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

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)