Fix error when parsing files with circular dependencies

Fix doesn't guarantee that compilation process will be successful if
output file was generated from source files with circular dependencies.
This is not in scope of this project. Circular dependencies shouldn't
occur in well organized projects.

This fix has minor side effect. Order of source files in generated
output file can slightly change.

Author: FastAlien

src/parse/CppFileMerger.ts

@@ -49,15 +49,16 @@ export default class CppFileMerger {
     const fileContent = readFile(filePath);
     const result = this.parser.parse(fileContent);
     result.systemIncludes.forEach(include => this.systemIncludes.add(include));
-    const currentDirectory = path.dirname(filePath);
-    const localIncludesContent = result.localIncludes.map(includeFilePath => {
-      return this.parseIncludedFile(includeFilePath, currentDirectory, filePath)
-    });
 
     if (result.processOnce) {
       this.processedOnce.add(filePath);
     }
 
+    const currentDirectory = path.dirname(filePath);
+    const localIncludesContent = result.localIncludes.map(includeFilePath => {
+      return this.parseIncludedFile(includeFilePath, currentDirectory, filePath)
+    });
+
     return [
       ...localIncludesContent,
       result.content

test/data/circularDependencies/expected.cpp

@@ -0,0 +1,8 @@
+#include <iostream>
+
+// second.hpp
+
+// first.hpp
+
+// main.cpp
+

test/data/circularDependencies/first.hpp

@@ -0,0 +1,7 @@
+#pragma once
+
+#include "second.hpp"
+
+#include <iostream>
+
+// first.hpp

test/data/circularDependencies/main.cpp

@@ -0,0 +1,5 @@
+#include "first.hpp"
+
+#include <iostream>
+
+// main.cpp

test/data/circularDependencies/second.hpp

@@ -0,0 +1,5 @@
+#pragma once
+
+#include "first.hpp"
+
+// second.hpp

test/data/complex/expected.cpp

@@ -12,8 +12,8 @@
 
 // main.cpp
 
-// zero.c
-
 // first.cpp
 
+// zero.c
+
 // second.cpp

test/unit/parse/CppFileMerger.test.ts

@@ -38,3 +38,14 @@ describe("Merging source files in subdirectories", () => {
     expect(content).toEqual(expected);
   });
 });
+
+describe("Merging files with circular dependencies", () => {
+  const dataDirectory = "test/data/circularDependencies";
+  const merger = new CppFileMerger();
+  const content = merger.parse(`${dataDirectory}/main.cpp`);
+
+  test("Generated content equals expected", () => {
+    const expected = fs.readFileSync(`${dataDirectory}/expected.cpp`, "utf-8");
+    expect(content).toEqual(expected);
+  });
+});