.unwrapTest = new Conditional.Start(this.variableName, true);
+
+    if (this._useGlobalBinding) {
+      stream.write(new VariableBinding.Global(this.variableName, this.expression.root));
+    } else {
+      stream.write(new VariableBinding.Start(this.variableName, this.testRoot()));
+    }
+  }
+
+  beforeTagOpen(stream) {
+    stream.write(this.unwrapTest);
+  }
+
+  afterTagOpen(stream) {
+    stream.write(Conditional.END);
+  }
+
+  beforeTagClose(stream) {
+    stream.write(this.unwrapTest);
+  }
+
+  afterTagClose(stream) {
+    stream.write(Conditional.END);
+  }
+
+  afterElement(stream) {
+    if (!this._useGlobalBinding) {
+      stream.write(VariableBinding.END);
+    }
+  }
+
+  testRoot() {
+    let testNode = this.expression.root instanceof StringConstant && this.expression.root.text.length == 0;
+    return testNode ? BooleanConstant.TRUE : this.expression.root;
+  }
+};

test/specs/unwrap_spec.js

@@ -0,0 +1,18 @@
+/*
+ * Copyright 2018 Adobe. All rights reserved.
+ * This file is licensed to you 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 REPRESENTATIONS
+ * OF ANY KIND, either express or implied. See the License for the specific language
+ * governing permissions and limitations under the License.
+ */
+module.exports = {
+  properties: {
+    unwrap: true,
+    url: 'url',
+    title: 'yes'
+  },
+};

test/specs/unwrap_spec.txt

@@ -0,0 +1,28 @@
+#
+### unwrap with value and variable
+#
+<a href="${properties.url}" data-sly-unwrap.unwrapTest="${properties.unwrap}">
+    <span>${properties.title}</span>
+</a>
+===
+
+    <span>yes</span>
+
+#
+### unwrap with value no variable
+#
+<a href="${properties.url}" data-sly-unwrap="${properties.unwrap}">
+    <span>${properties.title}</span>
+</a>
+===
+
+    <span>yes</span>
+
+#
+### unwrap
+#
+<a href="${properties.url}" data-sly-unwrap><span>${properties.title}</span></a>
+===
+<span>yes</span>
+#
+###