1 files changed, 142 insertions, 0 deletions
diff --git a/gopls/internal/lsp/cmd/call_hierarchy.go b/gopls/internal/lsp/cmd/call_hierarchy.go
new file mode 100644
index 000000000..eb5d29de8
--- /dev/null
+++ b/gopls/internal/lsp/cmd/call_hierarchy.go
@@ -0,0 +1,142 @@
+// Copyright 2020 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package cmd
+
+import (
+	"context"
+	"flag"
+	"fmt"
+	"strings"
+
+	"golang.org/x/tools/gopls/internal/lsp/protocol"
+	"golang.org/x/tools/gopls/internal/span"
+	"golang.org/x/tools/internal/tool"
+)
+
+// callHierarchy implements the callHierarchy verb for gopls.
+type callHierarchy struct {
+	app *Application
+}
+
+func (c *callHierarchy) Name() string      { return "call_hierarchy" }
+func (c *callHierarchy) Parent() string    { return c.app.Name() }
+func (c *callHierarchy) Usage() string     { return "<position>" }
+func (c *callHierarchy) ShortHelp() string { return "display selected identifier's call hierarchy" }
+func (c *callHierarchy) DetailedHelp(f *flag.FlagSet) {
+	fmt.Fprint(f.Output(), `
+Example:
+
+	$ # 1-indexed location (:line:column or :#offset) of the target identifier
+	$ gopls call_hierarchy helper/helper.go:8:6
+	$ gopls call_hierarchy helper/helper.go:#53
+`)
+	printFlagDefaults(f)
+}
+
+func (c *callHierarchy) Run(ctx context.Context, args ...string) error {
+	if len(args) != 1 {
+		return tool.CommandLineErrorf("call_hierarchy expects 1 argument (position)")
+	}
+
+	conn, err := c.app.connect(ctx)
+	if err != nil {
+		return err
+	}
+	defer conn.terminate(ctx)
+
+	from := span.Parse(args[0])
+	file := conn.openFile(ctx, from.URI())
+	if file.err != nil {
+		return file.err
+	}
+
+	loc, err := file.mapper.SpanLocation(from)
+	if err != nil {
+		return err
+	}
+
+	p := protocol.CallHierarchyPrepareParams{
+		TextDocumentPositionParams: protocol.LocationTextDocumentPositionParams(loc),
+	}
+
+	callItems, err := conn.PrepareCallHierarchy(ctx, &p)
+	if err != nil {
+		return err
+	}
+	if len(callItems) == 0 {
+		return fmt.Errorf("function declaration identifier not found at %v", args[0])
+	}
+
+	for _, item := range callItems {
+		incomingCalls, err := conn.IncomingCalls(ctx, &protocol.CallHierarchyIncomingCallsParams{Item: item})
+		if err != nil {
+			return err
+		}
+		for i, call := range incomingCalls {
+			// From the spec: CallHierarchyIncomingCall.FromRanges is relative to
+			// the caller denoted by CallHierarchyIncomingCall.from.
+			printString, err := callItemPrintString(ctx, conn, call.From, call.From.URI, call.FromRanges)
+			if err != nil {
+				return err
+			}
+			fmt.Printf("caller[%d]: %s\n", i, printString)
+		}
+
+		printString, err := callItemPrintString(ctx, conn, item, "", nil)
+		if err != nil {
+			return err
+		}
+		fmt.Printf("identifier: %s\n", printString)
+
+		outgoingCalls, err := conn.OutgoingCalls(ctx, &protocol.CallHierarchyOutgoingCallsParams{Item: item})
+		if err != nil {
+			return err
+		}
+		for i, call := range outgoingCalls {
+			// From the spec: CallHierarchyOutgoingCall.FromRanges is the range
+			// relative to the caller, e.g the item passed to
+			printString, err := callItemPrintString(ctx, conn, call.To, item.URI, call.FromRanges)
+			if err != nil {
+				return err
+			}
+			fmt.Printf("callee[%d]: %s\n", i, printString)
+		}
+	}
+
+	return nil
+}
+
+// callItemPrintString returns a protocol.CallHierarchyItem object represented as a string.
+// item and call ranges (protocol.Range) are converted to user friendly spans (1-indexed).
+func callItemPrintString(ctx context.Context, conn *connection, item protocol.CallHierarchyItem, callsURI protocol.DocumentURI, calls []protocol.Range) (string, error) {
+	itemFile := conn.openFile(ctx, item.URI.SpanURI())
+	if itemFile.err != nil {
+		return "", itemFile.err
+	}
+	itemSpan, err := itemFile.mapper.LocationSpan(protocol.Location{URI: item.URI, Range: item.Range})
+	if err != nil {
+		return "", err
+	}
+
+	callsFile := conn.openFile(ctx, callsURI.SpanURI())
+	if callsURI != "" && callsFile.err != nil {
+		return "", callsFile.err
+	}
+	var callRanges []string
+	for _, rng := range calls {
+		call, err := callsFile.mapper.RangeSpan(rng)
+		if err != nil {
+			return "", err
+		}
+		callRange := fmt.Sprintf("%d:%d-%d", call.Start().Line(), call.Start().Column(), call.End().Column())
+		callRanges = append(callRanges, callRange)
+	}
+
+	printString := fmt.Sprintf("function %s in %v", item.Name, itemSpan)
+	if len(calls) > 0 {
+		printString = fmt.Sprintf("ranges %s in %s from/to %s", strings.Join(callRanges, ", "), callsURI.SpanURI().Filename(), printString)
+	}
+	return printString, nil
+}