| 1 | // Copyright 2014 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 | "bytes" |
| 9 | "fmt" |
| 10 | "go/constant" |
| 11 | "go/token" |
| 12 | "go/types" |
| 13 | "io" |
| 14 | "math/big" |
| 15 | ) |
| 16 | |
| 17 | // TODO(gri) use tabwriter for alignment? |
| 18 | |
| 19 | func print(w io.Writer, pkg *types.Package, filter func(types.Object) bool) { |
| 20 | var p printer |
| 21 | p.pkg = pkg |
| 22 | p.printPackage(pkg, filter) |
| 23 | p.printGccgoExtra(pkg) |
| 24 | io.Copy(w, &p.buf) |
| 25 | } |
| 26 | |
| 27 | type printer struct { |
| 28 | pkg *types.Package |
| 29 | buf bytes.Buffer |
| 30 | indent int // current indentation level |
| 31 | last byte // last byte written |
| 32 | } |
| 33 | |
| 34 | func (p *printer) print(s string) { |
| 35 | // Write the string one byte at a time. We care about the presence of |
| 36 | // newlines for indentation which we will see even in the presence of |
| 37 | // (non-corrupted) Unicode; no need to read one rune at a time. |
| 38 | for i := 0; i < len(s); i++ { |
| 39 | ch := s[i] |
| 40 | if ch != '\n' && p.last == '\n' { |
| 41 | // Note: This could lead to a range overflow for very large |
| 42 | // indentations, but it's extremely unlikely to happen for |
| 43 | // non-pathological code. |
| 44 | p.buf.WriteString("\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t"[:p.indent]) |
| 45 | } |
| 46 | p.buf.WriteByte(ch) |
| 47 | p.last = ch |
| 48 | } |
| 49 | } |
| 50 | |
| 51 | func (p *printer) printf(format string, args ...interface{}) { |
| 52 | p.print(fmt.Sprintf(format, args...)) |
| 53 | } |
| 54 | |
| 55 | // methodsFor returns the named type and corresponding methods if the type |
| 56 | // denoted by obj is not an interface and has methods. Otherwise it returns |
| 57 | // the zero value. |
| 58 | func methodsFor(obj *types.TypeName) (*types.Named, []*types.Selection) { |
| 59 | named, _ := obj.Type().(*types.Named) |
| 60 | if named == nil { |
| 61 | // A type name's type can also be the |
| 62 | // exported basic type unsafe.Pointer. |
| 63 | return nil, nil |
| 64 | } |
| 65 | if _, ok := named.Underlying().(*types.Interface); ok { |
| 66 | // ignore interfaces |
| 67 | return nil, nil |
| 68 | } |
| 69 | methods := combinedMethodSet(named) |
| 70 | if len(methods) == 0 { |
| 71 | return nil, nil |
| 72 | } |
| 73 | return named, methods |
| 74 | } |
| 75 | |
| 76 | func (p *printer) printPackage(pkg *types.Package, filter func(types.Object) bool) { |
| 77 | // collect objects by kind |
| 78 | var ( |
| 79 | consts []*types.Const |
| 80 | typem []*types.Named // non-interface types with methods |
| 81 | typez []*types.TypeName // interfaces or types without methods |
| 82 | vars []*types.Var |
| 83 | funcs []*types.Func |
| 84 | builtins []*types.Builtin |
| 85 | methods = make(map[*types.Named][]*types.Selection) // method sets for named types |
| 86 | ) |
| 87 | scope := pkg.Scope() |
| 88 | for _, name := range scope.Names() { |
| 89 | obj := scope.Lookup(name) |
| 90 | if obj.Exported() { |
| 91 | // collect top-level exported and possibly filtered objects |
| 92 | if filter == nil || filter(obj) { |
| 93 | switch obj := obj.(type) { |
| 94 | case *types.Const: |
| 95 | consts = append(consts, obj) |
| 96 | case *types.TypeName: |
| 97 | // group into types with methods and types without |
| 98 | if named, m := methodsFor(obj); named != nil { |
| 99 | typem = append(typem, named) |
| 100 | methods[named] = m |
| 101 | } else { |
| 102 | typez = append(typez, obj) |
| 103 | } |
| 104 | case *types.Var: |
| 105 | vars = append(vars, obj) |
| 106 | case *types.Func: |
| 107 | funcs = append(funcs, obj) |
| 108 | case *types.Builtin: |
| 109 | // for unsafe.Sizeof, etc. |
| 110 | builtins = append(builtins, obj) |
| 111 | } |
| 112 | } |
| 113 | } else if filter == nil { |
| 114 | // no filtering: collect top-level unexported types with methods |
| 115 | if obj, _ := obj.(*types.TypeName); obj != nil { |
| 116 | // see case *types.TypeName above |
| 117 | if named, m := methodsFor(obj); named != nil { |
| 118 | typem = append(typem, named) |
| 119 | methods[named] = m |
| 120 | } |
| 121 | } |
| 122 | } |
| 123 | } |
| 124 | |
| 125 | p.printf("package %s // %q\n", pkg.Name(), pkg.Path()) |
| 126 | |
| 127 | p.printDecl("const", len(consts), func() { |
| 128 | for _, obj := range consts { |
| 129 | p.printObj(obj) |
| 130 | p.print("\n") |
| 131 | } |
| 132 | }) |
| 133 | |
| 134 | p.printDecl("var", len(vars), func() { |
| 135 | for _, obj := range vars { |
| 136 | p.printObj(obj) |
| 137 | p.print("\n") |
| 138 | } |
| 139 | }) |
| 140 | |
| 141 | p.printDecl("type", len(typez), func() { |
| 142 | for _, obj := range typez { |
| 143 | p.printf("%s ", obj.Name()) |
| 144 | typ := obj.Type() |
| 145 | if isAlias(obj) { |
| 146 | p.print("= ") |
| 147 | p.writeType(p.pkg, typ) |
| 148 | } else { |
| 149 | p.writeType(p.pkg, typ.Underlying()) |
| 150 | } |
| 151 | p.print("\n") |
| 152 | } |
| 153 | }) |
| 154 | |
| 155 | // non-interface types with methods |
| 156 | for _, named := range typem { |
| 157 | first := true |
| 158 | if obj := named.Obj(); obj.Exported() { |
| 159 | if first { |
| 160 | p.print("\n") |
| 161 | first = false |
| 162 | } |
| 163 | p.printf("type %s ", obj.Name()) |
| 164 | p.writeType(p.pkg, named.Underlying()) |
| 165 | p.print("\n") |
| 166 | } |
| 167 | for _, m := range methods[named] { |
| 168 | if obj := m.Obj(); obj.Exported() { |
| 169 | if first { |
| 170 | p.print("\n") |
| 171 | first = false |
| 172 | } |
| 173 | p.printFunc(m.Recv(), obj.(*types.Func)) |
| 174 | p.print("\n") |
| 175 | } |
| 176 | } |
| 177 | } |
| 178 | |
| 179 | if len(funcs) > 0 { |
| 180 | p.print("\n") |
| 181 | for _, obj := range funcs { |
| 182 | p.printFunc(nil, obj) |
| 183 | p.print("\n") |
| 184 | } |
| 185 | } |
| 186 | |
| 187 | // TODO(gri) better handling of builtins (package unsafe only) |
| 188 | if len(builtins) > 0 { |
| 189 | p.print("\n") |
| 190 | for _, obj := range builtins { |
| 191 | p.printf("func %s() // builtin\n", obj.Name()) |
| 192 | } |
| 193 | } |
| 194 | |
| 195 | p.print("\n") |
| 196 | } |
| 197 | |
| 198 | func (p *printer) printDecl(keyword string, n int, printGroup func()) { |
| 199 | switch n { |
| 200 | case 0: |
| 201 | // nothing to do |
| 202 | case 1: |
| 203 | p.printf("\n%s ", keyword) |
| 204 | printGroup() |
| 205 | default: |
| 206 | p.printf("\n%s (\n", keyword) |
| 207 | p.indent++ |
| 208 | printGroup() |
| 209 | p.indent-- |
| 210 | p.print(")\n") |
| 211 | } |
| 212 | } |
| 213 | |
| 214 | // absInt returns the absolute value of v as a *big.Int. |
| 215 | // v must be a numeric value. |
| 216 | func absInt(v constant.Value) *big.Int { |
| 217 | // compute big-endian representation of v |
| 218 | b := constant.Bytes(v) // little-endian |
| 219 | for i, j := 0, len(b)-1; i < j; i, j = i+1, j-1 { |
| 220 | b[i], b[j] = b[j], b[i] |
| 221 | } |
| 222 | return new(big.Int).SetBytes(b) |
| 223 | } |
| 224 | |
| 225 | var ( |
| 226 | one = big.NewRat(1, 1) |
| 227 | ten = big.NewRat(10, 1) |
| 228 | ) |
| 229 | |
| 230 | // floatString returns the string representation for a |
| 231 | // numeric value v in normalized floating-point format. |
| 232 | func floatString(v constant.Value) string { |
| 233 | if constant.Sign(v) == 0 { |
| 234 | return "0.0" |
| 235 | } |
| 236 | // x != 0 |
| 237 | |
| 238 | // convert |v| into a big.Rat x |
| 239 | x := new(big.Rat).SetFrac(absInt(constant.Num(v)), absInt(constant.Denom(v))) |
| 240 | |
| 241 | // normalize x and determine exponent e |
| 242 | // (This is not very efficient, but also not speed-critical.) |
| 243 | var e int |
| 244 | for x.Cmp(ten) >= 0 { |
| 245 | x.Quo(x, ten) |
| 246 | e++ |
| 247 | } |
| 248 | for x.Cmp(one) < 0 { |
| 249 | x.Mul(x, ten) |
| 250 | e-- |
| 251 | } |
| 252 | |
| 253 | // TODO(gri) Values such as 1/2 are easier to read in form 0.5 |
| 254 | // rather than 5.0e-1. Similarly, 1.0e1 is easier to read as |
| 255 | // 10.0. Fine-tune best exponent range for readability. |
| 256 | |
| 257 | s := x.FloatString(100) // good-enough precision |
| 258 | |
| 259 | // trim trailing 0's |
| 260 | i := len(s) |
| 261 | for i > 0 && s[i-1] == '0' { |
| 262 | i-- |
| 263 | } |
| 264 | s = s[:i] |
| 265 | |
| 266 | // add a 0 if the number ends in decimal point |
| 267 | if len(s) > 0 && s[len(s)-1] == '.' { |
| 268 | s += "0" |
| 269 | } |
| 270 | |
| 271 | // add exponent and sign |
| 272 | if e != 0 { |
| 273 | s += fmt.Sprintf("e%+d", e) |
| 274 | } |
| 275 | if constant.Sign(v) < 0 { |
| 276 | s = "-" + s |
| 277 | } |
| 278 | |
| 279 | // TODO(gri) If v is a "small" fraction (i.e., numerator and denominator |
| 280 | // are just a small number of decimal digits), add the exact fraction as |
| 281 | // a comment. For instance: 3.3333...e-1 /* = 1/3 */ |
| 282 | |
| 283 | return s |
| 284 | } |
| 285 | |
| 286 | // valString returns the string representation for the value v. |
| 287 | // Setting floatFmt forces an integer value to be formatted in |
| 288 | // normalized floating-point format. |
| 289 | // TODO(gri) Move this code into package constant. |
| 290 | func valString(v constant.Value, floatFmt bool) string { |
| 291 | switch v.Kind() { |
| 292 | case constant.Int: |
| 293 | if floatFmt { |
| 294 | return floatString(v) |
| 295 | } |
| 296 | case constant.Float: |
| 297 | return floatString(v) |
| 298 | case constant.Complex: |
| 299 | re := constant.Real(v) |
| 300 | im := constant.Imag(v) |
| 301 | var s string |
| 302 | if constant.Sign(re) != 0 { |
| 303 | s = floatString(re) |
| 304 | if constant.Sign(im) >= 0 { |
| 305 | s += " + " |
| 306 | } else { |
| 307 | s += " - " |
| 308 | im = constant.UnaryOp(token.SUB, im, 0) // negate im |
| 309 | } |
| 310 | } |
| 311 | // im != 0, otherwise v would be constant.Int or constant.Float |
| 312 | return s + floatString(im) + "i" |
| 313 | } |
| 314 | return v.String() |
| 315 | } |
| 316 | |
| 317 | func (p *printer) printObj(obj types.Object) { |
| 318 | p.print(obj.Name()) |
| 319 | |
| 320 | typ, basic := obj.Type().Underlying().(*types.Basic) |
| 321 | if basic && typ.Info()&types.IsUntyped != 0 { |
| 322 | // don't write untyped types |
| 323 | } else { |
| 324 | p.print(" ") |
| 325 | p.writeType(p.pkg, obj.Type()) |
| 326 | } |
| 327 | |
| 328 | if obj, ok := obj.(*types.Const); ok { |
| 329 | floatFmt := basic && typ.Info()&(types.IsFloat|types.IsComplex) != 0 |
| 330 | p.print(" = ") |
| 331 | p.print(valString(obj.Val(), floatFmt)) |
| 332 | } |
| 333 | } |
| 334 | |
| 335 | func (p *printer) printFunc(recvType types.Type, obj *types.Func) { |
| 336 | p.print("func ") |
| 337 | sig := obj.Type().(*types.Signature) |
| 338 | if recvType != nil { |
| 339 | p.print("(") |
| 340 | p.writeType(p.pkg, recvType) |
| 341 | p.print(") ") |
| 342 | } |
| 343 | p.print(obj.Name()) |
| 344 | p.writeSignature(p.pkg, sig) |
| 345 | } |
| 346 | |
| 347 | // combinedMethodSet returns the method set for a named type T |
| 348 | // merged with all the methods of *T that have different names than |
| 349 | // the methods of T. |
| 350 | // |
| 351 | // combinedMethodSet is analogous to types/typeutil.IntuitiveMethodSet |
| 352 | // but doesn't require a MethodSetCache. |
| 353 | // TODO(gri) If this functionality doesn't change over time, consider |
| 354 | // just calling IntuitiveMethodSet eventually. |
| 355 | func combinedMethodSet(T *types.Named) []*types.Selection { |
| 356 | // method set for T |
| 357 | mset := types.NewMethodSet(T) |
| 358 | var res []*types.Selection |
| 359 | for i, n := 0, mset.Len(); i < n; i++ { |
| 360 | res = append(res, mset.At(i)) |
| 361 | } |
| 362 | |
| 363 | // add all *T methods with names different from T methods |
| 364 | pmset := types.NewMethodSet(types.NewPointer(T)) |
| 365 | for i, n := 0, pmset.Len(); i < n; i++ { |
| 366 | pm := pmset.At(i) |
| 367 | if obj := pm.Obj(); mset.Lookup(obj.Pkg(), obj.Name()) == nil { |
| 368 | res = append(res, pm) |
| 369 | } |
| 370 | } |
| 371 | |
| 372 | return res |
| 373 | } |
| 374 |
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