Merge pull request #224 from gluon-lang/try_from_string

feat: Add a TryFrom<&str> implementation for enumerations

src/completion.rs

@@ -587,4 +587,14 @@ mod tests {
             "TypeParameter"
         );
     }
+
+    #[test]
+    fn test_try_from_enum() {
+        use std::convert::TryInto;
+        assert_eq!("Text".try_into(), Ok(CompletionItemKind::TEXT));
+        assert_eq!(
+            "TypeParameter".try_into(),
+            Ok(CompletionItemKind::TYPE_PARAMETER)
+        );
+    }
 }

src/lib.rs

@@ -15,20 +15,43 @@ able to parse any URI, such as `urn:isbn:0451450523`.
 
 */
 #![allow(non_upper_case_globals)]
-#![forbid(unsafe_code)]
-
+#[forbid(unsafe_code)]
 #[macro_use]
 extern crate bitflags;
 
-use serde::{Deserialize, Serialize};
-use std::fmt::Debug;
+use std::{collections::HashMap, fmt::Debug};
+
+use serde::{de, de::Error as Error_, Deserialize, Serialize};
+use serde_json::Value;
 pub use url::Url;
 
-use std::collections::HashMap;
+// Large enough to contain any enumeration name defined in this crate
+type PascalCaseBuf = [u8; 32];
+const fn fmt_pascal_case_const(name: &str) -> (PascalCaseBuf, usize) {
+    let mut buf = [0; 32];
+    let mut buf_i = 0;
+    let mut name_i = 0;
+    let name = name.as_bytes();
+    while name_i < name.len() {
+        let first = name[name_i];
+        name_i += 1;
+
+        buf[buf_i] = first;
+        buf_i += 1;
+
+        while name_i < name.len() {
+            let rest = name[name_i];
+            name_i += 1;
+            if rest == b'_' {
+                break;
+            }
 
-use serde::de;
-use serde::de::Error as Error_;
-use serde_json::Value;
+            buf[buf_i] = rest.to_ascii_lowercase();
+            buf_i += 1;
+        }
+    }
+    (buf, buf_i)
+}
 
 fn fmt_pascal_case(f: &mut std::fmt::Formatter<'_>, name: &str) -> std::fmt::Result {
     for word in name.split('_') {
@@ -43,7 +66,7 @@ fn fmt_pascal_case(f: &mut std::fmt::Formatter<'_>, name: &str) -> std::fmt::Res
 }
 
 macro_rules! lsp_enum {
-    (impl $typ: ty { $( $(#[$attr:meta])* pub const $name: ident : $enum_type: ty = $value: expr; )* }) => {
+    (impl $typ: ident { $( $(#[$attr:meta])* pub const $name: ident : $enum_type: ty = $value: expr; )* }) => {
         impl $typ {
             $(
             $(#[$attr])*
@@ -61,6 +84,23 @@ macro_rules! lsp_enum {
                 }
             }
         }
+
+        impl std::convert::TryFrom<&str> for $typ {
+            type Error = &'static str;
+            fn try_from(value: &str) -> Result<Self, Self::Error> {
+                match () {
+                    $(
+                        _ if {
+                            const X: (crate::PascalCaseBuf, usize) = crate::fmt_pascal_case_const(stringify!($name));
+                            let (buf, len) = X;
+                            &buf[..len] == value.as_bytes()
+                        } => Ok(Self::$name),
+                    )*
+                    _ => Err("unknown enum variant"),
+                }
+            }
+        }
+
     }
 }
 
@@ -668,10 +708,10 @@ pub struct ConfigurationItem {
 }
 
 mod url_map {
-    use super::*;
-
     use std::fmt;
 
+    use super::*;
+
     pub fn deserialize<'de, D>(
         deserializer: D,
     ) -> Result<Option<HashMap<Url, Vec<TextEdit>>>, D::Error>
@@ -2415,9 +2455,10 @@ impl SymbolTag {
 
 #[cfg(test)]
 mod tests {
-    use super::*;
     use serde::{Deserialize, Serialize};
 
+    use super::*;
+
     pub(crate) fn test_serialization<SER>(ms: &SER, expected: &str)
     where
         SER: Serialize + for<'de> Deserialize<'de> + PartialEq + std::fmt::Debug,