newStringOfCap implemented and used to optimize some procs

compiler/ast.nim

@@ -337,7 +337,9 @@ type
     mFields, mFieldPairs,
     mAppendStrCh, mAppendStrStr, mAppendSeqElem, 
     mInRange, mInSet, mRepr, mExit, mSetLengthStr, mSetLengthSeq, mAssert, 
-    mSwap, mIsNil, mArrToSeq, mCopyStr, mCopyStrLast, mNewString, mReset, 
+    mSwap, mIsNil, mArrToSeq, mCopyStr, mCopyStrLast, 
+    mNewString, mNewStringOfCap,
+    mReset,
     mArray, mOpenArray, mRange, mSet, mSeq, 
     mOrdinal, mInt, mInt8, mInt16, mInt32, 
     mInt64, mFloat, mFloat32, mFloat64, mBool, mChar, mString, mCstring, 

compiler/ccgexprs.nim

@@ -1457,7 +1457,8 @@ proc genMagicExpr(p: BProc, e: PNode, d: var TLoc, op: TMagic) =
   of mIncl, mExcl, mCard, mLtSet, mLeSet, mEqSet, mMulSet, mPlusSet, mMinusSet,
      mInSet:
     genSetOp(p, e, d, op)
-  of mNewString, mCopyStr, mCopyStrLast, mExit: genCall(p, e, d)
+  of mNewString, mNewStringOfCap, mCopyStr, mCopyStrLast, mExit: 
+    genCall(p, e, d)
   of mReset: genReset(p, e)
   of mEcho: genEcho(p, e)
   of mArrToSeq: genArrToSeq(p, e, d)

compiler/evals.nim

@@ -990,7 +990,13 @@ proc evalMagicOrCall(c: PEvalContext, n: PNode): PNode =
     var a = result
     result = newNodeIT(nkStrLit, n.info, n.typ)
     result.strVal = newString(int(getOrdValue(a)))
-  else: 
+  of mNewStringOfCap:
+    result = evalAux(c, n.sons[1], {})
+    if isSpecial(result): return 
+    var a = result
+    result = newNodeIT(nkStrLit, n.info, n.typ)
+    result.strVal = newString(0)
+  else:
     result = evalAux(c, n.sons[1], {})
     if isSpecial(result): return 
     var a = result

compiler/semfold.nim

@@ -1,7 +1,7 @@
 #
 #
 #           The Nimrod Compiler
-#        (c) Copyright 2010 Andreas Rumpf
+#        (c) Copyright 2011 Andreas Rumpf
 #
 #    See the file "copying.txt", included in this
 #    distribution, for details about the copyright.
@@ -205,7 +205,8 @@ proc evalOp(m: TMagic, n, a, b, c: PNode): PNode =
   of mCompileOptionArg:
     result = newIntNodeT(Ord(
       testCompileOptionArg(getStr(a), getStr(b), n.info)), n)
-  of mNewString, mExit, mInc, ast.mDec, mEcho, mAssert, mSwap, mAppendStrCh, 
+  of mNewString, mNewStringOfCap, 
+     mExit, mInc, ast.mDec, mEcho, mAssert, mSwap, mAppendStrCh, 
      mAppendStrStr, mAppendSeqElem, mSetLengthStr, mSetLengthSeq, 
      mNLen..mNError, mEqRef: 
     nil