From c0eae29a415d2a1247a67059e0534cef6e936521 Mon Sep 17 00:00:00 2001
From: Karol Stasiak <karol.m.stasiak@gmail.com>
Date: Mon, 21 Sep 2020 00:14:39 +0200
Subject: [PATCH] Minor compilation speed optimization

---
 src/main/scala/millfork/env/Environment.scala | 7 ++++++-
 src/main/scala/millfork/node/Node.scala       | 1 +
 src/main/scala/millfork/parser/MfParser.scala | 2 +-
 3 files changed, 8 insertions(+), 2 deletions(-)

diff --git a/src/main/scala/millfork/env/Environment.scala b/src/main/scala/millfork/env/Environment.scala
index e7fb1ed8..5a225469 100644
--- a/src/main/scala/millfork/env/Environment.scala
+++ b/src/main/scala/millfork/env/Environment.scala
@@ -662,7 +662,12 @@ class Environment(val parent: Option[Environment], val prefix: String, val cpuFa
 
   def eval(e: Expression, vars: Map[String, Constant]): Option[Constant] = evalImpl(e, Some(vars))
 
-  def eval(e: Expression): Option[Constant] = evalImpl(e, None)
+  def eval(e: Expression): Option[Constant] = {
+    if (e.constantValueCache ne null) return e.constantValueCache
+    val cv = evalImpl(e, None)
+    e.constantValueCache = cv
+    cv
+  }
 
   //noinspection ScalaUnnecessaryParentheses,ZeroIndexToHead
   private def evalImpl(e: Expression, vv: Option[Map[String, Constant]]): Option[Constant] = try{{
diff --git a/src/main/scala/millfork/node/Node.scala b/src/main/scala/millfork/node/Node.scala
index a1679d75..d43d0f67 100644
--- a/src/main/scala/millfork/node/Node.scala
+++ b/src/main/scala/millfork/node/Node.scala
@@ -54,6 +54,7 @@ sealed trait Expression extends Node {
   def #-#(that: Expression): Expression = SumExpression(List(false -> this, true -> that), decimal = false)
 
   @transient var typeCache: Type = _
+  @transient var constantValueCache: Option[Constant] = _
 }
 
 case class ConstantArrayElementExpression(constant: Constant) extends Expression {
diff --git a/src/main/scala/millfork/parser/MfParser.scala b/src/main/scala/millfork/parser/MfParser.scala
index b790a6b1..00288236 100644
--- a/src/main/scala/millfork/parser/MfParser.scala
+++ b/src/main/scala/millfork/parser/MfParser.scala
@@ -806,7 +806,7 @@ object MfParser {
   val identifierTail: P[String] =
     CharsWhileIn("ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz_.1234567890", min = 1).rep(min = 1, sep = "$").!
 
-  val identifier: P[String] = (letter ~ ("$".? ~ identifierTail).?).!.opaque("<identifier>")
+  val identifier: P[String] = (letter ~ ("$".? ~ identifierTail).?).!.map(_.intern()).opaque("<identifier>")
 
   val doubleQuotedString: P[String] = P("\"" ~/ CharsWhile(c => c != '\"' && c != '\n' && c != '\r').?.! ~ "\"")