From da4291544fe92b18da8f90a757dd412605b7b54b Mon Sep 17 00:00:00 2001
From: M K <mkpro118@gmail.com>
Date: Mon, 1 Jul 2024 16:41:36 -0500
Subject: [PATCH] Implemented NFA State functions

---
 src/nfa_state.c | 100 ++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 100 insertions(+)
 create mode 100644 src/nfa_state.c

diff --git a/src/nfa_state.c b/src/nfa_state.c
new file mode 100644
index 0000000..3946949
--- /dev/null
+++ b/src/nfa_state.c
@@ -0,0 +1,100 @@
+#include "nfa_state.h"
+#include "list.h"
+
+/**
+ * Collection of transition states
+ *
+ * Members
+ *    - capacity: Cacpacity of this collection, i.e, max elements it can hold
+ *    - size: Size of this collection, i.e, number of elements it currently has
+ *    - list: The underlying list of transition states
+ */
+CREATE_LIST_FOR(NFAState, NFAStateList)
+
+// Create and initialize a heap allocated NFA State
+NFAState* state_create(bool is_final) {
+    NFAState* state = malloc(sizeof(NFAState));
+    if (state == NULL) {
+        return NULL;
+    }
+
+    if (state_init(state, is_final) != 0) {
+        free(state);
+        return NULL;
+    }
+
+    return state;
+}
+
+// Initialize the given NFA State
+int state_init(NFAState* state, bool is_final) {
+    if (state == NULL) {
+        return -1;
+    }
+
+    state->is_final = is_final;
+
+    for (int i = 0; i < MAX_N_TRANSITIONS; i++) {
+        state->transitions[i] = NULL;
+    }
+
+    return 0;
+}
+
+// Release the memory used by this NFA State.
+void state_free(NFAState* state) {
+    if (state == NULL) {
+        return;
+    }
+
+    for (int i = 0; i < MAX_N_TRANSITIONS; i++) {
+        if (state->transitions[i] != NULL) {
+            NFAStateList_free(state->transitions[i], state_free);
+            free(state->transitions[i]);
+        }
+        state->transitions[i] = NULL;
+    }
+}
+
+static inline int char_hash(char c) {
+    return c == 0 ? c : (int) (c - 0x1F);
+}
+
+// Add a link between the `from` and `to` state for the `on` character.
+int add_transition(NFAState* from, NFAState* to, char on) {
+    if (from == NULL || to == NULL) {
+        return -1;
+    }
+
+    // Calculate the index for the transition
+    int index = char_hash(on);
+    if (index < 0 || index >= MAX_N_TRANSITIONS) {
+        return -1;  // Invalid character
+    }
+
+    // If the transition list doesn't exist, create it
+    if (from->transitions[index] == NULL) {
+        from->transitions[index] = NFAStateList_create(1);
+        if (from->transitions[index] == NULL) {
+            return -1;
+        }
+    }
+
+    // Add the transition
+    int size = NFAStateList_add(from->transitions[index], to);
+    return size;
+}
+
+// Get the transition for the `on` character for the given NFA State
+NFAStateList* get_transition(NFAState* from, char on) {
+    if (from == NULL) {
+        return NULL;
+    }
+
+    int index = char_hash(on);
+    if (index < 0 || index >= MAX_N_TRANSITIONS) {
+        return NULL;  // Invalid character
+    }
+
+    return from->transitions[index];
+}