Implement Steve Main template processing suggestion.

src/GamCommands.txt

@@ -44,6 +44,7 @@ If an item contains spaces, it should be surrounded by " or '.
 <Time> ::= <Year>-<Month>-<Day>(<Space>|T)<Hour>:<Minute>[:<Second>[.<MilliSeconds>[Z]]]
 <PrintJobAge> ::= <Number>(m|h|d)
 <REPattern> ::= <Python Regular Expression, see: https://docs.python.org/2/library/re.html>
+<Tag> ::= <String>
 <UniqueID> ::= uid:<String>
 
 # Named items
@@ -723,7 +724,7 @@ gam <UserTypeEntity> show sendas
 
 gam <UserTypeEntity> shortcuts <Boolean>
 
-gam <UserTypeEntity> signature|sig <String>|(file <FileName> [charset <Charset>]) (replace <REPattern> <String>)*
+gam <UserTypeEntity> signature|sig <String>|(file <FileName> [charset <Charset>]) (replace <Tag> <String>)*
 gam <UserTypeEntity> show signature|sig [format]
 
 gam <UserTypeEntity> snippets <Boolean>
@@ -731,7 +732,7 @@ gam <UserTypeEntity> snippets <Boolean>
 gam <UserTypeEntity> utf|utf8|utf-8|unicode <Boolean>
 
 gam <UserTypeEntity> vacation <FalseValues>
-gam <UserTypeEntity> vacation <TrueValues> subject <String> (message <String>)|(file <FileName> [charset <CharSet>]) (replace <REPattern> <String>)*
+gam <UserTypeEntity> vacation <TrueValues> subject <String> (message <String>)|(file <FileName> [charset <CharSet>]) (replace <Tag> <String>)*
 	[contactsonly] [domainonly] [startdate <Date>] [enddate <Date>]
 gam <UserTypeEntity> show vacation
 

src/gam.py

@@ -382,19 +382,6 @@ def getCharSet(i):
     return (i, GC_Values.get(GC_CHARSET, GM_Globals[GM_SYS_ENCODING]))
   return (i+2, sys.argv[i+1])
 
-def getREPattern(i):
-  if i < len(sys.argv):
-    patstr = sys.argv[i]
-    if patstr:
-      try:
-        pattern = re.compile(patstr)
-        return pattern
-      except re.error as e:
-        print u'ERROR: "{0}" is not a valid RE pattern: {1}'.format(patstr, e)
-        sys.exit(2)
-  print u'ERROR: expected an <REPattern>'
-  sys.exit(2)
-
 def getString(i, item, emptyOK=False, optional=False):
   if i < len(sys.argv):
     argstr = sys.argv[i]
@@ -5090,7 +5077,31 @@ def getForward(users):
     except TypeError:
       pass
 
+RT_PATTERN = re.compile(r'(?s){RT}.*?{(.*?)}.*?{/RT}')
+RT_OPEN_PATTERN = re.compile(r'{RT}')
+RT_CLOSE_PATTERN = re.compile(r'{/RT}')
+RT_STRIP_PATTERN = re.compile(r'(?s){RT}.*?{/RT}')
+RT_TAG_REPLACE_PATTERN = re.compile(r'{(.*?)}')
+
+def processTags(tagReplacements, message):
+  while True:
+    match = RT_PATTERN.search(message)
+    if not match:
+      break
+    if tagReplacements.get(match.group(1)):
+      message = RT_OPEN_PATTERN.sub(u'', message, count=1)
+      message = RT_CLOSE_PATTERN.sub(u'', message, count=1)
+    else:
+      message = RT_STRIP_PATTERN.sub(u'', message, count=1)
+  while True:
+    match = RT_TAG_REPLACE_PATTERN.search(message)
+    if not match:
+      break
+    message = re.sub(match.group(0), tagReplacements.get(match.group(1), u''), message)
+  return message
+
 def doSignature(users):
+  tagReplacements = {}
   i = 4
   if sys.argv[i].lower() == u'file':
     filename = sys.argv[i+1]
@@ -5102,13 +5113,15 @@ def doSignature(users):
     i += 1
   while i < len(sys.argv):
     if sys.argv[i].lower() == u'replace':
-      matchPattern = getREPattern(i+1)
+      matchTag = getString(i+1, u'Tag')
       matchReplacement = getString(i+2, u'String', emptyOK=True)
-      signature = matchPattern.sub(matchReplacement, signature)
+      tagReplacements[matchTag] = matchReplacement
       i += 3
     else:
       print u'ERROR: %s is not a valid argument for "gam <users> signature"' % sys.argv[i]
       sys.exit(2)
+  if tagReplacements:
+    signature = processTags(tagReplacements, signature)
   emailsettings = getEmailSettingsObject()
   count = len(users)
   i = 1
@@ -5172,6 +5185,7 @@ def doWebClips(users):
 
 def doVacation(users):
   subject = message = u''
+  tagReplacements = {}
   if sys.argv[4].lower() in true_values:
     enable = True
   elif sys.argv[4].lower() in false_values:
@@ -5207,9 +5221,9 @@ def doVacation(users):
       i, encoding = getCharSet(i)
       message = readFile(filename, encoding=encoding)
     elif sys.argv[i].lower() == u'replace':
-      matchPattern = getREPattern(i+1)
+      matchTag = getString(i+1, u'Tag')
       matchReplacement = getString(i+2, u'String', emptyOK=True)
-      message = matchPattern.sub(matchReplacement, message)
+      tagReplacements[matchTag] = matchReplacement
       i += 3
     else:
       print u'ERROR: %s is not a valid argument for "gam <users> vacation"' % sys.argv[i]
@@ -5218,6 +5232,8 @@ def doVacation(users):
   count = len(users)
   emailsettings = getEmailSettingsObject()
   message = message.replace(u'\\n', u'\n')
+  if tagReplacements:
+    message = processTags(tagReplacements, message)
   for user in users:
     if user.find(u'@') > 0:
       emailsettings.domain = user[user.find(u'@')+1:]

src/whatsnew.txt

@@ -8,10 +8,13 @@ Added argument to gam print cros to limit number of activeTimeRanges and recentU
 `gam print cros ... [listlimit <Number>]`
 
 Added argument to `gam <Users> signature` and `gam <Users> vacation` to allow specification of file character set so that extended characters can be read.
+Credit to Steve Main suggesting the following enhancement.
 Added argument to `gam <Users> signature` and `gam <Users> vacation` to allow pattern substitution in the signature and vacation message.
-`gam <Users> signature <String>|(file <FileName> [charset <Charset>]) (replace <REPattern> <String>)*`
+`gam <Users> signature <String>|(file <FileName> [charset <Charset>]) (replace <Tag> <String>)*`
-`gam <Users> vacation <TrueValues> subject <String> (message <String>)|(file <FileName> [charset <CharSet>]) (replace <REPattern> <String>)*
+`gam <Users> vacation <TrueValues> subject <String> (message <String>)|(file <FileName> [charset <CharSet>]) (replace <Tag> <String>)*
 	[contactsonly] [domainonly] [startdate <Date>] [enddate <Date>]`
+Every instance of `{<Tag>}` in the signature/message will be replaced by `<String>`. Instances of the form `{RT}...{Text}...{/RT}` will be eliminated
+if there was no `<Tag>` specified that matches `Text` or if a `<Tag>` matching `Text` was specified but the matching `<String>` is empty.
 This is especially useful with CSV files.
 `gam csv Users.csv gam user "~User" signature file SignatureTemplate.txt replace "#User#" "~User" replace "#Title#" "~Title"`