feat: add 4 transformations

- dfmt_space_before_function_parameters
- dfmt_space_after_cast
- dfmt_align_switch_statements
- dfmt_space_before_aa_colon

Signed-off-by: Prajwal S N <prajwalnadig21@gmail.com>

README.md

@@ -113,7 +113,7 @@ dfmt_align_switch_statements | **`true`**, `false` | Align labels, cases, and de
 dfmt_outdent_attributes (Not yet implemented) | **`true`**, `false`| Decrease the indentation level of attributes.
 dfmt_split_operator_at_line_end | `true`, **`false`** | Place operators on the end of the previous line when splitting lines.
 dfmt_space_after_cast | **`true`**, `false` | Insert space after the closing paren of a `cast` expression.
-dfmt_space_after_keywords (Not yet implemented) | **`true`**, `false` | Insert space after `if`, `while`, `foreach`, etc, and before the `(`.
+dfmt_space_after_keywords | **`true`**, `false` | Insert space after `if`, `while`, `foreach`, etc, and before the `(`.
 dfmt_space_before_function_parameters | `true`, **`false`** | Insert space before the opening paren of a function parameter list.
 dfmt_selective_import_space | **`true`**, `false` | Insert space after the module name and before the `:` for selective imports.
 dfmt_compact_labeled_statements | **`true`**, `false` | Place labels on the same line as the labeled `switch`, `for`, `foreach`, or `while` statement.
@@ -124,7 +124,6 @@ dfmt_space_before_named_arg_colon | `true`, **`false`** | Adds a space after a n
 dfmt_keep_line_breaks | `true`, **`false`** | Keep existing line breaks if these don't violate other formatting rules.
 dfmt_single_indent | `true`, **`false`** | Set if the code in parens is indented by a single tab instead of two.
 dfmt_reflow_property_chains | **`true`**, `false` | Recalculate the splitting of property chains into multiple lines.
-dfmt_space_after_keywords | **`true`**, `false` | Insert space after keywords (if,while,foreach,for, etc.).
 
 ## Terminology
 * Braces - `{` and `}`

src/dfmt/ast.d

@@ -385,6 +385,8 @@ extern (C++) class FormatVisitor : SemanticTimeTransitiveVisitor
                 if (i)
                     write(", ");
                 writeExprWithPrecedence(key, PREC.assign);
+                if (config.dfmt_space_before_aa_colon == OptionalBoolean.t)
+                    write(' ');
                 write(": ");
                 auto value = (*e.values)[i];
                 writeExprWithPrecedence(value, PREC.assign);
@@ -792,6 +794,10 @@ extern (C++) class FormatVisitor : SemanticTimeTransitiveVisitor
                 write(MODtoString(e.mod));
             }
             write(')');
+            if (config.dfmt_space_after_cast)
+            {
+                write(' ');
+            }
             writeExprWithPrecedence(e.e1, precedence[e.op]);
         }
 
@@ -1589,6 +1595,8 @@ extern (C++) class FormatVisitor : SemanticTimeTransitiveVisitor
 
         void visitCase(ASTCodegen.CaseStatement s)
         {
+            if (config.dfmt_align_switch_statements)
+                depth--;
             write("case ");
             writeExpr(s.exp);
             write(':');
@@ -1596,6 +1604,8 @@ extern (C++) class FormatVisitor : SemanticTimeTransitiveVisitor
             insideCase = true;
             writeStatement(s.statement);
             insideCase = false;
+            if (config.dfmt_align_switch_statements)
+                depth++;
         }
 
         void visitCaseRange(ASTCodegen.CaseRangeStatement s)
@@ -1611,9 +1621,13 @@ extern (C++) class FormatVisitor : SemanticTimeTransitiveVisitor
 
         void visitDefault(ASTCodegen.DefaultStatement s)
         {
+            if (config.dfmt_align_switch_statements)
+                depth--;
             write("default:");
             newline();
             writeStatement(s.statement);
+            if (config.dfmt_align_switch_statements)
+                depth++;
         }
 
         void visitGotoDefault(ASTCodegen.GotoDefaultStatement _)
@@ -1978,7 +1992,9 @@ extern (C++) class FormatVisitor : SemanticTimeTransitiveVisitor
                 if (ex)
                 {
                     writeExpr(ex);
-                    write(':');
+                    if (config.dfmt_space_before_aa_colon == OptionalBoolean.t)
+                        write(' ');
+                    write(": ");
                 }
                 if (auto iz = ai.value[i])
                     writeInitializer(iz);
@@ -2602,6 +2618,8 @@ extern (C++) class FormatVisitor : SemanticTimeTransitiveVisitor
 
     void writeParamList(ParameterList pl)
     {
+        if (config.dfmt_space_before_function_parameters)
+            write(' ');
         write('(');
         foreach (i; 0 .. pl.length)
         {