From 2e893fd0df7dae8c4ae843d4a23acb098dd97aff Mon Sep 17 00:00:00 2001
From: filip <“filip.rabiega@gmail.com”>
Date: Tue, 22 Apr 2025 18:38:38 +0200
Subject: added a functional parser

---
 lib/lexing/utils.ml | 36 ++++++++++++++++++++++++++++++++++++
 1 file changed, 36 insertions(+)
 create mode 100644 lib/lexing/utils.ml

(limited to 'lib/lexing/utils.ml')

diff --git a/lib/lexing/utils.ml b/lib/lexing/utils.ml
new file mode 100644
index 0000000..aa218f5
--- /dev/null
+++ b/lib/lexing/utils.ml
@@ -0,0 +1,36 @@
+open Types
+open Headers
+
+(* Function for stepping through a TDFA computation *)
+let step (automaton : tdfa) (state : tdfa_state) : tdfa_state =
+  match state.to_parse with
+  | [] -> state
+  | c :: cs ->
+    try
+      let next_state_id, f = automaton.delta (state.state_id, c) in
+      let next_tok = f state.register in
+      {
+        state_id = next_state_id;
+        register = next_tok;
+        tokens = state.tokens;
+        to_parse = cs
+      }
+    with (No_Transition (_, c)) ->
+      let token_to_add = state.register in
+      let next_state_id, f = automaton.delta (0, c) in
+      let next_tok = f SKIP in
+      {
+        state_id = next_state_id;
+        register = next_tok;
+        tokens = if token_to_add <> SKIP then token_to_add :: state.tokens else state.tokens;
+        to_parse = cs
+      }
+
+(* Driver to perform a TDFA computation *)
+let rec driver (automaton : tdfa) (state: tdfa_state) : tok list =
+  if
+    state.to_parse = []
+  then
+    List.rev (state.register :: state.tokens) (* ensure that final tag is emitted *)
+  else
+    driver automaton (step automaton state)
-- 
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