Stringified annotations (#367)

Restricts annotations to be string-based (and thus less typesafe)
Makes annotations more easily serializable and interact with Chisel

1 files changed, 74 insertions, 0 deletions

diff --git a/src/main/scala/firrtl/annotations/AnnotationUtils.scala b/src/main/scala/firrtl/annotations/AnnotationUtils.scala
new file mode 100644
index 00000000..6e6af81d
--- /dev/null
+++ b/src/main/scala/firrtl/annotations/AnnotationUtils.scala
@@ -0,0 +1,74 @@
+// See LICENSE for license details.
+
+package firrtl
+package annotations
+
+import firrtl.ir._
+
+object AnnotationUtils {
+  /** Returns true if a valid Module name */
+  val SerializedModuleName = """([a-zA-Z_][a-zA-Z_0-9~!@#$%^*\-+=?/]*)""".r
+  def validModuleName(s: String): Boolean = s match {
+    case SerializedModuleName(name) => true
+    case _ => false
+  }
+
+  /** Returns true if a valid component/subcomponent name */
+  val SerializedComponentName = """([a-zA-Z_][a-zA-Z_0-9\[\]\.~!@#$%^*\-+=?/]*)""".r
+  def validComponentName(s: String): Boolean = s match {
+    case SerializedComponentName(name) => true
+    case _ => false
+  }
+
+  /** Tokenizes a string with '[', ']', '.' as tokens, e.g.:
+   *  "foo.bar[boo.far]" becomes Seq("foo" "." "bar" "[" "boo" "." "far" "]")
+   */
+  def tokenize(s: String): Seq[String] = s.find(c => "[].".contains(c)) match {
+    case Some(_) =>
+      val i = s.indexWhere(c => "[].".contains(c))
+      s.slice(0, i) match {
+        case "" => Seq(s(i).toString) ++ tokenize(s.drop(i + 1))
+        case x => Seq(x, s(i).toString) ++ tokenize(s.drop(i + 1))
+      }
+    case None if s == "" => Nil
+    case None => Seq(s)
+  }
+
+  /** Given a serialized component/subcomponent reference, subindex, subaccess,
+   *  or subfield, return the corresponding IR expression.
+   *  E.g. "foo.bar" becomes SubField(Reference("foo", UnknownType), "bar", UnknownType)
+   */
+  def toExp(s: String): Expression = {
+    def parse(tokens: Seq[String]): Expression = {
+      val DecPattern = """([1-9]\d*)""".r
+      def findClose(tokens: Seq[String], index: Int, nOpen: Int): Seq[String] = {
+        if(index >= tokens.size) {
+          error("Cannot find closing bracket ]")
+        } else tokens(index) match {
+          case "[" => findClose(tokens, index + 1, nOpen + 1)
+          case "]" if nOpen == 1 => tokens.slice(1, index)
+          case "]" => findClose(tokens, index + 1, nOpen - 1)
+          case _ => findClose(tokens, index + 1, nOpen)
+        }
+      }
+      def buildup(e: Expression, tokens: Seq[String]): Expression = tokens match {
+        case "[" :: tail =>
+          val indexOrAccess = findClose(tokens, 0, 0)
+          val exp = indexOrAccess.head match {
+            case DecPattern(d) => SubIndex(e, d.toInt, UnknownType)
+            case _ => SubAccess(e, parse(indexOrAccess), UnknownType)
+          }
+          buildup(exp, tokens.drop(2 + indexOrAccess.size))
+        case "." :: tail =>
+          buildup(SubField(e, tokens(1), UnknownType), tokens.drop(2))
+        case Nil => e
+      }
+      val root = Reference(tokens.head, UnknownType)
+      buildup(root, tokens.tail)
+    }
+    if(validComponentName(s)) {
+      parse(tokenize(s))
+    } else error(s"Cannot convert $s into an expression.")
+  }
+}
+