diff --git a/vlib/example/plex_test.c b/vlib/example/plex_test.c
new file mode 100644
index 0000000..947f25b
--- /dev/null
+++ b/vlib/example/plex_test.c
@@ -0,0 +1,490 @@
+/*
+ * Copyright (c) 2015 Cisco and/or its affiliates.
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at:
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+#include <vlib/parse.h>
+#include <vlib/unix/unix.h>
+
+static u8 * format_value_v4_address (u8 * s, va_list * args)
+{
+  vlib_parse_value_t *v = va_arg (*args, vlib_parse_value_t *);
+  u32 a = v->value.as_uword;
+
+  s = format (s, "%d.%d.%d.%d",
+	      (a>>24) & 0xFF,
+	      (a>>16) & 0xFF,
+	      (a>>8)  & 0xFF,
+	      (a>>0)  & 0xFF);
+
+  return s;
+}
+
+static vlib_parse_match_t
+v4_address_match (vlib_parse_main_t *pm, vlib_parse_type_t *type, 
+		  vlib_lex_token_t *t, vlib_parse_value_t *valuep)
+{
+  u32 digit;
+  u32 value = 0;
+  int i;
+
+  if (vec_len (pm->tokens) - (t - pm->tokens) < 7)
+    return VLIB_PARSE_MATCH_FAIL;
+
+  /* NUMBER DOT NUMBER DOT NUMBER DOT NUMBER */
+
+  for (i = 0; i < 7; i++) {
+    if ((i & 1) == 0) {
+      if (t[i].token != VLIB_LEX_number)
+	return VLIB_PARSE_MATCH_FAIL;
+      if (t[i].value.as_uword > 0xff)
+	return VLIB_PARSE_MATCH_FAIL;
+      digit = t[i].value.as_uword;
+      value = (value << 8) | digit;
+    } else {
+      if (t[i].token != VLIB_LEX_dot)
+	return VLIB_PARSE_MATCH_FAIL;
+    }
+  }
+  /* note: caller advances by 1 */
+  pm->current_token_index += 6;
+  valuep->value.as_uword = value;
+  return VLIB_PARSE_MATCH_VALUE;
+}
+
+PARSE_TYPE_INIT (v4_address, v4_address_match, 0, format_value_v4_address)
+
+static u8 * format_value_v4_address_and_mask (u8 * s, va_list * args)
+{
+  vlib_parse_value_t *v = va_arg (*args, vlib_parse_value_t *);
+  u32 * a = v->value.as_pointer;
+
+  s = format (s, "%d.%d.%d.%d",
+	      (a[0]>>24) & 0xFF,
+	      (a[0]>>16) & 0xFF,
+	      (a[0]>>8)  & 0xFF,
+	      (a[0]>>0)  & 0xFF);
+  s = format (s, "/%d", a[1]);
+
+  return s;
+}
+
+static vlib_parse_match_t
+v4_address_and_mask_match (vlib_parse_main_t *pm, vlib_parse_type_t *type, 
+			   vlib_lex_token_t *t, vlib_parse_value_t *valuep)
+{
+  u32 digit;
+  u32 address = 0;
+  u32 *rv = 0;
+  int i;
+
+  if (vec_len (pm->tokens) - (t - pm->tokens) < 9)
+    return VLIB_PARSE_MATCH_FAIL;
+
+  /* NUMBER DOT NUMBER DOT NUMBER DOT NUMBER */
+
+  for (i = 0; i < 7; i++) {
+    if ((i & 1) == 0) {
+      if (t[i].token != VLIB_LEX_number)
+	return VLIB_PARSE_MATCH_FAIL;
+      if (t[i].value.as_uword > 0xff)
+	return VLIB_PARSE_MATCH_FAIL;
+      digit = t[i].value.as_uword;
+      address = (address << 8) | digit;
+    } else {
+      if (t[i].token != VLIB_LEX_dot)
+	return VLIB_PARSE_MATCH_FAIL;
+    }
+  }
+
+  if (t[7].token != VLIB_LEX_slash || t[8].token != VLIB_LEX_number)
+    return VLIB_PARSE_MATCH_FAIL;
+
+  vec_add1 (rv, address);
+  vec_add1 (rv, t[8].value.as_uword);
+
+  /* note: caller advances by 1 */
+  pm->current_token_index += 8;
+  valuep->value.as_pointer = rv;
+  return VLIB_PARSE_MATCH_VALUE;
+}
+
+void v4_address_and_mask_cleanup (vlib_parse_value_t *valuep)
+{
+  u32 * trash = valuep->value.as_pointer;
+  vec_free (trash);
+}
+
+PARSE_TYPE_INIT (v4_address_and_mask, v4_address_and_mask_match, 
+                 v4_address_and_mask_cleanup, 
+                 format_value_v4_address_and_mask)
+
+vlib_lex_main_t vlib_lex_main;
+
+
+
+vlib_parse_match_t eval_factor0 (vlib_parse_main_t *pm, 
+                                 vlib_parse_item_t *item,
+                                 vlib_parse_value_t *value)
+{
+  clib_warning ("%U", format_vlib_parse_value, pm);
+  return VLIB_PARSE_MATCH_RULE;
+}
+vlib_parse_match_t eval_factor1 (vlib_parse_main_t *pm, 
+                                 vlib_parse_item_t *item,
+                                 vlib_parse_value_t *value)
+{
+  clib_warning ("%U", format_vlib_parse_value, pm);
+  return VLIB_PARSE_MATCH_RULE;
+}
+vlib_parse_match_t eval_factor2 (vlib_parse_main_t *pm, 
+                                 vlib_parse_item_t *item,
+                                 vlib_parse_value_t *value)
+{
+  word a;
+  int index = vec_len (pm->parse_value)-1;
+  
+  a = pm->parse_value [index].value.as_word;
+  
+  pm->parse_value[index].value.as_word = -a;
+  return VLIB_PARSE_MATCH_RULE;
+}
+vlib_parse_match_t eval_term0 (vlib_parse_main_t *pm, 
+                               vlib_parse_item_t *item,
+                               vlib_parse_value_t *value)
+{
+  clib_warning ("%U", format_vlib_parse_value, pm);
+  return VLIB_PARSE_MATCH_RULE;
+}
+vlib_parse_match_t eval_term1 (vlib_parse_main_t *pm, 
+                               vlib_parse_item_t *item,
+                               vlib_parse_value_t *value)
+{
+  uword a, b;
+  int index = vec_len (pm->parse_value)-2;
+  
+  a = pm->parse_value [index].value.as_uword;
+  b = pm->parse_value [index+1].value.as_uword;
+  
+  pm->parse_value[index].value.as_uword = a * b;
+  _vec_len (pm->parse_value) -= 1;
+  clib_warning ("%U", format_vlib_parse_value, pm);
+  
+  return VLIB_PARSE_MATCH_RULE;
+}
+vlib_parse_match_t eval_term2 (vlib_parse_main_t *pm, 
+                               vlib_parse_item_t *item,
+                               vlib_parse_value_t *value)
+{
+  uword a, b;
+  int index = vec_len (pm->parse_value)-2;
+  
+  a = pm->parse_value [index].value.as_uword;
+  b = pm->parse_value [index+1].value.as_uword;
+  
+  pm->parse_value[index].value.as_uword = a / b;
+  _vec_len (pm->parse_value) -= 1;
+  clib_warning ("%U", format_vlib_parse_value, pm);
+  
+  return VLIB_PARSE_MATCH_RULE;
+}
+vlib_parse_match_t eval_exp0 (vlib_parse_main_t *pm, 
+                              vlib_parse_item_t *item,
+                              vlib_parse_value_t *value)
+{
+  return VLIB_PARSE_MATCH_RULE;
+}
+vlib_parse_match_t eval_exp1 (vlib_parse_main_t *pm, 
+                              vlib_parse_item_t *item,
+                              vlib_parse_value_t *value)
+{
+  uword a, b;
+  int index = vec_len (pm->parse_value)-2;
+  
+  a = pm->parse_value [index].value.as_uword;
+  b = pm->parse_value [index+1].value.as_uword;
+  
+  pm->parse_value[index].value.as_uword = a + b;
+  _vec_len (pm->parse_value) -= 1;
+  clib_warning ("%U", format_vlib_parse_value, pm);
+  
+  return VLIB_PARSE_MATCH_RULE;
+}
+vlib_parse_match_t eval_exp2 (vlib_parse_main_t *pm, 
+                              vlib_parse_item_t *item,
+                              vlib_parse_value_t *value)
+{
+  uword a, b;
+  int index = vec_len (pm->parse_value)-2;
+  
+  a = pm->parse_value [index].value.as_uword;
+  b = pm->parse_value [index+1].value.as_uword;
+  
+  pm->parse_value[index].value.as_uword = a - b;
+  _vec_len (pm->parse_value) -= 1;
+  clib_warning ("%U", format_vlib_parse_value, pm);
+  
+  return VLIB_PARSE_MATCH_RULE;
+}
+
+vlib_parse_match_t eval_result (vlib_parse_main_t *pm, 
+                                vlib_parse_item_t *item,
+                                vlib_parse_value_t *value)
+{
+  clib_warning ("%U", format_vlib_parse_value, pm);
+  return VLIB_PARSE_MATCH_DONE;
+}
+
+vlib_parse_match_t noop_match_rule (vlib_parse_main_t *pm, 
+                               vlib_parse_item_t *item,
+                               vlib_parse_value_t *value)
+{
+  clib_warning ("%U", format_vlib_parse_value, pm);
+  return VLIB_PARSE_MATCH_RULE;
+}
+
+#if 0
+PARSE_INIT (t1, "moo", eval0);
+PARSE_INIT (t2, "moo cow mumble", eval1);
+PARSE_INIT (t3, "moo cow", eval2);
+PARSE_INIT (t4, "moo cow mumble grunch", eval3);
+#endif
+
+#if 0
+PARSE_INIT (r1, "eval <exp>", eval_result);
+
+PARSE_INIT (r2, "<exp> = <term><exp2>", eval_exp0);
+PARSE_INIT (r3, "<exp2> = <plus> <exp>", eval_exp1);
+PARSE_INIT (r4, "<exp2> = <minus> <exp>", eval_exp2);
+PARSE_INIT (r5, "<exp2> = ", noop_match_rule);
+PARSE_TYPE_INIT (exp, rule_match, 0, 0);
+PARSE_TYPE_INIT (exp2, rule_match, 0, 0);
+
+PARSE_INIT (r6, "<term> = <factor><term2>", eval_term0);
+PARSE_INIT (r7, "<term2> = <star> <term>", eval_term1);
+PARSE_INIT (r8, "<term2> = <slash> <term>", eval_term2);
+PARSE_INIT (r9, "<term2> = ", noop_match_rule);
+PARSE_TYPE_INIT (term, rule_match, 0, 0);
+PARSE_TYPE_INIT (term2, rule_match, 0, 0);
+
+PARSE_INIT (r11, "<factor> = <lpar> <exp> <rpar>", eval_factor1);
+PARSE_INIT (r10, "<factor> = <number>", eval_factor0);
+PARSE_INIT (r12, "<factor> = <minus> <factor>", eval_factor2);
+
+PARSE_TYPE_INIT (factor, rule_match, 0, 0);
+#endif
+
+PARSE_INIT (r1, "eval <exp>", eval_result);
+
+#if 1
+PARSE_INIT (r2, "<exp> = <term><exp2>", eval_exp0);
+PARSE_INIT (r3, "<exp2> = <plus> <exp>", eval_exp1);
+PARSE_INIT (r4, "<exp2> = <minus> <exp>", eval_exp2);
+PARSE_INIT (r5, "<exp2> = ", noop_match_rule);
+PARSE_TYPE_INIT (exp, rule_match, 0, 0);
+PARSE_TYPE_INIT (exp2, rule_match, 0, 0);
+
+PARSE_INIT (r6, "<term> = <factor><term2>", eval_term0);
+PARSE_INIT (r7, "<term2> = <star> <term>", eval_term1);
+PARSE_INIT (r8, "<term2> = <slash> <term>", eval_term2);
+PARSE_INIT (r9, "<term2> = ", noop_match_rule);
+PARSE_TYPE_INIT (term, rule_match, 0, 0);
+PARSE_TYPE_INIT (term2, rule_match, 0, 0);
+
+PARSE_INIT (r11, "<factor> = <lpar> <exp> <rpar>", eval_factor1);
+PARSE_INIT (r10, "<factor> = <number>", eval_factor0);
+PARSE_INIT (r12, "<factor> = <minus> <factor>", eval_factor2);
+
+PARSE_TYPE_INIT (factor, rule_match, 0, 0);
+#endif
+
+#if 0
+PARSE_TYPE_INIT (exp, rule_match, 0, 0);
+PARSE_INIT (r6, "<exp> = a b", eval_term0);
+PARSE_INIT (r7, "<exp> = c d", eval_term1);
+PARSE_INIT (r9, "<exp> = ", noop_match_rule);
+#endif
+
+#if 0
+#define foreach_rule_evaluator                  \
+_(0)                                            \
+_(1)                                            \
+_(2)						\
+_(3)
+
+#define _(n)                                            \
+vlib_parse_match_t eval##n (vlib_parse_main_t *pm,      \
+                            vlib_parse_item_t *item,    \
+                            vlib_parse_value_t *value)  \
+{                                                       \
+  clib_warning ("%U", format_vlib_parse_value, pm);     \
+  return VLIB_PARSE_MATCH_DONE;                         \
+}
+foreach_rule_evaluator
+
+#undef _
+
+PARSE_INIT (r1, "eval <moo>", eval_result);
+
+PARSE_INIT (r2, "<moo> = cow", eval0);
+PARSE_INIT (r4, "<moo> = ", eval1);
+PARSE_TYPE_INIT (moo, rule_match, 0, 0);
+#endif 
+
+
+clib_error_t *test_init (vlib_main_t *vm)
+{
+  clib_error_t *error;
+
+  if ((error = vlib_call_init_function (vm, parse_init)))
+    return error;
+
+  return 0;
+}
+
+VLIB_INIT_FUNCTION (test_init);
+
+clib_error_t *
+vlib_stdlex_init (vlib_main_t * vm)
+{
+  vlib_lex_main_t * lm = &vlib_lex_main;
+  u16 top_index;
+  u16 slash_index, slash_star_index, slash_slash_index, slash_star_star_index;
+  u16 slash_token;
+  u16 word_index;
+  u16 zero_index, octal_index, decimal_index, hex_index, binary_index;
+    
+  top_index = vlib_lex_add_table ("top");
+
+#define foreach_top_level_single_character_token        \
+  _('(', lpar)                                          \
+  _(')', rpar)                                          \
+  _(';', semi)                                          \
+  _('[', lbrack)                                        \
+  _(']', rbrack)                                        \
+  _('{', lcurly)                                        \
+  _('}', rcurly)                                        \
+  _('+', plus)                                          \
+  _('-', minus)                                         \
+  _('*', star)                                          \
+  _('%', percent)                                       \
+  _('@', atsign)                                        \
+  _(',', comma)                                         \
+  _('.', dot)                                           \
+  _('?', qmark)
+
+#define _(c,t) \
+  vlib_lex_set_action_range(top_index,c,c,VLIB_LEX_RETURN,vlib_lex_add_token(lm, #t), top_index);
+  foreach_top_level_single_character_token;
+#undef _
+
+  /* Numbers */
+  zero_index = vlib_lex_add_table ("zero");
+  octal_index = vlib_lex_add_table ("octal");
+  decimal_index = vlib_lex_add_table ("decimal");
+  hex_index = vlib_lex_add_table ("hex");
+  binary_index = vlib_lex_add_table ("binary");
+
+  /* Support 0x 0b 0t and 0123 [octal] */
+  vlib_lex_set_action_range (top_index, '0', '0', VLIB_LEX_START_NUMBER, 10, zero_index);
+  vlib_lex_set_action_range (top_index, '1', '9', VLIB_LEX_START_NUMBER, 10, decimal_index);
+
+  vlib_lex_set_action_range (zero_index, 0, 0x7F, VLIB_LEX_RETURN_AND_RESCAN, VLIB_LEX_number, top_index);
+
+  vlib_lex_set_action_range (zero_index, 'x', 'x', VLIB_LEX_IGNORE, ~0, hex_index); 
+  vlib_lex_set_action_range (zero_index, 'b', 'b', VLIB_LEX_IGNORE, ~0, binary_index); 
+  vlib_lex_set_action_range (zero_index, 't', 't', VLIB_LEX_IGNORE, ~0, decimal_index); 
+  vlib_lex_set_action_range (zero_index, '0', '7', VLIB_LEX_START_NUMBER, 8, octal_index);
+    
+  /* Octal */
+  vlib_lex_set_action_range (octal_index, 0, 0x7f, VLIB_LEX_RETURN_AND_RESCAN,
+			VLIB_LEX_number, top_index);
+  vlib_lex_set_action_range (octal_index, '0', '7', VLIB_LEX_ADD_TO_NUMBER, 8, 
+			octal_index);
+
+  /* Decimal */
+  vlib_lex_set_action_range (decimal_index, 0, 0x7f, VLIB_LEX_RETURN_AND_RESCAN,
+			VLIB_LEX_number, top_index);
+  vlib_lex_set_action_range (decimal_index, '0', '9', VLIB_LEX_ADD_TO_NUMBER, 10, 
+			decimal_index);
+    
+  /* Hex */
+  vlib_lex_set_action_range (hex_index, 0, 0x7f, VLIB_LEX_RETURN_AND_RESCAN,
+			VLIB_LEX_number, top_index);
+  vlib_lex_set_action_range (hex_index, '0', '9', VLIB_LEX_ADD_TO_NUMBER, 16, 
+			hex_index);
+  vlib_lex_set_action_range (hex_index, 'a', 'f', VLIB_LEX_ADD_TO_NUMBER, 16, 
+			hex_index);
+  vlib_lex_set_action_range (hex_index, 'A', 'F', VLIB_LEX_ADD_TO_NUMBER, 16, 
+			hex_index);
+    
+  /* Binary */
+  vlib_lex_set_action_range (binary_index, 0, 0x7f, VLIB_LEX_RETURN_AND_RESCAN,
+			VLIB_LEX_number, top_index);
+  vlib_lex_set_action_range (binary_index, '0', '1', VLIB_LEX_ADD_TO_NUMBER, 2, 
+			binary_index);
+
+  /* c/c++ comment syntax is the worst... */
+
+  slash_index = vlib_lex_add_table ("slash");
+  slash_star_index = vlib_lex_add_table ("slash_star");
+  slash_star_star_index = vlib_lex_add_table ("slash_star_star");
+  slash_slash_index = vlib_lex_add_table ("slash_slash");
+  slash_token = vlib_lex_add_token (lm, "slash");
+
+  /* Top level: see a slash, ignore, go to slash table */
+  vlib_lex_set_action_range (top_index, '/', '/', VLIB_LEX_IGNORE, ~0, slash_index);
+
+  /* default for slash table: return SLASH, go to top table */
+  vlib_lex_set_action_range (slash_index, 1, 0x7F, VLIB_LEX_RETURN_AND_RESCAN, slash_token, 
+			top_index);
+  /* see slash-slash, go to s-s table */
+  vlib_lex_set_action_range (slash_index, '/', '/', VLIB_LEX_IGNORE, ~0, 
+			slash_slash_index);
+  /* see slash-star, go to s-* table */
+  vlib_lex_set_action_range (slash_index, '*', '*', VLIB_LEX_IGNORE, ~0, 
+			slash_star_index);
+
+  /* EOL in s-s table, ignore, go to top table */
+  vlib_lex_set_action_range (slash_slash_index, '\n', '\n', VLIB_LEX_IGNORE, ~0, 
+			top_index);
+
+  /* slash-star blah blah star */
+  vlib_lex_set_action_range (slash_star_index, '*', '*', VLIB_LEX_IGNORE, ~0,
+			slash_star_star_index);
+
+  /* slash star blah blah star slash */
+  vlib_lex_set_action_range (slash_star_star_index, '/', '/', VLIB_LEX_IGNORE, ~0,
+			top_index);
+
+  /* LT, =, GT */
+  vlib_lex_set_action_range (top_index, '<', '<', VLIB_LEX_RETURN, VLIB_LEX_lt, top_index);
+  vlib_lex_set_action_range (top_index, '=', '=', VLIB_LEX_RETURN, VLIB_LEX_equals,
+			top_index);
+  vlib_lex_set_action_range (top_index, '>', '>', VLIB_LEX_RETURN, VLIB_LEX_gt, top_index);
+
+  /* words, key and otherwise */
+  word_index = vlib_lex_add_table ("word");
+
+  vlib_lex_set_action_range (top_index, 'a', 'z', VLIB_LEX_ADD_TO_TOKEN, ~0, word_index);
+  vlib_lex_set_action_range (top_index, 'A', 'Z', VLIB_LEX_ADD_TO_TOKEN, ~0, word_index);
+
+  vlib_lex_set_action_range (word_index, 0, 0x7f, VLIB_LEX_KEYWORD_CHECK, ~0, top_index);
+
+  vlib_lex_set_action_range (word_index, 'a', 'z', VLIB_LEX_ADD_TO_TOKEN, ~0, word_index);
+  vlib_lex_set_action_range (word_index, 'A', 'Z', VLIB_LEX_ADD_TO_TOKEN, ~0, word_index);
+  vlib_lex_set_action_range (word_index, '_', '_', VLIB_LEX_ADD_TO_TOKEN, ~0, word_index);
+  vlib_lex_set_action_range (word_index, '0', '9', VLIB_LEX_ADD_TO_TOKEN, ~0, word_index);
+    
+  return 0;
+}
+