René's URL Explorer Experiment

{"@context":"https://schema.org","@type":"DiscussionForumPosting","headline":"Autogenerated documentation: using LSP make call hierarchy graphs","articleBody":"## Motivation\n\nAutomatically extract important use case call graphs from code to explain high-level flow of the program, perhaps bake that into autogenerated documentation.\n\n## Implementation\n\nOptions:\n\n### Build on top of LSP\n\nPro: lots of languages have LSP so we can build on top of giants.\n\n```go\npackage main\n\nimport (\n\t\"context\"\n\t\"encoding/json\"\n\t\"errors\"\n\t\"fmt\"\n\t\"io\"\n\t\"log\"\n\t\"log/slog\"\n\t\"os/exec\"\n\n\t\"github.com/sourcegraph/jsonrpc2\"\n\tlsp \"github.com/toitware/go-lsp\"\n\t\"github.com/toitware/go-lsp/lspext\"\n)\n\n// https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification/\n\ntype CallHierarchyItem struct {\n\tName           string          `json:\"name\"`\n\tKind           int             `json:\"kind\"`\n\tTags           []int           `json:\"tags,omitempty\"`\n\tDetail         string          `json:\"detail,omitempty\"`\n\tURI            lsp.DocumentURI `json:\"uri\"`\n\tRange          lsp.Range       `json:\"range\"`\n\tSelectionRange lsp.Range       `json:\"selectionRange\"`\n\tData           interface{}     `json:\"data,omitempty\"`\n}\n\ntype CallHierarchyPrepareParams struct {\n\tlsp.TextDocumentPositionParams\n\n\tWorkDoneToken interface{} `json:\"workDoneToken,omitempty\"`\n}\n\ntype CallHierarchyIncomingCall struct {\n\tFrom       CallHierarchyItem `json:\"from\"`\n\tFromRanges []lsp.Range       `json:\"fromRanges\"`\n}\n\ntype CallHierarchyOutgoingCall struct {\n\tTo         CallHierarchyItem `json:\"to\"`\n\tFromRanges []lsp.Range       `json:\"fromRanges\"`\n}\n\n// Minimal stream wrapper for jsonrpc2\ntype stdioStream struct {\n\tio.Reader\n\tio.Writer\n\tio.Closer\n}\n\nvar _ interface {\n\tio.Reader\n\tio.Writer\n\tio.Closer\n} = (*stdioStream)(nil)\n\nfunc hailait() {\n\tctx := context.Background()\n\n\t// Start gopls in stdio mode\n\tcmd := exec.Command(\"bob\", \"tools\", \"langserver\")\n\tstdin, _ := cmd.StdinPipe()\n\tstdout, _ := cmd.StdoutPipe()\n\tcmd.Stderr = cmd.Stdout\n\n\tif err := cmd.Start(); err != nil {\n\t\tlog.Fatal(\"failed to start gopls:\", err)\n\t}\n\n\tstream := jsonrpc2.NewBufferedStream(\u0026stdioStream{stdout, stdin, stdin}, jsonrpc2.VSCodeObjectCodec{})\n\tconn := jsonrpc2.NewConn(ctx, stream, jsonrpc2.HandlerWithError(func(ctx context.Context, c *jsonrpc2.Conn, r *jsonrpc2.Request) (result interface{}, err error) {\n\t\tswitch r.Method {\n\t\tcase \"window/showMessage\":\n\t\t\tlogMessageParams := struct {\n\t\t\t\tMessage string `json:\"message\"`\n\t\t\t\tType    int    `json:\"type\"`\n\t\t\t}{}\n\t\t\tif err := json.Unmarshal(*r.Params, \u0026logMessageParams); err != nil {\n\t\t\t\tpanic(err)\n\t\t\t}\n\t\t\tslog.Info(\"LSP server\", \"kind\", \"show\", \"msg\", logMessageParams.Message, \"type\", logMessageParams.Type)\n\t\t\treturn nil, nil\n\t\tcase \"window/logMessage\":\n\t\t\tlogMessageParams := struct {\n\t\t\t\tMessage string `json:\"message\"`\n\t\t\t\tType    int    `json:\"type\"`\n\t\t\t}{}\n\t\t\tif err := json.Unmarshal(*r.Params, \u0026logMessageParams); err != nil {\n\t\t\t\tpanic(err)\n\t\t\t}\n\t\t\tslog.Info(\"LSP server\", \"kind\", \"log\", \"msg\", logMessageParams.Message, \"type\", logMessageParams.Type)\n\t\t\treturn nil, nil\n\t\tdefault:\n\t\t\tslog.Warn(\"returning error\", \"request\", r.Method, \"params\", string(*r.Params))\n\t\t\treturn nil, errors.New(\"requests not implemented\")\n\t\t}\n\t}))\n\tdefer stream.Close()\n\n\t// ---- Initialize ----\n\tinitReq := lsp.InitializeParams{\n\t\tRootURI: \"file:///workspace\",\n\t}\n\n\tvar initResp lsp.InitializeResult\n\tif err := conn.Call(ctx, \"initialize\", initReq, \u0026initResp); err != nil {\n\t\tlog.Fatal(\"initialize error:\", err)\n\t}\n\n\t// Tell server we're ready\n\t_ = conn.Notify(ctx, \"initialized\", struct{}{})\n\n\t// --- Prepare call hierarchy ---\n\tparams := CallHierarchyPrepareParams{\n\t\tTextDocumentPositionParams: lsp.TextDocumentPositionParams{\n\t\t\tTextDocument: lsp.TextDocumentIdentifier{\n\t\t\t\tURI: initReq.RootURI + \"/pkg/mypkg/example.go\",\n\t\t\t},\n\t\t\tPosition: lsp.Position{ // -1 because positions are 0-based\n\t\t\t\tLine:      114 - 1,\n\t\t\t\tCharacter: 6 - 1,\n\t\t\t},\n\t\t},\n\t}\n\n\tvar items []CallHierarchyItem\n\tif err := conn.Call(ctx, \"textDocument/prepareCallHierarchy\", params, \u0026items); err != nil {\n\t\tlog.Fatal(\"prepareCallHierarchy:\", err)\n\t}\n\n\tif len(items) == 0 {\n\t\tlog.Println(\"No call hierarchy items found at location\")\n\t\treturn\n\t}\n\n\titem := items[0]\n\tfmt.Println(\"Item:\", item.Name)\n\n\t_ = lspext.CacheSetParams{}\n\t// --- Incoming calls ---\n\tvar incoming []CallHierarchyIncomingCall\n\tif err := conn.Call(ctx, \"callHierarchy/incomingCalls\", struct {\n\t\tItem CallHierarchyItem `json:\"item\"`\n\t}{item}, \u0026incoming); err != nil {\n\t\tlog.Fatal(\"incomingCalls: \", err)\n\t}\n\n\tfmt.Println(\"\\nIncoming calls:\")\n\tfor _, c := range incoming {\n\t\tfmt.Println(\"   from:\", c.From.Name)\n\t}\n\n\t// --- Outgoing calls ---\n\t// var outgoing []CallHierarchyOutgoingCall\n\t// if err := conn.Call(ctx, \"callHierarchy/outgoingCalls\", item, \u0026outgoing); err != nil {\n\t// \tlog.Fatal(\"outgoingCalls:\", err)\n\t// }\n\n\t// fmt.Println(\"\\nOutgoing calls:\")\n\t// for _, c := range outgoing {\n\t// \tfmt.Println(\"   to:\", c.To.Name)\n\t// }\n}\n```\n\n`go.mod`:\n\n```\n\tgithub.com/sourcegraph/jsonrpc2 v0.2.1 // indirect\n\tgithub.com/toitware/go-lsp v0.0.0-20240220075859-6b0ca01316f0 // indirect\n```\n\n### SCIP\n\nNot popular implementation, backed by one company with unclear investment on it: https://sourcegraph.com/blog/the-future-of-scip","author":{"url":"https://github.com/joonas-fi","@type":"Person","name":"joonas-fi"},"datePublished":"2025-11-18T10:13:38.000Z","interactionStatistic":{"@type":"InteractionCounter","interactionType":"https://schema.org/CommentAction","userInteractionCount":0},"url":"https://github.com/71/turbobob/issues/71"}