Add escapeRe

README.asciidoc

@@ -78,6 +78,12 @@ If `sub` is a string, then each match is replaced with that string, where the
 captures are accessable as `$1`, `$2`, and so on. A literal `$` can be added by
 doubling up like so: `$$`.
 
+[[proc-escapere]]
+==== escapeRe(string): string
+
+Escapes the string so it doesn't match any special characters. Incompatible
+with the Extra flag (`X`).
+
 === RegexMatch
 
 Represents the result of an execution. On failure, it is `nil`. The available

src/nre.nim

@@ -291,6 +291,7 @@ proc initRegex(pattern: string, options: string): Regex =
 proc re*(pattern: string, options = ""): Regex = initRegex(pattern, options)
 # }}}
 
+# Operations {{{
 proc matchImpl(str: string, pattern: Regex, start, endpos: int, flags: int): RegexMatch =
   new(result)
   result.pattern = pattern
@@ -442,3 +443,9 @@ proc replace*(str: string, pattern: Regex,
 proc replace*(str: string, pattern: Regex, sub: string): string =
   return str.replace(pattern, proc (match: RegexMatch): string =
     sub % match.captures.toSeq )
+
+# }}}
+
+let SpecialCharMatcher = re"([\\+*?[^\]$(){}=!<>|:-])"
+proc escapeRe*(str: string): string =
+  str.replace(SpecialCharMatcher, "\\$1")

test/escape.nim

@@ -0,0 +1,7 @@
+import nre, unittest
+
+suite "escape strings":
+  test "escape strings":
+    check("123".escapeRe() == "123")
+    check("[]".escapeRe() == r"\[\]")
+    check("()".escapeRe() == r"\(\)")

test/testall.nim

@@ -5,3 +5,4 @@ import find
 import split
 import match
 import replace
+import escape