| 1 | // Copyright 2013 The Go Authors. All rights reserved. |
|---|---|
| 2 | // Use of this source code is governed by a BSD-style |
| 3 | // license that can be found in the LICENSE file. |
| 4 | |
| 5 | package main |
| 6 | |
| 7 | import ( |
| 8 | "fmt" |
| 9 | "go/ast" |
| 10 | "go/build" |
| 11 | "go/token" |
| 12 | "os" |
| 13 | "path" |
| 14 | "path/filepath" |
| 15 | "sort" |
| 16 | "strings" |
| 17 | |
| 18 | "golang.org/x/tools/cmd/guru/serial" |
| 19 | "golang.org/x/tools/go/ast/astutil" |
| 20 | ) |
| 21 | |
| 22 | // what reports all the information about the query selection that can be |
| 23 | // obtained from parsing only its containing source file. |
| 24 | // It is intended to be a very low-latency query callable from GUI |
| 25 | // tools, e.g. to populate a menu of options of slower queries about |
| 26 | // the selected location. |
| 27 | func what(q *Query) error { |
| 28 | qpos, err := fastQueryPos(q.Build, q.Pos) |
| 29 | if err != nil { |
| 30 | return err |
| 31 | } |
| 32 | |
| 33 | // (ignore errors) |
| 34 | srcdir, importPath, _ := guessImportPath(qpos.fset.File(qpos.start).Name(), q.Build) |
| 35 | |
| 36 | // Determine which query modes are applicable to the selection. |
| 37 | enable := map[string]bool{ |
| 38 | "describe": true, // any syntax; always enabled |
| 39 | } |
| 40 | |
| 41 | if qpos.end > qpos.start { |
| 42 | enable["freevars"] = true // nonempty selection? |
| 43 | } |
| 44 | |
| 45 | for _, n := range qpos.path { |
| 46 | switch n := n.(type) { |
| 47 | case *ast.Ident: |
| 48 | enable["definition"] = true |
| 49 | enable["referrers"] = true |
| 50 | enable["implements"] = true |
| 51 | case *ast.CallExpr: |
| 52 | enable["callees"] = true |
| 53 | case *ast.FuncDecl: |
| 54 | enable["callers"] = true |
| 55 | enable["callstack"] = true |
| 56 | case *ast.SendStmt: |
| 57 | enable["peers"] = true |
| 58 | case *ast.UnaryExpr: |
| 59 | if n.Op == token.ARROW { |
| 60 | enable["peers"] = true |
| 61 | } |
| 62 | } |
| 63 | |
| 64 | // For implements, we approximate findInterestingNode. |
| 65 | if _, ok := enable["implements"]; !ok { |
| 66 | switch n.(type) { |
| 67 | case *ast.ArrayType, |
| 68 | *ast.StructType, |
| 69 | *ast.FuncType, |
| 70 | *ast.InterfaceType, |
| 71 | *ast.MapType, |
| 72 | *ast.ChanType: |
| 73 | enable["implements"] = true |
| 74 | } |
| 75 | } |
| 76 | |
| 77 | // For pointsto and whicherrs, we approximate findInterestingNode. |
| 78 | if _, ok := enable["pointsto"]; !ok { |
| 79 | switch n.(type) { |
| 80 | case ast.Stmt, |
| 81 | *ast.ArrayType, |
| 82 | *ast.StructType, |
| 83 | *ast.FuncType, |
| 84 | *ast.InterfaceType, |
| 85 | *ast.MapType, |
| 86 | *ast.ChanType: |
| 87 | // not an expression |
| 88 | enable["pointsto"] = false |
| 89 | enable["whicherrs"] = false |
| 90 | |
| 91 | case ast.Expr, ast.Decl, *ast.ValueSpec: |
| 92 | // an expression, maybe |
| 93 | enable["pointsto"] = true |
| 94 | enable["whicherrs"] = true |
| 95 | |
| 96 | default: |
| 97 | // Comment, Field, KeyValueExpr, etc: ascend. |
| 98 | } |
| 99 | } |
| 100 | } |
| 101 | |
| 102 | // If we don't have an exact selection, disable modes that need one. |
| 103 | if !qpos.exact { |
| 104 | enable["callees"] = false |
| 105 | enable["pointsto"] = false |
| 106 | enable["whicherrs"] = false |
| 107 | enable["describe"] = false |
| 108 | } |
| 109 | |
| 110 | var modes []string |
| 111 | for mode := range enable { |
| 112 | modes = append(modes, mode) |
| 113 | } |
| 114 | sort.Strings(modes) |
| 115 | |
| 116 | // Find the object referred to by the selection (if it's an |
| 117 | // identifier) and report the position of each identifier |
| 118 | // that refers to the same object. |
| 119 | // |
| 120 | // This may return spurious matches (e.g. struct fields) because |
| 121 | // it uses the best-effort name resolution done by go/parser. |
| 122 | var sameids []token.Pos |
| 123 | var object string |
| 124 | if id, ok := qpos.path[0].(*ast.Ident); ok { |
| 125 | if id.Obj == nil { |
| 126 | // An unresolved identifier is potentially a package name. |
| 127 | // Resolve them with a simple importer (adds ~100µs). |
| 128 | importer := func(imports map[string]*ast.Object, path string) (*ast.Object, error) { |
| 129 | pkg, ok := imports[path] |
| 130 | if !ok { |
| 131 | pkg = &ast.Object{ |
| 132 | Kind: ast.Pkg, |
| 133 | Name: filepath.Base(path), // a guess |
| 134 | } |
| 135 | imports[path] = pkg |
| 136 | } |
| 137 | return pkg, nil |
| 138 | } |
| 139 | f := qpos.path[len(qpos.path)-1].(*ast.File) |
| 140 | ast.NewPackage(qpos.fset, map[string]*ast.File{"": f}, importer, nil) |
| 141 | } |
| 142 | |
| 143 | if id.Obj != nil { |
| 144 | object = id.Obj.Name |
| 145 | decl := qpos.path[len(qpos.path)-1] |
| 146 | ast.Inspect(decl, func(n ast.Node) bool { |
| 147 | if n, ok := n.(*ast.Ident); ok && n.Obj == id.Obj { |
| 148 | sameids = append(sameids, n.Pos()) |
| 149 | } |
| 150 | return true |
| 151 | }) |
| 152 | } |
| 153 | } |
| 154 | |
| 155 | q.Output(qpos.fset, &whatResult{ |
| 156 | path: qpos.path, |
| 157 | srcdir: srcdir, |
| 158 | importPath: importPath, |
| 159 | modes: modes, |
| 160 | object: object, |
| 161 | sameids: sameids, |
| 162 | }) |
| 163 | return nil |
| 164 | } |
| 165 | |
| 166 | // guessImportPath finds the package containing filename, and returns |
| 167 | // its source directory (an element of $GOPATH) and its import path |
| 168 | // relative to it. |
| 169 | // |
| 170 | // TODO(adonovan): what about _test.go files that are not part of the |
| 171 | // package? |
| 172 | func guessImportPath(filename string, buildContext *build.Context) (srcdir, importPath string, err error) { |
| 173 | absFile, err := filepath.Abs(filename) |
| 174 | if err != nil { |
| 175 | return "", "", fmt.Errorf("can't form absolute path of %s: %v", filename, err) |
| 176 | } |
| 177 | |
| 178 | absFileDir := filepath.Dir(absFile) |
| 179 | resolvedAbsFileDir, err := filepath.EvalSymlinks(absFileDir) |
| 180 | if err != nil { |
| 181 | return "", "", fmt.Errorf("can't evaluate symlinks of %s: %v", absFileDir, err) |
| 182 | } |
| 183 | |
| 184 | segmentedAbsFileDir := segments(resolvedAbsFileDir) |
| 185 | // Find the innermost directory in $GOPATH that encloses filename. |
| 186 | minD := 1024 |
| 187 | for _, gopathDir := range buildContext.SrcDirs() { |
| 188 | absDir, err := filepath.Abs(gopathDir) |
| 189 | if err != nil { |
| 190 | continue // e.g. non-existent dir on $GOPATH |
| 191 | } |
| 192 | resolvedAbsDir, err := filepath.EvalSymlinks(absDir) |
| 193 | if err != nil { |
| 194 | continue // e.g. non-existent dir on $GOPATH |
| 195 | } |
| 196 | |
| 197 | d := prefixLen(segments(resolvedAbsDir), segmentedAbsFileDir) |
| 198 | // If there are multiple matches, |
| 199 | // prefer the innermost enclosing directory |
| 200 | // (smallest d). |
| 201 | if d >= 0 && d < minD { |
| 202 | minD = d |
| 203 | srcdir = gopathDir |
| 204 | importPath = path.Join(segmentedAbsFileDir[len(segmentedAbsFileDir)-minD:]...) |
| 205 | } |
| 206 | } |
| 207 | if srcdir == "" { |
| 208 | return "", "", fmt.Errorf("directory %s is not beneath any of these GOROOT/GOPATH directories: %s", |
| 209 | filepath.Dir(absFile), strings.Join(buildContext.SrcDirs(), ", ")) |
| 210 | } |
| 211 | if importPath == "" { |
| 212 | // This happens for e.g. $GOPATH/src/a.go, but |
| 213 | // "" is not a valid path for (*go/build).Import. |
| 214 | return "", "", fmt.Errorf("cannot load package in root of source directory %s", srcdir) |
| 215 | } |
| 216 | return srcdir, importPath, nil |
| 217 | } |
| 218 | |
| 219 | func segments(path string) []string { |
| 220 | return strings.Split(path, string(os.PathSeparator)) |
| 221 | } |
| 222 | |
| 223 | // prefixLen returns the length of the remainder of y if x is a prefix |
| 224 | // of y, a negative number otherwise. |
| 225 | func prefixLen(x, y []string) int { |
| 226 | d := len(y) - len(x) |
| 227 | if d >= 0 { |
| 228 | for i := range x { |
| 229 | if y[i] != x[i] { |
| 230 | return -1 // not a prefix |
| 231 | } |
| 232 | } |
| 233 | } |
| 234 | return d |
| 235 | } |
| 236 | |
| 237 | type whatResult struct { |
| 238 | path []ast.Node |
| 239 | modes []string |
| 240 | srcdir string |
| 241 | importPath string |
| 242 | object string |
| 243 | sameids []token.Pos |
| 244 | } |
| 245 | |
| 246 | func (r *whatResult) PrintPlain(printf printfFunc) { |
| 247 | for _, n := range r.path { |
| 248 | printf(n, "%s", astutil.NodeDescription(n)) |
| 249 | } |
| 250 | printf(nil, "modes: %s", r.modes) |
| 251 | printf(nil, "srcdir: %s", r.srcdir) |
| 252 | printf(nil, "import path: %s", r.importPath) |
| 253 | for _, pos := range r.sameids { |
| 254 | printf(pos, "%s", r.object) |
| 255 | } |
| 256 | } |
| 257 | |
| 258 | func (r *whatResult) JSON(fset *token.FileSet) []byte { |
| 259 | var enclosing []serial.SyntaxNode |
| 260 | for _, n := range r.path { |
| 261 | enclosing = append(enclosing, serial.SyntaxNode{ |
| 262 | Description: astutil.NodeDescription(n), |
| 263 | Start: fset.Position(n.Pos()).Offset, |
| 264 | End: fset.Position(n.End()).Offset, |
| 265 | }) |
| 266 | } |
| 267 | |
| 268 | var sameids []string |
| 269 | for _, pos := range r.sameids { |
| 270 | sameids = append(sameids, fset.Position(pos).String()) |
| 271 | } |
| 272 | |
| 273 | return toJSON(&serial.What{ |
| 274 | Modes: r.modes, |
| 275 | SrcDir: r.srcdir, |
| 276 | ImportPath: r.importPath, |
| 277 | Enclosing: enclosing, |
| 278 | Object: r.object, |
| 279 | SameIDs: sameids, |
| 280 | }) |
| 281 | } |
| 282 |
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