Hover LSP wiring

lang/src/arr/compiler/query.arr

@@ -149,6 +149,32 @@ fun jump-to-def(cache-manager, uri :: String, line :: Number, col :: Number) ->
   end
 end
 
+# this is a lot like jump-to-def
+type HoverResult = { name :: String, docstring :: String, ann :: A.Ann }
+
+fun hover(cache-manager, uri :: String, line :: Number, col :: Number) -> E.Either<String, HoverResult>:
+  cases(Option) cache-manager.get-surface-ast(uri):
+    | none => E.left("AST not available")
+    | some(ast) =>
+      cases(Option) cache-manager.get-named-result(uri):
+        | none => E.left("Resolved AST not available")
+        | some(named-result) =>
+          cases(Option) find-name-at(ast, line, col):
+            | none => E.left("Did not select a name")
+            | some(name) =>
+              cases(Option) find-name-key-by-srcloc(named-result.ast, name.l):
+                | none => E.left("Post-resolution name not found")
+                | some(key) =>
+                  cases(Option) named-result.env.bindings.get-now(key):
+                    | none => E.left("No value identifier binding found")
+                    | some(vb) => E.right({ name: name.toname(), docstring: vb.doc, ann: vb.ann })
+                  end
+              end
+          end
+      end
+  end
+end
+
 fun document-symbols(cache-manager, uri :: String)
   -> E.Either<String, List<{String; String; S.Srcloc}>>:
   cases(Option) cache-manager.get-named-result(uri):

lang/src/arr/compiler/server.arr

@@ -13,6 +13,7 @@ import js-file("server") as S
 import file("./cli-module-loader.arr") as CLI
 import file("./compile-structs.arr") as CS
 import file("./compile-lib.arr") as CL
+import ast as A
 import file("./query.arr") as Q
 import file("locators/builtin.arr") as B
 
@@ -166,6 +167,10 @@ fun on-query(pyret-dir, cache-manager, query, compile-opts, query-opts, send-mes
         line = query-opts.get-value("line")
         col = query-opts.get-value("col")
         Q.jump-to-def(cache-manager, base-uri, line, col)
+      | query == "hover" then:
+        line = query-opts.get-value("line")
+        col = query-opts.get-value("col")
+        Q.hover(cache-manager, base-uri, line, col)
       | query == "document-symbols" then:
         Q.document-symbols(cache-manager, base-uri)
       | query == "check" then:
@@ -218,6 +223,26 @@ fun on-query(pyret-dir, cache-manager, query, compile-opts, query-opts, send-mes
               ]
               send-message(J.j-obj(d).serialize())
           end
+        | query == "hover" then:
+          cases(E.Either) info-result block:
+            | left(error-str) =>
+              err("hover: no result (errors: " + error-str + ")\n")
+              d = [SD.string-dict: "type", J.j-str("hover-failure")]
+              send-message(J.j-obj(d).serialize())
+            | right(hover-info) =>
+              ann-json = if A.is-a-blank(hover-info.ann):
+                J.j-null
+              else:
+                J.j-str(hover-info.ann.tosource().pretty(40).join-str("\n"))
+              end
+              d = [SD.string-dict:
+                "type", J.j-str("hover-success"),
+                "name", J.j-str(hover-info.name),
+                "ann", ann-json,
+                "doc", J.j-str(hover-info.docstring),
+              ]
+              send-message(J.j-obj(d).serialize())
+          end
         | query == "document-symbols" then:
           cases(E.Either) info-result block:
             | left(error-str) =>

lang/src/arr/trove/ast.arr

@@ -1055,6 +1055,7 @@ data Expr:
     method tosource(self): PP.str("!") + self.id.tosource() end
   | s-id-letrec(l :: Loc, id :: Name, safe :: Boolean) with:
     method label(self): "s-id-letrec" end,
+    # This is not actually to-source! There is a difference between tosource and pretty-print
     method tosource(self): PP.str("~") + self.id.tosource() end
   | s-id-var-modref(l :: Loc, id :: Name, uri :: String, name :: String) with:
     method label(self): "s-id-var-modref" end,

lsp/src/server-node-tmp.ts

@@ -113,6 +113,7 @@ connection.onInitialize(async (_params) => {
   const capabilities: ServerCapabilities = {
     textDocumentSync: TextDocumentSyncKind.Incremental,
     definitionProvider: true,
+    hoverProvider: true,
     documentSymbolProvider: true,
     diagnosticProvider: {
       interFileDependencies: false,
@@ -312,6 +313,8 @@ function sendCheckRequest(
 }
 
 // #region LSP request handlers
+// TODO: there is a lot of redundancy here, we should probably develop better
+// abstractions here! especially for the off-by-one location issues (hacked in rn)
 
 connection.onDocumentSymbol(async (params) => {
   const portFile = getSocketPath();
@@ -365,6 +368,7 @@ connection.onDefinition(async (params) => {
   }
 
   // LSP positions are 0-indexed; Pyret srclocs are 1-indexed
+  // TODO: fix these awful off-by-one errors!
   const line = params.position.line + 1;
   const col = params.position.character + 1;
   const filePath = uriToFilePath(params.textDocument.uri);
@@ -386,6 +390,65 @@ connection.onDefinition(async (params) => {
   }
 });
 
+interface HoverResult {
+  name: string;
+  ann: string;
+  doc: string;
+}
+
+function parseHover(msg: any): HoverResult | null {
+  if (msg.type === "hover-success") {
+    return { name: msg.name, ann: msg.ann, doc: msg.doc };
+  }
+  return null;
+}
+
+connection.onHover(async (params) => {
+  const portFile = getSocketPath();
+  if (!fs.existsSync(portFile)) {
+    connection.console.error("Pyret server not running, cannot get hover info");
+    return null;
+  }
+
+  const line = params.position.line + 1;
+  const col = params.position.character + 1;
+  const filePath = uriToFilePath(params.textDocument.uri);
+
+  try {
+    const result = await sendQueryRequest(
+      portFile,
+      "hover",
+      filePath,
+      { line, col },
+      parseHover,
+    );
+    if (!result) return null;
+
+    const parts: string[] = [];
+    if (result.ann) {
+      parts.push(`\`\`\`pyret\n${result.name} :: ${result.ann}\n\`\`\``);
+    }
+    if (result.doc) {
+      if (result.ann) {
+        parts.push(result.doc);
+      } else {
+        parts.push(`${result.name}: ${result.doc}`);
+      }
+    }
+    if (parts.length === 0) return null;
+
+    return {
+      contents: {
+        kind: "markdown",
+        value: parts.join("\n\n"),
+      },
+    };
+  } catch (err) {
+    connection.console.error(`hover error: ${err}`);
+    return null;
+  }
+});
+
 const documents = new TextDocuments(TextDocument);
 
 // Track the document version at last save per URI. VS Code triggers

vscode/sampleFiles/lsp/hover.arr

@@ -10,6 +10,13 @@ end
 
 not-zero
 
+fun doc-no-ann(asd):
+  doc: "hi mom"
+  asd
+end
+
+doc-no-ann
+
 div-refine :: Number, Number%(not-zero) -> Number
 fun div-refine(num, den):
   doc: "divides the things"