implemented 'bind' for macros

compiler/evals.nim

@@ -40,6 +40,7 @@ type
     lastException*: PNode
     mode*: TEvalMode
     globals*: TIdNodeTable    # state of global vars
+    boundSyms: TStrTable      # for 'bind' support within macros
   
   PEvalContext* = ref TEvalContext
 
@@ -65,6 +66,7 @@ proc newEvalContext*(module: PSym, filename: string,
   result.module = module
   result.mode = mode
   initIdNodeTable(result.globals)
+  initStrTable(result.boundSyms)
 
 proc pushStackFrame*(c: PEvalContext, t: PStackFrame) {.inline.} = 
   t.next = c.tos
@@ -931,6 +933,26 @@ proc evalExpandToAst(c: PEvalContext, original: PNode): PNode =
       "ExpandToAst: expanded symbol is no macro or template")
     result = emptyNode
 
+proc getBoundSym(c: PEvalContext, n: PNode): PNode =
+  # we return either an nkSym or an nkSymChoice; XXX we really need
+  # to distinguish between open and closed nkSymChoice somehow.
+  var ident = getIdent(n.strVal)
+
+  # semantic checking requires a type; ``fitNode`` deals with it
+  # appropriately
+  result = newNodeIT(nkSymChoice, n.info, newType(tyNone, c.module))
+
+  var ii: TIdentIter
+  var a = InitIdentIter(ii, c.boundSyms, ident)
+  while a != nil:
+    incl(a.flags, sfUsed)
+    addSon(result, newSymNode(a, n.info))
+    a = NextIdentIter(ii, c.boundSyms)
+  case result.len
+  of 0: stackTrace(c, n, errUndeclaredIdentifier, n.strVal)
+  of 1: result = result.sons[0]
+  else: nil
+
 proc evalMagicOrCall(c: PEvalContext, n: PNode): PNode = 
   var m = getMagic(n)
   case m
@@ -1151,6 +1173,13 @@ proc evalMagicOrCall(c: PEvalContext, n: PNode): PNode =
     result = evalAux(c, n.sons[1], {efLValue})
     if isSpecial(result): return 
     result = copyTree(result)
+  of mNGetBoundSym:
+    result = evalAux(c, n.sons[1], {})
+    if isSpecial(result): return 
+    if not (result.kind in {nkStrLit..nkTripleStrLit}): 
+      stackTrace(c, n, errFieldXNotFound, "getBoundSym")
+      return
+    result = getBoundSym(c, result)
   of mStrToIdent: 
     result = evalAux(c, n.sons[1], {})
     if isSpecial(result): return 
@@ -1240,6 +1269,11 @@ proc evalMagicOrCall(c: PEvalContext, n: PNode): PNode =
     if isEmpty(a) or isEmpty(b) or isEmpty(cc): result = emptyNode
     else: result = evalOp(m, n, a, b, cc)
   
+proc evalBindStmt(c: PEvalContext, n: PNode) =
+  for i in 0 .. < n.len:
+    let a = n.sons[i]
+    if a.kind == nkSym: StrTableAdd(c.boundSyms, a.sym)
+  
 proc evalAux(c: PEvalContext, n: PNode, flags: TEvalFlags): PNode = 
   result = emptyNode
   dec(gNestedEvals)
@@ -1310,6 +1344,8 @@ proc evalAux(c: PEvalContext, n: PNode, flags: TEvalFlags): PNode =
     result.typ = n.typ
   of nkPragmaBlock:
     result = evalAux(c, n.sons[1], flags)
+  of nkBindStmt:
+    evalBindStmt(c, n)
   of nkIdentDefs, nkCast, nkYieldStmt, nkAsmStmt, nkForStmt, nkPragmaExpr, 
      nkLambdaKinds, nkContinueStmt, nkIdent, nkParForStmt: 
     result = raiseCannotEval(c, n.info)