1 files changed, 105 insertions, 3 deletions
diff --git a/compiler/evals.nim b/compiler/evals.nim
index 1d443a404..d2559176e 100755
--- a/compiler/evals.nim
+++ b/compiler/evals.nim
@@ -65,6 +65,7 @@ proc popStackFrame*(c: PEvalContext) {.inline.} =
   if (c.tos == nil): InternalError("popStackFrame")
   c.tos = c.tos.next
 
+proc eval*(c: PEvalContext, n: PNode): PNode
 proc evalAux(c: PEvalContext, n: PNode, flags: TEvalFlags): PNode
 
 proc stackTraceAux(x: PStackFrame) =
@@ -764,7 +765,7 @@ proc isEmpty(n: PNode): bool =
 proc stringStartingLine(s: PNode): int =
   result = s.info.line - countLines(s.strVal)
 
-proc evalParseExpr(c: PEvalContext, n: Pnode): Pnode =
+proc evalParseExpr(c: PEvalContext, n: PNode): PNode =
   var code = evalAux(c, n.sons[1], {})
   var ast = parseString(code.getStrValue, code.info.toFilename,
                         code.stringStartingLine)
@@ -773,12 +774,108 @@ proc evalParseExpr(c: PEvalContext, n: Pnode): Pnode =
   result = ast.sons[0]
   result.typ = newType(tyExpr, c.module)
 
-proc evalParseStmt(c: PEvalContext, n: Pnode): Pnode =
+proc evalParseStmt(c: PEvalContext, n: PNode): PNode =
   var code = evalAux(c, n.sons[1], {})
   result = parseString(code.getStrValue, code.info.toFilename,
                        code.stringStartingLine)
   result.typ = newType(tyStmt, c.module)
 
+proc evalTemplateAux*(templ, actual: PNode, sym: PSym): PNode = 
+  case templ.kind
+  of nkSym: 
+    var p = templ.sym
+    if (p.kind == skParam) and (p.owner.id == sym.id): 
+      result = copyTree(actual.sons[p.position])
+    else: 
+      result = copyNode(templ)
+  of nkNone..nkIdent, nkType..nkNilLit: # atom
+    result = copyNode(templ)
+  else: 
+    result = copyNode(templ)
+    newSons(result, sonsLen(templ))
+    for i in countup(0, sonsLen(templ) - 1): 
+      result.sons[i] = evalTemplateAux(templ.sons[i], actual, sym)
+
+proc evalTemplateArgs(n: PNode, s: PSym): PNode =
+  var 
+    f, a: int
+    arg: PNode
+    
+  f = sonsLen(s.typ)
+
+  # if the template has zero arguments, it can be called without ``()``
+  # `n` is then a nkSym or something similar
+  case n.kind
+  of nkCall, nkInfix, nkPrefix, nkPostfix, nkCommand, nkCallStrLit:
+    a = sonsLen(n)
+  else: a = 0
+  
+  if a > f: GlobalError(n.info, errWrongNumberOfArguments)
+
+  result = copyNode(n)
+  for i in countup(1, f - 1):
+    if i < a:
+      arg = n.sons[i]
+    else:
+      arg = copyTree(s.typ.n.sons[i].sym.ast)
+
+    addSon(result, arg)
+
+var evalTemplateCounter = 0
+  # to prevend endless recursion in templates instantation
+
+proc evalTemplate(n: PNode, sym: PSym): PNode = 
+  inc(evalTemplateCounter)
+  if evalTemplateCounter > 100:
+    GlobalError(n.info, errTemplateInstantiationTooNested)
+
+  # replace each param by the corresponding node:
+  var args = evalTemplateArgs(n, sym)
+  result = evalTemplateAux(sym.ast.sons[codePos], args, sym)
+
+  dec(evalTemplateCounter)
+
+proc evalMacroCall*(c: PEvalContext, n: PNode, sym: PSym): PNode =
+  inc(evalTemplateCounter)
+  if evalTemplateCounter > 100: 
+    GlobalError(n.info, errTemplateInstantiationTooNested)
+
+  var s = newStackFrame()
+  s.call = n
+  setlen(s.params, 2)
+  s.params[0] = newNodeIT(nkNilLit, n.info, sym.typ.sons[0])
+  s.params[1] = n
+  pushStackFrame(c, s)
+  discard eval(c, sym.ast.sons[codePos])
+  result = s.params[0]
+  popStackFrame(c)
+  if cyclicTree(result): GlobalError(n.info, errCyclicTree)
+
+  dec(evalTemplateCounter)
+  
+proc evalExpandToAst(c: PEvalContext, original: PNode): PNode =
+  var
+    n = original.copyTree
+    macroCall = n.sons[1]
+    expandedSym = macroCall.sons[0].sym
+
+  for i in countup(1, macroCall.sonsLen - 1):
+    macroCall.sons[i] = evalAux(c, macroCall.sons[i], {})
+
+  case expandedSym.kind
+  of skTemplate:
+    result = evalTemplate(macroCall, expandedSym)
+  of skMacro:
+    # At this point macroCall.sons[0] is nkSym node.
+    # To be completely compatible with normal macro invocation,
+    # we want to replace it with nkIdent node featuring
+    # the original unmangled macro name.
+    macroCall.sons[0] = newIdentNode(expandedSym.name, expandedSym.info)
+    result = evalMacroCall(c, macroCall, expandedSym)
+  else:
+    InternalError(macroCall.info,
+      "ExpandToAst: expanded symbol is no macro or template")
+
 proc evalMagicOrCall(c: PEvalContext, n: PNode): PNode = 
   var m = getMagic(n)
   case m
@@ -805,7 +902,8 @@ proc evalMagicOrCall(c: PEvalContext, n: PNode): PNode =
   of mAppendSeqElem: result = evalAppendSeqElem(c, n)
   of mParseExprToAst: result = evalParseExpr(c, n)
   of mParseStmtToAst: result = evalParseStmt(c, n)
-  of mNLen: 
+  of mExpandToAst: result = evalExpandToAst(c, n)
+  of mNLen:
     result = evalAux(c, n.sons[1], {efLValue})
     if isSpecial(result): return 
     var a = result
@@ -1011,6 +1109,10 @@ proc evalMagicOrCall(c: PEvalContext, n: PNode): PNode =
     if (a == b) or
         (b.kind in {nkNilLit, nkEmpty}) and (a.kind in {nkNilLit, nkEmpty}): 
       result.intVal = 1
+  of mNLineInfo:
+    result = evalAux(c, n.sons[1], {})
+    if isSpecial(result): return
+    result = newStrNodeT(result.info.toFileLineCol, n)
   of mAstToYaml:
     var ast = evalAux(c, n.sons[1], {efLValue})
     result = newStrNode(nkStrLit, ast.treeToYaml.ropeToStr)