parsecfg: handle streams and strings when saving or loading configuration (#5554)

lib/pure/parsecfg.nim

@@ -430,16 +430,15 @@ proc newConfig*(): Config =
   ## Useful when wanting to create a configuration file.
   result = newOrderedTable[string, OrderedTableRef[string, string]]()
 
-proc loadConfig*(filename: string): Config =
-  ## Load the specified configuration file into a new Config instance.
+proc loadConfig*(stream: Stream, filename: string = "[stream]"): Config =
+  ## Load the specified configuration from stream into a new Config instance.
+  ## `filename` parameter is only used for nicer error messages.
   var dict = newOrderedTable[string, OrderedTableRef[string, string]]()
   var curSection = "" ## Current section,
                       ## the default value of the current section is "",
                       ## which means that the current section is a common
   var p: CfgParser
-  var fileStream = newFileStream(filename, fmRead)
-  if fileStream != nil:
-    open(p, fileStream, filename)
+  open(p, stream, filename)
   while true:
     var e = next(p)
     case e.kind
@@ -464,6 +463,13 @@ proc loadConfig*(filename: string): Config =
   close(p)
   result = dict
 
+proc loadConfig*(filename: string): Config =
+  ## Load the specified configuration file into a new Config instance.
+  let file = open(filename, fmRead)
+  let fileStream = newFileStream(file)
+  defer: fileStream.close()
+  result = fileStream.loadConfig(filename)
+
 proc replace(s: string): string =
   var d = ""
   var i = 0
@@ -482,24 +488,19 @@ proc replace(s: string): string =
     inc(i)
   result = d
 
-proc writeConfig*(dict: Config, filename: string) =
-  ## Writes the contents of the table to the specified configuration file.
-  ## Note: Comment statement will be ignored.
-  var file: File
-  if file.open(filename, fmWrite):
-    try:
-      var section, key, value, kv, segmentChar:string
-      for pair in dict.pairs():
-        section = pair[0]
+proc writeConfig*(dict: Config, stream: Stream) =
+  ## Writes the contents of the table to the specified stream
+  ##
+  ## **Note:** Comment statement will be ignored.
+  for section, sectionData in dict.pairs():
     if section != "": ## Not general section
       if not allCharsInSet(section, SymChars): ## Non system character
-            file.writeLine("[\"" & section & "\"]")
+        stream.writeLine("[\"" & section & "\"]")
       else:
-            file.writeLine("[" & section & "]")
-        for pair2 in pair[1].pairs():
-          key = pair2[0]
-          value = pair2[1]
-          if key[0] == '-' and key[1] == '-': ## If it is a command key
+        stream.writeLine("[" & section & "]")
+    for key, value in sectionData.pairs():
+      var kv, segmentChar: string
+      if key.len > 1 and key[0] == '-' and key[1] == '-': ## If it is a command key
         segmentChar = ":"
         if not allCharsInSet(key[2..key.len()-1], SymChars):
           kv.add("--\"")
@@ -525,11 +526,23 @@ proc writeConfig*(dict: Config, filename: string) =
         else:
           kv.add(segmentChar)
           kv.add(value)
-          file.writeLine(kv)
-    except:
-      raise
-    finally:
-      file.close()
+      stream.writeLine(kv)
+
+proc `$`*(dict: Config): string =
+  ## Writes the contents of the table to string.
+  ## Note: Comment statement will be ignored.
+  let stream = newStringStream()
+  defer: stream.close()
+  dict.writeConfig(stream)
+  result = stream.data
+
+proc writeConfig*(dict: Config, filename: string) =
+  ## Writes the contents of the table to the specified configuration file.
+  ## Note: Comment statement will be ignored.
+  let file = open(filename, fmWrite)
+  let fileStream = newFileStream(filename)
+  defer: fileStream.close()
+  dict.writeConfig(fileStream)
 
 proc getSectionValue*(dict: Config, section, key: string): string =
   ## Gets the Key value of the specified Section.

tests/stdlib/tparscfg.nim

@@ -1,4 +1,31 @@
-import parsecfg
+discard """
+output: '''
+utf-8
+on
+hello
+lihf8515
+10214028
+lihaifeng@wxm.com
+===
+charset=utf-8
+[Package]
+name=hello
+--threads:on
+[Author]
+name=lhf
+qq=10214028
+email="lihaifeng@wxm.com"
+===
+charset=utf-8
+[Package]
+name=hello
+--threads:on
+[Author]
+name=lihf8515
+qq=10214028
+'''
+"""
+import parsecfg, streams
 
 ## Creating a configuration file.
 var dict1=newConfig()
@@ -8,10 +35,11 @@ dict1.setSectionKey("Package","--threads","on")
 dict1.setSectionKey("Author","name","lihf8515")
 dict1.setSectionKey("Author","qq","10214028")
 dict1.setSectionKey("Author","email","lihaifeng@wxm.com")
-dict1.writeConfig("config.ini")
+var ss = newStringStream()
+dict1.writeConfig(ss)
 
 ## Reading a configuration file.
-var dict2 = loadConfig("config.ini")
+var dict2 = loadConfig(newStringStream(ss.data))
 var charset = dict2.getSectionValue("","charset")
 var threads = dict2.getSectionValue("Package","--threads")
 var pname = dict2.getSectionValue("Package","name")
@@ -25,13 +53,17 @@ echo name
 echo qq
 echo email
 
+echo "==="
+
 ## Modifying a configuration file.
-var dict3 = loadConfig("config.ini")
+var dict3 = loadConfig(newStringStream(ss.data))
 dict3.setSectionKey("Author","name","lhf")
-dict3.writeConfig("config.ini")
+write(stdout, $dict3)
+
+echo "==="
 
 ## Deleting a section key in a configuration file.
-var dict4 = loadConfig("config.ini")
+var dict4 = loadConfig(newStringStream(ss.data))
 dict4.delSectionKey("Author","email")
-dict4.writeConfig("config.ini")
+write(stdout, $dict4)