textDocument/completion support via gocode

langserver/completion.go

@@ -0,0 +1,79 @@
+package langserver
+
+import (
+	"context"
+	"fmt"
+
+	"github.com/sourcegraph/go-langserver/langserver/internal/gocode"
+	"github.com/sourcegraph/go-langserver/pkg/lsp"
+	"github.com/sourcegraph/jsonrpc2"
+)
+
+var (
+	GocodeCompletionEnabled = false
+	CIKConstantSupported    = lsp.CIKVariable // or lsp.CIKConstant if client supported
+)
+
+func (h *LangHandler) handleTextDocumentCompletion(ctx context.Context, conn jsonrpc2.JSONRPC2, req *jsonrpc2.Request, params lsp.CompletionParams) (*lsp.CompletionList, error) {
+	if !isFileURI(params.TextDocument.URI) {
+		return nil, &jsonrpc2.Error{
+			Code:    jsonrpc2.CodeInvalidParams,
+			Message: fmt.Sprintf("textDocument/completion not yet supported for out-of-workspace URI (%q)", params.TextDocument.URI),
+		}
+	}
+
+	// In the case of testing, our OS paths and VFS paths do not match. In the
+	// real world, this is never the case. Give the test suite the opportunity
+	// to correct the path now.
+	vfsURI := params.TextDocument.URI
+	if testOSToVFSPath != nil {
+		vfsURI = pathToURI(testOSToVFSPath(uriToFilePath(vfsURI)))
+	}
+
+	// Read file contents and calculate byte offset.
+	contents, err := h.readFile(ctx, vfsURI)
+	if err != nil {
+		return nil, err
+	}
+	filename := h.FilePath(params.TextDocument.URI)
+	offset, valid, why := offsetForPosition(contents, params.Position)
+	if !valid {
+		return nil, fmt.Errorf("invalid position: %s:%d:%d (%s)", filename, params.Position.Line, params.Position.Character, why)
+	}
+
+	ca, rangelen := gocode.AutoComplete(contents, filename, offset)
+	citems := make([]lsp.CompletionItem, len(ca))
+	for i, it := range ca {
+		var kind lsp.CompletionItemKind
+		switch it.Class.String() {
+		case "const":
+			kind = CIKConstantSupported
+		case "func":
+			kind = lsp.CIKFunction
+		case "import":
+			kind = lsp.CIKModule
+		case "package":
+			kind = lsp.CIKModule
+		case "type":
+			kind = lsp.CIKClass
+		case "var":
+			kind = lsp.CIKVariable
+		}
+		citems[i] = lsp.CompletionItem{
+			Label:  it.Name,
+			Kind:   kind,
+			Detail: it.Type,
+			TextEdit: &lsp.TextEdit{
+				Range: lsp.Range{
+					Start: lsp.Position{Line: params.Position.Line, Character: params.Position.Character - rangelen},
+					End:   lsp.Position{Line: params.Position.Line, Character: params.Position.Character},
+				},
+				NewText: it.Name,
+			},
+		}
+	}
+	return &lsp.CompletionList{
+		IsIncomplete: false,
+		Items:        citems,
+	}, nil
+}

langserver/handler.go

@@ -15,6 +15,7 @@ import (
 	opentracing "github.com/opentracing/opentracing-go"
 	"github.com/opentracing/opentracing-go/ext"
 
+	"github.com/sourcegraph/go-langserver/langserver/internal/gocode"
 	"github.com/sourcegraph/go-langserver/pkg/lsp"
 	"github.com/sourcegraph/go-langserver/pkg/lspext"
 	"github.com/sourcegraph/jsonrpc2"
@@ -72,6 +73,13 @@ type LangHandler struct {
 
 // reset clears all internal state in h.
 func (h *LangHandler) reset(init *InitializeParams) error {
+	for _, k := range init.Capabilities.TextDocument.Completion.CompletionItemKind.ValueSet {
+		if k == lsp.CIKConstant {
+			CIKConstantSupported = lsp.CIKConstant
+			break
+		}
+	}
+
 	if isFileURI(lsp.DocumentURI(init.InitializeParams.RootPath)) {
 		log.Printf("Passing an initialize rootPath URI (%q) is deprecated. Use rootUri instead.", init.InitializeParams.RootPath)
 	}
@@ -189,6 +197,9 @@ func (h *LangHandler) Handle(ctx context.Context, conn jsonrpc2.JSONRPC2, req *j
 		if err := h.reset(&params); err != nil {
 			return nil, err
 		}
+		if GocodeCompletionEnabled {
+			gocode.InitDaemon(h.BuildContext(ctx))
+		}
 
 		// PERF: Kick off a workspace/symbol in the background to warm up the server
 		if yes, _ := strconv.ParseBool(envWarmupOnInitialize); yes {
@@ -203,11 +214,16 @@ func (h *LangHandler) Handle(ctx context.Context, conn jsonrpc2.JSONRPC2, req *j
 		}
 
 		kind := lsp.TDSKIncremental
+		var completionOp *lsp.CompletionOptions
+		if GocodeCompletionEnabled {
+			completionOp = &lsp.CompletionOptions{TriggerCharacters: []string{"."}}
+		}
 		return lsp.InitializeResult{
 			Capabilities: lsp.ServerCapabilities{
 				TextDocumentSync: lsp.TextDocumentSyncOptionsOrKind{
 					Kind: &kind,
 				},
+				CompletionProvider:           completionOp,
 				DefinitionProvider:           true,
 				DocumentFormattingProvider:   true,
 				DocumentSymbolProvider:       true,
@@ -284,6 +300,16 @@ func (h *LangHandler) Handle(ctx context.Context, conn jsonrpc2.JSONRPC2, req *j
 		}
 		return h.handleXDefinition(ctx, conn, req, params)
 
+	case "textDocument/completion":
+		if req.Params == nil {
+			return nil, &jsonrpc2.Error{Code: jsonrpc2.CodeInvalidParams}
+		}
+		var params lsp.CompletionParams
+		if err := json.Unmarshal(*req.Params, &params); err != nil {
+			return nil, err
+		}
+		return h.handleTextDocumentCompletion(ctx, conn, req, params)
+
 	case "textDocument/references":
 		if req.Params == nil {
 			return nil, &jsonrpc2.Error{Code: jsonrpc2.CodeInvalidParams}

langserver/internal/gocode/.gitignore

@@ -0,0 +1,12 @@
+*.8
+*.a
+*.out
+gocode
+gocode.exe
+goremote
+gocodetest
+*.swp
+listidents
+showcursor
+showsmap
+rename

langserver/internal/gocode/LICENSE

@@ -0,0 +1,19 @@
+Copyright (C) 2010 nsf <[email protected]>
+
+Permission is hereby granted, free of charge, to any person obtaining a copy
+of this software and associated documentation files (the "Software"), to deal
+in the Software without restriction, including without limitation the rights
+to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+copies of the Software, and to permit persons to whom the Software is
+furnished to do so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in
+all copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+THE SOFTWARE.