Move the parser back + handle utf16 files (#4533)

parser/parser.go

@@ -0,0 +1,327 @@
+package parser
+
+import (
+	"bufio"
+	"bytes"
+	"errors"
+	"fmt"
+	"io"
+	"strconv"
+	"strings"
+	"unicode"
+)
+
+type File struct {
+	Commands []Command
+}
+
+func (f File) String() string {
+	var sb strings.Builder
+	for _, cmd := range f.Commands {
+		fmt.Fprintln(&sb, cmd.String())
+	}
+
+	return sb.String()
+}
+
+type Command struct {
+	Name string
+	Args string
+}
+
+func (c Command) String() string {
+	var sb strings.Builder
+	switch c.Name {
+	case "model":
+		fmt.Fprintf(&sb, "FROM %s", c.Args)
+	case "license", "template", "system", "adapter":
+		fmt.Fprintf(&sb, "%s %s", strings.ToUpper(c.Name), quote(c.Args))
+	case "message":
+		role, message, _ := strings.Cut(c.Args, ": ")
+		fmt.Fprintf(&sb, "MESSAGE %s %s", role, quote(message))
+	default:
+		fmt.Fprintf(&sb, "PARAMETER %s %s", c.Name, quote(c.Args))
+	}
+
+	return sb.String()
+}
+
+type state int
+
+const (
+	stateNil state = iota
+	stateName
+	stateValue
+	stateParameter
+	stateMessage
+	stateComment
+)
+
+var (
+	errMissingFrom        = errors.New("no FROM line")
+	errInvalidMessageRole = errors.New("message role must be one of \"system\", \"user\", or \"assistant\"")
+	errInvalidCommand     = errors.New("command must be one of \"from\", \"license\", \"template\", \"system\", \"adapter\", \"parameter\", or \"message\"")
+)
+
+func ParseFile(r io.Reader) (*File, error) {
+	var cmd Command
+	var curr state
+	var b bytes.Buffer
+	var role string
+
+	var lineCount int
+	var linePos int
+
+	var utf16 bool
+
+	var f File
+
+	br := bufio.NewReader(r)
+	for {
+		r, _, err := br.ReadRune()
+		if errors.Is(err, io.EOF) {
+			break
+		} else if err != nil {
+			return nil, err
+		}
+
+		// the utf16 byte order mark will be read as "unreadable" by ReadRune()
+		if isUnreadable(r) && lineCount == 0 && linePos == 0 {
+			utf16 = true
+			continue
+		}
+
+		// skip the second byte if we're reading utf16
+		if utf16 && r == 0 {
+			continue
+		}
+
+		next, r, err := parseRuneForState(r, curr)
+		if errors.Is(err, io.ErrUnexpectedEOF) {
+			return nil, fmt.Errorf("%w: %s", err, b.String())
+		} else if err != nil {
+			return nil, err
+		}
+
+		if isNewline(r) {
+			lineCount++
+			linePos = 0
+		} else {
+			linePos++
+		}
+
+		// process the state transition, some transitions need to be intercepted and redirected
+		if next != curr {
+			switch curr {
+			case stateName:
+				if !isValidCommand(b.String()) {
+					return nil, errInvalidCommand
+				}
+
+				// next state sometimes depends on the current buffer value
+				switch s := strings.ToLower(b.String()); s {
+				case "from":
+					cmd.Name = "model"
+				case "parameter":
+					// transition to stateParameter which sets command name
+					next = stateParameter
+				case "message":
+					// transition to stateMessage which validates the message role
+					next = stateMessage
+					fallthrough
+				default:
+					cmd.Name = s
+				}
+			case stateParameter:
+				cmd.Name = b.String()
+			case stateMessage:
+				if !isValidMessageRole(b.String()) {
+					return nil, errInvalidMessageRole
+				}
+
+				role = b.String()
+			case stateComment, stateNil:
+				// pass
+			case stateValue:
+				s, ok := unquote(b.String())
+				if !ok || isSpace(r) {
+					if _, err := b.WriteRune(r); err != nil {
+						return nil, err
+					}
+
+					continue
+				}
+
+				if role != "" {
+					s = role + ": " + s
+					role = ""
+				}
+
+				cmd.Args = s
+				f.Commands = append(f.Commands, cmd)
+			}
+
+			b.Reset()
+			curr = next
+		}
+
+		if strconv.IsPrint(r) {
+			if _, err := b.WriteRune(r); err != nil {
+				return nil, err
+			}
+		}
+	}
+
+	// flush the buffer
+	switch curr {
+	case stateComment, stateNil:
+		// pass; nothing to flush
+	case stateValue:
+		s, ok := unquote(b.String())
+		if !ok {
+			return nil, io.ErrUnexpectedEOF
+		}
+
+		if role != "" {
+			s = role + ": " + s
+		}
+
+		cmd.Args = s
+		f.Commands = append(f.Commands, cmd)
+	default:
+		return nil, io.ErrUnexpectedEOF
+	}
+
+	for _, cmd := range f.Commands {
+		if cmd.Name == "model" {
+			return &f, nil
+		}
+	}
+
+	return nil, errMissingFrom
+}
+
+func parseRuneForState(r rune, cs state) (state, rune, error) {
+	switch cs {
+	case stateNil:
+		switch {
+		case r == '#':
+			return stateComment, 0, nil
+		case isSpace(r), isNewline(r):
+			return stateNil, 0, nil
+		default:
+			return stateName, r, nil
+		}
+	case stateName:
+		switch {
+		case isAlpha(r):
+			return stateName, r, nil
+		case isSpace(r):
+			return stateValue, 0, nil
+		default:
+			return stateNil, 0, errInvalidCommand
+		}
+	case stateValue:
+		switch {
+		case isNewline(r):
+			return stateNil, r, nil
+		case isSpace(r):
+			return stateNil, r, nil
+		default:
+			return stateValue, r, nil
+		}
+	case stateParameter:
+		switch {
+		case isAlpha(r), isNumber(r), r == '_':
+			return stateParameter, r, nil
+		case isSpace(r):
+			return stateValue, 0, nil
+		default:
+			return stateNil, 0, io.ErrUnexpectedEOF
+		}
+	case stateMessage:
+		switch {
+		case isAlpha(r):
+			return stateMessage, r, nil
+		case isSpace(r):
+			return stateValue, 0, nil
+		default:
+			return stateNil, 0, io.ErrUnexpectedEOF
+		}
+	case stateComment:
+		switch {
+		case isNewline(r):
+			return stateNil, 0, nil
+		default:
+			return stateComment, 0, nil
+		}
+	default:
+		return stateNil, 0, errors.New("")
+	}
+}
+
+func quote(s string) string {
+	if strings.Contains(s, "\n") || strings.HasPrefix(s, " ") || strings.HasSuffix(s, " ") {
+		if strings.Contains(s, "\"") {
+			return `"""` + s + `"""`
+		}
+
+		return `"` + s + `"`
+	}
+
+	return s
+}
+
+func unquote(s string) (string, bool) {
+	// TODO: single quotes
+	if len(s) >= 3 && s[:3] == `"""` {
+		if len(s) >= 6 && s[len(s)-3:] == `"""` {
+			return s[3 : len(s)-3], true
+		}
+
+		return "", false
+	}
+
+	if len(s) >= 1 && s[0] == '"' {
+		if len(s) >= 2 && s[len(s)-1] == '"' {
+			return s[1 : len(s)-1], true
+		}
+
+		return "", false
+	}
+
+	return s, true
+}
+
+func isAlpha(r rune) bool {
+	return r >= 'a' && r <= 'z' || r >= 'A' && r <= 'Z'
+}
+
+func isNumber(r rune) bool {
+	return r >= '0' && r <= '9'
+}
+
+func isSpace(r rune) bool {
+	return r == ' ' || r == '\t'
+}
+
+func isNewline(r rune) bool {
+	return r == '\r' || r == '\n'
+}
+
+func isUnreadable(r rune) bool {
+	return r == unicode.ReplacementChar
+}
+
+func isValidMessageRole(role string) bool {
+	return role == "system" || role == "user" || role == "assistant"
+}
+
+func isValidCommand(cmd string) bool {
+	switch strings.ToLower(cmd) {
+	case "from", "license", "template", "system", "adapter", "parameter", "message":
+		return true
+	default:
+		return false
+	}
+}