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// Copyright 2022 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
package syntax
import "go/constant"
// A Type represents a type of Go.
// All types implement the Type interface.
// (This type originally lived in types2. We moved it here
// so we could depend on it from other packages without
// introducing a circularity.)
type Type interface {
// Underlying returns the underlying type of a type.
Underlying() Type
// String returns a string representation of a type.
String() string
}
// Expressions in the syntax package provide storage for
// the typechecker to record its results. This interface
// is the mechanism the typechecker uses to record results,
// and clients use to retrieve those results.
type typeInfo interface {
SetTypeInfo(TypeAndValue)
GetTypeInfo() TypeAndValue
}
// A TypeAndValue records the type information, constant
// value if known, and various other flags associated with
// an expression.
// This type is similar to types2.TypeAndValue, but exposes
// none of types2's internals.
type TypeAndValue struct {
Type Type
Value constant.Value
exprFlags
}
type exprFlags uint8
func (f exprFlags) IsVoid() bool { return f&1 != 0 }
func (f exprFlags) IsType() bool { return f&2 != 0 }
func (f exprFlags) IsBuiltin() bool { return f&4 != 0 }
func (f exprFlags) IsValue() bool { return f&8 != 0 }
func (f exprFlags) IsNil() bool { return f&16 != 0 }
func (f exprFlags) Addressable() bool { return f&32 != 0 }
func (f exprFlags) Assignable() bool { return f&64 != 0 }
func (f exprFlags) HasOk() bool { return f&128 != 0 }
func (f *exprFlags) SetIsVoid() { *f |= 1 }
func (f *exprFlags) SetIsType() { *f |= 2 }
func (f *exprFlags) SetIsBuiltin() { *f |= 4 }
func (f *exprFlags) SetIsValue() { *f |= 8 }
func (f *exprFlags) SetIsNil() { *f |= 16 }
func (f *exprFlags) SetAddressable() { *f |= 32 }
func (f *exprFlags) SetAssignable() { *f |= 64 }
func (f *exprFlags) SetHasOk() { *f |= 128 }
// a typeAndValue contains the results of typechecking an expression.
// It is embedded in expression nodes.
type typeAndValue struct {
tv TypeAndValue
}
func (x *typeAndValue) SetTypeInfo(tv TypeAndValue) {
x.tv = tv
}
func (x *typeAndValue) GetTypeInfo() TypeAndValue {
return x.tv
}