decoder [WIP]

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

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
+}