decoder [WIP]

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

decoder.go

@@ -0,0 +1,83 @@
+package ini
+
+import (
+	"bytes"
+	"io"
+	"strings"
+
+	"asciigoat.org/core"
+	"asciigoat.org/core/reflective"
+	"asciigoat.org/ini/parser"
+)
+
+const (
+	decPrefixLiteral = "ini: Decode"
+)
+
+var (
+	decINIPrefix = decPrefixLiteral[0:3]
+	decDecPrefix = decPrefixLiteral[5:]
+)
+
+// Decoder ...
+type Decoder struct {
+	io.Closer
+
+	out   *reflective.Reflection
+	p     *parser.Parser
+	queue []*token
+}
+
+// Decode ...
+func (dec *Decoder) Decode(v any) error {
+	defer dec.Close()
+
+	r, err := reflective.New(v)
+	switch e := err.(type) {
+	case *reflective.InvalidUnmarshalError:
+		// customize error
+		e.Prefix = decINIPrefix
+		e.Method = decDecPrefix
+	case *reflective.UnmarshalTypeError:
+		// customize error
+		e.Prefix = decPrefixLiteral
+	case nil:
+		// good reflection. Go!
+		dec.out = r
+		err = dec.p.Run()
+	}
+
+	return err
+}
+
+// NewDecoder creates a Decoder using the provided [io.Reader]
+// as source
+func NewDecoder(r io.Reader) *Decoder {
+	rc := core.NewReadCloser(r)
+	switch {
+	case rc == nil:
+		return nil
+	default:
+		dec := &Decoder{
+			p:      parser.NewParser(rc),
+			Closer: rc,
+		}
+
+		// callbacks
+		dec.p.OnToken = dec.parserOnToken
+		dec.p.OnError = dec.parserOnError
+
+		return dec
+	}
+}
+
+// NewDecoderBytes creates a Decoder using the provided bytes array
+// as source
+func NewDecoderBytes(b []byte) *Decoder {
+	return NewDecoder(bytes.NewReader(b))
+}
+
+// NewDecoderString creates a Decoder over a provided string of data
+func NewDecoderString(s string) *Decoder {
+	return NewDecoder(strings.NewReader(s))
+}

decoder_error.go

@@ -0,0 +1,32 @@
+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) newErrInvalidToken(t *token) *lexer.Error {
+	return newError(t.pos, t.value, "", errInvalidToken)
+}
+
+// parserOnError is the callback for lexer errors
+func (*Decoder) parserOnError(pos lexer.Position, content string, err error) error {
+	log.Printf("%s: %s %s: %q: %v", "ini", pos, "error", content, err)
+
+	return newError(pos, content, "", err)
+}

decoder_token.go

@@ -0,0 +1,144 @@
+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)
+}
+
+// queueValue extracts the value of element on the queue if the type matches.
+func (dec *Decoder) queueValue(idx int, typ parser.TokenType) (string, bool) {
+	switch {
+	case idx < 0 || idx >= len(dec.queue):
+		// out of range
+		return "", false
+	case dec.queue[idx].typ != typ:
+		// wrong type
+		return "", false
+	default:
+		// match
+		return dec.queue[idx].value, true
+	}
+}
+
+// queueReset removes all tokens from the queue
+func (dec *Decoder) queueReset() {
+	dec.queue = dec.queue[:0]
+}
+
+// queueType tells if the specified element on the queue is of the required type.
+func (dec *Decoder) queueType(idx int, typ parser.TokenType) bool {
+	_, ok := dec.queueValue(idx, typ)
+	return ok
+}
+
+// queueDepth confirms the current depth of the queue
+func (dec *Decoder) queueDepth(depth int) bool {
+	return len(dec.queue) == depth
+}
+
+// queueDepthType confirms the current depth of the queue and the type of the last
+// element.
+func (dec *Decoder) queueDepthType(depth int, typ parser.TokenType) bool {
+	if dec.queueDepth(depth) {
+		return dec.queueType(depth-1, typ)
+	}
+	return false
+}
+
+// typeOK tells if a token of the specified type is acceptable
+// at this time.
+func (dec *Decoder) typeOK(typ parser.TokenType) bool {
+	switch typ {
+	case parser.TokenSectionStart:
+		return dec.queueDepth(0)
+	case parser.TokenSectionName:
+		return dec.queueDepthType(1, parser.TokenSectionStart)
+	case parser.TokenSectionSubname:
+		return dec.queueDepthType(2, parser.TokenSectionName)
+	case parser.TokenSectionEnd:
+		return dec.queueType(1, parser.TokenSectionName)
+	case parser.TokenFieldKey:
+		return dec.queueDepth(0)
+	case parser.TokenFieldValue:
+		return dec.queueDepthType(1, parser.TokenFieldKey)
+	case parser.TokenComment:
+		panic("unreachable")
+	default:
+		return false
+	}
+}
+
+// execute is called after each acceptable token is appended to the queue
+func (dec *Decoder) execute() error {
+	if l := len(dec.queue); l > 0 {
+		// based on the type of the last element
+		switch dec.queue[l-1].typ {
+		case parser.TokenSectionEnd:
+			name1, _ := dec.queueValue(1, parser.TokenSectionName)
+			name2, ok2 := dec.queueValue(2, parser.TokenSectionSubname)
+			defer dec.queueReset()
+
+			return dec.executeSection(name1, name2, ok2)
+		case parser.TokenFieldValue:
+			key, _ := dec.queueValue(0, parser.TokenFieldKey)
+			value, _ := dec.queueValue(1, parser.TokenFieldValue)
+			defer dec.queueReset()
+
+			return dec.executeField(key, value)
+		}
+	}
+
+	return nil
+}
+
+// revive:disable:flag-parameter
+
+func (*Decoder) executeSection(key, id string, hasID bool) error {
+	// revive:enable:flag-parameter
+
+	if hasID {
+		log.Printf("%s: %s%s[%q]: %q", "ini", "", "section", key, id)
+	} else {
+		log.Printf("%s: %s%s[%q]", "ini", "", "section", key)
+	}
+
+	return nil
+}
+
+func (*Decoder) executeField(key, value string) error {
+	log.Printf("%s: %s%s[%q]: %q", "ini", "  ", "field", key, value)
+	return nil
+}
+
+// parserOnToken is the callback from the parser
+func (dec *Decoder) parserOnToken(pos lexer.Position, typ parser.TokenType, value string) error {
+	var err error
+
+	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)
+	}
+
+	return err
+}