12 files changed, 88 insertions, 9 deletions
diff --git a/include/cru/parse/ParsingAlgorithm.hpp b/include/cru/parse/ParsingAlgorithm.hpp
index 1ea30a80..acca159e 100644
--- a/include/cru/parse/ParsingAlgorithm.hpp
+++ b/include/cru/parse/ParsingAlgorithm.hpp
@@ -14,7 +14,7 @@ class ParsingAlgorithm {
   CRU_DELETE_COPY(ParsingAlgorithm)
   CRU_DELETE_MOVE(ParsingAlgorithm)
 
-  ~ParsingAlgorithm() = default;
+  virtual ~ParsingAlgorithm() = default;
 
   virtual bool CanHandle(Grammar* grammar) const = 0;
   virtual ParsingAlgorithmContext* CreateContext(Grammar* grammar) const = 0;
diff --git a/include/cru/parse/ParsingAlgorithmContext.hpp b/include/cru/parse/ParsingAlgorithmContext.hpp
index 072203ec..f67ccbbc 100644
--- a/include/cru/parse/ParsingAlgorithmContext.hpp
+++ b/include/cru/parse/ParsingAlgorithmContext.hpp
@@ -1,5 +1,8 @@
 #pragma once
+#include <vector>
 #include "Grammar.hpp"
+#include "cru/parse/ParsingTreeNode.hpp"
+#include "cru/parse/Terminal.hpp"
 
 namespace cru::parse {
 class ParsingAlgorithm;
@@ -9,15 +12,17 @@ class ParsingAlgorithm;
 // contain any state machine.
 class ParsingAlgorithmContext {
  public:
-  ParsingAlgorithmContext(Grammar* grammar, ParsingAlgorithm* algorithm);
+  ParsingAlgorithmContext(Grammar* grammar, const ParsingAlgorithm* algorithm);
 
   CRU_DELETE_COPY(ParsingAlgorithmContext)
   CRU_DELETE_MOVE(ParsingAlgorithmContext)
 
-  ~ParsingAlgorithmContext();
+  virtual ~ParsingAlgorithmContext();
+
+  virtual ParsingTreeNode* Parse(const std::vector<Terminal*>& input) = 0;
 
  private:
   Grammar* grammar_;
-  ParsingAlgorithm* algorithm_;
+  const ParsingAlgorithm* algorithm_;
 };
 }  // namespace cru::parse
diff --git a/include/cru/parse/ParsingContext.hpp b/include/cru/parse/ParsingContext.hpp
index 369acf41..ebb7115a 100644
--- a/include/cru/parse/ParsingContext.hpp
+++ b/include/cru/parse/ParsingContext.hpp
@@ -1,12 +1,13 @@
 #pragma once
 #include "ParsingAlgorithmContext.hpp"
+#include "cru/parse/ParsingTreeNode.hpp"
 
 namespace cru::parse {
 // A parsing context contains all info that a program needs to know when parsing
 // a input sequence of terminals.
 class ParsingContext {
  public:
-  ParsingContext(ParsingAlgorithmContext* parsing_algorithm_context,
+  ParsingContext(const ParsingAlgorithmContext* parsing_algorithm_context,
                  std::vector<Terminal*> input);
 
   CRU_DELETE_COPY(ParsingContext)
@@ -15,7 +16,7 @@ class ParsingContext {
   ~ParsingContext();
 
  private:
-  ParsingAlgorithmContext* parsing_algorithm_context_;
+  const ParsingAlgorithmContext* parsing_algorithm_context_;
   std::vector<Terminal*> input_;
 };
 }  // namespace cru::parse
diff --git a/include/cru/parse/RecursiveDescentAlgorithm.hpp b/include/cru/parse/RecursiveDescentAlgorithm.hpp
new file mode 100644
index 00000000..c12a84f6
--- /dev/null
+++ b/include/cru/parse/RecursiveDescentAlgorithm.hpp
@@ -0,0 +1,19 @@
+#pragma once
+
+#include "ParsingAlgorithm.hpp"
+
+namespace cru::parse {
+class RecursiveDescentAlgorithm : public ParsingAlgorithm {
+ public:
+  RecursiveDescentAlgorithm() = default;
+
+  CRU_DELETE_COPY(RecursiveDescentAlgorithm)
+  CRU_DELETE_MOVE(RecursiveDescentAlgorithm)
+
+  ~RecursiveDescentAlgorithm() override = default;
+
+ public:
+  bool CanHandle(Grammar* grammar) const override;
+  ParsingAlgorithmContext* CreateContext(Grammar* grammar) const override;
+};
+}  // namespace cru::parse
diff --git a/include/cru/parse/RecursiveDescentAlgorithmContext.hpp b/include/cru/parse/RecursiveDescentAlgorithmContext.hpp
new file mode 100644
index 00000000..1b888da9
--- /dev/null
+++ b/include/cru/parse/RecursiveDescentAlgorithmContext.hpp
@@ -0,0 +1,22 @@
+#pragma once
+
+#include "ParsingAlgorithmContext.hpp"
+#include "cru/parse/ParsingTreeNode.hpp"
+#include "cru/parse/RecursiveDescentAlgorithm.hpp"
+#include "cru/parse/Terminal.hpp"
+
+namespace cru::parse {
+class RecursiveDescentAlgorithmContext : public ParsingAlgorithmContext {
+ public:
+  RecursiveDescentAlgorithmContext(Grammar* grammar,
+                                   const RecursiveDescentAlgorithm* algorithm);
+
+  CRU_DELETE_COPY(RecursiveDescentAlgorithmContext)
+  CRU_DELETE_MOVE(RecursiveDescentAlgorithmContext)
+
+  ~RecursiveDescentAlgorithmContext() override;
+
+ public:
+  ParsingTreeNode* Parse(const std::vector<Terminal*>& input) override;
+};
+}  // namespace cru::parse
diff --git a/src/CMakeLists.txt b/src/CMakeLists.txt
index 5059cc82..d16c075e 100644
--- a/src/CMakeLists.txt
+++ b/src/CMakeLists.txt
@@ -9,5 +9,5 @@ elseif (APPLE)
 endif()
 
 add_subdirectory(ui)
-
 add_subdirectory(parse)
+add_subdirectory(xml)
diff --git a/src/parse/CMakeLists.txt b/src/parse/CMakeLists.txt
index 631c9881..72bac707 100644
--- a/src/parse/CMakeLists.txt
+++ b/src/parse/CMakeLists.txt
@@ -6,6 +6,8 @@ add_library(cru_parse SHARED
 	ParsingContext.cpp
 	ParsingTreeNode.cpp
 	Production.cpp
+	RecursiveDescentAlgorithm.cpp
+	RecursiveDescentAlgorithmContext.cpp
 	Symbol.cpp
 	Terminal.cpp
 	Token.cpp
diff --git a/src/parse/ParsingAlgorithmContext.cpp b/src/parse/ParsingAlgorithmContext.cpp
index 98e2343b..686ba3e5 100644
--- a/src/parse/ParsingAlgorithmContext.cpp
+++ b/src/parse/ParsingAlgorithmContext.cpp
@@ -2,7 +2,7 @@
 
 namespace cru::parse {
 ParsingAlgorithmContext::ParsingAlgorithmContext(Grammar* grammar,
-                                                 ParsingAlgorithm* algorithm)
+                                                 const ParsingAlgorithm* algorithm)
     : grammar_(grammar), algorithm_(algorithm) {}
 
 ParsingAlgorithmContext::~ParsingAlgorithmContext() {}
diff --git a/src/parse/ParsingContext.cpp b/src/parse/ParsingContext.cpp
index aafaa65b..25a7a133 100644
--- a/src/parse/ParsingContext.cpp
+++ b/src/parse/ParsingContext.cpp
@@ -3,7 +3,7 @@
 
 namespace cru::parse {
 ParsingContext::ParsingContext(
-    ParsingAlgorithmContext* parsing_algorithm_context,
+    const ParsingAlgorithmContext* parsing_algorithm_context,
     std::vector<Terminal*> input)
     : parsing_algorithm_context_(parsing_algorithm_context),
       input_(std::move(input)) {}
diff --git a/src/parse/RecursiveDescentAlgorithm.cpp b/src/parse/RecursiveDescentAlgorithm.cpp
new file mode 100644
index 00000000..a6549f8a
--- /dev/null
+++ b/src/parse/RecursiveDescentAlgorithm.cpp
@@ -0,0 +1,14 @@
+#include "cru/parse/RecursiveDescentAlgorithm.hpp"
+#include "cru/parse/ParsingAlgorithmContext.hpp"
+#include "cru/parse/RecursiveDescentAlgorithmContext.hpp"
+
+namespace cru::parse {
+bool RecursiveDescentAlgorithm::CanHandle(Grammar *grammar) const {
+  return true;
+}
+
+ParsingAlgorithmContext *RecursiveDescentAlgorithm::CreateContext(
+    Grammar *grammar) const {
+  return new RecursiveDescentAlgorithmContext(grammar, this);
+}
+}  // namespace cru::parse
diff --git a/src/parse/RecursiveDescentAlgorithmContext.cpp b/src/parse/RecursiveDescentAlgorithmContext.cpp
new file mode 100644
index 00000000..8de0abc4
--- /dev/null
+++ b/src/parse/RecursiveDescentAlgorithmContext.cpp
@@ -0,0 +1,16 @@
+#include "cru/parse/RecursiveDescentAlgorithmContext.hpp"
+#include "cru/parse/ParsingTreeNode.hpp"
+
+namespace cru::parse {
+RecursiveDescentAlgorithmContext::RecursiveDescentAlgorithmContext(
+    Grammar* grammar, const RecursiveDescentAlgorithm* algorithm)
+    : ParsingAlgorithmContext(grammar, algorithm) {}
+
+RecursiveDescentAlgorithmContext::~RecursiveDescentAlgorithmContext() = default;
+
+ParsingTreeNode* RecursiveDescentAlgorithmContext::Parse(
+    const std::vector<Terminal*>& input) {
+  // TODO: Implement this.
+  return nullptr;
+}
+}  // namespace cru::parse
diff --git a/src/xml/CMakeLists.txt b/src/xml/CMakeLists.txt
new file mode 100644
index 00000000..e69de29b
--- /dev/null
+++ b/src/xml/CMakeLists.txt