basis for a resident compiler

unstable, but can be tested with -Dsbt.resident.limit=n
 n is the maximum Globals kept around

interface/src/main/java/xsbti/compile/CachedCompiler.java

@@ -0,0 +1,11 @@
+package xsbti.compile;
+
+import xsbti.AnalysisCallback;
+import xsbti.Logger;
+import xsbti.Reporter;
+import java.io.File;
+
+public interface CachedCompiler
+{
+	public void run(File[] sources, DependencyChanges cpChanges, AnalysisCallback callback, Logger log, Reporter delegate);
+}

interface/src/main/java/xsbti/compile/CachedCompilerProvider.java

@@ -0,0 +1,10 @@
+package xsbti.compile;
+
+import xsbti.Logger;
+import xsbti.Reporter;
+
+public interface CachedCompilerProvider
+{
+	ScalaInstance scalaInstance();
+	CachedCompiler newCachedCompiler(String[] arguments, Logger log, Reporter reporter);
+}

interface/src/main/java/xsbti/compile/DependencyChanges.java

@@ -0,0 +1,13 @@
+package xsbti.compile;
+
+	import java.io.File;
+
+// only includes changes to dependencies outside of the project
+public interface DependencyChanges
+{
+	boolean isEmpty();
+	// class files or jar files
+	File[] modifiedBinaries();
+	// class names
+	String[] modifiedClasses();
+}

interface/src/main/java/xsbti/compile/GlobalsCache.java

@@ -0,0 +1,10 @@
+package xsbti.compile;
+
+import xsbti.Logger;
+import xsbti.Reporter;
+
+public interface GlobalsCache
+{
+	public CachedCompiler apply(String[] args, boolean forceNew, CachedCompilerProvider provider, Logger log, Reporter reporter);
+	public void clear();
+}

interface/src/main/java/xsbti/compile/Setup.java

@@ -21,4 +21,6 @@ public interface Setup<Analysis>
 	* This file can be removed to force a full recompilation. 
 	* The file should be unique and not shared between compilations. */
 	File cacheFile();
+
+	GlobalsCache cache();
 }