parser: tidy up parameter/message parsing

This change addresses how parameters and messages are handled while parsing a Modelfile.
Currently a `MESSAGE` command creates a string that looks like "<role>: <message>" which
then has to be re-parsed, and `PARAMETER` ends up being the default data type which makes
it difficult to add other multi-part commands.

This change introduces a Message and a Parameter type which properly handle properties
such as the role and the name of the parameter.

parser/parser.go

@@ -62,14 +62,15 @@ func (f Modelfile) CreateRequest(relativeDir string) (*api.CreateRequest, error)
 	for _, c := range f.Commands {
 		switch c.Name {
 		case "model":
-			path, err := expandPath(c.Args, relativeDir)
+			name := c.Args.(string)
+			path, err := expandPath(name, relativeDir)
 			if err != nil {
 				return nil, err
 			}
 
 			digestMap, err := fileDigestMap(path)
 			if errors.Is(err, os.ErrNotExist) {
-				req.From = c.Args
+				req.From = name
 				continue
 			} else if err != nil {
 				return nil, err
@@ -83,7 +84,8 @@ func (f Modelfile) CreateRequest(relativeDir string) (*api.CreateRequest, error)
 				}
 			}
 		case "adapter":
-			path, err := expandPath(c.Args, relativeDir)
+			adapter := c.Args.(string)
+			path, err := expandPath(adapter, relativeDir)
 			if err != nil {
 				return nil, err
 			}
@@ -95,21 +97,25 @@ func (f Modelfile) CreateRequest(relativeDir string) (*api.CreateRequest, error)
 
 			req.Adapters = digestMap
 		case "template":
-			req.Template = c.Args
+			template := c.Args.(string)
+			req.Template = template
 		case "system":
-			req.System = c.Args
+			system := c.Args.(string)
+			req.System = system
 		case "license":
-			licenses = append(licenses, c.Args)
+			license := c.Args.(string)
+			licenses = append(licenses, license)
 		case "message":
-			role, msg, _ := strings.Cut(c.Args, ": ")
-			messages = append(messages, api.Message{Role: role, Content: msg})
-		default:
+			msg := c.Args.(*Message)
+			messages = append(messages, api.Message{Role: msg.Role, Content: msg.Content})
+		case "parameter":
 			if slices.Contains(deprecatedParameters, c.Name) {
-				fmt.Printf("warning: parameter %s is deprecated\n", c.Name)
+				fmt.Printf("warning: parameter '%s' is deprecated\n", c.Name)
 				break
 			}
 
-			ps, err := api.FormatParams(map[string][]string{c.Name: {c.Args}})
+			param := c.Args.(*Parameter)
+			ps, err := api.FormatParams(map[string][]string{param.Name: {param.Value}})
 			if err != nil {
 				return nil, err
 			}
@@ -123,6 +129,8 @@ func (f Modelfile) CreateRequest(relativeDir string) (*api.CreateRequest, error)
 					params[k] = v
 				}
 			}
+		default:
+			return nil, fmt.Errorf("warning: unknown command '%s'", c.Name)
 		}
 	}
 
@@ -312,7 +320,17 @@ func filesForModel(path string) ([]string, error) {
 
 type Command struct {
 	Name string
-	Args string
+	Args any
+}
+
+type Parameter struct {
+	Name  string
+	Value string
+}
+
+type Message struct {
+	Role    string
+	Content string
 }
 
 func (c Command) String() string {
@@ -321,12 +339,16 @@ func (c Command) String() string {
 	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))
+		data := c.Args.(string)
+		fmt.Fprintf(&sb, "%s %s", strings.ToUpper(c.Name), quote(data))
 	case "message":
-		role, message, _ := strings.Cut(c.Args, ": ")
-		fmt.Fprintf(&sb, "MESSAGE %s %s", role, quote(message))
+		data := c.Args.(*Message)
+		fmt.Fprintf(&sb, "MESSAGE %s %s", data.Role, quote(data.Content))
+	case "parameter":
+		data := c.Args.(*Parameter)
+		fmt.Fprintf(&sb, "PARAMETER %s %s", data.Name, quote(data.Value))
 	default:
-		fmt.Fprintf(&sb, "PARAMETER %s %s", c.Name, quote(c.Args))
+		fmt.Printf("unknown command '%s'\n", c.Name)
 	}
 
 	return sb.String()
@@ -366,7 +388,6 @@ func ParseFile(r io.Reader) (*Modelfile, error) {
 	var curr state
 	var currLine int = 1
 	var b bytes.Buffer
-	var role string
 
 	var f Modelfile
 
@@ -413,6 +434,7 @@ func ParseFile(r io.Reader) (*Modelfile, error) {
 				case "parameter":
 					// transition to stateParameter which sets command name
 					next = stateParameter
+					cmd.Name = s
 				case "message":
 					// transition to stateMessage which validates the message role
 					next = stateMessage
@@ -421,16 +443,37 @@ func ParseFile(r io.Reader) (*Modelfile, error) {
 					cmd.Name = s
 				}
 			case stateParameter:
-				cmd.Name = b.String()
+				s, ok := unquote(strings.TrimSpace(b.String()))
+				if !ok || isSpace(r) {
+					if _, err := b.WriteRune(r); err != nil {
+						return nil, err
+					}
+
+					continue
+				}
+				cmd.Args = &Parameter{
+					Name: s,
+				}
 			case stateMessage:
-				if !isValidMessageRole(b.String()) {
+				s, ok := unquote(strings.TrimSpace(b.String()))
+				if !ok || isSpace(r) {
+					if _, err := b.WriteRune(r); err != nil {
+						return nil, err
+					}
+
+					continue
+				}
+
+				if !isValidMessageRole(s) {
 					return nil, &ParserError{
 						LineNumber: currLine,
 						Msg:        errInvalidMessageRole.Error(),
 					}
 				}
 
-				role = b.String()
+				cmd.Args = &Message{
+					Role: s,
+				}
 			case stateComment, stateNil:
 				// pass
 			case stateValue:
@@ -443,12 +486,16 @@ func ParseFile(r io.Reader) (*Modelfile, error) {
 					continue
 				}
 
-				if role != "" {
-					s = role + ": " + s
-					role = ""
+				switch cmd.Name {
+				case "parameter":
+					p := cmd.Args.(*Parameter)
+					p.Value = s
+				case "message":
+					m := cmd.Args.(*Message)
+					m.Content = s
+				default:
+					cmd.Args = s
 				}
-
-				cmd.Args = s
 				f.Commands = append(f.Commands, cmd)
 			}
 
@@ -473,11 +520,16 @@ func ParseFile(r io.Reader) (*Modelfile, error) {
 			return nil, io.ErrUnexpectedEOF
 		}
 
-		if role != "" {
-			s = role + ": " + s
+		switch cmd.Name {
+		case "parameter":
+			c := cmd.Args.(*Parameter)
+			c.Value = s
+		case "message":
+			c := cmd.Args.(*Message)
+			c.Content = s
+		default:
+			cmd.Args = s
 		}
-
-		cmd.Args = s
 		f.Commands = append(f.Commands, cmd)
 	default:
 		return nil, io.ErrUnexpectedEOF