| 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 | // This file implements writing of types. The functionality is lifted |
| 6 | // directly from go/types, but now contains various modifications for |
| 7 | // nicer output. |
| 8 | // |
| 9 | // TODO(gri) back-port once we have a fixed interface and once the |
| 10 | // go/types API is not frozen anymore for the 1.3 release; and remove |
| 11 | // this implementation if possible. |
| 12 | |
| 13 | package main |
| 14 | |
| 15 | import "go/types" |
| 16 | |
| 17 | func (p *printer) writeType(this *types.Package, typ types.Type) { |
| 18 | p.writeTypeInternal(this, typ, make([]types.Type, 8)) |
| 19 | } |
| 20 | |
| 21 | // From go/types - leave for now to ease back-porting this code. |
| 22 | const GcCompatibilityMode = false |
| 23 | |
| 24 | func (p *printer) writeTypeInternal(this *types.Package, typ types.Type, visited []types.Type) { |
| 25 | // Theoretically, this is a quadratic lookup algorithm, but in |
| 26 | // practice deeply nested composite types with unnamed component |
| 27 | // types are uncommon. This code is likely more efficient than |
| 28 | // using a map. |
| 29 | for _, t := range visited { |
| 30 | if t == typ { |
| 31 | p.printf("○%T", typ) // cycle to typ |
| 32 | return |
| 33 | } |
| 34 | } |
| 35 | visited = append(visited, typ) |
| 36 | |
| 37 | switch t := typ.(type) { |
| 38 | case nil: |
| 39 | p.print("<nil>") |
| 40 | |
| 41 | case *types.Basic: |
| 42 | if t.Kind() == types.UnsafePointer { |
| 43 | p.print("unsafe.") |
| 44 | } |
| 45 | if GcCompatibilityMode { |
| 46 | // forget the alias names |
| 47 | switch t.Kind() { |
| 48 | case types.Byte: |
| 49 | t = types.Typ[types.Uint8] |
| 50 | case types.Rune: |
| 51 | t = types.Typ[types.Int32] |
| 52 | } |
| 53 | } |
| 54 | p.print(t.Name()) |
| 55 | |
| 56 | case *types.Array: |
| 57 | p.printf("[%d]", t.Len()) |
| 58 | p.writeTypeInternal(this, t.Elem(), visited) |
| 59 | |
| 60 | case *types.Slice: |
| 61 | p.print("[]") |
| 62 | p.writeTypeInternal(this, t.Elem(), visited) |
| 63 | |
| 64 | case *types.Struct: |
| 65 | n := t.NumFields() |
| 66 | if n == 0 { |
| 67 | p.print("struct{}") |
| 68 | return |
| 69 | } |
| 70 | |
| 71 | p.print("struct {\n") |
| 72 | p.indent++ |
| 73 | for i := 0; i < n; i++ { |
| 74 | f := t.Field(i) |
| 75 | if !f.Anonymous() { |
| 76 | p.printf("%s ", f.Name()) |
| 77 | } |
| 78 | p.writeTypeInternal(this, f.Type(), visited) |
| 79 | if tag := t.Tag(i); tag != "" { |
| 80 | p.printf(" %q", tag) |
| 81 | } |
| 82 | p.print("\n") |
| 83 | } |
| 84 | p.indent-- |
| 85 | p.print("}") |
| 86 | |
| 87 | case *types.Pointer: |
| 88 | p.print("*") |
| 89 | p.writeTypeInternal(this, t.Elem(), visited) |
| 90 | |
| 91 | case *types.Tuple: |
| 92 | p.writeTuple(this, t, false, visited) |
| 93 | |
| 94 | case *types.Signature: |
| 95 | p.print("func") |
| 96 | p.writeSignatureInternal(this, t, visited) |
| 97 | |
| 98 | case *types.Interface: |
| 99 | // We write the source-level methods and embedded types rather |
| 100 | // than the actual method set since resolved method signatures |
| 101 | // may have non-printable cycles if parameters have anonymous |
| 102 | // interface types that (directly or indirectly) embed the |
| 103 | // current interface. For instance, consider the result type |
| 104 | // of m: |
| 105 | // |
| 106 | // type T interface{ |
| 107 | // m() interface{ T } |
| 108 | // } |
| 109 | // |
| 110 | n := t.NumMethods() |
| 111 | if n == 0 { |
| 112 | p.print("interface{}") |
| 113 | return |
| 114 | } |
| 115 | |
| 116 | p.print("interface {\n") |
| 117 | p.indent++ |
| 118 | if GcCompatibilityMode { |
| 119 | // print flattened interface |
| 120 | // (useful to compare against gc-generated interfaces) |
| 121 | for i := 0; i < n; i++ { |
| 122 | m := t.Method(i) |
| 123 | p.print(m.Name()) |
| 124 | p.writeSignatureInternal(this, m.Type().(*types.Signature), visited) |
| 125 | p.print("\n") |
| 126 | } |
| 127 | } else { |
| 128 | // print explicit interface methods and embedded types |
| 129 | for i, n := 0, t.NumExplicitMethods(); i < n; i++ { |
| 130 | m := t.ExplicitMethod(i) |
| 131 | p.print(m.Name()) |
| 132 | p.writeSignatureInternal(this, m.Type().(*types.Signature), visited) |
| 133 | p.print("\n") |
| 134 | } |
| 135 | for i, n := 0, t.NumEmbeddeds(); i < n; i++ { |
| 136 | typ := t.EmbeddedType(i) |
| 137 | p.writeTypeInternal(this, typ, visited) |
| 138 | p.print("\n") |
| 139 | } |
| 140 | } |
| 141 | p.indent-- |
| 142 | p.print("}") |
| 143 | |
| 144 | case *types.Map: |
| 145 | p.print("map[") |
| 146 | p.writeTypeInternal(this, t.Key(), visited) |
| 147 | p.print("]") |
| 148 | p.writeTypeInternal(this, t.Elem(), visited) |
| 149 | |
| 150 | case *types.Chan: |
| 151 | var s string |
| 152 | var parens bool |
| 153 | switch t.Dir() { |
| 154 | case types.SendRecv: |
| 155 | s = "chan " |
| 156 | // chan (<-chan T) requires parentheses |
| 157 | if c, _ := t.Elem().(*types.Chan); c != nil && c.Dir() == types.RecvOnly { |
| 158 | parens = true |
| 159 | } |
| 160 | case types.SendOnly: |
| 161 | s = "chan<- " |
| 162 | case types.RecvOnly: |
| 163 | s = "<-chan " |
| 164 | default: |
| 165 | panic("unreachable") |
| 166 | } |
| 167 | p.print(s) |
| 168 | if parens { |
| 169 | p.print("(") |
| 170 | } |
| 171 | p.writeTypeInternal(this, t.Elem(), visited) |
| 172 | if parens { |
| 173 | p.print(")") |
| 174 | } |
| 175 | |
| 176 | case *types.Named: |
| 177 | s := "<Named w/o object>" |
| 178 | if obj := t.Obj(); obj != nil { |
| 179 | if pkg := obj.Pkg(); pkg != nil { |
| 180 | if pkg != this { |
| 181 | p.print(pkg.Path()) |
| 182 | p.print(".") |
| 183 | } |
| 184 | // TODO(gri): function-local named types should be displayed |
| 185 | // differently from named types at package level to avoid |
| 186 | // ambiguity. |
| 187 | } |
| 188 | s = obj.Name() |
| 189 | } |
| 190 | p.print(s) |
| 191 | |
| 192 | default: |
| 193 | // For externally defined implementations of Type. |
| 194 | p.print(t.String()) |
| 195 | } |
| 196 | } |
| 197 | |
| 198 | func (p *printer) writeTuple(this *types.Package, tup *types.Tuple, variadic bool, visited []types.Type) { |
| 199 | p.print("(") |
| 200 | for i, n := 0, tup.Len(); i < n; i++ { |
| 201 | if i > 0 { |
| 202 | p.print(", ") |
| 203 | } |
| 204 | v := tup.At(i) |
| 205 | if name := v.Name(); name != "" { |
| 206 | p.print(name) |
| 207 | p.print(" ") |
| 208 | } |
| 209 | typ := v.Type() |
| 210 | if variadic && i == n-1 { |
| 211 | p.print("...") |
| 212 | typ = typ.(*types.Slice).Elem() |
| 213 | } |
| 214 | p.writeTypeInternal(this, typ, visited) |
| 215 | } |
| 216 | p.print(")") |
| 217 | } |
| 218 | |
| 219 | func (p *printer) writeSignature(this *types.Package, sig *types.Signature) { |
| 220 | p.writeSignatureInternal(this, sig, make([]types.Type, 8)) |
| 221 | } |
| 222 | |
| 223 | func (p *printer) writeSignatureInternal(this *types.Package, sig *types.Signature, visited []types.Type) { |
| 224 | p.writeTuple(this, sig.Params(), sig.Variadic(), visited) |
| 225 | |
| 226 | res := sig.Results() |
| 227 | n := res.Len() |
| 228 | if n == 0 { |
| 229 | // no result |
| 230 | return |
| 231 | } |
| 232 | |
| 233 | p.print(" ") |
| 234 | if n == 1 && res.At(0).Name() == "" { |
| 235 | // single unnamed result |
| 236 | p.writeTypeInternal(this, res.At(0).Type(), visited) |
| 237 | return |
| 238 | } |
| 239 | |
| 240 | // multiple or named result(s) |
| 241 | p.writeTuple(this, res, false, visited) |
| 242 | } |
| 243 |
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