fix: follow clippy checks

Signed-off-by: fan <yfan3763@gmail.com>

src/error.rs

@@ -4,21 +4,21 @@ pub type Result<T> = core::result::Result<T, Error>;
 
 #[derive(Clone, Debug, PartialEq)]
 pub enum Error {
-    ParseErr(String),
-    StorageErr(String),
-    InternalErr(String),
-    ConfErr(String),
-    OtherErr(String),
+    Parse(String),
+    Storage(String),
+    Internal(String),
+    Conf(String),
+    Other(String),
 }
 
 impl Display for Error {
     fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
         match self {
-            Self::ParseErr(err)
-            | Self::StorageErr(err)
-            | Self::InternalErr(err)
-            | Self::ConfErr(err)
-            | Self::OtherErr(err) => {
+            Self::Parse(err)
+            | Self::Storage(err)
+            | Self::Internal(err)
+            | Self::Conf(err)
+            | Self::Other(err) => {
                 write!(f, "{}", err)
             }
         }

src/parser/keyword.rs

@@ -203,7 +203,7 @@ impl fmt::Display for Keyword {
     }
 }
 
-pub fn find_keyword(keyword_str: &String) -> Keyword {
+pub fn find_keyword(keyword_str: &str) -> Keyword {
     // 转化为大写
     let upper_keyword_str = keyword_str.to_uppercase();
 

src/parser/lexer.rs

@@ -180,12 +180,12 @@ impl Lexer {
 
 // 是否是 字母开头
 fn is_letter(ch: char) -> bool {
-    (ch >= 'a' && ch <= 'z') || (ch >= 'A' && ch <= 'Z') || ch == '_'
+    ch.is_ascii_alphabetic() || ch == '_'
 }
 
 // 是否是 数字
 fn is_digit(ch: char) -> bool {
-    ch >= '0' && ch <= '9'
+    ch.is_numeric()
 }
 
 #[cfg(test)]