Make replace a template

Also required me to fix a name conflict with the format template

src/nre.nim

@@ -423,25 +423,32 @@ proc split*(str: string, pattern: Regex, maxSplit = -1): seq[string] =
     # This handles "2"
     result.add(str.substr(bounds.b, str.len - 1))
 
-proc replace*(str: string, pattern: Regex,
-              subproc: proc (match: RegexMatch): string): string =
+template replaceImpl(str: string, pattern: Regex,
+                     replacement: expr): stmt {.immediate, dirty.} =
   # XXX seems very similar to split, maybe I can reduce code duplication
   # somehow?
   result = ""
   var lastIdx = 0
-  for match in str.findIter(pattern):
+  for match {.inject.} in str.findIter(pattern):
     let bounds = match.matchBounds
     result.add(str.substr(lastIdx, bounds.a - 1))
-    result.add(subproc(match))
+    let nextVal = replacement
+    assert(nextVal != nil)
+    result.add(nextVal)
 
     lastIdx = bounds.b
 
   result.add(str.substr(lastIdx, str.len - 1))
+  return result
+
+proc replace*(str: string, pattern: Regex,
+              subproc: proc (match: RegexMatch): string): string =
+  replaceImpl(str, pattern, subproc(match))
 
 proc replace*(str: string, pattern: Regex, sub: string): string =
-  return str.replace(pattern, proc (match: RegexMatch): string =
-    # - 1 because the string numbers are 0-indexed
-    formatStr(sub, match.captures[name], match.captures[id - 1]) )
+  # - 1 because the string numbers are 0-indexed
+  replaceImpl(str, pattern,
+    formatStr(sub, match.captures[name], match.captures[id - 1]))
 
 # }}}
 

src/private/util.nim

@@ -11,20 +11,20 @@ const StartIdent = Ident - {'0'..'9'}
 
 template formatStr*(howExpr, namegetter, idgetter: expr): expr =
   let how = howExpr
-  result = newStringOfCap(how.len)
+  var val = newStringOfCap(how.len)
   var i = 0
   var lastNum = 1
 
   while i < how.len:
     if how[i] != '$':
-      result.add(how[i])
+      val.add(how[i])
       i += 1
     elif how[i + 1] == '$':
-      result.add('$')
+      val.add('$')
       i += 2
     elif how[i + 1] == '#':
       var id {.inject.} = lastNum
-      result.add(idgetter)
+      val.add(idgetter)
       lastNum += 1
       i += 2
     elif how[i + 1] in {'0'..'9'}:
@@ -33,7 +33,7 @@ template formatStr*(howExpr, namegetter, idgetter: expr): expr =
       while i < how.len and how[i] in {'0'..'9'}:
         id += (id * 10) + (ord(how[i]) - ord('0'))
         i += 1
-      result.add(idgetter)
+      val.add(idgetter)
       lastNum = id + 1
     elif how[i + 1] in StartIdent:
       i += 1
@@ -41,7 +41,7 @@ template formatStr*(howExpr, namegetter, idgetter: expr): expr =
       while i < how.len and how[i] in Ident:
         name.add(how[i])
         i += 1
-      result.add(namegetter)
+      val.add(namegetter)
     elif how[i + 1] == '{':
       i += 2
       var name {.inject.} = ""
@@ -49,6 +49,7 @@ template formatStr*(howExpr, namegetter, idgetter: expr): expr =
         name.add(how[i])
         i += 1
       i += 1
-      result.add(namegetter)
+      val.add(namegetter)
     else:
       raise newException(Exception, "Syntax error in format string at " & $i)
+  val