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gotypes,build: pointer dereference (#61)

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Provides a method on `gotypes.Component` to allow pointer dereference. This will enable `gotypes` helpers to be used with struct pointer arguments, for example.

Updates #53 
Fixes #54
This commit is contained in:
Michael McLoughlin
2019-01-27 19:22:21 -08:00
committed by GitHub
parent eb225e9d2c
commit 9eb409b935
9 changed files with 137 additions and 29 deletions
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66
gotypes/components.go
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@@ -7,6 +7,8 @@ import (
"go/types"
"strconv"
"github.com/mmcloughlin/avo/reg"
"github.com/mmcloughlin/avo/operand"
)
@@ -27,13 +29,14 @@ type Component interface {
// resolution time.
Resolve() (*Basic, error)
Base() Component // base pointer of a string or slice
Len() Component // length of a string or slice
Cap() Component // capacity of a slice
Real() Component // real part of a complex value
Imag() Component // imaginary part of a complex value
Index(int) Component // index into an array
Field(string) Component // access a struct field
Dereference(r reg.Register) Component // dereference a pointer
Base() Component // base pointer of a string or slice
Len() Component // length of a string or slice
Cap() Component // capacity of a slice
Real() Component // real part of a complex value
Imag() Component // imaginary part of a complex value
Index(int) Component // index into an array
Field(string) Component // access a struct field
}
// componenterr is an error that also provides a null implementation of the
@@ -45,28 +48,27 @@ func errorf(format string, args ...interface{}) Component {
return componenterr(fmt.Sprintf(format, args...))
}
func (c componenterr) Error() string { return string(c) }
func (c componenterr) Resolve() (*Basic, error) { return nil, c }
func (c componenterr) Base() Component { return c }
func (c componenterr) Len() Component { return c }
func (c componenterr) Cap() Component { return c }
func (c componenterr) Real() Component { return c }
func (c componenterr) Imag() Component { return c }
func (c componenterr) Index(int) Component { return c }
func (c componenterr) Field(string) Component { return c }
func (c componenterr) Error() string { return string(c) }
func (c componenterr) Resolve() (*Basic, error) { return nil, c }
func (c componenterr) Dereference(r reg.Register) Component { return c }
func (c componenterr) Base() Component { return c }
func (c componenterr) Len() Component { return c }
func (c componenterr) Cap() Component { return c }
func (c componenterr) Real() Component { return c }
func (c componenterr) Imag() Component { return c }
func (c componenterr) Index(int) Component { return c }
func (c componenterr) Field(string) Component { return c }
type component struct {
name string
typ types.Type
offset int
typ types.Type
addr operand.Mem
}
// NewComponent builds a component for the named type at the given memory offset.
func NewComponent(name string, t types.Type, offset int) Component {
// NewComponent builds a component for the named type at the given address.
func NewComponent(t types.Type, addr operand.Mem) Component {
return &component{
name: name,
typ: t,
offset: offset,
typ: t,
addr: addr,
}
}
@@ -76,11 +78,19 @@ func (c *component) Resolve() (*Basic, error) {
return nil, errors.New("component is not primitive")
}
return &Basic{
Addr: operand.NewParamAddr(c.name, c.offset),
Addr: c.addr,
Type: b,
}, nil
}
func (c *component) Dereference(r reg.Register) Component {
p, ok := c.typ.Underlying().(*types.Pointer)
if !ok {
return errorf("not pointer type")
}
return NewComponent(p.Elem(), operand.Mem{Base: r})
}
// Reference: https://github.com/golang/go/blob/50bd1c4d4eb4fac8ddeb5f063c099daccfb71b26/src/reflect/value.go#L1800-L1804
//
// type SliceHeader struct {
@@ -194,8 +204,10 @@ func (c *component) Field(n string) Component {
func (c *component) sub(suffix string, offset int, t types.Type) *component {
s := *c
s.name += suffix
s.offset += offset
if s.addr.Symbol.Name != "" {
s.addr.Symbol.Name += suffix
}
s.addr = s.addr.Offset(offset)
s.typ = t
return &s
}