Auto-fix: Add support for 'use_if_expressions'

Author: HugoGGuerrier

lkql_checker/share/lkql/use_if_expressions.lkql

@@ -1,9 +1,45 @@
+import stdlib
+
 fun simple_return(l) = l != null and l.children_count == 1 and l[1] is ReturnStmt
 fun simple_assignment(l) =
     l != null and l.children_count == 1 and l[1] is AssignStmt(f_dest: Name)
 
+fun replace_by_expr(if_stmt, ctx) =
+    |" Replace ``if_stmt`` node by a semantically equivalent node which use an
+    |" IfExpr to perform the conditional branching.
+    {
+        val is_return = simple_return(if_stmt.f_then_stmts);
+        val then_stmt = if_stmt.f_then_stmts[1];
+        val else_stmt = if_stmt.f_else_part.f_stmts[1];
+        val if_expr = new ParenExpr(new IfExpr(
+            f_cond_expr = if_stmt.f_cond_expr,
+            f_then_expr = if is_return then then_stmt.f_return_expr else then_stmt.f_expr,
+            f_else_expr = if is_return then else_stmt.f_return_expr else else_stmt.f_expr,
+            f_alternatives=new ElsifExprPartList([
+                {
+                    val stmt = part.f_stmts[1];
+                    new ElsifExprPart(
+                        f_cond_expr = part.f_cond_expr,
+                        f_then_expr = if is_return then stmt.f_return_expr else stmt.f_expr
+                    )
+                }
+                for part in if_stmt.f_alternatives.children
+            ].to_list)
+        ));
+        ctx.replace(
+            if_stmt,
+            if is_return
+            then new ReturnStmt(if_expr)
+            else new AssignStmt(
+                f_dest = then_stmt.f_dest,
+                f_expr = if_expr
+            )
+        )
+    }
+
 @check(message="IF statement may be replaced by an IF expression",
-       category="Style", subcategory="Programming Practice")
+       category="Style", subcategory="Programming Practice",
+       auto_fix=replace_by_expr)
 fun use_if_expressions(node) =
     |" Flag ``if`` statements which could be replaced by an ``if`` expression.
     |" This rule detects the following code patterns:
@@ -53,12 +89,14 @@ fun use_if_expressions(node) =
     node is IfStmt
     when (simple_return(node.f_then_stmts) and
           simple_return(node.f_else_part?.f_stmts) and
-          not [s for s in node.f_alternatives.children
-               if not simple_return(s.f_stmts)])
+          stdlib.all([simple_return(s.f_stmts)
+                      for s in node.f_alternatives.children]))
       or (simple_assignment(node.f_then_stmts) and
           simple_assignment(node.f_else_part?.f_stmts) and
-          not [s for s in node.f_alternatives.children
-               if not simple_assignment(s.f_stmts)] and {
-          val stmts = from node select AssignStmt;
-          val lhs = stmts[1].f_dest;
-          not [s for s in stmts if not s.f_dest.p_name_matches(lhs)]})
+          stdlib.all([simple_assignment(s.f_stmts)
+                      for s in node.f_alternatives.children]) and
+          {
+              val stmts = from node select AssignStmt;
+              val lhs = stmts[1].f_dest;
+              stdlib.all([s.f_dest.p_name_matches(lhs) for s in stmts])
+          })

testsuite/tests/checks/use_if_expressions/stmt.adb

@@ -47,7 +47,7 @@ begin
 
    if X > 0 then    --  NOFLAG
       return 2;
-   end if:
+   end if;
 
    return X;
 end Stmt;

testsuite/tests/checks/use_if_expressions/test.out

@@ -25,3 +25,38 @@ stmt.adb:40:4: rule violation: IF statement may be replaced by an IF expression
 46 ||    end if;
    ||__________^
 
+Patched "stmt.adb":
+===================
+
+function Stmt (X : in out Integer) return Integer is
+   Y : Integer;
+begin
+   return(if X = 1 then 1 else 2);if X = 1 then   --  NOFLAG
+      null;
+   else
+      null;
+   end if;
+
+   return(if X = 1 then 1 elsif X = 2 then 2 else 3);if X = 1 then   --  NOFLAG
+      return 1;
+   elsif X = 2 then
+      X := 2;
+   else
+      return 3;
+   end if;
+
+   if X >= 2 then   --  NOFLAG
+      X := X + 1;
+   elsif X <= 0 then
+      Y := X - 1;
+   else
+      X := 0;
+   end if;
+
+   X :=(if X >= 2 then X + 1 elsif X <= 0 then X - 1 else 0);if X > 0 then    --  NOFLAG
+      return 2;
+   end if;
+
+   return X;
+end Stmt;
+

testsuite/tests/checks/use_if_expressions/test.yaml

@@ -1,3 +1,4 @@
 driver: 'checker'
 rule_name: Use_If_Expressions
 input_sources: ['stmt.adb']
+auto_fix: True