Change firrtl.options API, add Phase

This breaks firrtl.options.Stage into a small type hierarchy:

  * Phase: something that transforms an AnnotationSeq
  * Stage extends Phase: a Phase with a Command Line Interface

Some of the old "common options" (input annotation file and target
directory) are moved into firrtl.options and provided as part of the Stage
class. Stage will automatically preprocess an input annotation sequence to
resolve all input annotation files and add a default target directory.

Minor changes:

  * Adds ViewException
  * Stops mixing in the DoNotTerminateOnExit trait into the default Shell
    parser
  * Add StageOptionsView

Signed-off-by: Schuyler Eldridge <schuyler.eldridge@ibm.com>

1 files changed, 20 insertions, 0 deletions

diff --git a/src/main/scala/firrtl/options/Phase.scala b/src/main/scala/firrtl/options/Phase.scala
new file mode 100644
index 00000000..22715bc2
--- /dev/null
+++ b/src/main/scala/firrtl/options/Phase.scala
@@ -0,0 +1,20 @@
+// See LICENSE for license details.
+
+package firrtl.options
+
+import firrtl.AnnotationSeq
+
+/** A transformation of an [[AnnotationSeq]]
+  *
+  * A [[Phase]] forms one block in the Chisel/FIRRTL Hardware Compiler Framework (HCF). Note that a [[Phase]] may
+  * consist of multiple phases internally.
+  */
+abstract class Phase {
+
+  /** A transformation of an [[AnnotationSeq]]
+    * @param annotations some annotations
+    * @return transformed annotations
+    */
+  def transform(annotations: AnnotationSeq): AnnotationSeq
+
+}