Collapse Maven and Gradle setup into one section with switchable examples

This commit adds an Asciidoctor extension that post-processes code
blocks, collapsing any secondary blocks into the preceding primary
block. The primary block is then augmented with a switch. This switch
contains one item for each block. Clicking an item causes the associated
block’s content to be displayed. Each item is named using its block’s
title.

The getting started instructions have been updated to take advantage of
this new switching support, with the Maven and Gradle instructions
being collapsed into a single section.

Closes gh-189

buildSrc/src/main/groovy/org/springframework/restdocs/asciidoctor/CodeBlockSwitchExtension.groovy

@@ -0,0 +1,28 @@
+/*
+ * Copyright 2014-2016 the original author or authors.
+ *
+ * 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.
+ */
+
+package org.springframework.restdocs.asciidoctor
+
+import org.asciidoctor.Asciidoctor
+import org.asciidoctor.extension.spi.ExtensionRegistry
+
+class CodeBlockSwitchExtension implements ExtensionRegistry {
+
+	@Override
+	public void register(Asciidoctor asciidoctor) {
+		asciidoctor.javaExtensionRegistry().postprocessor(new CodeBlockSwitchPostProcessor());
+	}
+}

buildSrc/src/main/groovy/org/springframework/restdocs/asciidoctor/CodeBlockSwitchPostProcessor.groovy

@@ -0,0 +1,39 @@
+/*
+ * Copyright 2014-2015 the original author or authors.
+ *
+ * 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.
+ */
+
+package org.springframework.restdocs.asciidoctor
+
+import org.asciidoctor.ast.Document
+import org.asciidoctor.extension.Postprocessor
+
+class CodeBlockSwitchPostProcessor extends Postprocessor {
+
+	String process(Document document, String output) {
+		def css = getClass().getResource("/codeBlockSwitch.css").text
+		def javascript = getClass().getResource("/codeBlockSwitch.js").text
+		def replacement = """<style>
+$css
+</style>
+<script src=\"http://cdnjs.cloudflare.com/ajax/libs/zepto/1.1.6/zepto.min.js\"></script>
+<script type="text/javascript">
+$javascript
+</script>
+</head>
+"""
+		return output.replace("</head>", replacement);
+	}
+
+}

buildSrc/src/main/resources/META-INF/services/org.asciidoctor.extension.spi.ExtensionRegistry

@@ -0,0 +1 @@
+org.springframework.restdocs.asciidoctor.CodeBlockSwitchExtension

buildSrc/src/main/resources/codeBlockSwitch.css

@@ -0,0 +1,23 @@
+.hidden {
+	display: none;
+}
+
+.switch {
+	border-width: 1px 1px 0 1px;
+	border-style: solid;
+	border-color: #7a2518;
+	display: inline-block;
+}
+
+.switch--item {
+	padding: 10px;
+	background-color: #ffffff;
+	color: #7a2518;
+	display: inline-block;
+	cursor: pointer;
+}
+
+.switch--item.selected {
+	background-color: #7a2519;
+	color: #ffffff;
+}

buildSrc/src/main/resources/codeBlockSwitch.js

@@ -0,0 +1,45 @@
+function addBlockSwitches() {
+	$('.primary').each(function() {
+		primary = $(this);
+		createSwitchItem(primary, createBlockSwitch(primary)).item.addClass("selected");
+		primary.children('.title').remove();
+	});
+	$('.secondary').each(function(idx, node) {
+		secondary = $(node);
+		primary = findPrimary(secondary);
+		switchItem = createSwitchItem(secondary, primary.children('.switch'));
+		switchItem.content.addClass('hidden');
+		findPrimary(secondary).append(switchItem.content);
+		secondary.remove();
+	});
+}
+
+function createBlockSwitch(primary) {
+	blockSwitch = $('<div class="switch"></div>');
+	primary.prepend(blockSwitch);
+	return blockSwitch;
+}
+
+function findPrimary(secondary) {
+	candidate = secondary.prev();
+	while (!candidate.is('.primary')) {
+		candidate = candidate.prev();
+	}
+	return candidate;
+}
+
+function createSwitchItem(block, blockSwitch) {
+	blockName = block.children('.title').text();
+	content = block.children('.content').first().append(block.next('.colist'));
+	item = $('<div class="switch--item">' + blockName + '</div>');
+	item.on('click', '', content, function(e) {
+		$(this).addClass('selected');
+		$(this).siblings().removeClass('selected');
+		e.data.siblings('.content').addClass('hidden');
+		e.data.removeClass('hidden');
+	});
+	blockSwitch.append(item);
+	return {'item': item, 'content': content};
+}
+
+$(addBlockSwitches);