Provide a way to merge repositories

Suppose you have multiple repositories in SVN that you want to merge into
a single one in GIT, it can get very messy to handle all the special-case
rules.

Instead, we introduce a new "forwarding repository" concept, which looks like

  repository subordinate
	repository unified
	prefix foo/
  end repository

This forwards all commits on the "subordinate" SVN tree to the "unified" GIT
tree, with each file prefixed with "foo/".

5 files changed, 73 insertions, 3 deletions

diff --git a/src/main.cpp b/src/main.cpp
index ff11255..3feb3cf 100644
--- a/src/main.cpp
+++ b/src/main.cpp
@@ -124,6 +124,8 @@ int main(int argc, char **argv)
     int min_rev = 1;
     foreach (Rules::Repository rule, rules.repositories()) {
 	Repository *repo = makeRepository(rule, repositories);
+	if (!repo)
+	    return EXIT_FAILURE;
         repositories.insert(rule.name, repo);
 
 	int repo_next = repo->setupIncremental(cutoff);
diff --git a/src/repository.cpp b/src/repository.cpp
index f5b7a50..760fc1a 100644
--- a/src/repository.cpp
+++ b/src/repository.cpp
@@ -123,6 +123,59 @@ private:
     Q_DISABLE_COPY(FastImportRepository)
 };
 
+class PrefixingRepository : public Repository
+{
+    Repository *repo;
+    QString prefix;
+public:
+    class Transaction : public Repository::Transaction
+    {
+        Q_DISABLE_COPY(Transaction)
+
+	Repository::Transaction *txn;
+	QString prefix;
+    public:
+	Transaction(Repository::Transaction *t, const QString &p) : txn(t), prefix(p) {}
+	~Transaction() { delete txn; }
+        void commit() { txn->commit(); }
+
+        void setAuthor(const QByteArray &author) { txn->setAuthor(author); }
+        void setDateTime(uint dt) { txn->setDateTime(dt); }
+        void setLog(const QByteArray &log) { txn->setLog(log); }
+
+	void noteCopyFromBranch (const QString &prevbranch, int revFrom)
+	{ txn->noteCopyFromBranch(prevbranch, revFrom); }
+
+        void deleteFile(const QString &path) { txn->deleteFile(prefix + path); }
+        QIODevice *addFile(const QString &path, int mode, qint64 length)
+        { return txn->addFile(prefix + path, mode, length); }
+    };
+
+    PrefixingRepository(Repository *r, const QString &p) : repo(r), prefix(p) {}
+
+    int setupIncremental(int &) { return 1; }
+    void restoreLog() {}
+
+    int createBranch(const QString &branch, int revnum,
+		     const QString &branchFrom, int revFrom)
+    { return repo->createBranch(branch, revnum, branchFrom, revFrom); }
+
+    int deleteBranch(const QString &branch, int revnum)
+    { return repo->deleteBranch(branch, revnum); }
+
+    Repository::Transaction *newTransaction(const QString &branch, const QString &svnprefix, int revnum)
+    {
+	Repository::Transaction *t = repo->newTransaction(branch, svnprefix, revnum);
+	return new Transaction(t, prefix);
+    }
+
+    void createAnnotatedTag(const QString &name, const QString &svnprefix, int revnum,
+			    const QByteArray &author, uint dt,
+			    const QByteArray &log)
+    { repo->createAnnotatedTag(name, svnprefix, revnum, author, dt, log); }
+    void finalizeTags() { /* loop that called this will invoke it on 'repo' too */ }
+};
+
 class ProcessCache: QLinkedList<FastImportRepository *>
 {
 public:
@@ -151,7 +204,14 @@ static ProcessCache processCache;
 
 Repository *makeRepository(const Rules::Repository &rule, const QHash<QString, Repository *> &repositories)
 {
-    return new FastImportRepository(rule);
+    if (rule.forwardTo.isEmpty())
+	return new FastImportRepository(rule);
+    Repository *r = repositories[rule.forwardTo];
+    if (!r) {
+	qCritical() << "no repository with name" << rule.forwardTo << "found at line" << rule.lineNumber;
+	return r;
+    }
+    return new PrefixingRepository(r, rule.prefix);
 }
 
 FastImportRepository::FastImportRepository(const Rules::Repository &rule)
diff --git a/src/repository.h b/src/repository.h
index 590ef0e..e07d184 100644
--- a/src/repository.h
+++ b/src/repository.h
@@ -49,7 +49,6 @@ public:
     virtual void restoreLog() = 0;
     virtual ~Repository() {}
 
-    virtual void reloadBranches() = 0;
     virtual int createBranch(const QString &branch, int revnum,
 			     const QString &branchFrom, int revFrom) = 0;
     virtual int deleteBranch(const QString &branch, int revnum) = 0;
diff --git a/src/ruleparser.cpp b/src/ruleparser.cpp
index 42334b7..d1f5cd4 100644
--- a/src/ruleparser.cpp
+++ b/src/ruleparser.cpp
@@ -81,7 +81,13 @@ void Rules::load()
 
                 repo.branches += branch;
                 continue;
-            } else if (line == "end repository") {
+            } else if (matchRepoLine.exactMatch(line)) {
+		repo.forwardTo = matchRepoLine.cap(1);
+		continue;
+	    } else if (matchPrefixLine.exactMatch(line)) {
+		repo.prefix = matchPrefixLine.cap(1);
+		continue;
+	    } else if (line == "end repository") {
                 m_repositories += repo;
 		{
 		    // clear out 'repo'
diff --git a/src/ruleparser.h b/src/ruleparser.h
index 8d0fcb2..95a508f 100644
--- a/src/ruleparser.h
+++ b/src/ruleparser.h
@@ -36,6 +36,9 @@ public:
         QList<Branch> branches;
         int lineNumber;
 
+	QString forwardTo;
+	QString prefix;
+
         Repository() : lineNumber(0) { }
     };