first commit

internal/imap/parser.go

@@ -0,0 +1,77 @@
+package imap
+
+import "strings"
+
+// tokenize splits an IMAP command line into space-separated tokens, treating
+// "quoted strings" and (parenthesized lists) as single tokens (lists keep
+// their outer parens so command handlers can recognize and further split
+// them). Literal syntax ({n}\r\n<bytes>) is not handled here — see session.go's
+// readCommand, which handles literals as a pre-pass before tokenizing since
+// they require reading raw bytes off the connection, not just string scanning.
+func tokenize(line string) []string {
+	var tokens []string
+	i, n := 0, len(line)
+
+	for i < n {
+		for i < n && (line[i] == ' ' || line[i] == '\t') {
+			i++
+		}
+		if i >= n {
+			break
+		}
+
+		switch line[i] {
+		case '"':
+			j := i + 1
+			var sb strings.Builder
+			for j < n && line[j] != '"' {
+				if line[j] == '\\' && j+1 < n {
+					j++
+				}
+				sb.WriteByte(line[j])
+				j++
+			}
+			tokens = append(tokens, sb.String())
+			i = j + 1
+
+		case '(':
+			depth := 1
+			j := i + 1
+			for j < n && depth > 0 {
+				switch line[j] {
+				case '(':
+					depth++
+				case ')':
+					depth--
+				}
+				j++
+			}
+			tokens = append(tokens, line[i:j])
+			i = j
+
+		default:
+			j := i
+			for j < n && line[j] != ' ' && line[j] != '\t' {
+				j++
+			}
+			tokens = append(tokens, line[i:j])
+			i = j
+		}
+	}
+	return tokens
+}
+
+// splitList takes a token like "(FLAGS UID)" and returns its inner
+// space-separated items — used by FETCH/STORE argument parsing.
+func splitList(token string) []string {
+	inner := strings.TrimPrefix(token, "(")
+	inner = strings.TrimSuffix(inner, ")")
+	if inner == "" {
+		return nil
+	}
+	return tokenize(inner)
+}
+
+func isList(token string) bool {
+	return strings.HasPrefix(token, "(") && strings.HasSuffix(token, ")")
+}