Add Kernighan & Ritchie style brace formatting.

The original K&R style behaves like BraceStyle.otbs, except for function definitions that use Allman style.

src/dfmt/ast_info.d

@@ -95,6 +95,12 @@ struct ASTInformation
     /// Closing braces of function literals
     size_t[] funLitEndLocations;
 
+    /// Locations of aggregate bodies (struct, class, union)
+    size_t[] aggregateBodyLocations;
+
+    /// Locations of function bodies
+    size_t[] funBodyLocations;
+
     /// Conditional statements that have matching "else" statements
     size_t[] conditionalWithElseLocations;
 
@@ -200,6 +206,15 @@ final class FormatVisitor : ASTVisitor
         destructor.accept(this);
     }
 
+    override void visit (const FunctionBody functionBody)
+    {
+        if (auto bd = functionBody.specifiedFunctionBody)
+        {
+            astInformation.funBodyLocations ~= bd.blockStatement.startLocation;
+        }
+        functionBody.accept(this);
+    }
+
     override void visit(const ConditionalDeclaration dec)
     {
         if (dec.hasElse)
@@ -313,6 +328,7 @@ final class FormatVisitor : ASTVisitor
 
     override void visit(const StructBody structBody)
     {
+        astInformation.aggregateBodyLocations ~= structBody.startLocation;
         astInformation.doubleNewlineLocations ~= structBody.endLocation;
         structBody.accept(this);
     }

src/dfmt/config.d

@@ -16,7 +16,9 @@ enum BraceStyle
     /// $(LINK https://en.wikipedia.org/wiki/Indent_style#Variant:_1TBS)
     otbs,
     /// $(LINK https://en.wikipedia.org/wiki/Indent_style#Variant:_Stroustrup)
-    stroustrup
+    stroustrup,
+    /// $(LINK https://en.wikipedia.org/wiki/Indentation_style#K&R_style)
+    knr,
 }
 
 enum TemplateConstraintStyle

src/dfmt/formatter.d

@@ -15,6 +15,7 @@ import dfmt.indentation;
 import dfmt.tokens;
 import dfmt.wrapping;
 import std.array;
+import std.algorithm.comparison : among;
 
 /**
  * Formats the code contained in `buffer` into `output`.
@@ -963,6 +964,10 @@ private:
                 if (config.dfmt_brace_style == BraceStyle.allman
                         || peekBackIsOneOf(true, tok!"{", tok!"}"))
                     newline();
+                else if (config.dfmt_brace_style == BraceStyle.knr
+                        && astInformation.funBodyLocations.canFindIndex(tIndex)
+                        && (peekBackIs(tok!")") || (!peekBackIs(tok!"do") && peekBack().text != "body")))
+                    newline();
                 else if (!peekBackIsOneOf(true, tok!"{", tok!"}", tok!";"))
                     write(" ");
                 writeToken();
@@ -1031,7 +1036,7 @@ private:
                 currentLineLength = 0;
                 justAddedExtraNewline = true;
             }
-            if (config.dfmt_brace_style == BraceStyle.otbs
+            if (config.dfmt_brace_style.among(BraceStyle.otbs, BraceStyle.knr)
                     && ((peekIs(tok!"else")
                             && !indents.topAre(tok!"static", tok!"if")
                             && !indents.topIs(tok!"foreach") && !indents.topIs(tok!"for")