Implement regex initialization

2 files changed, 104 insertions, 0 deletions

diff --git a/src/nre.nim b/src/nre.nim
new file mode 100644
index 000000000..79d689bcd
--- /dev/null
+++ b/src/nre.nim
@@ -0,0 +1,97 @@
+import private.pcre as pcre
+import private.util
+import tables
+import unsigned
+from strutils import toLower
+
+# PCRE Options {{{
+
+let Options: Table[string, int] = {
+  "8" : pcre.UTF8,
+  "9" : pcre.NEVER_UTF,
+  "?" : pcre.NO_UTF8_CHECK,
+  "A" : pcre.ANCHORED,
+  # "C" : pcre.AUTO_CALLOUT, unsuported XXX
+  "E" : pcre.DOLLAR_ENDONLY,
+  "f" : pcre.FIRSTLINE,
+  "i" : pcre.CASELESS,
+  "J" : pcre.DUPNAMES,
+  "m" : pcre.MULTILINE,
+  "N" : pcre.NO_AUTO_CAPTURE,
+  "O" : pcre.NO_AUTO_POSSESS,
+  "s" : pcre.DOTALL,
+  "U" : pcre.UNGREEDY,
+  "W" : pcre.UCP,
+  "X" : pcre.EXTRA,
+  "x" : pcre.EXTENDED,
+  "Y" : pcre.NO_START_OPTIMIZE,
+
+  "any"         : pcre.NEWLINE_ANY,
+  "anycrlf"     : pcre.NEWLINE_ANYCRLF,
+  "cr"          : pcre.NEWLINE_CR,
+  "crlf"        : pcre.NEWLINE_CRLF,
+  "lf"          : pcre.NEWLINE_LF,
+  "bsr_anycrlf" : pcre.BSR_ANYCRLF,
+  "bsr_unicode" : pcre.BSR_UNICODE,
+  "js"          : pcre.JAVASCRIPT_COMPAT,
+}.toTable
+
+proc tokenizeOptions(opts: string): tuple[flags: int, study: bool] =
+  result = (0, false)
+
+  var longOpt: string = nil
+  for i, c in opts:
+    # Handle long options {{{
+    if c == '<':
+      longOpt = ""
+      continue
+
+    if longOpt != nil:
+      if c == '>':
+        result.flags = result.flags or Options.fget(longOpt)
+        longOpt = nil
+      else:
+        longOpt.add(c.toLower)
+      continue
+    # }}}
+
+    if c == 'S':  # handle study
+      result.study = true
+      continue
+
+    result.flags = result.flags or Options.fget($c)
+
+# }}}
+
+type
+  Regex* = ref object
+    pcreObj: ptr pcre.Pcre
+    pcreExtra: ptr pcre.ExtraData
+
+  SyntaxError* = ref object of Exception
+    pos*: int  ## the location of the syntax error in bytes
+    pattern*: string  ## the pattern that caused the problem
+
+  StudyError* = ref object of Exception
+
+proc initRegex*(pattern: string, options = "Sx"): Regex =
+  new result
+
+  var errorMsg: cstring
+  var errOffset: cint
+
+  let opts = tokenizeOptions(options)
+
+  result.pcreObj = pcre.compile(cstring(pattern),
+                                # better hope int is at least 4 bytes..
+                                cint(opts.flags), addr errorMsg,
+                                addr errOffset, nil)
+  if result.pcreObj == nil:
+    # failed to compile
+    raise SyntaxError(msg: $errorMsg, pos: errOffset, pattern: pattern)
+
+  if opts.study:
+    # XXX investigate JIT
+    result.pcreExtra = pcre.study(result.pcreObj, 0x0, addr errorMsg)
+    if result.pcreExtra == nil:
+      raise StudyError(msg: $errorMsg)
diff --git a/src/private/util.nim b/src/private/util.nim
new file mode 100644
index 000000000..afd90a485
--- /dev/null
+++ b/src/private/util.nim
@@ -0,0 +1,7 @@
+import tables
+
+proc fget*[K, V](self: Table[K, V], key: K): V =
+  if self.hasKey(key):
+    return self[key]
+  else:
+    raise newException(KeyError, "Key does not exist in table: " & $key)