Add PDF backend

Add a PDF backend that applies the same code chomping rules as
the HTML backend and also removed any `@fold` comments.

Closes gh-45

Author: philwebb

build.gradle

@@ -41,8 +41,11 @@ repositories {
 dependencies {
 	checkstyle("io.spring.javaformat:spring-javaformat-checkstyle:$springJavaFormatVersion")
 	compileOnly("org.asciidoctor:asciidoctorj:$asciidoctorjVersion")
+	compileOnly("org.asciidoctor:asciidoctorj-pdf:$asciidoctorjPdfVersion")
 	testImplementation("com.google.guava:guava:30.1-jre")
+	testImplementation("org.apache.pdfbox:pdfbox:2.0.23")
 	testImplementation("org.asciidoctor:asciidoctorj:$asciidoctorjVersion")
+	testImplementation("org.asciidoctor:asciidoctorj-pdf:$asciidoctorjPdfVersion")
 	testImplementation("org.assertj:assertj-core:3.11.1")
 	testImplementation("org.jsoup:jsoup:1.13.1")
 	testImplementation("org.junit.jupiter:junit-jupiter:5.6.0")

gradle.properties

@@ -4,4 +4,5 @@ org.gradle.caching=true
 org.gradle.parallel=true
 
 asciidoctorjVersion=2.4.1
+asciidoctorjPdfVersion=1.5.3
 springJavaFormatVersion=0.0.27

src/main/java/io/spring/asciidoctor/backend/codetools/FoldRemovalListingContentConverter.java

@@ -0,0 +1,54 @@
+/*
+ * Copyright 2021 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
+ *
+ *      https://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 io.spring.asciidoctor.backend.codetools;
+
+import org.asciidoctor.ast.Block;
+
+/**
+ * {@link ListingContentConverter} to remove {@code fold} tags.
+ *
+ * @author Phillip Webb
+ */
+class FoldRemovalListingContentConverter implements ListingContentConverter {
+
+	@Override
+	public String convert(Block listingBlock, String content) {
+		Options<FoldOption> options = Options.get(listingBlock, "fold", FoldOption.class, FoldOption.DEFAULTS);
+		String lang = (String) listingBlock.getAttribute("language");
+		if ("java".equals(lang) && options.has(FoldOption.TAGS)) {
+			return removeFoldTags(content);
+		}
+		return content;
+	}
+
+	private String removeFoldTags(String content) {
+		StringBuilder result = new StringBuilder();
+		String[] lines = content.split("\n\r?");
+		for (String line : lines) {
+			if (!isFoldLine(line)) {
+				result.append(line);
+				result.append("\n");
+			}
+		}
+		return result.toString();
+	}
+
+	private boolean isFoldLine(String line) {
+		return line.trim().startsWith("//") && line.contains("@fold:");
+	}
+
+}

src/main/java/io/spring/asciidoctor/backend/codetools/HtmlListingContentConverters.java

@@ -0,0 +1,51 @@
+/*
+ * Copyright 2021 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
+ *
+ *      https://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 io.spring.asciidoctor.backend.codetools;
+
+import java.util.ArrayList;
+import java.util.List;
+
+import org.jruby.RubyObject;
+
+/**
+ * Utility called by the Ruby code to apply modifications to HTML code listings.
+ *
+ * @author Phillip Webb
+ */
+public final class HtmlListingContentConverters {
+
+	private static final ListingContentConverters converters;
+	static {
+		List<ListingContentConverter> converterInstances = new ArrayList<>();
+		converterInstances.add(new ChompListingContentConverter());
+		converterInstances.add(new FoldListingContentConverter());
+		converters = new ListingContentConverters(converterInstances);
+	}
+
+	private HtmlListingContentConverters() {
+	}
+
+	/**
+	 * Convert the content of the given node before it is added to the HTML.
+	 * @param node the node to convert
+	 * @return the converted content
+	 */
+	public static RubyObject content(RubyObject node) {
+		return converters.content(node);
+	}
+
+}

src/main/java/io/spring/asciidoctor/backend/codetools/ListingContentConverter.java

@@ -19,7 +19,8 @@
 import org.asciidoctor.ast.Block;
 
 /**
- * Strategy interface used by {@link ListingContentConverters} to convert listing content.
+ * Strategy interface used by {@link HtmlListingContentConverters} to convert listing
+ * content.
  *
  * @author Phillip Webb
  */

src/main/java/io/spring/asciidoctor/backend/codetools/ListingContentConverters.java

@@ -16,7 +16,6 @@
 
 package io.spring.asciidoctor.backend.codetools;
 
-import java.util.ArrayList;
 import java.util.Collections;
 import java.util.List;
 
@@ -25,32 +24,22 @@
 import org.jruby.RubyObject;
 
 /**
- * Utility called by the Ruby code to apply modifications to code listings.
+ * A collection of {@link ListingContentConverter} instances.
  *
  * @author Phillip Webb
  */
-public final class ListingContentConverters {
-
-	private static final List<ListingContentConverter> converters;
-	static {
-		List<ListingContentConverter> converterInstances = new ArrayList<>();
-		converterInstances.add(new ChompListingContentConverter());
-		converterInstances.add(new FoldListingContentConverter());
-		converters = Collections.unmodifiableList(converterInstances);
-	}
+public class ListingContentConverters {
+
+	private final List<ListingContentConverter> converters;
 
-	private ListingContentConverters() {
+	ListingContentConverters(List<ListingContentConverter> converters) {
+		this.converters = Collections.unmodifiableList(converters);
 	}
 
-	/**
-	 * Convert the content of the given node before it is added to the HTML.
-	 * @param node the node to convert
-	 * @return the converted content
-	 */
-	public static RubyObject content(RubyObject node) {
+	RubyObject content(RubyObject node) {
 		Block listingBlock = (Block) NodeConverter.createASTNode(node);
 		String content = (String) listingBlock.getContent();
-		for (ListingContentConverter converter : converters) {
+		for (ListingContentConverter converter : this.converters) {
 			content = (content != null) ? content : "";
 			content = converter.convert(listingBlock, content);
 		}

src/main/java/io/spring/asciidoctor/backend/codetools/PdfListingContentConverters.java

@@ -0,0 +1,51 @@
+/*
+ * Copyright 2021 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
+ *
+ *      https://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 io.spring.asciidoctor.backend.codetools;
+
+import java.util.ArrayList;
+import java.util.List;
+
+import org.jruby.RubyObject;
+
+/**
+ * Utility called by the Ruby code to apply modifications to PDF code listings.
+ *
+ * @author Phillip Webb
+ */
+public final class PdfListingContentConverters {
+
+	private static final ListingContentConverters converters;
+	static {
+		List<ListingContentConverter> converterInstances = new ArrayList<>();
+		converterInstances.add(new ChompListingContentConverter());
+		converterInstances.add(new FoldRemovalListingContentConverter());
+		converters = new ListingContentConverters(converterInstances);
+	}
+
+	private PdfListingContentConverters() {
+	}
+
+	/**
+	 * Convert the content of the given node before it is added to the HTML.
+	 * @param node the node to convert
+	 * @return the converted content
+	 */
+	public static RubyObject content(RubyObject node) {
+		return converters.content(node);
+	}
+
+}

src/main/ruby/lib/spring-asciidoctor-backends.rb

@@ -17,3 +17,8 @@
 
 require_relative "spring-asciidoctor-backends/spring-docinfo-processor"
 require_relative "spring-asciidoctor-backends/spring-html5-converter"
+
+begin
+  require_relative "spring-asciidoctor-backends/spring-pdf-converter"
+rescue LoadError
+end

src/main/ruby/lib/spring-asciidoctor-backends/spring-html5-converter.rb

@@ -102,7 +102,7 @@ def convert_listing(node)
 
   def convert_listing_content(node)
     begin
-      return Java::IoSpringAsciidoctorBackendCodetools::ListingContentConverters.content node
+      return Java::IoSpringAsciidoctorBackendCodetools::HtmlListingContentConverters.content node
     rescue NameError
       return node.content
     end

src/main/ruby/lib/spring-asciidoctor-backends/spring-pdf-converter.rb

@@ -0,0 +1,64 @@
+#
+# Copyright 2021 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
+#
+#      https://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.
+
+# coding: utf-8
+
+require "asciidoctor-pdf"
+
+begin
+  require "java"
+rescue LoadError
+end
+
+class SpringPdfConverter < Asciidoctor::PDF::Converter
+
+  register_for "spring-pdf"
+
+  def convert_listing_or_literal node
+    if (node.style != 'source')
+      return super
+    end
+    add_dest_for_block node if node.id
+    source_string = guard_indentation convert_listing_content(node)
+    source_chunks = (XMLMarkupRx.match? source_string) ? (text_formatter.format source_string) : [text: source_string]
+    adjusted_font_size = ((node.option? 'autofit') || (node.document.attr? 'autofit-option')) ? (theme_font_size_autofit source_chunks, :code) : nil
+    theme_margin :block, :top
+    keep_together do |box_height = nil|
+      caption_height = node.title? ? (layout_caption node, category: :code) : 0
+      theme_font :code do
+        theme_fill_and_stroke_block :code, (box_height - caption_height), background_color: nil, split_from_top: false if box_height
+        pad_box @theme.code_padding do
+          typeset_formatted_text source_chunks, (calc_line_metrics @theme.code_line_height || @theme.base_line_height),
+              color: (@theme.code_font_color || @font_color),
+              size: adjusted_font_size
+        end
+      end
+    end
+    stroke_horizontal_rule @theme.caption_border_bottom_color if node.title? && @theme.caption_border_bottom_color
+    theme_margin :block, :bottom
+  end
+
+  def convert_listing_content(node)
+    begin
+      return Java::IoSpringAsciidoctorBackendCodetools::PdfListingContentConverters.content node
+    rescue NameError
+      return node.content
+    end
+  end
+
+
+  alias convert_listing convert_listing_or_literal
+
+end

src/test/gradle/build.gradle

@@ -1,5 +1,5 @@
 plugins {
-	id 'org.asciidoctor.jvm.convert' version '3.1.0'
+	id 'org.asciidoctor.jvm.convert' version '3.3.2'
 }
 
 repositories {
@@ -15,8 +15,10 @@ configurations {
 
 dependencies {
 	asciidoctorExtensions "io.spring.asciidoctor.backends:spring-asciidoctor-backends:" + System.getenv("spring-asciidoctor-backends.version")
+	asciidoctorExtensions "org.asciidoctor:asciidoctorj-pdf:1.5.3"
 }
 
+
 asciidoctor {
 	configurations "asciidoctorExtensions"
 	sourceDir "src/asciidoc"
@@ -25,3 +27,13 @@ asciidoctor {
 		backends "spring-html"
 	}
 }
+
+task asciidoctorPdf(type: org.asciidoctor.gradle.jvm.AsciidoctorTask) {
+	configurations "asciidoctorExtensions"
+	sourceDir "src/asciidoc"
+	baseDirFollowsSourceDir()
+	copyNoResources()
+	outputOptions {
+		backends "spring-pdf"
+	}
+}

src/test/java/io/spring/asciidoctor/backend/codetools/FoldRemovalListingContentConverterTests.java

@@ -0,0 +1,44 @@
+/*
+ * Copyright 2021 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
+ *
+ *      https://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 io.spring.asciidoctor.backend.codetools;
+
+import io.spring.asciidoctor.backend.testsupport.AsciidoctorExtension;
+import io.spring.asciidoctor.backend.testsupport.ConvertedPdf;
+import org.junit.jupiter.api.Test;
+import org.junit.jupiter.api.extension.ExtendWith;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+/**
+ * Tests for {@link FoldRemovalListingContentConverter}.
+ *
+ * @author Phillip Webb
+ */
+@ExtendWith(AsciidoctorExtension.class)
+class FoldRemovalListingContentConverterTests {
+
+	@Test
+	void convertWhenHasFoldCommentReturnsRemoved(ConvertedPdf pdf) {
+		assertThat(pdf.toString()).doesNotContain("@fold");
+	}
+
+	@Test
+	void convertWhenHasCodeFoldingDisabledAsDocumentAttributeReturnsUnchanged(ConvertedPdf pdf) {
+		assertThat(pdf.toString()).contains("@fold");
+	}
+
+}