2 files changed, 32 insertions, 0 deletions
diff --git a/lib/pure/pegs.nim b/lib/pure/pegs.nim
index 201f13111..e5a655b2e 100755
--- a/lib/pure/pegs.nim
+++ b/lib/pure/pegs.nim
@@ -1371,7 +1371,27 @@ proc peg*(pattern: string): TPeg =
   ##   peg"{\ident} \s* '=' \s* {.*}"
   result = parsePeg(pattern, "pattern")
 
+proc escapePeg*(s: string): string = 
+  ## escapes `s` so that it is matched verbatim when used as a peg.
+  result = ""
+  var inQuote = false
+  for c in items(s):  
+    case c
+    of '\0'..'\31', '\'', '"', '\\': 
+      if inQuote: 
+        result.add('\'')
+        inQuote = false
+      result.add("\\x")
+      result.add(toHex(ord(c), 2))
+    else:
+      if not inQuote: 
+        result.add('\'')
+        inQuote = true
+      result.add(c)
+  if inQuote: result.add('\'')
+
 when isMainModule:
+  assert escapePeg("abc''def'") == r"'abc'\x27\x27'def'\x27"
   assert match("(a b c)", peg"'(' @ ')'")
   assert match("W_HI_Le", peg"\y 'while'")
   assert(not match("W_HI_L", peg"\y 'while'"))
diff --git a/lib/pure/re.nim b/lib/pure/re.nim
index b4aa75637..dfa191963 100755
--- a/lib/pure/re.nim
+++ b/lib/pure/re.nim
@@ -273,6 +273,18 @@ proc split*(s: string, sep: TRegEx): seq[string] =
   ## Splits the string `s` into substrings.
   accumulateResult(split(s, sep))
   
+proc escapeRe*(s: string): string = 
+  ## escapes `s` so that it is matched verbatim when used as a regular 
+  ## expression.
+  result = ""
+  for c in items(s):
+    case c
+    of 'a'..'z', 'A'..'Z', '0'..'9', '_':
+      result.add(c)
+    else: 
+      result.add("\\x")
+      result.add(toHex(ord(c), 2))
+  
 const ## common regular expressions
   reIdentifier* = r"\b[a-zA-Z_]+[a-zA-Z_0-9]*\b"  ## describes an identifier
   reNatural* = r"\b\d+\b" ## describes a natural number