1 files changed, 107 insertions, 0 deletions
diff --git a/markdown/ast.go b/markdown/ast.go
new file mode 100644
index 0000000..c45eb1e
--- /dev/null
+++ b/markdown/ast.go
@@ -0,0 +1,107 @@
+package markdown
+
+import (
+	"encoding/json"
+	"errors"
+	"fmt"
+	"html/template"
+	"strings"
+)
+
+var ErrUnkownLexType = errors.New("unkown lex type")
+
+type block interface {
+	Eval() (template.HTML, *ParseError)
+}
+
+type tree struct {
+	blocks []block
+}
+
+func (t *tree) Eval() (template.HTML, *ParseError) {
+	var content template.HTML
+	for _, c := range t.blocks {
+		ct, err := c.Eval()
+		if err != nil {
+			return "", err
+		}
+		content += ct
+	}
+	return content, nil
+}
+
+func (t *tree) String() string {
+	b, _ := json.MarshalIndent(t, "", "  ")
+	return string(b)
+}
+
+func ast(lxs *lexers) (*tree, *ParseError) {
+	tr := new(tree)
+	newLine := true
+	for lxs.Next() {
+		b, err := getBlock(lxs, newLine)
+		if err != nil {
+			return nil, err
+		}
+		if b != nil {
+			tr.blocks = append(tr.blocks, b)
+		}
+		if !lxs.Finished() {
+			newLine = lxs.Current().Type == lexerBreak
+		}
+	}
+	return tr, nil
+}
+
+func getBlock(lxs *lexers, newLine bool) (block, *ParseError) {
+	var b block
+	var err *ParseError
+	switch lxs.Current().Type {
+	case lexerHeader:
+		if !newLine {
+			b, err = paragraph(lxs, false)
+		} else {
+			b, err = header(lxs)
+		}
+	case lexerExternal:
+		if newLine && lxs.Current().Value == "![" {
+			b, err = external(lxs)
+		} else {
+			b, err = paragraph(lxs, false)
+		}
+	case lexerQuote:
+		if newLine {
+			b, err = quote(lxs)
+		} else {
+			b, err = paragraph(lxs, false)
+		}
+	case lexerList:
+		if newLine {
+			b, err = list(lxs)
+		} else {
+			b, err = paragraph(lxs, false)
+		}
+	case lexerCode:
+		if !newLine && len(lxs.Current().Value) == 3 {
+			return nil, &ParseError{lxs: *lxs, internal: ErrInvalidCodeBlockPosition}
+		}
+		if len(lxs.Current().Value) == 1 {
+			b, err = paragraph(lxs, false)
+		} else {
+			b, err = code(lxs)
+		}
+	case lexerLiteral, lexerModifier:
+		b, err = paragraph(lxs, false)
+	case lexerBreak: // do nothing
+	default:
+		err = &ParseError{
+			lxs:      *lxs,
+			internal: errors.Join(ErrUnkownLexType, fmt.Errorf("type received: %s", lxs.Current().Type)),
+		}
+	}
+	return b, err
+}
+
+func trimSpace(s template.HTML) template.HTML {
+	return template.HTML(strings.TrimSpace(string(s)))
+}