Tidy up scope display

4 files changed, 204 insertions, 38 deletions

diff --git a/graph/web/index.html b/graph/web/index.html
index 771d3d4a..a568cbc6 100644
--- a/graph/web/index.html
+++ b/graph/web/index.html
@@ -19,9 +19,12 @@
     .edge { fill:none; stroke-width:1.5; }
     .edge.CTRL { stroke-width:2; }
     .edge.ASSOC { stroke-dasharray:4 4; }
+    .edge.PARSER { stroke-dasharray:5 4; }
+    .parser rect { fill:#f6f0ff; stroke:#7956a5; stroke-width:1.5; stroke-dasharray:5 4; }
     .edge.selected { stroke-width:3.5; }
     .node { cursor:pointer; }
     .box { stroke:#758191; stroke-width:1; }
+    .node.held .box { stroke-dasharray:5 3; }
     .node.near .box { stroke:#c18221; stroke-width:2; }
     .node.focus .box { stroke:#9c4900; stroke-width:3; }
     .node.selected .box { stroke:#1569b9; stroke-width:3; }
@@ -29,6 +32,8 @@
     .label { font-size:12px; fill:#152330; font-weight:600; }
     .type { font-size:11px; fill:#455768; }
     .port { stroke:#536477; stroke-width:1; }
+    .row { stroke:#b6afcf; stroke-width:1; }
+    .bind { font-size:12px; fill:#152330; }
     .slot { font-size:10px; fill:#364352; paint-order:stroke; stroke:#fafbfc; stroke-width:3; }
     #detail { position:absolute; top:8px; right:8px; margin:0; padding:12px; max-width:320px;
       max-height:45%; overflow:auto; white-space:pre-wrap; overflow-wrap:anywhere;
diff --git a/graph/web/layout.js b/graph/web/layout.js
index 1cf9fb14..a277cb53 100644
--- a/graph/web/layout.js
+++ b/graph/web/layout.js
@@ -11,31 +11,94 @@ class GraphLayout {
     return chars.length > 44 ? chars.slice(0, 43).join("") + "…" : chars.join("");
   }
 
-  async run(snap) {
+  async run(snap, evt) {
     const nodes = snap.nodes.map(n => {
       const label = this.clip(n.label), type = this.clip(n.type);
-      const w = Math.ceil(Math.max(120, this.ctx.measureText(label).width + 24,
+      let w = Math.ceil(Math.max(120, this.ctx.measureText(label).width + 24,
         this.ctx.measureText(type).width + 24, (n.edges.length + 1) * 18));
-      const h = 62;
-      const ports = n.edges.map(e => ({
-        id: "n" + n.id + "i" + e.idx, x: w * (e.idx + 1) / (n.edges.length + 1) - 3,
-        y: -3, width: 6, height: 6, layoutOptions: {"elk.port.side": "NORTH"}
-      }));
-      ports.push({id: "n" + n.id + "o", x: w / 2 - 3, y: h - 3,
-        width: 6, height: 6, layoutOptions: {"elk.port.side": "SOUTH"}});
-      return {id: "n" + n.id, width: w, height: h, ports,
-        layoutOptions: {"elk.portConstraints": "FIXED_POS"}, n, label, type};
+      const scope = n.kind === "SCOPE";
+      const cols = scope ? n.edges.map(e => Math.ceil(Math.max(48,
+        this.ctx.measureText(e.label || "[" + e.idx + "]").width + 24))) : [];
+      if (scope) w = Math.ceil(Math.max(120, this.ctx.measureText(label).width + 24,
+        cols.reduce((sum, w) => sum + w, 0)));
+      return {id: "n" + n.id, width: w, height: 62,
+        ports: [], n, label, type, scope, cols, ox: 0, oy: 0};
     });
     const byId = new Map(nodes.map(n => [n.n.id, n]));
+    const parsing = evt?.phase === "Parse" && evt.kind !== "PHASE";
+    const roots = new Set(snap.roots);
+    const scopes = nodes.filter(n => n.scope);
+    const active = parsing ? byId.get(snap.scope) : null;
+    // Scope bindings count as users too. Scope ownership comes from parser
+    // roots; unfinished expression values are inferred from absent uses.
+    const used = new Set();
+    for (const n of snap.nodes) for (const e of n.edges) if (e.def) used.add(e.def);
+    const held = parsing ? nodes.filter(n =>
+      (n.n.proj || ["DATA", "MEM", "PHI"].includes(n.n.kind)) && !used.has(n.n.id)) : [];
+    for (const n of held) n.held = true;
+    const owned = [...held, ...scopes.filter(n => parsing && roots.has(n.n.id))];
+    const projs = new Map();
+    for (const n of nodes) {
+      const par = byId.get(n.n.proj?.par);
+      // A projection without its parent still gets a standalone box.
+      if (!par || par.n.proj) continue;
+      if (!projs.has(par)) projs.set(par, []);
+      projs.get(par).push(n);
+      n.par = par;
+    }
+    const groups = nodes.filter(n => !n.par).map(n => {
+      const slots = (projs.get(n) || []).sort((a, b) => a.n.proj.idx - b.n.proj.idx || a.n.id - b.n.id);
+      const parts = [n, ...slots];
+      if (slots.length) {
+        const w = slots.reduce((sum, p) => sum + p.width, 0);
+        n.width = Math.max(n.width, w);
+        const extra = (n.width - w) / slots.length;
+        let x = 0;
+        for (const p of slots) {
+          p.width += extra;
+          p.ox = x;
+          p.oy = n.height;
+          x += p.width;
+        }
+      }
+      const ports = [];
+      for (const p of parts) {
+        p.cell = slots.length > 0;
+        const extra = p.scope && p.cols.length ?
+          (p.width - p.cols.reduce((sum, w) => sum + w, 0)) / p.cols.length : 0;
+        let x = 0;
+        for (const [idx, e] of p.n.edges.entries()) {
+          // The parent/projection link is represented by the shared box.
+          if (p.par && e.idx === 0 && e.def === p.par.n.id) continue;
+          if (p.scope) {
+            const span = p.cols[idx] + extra;
+            ports.push({id: p.id + "i" + e.idx, x: x + span / 2 - 3, y: -3, span,
+              width: 6, height: 6, layoutOptions: {"elk.port.side": "NORTH"}});
+            x += span;
+            continue;
+          }
+          ports.push({id: p.id + "i" + e.idx, x: p.ox + p.width * (e.idx + 1) / (p.n.edges.length + 1) - 3,
+            y: p.oy - 3, width: 6, height: 6, layoutOptions: {"elk.port.side": "NORTH"}});
+        }
+        // Direct uses of the MultiNode attach to its header, projections below.
+        const side = p === n && slots.length ? "EAST" : "SOUTH";
+        ports.push({id: p.id + "o", x: p.ox + (side === "EAST" ? p.width : p.width / 2) - 3,
+          y: p.oy + (side === "EAST" ? p.height / 2 : p.height) - 3,
+          width: 6, height: 6, layoutOptions: {"elk.port.side": side}});
+      }
+      return {id: n.id, width: n.width, height: n.height * (slots.length ? 2 : 1), ports, parts};
+    });
     const edges = [];
     for (const use of snap.nodes) {
       for (const e of use.edges) {
         if (!e.def) continue;
+        if (byId.get(use.id).par && e.idx === 0 && e.def === use.proj.par) continue;
         const id = "e" + use.id + "i" + e.idx;
         const reg = byId.get(use.edges[0]?.def)?.n;
         const back = e.idx === 2 && (use.kind === "LOOP" ||
           (use.kind === "PHI" && reg?.kind === "LOOP"));
         edges.push({id, use: use.id, def: e.def, idx: e.idx, role: e.role, label: e.label,
+          bind: use.kind === "SCOPE",
           // Layout follows value/control flow downward. SVG arrows point back
           // from use to def, matching Simple's actual edge direction.
           sources: ["n" + e.def + "o"], targets: ["n" + use.id + "i" + e.idx],
@@ -43,31 +106,83 @@ class GraphLayout {
       }
     }
     const graph = await this.elk.layout({
-      id: "root", children: nodes.map(({n, label, type, ...box}) => box),
+      id: "root", children: groups.filter(g => !g.parts[0].scope).map(({parts, ...box}) => ({...box,
+        layoutOptions: {"elk.portConstraints": "FIXED_POS",
+          // Keep a projection with its parent even when that parent has real uses.
+          "elk.layered.layering.layerConstraint": parts.length === 1 && parts[0].held ? "LAST_SEPARATE" : "NONE"}
+      })),
       // Scope bindings and lifetime associations must not impose CFG ranks.
-      edges: edges.filter(e => e.role !== "ASSOC").map(e => ({
+      edges: edges.filter(e => e.role !== "ASSOC" && !e.bind && !byId.get(e.def).scope).map(e => ({
         id: e.id, sources: e.sources, targets: e.targets, layoutOptions: e.layoutOptions
       })),
       layoutOptions: {
         "elk.algorithm": "layered", "elk.direction": "DOWN", "elk.edgeRouting": "ORTHOGONAL",
         "elk.spacing.nodeNode": 32, "elk.layered.spacing.nodeNodeBetweenLayers": 48,
         "elk.padding": "[top=24,left=24,bottom=24,right=24]",
+        "elk.separateConnectedComponents": held.length === 0,
         "elk.layered.considerModelOrder.strategy": "NODES_AND_EDGES",
         "elk.randomSeed": 1
       }
     });
+    // Scope ports use the same local geometry; place their boxes after CFG nodes.
+    for (const g of groups.filter(g => g.parts[0].scope)) graph.children.push({...g, x: 0, y: 0});
     const boxes = new Map(graph.children.map(n => [n.id, n]));
-    const routes = new Map(graph.edges.map(e => [e.id, e]));
-    for (const n of nodes) {
-      const box = boxes.get(n.id);
-      n.x = box.x; n.y = box.y;
-      // Keep ports in input-slot order even if ELK reorders its result.
+    const routes = new Map((graph.edges || []).map(e => [e.id, e]));
+    for (const group of groups) {
+      const box = boxes.get(group.id);
       const ports = new Map(box.ports.map(p => [p.id, p]));
-      n.ports = n.ports.map(p => ports.get(p.id));
+      for (const n of group.parts) {
+        n.x = box.x + n.ox; n.y = box.y + n.oy;
+        // Keep semantic nodes/slots intact for selection and neighborhood marks.
+        n.ports = n.n.edges.map(e => {
+          const p = ports.get(n.id + "i" + e.idx);
+          return p && {...p, x: p.x - n.ox, y: p.y - n.oy, edge: e};
+        }).filter(Boolean);
+        const out = ports.get(n.id + "o");
+        n.ports.push({...out, x: out.x - n.ox, y: out.y - n.oy});
+      }
+    }
+    // Saved scopes describe suspended parser states at their control points.
+    // Keep a common column, nudging down only when two name tables overlap.
+    const ctrlY = n => {
+      const ctrl = byId.get(n.n.edges.find(e => e.label === "$ctrl" || e.idx === 0)?.def);
+      return ctrl ? ctrl.y + ctrl.height + 24 : 24;
+    };
+    const saved = scopes.filter(n => n !== active).sort((a, b) => ctrlY(a) - ctrlY(b) || a.n.id - b.n.id);
+    if (saved.length) {
+      const x = graph.width + 48;
+      let y = 24;
+      for (const n of saved) {
+        n.x = x;
+        n.y = Math.max(y, ctrlY(n));
+        y = n.y + n.height + 24;
+      }
+      graph.width = x + Math.max(...saved.map(n => n.width)) + 24;
+      graph.height = Math.max(graph.height, y);
+    }
+    // The active scope moves with the parser, below the current graph.
+    if (active) {
+      graph.width = Math.max(graph.width, active.width + 48);
+      active.x = (graph.width - active.width) / 2;
+      active.y = graph.height + 24;
+      graph.height = active.y + active.height + 24;
+    }
+    // Parser ownership is an overlay, never an IR node or an ELK flow edge.
+    const parser = owned.length ? {width: Math.max(180, (owned.length + 1) * 18), height: 36} : null;
+    if (parser) {
+      graph.width = Math.max(graph.width, parser.width + 48);
+      parser.x = (graph.width - parser.width) / 2;
+      parser.y = graph.height + 24;
+      graph.height = parser.y + parser.height + 24;
+      owned.sort((a, b) => a.x - b.x || a.n.id - b.n.id);
+      parser.ports = owned.map((n, i) => ({id: "parser-i" + n.n.id,
+        x: parser.width * (i + 1) / (owned.length + 1) - 3, y: -3}));
+      for (const n of owned) edges.push({id: "parser-hold-" + n.n.id, scope: n.scope, active: n === active,
+        use: 0, def: n.n.id, role: "PARSER", sources: [n.id + "o"], targets: ["parser-i" + n.n.id]});
     }
     for (const e of edges) {
-      if (e.role === "ASSOC") {
-        const def = byId.get(e.def), use = byId.get(e.use);
+      if (e.role === "ASSOC" || e.role === "PARSER" || e.bind || byId.get(e.def).scope) {
+        const def = byId.get(e.def), use = e.role === "PARSER" ? parser : byId.get(e.use);
         const a = def.ports.find(p => p.id === e.sources[0]);
         const b = use.ports.find(p => p.id === e.targets[0]);
         const x = def.x + a.x + 3, y = def.y + a.y + 3;
@@ -79,6 +194,8 @@ class GraphLayout {
             .map((p, i) => `${i ? "L" : "M"}${p.x},${p.y}`).join(" ")).join(" ");
       }
     }
-    return {width: graph.width, height: graph.height, nodes, edges};
+    return {width: graph.width, height: graph.height, nodes, edges,
+      parser, scope: active?.n.id || 0, scopes: new Set(owned.filter(n => n.scope).map(n => n.n.id)),
+      held: new Set(held.map(n => n.n.id))};
   }
 }
diff --git a/graph/web/render.js b/graph/web/render.js
index 76cf8c06..34c66a02 100644
--- a/graph/web/render.js
+++ b/graph/web/render.js
@@ -6,7 +6,7 @@ class GraphView {
     this.pick = 0;
     this.auto = true;
     this.scene = null;
-    this.colors = {CTRL: "#b63838", DATA: "#536477", MEM: "#2867b2", ASSOC: "#9396a3"};
+    this.colors = {CTRL: "#b63838", DATA: "#536477", MEM: "#2867b2", ASSOC: "#9396a3", PARSER: "#7956a5"};
     this.svg = d3.select(host).append("svg").attr("aria-label", "Compiler graph");
     const defs = this.svg.append("defs");
     for (const [role, color] of Object.entries(this.colors)) {
@@ -17,6 +17,7 @@ class GraphView {
     }
     this.world = this.svg.append("g");
     this.links = this.world.append("g").attr("class", "edges");
+    this.parser = this.world.append("g").attr("class", "parser");
     this.nodes = this.world.append("g").attr("class", "nodes");
     this.zoom = d3.zoom().scaleExtent([.02, 4]).on("zoom", event => {
       if (event.sourceEvent) this.auto = false;
@@ -46,11 +47,24 @@ class GraphView {
       .attr("marker-start", e => "url(#arrow-" + e.role + ")")
       .each(function(e) {
         d3.select(this).selectAll("title").data([e]).join("title")
-          .text(`#${e.use}[${e.idx}] → #${e.def} · ${e.role}${e.label ? " · " + e.label : ""}`);
+          .text(e.role === "PARSER" ? (e.scope ? `Parser holds ${e.active ? "active" : "saved"} scope #${e.def}` :
+            `Parser holds #${e.def}; no graph users yet`) :
+            `#${e.use}[${e.idx}] → #${e.def} · ${e.role}${e.label ? " · " + e.label : ""}`);
+      });
+    this.parser.selectAll("g").data(scene.parser ? [scene.parser] : []).join(enter => {
+      const g = enter.append("g");
+      g.append("rect").attr("rx", 6);
+      g.append("text").attr("class", "label").attr("text-anchor", "middle").attr("y", 22).text("Parser");
+      g.append("title").text("Display-only references to parser scopes and unfinished values; these are not compiler edges.");
+      return g;
+    }).attr("transform", p => `translate(${p.x},${p.y})`)
+      .each(function(p) {
+        d3.select(this).select("rect").attr("width", p.width).attr("height", p.height);
+        d3.select(this).selectAll("text").attr("x", p.width / 2);
       });
     const boxes = this.nodes.selectAll("g.node").data(scene.nodes, n => n.id).join(enter => {
       const g = enter.append("g").attr("class", "node");
-      g.append("rect").attr("class", "box");
+      g.append("path").attr("class", "box");
       g.append("text").attr("class", "head").attr("x", 8).attr("y", 15);
       g.append("text").attr("class", "label").attr("text-anchor", "middle").attr("y", 33);
       g.append("text").attr("class", "type").attr("text-anchor", "middle").attr("y", 51);
@@ -58,25 +72,34 @@ class GraphView {
       return g;
     });
     boxes.attr("id", n => n.id).attr("data-id", n => n.n.id)
+      .classed("held", n => !!n.held)
       .attr("transform", n => `translate(${n.x},${n.y})`)
       .on("click", (event, n) => { event.stopPropagation(); this.select(n.n.id); });
-    boxes.select("rect.box").attr("width", n => n.width).attr("height", n => n.height)
-      .attr("rx", n => ["CTRL", "REGION", "LOOP", "FUN", "UNIT"].includes(n.n.kind) ? 3 : 14)
+    boxes.select("path.box").attr("d", n => this.shape(n))
       .attr("fill", n => ({CTRL: "#fff1c4", REGION: "#fff1c4", LOOP: "#ffe0ab", FUN: "#ffe0ab",
         UNIT: "#ffe0ab", MEM: "#dcecff", PHI: "#f5e4fa", SCOPE: "#e5e0ff", DATA: "#edf3f7"})[n.n.kind]);
-    boxes.select("text.head").text(n => `#${n.n.id} · ${n.n.kind}${n.n.proj ? " · p" + n.n.proj.idx : ""}`);
-    boxes.select("text.label").attr("x", n => n.width / 2).text(n => n.label);
-    boxes.select("text.type").attr("x", n => n.width / 2).text(n => n.type);
+    boxes.select("text.head").attr("y", n => n.scope ? 47 : 15)
+      .text(n => `#${n.n.id}${n.n.proj ? " · p" + n.n.proj.idx : ""}`);
+    boxes.select("text.label").attr("x", n => n.width / 2).attr("y", n => n.scope ? 51 : 33)
+      .text(n => n.label);
+    boxes.select("text.type").attr("x", n => n.width / 2).text(n => n.scope ? "" : n.type);
     boxes.select("title").text(n => this.info(n.n));
     boxes.each((n, i, groups) => {
       const ports = n.ports.filter(p => p.id !== n.id + "o");
       const group = d3.select(groups[i]);
+      group.selectAll("line.row").data(n.scope ? ports : [], p => p.id).join("line")
+        .attr("class", "row").attr("x1", (p, i) => i ? p.x + 3 - p.span / 2 : 0)
+        .attr("x2", (p, i) => i ? p.x + 3 - p.span / 2 : n.width)
+        .attr("y1", (p, i) => i ? 0 : 30).attr("y2", 30);
+      group.selectAll("text.bind").data(n.scope ? ports : [], p => p.id).join("text")
+        .attr("class", "bind").attr("x", p => p.x + 3).attr("y", 20).attr("text-anchor", "middle")
+        .text(p => p.edge.label || "[" + p.edge.idx + "]");
       group.selectAll("circle.port").data(ports, p => p.id).join("circle")
         .attr("class", "port").attr("cx", p => p.x + 3).attr("cy", p => p.y + 3)
-        .attr("r", 3).attr("fill", (p, j) => n.n.edges[j].def ? "#536477" : "white");
+        .attr("r", 3).attr("fill", p => p.edge.def ? "#536477" : "white");
       group.selectAll("text.slot").data(ports, p => p.id).join("text")
         .attr("class", "slot").attr("x", p => p.x + 3).attr("y", p => p.y - 4)
-        .attr("text-anchor", "middle").text((p, j) => n.n.edges[j].idx);
+        .attr("text-anchor", "middle").text(p => p.edge.idx);
     });
     this.assocs(document.getElementById("assocs").checked);
     this.mark();
@@ -84,8 +107,23 @@ class GraphView {
     if (this.auto) this.fit();
   }
 
+  shape(n) {
+    const w = n.width, h = n.height;
+    // A MultiNode and its projection cells tile one rectangular box.
+    if (n.cell || n.n.kind === "CTRL" || n.n.kind === "UNIT") return `M0,0H${w}V${h}H0Z`;
+    if (n.n.kind === "REGION") return `M12,0H${w - 12}L${w},${h}H0Z`;
+    if (n.n.kind === "PHI") return `M12,0H${w - 12}L${w},${h / 2}L${w - 12},${h}H12L0,${h / 2}Z`;
+    if (n.n.kind === "MEM" || n.n.kind === "FUN")
+      return `M10,0H${w - 10}L${w},10V${h - 10}L${w - 10},${h}H10L0,${h - 10}V10Z`;
+    const r = n.n.kind === "LOOP" ? 24 : n.n.kind === "SCOPE" ? 4 : 14;
+    return `M${r},0H${w - r}Q${w},0 ${w},${r}V${h - r}Q${w},${h} ${w - r},${h}` +
+      `H${r}Q0,${h} 0,${h - r}V${r}Q0,0 ${r},0Z`;
+  }
+
   info(n) {
-    return `#${n.id} ${n.label}\n${n.kind}${n.proj ? " · projection " + n.proj.idx + " of #" + n.proj.par : ""}` +
+    return `#${n.id} ${n.label}${n.proj ? "\nProjection " + n.proj.idx + " of #" + n.proj.par : ""}` +
+      (this.scene.held.has(n.id) ? "\nHeld by parser; no graph users yet" : "") +
+      (this.scene.scopes.has(n.id) ? (this.scene.scope === n.id ? "\nActive parser scope" : "\nSaved parser scope") : "") +
       `\n${n.type || "Type not computed"}\n\n` + n.edges.map(e =>
         `[${e.idx}] → ${e.def ? "#" + e.def : "—"}  ${e.role}${e.label ? "  " + e.label : ""}`).join("\n");
   }
@@ -94,13 +132,13 @@ class GraphView {
     this.pick = id;
     const node = this.scene?.nodes.find(n => n.n.id === id);
     this.nodes.selectAll("g.node").classed("selected", n => n.n.id === id);
-    this.links.selectAll("path.edge").classed("selected", e => e.use === id || e.def === id);
+    this.links.selectAll("path.edge").classed("selected", e => id !== 0 && (e.use === id || e.def === id));
     const detail = document.getElementById("detail");
     detail.hidden = !id;
     detail.textContent = node ? this.info(node.n) : `#${id} is absent in this frame.`;
   }
 
-  assocs(show) { this.links.selectAll(".ASSOC").style("display", show ? null : "none"); }
+  assocs(show) { this.links.selectAll(".ASSOC").style("display", e => show || e.bind ? null : "none"); }
 
   mark() {
     const evt = this.evt;
diff --git a/graph/web/viewer.js b/graph/web/viewer.js
index c36c369c..63ee195e 100644
--- a/graph/web/viewer.js
+++ b/graph/web/viewer.js
@@ -81,11 +81,17 @@ async function render(index) {
   const frame = frames[index];
   busy = !frame.layout ? "Laying out frame " + (index + 1) + "..." : "Drawing...";
   updateUI();
-  if (frame.pos >= 0) program.setSelectionRange(frame.pos, frame.pos + 1);
   try {
     if (!layout) layout = new GraphLayout();
-    if (!frame.layout) frame.layout = await layout.run(frame.snap);
-    if (generation === frameGeneration) renderer.show(frame.snap, frame.layout, frame.evt);
+    if (!frame.layout) frame.layout = await layout.run(frame.snap, frame.evt);
+    if (generation === frameGeneration) {
+      renderer.show(frame.snap, frame.layout, frame.evt);
+      if (frame.pos >= 0) {
+        // Stepping focuses a button; focus the source so its selection is visible.
+        program.focus({preventScroll: true});
+        program.setSelectionRange(frame.pos, frame.pos + 1);
+      }
+    }
     rendering = false;
     busy = "";
     if (generation === frameGeneration) current = index;