| package ssa |
| |
| // This file defines the Literal SSA value type. |
| |
| import ( |
| "fmt" |
| "strconv" |
| |
| "code.google.com/p/go.exp/go/exact" |
| "code.google.com/p/go.exp/go/types" |
| ) |
| |
| // newLiteral returns a new literal of the specified value and type. |
| // val must be valid according to the specification of Literal.Value. |
| // |
| func newLiteral(val exact.Value, typ types.Type) *Literal { |
| // This constructor exists to provide a single place to |
| // insert logging/assertions during debugging. |
| return &Literal{typ, val} |
| } |
| |
| // intLiteral returns an untyped integer literal that evaluates to i. |
| func intLiteral(i int64) *Literal { |
| return newLiteral(exact.MakeInt64(i), types.Typ[types.UntypedInt]) |
| } |
| |
| // nilLiteral returns a nil literal of the specified type, which may |
| // be any reference type, including interfaces. |
| // |
| func nilLiteral(typ types.Type) *Literal { |
| return newLiteral(exact.MakeNil(), typ) |
| } |
| |
| // zeroLiteral returns a new "zero" literal of the specified type, |
| // which must not be an array or struct type: the zero values of |
| // aggregates are well-defined but cannot be represented by Literal. |
| // |
| func zeroLiteral(t types.Type) *Literal { |
| switch t := t.(type) { |
| case *types.Basic: |
| switch { |
| case t.Info()&types.IsBoolean != 0: |
| return newLiteral(exact.MakeBool(false), t) |
| case t.Info()&types.IsNumeric != 0: |
| return newLiteral(exact.MakeInt64(0), t) |
| case t.Info()&types.IsString != 0: |
| return newLiteral(exact.MakeString(""), t) |
| case t.Kind() == types.UnsafePointer: |
| fallthrough |
| case t.Kind() == types.UntypedNil: |
| return nilLiteral(t) |
| default: |
| panic(fmt.Sprint("zeroLiteral for unexpected type:", t)) |
| } |
| case *types.Pointer, *types.Slice, *types.Interface, *types.Chan, *types.Map, *types.Signature: |
| return nilLiteral(t) |
| case *types.Named: |
| return newLiteral(zeroLiteral(t.Underlying()).Value, t) |
| case *types.Array, *types.Struct: |
| panic(fmt.Sprint("zeroLiteral applied to aggregate:", t)) |
| } |
| panic(fmt.Sprint("zeroLiteral: unexpected ", t)) |
| } |
| |
| func (l *Literal) Name() string { |
| var s string |
| if l.Value.Kind() == exact.String { |
| s = exact.StringVal(l.Value) |
| const maxLit = 20 |
| if len(s) > maxLit { |
| s = s[:maxLit-3] + "..." // abbreviate |
| } |
| s = strconv.Quote(s) |
| } else { |
| s = l.Value.String() |
| } |
| return s + ":" + l.Type_.String() |
| } |
| |
| func (l *Literal) Type() types.Type { |
| return l.Type_ |
| } |
| |
| func (l *Literal) Referrers() *[]Instruction { |
| return nil |
| } |
| |
| // IsNil returns true if this literal represents a typed or untyped nil value. |
| func (l *Literal) IsNil() bool { |
| return l.Value.Kind() == exact.Nil |
| } |
| |
| // Int64 returns the numeric value of this literal truncated to fit |
| // a signed 64-bit integer. |
| // |
| func (l *Literal) Int64() int64 { |
| switch x := l.Value; x.Kind() { |
| case exact.Int: |
| if i, ok := exact.Int64Val(x); ok { |
| return i |
| } |
| return 0 |
| case exact.Float: |
| f, _ := exact.Float64Val(x) |
| return int64(f) |
| } |
| panic(fmt.Sprintf("unexpected literal value: %T", l.Value)) |
| } |
| |
| // Uint64 returns the numeric value of this literal truncated to fit |
| // an unsigned 64-bit integer. |
| // |
| func (l *Literal) Uint64() uint64 { |
| switch x := l.Value; x.Kind() { |
| case exact.Int: |
| if u, ok := exact.Uint64Val(x); ok { |
| return u |
| } |
| return 0 |
| case exact.Float: |
| f, _ := exact.Float64Val(x) |
| return uint64(f) |
| } |
| panic(fmt.Sprintf("unexpected literal value: %T", l.Value)) |
| } |
| |
| // Float64 returns the numeric value of this literal truncated to fit |
| // a float64. |
| // |
| func (l *Literal) Float64() float64 { |
| f, _ := exact.Float64Val(l.Value) |
| return f |
| } |
| |
| // Complex128 returns the complex value of this literal truncated to |
| // fit a complex128. |
| // |
| func (l *Literal) Complex128() complex128 { |
| re, _ := exact.Float64Val(exact.Real(l.Value)) |
| im, _ := exact.Float64Val(exact.Imag(l.Value)) |
| return complex(re, im) |
| } |