From 672be2521196653fdeea7c123378526e904667f0 Mon Sep 17 00:00:00 2001
From: Tony Garnock-Jones <tonyg@leastfixedpoint.com>
Date: Sat, 11 Dec 2021 16:54:47 +0100
Subject: [PATCH] Autolink during...spawn

---
 packages/compiler/src/compiler/codegen.ts | 25 ++++++++++++++++-------
 packages/compiler/src/compiler/grammar.ts |  6 +++---
 2 files changed, 21 insertions(+), 10 deletions(-)

diff --git a/packages/compiler/src/compiler/codegen.ts b/packages/compiler/src/compiler/codegen.ts
index b88943e..5c745c7 100644
--- a/packages/compiler/src/compiler/codegen.ts
+++ b/packages/compiler/src/compiler/codegen.ts
@@ -16,6 +16,7 @@ import {
     Binder,
 
     compilePattern,
+    SpawnStatement,
 } from './grammar.js';
 
 export function stripShebang(items: Items): Items {
@@ -138,7 +139,16 @@ export function expand(tree: Items, ctx: ExpansionContext): Items {
     // following transformations matters.
 
     xf(ctx.parser.duringStatement, (s, t) => {
-        // TODO: untyped template
+        let spawn = match(ctx.parser.spawn, s.body, null);
+        if (spawn !== null) {
+            if (spawn.linkedToken !== null) {
+                ctx.emitError(`during ... spawn doesn't need "linked", it's always linked`,
+                              spawn.linkedToken);
+            }
+            spawn.linkedToken = getRange(s.body);
+        }
+        let body = (spawn == null) ? walk(s.body) : expandSpawn(spawn, t);
+
         const sa = compilePattern(s.pattern);
         return t`assertDataflow(() => ({
             target: currentSyndicateTarget,
@@ -148,7 +158,7 @@ export function expand(tree: Items, ctx: ExpansionContext): Items {
                     (${ctx.argDecl(t, '__vs', '__SYNDICATE__.AnyValue')}) => {
                         if (Array.isArray(__vs)) {
 ${joinItems(sa.captureBinders.map(binderTypeGuard(ctx, t)), '\n')}
-                            ${walk(s.body)}
+                            ${body}
                         }
                     }
                 ))
@@ -156,17 +166,18 @@ ${joinItems(sa.captureBinders.map(binderTypeGuard(ctx, t)), '\n')}
         }));`;
     });
 
-    xf(ctx.parser.spawn, (s, t) => {
+    function expandSpawn(spawn: SpawnStatement, t: TemplateFunction): Items {
         // TODO: parentBinders, parentInits
-        let body = walk(s.body);
         /*
         let assertions = (s.initialAssertions.length > 0)
             ? t`, new __SYNDICATE__.Set([${commaJoin(s.initialAssertions.map(walk))}])`
             : ``;
         */
-        const n = s.name === void 0 ? '' : t` __SYNDICATE__.Turn.activeFacet.actor.name = ${walk(s.name)};`;
-        return t`_spawn${s.isLink ? 'Link': ''}(() => {${n} ${body} });`;
-    });
+        const n = spawn.name === void 0 ? '' : t` __SYNDICATE__.Turn.activeFacet.actor.name = ${walk(spawn.name)};`;
+        return t`_spawn${spawn.linkedToken ? 'Link': ''}(() => {${n} ${walk(spawn.body)} });`;
+    }
+
+    xf(ctx.parser.spawn, expandSpawn);
 
     x(ctx.parser.fieldDeclarationStatement, (s, t) => {
         const ft = ctx.typescript ? t`<${s.field.type ?? '__SYNDICATE__.AnyValue'}>` : '';
diff --git a/packages/compiler/src/compiler/grammar.ts b/packages/compiler/src/compiler/grammar.ts
index e57e376..d07632a 100644
--- a/packages/compiler/src/compiler/grammar.ts
+++ b/packages/compiler/src/compiler/grammar.ts
@@ -30,7 +30,7 @@ export interface FacetSetupAction extends TurnAction {
 
 export interface SpawnStatement extends FacetSetupAction {
     name?: Expr;
-    isLink: boolean;
+    linkedToken: TokenBase | null;
     parentBinders: Binder[];
     parentInits: Expr[];
 }
@@ -207,12 +207,12 @@ export class SyndicateParser {
     // Principal: Turn
     readonly spawn: Pattern<SpawnStatement> =
         this.turnAction(o => {
-            o.isLink = false;
+            o.linkedToken = null;
             o.parentBinders = [];
             o.parentInits = [];
             o.body = [];
             return seq(atom('spawn'),
-                       option(map(atom('linked'), _ => o.isLink = true)),
+                       option(map(atom('linked'), tok => o.linkedToken = tok)),
                        option(seq(atom('named'), bind(o, 'name', this.headerExpr))),
                        repeat(alt(
                            /* seq(kw('asserting'), map(this.headerExpr, e => o.initialAssertions.push(e))), */