added a functional parser

1 files changed, 23 insertions, 0 deletions

diff --git a/lib/lexing/headers.ml b/lib/lexing/headers.ml
new file mode 100644
index 0000000..2452eec
--- /dev/null
+++ b/lib/lexing/headers.ml
@@ -0,0 +1,23 @@
+(* Types for lexing *)
+
+open Types
+
+(* Exceptions to aid control flow for lexer *)
+exception Not_In_Alphabet of char
+exception No_Transition of int * char
+
+(* Tagged Deterministice Finite Automaton *)
+type tdfa = {
+  alphabet : char list;
+  start_state: int;
+  register_init : tok; (* initial contents of the single register for this TDFA *)
+  delta : int * char -> int * (tok -> tok)
+}
+
+(* Description of a possible state that the TDFA could be in *)
+type tdfa_state = {
+  state_id : int;         (* current state *)
+  register : tok;         (* contents of register *)
+  tokens : tok list;      (* tokens emitted so far *)
+  to_parse : char list;   (* characters left to parse *)
+}