Implemented error messages

src/build/Scan.go

@@ -8,6 +8,7 @@ import (
 
 	"git.akyoto.dev/cli/q/src/build/directory"
 	"git.akyoto.dev/cli/q/src/build/token"
+	"git.akyoto.dev/cli/q/src/errors"
 )
 
 // Scan scans the directory.
@@ -86,46 +87,141 @@ func scanFile(path string, functions chan<- *Function) error {
 	tokens := token.Tokenize(contents)
 
 	var (
+		i           = 0
 		groupLevel  = 0
 		blockLevel  = 0
-		headerStart = -1
+		nameStart   = -1
+		paramsStart = -1
 		bodyStart   = -1
 	)
 
-	for i, t := range tokens {
-		switch t.Kind {
-		case token.Identifier:
-			if blockLevel == 0 && groupLevel == 0 {
-				headerStart = i
+	for {
+		// Function name
+		for i < len(tokens) {
+			if tokens[i].Kind == token.Identifier {
+				nameStart = i
+				i++
+				break
 			}
 
-		case token.GroupStart:
-			groupLevel++
-
-		case token.GroupEnd:
-			groupLevel--
-
-		case token.BlockStart:
-			blockLevel++
-
-			if blockLevel == 1 {
-				bodyStart = i
+			if tokens[i].Kind == token.NewLine {
+				i++
+				continue
 			}
 
-		case token.BlockEnd:
-			blockLevel--
+			if tokens[i].Kind == token.EOF {
+				return nil
+			}
 
-			if blockLevel == 0 {
-				function := &Function{
-					Name: tokens[headerStart].Text(),
-					Head: tokens[headerStart:bodyStart],
-					Body: tokens[bodyStart : i+1],
+			return errors.New(errors.ExpectedFunctionName, path, tokens, i)
+		}
+
+		// Function parameters
+		for i < len(tokens) {
+			if tokens[i].Kind == token.GroupStart {
+				groupLevel++
+
+				if groupLevel == 1 {
+					paramsStart = i
 				}
 
-				functions <- function
+				i++
+				continue
 			}
-		}
-	}
 
-	return nil
+			if tokens[i].Kind == token.GroupEnd {
+				groupLevel--
+
+				if groupLevel < 0 {
+					return errors.New(errors.MissingGroupStart, path, tokens, i)
+				}
+
+				i++
+
+				if groupLevel == 0 {
+					break
+				}
+
+				continue
+			}
+
+			if tokens[i].Kind == token.EOF {
+				if groupLevel > 0 {
+					return errors.New(errors.MissingGroupEnd, path, tokens, i)
+				}
+
+				if paramsStart == -1 {
+					return errors.New(errors.ExpectedFunctionParameters, path, tokens, i)
+				}
+
+				return nil
+			}
+
+			if groupLevel > 0 {
+				i++
+				continue
+			}
+
+			return errors.New(errors.ExpectedFunctionParameters, path, tokens, i)
+		}
+
+		// Function definition
+		for i < len(tokens) {
+			if tokens[i].Kind == token.BlockStart {
+				blockLevel++
+
+				if blockLevel == 1 {
+					bodyStart = i
+				}
+
+				i++
+				continue
+			}
+
+			if tokens[i].Kind == token.BlockEnd {
+				blockLevel--
+
+				if blockLevel < 0 {
+					return errors.New(errors.MissingBlockStart, path, tokens, i)
+				}
+
+				i++
+
+				if blockLevel == 0 {
+					break
+				}
+
+				continue
+			}
+
+			if tokens[i].Kind == token.EOF {
+				if blockLevel > 0 {
+					return errors.New(errors.MissingBlockEnd, path, tokens, i)
+				}
+
+				if bodyStart == -1 {
+					return errors.New(errors.ExpectedFunctionDefinition, path, tokens, i)
+				}
+
+				return nil
+			}
+
+			if blockLevel > 0 {
+				i++
+				continue
+			}
+
+			return errors.New(errors.ExpectedFunctionDefinition, path, tokens, i)
+		}
+
+		functions <- &Function{
+			Name: tokens[nameStart].Text(),
+			Head: tokens[paramsStart:bodyStart],
+			Body: tokens[bodyStart : i+1],
+		}
+
+		nameStart = -1
+		paramsStart = -1
+		bodyStart = -1
+	}
 }