internal/lsp/debug: show Options in gopls debug server

Provide both the current values and default values of Options. These
are in the Sessions tabs.

Display in the debug server, including the Options, needs work.

Change-Id: I970fa65631702b79f6e5f8089a5b1cc5daa8334e
Reviewed-on: https://go-review.googlesource.com/c/tools/+/275540
Trust: Peter Weinberger <pjw@google.com>
Run-TryBot: Peter Weinberger <pjw@google.com>
TryBot-Result: Go Bot <gobot@golang.org>
Reviewed-by: Robert Findley <rfindley@google.com>

Author: pjweinbgo

internal/lsp/debug/info.go

@@ -9,8 +9,12 @@ import (
 	"context"
 	"fmt"
 	"io"
+	"reflect"
 	"runtime/debug"
+	"sort"
 	"strings"
+
+	"golang.org/x/tools/internal/lsp/source"
 )
 
 type PrintMode int
@@ -156,3 +160,97 @@ func printModuleInfo(w io.Writer, m *Module, mode PrintMode) {
 	}
 	fmt.Fprintf(w, "\n")
 }
+
+type field struct {
+	index []int
+}
+
+var fields []field
+
+// find all the options. The presumption is that the Options are nested structs
+// and that pointers don't need to be dereferenced
+func swalk(t reflect.Type, ix []int, indent string) {
+	switch t.Kind() {
+	case reflect.Struct:
+		for i := 0; i < t.NumField(); i++ {
+			fld := t.Field(i)
+			ixx := append(append([]int{}, ix...), i)
+			swalk(fld.Type, ixx, indent+". ")
+		}
+	default:
+		// everything is either a struct or a field (that's an assumption about Options)
+		fields = append(fields, field{ix})
+	}
+}
+
+func showOptions(o *source.Options) []string {
+	// non-breaking spaces for indenting current and defaults when they are on a separate line
+	const indent = "\u00a0\u00a0\u00a0\u00a0\u00a0"
+	var ans strings.Builder
+	t := reflect.TypeOf(*o)
+	swalk(t, []int{}, "")
+	v := reflect.ValueOf(*o)
+	do := reflect.ValueOf(*source.DefaultOptions())
+	for _, f := range fields {
+		val := v.FieldByIndex(f.index)
+		def := do.FieldByIndex(f.index)
+		tx := t.FieldByIndex(f.index)
+		prefix := fmt.Sprintf("%s (type is %s): ", tx.Name, tx.Type)
+		is := strVal(val)
+		was := strVal(def)
+		if len(is) < 30 && len(was) < 30 {
+			fmt.Fprintf(&ans, "%s current:%s, default:%s\n", prefix, is, was)
+		} else {
+			fmt.Fprintf(&ans, "%s\n%scurrent:%s\n%sdefault:%s\n", prefix, indent, is, indent, was)
+		}
+	}
+	return strings.Split(ans.String(), "\n")
+}
+func strVal(val reflect.Value) string {
+	switch val.Kind() {
+	case reflect.Bool:
+		return fmt.Sprintf("%v", val.Interface())
+	case reflect.Int, reflect.Int8, reflect.Int16, reflect.Int32, reflect.Int64:
+		return fmt.Sprintf("%v", val.Interface())
+	case reflect.Uint, reflect.Uint8, reflect.Uint16, reflect.Uint32, reflect.Uint64:
+		return fmt.Sprintf("%v", val.Interface())
+	case reflect.Uintptr, reflect.UnsafePointer:
+		return fmt.Sprintf("0x%x", val.Pointer())
+	case reflect.Complex64, reflect.Complex128:
+		return fmt.Sprintf("%v", val.Complex())
+	case reflect.Array, reflect.Slice:
+		ans := []string{}
+		for i := 0; i < val.Len(); i++ {
+			ans = append(ans, strVal(val.Index(i)))
+		}
+		sort.Strings(ans)
+		return fmt.Sprintf("%v", ans)
+	case reflect.Chan, reflect.Func, reflect.Ptr:
+		return val.Kind().String()
+	case reflect.Struct:
+		var x source.Analyzer
+		if val.Type() != reflect.TypeOf(x) {
+			return val.Kind().String()
+		}
+		// this is sort of ugly, but usable
+		str := val.FieldByName("Analyzer").Elem().FieldByName("Doc").String()
+		ix := strings.Index(str, "\n")
+		if ix == -1 {
+			ix = len(str)
+		}
+		return str[:ix]
+	case reflect.String:
+		return fmt.Sprintf("%q", val.Interface())
+	case reflect.Map:
+		ans := []string{}
+		iter := val.MapRange()
+		for iter.Next() {
+			k := iter.Key()
+			v := iter.Value()
+			ans = append(ans, fmt.Sprintf("%s:%s, ", strVal(k), strVal(v)))
+		}
+		sort.Strings(ans)
+		return fmt.Sprintf("%v", ans)
+	}
+	return fmt.Sprintf("??%s??", val.Type())
+}

internal/lsp/debug/serve.go

@@ -680,6 +680,9 @@ Unknown page
 		}
 		return s
 	},
+	"options": func(s *cache.Session) []string {
+		return showOptions(s.Options())
+	},
 })
 
 var mainTmpl = template.Must(template.Must(baseTemplate.Clone()).Parse(`
@@ -779,6 +782,8 @@ From: <b>{{template "cachelink" .Cache.ID}}</b><br>
 <ul>{{range .Views}}<li>{{.Name}} is {{template "viewlink" .ID}} in {{.Folder}}</li>{{end}}</ul>
 <h2>Overlays</h2>
 <ul>{{range .Overlays}}<li>{{template "filelink" .}}</li>{{end}}</ul>
+<h2>Options</h2>
+{{range options .}}<p>{{.}}{{end}}
 {{end}}
 `))