Indentation support for the ANTLR parser (as discussed in #192) (#194)

Indentation support for the ANTLR parser
    - some clean-up of the parser code (TODO: file input could be improved, more clean-up)
    - get rid of Translator and specify all syntactic rules in antlr4 grammer
    - support for else-when shorthand in the grammar
    - rename Begin to Block which makes more sense

1 files changed, 33 insertions, 14 deletions

diff --git a/src/main/scala/firrtl/Parser.scala b/src/main/scala/firrtl/Parser.scala
index dc8d6875..aa6ea63f 100644
--- a/src/main/scala/firrtl/Parser.scala
+++ b/src/main/scala/firrtl/Parser.scala
@@ -26,39 +26,53 @@ MODIFICATIONS.
 */
 package firrtl
 
-import org.antlr.v4.runtime._;
-import org.antlr.v4.runtime.atn._;
+import java.io.{ByteArrayInputStream, SequenceInputStream}
+
+import org.antlr.v4.runtime._
+import org.antlr.v4.runtime.atn._
 import com.typesafe.scalalogging.LazyLogging
 import firrtl.ir._
-import Utils.{time}
-import antlr._
+import firrtl.Utils.time
+import firrtl.antlr.{FIRRTLParser, _}
 
 class ParserException(message: String) extends Exception(message)
+
 case class ParameterNotSpecifiedException(message: String) extends ParserException(message)
+
 case class ParameterRedefinedException(message: String) extends ParserException(message)
+
 case class InvalidStringLitException(message: String) extends ParserException(message)
+
 case class InvalidEscapeCharException(message: String) extends ParserException(message)
 
-object Parser extends LazyLogging
-{
+
+object Parser extends LazyLogging {
   /** Takes Iterator over lines of FIRRTL, returns FirrtlNode (root node is Circuit) */
   def parse(lines: Iterator[String], infoMode: InfoMode = UseInfo): Circuit = {
-    val fixedInput = time("Translator") { Translator.addBrackets(lines) }
-    val antlrStream = new ANTLRInputStream(fixedInput.result)
-    val lexer = new FIRRTLLexer(antlrStream)
-    val tokens = new CommonTokenStream(lexer)
-    val parser = new FIRRTLParser(tokens)
 
-    time("ANTLR Parser") { parser.getInterpreter.setPredictionMode(PredictionMode.SLL) }
+    val parser = {
+      import scala.collection.JavaConverters._
+      val inStream = new SequenceInputStream(
+        lines.map{s => new ByteArrayInputStream((s + "\n").getBytes("UTF-8")) }.asJavaEnumeration
+      )
+      val lexer = new FIRRTLLexer(new ANTLRInputStream(inStream))
+      new FIRRTLParser(new CommonTokenStream(lexer))
+    }
+
+    time("ANTLR Parser") {
+      parser.getInterpreter.setPredictionMode(PredictionMode.SLL)
+    }
 
     // Concrete Syntax Tree
     val cst = parser.circuit
 
     val numSyntaxErrors = parser.getNumberOfSyntaxErrors
-    if (numSyntaxErrors > 0) throw new ParserException(s"${numSyntaxErrors} syntax error(s) detected")
+    if (numSyntaxErrors > 0) throw new ParserException(s"$numSyntaxErrors syntax error(s) detected")
 
     val visitor = new Visitor(infoMode)
-    val ast = time("Visitor") { visitor.visit(cst) } match {
+    val ast = time("Visitor") {
+      visitor.visit(cst)
+    } match {
       case c: Circuit => c
       case x => throw new ClassCastException("Error! AST not rooted with Circuit node!")
     }
@@ -69,8 +83,13 @@ object Parser extends LazyLogging
   def parse(lines: Seq[String]): Circuit = parse(lines.iterator)
 
   sealed abstract class InfoMode
+
   case object IgnoreInfo extends InfoMode
+
   case object UseInfo extends InfoMode
+
   case class GenInfo(filename: String) extends InfoMode
+
   case class AppendInfo(filename: String) extends InfoMode
+
 }