From 22b372cdb0c09cedecb6ca15864d14ad0ec604f8 Mon Sep 17 00:00:00 2001
From: Alejandro Mery <amery@jpi.io>
Date: Mon, 28 Aug 2023 23:46:05 +0000
Subject: [PATCH] parser: WIP

Signed-off-by: Alejandro Mery <amery@jpi.io>
---
 parser/lexer.go       | 58 +++++++++++++++++++++++++++++++++++++++++++
 parser/lexer_error.go | 19 ++++++++++++++
 parser/lexer_runes.go | 17 +++++++++++++
 parser/parser.go      | 38 ++++++++++++++++++++++++++++
 4 files changed, 132 insertions(+)
 create mode 100644 parser/lexer.go
 create mode 100644 parser/lexer_error.go
 create mode 100644 parser/lexer_runes.go

diff --git a/parser/lexer.go b/parser/lexer.go
new file mode 100644
index 0000000..06b5634
--- /dev/null
+++ b/parser/lexer.go
@@ -0,0 +1,58 @@
+package parser
+
+import "asciigoat.org/core/lexer"
+
+// Run parses the source
+func (p *Parser) Run() error {
+	p.setDefaults()
+
+	p.pos.Reset()
+	return lexer.Run(p.lexStart)
+}
+
+func (p *Parser) lexStart() (lexer.StateFn, error) {
+	for {
+		r, _, err := p.src.ReadRune()
+		switch {
+		case err != nil:
+			return p.emitError("", err)
+		case r == '\n':
+			// new line
+			r2, _, err := p.src.ReadRune()
+			switch {
+			case err == nil && r2 == '\r':
+				// MAC new line
+			case err == nil:
+				// UNIX new line
+				p.src.UnreadRune()
+			}
+
+			p.src.Discard()
+			p.pos.StepLine()
+		case r == '\r':
+			// new line
+			r2, _, err := p.src.ReadRune()
+			switch {
+			case err == nil && r2 == '\n':
+				// DOS new line
+			case err == nil:
+				// incomplete CRLN
+				p.src.UnreadRune()
+				return p.emitInvalidRune(r2)
+			}
+
+			p.src.Discard()
+			p.pos.StepLine()
+		case p.IsSpace(r):
+			// whitespace
+			p.src.Discard()
+			p.pos.Step()
+		case p.IsCommentStart(r):
+			// switch to comment lexer
+			p.src.UnreadRune()
+			return p.lexComment, nil
+		}
+	}
+}
+
+func (p *Parser) lexComment() (lexer.StateFn, error)
diff --git a/parser/lexer_error.go b/parser/lexer_error.go
new file mode 100644
index 0000000..afe6fab
--- /dev/null
+++ b/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)
+}
diff --git a/parser/lexer_runes.go b/parser/lexer_runes.go
new file mode 100644
index 0000000..4de3b6e
--- /dev/null
+++ b/parser/lexer_runes.go
@@ -0,0 +1,17 @@
+package parser
+
+import "unicode"
+
+func (*Parser) IsSpace(r rune) bool {
+	return unicode.IsSpace(r)
+}
+
+func (*Parser) IsCommentStart(r rune) bool {
+	// TODO: use Parser options
+	switch r {
+	case ';', '#':
+		return true
+	default:
+		return false
+	}
+}
diff --git a/parser/parser.go b/parser/parser.go
index 5d399fd..739b657 100644
--- a/parser/parser.go
+++ b/parser/parser.go
@@ -10,6 +10,44 @@ import (
 // Parser parses a dosini-style document
 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