Add a new attribute parser

go.mod

@@ -1 +1,3 @@
 module github.com/yuin/goldmark
+
+go 1.12

parser/attribute.go

@@ -0,0 +1,291 @@
+package parser
+
+import (
+	"bytes"
+	"fmt"
+	"github.com/yuin/goldmark/text"
+	"github.com/yuin/goldmark/util"
+	"strconv"
+)
+
+type attribute struct {
+	Name  string
+	Value interface{}
+}
+
+// ParseAttributes parses attributes into a map.
+// ParseAttributes returns a parsed map and true if could parse
+// attributes, otherwise nil and false.
+func ParseAttributes(reader text.Reader) (map[string]interface{}, bool) {
+	savedLine, savedPosition := reader.Position()
+	reader.SkipSpaces()
+	if reader.Peek() != '{' {
+		reader.SetPosition(savedLine, savedPosition)
+		return nil, false
+	}
+	reader.Advance(1)
+	m := map[string]interface{}{}
+	for {
+		if reader.Peek() == '}' {
+			reader.Advance(1)
+			return m, true
+		}
+		attr, ok := parseAttribute(reader)
+		if !ok {
+			reader.SetPosition(savedLine, savedPosition)
+			return nil, false
+		}
+		if attr.Name == "class" {
+			if v, ok := m["class"]; ok {
+				if _, ok2 := v.([][]byte); !ok2 {
+					m["class"] = [][]byte{v.([]byte)}
+				}
+				m["class"] = append(m["class"].([][]byte), util.StringToReadOnlyBytes(fmt.Sprintf("%v", attr.Value)))
+			} else {
+				m["class"] = util.StringToReadOnlyBytes(fmt.Sprintf("%v", attr.Value))
+			}
+		} else {
+			m[attr.Name] = attr.Value
+		}
+		reader.SkipSpaces()
+		if reader.Peek() == ',' {
+			reader.Advance(1)
+			reader.SkipSpaces()
+		}
+	}
+}
+
+func parseAttribute(reader text.Reader) (attribute, bool) {
+	reader.SkipSpaces()
+	c := reader.Peek()
+	if c == '#' || c == '.' {
+		reader.Advance(1)
+		line, _ := reader.PeekLine()
+		i := 0
+		for ; i < len(line) && !util.IsSpace(line[i]) && (!util.IsPunct(line[i]) || line[i] == '_' || line[i] == '-'); i++ {
+		}
+		name := "class"
+		if c == '#' {
+			name = "id"
+		}
+		reader.Advance(i)
+		return attribute{Name: name, Value: line[0:i]}, true
+	}
+	line, _ := reader.PeekLine()
+	c = line[0]
+	if !((c >= 'a' && c <= 'z') || (c >= 'A' && c <= 'Z') ||
+		c == '_' || c == ':') {
+		return attribute{}, false
+	}
+	i := 0
+	for ; i < len(line); i++ {
+		c := line[i]
+		if !((c >= 'a' && c <= 'z') || (c >= 'A' && c <= 'Z') ||
+			(c >= '0' && c <= '9') ||
+			c == '_' || c == ':' || c == '.' || c == '-') {
+			break
+		}
+	}
+	name := string(line[:i])
+	reader.Advance(i)
+	reader.SkipSpaces()
+	c = reader.Peek()
+	if c != '=' {
+		return attribute{}, false
+	}
+	reader.Advance(1)
+	reader.SkipSpaces()
+	value, ok := parseAttributeValue(reader)
+	if !ok {
+		return attribute{}, false
+	}
+	return attribute{Name: name, Value: value}, true
+
+}
+
+func parseAttributeValue(reader text.Reader) (interface{}, bool) {
+	reader.SkipSpaces()
+	c := reader.Peek()
+	var value interface{}
+	ok := false
+	switch c {
+	case text.EOF:
+		return attribute{}, false
+	case '{':
+		value, ok = ParseAttributes(reader)
+	case '[':
+		value, ok = parseAttributeArray(reader)
+	case '"':
+		value, ok = parseAttributeString(reader)
+	default:
+		if c == '-' || c == '+' || util.IsNumeric(c) {
+			value, ok = parseAttributeNumber(reader)
+		} else {
+			value, ok = parseAttributeOthers(reader)
+		}
+	}
+	if !ok {
+		return nil, false
+	}
+	return value, true
+
+}
+
+func parseAttributeArray(reader text.Reader) ([]interface{}, bool) {
+	reader.Advance(1) // skip [
+	ret := []interface{}{}
+	for i := 0; ; i++ {
+		c := reader.Peek()
+		comma := false
+		if i != 0 && c == ',' {
+			reader.Advance(1)
+			comma = true
+		}
+		if c == ']' {
+			if !comma {
+				reader.Advance(1)
+				return ret, true
+			}
+			return nil, false
+		}
+		reader.SkipSpaces()
+		value, ok := parseAttributeValue(reader)
+		if !ok {
+			return nil, false
+		}
+		ret = append(ret, value)
+		reader.SkipSpaces()
+	}
+}
+
+func parseAttributeString(reader text.Reader) ([]byte, bool) {
+	reader.Advance(1) // skip "
+	line, _ := reader.PeekLine()
+	i := 0
+	l := len(line)
+	var buf bytes.Buffer
+	for i < l {
+		c := line[i]
+		if c == '\\' && i != l-1 {
+			n := line[i+1]
+			switch n {
+			case '"', '/', '\\':
+				buf.WriteByte(n)
+				i += 2
+			case 'b':
+				buf.WriteString("\b")
+				i += 2
+			case 'f':
+				buf.WriteString("\f")
+				i += 2
+			case 'n':
+				buf.WriteString("\n")
+				i += 2
+			case 'r':
+				buf.WriteString("\r")
+				i += 2
+			case 't':
+				buf.WriteString("\t")
+				i += 2
+			default:
+				buf.WriteByte('\\')
+				i++
+			}
+			continue
+		}
+		if c == '"' {
+			reader.Advance(i + 1)
+			return buf.Bytes(), true
+		}
+		buf.WriteByte(c)
+		i++
+	}
+	return nil, false
+}
+
+func scanAttributeDecimal(reader text.Reader, w *bytes.Buffer) {
+	for {
+		c := reader.Peek()
+		if util.IsNumeric(c) {
+			w.WriteByte(c)
+		} else {
+			return
+		}
+		reader.Advance(1)
+	}
+}
+
+func parseAttributeNumber(reader text.Reader) (float64, bool) {
+	sign := 1
+	c := reader.Peek()
+	if c == '-' {
+		sign = -1
+		reader.Advance(1)
+	} else if c == '+' {
+		reader.Advance(1)
+	}
+	var buf bytes.Buffer
+	if !util.IsNumeric(reader.Peek()) {
+		return 0, false
+	}
+	scanAttributeDecimal(reader, &buf)
+	if buf.Len() == 0 {
+		return 0, false
+	}
+	c = reader.Peek()
+	if c == '.' {
+		buf.WriteByte(c)
+		reader.Advance(1)
+		scanAttributeDecimal(reader, &buf)
+	}
+	c = reader.Peek()
+	if c == 'e' || c == 'E' {
+		buf.WriteByte(c)
+		reader.Advance(1)
+		c = reader.Peek()
+		if c == '-' || c == '+' {
+			buf.WriteByte(c)
+			reader.Advance(1)
+		}
+		scanAttributeDecimal(reader, &buf)
+	}
+	f, err := strconv.ParseFloat(buf.String(), 10)
+	if err != nil {
+		return 0, false
+	}
+	return float64(sign) * f, true
+}
+
+var bytesTrue = []byte("true")
+var bytesFalse = []byte("false")
+var bytesNull = []byte("null")
+
+func parseAttributeOthers(reader text.Reader) (interface{}, bool) {
+	line, _ := reader.PeekLine()
+	c := line[0]
+	if !((c >= 'a' && c <= 'z') || (c >= 'A' && c <= 'Z') ||
+		c == '_' || c == ':') {
+		return nil, false
+	}
+	i := 0
+	for ; i < len(line); i++ {
+		c := line[i]
+		if !((c >= 'a' && c <= 'z') || (c >= 'A' && c <= 'Z') ||
+			(c >= '0' && c <= '9') ||
+			c == '_' || c == ':' || c == '.' || c == '-') {
+			break
+		}
+	}
+	value := line[:i]
+	reader.Advance(i)
+	if bytes.Equal(value, bytesTrue) {
+		return true, true
+	}
+	if bytes.Equal(value, bytesFalse) {
+		return false, true
+	}
+	if bytes.Equal(value, bytesNull) {
+		return nil, true
+	}
+	return value, true
+}