decoder [WIP]

Signed-off-by: Alejandro Mery <amery@jpi.io>

decoder.go

@@ -0,0 +1,75 @@
+package ini
+
+import (
+	"bytes"
+	"io"
+	"strings"
+
+	"asciigoat.org/core"
+	"asciigoat.org/core/reflection"
+	"asciigoat.org/ini/parser"
+)
+
+// Decoder ...
+type Decoder[T any] struct {
+	io.Closer
+
+	out   *reflection.Reflection[T]
+	p     *parser.Parser
+	queue []*token
+}
+
+// Decode ...
+func (dec *Decoder[T]) Decode(v *T) error {
+	defer dec.Close()
+
+	r, err := reflection.New(v)
+	switch e := err.(type) {
+	case *reflection.InvalidUnmarshalError:
+		// customize error
+		e.Prefix = "ini"
+		e.Method = "Decode"
+		return e
+	case nil:
+		// good reflection. Go!
+		dec.out = r
+		return dec.p.Run()
+	default:
+		// other errors
+		panic("unreachable")
+	}
+
+}
+
+// NewDecoder creates a Decoder using the provided [io.Reader]
+// as source
+func NewDecoder[T any](r io.Reader) *Decoder[T] {
+	rc := core.NewReadCloser(r)
+	switch {
+	case rc == nil:
+		return nil
+	default:
+		dec := &Decoder[T]{
+			p:      parser.NewParser(rc),
+			Closer: rc,
+		}
+		dec.init()
+		return dec
+	}
+}
+
+func (dec *Decoder[T]) init() {
+	dec.p.OnToken = dec.parserOnToken
+	dec.p.OnError = dec.parserOnError
+}
+
+// NewDecoderBytes creates a Decoder using the provided bytes array
+// as source
+func NewDecoderBytes[T any](b []byte) *Decoder[T] {
+	return NewDecoder[T](bytes.NewReader(b))
+}
+
+// NewDecoderString creates a Decoder over a provided string of data
+func NewDecoderString[T any](s string) *Decoder[T] {
+	return NewDecoder[T](strings.NewReader(s))
+}

decoder_error.go

@@ -0,0 +1,33 @@
+package ini
+
+import (
+	"errors"
+	"log"
+
+	"asciigoat.org/core/lexer"
+)
+
+var (
+	errInvalidToken = errors.New("invalid token")
+)
+
+func newError(pos lexer.Position, content, hint string, err error) *lexer.Error {
+	return &lexer.Error{
+		Line:    pos.Line,
+		Column:  pos.Column,
+		Content: content,
+		Hint:    hint,
+		Err:     err,
+	}
+}
+func (*Decoder[T]) newErrInvalidToken(t *token) *lexer.Error {
+	return newError(t.pos, t.value, "", errInvalidToken)
+}
+
+// parserOnError is the callback for lexer errors
+func (dec *Decoder[T]) parserOnError(pos lexer.Position, content string, err error) error {
+	log.Printf("%s: %s %s: %q: %v", "ini", pos, "error:", content, err)
+
+	dec.executeFinal()
+	return newError(pos, content, "", err)
+}

decoder_token.go

@@ -0,0 +1,56 @@
+package ini
+
+import (
+	"fmt"
+	"log"
+
+	"asciigoat.org/core/lexer"
+	"asciigoat.org/ini/parser"
+)
+
+type token struct {
+	pos   lexer.Position
+	typ   parser.TokenType
+	value string
+}
+
+func (t token) String() string {
+	return fmt.Sprintf("%s %s: %q", t.pos, t.typ, t.value)
+}
+
+// typeOK tells if a token of the specified type is acceptable
+// at this time.
+func (dec *Decoder[T]) typeOK(typ parser.TokenType) bool
+
+// execute is called after each acceptable token is appended to the queue
+func (dec *Decoder[T]) execute() error
+
+// executeFinal is called after an error
+func (dec *Decoder[T]) executeFinal()
+
+// parserOnToken is the callback from the parser
+func (dec *Decoder[T]) parserOnToken(pos lexer.Position, typ parser.TokenType, value string) error {
+	var err error
+
+	log.Printf("%s: %s %s %q", "ini", pos, typ, value)
+
+	t := &token{pos, typ, value}
+	switch {
+	case typ == parser.TokenComment:
+		// ignore comments
+	case dec.typeOK(typ):
+		// acceptable token
+		dec.queue = append(dec.queue, t)
+		err = dec.execute()
+	default:
+		// unacceptable
+		err = dec.newErrInvalidToken(t)
+	}
+
+	if err != nil {
+		dec.executeFinal()
+		return err
+	}
+
+	return nil
+}