nimpretty: add #!nimpretty on/off directives

compiler/layouter.nim

@@ -31,7 +31,7 @@ type
     inquote: bool
     semicolons: SemicolonKind
     col, lastLineNumber, lineSpan, indentLevel, indWidth: int
-    inParamList*: int
+    keepIndents*: int
     doIndentMore*: int
     content: string
     indentStack: seq[int]
@@ -134,6 +134,22 @@ proc emitTok*(em: var Emitter; L: TLexer; tok: TToken) =
         for i in 1 .. LineCommentColumn - em.col: wr(" ")
     wr lit
 
+  if tok.tokType == tkComment and tok.literal.startsWith("#!nimpretty"):
+    case tok.literal
+    of "#!nimpretty off":
+      inc em.keepIndents
+      wr("\L")
+      em.lastLineNumber = tok.line + 1
+    of "#!nimpretty on":
+      dec em.keepIndents
+      em.lastLineNumber = tok.line
+    wr("\L")
+    #for i in 1 .. tok.indent: wr " "
+    wr tok.literal
+    em.col = 0
+    em.lineSpan = 0
+    return
+
   var preventComment = false
   if tok.tokType == tkComment and tok.line == em.lastLineNumber and tok.indent >= 0:
     # we have an inline comment so handle it before the indentation token:
@@ -142,7 +158,7 @@ proc emitTok*(em: var Emitter; L: TLexer; tok: TToken) =
     em.fixedUntil = em.content.high
 
   elif tok.indent >= 0:
-    if em.lastTok in (splitters + oprSet) or em.inParamList > 0:
+    if em.lastTok in (splitters + oprSet) or em.keepIndents > 0:
       em.indentLevel = tok.indent
     else:
       if tok.indent > em.indentStack[^1]: