Migrate to use of parse time

So that we no longer rely on the feature to do begin time before a node.

src/Raku/ast/begintime.rakumod

@@ -18,25 +18,9 @@ class RakuAST::BeginTime
 
     # Ensure the begin-time effects are performed.
     method ensure-begin-performed(RakuAST::Resolver $resolver, RakuAST::IMPL::QASTContext $context, int :$phase) {
-        if nqp::can(self, 'PERFORM-BEGIN-BEFORE-CHILDREN') || nqp::can(self, 'PERFORM-BEGIN-AFTER-CHILDREN') {
-            if $phase == 0 && self.is-begin-performed-before-children || $phase == 1 {
-                unless $!begin-performed +& 1 {
-                    self.PERFORM-BEGIN-BEFORE-CHILDREN($resolver, $context);
-                    nqp::bindattr_i(self, RakuAST::BeginTime, '$!begin-performed',  $!begin-performed +| 1);
-                }
-            }
-            if $phase == 0 && self.is-begin-performed-after-children || $phase == 2 {
-                unless $!begin-performed +& 2 {
-                    self.PERFORM-BEGIN-AFTER-CHILDREN($resolver, $context);
-                    nqp::bindattr_i(self, RakuAST::BeginTime, '$!begin-performed', $!begin-performed +| 2);
-                }
-            }
-        }
-        else {
-            unless $!begin-performed {
-                self.PERFORM-BEGIN($resolver, $context);
-                nqp::bindattr_i(self, RakuAST::BeginTime, '$!begin-performed', 3);
-            }
+        unless $!begin-performed {
+            self.PERFORM-BEGIN($resolver, $context);
+            nqp::bindattr_i(self, RakuAST::BeginTime, '$!begin-performed', 3);
         }
         Nil
     }

src/Raku/ast/code.rakumod

@@ -1323,6 +1323,7 @@ class RakuAST::Routine
   is RakuAST::AttachTarget
   is RakuAST::PlaceholderParameterOwner
   is RakuAST::ImplicitLookups
+  is RakuAST::ParseTime
   is RakuAST::BeginTime
   is RakuAST::TraitTarget
   is RakuAST::ScopePhaser
@@ -1405,10 +1406,7 @@ class RakuAST::Routine
         $routine
     }
 
-    method is-begin-performed-before-children() { True }
-    method is-begin-performed-after-children() { True }
-
-    method PERFORM-BEGIN-BEFORE-CHILDREN(RakuAST::Resolver $resolver, RakuAST::IMPL::QASTContext $context) {
+    method PERFORM-PARSE(RakuAST::Resolver $resolver, RakuAST::IMPL::QASTContext $context) {
         my $placeholder-signature := self.placeholder-signature;
         if $placeholder-signature {
             $placeholder-signature.IMPL-ENSURE-IMPLICITS;
@@ -1418,7 +1416,7 @@ class RakuAST::Routine
         }
     }
 
-    method PERFORM-BEGIN-AFTER-CHILDREN(RakuAST::Resolver $resolver, RakuAST::IMPL::QASTContext $context) {
+    method PERFORM-BEGIN(RakuAST::Resolver $resolver, RakuAST::IMPL::QASTContext $context) {
         # Make sure that our placeholder signature has resolutions performed.
         my $placeholder-signature := self.placeholder-signature;
         if $placeholder-signature {
@@ -1769,10 +1767,7 @@ class RakuAST::Methodish
         nqp::bindattr(self, RakuAST::Code, '$!resolver', $resolver.clone);
     }
 
-    method is-begin-performed-before-children() { True }
-    method is-begin-performed-after-children() { True }
-
-    method PERFORM-BEGIN-BEFORE-CHILDREN(RakuAST::Resolver $resolver, RakuAST::IMPL::QASTContext $context) {
+    method PERFORM-PARSE(RakuAST::Resolver $resolver, RakuAST::IMPL::QASTContext $context) {
         my $placeholder-signature := self.placeholder-signature;
         if $placeholder-signature {
             $placeholder-signature.set-is-on-method(True);
@@ -1797,7 +1792,7 @@ class RakuAST::Methodish
         }
     }
 
-    method PERFORM-BEGIN-AFTER-CHILDREN(RakuAST::Resolver $resolver, RakuAST::IMPL::QASTContext $context) {
+    method PERFORM-BEGIN(RakuAST::Resolver $resolver, RakuAST::IMPL::QASTContext $context) {
         if nqp::getattr(self, RakuAST::Routine, '$!package') {
             nqp::getattr(self, RakuAST::Routine, '$!package').ATTACH-METHOD(self);
         }

src/Raku/ast/package.rakumod

@@ -5,7 +5,7 @@ class RakuAST::Package
   is RakuAST::IMPL::ImmediateBlockUser
   is RakuAST::Declaration
   is RakuAST::AttachTarget
-  is RakuAST::BeginTime
+  is RakuAST::ParseTime
   is RakuAST::TraitTarget
   is RakuAST::ImplicitBlockSemanticsProvider
   is RakuAST::LexicalScope
@@ -170,17 +170,14 @@ class RakuAST::Package
         Nil
     }
 
-    # We install the name before parsing the class body.
-    method is-begin-performed-before-children() { True }
-
     method IMPL-GENERATE-LEXICAL-DECLARATION(RakuAST::Name $name, Mu $type-object) {
         RakuAST::Declaration::LexicalPackage.new:
             :lexical-name($name),
             :compile-time-value($type-object),
             :package(self);
     }
 
-    method PERFORM-BEGIN(RakuAST::Resolver $resolver, RakuAST::IMPL::QASTContext $context) {
+    method PERFORM-PARSE(RakuAST::Resolver $resolver, RakuAST::IMPL::QASTContext $context) {
          # Note that this early return is actually not effective as the begin handler will
          # already be run when the parser enters the package and we only know that it's a
          # stub when we are done parsing the body.

src/Raku/ast/parsetime.rakumod

@@ -21,4 +21,43 @@ class RakuAST::ParseTime
             nqp::bindattr_i(self, RakuAST::ParseTime, '$!parse-performed', 1);
         }
     }
+
+    # Called when a BEGIN-time construct needs to evaluate code. Tries to
+    # interpret simple things to avoid the cost of compilation.
+    method IMPL-BEGIN-TIME-EVALUATE(RakuAST::Node $code, RakuAST::Resolver $resolver, RakuAST::IMPL::QASTContext $context) {
+        $code.IMPL-CHECK($resolver, $context, False);
+        if $code.IMPL-CAN-INTERPRET {
+            $code.IMPL-INTERPRET(RakuAST::IMPL::InterpContext.new)
+        }
+        elsif nqp::istype($code, RakuAST::Code) {
+            $code.meta-object;
+        }
+        elsif nqp::istype($code, RakuAST::Expression) {
+            my $thunk := RakuAST::ExpressionThunk.new;
+            $code.wrap-with-thunk($thunk);
+            $thunk.IMPL-STUB-CODE($resolver, $context);
+            $thunk.IMPL-QAST-BLOCK($context, :expression($code));
+            $thunk.meta-object()()
+        }
+        else {
+            nqp::die('BEGIN time evaluation only supported for simple constructs so far')
+        }
+    }
+
+    # Called when a BEGIN-time construct wants to evaluate a resolved code
+    # with a set of arguments.
+    method IMPL-BEGIN-TIME-CALL(RakuAST::Node $callee, RakuAST::ArgList $args,
+            RakuAST::Resolver $resolver, RakuAST::IMPL::QASTContext $context) {
+        if $callee.is-resolved && nqp::istype($callee.resolution, RakuAST::CompileTimeValue) &&
+                $args.IMPL-CAN-INTERPRET {
+            my $resolved := $callee.resolution.compile-time-value;
+            my @args := $args.IMPL-INTERPRET(RakuAST::IMPL::InterpContext.new);
+            my @pos := @args[0];
+            my %named := @args[1];
+            return $resolved(|@pos, |%named);
+        }
+        else {
+            nqp::die('BEGIN time calls only supported for simple constructs so far')
+        }
+    }
 }

src/Raku/ast/type.rakumod

@@ -673,9 +673,7 @@ class RakuAST::Type::Subset
             :scope(self.scope);
     }
 
-    method is-begin-performed-after-children() { True }
-
-    method PERFORM-BEGIN-AFTER-CHILDREN(RakuAST::Resolver $resolver, RakuAST::IMPL::QASTContext $context) {
+    method PERFORM-BEGIN(RakuAST::Resolver $resolver, RakuAST::IMPL::QASTContext $context) {
         self.apply-traits($resolver, $context, self);
 
         my $block := $!block;