2 files changed, 112 insertions, 29 deletions

diff --git a/crates/hir_ty/src/diagnostics/decl_check.rs b/crates/hir_ty/src/diagnostics/decl_check.rs
index 083df3772..1a0906492 100644
--- a/crates/hir_ty/src/diagnostics/decl_check.rs
+++ b/crates/hir_ty/src/diagnostics/decl_check.rs
@@ -9,6 +9,8 @@
 // If you see these lines in the pull request, feel free to call me stupid :P.
 #![allow(dead_code, unused_imports, unused_variables)]
 
+mod str_helpers;
+
 use std::sync::Arc;
 
 use hir_def::{
@@ -18,7 +20,7 @@ use hir_def::{
     item_tree::ItemTreeNode,
     resolver::{resolver_for_expr, ResolveValueResult, ValueNs},
     src::HasSource,
-    AdtId, FunctionId, Lookup, ModuleDefId,
+    AdtId, EnumId, FunctionId, Lookup, ModuleDefId, StructId,
 };
 use hir_expand::{diagnostics::DiagnosticSink, name::Name};
 use syntax::{
@@ -28,7 +30,7 @@ use syntax::{
 
 use crate::{
     db::HirDatabase,
-    diagnostics::{CaseType, IncorrectCase},
+    diagnostics::{decl_check::str_helpers::*, CaseType, IncorrectCase},
     lower::CallableDefId,
     ApplicationTy, InferenceResult, Ty, TypeCtor,
 };
@@ -191,41 +193,30 @@ impl<'a, 'b> DeclValidator<'a, 'b> {
         }
     }
 
-    fn validate_adt(&mut self, db: &dyn HirDatabase, adt: AdtId) {}
-}
-
-fn pat_equals_to_name(pat: Option<ast::Pat>, name: &Name) -> bool {
-    if let Some(ast::Pat::IdentPat(ident)) = pat {
-        ident.to_string() == name.to_string()
-    } else {
-        false
+    fn validate_adt(&mut self, db: &dyn HirDatabase, adt: AdtId) {
+        match adt {
+            AdtId::StructId(struct_id) => self.validate_struct(db, struct_id),
+            AdtId::EnumId(enum_id) => self.validate_enum(db, enum_id),
+            AdtId::UnionId(_) => {
+                // Unions aren't yet supported by this validator.
+            }
+        }
     }
-}
 
-fn to_lower_snake_case(ident: &str) -> Option<String> {
-    // First, assume that it's UPPER_SNAKE_CASE.
-    if let Some(normalized) = to_lower_snake_case_from_upper_snake_case(ident) {
-        return Some(normalized);
+    fn validate_struct(&mut self, db: &dyn HirDatabase, struct_id: StructId) {
+        let data = db.struct_data(struct_id);
     }
 
-    // Otherwise, assume that it's CamelCase.
-    let lower_snake_case = stdx::to_lower_snake_case(ident);
-
-    if lower_snake_case == ident {
-        None
-    } else {
-        Some(lower_snake_case)
+    fn validate_enum(&mut self, db: &dyn HirDatabase, enum_id: EnumId) {
+        let data = db.enum_data(enum_id);
     }
 }
 
-fn to_lower_snake_case_from_upper_snake_case(ident: &str) -> Option<String> {
-    let is_upper_snake_case = ident.chars().all(|c| c.is_ascii_uppercase() || c == '_');
-
-    if is_upper_snake_case {
-        let string = ident.chars().map(|c| c.to_ascii_lowercase()).collect();
-        Some(string)
+fn pat_equals_to_name(pat: Option<ast::Pat>, name: &Name) -> bool {
+    if let Some(ast::Pat::IdentPat(ident)) = pat {
+        ident.to_string() == name.to_string()
     } else {
-        None
+        false
     }
 }
 
diff --git a/crates/hir_ty/src/diagnostics/decl_check/str_helpers.rs b/crates/hir_ty/src/diagnostics/decl_check/str_helpers.rs
new file mode 100644
index 000000000..3d8f1b5f2
--- /dev/null
+++ b/crates/hir_ty/src/diagnostics/decl_check/str_helpers.rs
@@ -0,0 +1,92 @@
+pub fn to_camel_case(ident: &str) -> Option<String> {
+    let mut output = String::new();
+
+    if is_camel_case(ident) {
+        return None;
+    }
+
+    let mut capital_added = false;
+    for chr in ident.chars() {
+        if chr.is_alphabetic() {
+            if !capital_added {
+                output.push(chr.to_ascii_uppercase());
+                capital_added = true;
+            } else {
+                output.push(chr.to_ascii_lowercase());
+            }
+        } else if chr == '_' {
+            // Skip this character and make the next one capital.
+            capital_added = false;
+        } else {
+            // Put the characted as-is.
+            output.push(chr);
+        }
+    }
+
+    if output == ident {
+        None
+    } else {
+        Some(output)
+    }
+}
+
+pub fn to_lower_snake_case(ident: &str) -> Option<String> {
+    // First, assume that it's UPPER_SNAKE_CASE.
+    if let Some(normalized) = to_lower_snake_case_from_upper_snake_case(ident) {
+        return Some(normalized);
+    }
+
+    // Otherwise, assume that it's CamelCase.
+    let lower_snake_case = stdx::to_lower_snake_case(ident);
+
+    if lower_snake_case == ident {
+        None
+    } else {
+        Some(lower_snake_case)
+    }
+}
+
+fn to_lower_snake_case_from_upper_snake_case(ident: &str) -> Option<String> {
+    if is_upper_snake_case(ident) {
+        let string = ident.chars().map(|c| c.to_ascii_lowercase()).collect();
+        Some(string)
+    } else {
+        None
+    }
+}
+
+fn is_upper_snake_case(ident: &str) -> bool {
+    ident.chars().all(|c| c.is_ascii_uppercase() || c == '_')
+}
+
+fn is_camel_case(ident: &str) -> bool {
+    // We assume that the string is either snake case or camel case.
+    ident.chars().all(|c| c != '_')
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    use expect_test::{expect, Expect};
+
+    fn check<F: Fn(&str) -> Option<String>>(fun: F, input: &str, expect: Expect) {
+        // `None` is translated to empty string, meaning that there is nothing to fix.
+        let output = fun(input).unwrap_or_default();
+
+        expect.assert_eq(&output);
+    }
+
+    #[test]
+    fn test_to_lower_snake_case() {
+        check(to_lower_snake_case, "lower_snake_case", expect![[""]]);
+        check(to_lower_snake_case, "UPPER_SNAKE_CASE", expect![["upper_snake_case"]]);
+        check(to_lower_snake_case, "CamelCase", expect![["camel_case"]]);
+    }
+
+    #[test]
+    fn test_to_camel_case() {
+        check(to_camel_case, "CamelCase", expect![[""]]);
+        check(to_camel_case, "lower_snake_case", expect![["LowerSnakeCase"]]);
+        check(to_camel_case, "UPPER_SNAKE_CASE", expect![["UpperSnakeCase"]]);
+    }
+}