From 9634a735ee39d58096f57501e71c9308d8ae5e24 Mon Sep 17 00:00:00 2001
From: Alex Zenla <alex@fork.run>
Date: Tue, 5 Sep 2023 02:20:46 -0700
Subject: [PATCH] evaluator: ensure function definitions use root scope

---
 .../pizza/pork/evaluator/EvaluationContext.kt  | 10 +++++-----
 .../pizza/pork/evaluator/EvaluationVisitor.kt  |  8 ++++----
 .../gay/pizza/pork/evaluator/Evaluator.kt      |  2 +-
 .../kotlin/gay/pizza/pork/evaluator/Scope.kt   | 18 +++---------------
 4 files changed, 13 insertions(+), 25 deletions(-)

diff --git a/evaluator/src/main/kotlin/gay/pizza/pork/evaluator/EvaluationContext.kt b/evaluator/src/main/kotlin/gay/pizza/pork/evaluator/EvaluationContext.kt
index d1d5fa2..2114d61 100644
--- a/evaluator/src/main/kotlin/gay/pizza/pork/evaluator/EvaluationContext.kt
+++ b/evaluator/src/main/kotlin/gay/pizza/pork/evaluator/EvaluationContext.kt
@@ -10,10 +10,10 @@ class EvaluationContext(
 ) {
   private var isAlreadySetup = false
 
-  val internalScope = rootScope.fork()
-  val externalScope = rootScope.fork()
+  val internalRootScope = rootScope.fork()
+  val externalRootScope = rootScope.fork()
 
-  private val evaluationVisitor = EvaluationVisitor(internalScope)
+  private val evaluationVisitor = EvaluationVisitor(internalRootScope)
 
   fun setup() {
     if (isAlreadySetup) {
@@ -23,13 +23,13 @@ class EvaluationContext(
     val imports = compilationUnit.declarations.filterIsInstance<ImportDeclaration>()
     for (import in imports) {
       val evaluationContext = evaluationContextProvider.provideEvaluationContext(import.path.text)
-      internalScope.inherit(evaluationContext.externalScope)
+      internalRootScope.inherit(evaluationContext.externalRootScope)
     }
 
     for (definition in compilationUnit.definitions) {
       evaluationVisitor.visit(definition)
       if (definition.modifiers.export) {
-        externalScope.define(definition.symbol.id, internalScope.value(definition.symbol.id))
+        externalRootScope.define(definition.symbol.id, internalRootScope.value(definition.symbol.id))
       }
     }
   }
diff --git a/evaluator/src/main/kotlin/gay/pizza/pork/evaluator/EvaluationVisitor.kt b/evaluator/src/main/kotlin/gay/pizza/pork/evaluator/EvaluationVisitor.kt
index 699dfcc..ae47c62 100644
--- a/evaluator/src/main/kotlin/gay/pizza/pork/evaluator/EvaluationVisitor.kt
+++ b/evaluator/src/main/kotlin/gay/pizza/pork/evaluator/EvaluationVisitor.kt
@@ -2,7 +2,7 @@ package gay.pizza.pork.evaluator
 
 import gay.pizza.pork.ast.*
 
-class EvaluationVisitor(root: Scope) : NodeVisitor<Any> {
+class EvaluationVisitor(val root: Scope) : NodeVisitor<Any> {
   private var currentScope: Scope = root
 
   override fun visitIntLiteral(node: IntLiteral): Any = node.value
@@ -104,15 +104,15 @@ class EvaluationVisitor(root: Scope) : NodeVisitor<Any> {
   override fun visitFunctionDefinition(node: FunctionDefinition): Any {
     val blockFunction = visitBlock(node.block) as BlockFunction
     val function = CallableFunction { arguments ->
-      currentScope = currentScope.fork(inheritFastCache = true)
-      currentScope.fastVariableCache.put(node.symbol.id, currentScope.value(node.symbol.id))
+      val formerScope = currentScope
+      currentScope = root.fork()
       for ((index, argumentSymbol) in node.arguments.withIndex()) {
         currentScope.define(argumentSymbol.id, arguments.values[index])
       }
       try {
         return@CallableFunction blockFunction.call()
       } finally {
-        currentScope = currentScope.leave()
+        currentScope = formerScope
       }
     }
     currentScope.define(node.symbol.id, function)
diff --git a/evaluator/src/main/kotlin/gay/pizza/pork/evaluator/Evaluator.kt b/evaluator/src/main/kotlin/gay/pizza/pork/evaluator/Evaluator.kt
index e5fe1a0..8b37212 100644
--- a/evaluator/src/main/kotlin/gay/pizza/pork/evaluator/Evaluator.kt
+++ b/evaluator/src/main/kotlin/gay/pizza/pork/evaluator/Evaluator.kt
@@ -7,7 +7,7 @@ class Evaluator(val world: World, val scope: Scope) : EvaluationContextProvider
 
   fun evaluate(path: String): Scope {
     val context = provideEvaluationContext(path)
-    return context.externalScope
+    return context.externalRootScope
   }
 
   override fun provideEvaluationContext(path: String): EvaluationContext {
diff --git a/evaluator/src/main/kotlin/gay/pizza/pork/evaluator/Scope.kt b/evaluator/src/main/kotlin/gay/pizza/pork/evaluator/Scope.kt
index e736522..296bfff 100644
--- a/evaluator/src/main/kotlin/gay/pizza/pork/evaluator/Scope.kt
+++ b/evaluator/src/main/kotlin/gay/pizza/pork/evaluator/Scope.kt
@@ -1,15 +1,10 @@
 package gay.pizza.pork.evaluator
 
-class Scope(
-  val parent: Scope? = null,
-  inherits: List<Scope> = emptyList(),
-  val fastVariableCache: FastVariableCache = FastVariableCache()
-) {
+class Scope(val parent: Scope? = null, inherits: List<Scope> = emptyList()) {
   private val inherited = inherits.toMutableList()
   private val variables = mutableMapOf<String, Any>()
 
   fun define(name: String, value: Any) {
-    fastVariableCache.invalidate(name)
     if (variables.containsKey(name)) {
       throw RuntimeException("Variable '${name}' is already defined")
     }
@@ -17,11 +12,6 @@ class Scope(
   }
 
   fun value(name: String): Any {
-    val fastCached = fastVariableCache.lookup(name)
-    if (fastCached != FastVariableCache.NotFound) {
-      return fastCached
-    }
-
     val value = valueOrNotFound(name)
     if (value == NotFound) {
       throw RuntimeException("Variable '${name}' not defined.")
@@ -58,10 +48,8 @@ class Scope(
     return value.call(arguments)
   }
 
-  fun fork(inheritFastCache: Boolean = false): Scope {
-    val fastCache = if (inheritFastCache) fastVariableCache else FastVariableCache()
-    return Scope(this, fastVariableCache = fastCache)
-  }
+  fun fork(): Scope =
+    Scope(this)
 
   fun leave(): Scope {
     if (parent == null) {