feat: Write built in themes to the themes file on first run so users can define custom themes

proc_macros/validate_theme_derive/src/lib.rs

@@ -1,18 +1,18 @@
 use proc_macro::TokenStream;
 use quote::quote;
-use syn::{parse_macro_input, Data, DeriveInput, Fields};
+use syn::{Data, DeriveInput, Fields, parse_macro_input};
 
 /// Derive macro for generating a `validate` method for a Theme struct.
 /// The `validate` method ensures that all values with the `validate` attribute are not `None`.
 /// Otherwise, an error message it output to both the log file and stdout and the program exits.
-/// 
+///
 /// # Example
-/// 
+///
 /// Valid themes pass through the program transitively without any messages being output.
-/// 
+///
 /// ```
 /// use validate_theme_derive::ValidateTheme;
-/// 
+///
 /// #[derive(ValidateTheme, Default)]
 /// struct Theme {
 ///     pub name: String,
@@ -22,22 +22,22 @@ use syn::{parse_macro_input, Data, DeriveInput, Fields};
 ///     pub bad: Option<Style>,
 ///     pub ugly: Option<Style>,
 /// }
-/// 
+///
 /// struct Style {
 /// 	color: String,
 /// }
-/// 
+///
 /// let theme = Theme {
 /// 	good: Some(Style { color: "Green".to_owned() }),
 /// 	bad: Some(Style { color: "Red".to_owned() }),
 /// 	..Theme::default()
 /// };
-/// 
+///
 /// // Since only `good` and `bad` have the `validate` attribute, the `validate` method will only check those fields.
 /// theme.validate();
 /// // Since both `good` and `bad` have values, the program will not exit and no message is output.
 /// ```
-/// 
+///
 /// Invalid themes will output an error message to both the log file and stdout and the program will exit.
 ///
 /// ```should_panic
@@ -61,44 +61,46 @@ use syn::{parse_macro_input, Data, DeriveInput, Fields};
 ///     bad: Some(Style { color: "Red".to_owned() }),
 ///     ..Theme::default()
 /// };
-/// 
+///
 /// // Since `good` has the `validate` attribute and since `good` is `None`, the `validate` method will output an error message and exit the program.
 /// theme.validate();
 /// ```
 #[proc_macro_derive(ValidateTheme, attributes(validate))]
 pub fn derive_validate_theme(input: TokenStream) -> TokenStream {
-	let input = parse_macro_input!(input as DeriveInput);
-	let struct_name = &input.ident;
+  let input = parse_macro_input!(input as DeriveInput);
+  let struct_name = &input.ident;
 
-	let mut validation_checks = Vec::new();
+  let mut validation_checks = Vec::new();
 
-	if let Data::Struct(data_struct) = &input.data {
-		if let Fields::Named(fields) = &data_struct.fields {
-			for field in &fields.named {
-				let field_name = &field.ident;
+  if let Data::Struct(data_struct) = &input.data {
+    if let Fields::Named(fields) = &data_struct.fields {
+      for field in &fields.named {
+        let field_name = &field.ident;
 
-				let has_validate_attr = field.attrs.iter().any(|attr| {
-					attr.path().is_ident("validate")
-				});
+        let has_validate_attr = field
+          .attrs
+          .iter()
+          .any(|attr| attr.path().is_ident("validate"));
 
-				if has_validate_attr {
-					validation_checks.push(quote! {
-						if self.#field_name.is_none() {
-							log::error!("{} is missing a color value.", stringify!(#field_name));
-							eprintln!("{} is missing a color value.", stringify!(#field_name));
-							std::process::exit(1);
-						}
-					})
-				}
-			}
-		}
-	}
+        if has_validate_attr {
+          validation_checks.push(quote! {
+            if self.#field_name.is_none() {
+              log::error!("{} is missing a color value.", stringify!(#field_name));
+              eprintln!("{} is missing a color value.", stringify!(#field_name));
+              std::process::exit(1);
+            }
+          })
+        }
+      }
+    }
+  }
 
-	quote! {
-		impl #struct_name {
-			pub fn validate(&self) {
-				#(#validation_checks)*
-			}
-		}
-	}.into()
+  quote! {
+    impl #struct_name {
+      pub fn validate(&self) {
+        #(#validation_checks)*
+      }
+    }
+  }
+  .into()
 }