parser: WIP

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

go.mod

@@ -5,7 +5,7 @@ go 1.19
 replace asciigoat.org/core => ../core
 
 require (
-	asciigoat.org/core v0.3.2
+	asciigoat.org/core v0.3.4
 	github.com/mgechev/revive v1.3.3
 )
 

parser/lexer.go

@@ -8,6 +8,8 @@ import (
 
 // Run parses the source
 func (p *Parser) Run() error {
+	p.setDefaults()
+
 	p.pos.Reset()
 	return lexer.Run(p.lexStart)
 }
@@ -18,27 +20,74 @@ func (p *Parser) lexStart() (lexer.StateFn, error) {
 		switch {
 		case err != nil:
 			// read error
-			log.Printf("%s: %s: %s", p.pos, "error", err)
-			return nil, err
+			return p.emitError("", err)
 		case IsNewLine(r):
 			// new line
-			p.src.UnreadRune()
-			p.lexNewLine()
-
+			p.lexNewLine(r)
 			p.src.Discard()
 			p.pos.StepLine()
 		case IsSpace(r):
 			// whitespace
 			p.src.Discard()
 			p.pos.Step()
-		default:
-			// token
+		case IsCommentStart(r):
+			// switch to comment lexer
 			p.src.UnreadRune()
-			return p.lexToken, nil
+			return p.lexComment, nil
+		case IsSectionStart(r):
+			// section
+			p.src.Discard()
+			p.pos.Step()
+			return p.lexSectionStart, nil
+		default:
+			// entry
+			p.src.UnreadRune()
+			return p.lexEntryStart, nil
 		}
 	}
 }
 
+func (p *Parser) lexNewLine(r1 rune) {
+	// r1 is warrantied to be either \n or \r
+	r2, _, err := p.src.ReadRune()
+
+	switch r1 {
+	case '\r':
+		switch {
+		case r2 == '\n':
+			// CR LN
+		case err == nil:
+			// CR
+			p.src.UnreadRune()
+		default:
+			// CR EOF
+		}
+	case '\n':
+		switch {
+		case r2 == '\r':
+			// LN CR
+		case err == nil:
+			// LN
+			p.src.UnreadRune()
+		default:
+			// LN EOF
+		}
+	default:
+		panic("unreachable")
+	}
+}
+
+func (p *Parser) lexComment() (lexer.StateFn, error) {
+	// until the end of the line
+	p.src.AcceptAll(IsNotNewLine)
+
+	err := p.OnComment(p.pos, p.src.Emit())
+	return p.lexStart, err
+}
+
+func (*Parser) lexSectionStart() (lexer.StateFn, error) { return nil, nil }
+func (*Parser) lexEntryStart() (lexer.StateFn, error)   { return nil, nil }
+
 func (p *Parser) lexToken() (lexer.StateFn, error) {
 	p.src.AcceptAll(IsNotSpace)
 
@@ -48,22 +97,3 @@ func (p *Parser) lexToken() (lexer.StateFn, error) {
 
 	return p.lexStart, nil
 }
-
-func (p *Parser) lexNewLine() {
-	// r1 is warrantied to be either \n or \r
-	r1, _, _ := p.src.ReadRune()
-	r2, _, err := p.src.ReadRune()
-
-	switch {
-	case r1 == '\r' && r2 == '\n':
-		// CR LN
-	case r1 == '\r' && err == nil:
-		// CR
-		p.src.UnreadRune()
-	case r2 == '\r':
-		// LN CR
-	case err == nil:
-		// LN
-		p.src.UnreadRune()
-	}
-}

parser/lexer_error.go

@@ -0,0 +1,19 @@
+package parser
+
+import "asciigoat.org/core/lexer"
+
+func (p *Parser) emitError(content string, err error) (lexer.StateFn, error) {
+	err2 := p.OnError(p.pos, content, err)
+	switch {
+	case err2 != nil:
+		// return wrapped error
+		return nil, err2
+	default:
+		// return original error
+		return nil, err
+	}
+}
+
+func (p *Parser) emitInvalidRune(r rune) (lexer.StateFn, error) {
+	return p.emitError(string([]rune{r}), lexer.ErrUnacceptableRune)
+}

parser/lexer_runes.go

@@ -11,4 +11,10 @@ var (
 	IsNotNewLine = lexer.NewIsNot(IsNewLine)
 	// IsNotSpace tells if a rune is anything other than whitespace
 	IsNotSpace = lexer.NewIsNot(IsSpace)
+
+	IsCommentStart = lexer.NewIsIn(";#")
 )
+
+func IsSectionStart(r rune) bool {
+	return r == '['
+}

parser/parser.go

@@ -12,6 +12,42 @@ type Parser struct {
 	src *lexer.Reader
 
 	pos lexer.Position
+
+	OnSection func(pos lexer.Position, name, subname string, hasSubname bool) error
+	OnField   func(pos lexer.Position, key, value string) error
+	OnComment func(pos lexer.Position, comment string) error
+	OnError   func(pos lexer.Position, content string, err error) error
+}
+
+func defaultOnSection(_ lexer.Position, _, _ string, _ bool) error { return nil }
+func defaultOnField(_ lexer.Position, _, _ string) error           { return nil }
+func defaultOnComment(_ lexer.Position, _ string) error            { return nil }
+
+func defaultOnError(pos lexer.Position, content string, err error) error {
+	return &lexer.Error{
+		Line:    pos.Line,
+		Column:  pos.Column,
+		Content: content,
+		Err:     err,
+	}
+}
+
+func (p *Parser) setDefaults() {
+	if p.OnSection == nil {
+		p.OnSection = defaultOnSection
+	}
+
+	if p.OnField == nil {
+		p.OnField = defaultOnField
+	}
+
+	if p.OnComment == nil {
+		p.OnComment = defaultOnComment
+	}
+
+	if p.OnError == nil {
+		p.OnError = defaultOnError
+	}
 }
 
 // NewParser creates a dosini-style parser using