467275: introduce a builder for ProcessingContext

Introduce a builder for ProcessingContext to make the possibility of
modifications explicit.

Change-Id: If627e8001487ea97cade0d178176db6a1ec03256
Task-Url: https://bugs.eclipse.org/bugs/show_bug.cgi?id=467275

15 files changed, 132 insertions, 112 deletions

diff --git a/org.eclipse.mylyn.wikitext.commonmark.tests/src/org/eclipse/mylyn/internal/wikitext/commonmark/ProcessingContextTest.java b/org.eclipse.mylyn.wikitext.commonmark.tests/src/org/eclipse/mylyn/internal/wikitext/commonmark/ProcessingContextTest.java
index d69b0b858..2bfd62877 100644
--- a/org.eclipse.mylyn.wikitext.commonmark.tests/src/org/eclipse/mylyn/internal/wikitext/commonmark/ProcessingContextTest.java
+++ b/org.eclipse.mylyn.wikitext.commonmark.tests/src/org/eclipse/mylyn/internal/wikitext/commonmark/ProcessingContextTest.java
@@ -14,27 +14,29 @@ package org.eclipse.mylyn.internal.wikitext.commonmark;
 import static org.junit.Assert.assertEquals;
 import static org.junit.Assert.assertFalse;
 import static org.junit.Assert.assertNotNull;
-import static org.junit.Assert.assertNotSame;
 import static org.junit.Assert.assertNull;
-import static org.junit.Assert.assertSame;
 import static org.junit.Assert.assertTrue;
 
 import org.eclipse.mylyn.internal.wikitext.commonmark.ProcessingContext.NamedUriWithTitle;
+import org.junit.Rule;
 import org.junit.Test;
+import org.junit.rules.ExpectedException;
 
 public class ProcessingContextTest {
 
+	@Rule
+	public final ExpectedException thrown = ExpectedException.none();
+
 	@Test
 	public void empty() {
 		ProcessingContext context = ProcessingContext.empty();
 		assertNotNull(context);
 		assertTrue(context.isEmpty());
-		assertSame(context, ProcessingContext.empty());
 	}
 
 	@Test
-	public void withReferenceDefinition() {
-		ProcessingContext context = ProcessingContext.withReferenceDefinition("onE", "/uri", "a title");
+	public void referenceDefinition() {
+		ProcessingContext context = ProcessingContext.builder().referenceDefinition("onE", "/uri", "a title").build();
 		assertNotNull(context);
 		assertFalse(context.isEmpty());
 		assertNotNull(context.namedUriWithTitle("one"));
@@ -44,30 +46,22 @@ public class ProcessingContextTest {
 		assertEquals("/uri", link.getUri());
 		assertEquals("a title", link.getTitle());
 		assertNull(context.namedUriWithTitle("Unknown"));
-		assertSame(ProcessingContext.empty(), ProcessingContext.withReferenceDefinition("", "one", "two"));
+
 	}
 
 	@Test
-	public void merge() {
-		ProcessingContext empty1 = ProcessingContext.empty();
-		ProcessingContext empty2 = ProcessingContext.empty();
-		assertSame(empty1, empty1.merge(empty2));
-		ProcessingContext other = ProcessingContext.withReferenceDefinition("one", "/uri", "a title");
-		assertSame(other, other.merge(empty1));
-		assertSame(other, empty1.merge(other));
-		ProcessingContext other2 = ProcessingContext.withReferenceDefinition("two", "/uri2", "a title");
-		ProcessingContext merged = other.merge(other2);
-		assertNotSame(other2, merged);
-		assertNotSame(other, merged);
-		assertNotNull(merged.namedUriWithTitle("two"));
-		assertNotNull(merged.namedUriWithTitle("one"));
+	public void referenceDefinitionEmptyName() {
+		assertTrue(ProcessingContext.builder().referenceDefinition("", "one", "two").build().isEmpty());
 	}
 
 	@Test
-	public void precedence() {
-		ProcessingContext one = ProcessingContext.withReferenceDefinition("one", "1", "a title");
-		ProcessingContext one2 = ProcessingContext.withReferenceDefinition("one", "2", "a title");
-		ProcessingContext merged = one.merge(one2);
-		assertEquals("1", merged.namedUriWithTitle("one").getUri());
+	public void referenceDefinitionDuplicate() {
+		ProcessingContext context = ProcessingContext.builder()
+				.referenceDefinition("a", "/uri", "a title")
+				.referenceDefinition("a", "/uri2", "a title2")
+				.build();
+		NamedUriWithTitle uriWithTitle = context.namedUriWithTitle("a");
+		assertEquals("/uri", uriWithTitle.getUri());
 	}
+
 }
diff --git a/org.eclipse.mylyn.wikitext.commonmark.tests/src/org/eclipse/mylyn/internal/wikitext/commonmark/inlines/InlineTest.java b/org.eclipse.mylyn.wikitext.commonmark.tests/src/org/eclipse/mylyn/internal/wikitext/commonmark/inlines/InlineTest.java
index 19e3350f4..9294c0c1e 100644
--- a/org.eclipse.mylyn.wikitext.commonmark.tests/src/org/eclipse/mylyn/internal/wikitext/commonmark/inlines/InlineTest.java
+++ b/org.eclipse.mylyn.wikitext.commonmark.tests/src/org/eclipse/mylyn/internal/wikitext/commonmark/inlines/InlineTest.java
@@ -13,9 +13,11 @@ package org.eclipse.mylyn.internal.wikitext.commonmark.inlines;
 
 import static org.junit.Assert.assertEquals;
 import static org.junit.Assert.assertSame;
+import static org.junit.Assert.assertTrue;
 
 import org.eclipse.mylyn.internal.wikitext.commonmark.Line;
 import org.eclipse.mylyn.internal.wikitext.commonmark.ProcessingContext;
+import org.eclipse.mylyn.internal.wikitext.commonmark.ProcessingContextBuilder;
 import org.eclipse.mylyn.wikitext.core.parser.DocumentBuilder;
 import org.eclipse.mylyn.wikitext.core.parser.Locator;
 import org.junit.Test;
@@ -45,12 +47,14 @@ public class InlineTest {
 
 	@Test
 	public void createContext() {
-		ProcessingContext context = new Inline(new Line(1, 2, "text"), 0, 1) {
+		ProcessingContextBuilder builder = ProcessingContext.builder();
+		new Inline(new Line(1, 2, "text"), 0, 1) {
 
 			@Override
 			public void emit(DocumentBuilder builder) {
 			}
-		}.createContext();
-		assertSame(ProcessingContext.empty(), context);
+		}.createContext(builder);
+		ProcessingContext context = builder.build();
+		assertTrue(context.isEmpty());
 	}
 }
diff --git a/org.eclipse.mylyn.wikitext.commonmark/src/org/eclipse/mylyn/internal/wikitext/commonmark/ProcessingContext.java b/org.eclipse.mylyn.wikitext.commonmark/src/org/eclipse/mylyn/internal/wikitext/commonmark/ProcessingContext.java
index 3e161bd82..5b36aa14c 100644
--- a/org.eclipse.mylyn.wikitext.commonmark/src/org/eclipse/mylyn/internal/wikitext/commonmark/ProcessingContext.java
+++ b/org.eclipse.mylyn.wikitext.commonmark/src/org/eclipse/mylyn/internal/wikitext/commonmark/ProcessingContext.java
@@ -13,16 +13,17 @@ package org.eclipse.mylyn.internal.wikitext.commonmark;
 
 import static com.google.common.base.Preconditions.checkNotNull;
 
-import java.util.HashMap;
-import java.util.Locale;
-import java.util.Map;
-
-import com.google.common.base.Strings;
 import com.google.common.collect.ImmutableMap;
 
 public class ProcessingContext {
 
-	private static final ProcessingContext EMPTY_CONTEXT = new ProcessingContext();
+	public static ProcessingContextBuilder builder() {
+		return new ProcessingContextBuilder();
+	}
+
+	public static ProcessingContext empty() {
+		return builder().build();
+	}
 
 	public static class NamedUriWithTitle {
 
@@ -53,45 +54,15 @@ public class ProcessingContext {
 
 	private final ImmutableMap<String, NamedUriWithTitle> links;
 
-	private ProcessingContext(ImmutableMap<String, NamedUriWithTitle> links) {
+	ProcessingContext(ImmutableMap<String, NamedUriWithTitle> links) {
 		this.links = checkNotNull(links);
 	}
 
-	public ProcessingContext() {
-		this(ImmutableMap.<String, NamedUriWithTitle> of());
-	}
-
-	public static ProcessingContext empty() {
-		return EMPTY_CONTEXT;
-	}
-
-	public static ProcessingContext withReferenceDefinition(String name, String href, String title) {
-		if (Strings.isNullOrEmpty(name)) {
-			return empty();
-		}
-		return new ProcessingContext(ImmutableMap.of(name.toLowerCase(Locale.ROOT), new NamedUriWithTitle(name, href,
-				title)));
-	}
-
 	public boolean isEmpty() {
 		return links.isEmpty();
 	}
 
-	public ProcessingContext merge(ProcessingContext other) {
-		checkNotNull(other);
-		if (other.isEmpty()) {
-			return this;
-		} else if (isEmpty()) {
-			return other;
-		}
-		Map<String, NamedUriWithTitle> mergedLinks = new HashMap<>();
-		mergedLinks.putAll(other.links);
-		mergedLinks.putAll(links);
-		return new ProcessingContext(ImmutableMap.copyOf(mergedLinks));
-	}
-
 	public NamedUriWithTitle namedUriWithTitle(String name) {
 		return links.get(name.toLowerCase());
 	}
-
 }
diff --git a/org.eclipse.mylyn.wikitext.commonmark/src/org/eclipse/mylyn/internal/wikitext/commonmark/ProcessingContextBuilder.java b/org.eclipse.mylyn.wikitext.commonmark/src/org/eclipse/mylyn/internal/wikitext/commonmark/ProcessingContextBuilder.java
new file mode 100644
index 000000000..8cd11de47
--- /dev/null
+++ b/org.eclipse.mylyn.wikitext.commonmark/src/org/eclipse/mylyn/internal/wikitext/commonmark/ProcessingContextBuilder.java
@@ -0,0 +1,44 @@
+/*******************************************************************************
+ * Copyright (c) 2015 David Green.
+ * All rights reserved. This program and the accompanying materials
+ * are made available under the terms of the Eclipse Public License v1.0
+ * which accompanies this distribution, and is available at
+ * http://www.eclipse.org/legal/epl-v10.html
+ *
+ * Contributors:
+ *     David Green - initial API and implementation
+ *******************************************************************************/
+
+package org.eclipse.mylyn.internal.wikitext.commonmark;
+
+import java.util.HashMap;
+import java.util.Locale;
+import java.util.Map;
+
+import org.eclipse.mylyn.internal.wikitext.commonmark.ProcessingContext.NamedUriWithTitle;
+
+import com.google.common.base.Strings;
+import com.google.common.collect.ImmutableMap;
+
+public class ProcessingContextBuilder {
+
+	private final Map<String, NamedUriWithTitle> linkByName = new HashMap<>();
+
+	public ProcessingContextBuilder referenceDefinition(String name, String href, String title) {
+		if (!Strings.isNullOrEmpty(name)) {
+			String key = name.toLowerCase(Locale.ROOT);
+			if (!linkByName.containsKey(key)) {
+				linkByName.put(key, new NamedUriWithTitle(name, href, title));
+			}
+		}
+		return this;
+	}
+
+	public ProcessingContext build() {
+		return new ProcessingContext(ImmutableMap.copyOf(linkByName));
+	}
+
+	ProcessingContextBuilder() {
+		// prevent instantiation
+	}
+}
diff --git a/org.eclipse.mylyn.wikitext.commonmark/src/org/eclipse/mylyn/internal/wikitext/commonmark/SourceBlock.java b/org.eclipse.mylyn.wikitext.commonmark/src/org/eclipse/mylyn/internal/wikitext/commonmark/SourceBlock.java
index 753e67c0d..a0df18e33 100644
--- a/org.eclipse.mylyn.wikitext.commonmark/src/org/eclipse/mylyn/internal/wikitext/commonmark/SourceBlock.java
+++ b/org.eclipse.mylyn.wikitext.commonmark/src/org/eclipse/mylyn/internal/wikitext/commonmark/SourceBlock.java
@@ -19,9 +19,7 @@ public abstract class SourceBlock {
 
 	public abstract boolean canStart(LineSequence lineSequence);
 
-	public ProcessingContext createContext(LineSequence lineSequence) {
-		ProcessingContext context = ProcessingContext.empty();
-		process(context, new NoOpDocumentBuilder(), lineSequence);
-		return context;
+	public void createContext(ProcessingContextBuilder contextBuilder, LineSequence lineSequence) {
+		process(contextBuilder.build(), new NoOpDocumentBuilder(), lineSequence);
 	}
 }
diff --git a/org.eclipse.mylyn.wikitext.commonmark/src/org/eclipse/mylyn/internal/wikitext/commonmark/SourceBlocks.java b/org.eclipse.mylyn.wikitext.commonmark/src/org/eclipse/mylyn/internal/wikitext/commonmark/SourceBlocks.java
index 772f32bdc..2958433fa 100644
--- a/org.eclipse.mylyn.wikitext.commonmark/src/org/eclipse/mylyn/internal/wikitext/commonmark/SourceBlocks.java
+++ b/org.eclipse.mylyn.wikitext.commonmark/src/org/eclipse/mylyn/internal/wikitext/commonmark/SourceBlocks.java
@@ -16,7 +16,6 @@ import static com.google.common.base.Preconditions.checkNotNull;
 import java.util.ArrayList;
 import java.util.Arrays;
 import java.util.List;
-import java.util.concurrent.atomic.AtomicReference;
 
 import org.eclipse.mylyn.wikitext.core.parser.DocumentBuilder;
 import org.eclipse.mylyn.wikitext.core.parser.builder.NoOpDocumentBuilder;
@@ -69,22 +68,20 @@ public class SourceBlocks extends SourceBlock {
 		void run(LineSequence lineSequence, SourceBlock sourceBlock);
 	}
 
-	public ProcessingContext createContext(LineSequence lineSequence, Predicate<BlockContext> contextPredicate) {
-		final AtomicReference<ProcessingContext> context = new AtomicReference<ProcessingContext>(
-				ProcessingContext.empty());
+	public void createContext(final ProcessingContextBuilder contextBuilder, LineSequence lineSequence,
+			Predicate<BlockContext> contextPredicate) {
 		process(lineSequence, new SourceBlockRunnable() {
 
 			@Override
 			public void run(LineSequence lineSequence, SourceBlock sourceBlock) {
-				context.set(checkNotNull(context.get()).merge(sourceBlock.createContext(lineSequence)));
+				sourceBlock.createContext(contextBuilder, lineSequence);
 			}
 		}, contextPredicate);
-		return checkNotNull(context.get());
 	}
 
 	@Override
-	public ProcessingContext createContext(LineSequence lineSequence) {
-		return createContext(lineSequence, Predicates.<BlockContext> alwaysTrue());
+	public void createContext(ProcessingContextBuilder contextBuilder, LineSequence lineSequence) {
+		createContext(contextBuilder, lineSequence, Predicates.<BlockContext> alwaysTrue());
 	}
 
 	@Override
diff --git a/org.eclipse.mylyn.wikitext.commonmark/src/org/eclipse/mylyn/internal/wikitext/commonmark/blocks/BlockQuoteBlock.java b/org.eclipse.mylyn.wikitext.commonmark/src/org/eclipse/mylyn/internal/wikitext/commonmark/blocks/BlockQuoteBlock.java
index 4b5036002..bcd5069d8 100644
--- a/org.eclipse.mylyn.wikitext.commonmark/src/org/eclipse/mylyn/internal/wikitext/commonmark/blocks/BlockQuoteBlock.java
+++ b/org.eclipse.mylyn.wikitext.commonmark/src/org/eclipse/mylyn/internal/wikitext/commonmark/blocks/BlockQuoteBlock.java
@@ -22,6 +22,7 @@ import org.eclipse.mylyn.internal.wikitext.commonmark.CommonMark;
 import org.eclipse.mylyn.internal.wikitext.commonmark.Line;
 import org.eclipse.mylyn.internal.wikitext.commonmark.LineSequence;
 import org.eclipse.mylyn.internal.wikitext.commonmark.ProcessingContext;
+import org.eclipse.mylyn.internal.wikitext.commonmark.ProcessingContextBuilder;
 import org.eclipse.mylyn.internal.wikitext.commonmark.SourceBlock;
 import org.eclipse.mylyn.internal.wikitext.commonmark.SourceBlocks;
 import org.eclipse.mylyn.internal.wikitext.commonmark.SourceBlocks.BlockContext;
@@ -50,10 +51,10 @@ public class BlockQuoteBlock extends BlockWithNestedBlocks {
 	}
 
 	@Override
-	public ProcessingContext createContext(LineSequence lineSequence) {
+	public void createContext(ProcessingContextBuilder contextBuilder, LineSequence lineSequence) {
 		SourceBlocks sourceBlocks = CommonMark.sourceBlocks();
 		BlockQuoteState blockQuoteState = new BlockQuoteState();
-		return sourceBlocks.createContext(blockQuoteState.blockQuoteLineSequence(lineSequence),
+		sourceBlocks.createContext(contextBuilder, blockQuoteState.blockQuoteLineSequence(lineSequence),
 				blockQuoteState.contextPredicate());
 	}
 
@@ -107,7 +108,8 @@ public class BlockQuoteBlock extends BlockWithNestedBlocks {
 				}
 
 				private boolean isLazyContinuation(SourceBlock lineBlock) {
-					return lineBlock instanceof ParagraphBlock && (currentBlock instanceof BlockQuoteBlock || currentBlock instanceof ParagraphBlock);
+					return lineBlock instanceof ParagraphBlock
+							&& (currentBlock instanceof BlockQuoteBlock || currentBlock instanceof ParagraphBlock);
 				}
 
 				private LineSequence createLookAhead(LineSequence lineSequence, Line line) {
diff --git a/org.eclipse.mylyn.wikitext.commonmark/src/org/eclipse/mylyn/internal/wikitext/commonmark/blocks/BlockWithNestedBlocks.java b/org.eclipse.mylyn.wikitext.commonmark/src/org/eclipse/mylyn/internal/wikitext/commonmark/blocks/BlockWithNestedBlocks.java
index 66386890c..e40035af2 100644
--- a/org.eclipse.mylyn.wikitext.commonmark/src/org/eclipse/mylyn/internal/wikitext/commonmark/blocks/BlockWithNestedBlocks.java
+++ b/org.eclipse.mylyn.wikitext.commonmark/src/org/eclipse/mylyn/internal/wikitext/commonmark/blocks/BlockWithNestedBlocks.java
@@ -12,11 +12,11 @@
 package org.eclipse.mylyn.internal.wikitext.commonmark.blocks;
 
 import org.eclipse.mylyn.internal.wikitext.commonmark.LineSequence;
-import org.eclipse.mylyn.internal.wikitext.commonmark.ProcessingContext;
+import org.eclipse.mylyn.internal.wikitext.commonmark.ProcessingContextBuilder;
 import org.eclipse.mylyn.internal.wikitext.commonmark.SourceBlock;
 
 abstract class BlockWithNestedBlocks extends SourceBlock {
 
 	@Override
-	public abstract ProcessingContext createContext(LineSequence lineSequence);
+	public abstract void createContext(ProcessingContextBuilder contextBuilder, LineSequence lineSequence);
 }
diff --git a/org.eclipse.mylyn.wikitext.commonmark/src/org/eclipse/mylyn/internal/wikitext/commonmark/blocks/ListBlock.java b/org.eclipse.mylyn.wikitext.commonmark/src/org/eclipse/mylyn/internal/wikitext/commonmark/blocks/ListBlock.java
index 7024dc818..23e481477 100644
--- a/org.eclipse.mylyn.wikitext.commonmark/src/org/eclipse/mylyn/internal/wikitext/commonmark/blocks/ListBlock.java
+++ b/org.eclipse.mylyn.wikitext.commonmark/src/org/eclipse/mylyn/internal/wikitext/commonmark/blocks/ListBlock.java
@@ -14,7 +14,6 @@ package org.eclipse.mylyn.internal.wikitext.commonmark.blocks;
 import static com.google.common.base.Preconditions.checkState;
 
 import java.util.List;
-import java.util.concurrent.atomic.AtomicReference;
 import java.util.regex.Matcher;
 import java.util.regex.Pattern;
 
@@ -22,6 +21,7 @@ import org.eclipse.mylyn.internal.wikitext.commonmark.CommonMark;
 import org.eclipse.mylyn.internal.wikitext.commonmark.Line;
 import org.eclipse.mylyn.internal.wikitext.commonmark.LineSequence;
 import org.eclipse.mylyn.internal.wikitext.commonmark.ProcessingContext;
+import org.eclipse.mylyn.internal.wikitext.commonmark.ProcessingContextBuilder;
 import org.eclipse.mylyn.internal.wikitext.commonmark.SourceBlock;
 import org.eclipse.mylyn.internal.wikitext.commonmark.SourceBlocks;
 import org.eclipse.mylyn.internal.wikitext.commonmark.SourceBlocks.BlockContext;
@@ -37,7 +37,8 @@ import com.google.common.base.Predicate;
 
 public class ListBlock extends BlockWithNestedBlocks {
 
-	private final Pattern bulletPattern = Pattern.compile("\\s{0,3}(([*+-])|(([0-9]{0,5})[.)]))(?:(?:\\s(\\s*)(.*))|\\s*$)");
+	private final Pattern bulletPattern = Pattern
+			.compile("\\s{0,3}(([*+-])|(([0-9]{0,5})[.)]))(?:(?:\\s(\\s*)(.*))|\\s*$)");
 
 	private final HorizontalRuleBlock horizontalRuleBlock = new HorizontalRuleBlock();
 
@@ -64,19 +65,16 @@ public class ListBlock extends BlockWithNestedBlocks {
 	}
 
 	@Override
-	public ProcessingContext createContext(LineSequence lineSequence) {
-		final AtomicReference<ProcessingContext> context = new AtomicReference<>(ProcessingContext.empty());
-		process(ProcessingContext.empty(), new NoOpDocumentBuilder(), lineSequence, new ListItemHandler() {
-
-			@Override
-			public void emitListItem(ProcessingContext dummyContext, DocumentBuilder builder, ListMode listMode,
-					LineSequence lineSequence) {
-				ProcessingContext itemContext = CommonMark.sourceBlocks().createContext(
-						listItemLineSequence(lineSequence));
-				context.set(context.get().merge(itemContext));
-			}
-		});
-		return context.get();
+	public void createContext(final ProcessingContextBuilder contextBuilder, LineSequence lineSequence) {
+		process(ProcessingContext.builder().build(), new NoOpDocumentBuilder(), lineSequence,
+				new ListItemHandler() {
+
+					@Override
+					public void emitListItem(ProcessingContext dummyContext, DocumentBuilder builder, ListMode listMode,
+							LineSequence lineSequence) {
+						CommonMark.sourceBlocks().createContext(contextBuilder, listItemLineSequence(lineSequence));
+					}
+				});
 	}
 
 	private void process(ProcessingContext context, DocumentBuilder builder, LineSequence lineSequence,
diff --git a/org.eclipse.mylyn.wikitext.commonmark/src/org/eclipse/mylyn/internal/wikitext/commonmark/blocks/ParagraphBlock.java b/org.eclipse.mylyn.wikitext.commonmark/src/org/eclipse/mylyn/internal/wikitext/commonmark/blocks/ParagraphBlock.java
index 1932ceffa..15e6ccac5 100644
--- a/org.eclipse.mylyn.wikitext.commonmark/src/org/eclipse/mylyn/internal/wikitext/commonmark/blocks/ParagraphBlock.java
+++ b/org.eclipse.mylyn.wikitext.commonmark/src/org/eclipse/mylyn/internal/wikitext/commonmark/blocks/ParagraphBlock.java
@@ -22,6 +22,7 @@ import org.eclipse.mylyn.internal.wikitext.commonmark.Line;
 import org.eclipse.mylyn.internal.wikitext.commonmark.LinePredicates;
 import org.eclipse.mylyn.internal.wikitext.commonmark.LineSequence;
 import org.eclipse.mylyn.internal.wikitext.commonmark.ProcessingContext;
+import org.eclipse.mylyn.internal.wikitext.commonmark.ProcessingContextBuilder;
 import org.eclipse.mylyn.internal.wikitext.commonmark.SourceBlock;
 import org.eclipse.mylyn.internal.wikitext.commonmark.TextSegment;
 import org.eclipse.mylyn.internal.wikitext.commonmark.inlines.Inline;
@@ -39,9 +40,9 @@ public class ParagraphBlock extends SourceBlock {
 			SetextHeaderBlock.class);
 
 	@Override
-	public ProcessingContext createContext(LineSequence lineSequence) {
+	public void createContext(ProcessingContextBuilder contextBuilder, LineSequence lineSequence) {
 		TextSegment textSegment = extractTextSegment(lineSequence);
-		return new InlineContent().createContext(textSegment);
+		new InlineContent().createContext(contextBuilder, textSegment);
 	}
 
 	@Override
@@ -49,7 +50,8 @@ public class ParagraphBlock extends SourceBlock {
 		processInlines(context, builder, lineSequence, true);
 	}
 
-	void processInlines(ProcessingContext context, DocumentBuilder builder, LineSequence lineSequence, boolean asBlock) {
+	void processInlines(ProcessingContext context, DocumentBuilder builder, LineSequence lineSequence,
+			boolean asBlock) {
 		TextSegment textSegment = extractTextSegment(lineSequence);
 		List<Inline> inlines = new InlineContent().parse(context, textSegment);
 		if (!emptyParagraph(inlines)) {
@@ -75,7 +77,8 @@ public class ParagraphBlock extends SourceBlock {
 
 	private TextSegment extractTextSegment(LineSequence lineSequence) {
 		List<Line> lines = new ArrayList<Line>();
-		while (lineSequence.getCurrentLine() != null && notEmptyLine(lineSequence) && !anotherBlockStart(lineSequence)) {
+		while (lineSequence.getCurrentLine() != null && notEmptyLine(lineSequence)
+				&& !anotherBlockStart(lineSequence)) {
 			lines.add(lineSequence.getCurrentLine());
 			lineSequence.advance();
 		}
diff --git a/org.eclipse.mylyn.wikitext.commonmark/src/org/eclipse/mylyn/internal/wikitext/commonmark/blocks/SetextHeaderBlock.java b/org.eclipse.mylyn.wikitext.commonmark/src/org/eclipse/mylyn/internal/wikitext/commonmark/blocks/SetextHeaderBlock.java
index 9ab6c9017..9d1449e1b 100644
--- a/org.eclipse.mylyn.wikitext.commonmark/src/org/eclipse/mylyn/internal/wikitext/commonmark/blocks/SetextHeaderBlock.java
+++ b/org.eclipse.mylyn.wikitext.commonmark/src/org/eclipse/mylyn/internal/wikitext/commonmark/blocks/SetextHeaderBlock.java
@@ -41,7 +41,8 @@ public class SetextHeaderBlock extends SourceBlock {
 		lineSequence.advance();
 
 		builder.setLocator(currentLine.toLocator());
-		builder.beginHeading(headingLevel(matcher), new HeadingAttributes());
+		int headingLevel = headingLevel(matcher);
+		builder.beginHeading(headingLevel, new HeadingAttributes());
 
 		new InlineContent().emit(context, builder, new TextSegment(Collections.singletonList(currentLine)));
 
diff --git a/org.eclipse.mylyn.wikitext.commonmark/src/org/eclipse/mylyn/internal/wikitext/commonmark/inlines/Inline.java b/org.eclipse.mylyn.wikitext.commonmark/src/org/eclipse/mylyn/internal/wikitext/commonmark/inlines/Inline.java
index b41ed77b8..9ced30004 100644
--- a/org.eclipse.mylyn.wikitext.commonmark/src/org/eclipse/mylyn/internal/wikitext/commonmark/inlines/Inline.java
+++ b/org.eclipse.mylyn.wikitext.commonmark/src/org/eclipse/mylyn/internal/wikitext/commonmark/inlines/Inline.java
@@ -19,6 +19,7 @@ import java.util.Objects;
 
 import org.eclipse.mylyn.internal.wikitext.commonmark.Line;
 import org.eclipse.mylyn.internal.wikitext.commonmark.ProcessingContext;
+import org.eclipse.mylyn.internal.wikitext.commonmark.ProcessingContextBuilder;
 import org.eclipse.mylyn.internal.wikitext.commonmark.SimpleLocator;
 import org.eclipse.mylyn.wikitext.core.parser.DocumentBuilder;
 import org.eclipse.mylyn.wikitext.core.parser.Locator;
@@ -69,8 +70,8 @@ public abstract class Inline {
 		return Optional.absent();
 	}
 
-	public ProcessingContext createContext() {
-		return ProcessingContext.empty();
+	public void createContext(ProcessingContextBuilder contextBuilder) {
+		// nothing to do
 	}
 
 	@Override
diff --git a/org.eclipse.mylyn.wikitext.commonmark/src/org/eclipse/mylyn/internal/wikitext/commonmark/inlines/InlineParser.java b/org.eclipse.mylyn.wikitext.commonmark/src/org/eclipse/mylyn/internal/wikitext/commonmark/inlines/InlineParser.java
index 28c8d4859..ef119702c 100644
--- a/org.eclipse.mylyn.wikitext.commonmark/src/org/eclipse/mylyn/internal/wikitext/commonmark/inlines/InlineParser.java
+++ b/org.eclipse.mylyn.wikitext.commonmark/src/org/eclipse/mylyn/internal/wikitext/commonmark/inlines/InlineParser.java
@@ -16,6 +16,7 @@ import java.util.Arrays;
 import java.util.List;
 
 import org.eclipse.mylyn.internal.wikitext.commonmark.ProcessingContext;
+import org.eclipse.mylyn.internal.wikitext.commonmark.ProcessingContextBuilder;
 import org.eclipse.mylyn.internal.wikitext.commonmark.TextSegment;
 import org.eclipse.mylyn.wikitext.core.parser.DocumentBuilder;
 import org.eclipse.mylyn.wikitext.core.parser.builder.NoOpDocumentBuilder;
@@ -47,12 +48,10 @@ public class InlineParser {
 		}
 	}
 
-	public ProcessingContext createContext(TextSegment textSegment) {
-		ProcessingContext context = ProcessingContext.empty();
-		for (Inline inline : parse(context, textSegment)) {
-			context = context.merge(inline.createContext());
+	public void createContext(ProcessingContextBuilder contextBuilder, TextSegment textSegment) {
+		for (Inline inline : parse(contextBuilder.build(), textSegment)) {
+			inline.createContext(contextBuilder);
 		}
-		return context;
 	}
 
 	public List<Inline> parse(ProcessingContext context, TextSegment segment) {
diff --git a/org.eclipse.mylyn.wikitext.commonmark/src/org/eclipse/mylyn/internal/wikitext/commonmark/inlines/ReferenceDefinition.java b/org.eclipse.mylyn.wikitext.commonmark/src/org/eclipse/mylyn/internal/wikitext/commonmark/inlines/ReferenceDefinition.java
index 3a0d3bef2..237609e63 100644
--- a/org.eclipse.mylyn.wikitext.commonmark/src/org/eclipse/mylyn/internal/wikitext/commonmark/inlines/ReferenceDefinition.java
+++ b/org.eclipse.mylyn.wikitext.commonmark/src/org/eclipse/mylyn/internal/wikitext/commonmark/inlines/ReferenceDefinition.java
@@ -16,7 +16,7 @@ import static com.google.common.base.Preconditions.checkNotNull;
 import java.util.Objects;
 
 import org.eclipse.mylyn.internal.wikitext.commonmark.Line;
-import org.eclipse.mylyn.internal.wikitext.commonmark.ProcessingContext;
+import org.eclipse.mylyn.internal.wikitext.commonmark.ProcessingContextBuilder;
 import org.eclipse.mylyn.internal.wikitext.commonmark.ToStringHelper;
 import org.eclipse.mylyn.wikitext.core.parser.DocumentBuilder;
 
@@ -45,8 +45,8 @@ public class ReferenceDefinition extends Inline {
 	}
 
 	@Override
-	public ProcessingContext createContext() {
-		return ProcessingContext.withReferenceDefinition(name, href, title);
+	public void createContext(ProcessingContextBuilder contextBuilder) {
+		contextBuilder.referenceDefinition(name, href, title);
 	}
 
 	@Override
diff --git a/org.eclipse.mylyn.wikitext.commonmark/src/org/eclipse/mylyn/wikitext/commonmark/CommonMarkLanguage.java b/org.eclipse.mylyn.wikitext.commonmark/src/org/eclipse/mylyn/wikitext/commonmark/CommonMarkLanguage.java
index 9b6cd566e..3f39c6de8 100644
--- a/org.eclipse.mylyn.wikitext.commonmark/src/org/eclipse/mylyn/wikitext/commonmark/CommonMarkLanguage.java
+++ b/org.eclipse.mylyn.wikitext.commonmark/src/org/eclipse/mylyn/wikitext/commonmark/CommonMarkLanguage.java
@@ -15,6 +15,7 @@ import static com.google.common.base.Preconditions.checkNotNull;
 import org.eclipse.mylyn.internal.wikitext.commonmark.CommonMark;
 import org.eclipse.mylyn.internal.wikitext.commonmark.LineSequence;
 import org.eclipse.mylyn.internal.wikitext.commonmark.ProcessingContext;
+import org.eclipse.mylyn.internal.wikitext.commonmark.ProcessingContextBuilder;
 import org.eclipse.mylyn.internal.wikitext.commonmark.SourceBlocks;
 import org.eclipse.mylyn.wikitext.core.parser.DocumentBuilder;
 import org.eclipse.mylyn.wikitext.core.parser.MarkupParser;
@@ -37,7 +38,9 @@ public class CommonMarkLanguage extends MarkupLanguage {
 		}
 
 		SourceBlocks sourceBlocks = CommonMark.sourceBlocks();
-		ProcessingContext context = sourceBlocks.createContext(LineSequence.create(markupContent));
+
+		ProcessingContext context = createContext(sourceBlocks, markupContent);
+
 		sourceBlocks.process(context, builder, LineSequence.create(markupContent));
 
 		if (asDocument) {
@@ -45,4 +48,9 @@ public class CommonMarkLanguage extends MarkupLanguage {
 		}
 	}
 
+	private ProcessingContext createContext(SourceBlocks sourceBlocks, String markupContent) {
+		ProcessingContextBuilder contextBuilder = ProcessingContext.builder();
+		sourceBlocks.createContext(contextBuilder, LineSequence.create(markupContent));
+		return contextBuilder.build();
+	}
 }