1 // Copyright 2022 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 syntax
6 7 import "go/constant"
8 9 // A Type represents a type of Go.
10 // All types implement the Type interface.
11 // (This type originally lived in types2. We moved it here
12 // so we could depend on it from other packages without
13 // introducing an import cycle.)
14 type Type interface {
15 // Underlying returns the underlying type of a type.
16 // Underlying types are never Named, TypeParam, or Alias types.
17 //
18 // See https://go.dev/ref/spec#Underlying_types.
19 Underlying() Type
20 21 // String returns a string representation of a type.
22 String() string
23 }
24 25 // Expressions in the syntax package provide storage for
26 // the typechecker to record its results. This interface
27 // is the mechanism the typechecker uses to record results,
28 // and clients use to retrieve those results.
29 type typeInfo interface {
30 SetTypeInfo(TypeAndValue)
31 GetTypeInfo() TypeAndValue
32 }
33 34 // A TypeAndValue records the type information, constant
35 // value if known, and various other flags associated with
36 // an expression.
37 // This type is similar to types2.TypeAndValue, but exposes
38 // none of types2's internals.
39 type TypeAndValue struct {
40 Type Type
41 Value constant.Value
42 exprFlags
43 }
44 45 type exprFlags uint16
46 47 func (f exprFlags) IsVoid() bool { return f&1 != 0 }
48 func (f exprFlags) IsType() bool { return f&2 != 0 }
49 func (f exprFlags) IsBuiltin() bool { return f&4 != 0 } // a language builtin that resembles a function call, e.g., "make, append, new"
50 func (f exprFlags) IsValue() bool { return f&8 != 0 }
51 func (f exprFlags) IsNil() bool { return f&16 != 0 }
52 func (f exprFlags) Addressable() bool { return f&32 != 0 }
53 func (f exprFlags) Assignable() bool { return f&64 != 0 }
54 func (f exprFlags) HasOk() bool { return f&128 != 0 }
55 func (f exprFlags) IsRuntimeHelper() bool { return f&256 != 0 } // a runtime function called from transformed syntax
56 57 func (f *exprFlags) SetIsVoid() { *f |= 1 }
58 func (f *exprFlags) SetIsType() { *f |= 2 }
59 func (f *exprFlags) SetIsBuiltin() { *f |= 4 }
60 func (f *exprFlags) SetIsValue() { *f |= 8 }
61 func (f *exprFlags) SetIsNil() { *f |= 16 }
62 func (f *exprFlags) SetAddressable() { *f |= 32 }
63 func (f *exprFlags) SetAssignable() { *f |= 64 }
64 func (f *exprFlags) SetHasOk() { *f |= 128 }
65 func (f *exprFlags) SetIsRuntimeHelper() { *f |= 256 }
66 67 // a typeAndValue contains the results of typechecking an expression.
68 // It is embedded in expression nodes.
69 type typeAndValue struct {
70 tv TypeAndValue
71 }
72 73 func (x *typeAndValue) SetTypeInfo(tv TypeAndValue) {
74 x.tv = tv
75 }
76 func (x *typeAndValue) GetTypeInfo() TypeAndValue {
77 return x.tv
78 }
79