added the 'x.p[:T]' notation for explicit generic instantiations in combination with the ddot calling syntax

changelog.md

@@ -27,6 +27,9 @@
 
 ### Language additions
 
+- Dot calls combined with explicit generic instantiations can now be written
+  as ``x.y[:z]``. ``x.y[:z]`` that is transformed into ``y[z](x)`` in the parser.
+
 ### Language changes
 
 - The `importcpp` pragma now allows importing the listed fields of generic

compiler/docgen.nim

@@ -257,7 +257,8 @@ proc nodeToHighlightedHtml(d: PDoc; n: PNode; result: var Rope; renderFlags: TRe
        tkBracketDotLe, tkBracketDotRi, tkParDotLe,
        tkParDotRi, tkComma, tkSemiColon, tkColon, tkEquals, tkDot, tkDotDot,
        tkAccent, tkColonColon,
-       tkGStrLit, tkGTripleStrLit, tkInfixOpr, tkPrefixOpr, tkPostfixOpr:
+       tkGStrLit, tkGTripleStrLit, tkInfixOpr, tkPrefixOpr, tkPostfixOpr,
+       tkBracketLeColon:
       dispA(result, "<span class=\"Other\">$1</span>", "\\spanOther{$1}",
             [rope(esc(d.target, literal))])
 

compiler/lexer.nim

@@ -60,7 +60,7 @@ type
     tkCurlyDotLe, tkCurlyDotRi, # {.  and  .}
     tkParDotLe, tkParDotRi,   # (. and .)
     tkComma, tkSemiColon,
-    tkColon, tkColonColon, tkEquals, tkDot, tkDotDot,
+    tkColon, tkColonColon, tkEquals, tkDot, tkDotDot, tkBracketLeColon,
     tkOpr, tkComment, tkAccent,
     tkSpaces, tkInfixOpr, tkPrefixOpr, tkPostfixOpr
 
@@ -98,7 +98,7 @@ const
     "tkTripleStrLit", "tkGStrLit", "tkGTripleStrLit", "tkCharLit", "(",
     ")", "[", "]", "{", "}", "[.", ".]", "{.", ".}", "(.", ".)",
     ",", ";",
-    ":", "::", "=", ".", "..",
+    ":", "::", "=", ".", "..", "[:",
     "tkOpr", "tkComment", "`",
     "tkSpaces", "tkInfixOpr",
     "tkPrefixOpr", "tkPostfixOpr"]
@@ -1119,6 +1119,9 @@ proc rawGetTok*(L: var TLexer, tok: var TToken) =
       if L.buf[L.bufpos] == '.' and L.buf[L.bufpos+1] != '.':
         tok.tokType = tkBracketDotLe
         inc(L.bufpos)
+      elif L.buf[L.bufpos] == ':':
+        tok.tokType = tkBracketLeColon
+        inc(L.bufpos)
       else:
         tok.tokType = tkBracketLe
     of ']':

compiler/parser.nim

@@ -389,20 +389,6 @@ proc exprList(p: var TParser, endTok: TTokType, result: PNode) =
     getTok(p)
     optInd(p, a)
 
-proc dotExpr(p: var TParser, a: PNode): PNode =
-  #| dotExpr = expr '.' optInd symbol
-  var info = p.parLineInfo
-  getTok(p)
-  result = newNodeI(nkDotExpr, info)
-  optInd(p, result)
-  addSon(result, a)
-  addSon(result, parseSymbol(p, smAfterDot))
-
-proc qualifiedIdent(p: var TParser): PNode =
-  #| qualifiedIdent = symbol ('.' optInd symbol)?
-  result = parseSymbol(p)
-  if p.tok.tokType == tkDot: result = dotExpr(p, result)
-
 proc exprColonEqExprListAux(p: var TParser, endTok: TTokType, result: PNode) =
   assert(endTok in {tkCurlyRi, tkCurlyDotRi, tkBracketRi, tkParRi})
   getTok(p)
@@ -423,6 +409,33 @@ proc exprColonEqExprList(p: var TParser, kind: TNodeKind,
   result = newNodeP(kind, p)
   exprColonEqExprListAux(p, endTok, result)
 
+proc dotExpr(p: var TParser, a: PNode): PNode =
+  #| dotExpr = expr '.' optInd (symbol | '[:' exprList ']')
+  #| explicitGenericInstantiation = '[:' exprList ']' ( '(' exprColonEqExpr ')' )?
+  var info = p.parLineInfo
+  getTok(p)
+  result = newNodeI(nkDotExpr, info)
+  optInd(p, result)
+  addSon(result, a)
+  addSon(result, parseSymbol(p, smAfterDot))
+  if p.tok.tokType == tkBracketLeColon and p.tok.strongSpaceA <= 0:
+    var x = newNodeI(nkBracketExpr, p.parLineInfo)
+    # rewrite 'x.y[:z]()' to 'y[z](x)'
+    x.add result[1]
+    exprList(p, tkBracketRi, x)
+    eat(p, tkBracketRi)
+    var y = newNodeI(nkCall, p.parLineInfo)
+    y.add x
+    y.add result[0]
+    if p.tok.tokType == tkParLe and p.tok.strongSpaceA <= 0:
+      exprColonEqExprListAux(p, tkParRi, y)
+    result = y
+
+proc qualifiedIdent(p: var TParser): PNode =
+  #| qualifiedIdent = symbol ('.' optInd symbol)?
+  result = parseSymbol(p)
+  if p.tok.tokType == tkDot: result = dotExpr(p, result)
+
 proc setOrTableConstr(p: var TParser): PNode =
   #| setOrTableConstr = '{' ((exprColonEqExpr comma)* | ':' ) '}'
   result = newNodeP(nkCurly, p)

doc/grammar.txt

@@ -26,9 +26,10 @@ symbol = '`' (KEYW|IDENT|literal|(operator|'('|')'|'['|']'|'{'|'}'|'=')+)+ '`'
        | IDENT | KEYW
 exprColonEqExpr = expr (':'|'=' expr)?
 exprList = expr ^+ comma
-dotExpr = expr '.' optInd symbol
-qualifiedIdent = symbol ('.' optInd symbol)?
 exprColonEqExprList = exprColonEqExpr (comma exprColonEqExpr)* (comma)?
+dotExpr = expr '.' optInd (symbol | '[:' exprList ']')
+explicitGenericInstantiation = '[:' exprList ']' ( '(' exprColonEqExpr ')' )?
+qualifiedIdent = symbol ('.' optInd symbol)?
 setOrTableConstr = '{' ((exprColonEqExpr comma)* | ':' ) '}'
 castExpr = 'cast' '[' optInd typeDesc optPar ']' '(' optInd expr optPar ')'
 parKeyw = 'discard' | 'include' | 'if' | 'while' | 'case' | 'try'

doc/manual/generics.txt

@@ -550,7 +550,7 @@ object inheritance syntax involving the ``of`` keyword:
   proc f(g: BidirectionalGraph) # this one will be preferred if we pass a type
                                 # matching the BidirectionalGraph concept
 
-
+..
   Converter type classes
   ----------------------
 

doc/manual/lexing.txt

@@ -411,7 +411,7 @@ Other tokens
 
 The following strings denote other tokens::
 
-    `   (     )     {     }     [     ]     ,  ;   [.    .]  {.   .}  (.  .)
+    `   (    )     {    }     [    ]    ,  ;   [.    .]  {.   .}  (.  .)  [:
 
 
 The `slice`:idx: operator `..`:tok: takes precedence over other tokens that

doc/manual/procs.txt

@@ -141,13 +141,14 @@ The method call syntax conflicts with explicit generic instantiations:
 ``p[T](x)`` cannot be written as ``x.p[T]`` because ``x.p[T]`` is always
 parsed as ``(x.p)[T]``.
 
-**Future directions**: ``p[.T.]`` might be introduced as an alternative syntax
-to pass explicit types to a generic and then ``x.p[.T.]`` can be parsed as
-``x.(p[.T.])``.
-
 See also: `Limitations of the method call syntax
 <#templates-limitations-of-the-method-call-syntax>`_.
 
+The ``[: ]`` notation has been designed to mitigate this issue: ``x.p[:T]``
+is rewritten by the parser to ``p[T](x)``, ``x.p[:T](y)`` is rewritten to
+``p[T](x, y)``. Note that ``[: ]`` has no AST representation, the rewrite
+is performed directly in the parsing step.
+
 
 Properties
 ----------

tests/parser/tprecedence.nim

@@ -1,6 +1,7 @@
 discard """
   output: '''holla
-true'''
+true
+defabc 4'''
 """
 
 # Test top level semicolon works properly:
@@ -13,3 +14,8 @@ proc `\*` (x, y: int): int = result = x * y
 
 echo 5 \+ 1 \* 9 == 6*9
 
+proc foo[S, T](x: S, y: T): T = x & y
+
+proc bar[T](x: T): T = x
+
+echo "def".foo[:string, string]("abc"), " ", 4.bar[:int]