forked from ipld/go-ipld-prime
/
genStructReprTuple.go
443 lines (413 loc) · 15 KB
/
genStructReprTuple.go
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package gengo
import (
"io"
"strconv"
"github.com/ipld/go-ipld-prime/schema"
"github.com/ipld/go-ipld-prime/schema/gen/go/mixins"
)
var _ TypeGenerator = &structReprTupleGenerator{}
// Optional fields for tuple representation are only allowed at the end, and contiguously.
// Present fields are matched greedily: if the struct has five fields,
// and the last two are optional, and there's four values, then they will be mapped onto the first four fields, period.
// In theory, it would be possible to support a variety of fancier modes, configurably;
// in practice, let's not: the ROI would be atrocious:
// few people seem to want this;
// the implementation complexity would rise dramatically;
// and the next nearest substitutes for such behavior are already available, and cheap (and also sturdier).
// It would make about as much sense to support implicits as it does trailing optionals,
// which means we probably should consider that someday,
// but it's not implemented today.
func NewStructReprTupleGenerator(pkgName string, typ *schema.TypeStruct, adjCfg *AdjunctCfg) TypeGenerator {
return structReprTupleGenerator{
structGenerator{
adjCfg,
mixins.MapTraits{
PkgName: pkgName,
TypeName: string(typ.Name()),
TypeSymbol: adjCfg.TypeSymbol(typ),
},
pkgName,
typ,
},
}
}
type structReprTupleGenerator struct {
structGenerator
}
func (g structReprTupleGenerator) GetRepresentationNodeGen() NodeGenerator {
return structReprTupleReprGenerator{
g.AdjCfg,
mixins.ListTraits{
PkgName: g.PkgName,
TypeName: string(g.Type.Name()) + ".Repr",
TypeSymbol: "_" + g.AdjCfg.TypeSymbol(g.Type) + "__Repr",
},
g.PkgName,
g.Type,
}
}
type structReprTupleReprGenerator struct {
AdjCfg *AdjunctCfg
mixins.ListTraits
PkgName string
Type *schema.TypeStruct
}
func (structReprTupleReprGenerator) IsRepr() bool { return true } // hint used in some generalized templates.
func (g structReprTupleReprGenerator) EmitNodeType(w io.Writer) {
// The type is structurally the same, but will have a different set of methods.
doTemplate(`
type _{{ .Type | TypeSymbol }}__Repr _{{ .Type | TypeSymbol }}
`, w, g.AdjCfg, g)
}
func (g structReprTupleReprGenerator) EmitNodeTypeAssertions(w io.Writer) {
doTemplate(`
var _ ipld.Node = &_{{ .Type | TypeSymbol }}__Repr{}
`, w, g.AdjCfg, g)
}
func (g structReprTupleReprGenerator) EmitNodeMethodLookupByIndex(w io.Writer) {
doTemplate(`
func (n *_{{ .Type | TypeSymbol }}__Repr) LookupByIndex(idx int64) (ipld.Node, error) {
switch idx {
{{- range $i, $field := .Type.Fields }}
case {{ $i }}:
{{- if $field.IsOptional }}
if n.{{ $field | FieldSymbolLower }}.m == schema.Maybe_Absent {
return ipld.Absent, ipld.ErrNotExists{Segment: ipld.PathSegmentOfInt(idx)}
}
{{- end}}
{{- if $field.IsNullable }}
if n.{{ $field | FieldSymbolLower }}.m == schema.Maybe_Null {
return ipld.Null, nil
}
{{- end}}
{{- if $field.IsMaybe }}
return n.{{ $field | FieldSymbolLower }}.v.Representation(), nil
{{- else}}
return n.{{ $field | FieldSymbolLower }}.Representation(), nil
{{- end}}
{{- end}}
default:
return nil, schema.ErrNoSuchField{Type: nil /*TODO*/, Field: ipld.PathSegmentOfInt(idx)}
}
}
`, w, g.AdjCfg, g)
}
func (g structReprTupleReprGenerator) EmitNodeMethodLookupByNode(w io.Writer) {
doTemplate(`
func (n *_{{ .Type | TypeSymbol }}__Repr) LookupByNode(key ipld.Node) (ipld.Node, error) {
ki, err := key.AsInt()
if err != nil {
return nil, err
}
return n.LookupByIndex(ki)
}
`, w, g.AdjCfg, g)
}
func (g structReprTupleReprGenerator) EmitNodeMethodListIterator(w io.Writer) {
// DRY: much of this precalcuation about doneness is common with the map representation.
// (or at least: it is for now: the addition of support for implicits in the map representation may bamboozle that.)
// Some of the templating also experiences the `.HaveTrailingOptionals` branching,
// but not quite as much as the map representation: since we always know those come at the end
// (and in particular, once we hit one absent, we're done!), some simplifications can be made.
// The 'idx' int is what field we'll yield next.
// Note that this iterator doesn't mention fields that are absent.
// This makes things a bit trickier -- especially the 'Done' predicate,
// since it may have to do lookahead if there's any optionals at the end of the structure!
// Count how many trailing fields are optional.
// The 'Done' predicate gets more complex when in the trailing optionals.
fields := g.Type.Fields()
fieldCount := len(fields)
beginTrailingOptionalField := fieldCount
for i := fieldCount - 1; i >= 0; i-- {
if !fields[i].IsOptional() {
break
}
beginTrailingOptionalField = i
}
haveTrailingOptionals := beginTrailingOptionalField < fieldCount
// Now: finally we can get on with the actual templating.
doTemplate(`
func (n *_{{ .Type | TypeSymbol }}__Repr) ListIterator() ipld.ListIterator {
{{- if .HaveTrailingOptionals }}
end := {{ len .Type.Fields }}`+
func() string { // this next part was too silly in templates due to lack of reverse ranging.
v := "\n"
for i := fieldCount - 1; i >= beginTrailingOptionalField; i-- {
v += "\t\t\tif n." + g.AdjCfg.FieldSymbolLower(fields[i]) + ".m == schema.Maybe_Absent {\n"
v += "\t\t\t\tend = " + strconv.Itoa(i) + "\n"
v += "\t\t\t} else {\n"
v += "\t\t\t\tgoto done\n"
v += "\t\t\t}\n"
}
return v
}()+`done:
return &_{{ .Type | TypeSymbol }}__ReprListItr{n, 0, end}
{{- else}}
return &_{{ .Type | TypeSymbol }}__ReprListItr{n, 0}
{{- end}}
}
type _{{ .Type | TypeSymbol }}__ReprListItr struct {
n *_{{ .Type | TypeSymbol }}__Repr
idx int
{{if .HaveTrailingOptionals }}end int{{end}}
}
func (itr *_{{ .Type | TypeSymbol }}__ReprListItr) Next() (idx int64, v ipld.Node, err error) {
if itr.idx >= {{ len .Type.Fields }} {
return -1, nil, ipld.ErrIteratorOverread{}
}
switch itr.idx {
{{- range $i, $field := .Type.Fields }}
case {{ $i }}:
idx = int64(itr.idx)
{{- if $field.IsOptional }}
if itr.n.{{ $field | FieldSymbolLower }}.m == schema.Maybe_Absent {
return -1, nil, ipld.ErrIteratorOverread{}
}
{{- end}}
{{- if $field.IsNullable }}
if itr.n.{{ $field | FieldSymbolLower }}.m == schema.Maybe_Null {
v = ipld.Null
break
}
{{- end}}
{{- if $field.IsMaybe }}
v = itr.n.{{ $field | FieldSymbolLower}}.v.Representation()
{{- else}}
v = itr.n.{{ $field | FieldSymbolLower}}.Representation()
{{- end}}
{{- end}}
default:
panic("unreachable")
}
itr.idx++
return
}
{{- if .HaveTrailingOptionals }}
func (itr *_{{ .Type | TypeSymbol }}__ReprListItr) Done() bool {
return itr.idx >= itr.end
}
{{- else}}
func (itr *_{{ .Type | TypeSymbol }}__ReprListItr) Done() bool {
return itr.idx >= {{ len .Type.Fields }}
}
{{- end}}
`, w, g.AdjCfg, struct {
Type *schema.TypeStruct
HaveTrailingOptionals bool
}{
g.Type,
haveTrailingOptionals,
})
}
func (g structReprTupleReprGenerator) EmitNodeMethodLength(w io.Writer) {
// This is fun: it has to count down for any unset optional fields.
doTemplate(`
func (rn *_{{ .Type | TypeSymbol }}__Repr) Length() int64 {
l := {{ len .Type.Fields }}
{{- range $field := .Type.Fields }}
{{- if $field.IsOptional }}
if rn.{{ $field | FieldSymbolLower }}.m == schema.Maybe_Absent {
l--
}
{{- end}}
{{- end}}
return int64(l)
}
`, w, g.AdjCfg, g)
}
func (g structReprTupleReprGenerator) EmitNodeMethodPrototype(w io.Writer) {
emitNodeMethodPrototype_typical(w, g.AdjCfg, g)
}
func (g structReprTupleReprGenerator) EmitNodePrototypeType(w io.Writer) {
emitNodePrototypeType_typical(w, g.AdjCfg, g)
}
// --- NodeBuilder and NodeAssembler --->
func (g structReprTupleReprGenerator) GetNodeBuilderGenerator() NodeBuilderGenerator {
return structReprTupleReprBuilderGenerator{
g.AdjCfg,
mixins.ListAssemblerTraits{
PkgName: g.PkgName,
TypeName: g.TypeName,
AppliedPrefix: "_" + g.AdjCfg.TypeSymbol(g.Type) + "__Repr",
},
g.PkgName,
g.Type,
}
}
type structReprTupleReprBuilderGenerator struct {
AdjCfg *AdjunctCfg
mixins.ListAssemblerTraits
PkgName string
Type *schema.TypeStruct
}
func (structReprTupleReprBuilderGenerator) IsRepr() bool { return true } // hint used in some generalized templates.
func (g structReprTupleReprBuilderGenerator) EmitNodeBuilderType(w io.Writer) {
emitEmitNodeBuilderType_typical(w, g.AdjCfg, g)
}
func (g structReprTupleReprBuilderGenerator) EmitNodeBuilderMethods(w io.Writer) {
emitNodeBuilderMethods_typical(w, g.AdjCfg, g)
}
func (g structReprTupleReprBuilderGenerator) EmitNodeAssemblerType(w io.Writer) {
// - 'w' is the "**w**ip" pointer.
// - 'm' is the **m**aybe which communicates our completeness to the parent if we're a child assembler.
// - 'state' is what it says on the tin. this is used for the list state (the broad transitions between null, start-list, and finish are handled by 'm' for consistency with other types).
// - contrasted to the map representation, there's no 's' bitfield for what's been **s**et -- because we know things must procede in order, it would be redundant with 'f'.
// - 'f' is the **f**ocused field that will be assembled next.
//
// - 'cm' is **c**hild **m**aybe and is used for the completion message from children that aren't allowed to be nullable (for those that are, their own maybe.m is used).
// - the 'ca_*' fields embed **c**hild **a**ssemblers -- these are embedded so we can yield pointers to them without causing new allocations.
//
// Note that this textually similar to the type-level assembler, but because it embeds the repr assembler for the child types,
// it might be *significantly* different in size and memory layout in that trailing part of the struct.
doTemplate(`
type _{{ .Type | TypeSymbol }}__ReprAssembler struct {
w *_{{ .Type | TypeSymbol }}
m *schema.Maybe
state laState
f int
cm schema.Maybe
{{range $field := .Type.Fields -}}
ca_{{ $field | FieldSymbolLower }} _{{ $field.Type | TypeSymbol }}__ReprAssembler
{{end -}}
}
func (na *_{{ .Type | TypeSymbol }}__ReprAssembler) reset() {
na.state = laState_initial
na.f = 0
{{- range $field := .Type.Fields }}
na.ca_{{ $field | FieldSymbolLower }}.reset()
{{- end}}
}
`, w, g.AdjCfg, g)
}
func (g structReprTupleReprBuilderGenerator) EmitNodeAssemblerMethodBeginList(w io.Writer) {
// Future: This could do something strict with the sizehint; it currently ignores it.
doTemplate(`
func (na *_{{ .Type | TypeSymbol }}__ReprAssembler) BeginList(int64) (ipld.ListAssembler, error) {
switch *na.m {
case schema.Maybe_Value, schema.Maybe_Null:
panic("invalid state: cannot assign into assembler that's already finished")
case midvalue:
panic("invalid state: it makes no sense to 'begin' twice on the same assembler!")
}
*na.m = midvalue
{{- if .Type | MaybeUsesPtr }}
if na.w == nil {
na.w = &_{{ .Type | TypeSymbol }}{}
}
{{- end}}
return na, nil
}
`, w, g.AdjCfg, g)
}
func (g structReprTupleReprBuilderGenerator) EmitNodeAssemblerMethodAssignNull(w io.Writer) {
emitNodeAssemblerMethodAssignNull_recursive(w, g.AdjCfg, g)
}
func (g structReprTupleReprBuilderGenerator) EmitNodeAssemblerMethodAssignNode(w io.Writer) {
emitNodeAssemblerMethodAssignNode_listoid(w, g.AdjCfg, g)
}
func (g structReprTupleReprBuilderGenerator) EmitNodeAssemblerOtherBits(w io.Writer) {
g.emitListAssemblerChildTidyHelper(w)
g.emitListAssemblerChildListAssemblerMethods(w)
}
func (g structReprTupleReprBuilderGenerator) emitListAssemblerChildTidyHelper(w io.Writer) {
doTemplate(`
func (la *_{{ .Type | TypeSymbol }}__ReprAssembler) valueFinishTidy() bool {
switch la.f {
{{- range $i, $field := .Type.Fields }}
case {{ $i }}:
{{- if $field.IsMaybe }}
switch la.w.{{ $field | FieldSymbolLower }}.m {
case schema.Maybe_Value:
{{- if (MaybeUsesPtr $field.Type) }}
la.w.{{ $field | FieldSymbolLower }}.v = la.ca_{{ $field | FieldSymbolLower }}.w
{{- end}}
la.state = laState_initial
la.f++
return true
{{- else}}
switch la.cm {
case schema.Maybe_Value:
la.cm = schema.Maybe_Absent
la.state = laState_initial
la.f++
return true
{{- end}}
{{- if $field.IsNullable }}
case schema.Maybe_Null:
la.state = laState_initial
la.f++
return true
{{- end}}
default:
return false
}
{{- end}}
default:
panic("unreachable")
}
}
`, w, g.AdjCfg, g)
}
func (g structReprTupleReprBuilderGenerator) emitListAssemblerChildListAssemblerMethods(w io.Writer) {
doTemplate(`
func (la *_{{ .Type | TypeSymbol }}__ReprAssembler) AssembleValue() ipld.NodeAssembler {
switch la.state {
case laState_initial:
// carry on
case laState_midValue:
if !la.valueFinishTidy() {
panic("invalid state: AssembleValue cannot be called when still in the middle of assembling the previous value")
} // if tidy success: carry on
case laState_finished:
panic("invalid state: AssembleValue cannot be called on an assembler that's already finished")
}
if la.f >= {{ len .Type.Fields }} {
return _ErrorThunkAssembler{schema.ErrNoSuchField{Type: nil /*TODO*/, Field: ipld.PathSegmentOfInt({{ len .Type.Fields }})}}
}
la.state = laState_midValue
switch la.f {
{{- range $i, $field := .Type.Fields }}
case {{ $i }}:
{{- if $field.IsMaybe }}
la.ca_{{ $field | FieldSymbolLower }}.w = {{if not (MaybeUsesPtr $field.Type) }}&{{end}}la.w.{{ $field | FieldSymbolLower }}.v
la.ca_{{ $field | FieldSymbolLower }}.m = &la.w.{{ $field | FieldSymbolLower }}.m
{{- if $field.IsNullable }}
la.w.{{ $field | FieldSymbolLower }}.m = allowNull
{{- end}}
{{- else}}
la.ca_{{ $field | FieldSymbolLower }}.w = &la.w.{{ $field | FieldSymbolLower }}
la.ca_{{ $field | FieldSymbolLower }}.m = &la.cm
{{- end}}
return &la.ca_{{ $field | FieldSymbolLower }}
{{- end}}
default:
panic("unreachable")
}
}
`, w, g.AdjCfg, g)
// Surprisingly, the Finish method doesn't have anything to do regarding any trailing optionals:
// if they weren't assigned yet, their Maybe state is still the zero value: absent. And that's correct.
// DRY: okay, this finish component is actually identical, both textually and in terms of linking, to lists. This we should actually extract.
doTemplate(`
func (la *_{{ .Type | TypeSymbol }}__ReprAssembler) Finish() error {
switch la.state {
case laState_initial:
// carry on
case laState_midValue:
if !la.valueFinishTidy() {
panic("invalid state: Finish cannot be called when in the middle of assembling a value")
} // if tidy success: carry on
case laState_finished:
panic("invalid state: Finish cannot be called on an assembler that's already finished")
}
la.state = laState_finished
*la.m = schema.Maybe_Value
return nil
}
`, w, g.AdjCfg, g)
doTemplate(`
func (la *_{{ .Type | TypeSymbol }}__ReprAssembler) ValuePrototype(_ int64) ipld.NodePrototype {
panic("todo structbuilder tuplerepr valueprototype")
}
`, w, g.AdjCfg, g)
}