extracted the fields iterator magic to its own file

2 files changed, 160 insertions, 147 deletions

diff --git a/compiler/semfields.nim b/compiler/semfields.nim
new file mode 100644
index 000000000..70dead8ab
--- /dev/null
+++ b/compiler/semfields.nim
@@ -0,0 +1,159 @@
+#
+#
+#           The Nim Compiler
+#        (c) Copyright 2014 Andreas Rumpf
+#
+#    See the file "copying.txt", included in this
+#    distribution, for details about the copyright.
+#
+
+## This module does the semantic transformation of the fields* iterators.
+#  included from semstmts.nim
+
+type
+  TFieldInstCtx = object  # either 'tup[i]' or 'field' is valid
+    tupleType: PType      # if != nil we're traversing a tuple
+    tupleIndex: int
+    field: PSym
+    replaceByFieldName: bool
+
+proc instFieldLoopBody(c: TFieldInstCtx, n: PNode, forLoop: PNode): PNode =
+  case n.kind
+  of nkEmpty..pred(nkIdent), succ(nkIdent)..nkNilLit: result = n
+  of nkIdent:
+    result = n
+    var L = sonsLen(forLoop)
+    if c.replaceByFieldName:
+      if n.ident.id == forLoop[0].ident.id:
+        let fieldName = if c.tupleType.isNil: c.field.name.s
+                        elif c.tupleType.n.isNil: "Field" & $c.tupleIndex
+                        else: c.tupleType.n.sons[c.tupleIndex].sym.name.s
+        result = newStrNode(nkStrLit, fieldName)
+        return
+    # other fields:
+    for i in ord(c.replaceByFieldName)..L-3:
+      if n.ident.id == forLoop[i].ident.id:
+        var call = forLoop.sons[L-2]
+        var tupl = call.sons[i+1-ord(c.replaceByFieldName)]
+        if c.field.isNil:
+          result = newNodeI(nkBracketExpr, n.info)
+          result.add(tupl)
+          result.add(newIntNode(nkIntLit, c.tupleIndex))
+        else:
+          result = newNodeI(nkDotExpr, n.info)
+          result.add(tupl)
+          result.add(newSymNode(c.field, n.info))
+        break
+  else:
+    if n.kind == nkContinueStmt:
+      localError(n.info, errGenerated,
+                 "'continue' not supported in a 'fields' loop")
+    result = copyNode(n)
+    newSons(result, sonsLen(n))
+    for i in countup(0, sonsLen(n)-1):
+      result.sons[i] = instFieldLoopBody(c, n.sons[i], forLoop)
+
+type
+  TFieldsCtx = object
+    c: PContext
+    m: TMagic
+
+proc semForObjectFields(c: TFieldsCtx, typ, forLoop, father: PNode) =
+  case typ.kind
+  of nkSym:
+    var fc: TFieldInstCtx  # either 'tup[i]' or 'field' is valid
+    fc.field = typ.sym
+    fc.replaceByFieldName = c.m == mFieldPairs
+    openScope(c.c)
+    inc c.c.inUnrolledContext
+    let body = instFieldLoopBody(fc, lastSon(forLoop), forLoop)
+    father.add(semStmt(c.c, body))
+    dec c.c.inUnrolledContext
+    closeScope(c.c)
+  of nkNilLit: discard
+  of nkRecCase:
+    let L = forLoop.len
+    let call = forLoop.sons[L-2]
+    if call.len > 2:
+      localError(forLoop.info, errGenerated, 
+                 "parallel 'fields' iterator does not work for 'case' objects")
+      return
+    # iterate over the selector:
+    semForObjectFields(c, typ[0], forLoop, father)
+    # we need to generate a case statement:
+    var caseStmt = newNodeI(nkCaseStmt, forLoop.info)
+    # generate selector:
+    var access = newNodeI(nkDotExpr, forLoop.info, 2)
+    access.sons[0] = call.sons[1]
+    access.sons[1] = newSymNode(typ.sons[0].sym, forLoop.info)
+    caseStmt.add(semExprWithType(c.c, access))
+    # copy the branches over, but replace the fields with the for loop body:
+    for i in 1 .. <typ.len:
+      var branch = copyTree(typ[i])
+      let L = branch.len
+      branch.sons[L-1] = newNodeI(nkStmtList, forLoop.info)
+      semForObjectFields(c, typ[i].lastSon, forLoop, branch[L-1])
+      caseStmt.add(branch)
+    father.add(caseStmt)
+  of nkRecList:
+    for t in items(typ): semForObjectFields(c, t, forLoop, father)
+  else:
+    illFormedAst(typ)
+
+proc semForFields(c: PContext, n: PNode, m: TMagic): PNode =
+  # so that 'break' etc. work as expected, we produce
+  # a 'while true: stmt; break' loop ...
+  result = newNodeI(nkWhileStmt, n.info, 2)
+  var trueSymbol = strTableGet(magicsys.systemModule.tab, getIdent"true")
+  if trueSymbol == nil: 
+    localError(n.info, errSystemNeeds, "true")
+    trueSymbol = newSym(skUnknown, getIdent"true", getCurrOwner(), n.info)
+    trueSymbol.typ = getSysType(tyBool)
+
+  result.sons[0] = newSymNode(trueSymbol, n.info)
+  var stmts = newNodeI(nkStmtList, n.info)
+  result.sons[1] = stmts
+  
+  var length = sonsLen(n)
+  var call = n.sons[length-2]
+  if length-2 != sonsLen(call)-1 + ord(m==mFieldPairs):
+    localError(n.info, errWrongNumberOfVariables)
+    return result
+  
+  var tupleTypeA = skipTypes(call.sons[1].typ, abstractVar-{tyTypeDesc})
+  if tupleTypeA.kind notin {tyTuple, tyObject}:
+    localError(n.info, errGenerated, "no object or tuple type")
+    return result
+  for i in 1..call.len-1:
+    var tupleTypeB = skipTypes(call.sons[i].typ, abstractVar-{tyTypeDesc})
+    if not sameType(tupleTypeA, tupleTypeB):
+      typeMismatch(call.sons[i], tupleTypeA, tupleTypeB)
+  
+  inc(c.p.nestedLoopCounter)
+  if tupleTypeA.kind == tyTuple:
+    var loopBody = n.sons[length-1]
+    for i in 0..sonsLen(tupleTypeA)-1:
+      openScope(c)
+      var fc: TFieldInstCtx
+      fc.tupleType = tupleTypeA
+      fc.tupleIndex = i
+      fc.replaceByFieldName = m == mFieldPairs
+      var body = instFieldLoopBody(fc, loopBody, n)
+      inc c.inUnrolledContext
+      stmts.add(semStmt(c, body))
+      dec c.inUnrolledContext
+      closeScope(c)
+  else:
+    var fc: TFieldsCtx
+    fc.m = m
+    fc.c = c
+    semForObjectFields(fc, tupleTypeA.n, n, stmts)
+  dec(c.p.nestedLoopCounter)
+  # for TR macros this 'while true: ...; break' loop is pretty bad, so
+  # we avoid it now if we can:
+  if hasSonWith(stmts, nkBreakStmt):
+    var b = newNodeI(nkBreakStmt, n.info)
+    b.add(ast.emptyNode)
+    stmts.add(b)
+  else:
+    result = stmts
diff --git a/compiler/semstmts.nim b/compiler/semstmts.nim
index c67fdb0f9..ab1c47e68 100644
--- a/compiler/semstmts.nim
+++ b/compiler/semstmts.nim
@@ -465,153 +465,7 @@ proc semConst(c: PContext, n: PNode): PNode =
     addSon(b, copyTree(def))
     addSon(result, b)
 
-type
-  TFieldInstCtx = object  # either 'tup[i]' or 'field' is valid
-    tupleType: PType      # if != nil we're traversing a tuple
-    tupleIndex: int
-    field: PSym
-    replaceByFieldName: bool
-
-proc instFieldLoopBody(c: TFieldInstCtx, n: PNode, forLoop: PNode): PNode =
-  case n.kind
-  of nkEmpty..pred(nkIdent), succ(nkIdent)..nkNilLit: result = n
-  of nkIdent:
-    result = n
-    var L = sonsLen(forLoop)
-    if c.replaceByFieldName:
-      if n.ident.id == forLoop[0].ident.id:
-        let fieldName = if c.tupleType.isNil: c.field.name.s
-                        elif c.tupleType.n.isNil: "Field" & $c.tupleIndex
-                        else: c.tupleType.n.sons[c.tupleIndex].sym.name.s
-        result = newStrNode(nkStrLit, fieldName)
-        return
-    # other fields:
-    for i in ord(c.replaceByFieldName)..L-3:
-      if n.ident.id == forLoop[i].ident.id:
-        var call = forLoop.sons[L-2]
-        var tupl = call.sons[i+1-ord(c.replaceByFieldName)]
-        if c.field.isNil:
-          result = newNodeI(nkBracketExpr, n.info)
-          result.add(tupl)
-          result.add(newIntNode(nkIntLit, c.tupleIndex))
-        else:
-          result = newNodeI(nkDotExpr, n.info)
-          result.add(tupl)
-          result.add(newSymNode(c.field, n.info))
-        break
-  else:
-    if n.kind == nkContinueStmt:
-      localError(n.info, errGenerated,
-                 "'continue' not supported in a 'fields' loop")
-    result = copyNode(n)
-    newSons(result, sonsLen(n))
-    for i in countup(0, sonsLen(n)-1):
-      result.sons[i] = instFieldLoopBody(c, n.sons[i], forLoop)
-
-type
-  TFieldsCtx = object
-    c: PContext
-    m: TMagic
-
-proc semForObjectFields(c: TFieldsCtx, typ, forLoop, father: PNode) =
-  case typ.kind
-  of nkSym:
-    var fc: TFieldInstCtx  # either 'tup[i]' or 'field' is valid
-    fc.field = typ.sym
-    fc.replaceByFieldName = c.m == mFieldPairs
-    openScope(c.c)
-    inc c.c.inUnrolledContext
-    let body = instFieldLoopBody(fc, lastSon(forLoop), forLoop)
-    father.add(semStmt(c.c, body))
-    dec c.c.inUnrolledContext
-    closeScope(c.c)
-  of nkNilLit: discard
-  of nkRecCase:
-    let L = forLoop.len
-    let call = forLoop.sons[L-2]
-    if call.len > 2:
-      localError(forLoop.info, errGenerated, 
-                 "parallel 'fields' iterator does not work for 'case' objects")
-      return
-    # iterate over the selector:
-    semForObjectFields(c, typ[0], forLoop, father)
-    # we need to generate a case statement:
-    var caseStmt = newNodeI(nkCaseStmt, forLoop.info)
-    # generate selector:
-    var access = newNodeI(nkDotExpr, forLoop.info, 2)
-    access.sons[0] = call.sons[1]
-    access.sons[1] = newSymNode(typ.sons[0].sym, forLoop.info)
-    caseStmt.add(semExprWithType(c.c, access))
-    # copy the branches over, but replace the fields with the for loop body:
-    for i in 1 .. <typ.len:
-      var branch = copyTree(typ[i])
-      let L = branch.len
-      branch.sons[L-1] = newNodeI(nkStmtList, forLoop.info)
-      semForObjectFields(c, typ[i].lastSon, forLoop, branch[L-1])
-      caseStmt.add(branch)
-    father.add(caseStmt)
-  of nkRecList:
-    for t in items(typ): semForObjectFields(c, t, forLoop, father)
-  else:
-    illFormedAst(typ)
-
-proc semForFields(c: PContext, n: PNode, m: TMagic): PNode =
-  # so that 'break' etc. work as expected, we produce
-  # a 'while true: stmt; break' loop ...
-  result = newNodeI(nkWhileStmt, n.info, 2)
-  var trueSymbol = strTableGet(magicsys.systemModule.tab, getIdent"true")
-  if trueSymbol == nil: 
-    localError(n.info, errSystemNeeds, "true")
-    trueSymbol = newSym(skUnknown, getIdent"true", getCurrOwner(), n.info)
-    trueSymbol.typ = getSysType(tyBool)
-
-  result.sons[0] = newSymNode(trueSymbol, n.info)
-  var stmts = newNodeI(nkStmtList, n.info)
-  result.sons[1] = stmts
-  
-  var length = sonsLen(n)
-  var call = n.sons[length-2]
-  if length-2 != sonsLen(call)-1 + ord(m==mFieldPairs):
-    localError(n.info, errWrongNumberOfVariables)
-    return result
-  
-  var tupleTypeA = skipTypes(call.sons[1].typ, abstractVar-{tyTypeDesc})
-  if tupleTypeA.kind notin {tyTuple, tyObject}:
-    localError(n.info, errGenerated, "no object or tuple type")
-    return result
-  for i in 1..call.len-1:
-    var tupleTypeB = skipTypes(call.sons[i].typ, abstractVar-{tyTypeDesc})
-    if not sameType(tupleTypeA, tupleTypeB):
-      typeMismatch(call.sons[i], tupleTypeA, tupleTypeB)
-  
-  inc(c.p.nestedLoopCounter)
-  if tupleTypeA.kind == tyTuple:
-    var loopBody = n.sons[length-1]
-    for i in 0..sonsLen(tupleTypeA)-1:
-      openScope(c)
-      var fc: TFieldInstCtx
-      fc.tupleType = tupleTypeA
-      fc.tupleIndex = i
-      fc.replaceByFieldName = m == mFieldPairs
-      var body = instFieldLoopBody(fc, loopBody, n)
-      inc c.inUnrolledContext
-      stmts.add(semStmt(c, body))
-      dec c.inUnrolledContext
-      closeScope(c)
-  else:
-    var fc: TFieldsCtx
-    fc.m = m
-    fc.c = c
-    semForObjectFields(fc, tupleTypeA.n, n, stmts)
-  dec(c.p.nestedLoopCounter)
-  # for TR macros this 'while true: ...; break' loop is pretty bad, so
-  # we avoid it now if we can:
-  if hasSonWith(stmts, nkBreakStmt):
-    var b = newNodeI(nkBreakStmt, n.info)
-    b.add(ast.emptyNode)
-    stmts.add(b)
-  else:
-    result = stmts
+include semfields
 
 proc addForVarDecl(c: PContext, v: PSym) =
   if warnShadowIdent in gNotes: