1 files changed, 311 insertions, 0 deletions
diff --git a/asspb.go b/asspb.go
new file mode 100644
index 0000000..9f2c506
--- /dev/null
+++ b/asspb.go
@@ -0,0 +1,311 @@
+// Me: Mom can we have textproto?
+//
+// Mom: no we have textproto at home
+//
+// textproto at home:
+package asspb
+
+import (
+	"bytes"
+	"encoding/json"
+	"fmt"
+	"regexp"
+	"strconv"
+	"unicode/utf8"
+)
+
+func appendAnyRepeated(prev any, new ...any) []any {
+	if prev == nil {
+		return new
+	}
+	if prevList, ok := prev.([]any); ok {
+		return append(prevList, new...)
+	}
+	return append([]any{prev}, new...)
+}
+
+func appendAny(prev any, new any) any {
+	if prev == nil {
+		return new
+	}
+	return appendAnyRepeated(prev, new)
+}
+
+type parser struct {
+	data []byte
+	i    int
+}
+
+var spaceRE = regexp.MustCompile(`^([[:space:]\p{Zs}]|#[^\n]*)*`)
+
+func (p *parser) skipSpace() {
+	p.i += len(spaceRE.Find(p.data[p.i:]))
+}
+
+func (p *parser) parseLit(s string) bool {
+	p.skipSpace()
+	if len(p.data[p.i:]) >= len(s) && string(p.data[p.i:p.i+len(s)]) == s {
+		p.i += len(s)
+		return true
+	}
+	return false
+}
+
+var numRE = regexp.MustCompile(`^-?(0x[0-9a-fA-F]+|([0-9]+(\.[0-9]*)?|\.[0-9]+)(e-?[0-9]+)?)`)
+
+func (p *parser) parseNum() (any, bool) {
+	p.skipSpace()
+	numBytes := numRE.Find(p.data[p.i:])
+	if numBytes == nil {
+		return nil, false
+	}
+	if bytes.ContainsAny(numBytes, ".e") {
+		n, err := strconv.ParseFloat(string(numBytes), 64)
+		if err != nil {
+			return nil, false
+		}
+		p.i += len(numBytes)
+		return n, true
+	}
+	if b, ok := bytes.CutPrefix(numBytes, []byte("0x")); ok {
+		n, err := strconv.ParseInt(string(b), 16, 64)
+		if err != nil {
+			return nil, false
+		}
+		p.i += len(numBytes)
+		return n, true
+	}
+	n, err := strconv.ParseInt(string(numBytes), 10, 64)
+	if err != nil {
+		return nil, false
+	}
+	p.i += len(numBytes)
+	return n, true
+}
+
+var escapesRE = regexp.MustCompile(`\\(.|[0-7]{3}|x[0-9a-fA-F]{2}|u[0-9a-fA-F]{4}|U[0-9a-fA-F]{8})`)
+
+func init() {
+	escapesRE.Longest()
+}
+
+func unescape(idx int, rawStr []byte) (string, error) {
+	var err error
+	escaped := escapesRE.ReplaceAllFunc(rawStr, func(escape []byte) []byte {
+		switch string(escape) {
+		case `\'`:
+			return []byte("'")
+		case `\"`:
+			return []byte(`"`)
+		case `\\`:
+			return []byte(`\`)
+		case `\a`:
+			return []byte("\a")
+		case `\b`:
+			return []byte("\b")
+		case `\f`:
+			return []byte("\f")
+		case `\n`:
+			return []byte("\n")
+		case `\r`:
+			return []byte("\r")
+		case `\t`:
+			return []byte("\t")
+		case `\v`:
+			return []byte("\v")
+		}
+		if bytes.HasPrefix(escape, []byte(`\x`)) || bytes.HasPrefix(escape, []byte(`\u`)) || bytes.HasPrefix(escape, []byte(`\U`)) {
+			var n int64
+			if n, err = strconv.ParseInt(string(escape[2:]), 16, 32); err != nil {
+				err = fmt.Errorf("%d: syntax error: invalid hex escape %q: %s", idx, escape, err)
+				return nil
+			}
+			return utf8.AppendRune(nil, rune(n))
+		}
+		if len(escape) != 4 {
+			err = fmt.Errorf("%d: syntax error: invalid string escape %q", idx, escape)
+			return nil
+		}
+		var n int64
+		if n, err = strconv.ParseInt(string(escape[1:]), 8, 32); err != nil {
+			err = fmt.Errorf("%d: syntax error: invalid string escape %q", idx, escape)
+			return nil
+		}
+		return utf8.AppendRune(nil, rune(n))
+	})
+	if err != nil {
+		return "", err
+	}
+	return string(escaped), nil
+}
+
+var stringRE = regexp.MustCompile(`^(([^'\\]|\\.)*)'`)
+
+func (p *parser) parseString() (string, error) {
+	p.skipSpace()
+	rawStr := stringRE.FindSubmatch(p.data[p.i:])
+	if rawStr == nil {
+		return "", fmt.Errorf("%d: syntax error: invalid string", p.i)
+	}
+	s, err := unescape(p.i, rawStr[1])
+	if err != nil {
+		return "", err
+	}
+	p.i += len(rawStr[0])
+	return s, nil
+}
+
+var doubleStringRE = regexp.MustCompile(`^(([^"\\]|\\.)*)"`)
+
+func (p *parser) parseDoubleString() (string, error) {
+	p.skipSpace()
+	rawStr := doubleStringRE.FindSubmatch(p.data[p.i:])
+	if rawStr == nil {
+		return "", fmt.Errorf("%d: syntax error: invalid string", p.i)
+	}
+	s, err := unescape(p.i, rawStr[1])
+	if err != nil {
+		return "", err
+	}
+	p.i += len(rawStr[0])
+	return s, nil
+}
+
+var fieldRE = regexp.MustCompile(`^[a-zA-Z_][a-zA-Z_0-9]*`)
+
+func (p *parser) parseField() ([]byte, error) {
+	p.skipSpace()
+	fieldName := fieldRE.Find(p.data[p.i:])
+	if fieldName == nil {
+		return nil, fmt.Errorf("%d: syntax error: expecting field name", p.i)
+	}
+	p.i += len(fieldName)
+	return fieldName, nil
+}
+
+func (p *parser) parseMessage() (map[string]any, error) {
+	m := make(map[string]any)
+	for {
+		if p.parseLit("}") {
+			return m, nil
+		}
+		if err := p.parseFieldVal(m); err != nil {
+			return nil, err
+		}
+	}
+}
+
+func (p *parser) parseVal() (any, error) {
+	var (
+		val any
+		err error
+	)
+	switch {
+	case p.parseLit("{"):
+		val, err = p.parseMessage()
+	case p.parseLit("["):
+		val, err = p.parseList()
+	case p.parseLit("'"):
+		val, err = p.parseString()
+	case p.parseLit(`"`):
+		val, err = p.parseDoubleString()
+	case p.parseLit("true"), p.parseLit("yes"), p.parseLit("on"):
+		val = true
+	case p.parseLit("false"), p.parseLit("no"), p.parseLit("off"):
+		val = false
+	default:
+		var ok bool
+		val, ok = p.parseNum()
+		if !ok {
+			return nil, fmt.Errorf("%d: syntax error: expecting field value", p.i)
+		}
+	}
+	return val, err
+}
+
+func (p *parser) parseList() ([]any, error) {
+	l := []any{}
+	for i := 0; ; i++ {
+		if p.parseLit("]") {
+			return l, nil
+		}
+		if i > 0 {
+			if !p.parseLit(",") {
+				return nil, fmt.Errorf("%d: syntax error: expecting comma", p.i)
+			}
+			if p.parseLit("]") { // allow trailing comma
+				return l, nil
+			}
+		}
+		val, err := p.parseVal()
+		if err != nil {
+			return nil, err
+		}
+		l = append(l, val)
+	}
+}
+
+func (p *parser) parseFieldVal(out map[string]any) error {
+	field, err := p.parseField()
+	if err != nil {
+		return err
+	}
+	var val any
+	switch {
+	case p.parseLit("{"):
+		if val, err = p.parseMessage(); err != nil {
+			return err
+		}
+	case p.parseLit("["):
+		val, err := p.parseList()
+		if err != nil {
+			return err
+		}
+		out[string(field)] = appendAnyRepeated(out[string(field)], val...)
+		return nil
+	case p.parseLit(":"):
+		if val, err = p.parseVal(); err != nil {
+			return err
+		}
+		if l, ok := val.([]any); ok {
+			out[string(field)] = appendAnyRepeated(out[string(field)], l...)
+			return nil
+		}
+	default:
+		return fmt.Errorf("%d: syntax error: expecting colon", p.i)
+	}
+	out[string(field)] = appendAny(out[string(field)], val)
+	return nil
+}
+
+func (p *parser) parse() (map[string]any, error) {
+	m := make(map[string]any)
+	for {
+		p.skipSpace()
+		if p.i == len(p.data) {
+			return m, nil
+		}
+		if err := p.parseFieldVal(m); err != nil {
+			return nil, err
+		}
+	}
+}
+
+// Unmarshal parses an asspb message and writes the result into v. Unmarshal
+// internally calls json.Unmarshal for the reflection-based struct unpacking, so
+// feel free to use json struct tags on v, or implement UnmarshalJSON to control
+// the unmarshalling behavior.
+func Unmarshal(data []byte, v any) error {
+	p := &parser{data: data}
+	m, err := p.parse()
+	if err != nil {
+		return err
+	}
+	fmt.Printf("%s: %v\n", data, m)
+	jsonBytes, err := json.Marshal(m)
+	if err != nil {
+		return err
+	}
+	fmt.Printf("%s: %s\n", data, jsonBytes)
+	return json.Unmarshal(jsonBytes, v)
+}