From e43394140577187ebd5818c975ba3ebfaff52b8d Mon Sep 17 00:00:00 2001
From: Christian Risi <75698846+CnF-Gris@users.noreply.github.com>
Date: Sun, 28 Sep 2025 18:04:44 +0200
Subject: [PATCH] Added BPE

TODO:
- complete the fit method
---
 .../Libs/BPE/Classes/NanoSocratesBPE.py       | 106 ++++++++++++++++++
 Project_Model/Libs/BPE/Enums/TokenType.py     |   6 +
 Project_Model/Tests/bpe_test.py               |  52 +++++++++
 3 files changed, 164 insertions(+)
 create mode 100644 Project_Model/Libs/BPE/Classes/NanoSocratesBPE.py
 create mode 100644 Project_Model/Libs/BPE/Enums/TokenType.py
 create mode 100644 Project_Model/Tests/bpe_test.py

diff --git a/Project_Model/Libs/BPE/Classes/NanoSocratesBPE.py b/Project_Model/Libs/BPE/Classes/NanoSocratesBPE.py
new file mode 100644
index 0000000..844e860
--- /dev/null
+++ b/Project_Model/Libs/BPE/Classes/NanoSocratesBPE.py
@@ -0,0 +1,106 @@
+from .Encoder import Encoder
+from ..Errors import OutOfDictionaryException
+
+
+class NanoSocratesBatchMemoryBPE:
+
+    def __init__(self) -> None:
+        pass
+
+
+class NanoSocratesBPE(Encoder):
+
+    def __init__(self, vocabulary: dict[tuple[int, int], int] | None = None) -> None:
+        super().__init__()
+
+        self.__vocabulary: dict[tuple[int, int], int] = {}
+        self.__reverse_vocabulary: dict[int, tuple[int, int]] = {}
+
+        if vocabulary is None:
+            return
+
+        for key, value in vocabulary.items():
+            if value < 256:
+                raise OutOfDictionaryException()
+            self.__vocabulary[key] = value
+            self.__reverse_vocabulary[value] = key
+
+    # TODO: implement fit
+    def fit():
+        pass
+
+    def encode(self, piece: str) -> list[int]:
+
+        current_piece = list(map(ord, piece))
+        new_piece = self.__round_encode(current_piece)
+
+        while len(current_piece) != len(new_piece):
+            current_piece = new_piece
+            new_piece = self.__round_encode(current_piece)
+
+        return current_piece
+
+    def __round_encode(self, piece: list[int]):
+
+        if len(piece) == 1:
+            return piece
+
+        PIECE_LENGTH = len(piece) - 1
+        NEW_PIECE = []
+
+        index = 0
+        while index < PIECE_LENGTH:
+
+            CANDIDATE_WORD = (piece[index], piece[index + 1])
+            CANDIDATE_TOKEN = self.__vocabulary.get(CANDIDATE_WORD)
+
+            if CANDIDATE_TOKEN is None:
+                NEW_PIECE.append(piece[index])
+                index += 1
+
+                if index == PIECE_LENGTH:
+                    NEW_PIECE.append(piece[index])
+
+                continue
+
+            NEW_PIECE.append(CANDIDATE_TOKEN)
+            index += 2
+
+
+        return NEW_PIECE
+
+    # TODO: decode
+    def decode(self, token_id: int) -> str:
+
+        token_stack: list[int] = [token_id]
+        DECODED_STRING_ARR: list[str] = []
+
+        while len(token_stack) > 0:
+            TOKEN_ID = token_stack.pop()
+
+            if TOKEN_ID < 256:
+                DECODED_CHAR = chr(TOKEN_ID)
+                DECODED_STRING_ARR.append(
+                    DECODED_CHAR
+                )
+                continue
+
+            left_token, right_token = self.__token_decode(TOKEN_ID)
+
+            token_stack.append(
+                right_token
+            )
+            token_stack.append(
+                left_token
+            )
+
+        return "".join(DECODED_STRING_ARR)
+
+    def __token_decode(self, token_id: int) -> tuple[int, int]:
+
+        CANDIDATE_DECODED = self.__reverse_vocabulary.get(token_id)
+
+        if CANDIDATE_DECODED is None:
+            raise OutOfDictionaryException()
+
+        return CANDIDATE_DECODED
diff --git a/Project_Model/Libs/BPE/Enums/TokenType.py b/Project_Model/Libs/BPE/Enums/TokenType.py
new file mode 100644
index 0000000..7a27c34
--- /dev/null
+++ b/Project_Model/Libs/BPE/Enums/TokenType.py
@@ -0,0 +1,6 @@
+from enum import Enum, auto
+
+class TokenType(Enum):
+
+    SPECIAL = auto()
+    BPE = auto()
\ No newline at end of file
diff --git a/Project_Model/Tests/bpe_test.py b/Project_Model/Tests/bpe_test.py
new file mode 100644
index 0000000..7332f65
--- /dev/null
+++ b/Project_Model/Tests/bpe_test.py
@@ -0,0 +1,52 @@
+from Project_Model.Libs.BPE.Enums import TokenType
+import Project_Model.Libs.BPE as BPE
+
+import re
+
+
+class TestBPE:
+
+    def test_bpe_encoding_simple(self):
+
+        TEXT = "abababab"
+
+        # ab = 256
+        # 256, 256 = 257
+        # 257, 257 = 258
+
+        VOCABULARY = {(ord("a"), ord("b")): 256, (256, 256): 257, (257, 257): 258}
+        EXPECTED = [258]
+
+        BPE_ENCODER = BPE.NanoSocratesBPE(VOCABULARY)
+
+        ENCODED = BPE_ENCODER.encode(TEXT)
+
+        assert len(ENCODED) == len(EXPECTED)
+
+        for encoded, expected in zip(ENCODED, EXPECTED):
+            assert encoded == expected
+
+    def test_bpe_decoding_simple(self):
+
+
+        INPUT = 258
+
+        # ab = 256
+        # 256, 256 = 257
+        # 257, 257 = 258
+
+        VOCABULARY = {(ord("a"), ord("b")): 256, (256, 256): 257, (257, 257): 258}
+        EXPECTED = "abababab"
+
+        BPE_ENCODER = BPE.NanoSocratesBPE(VOCABULARY)
+
+        DECODED = BPE_ENCODER.decode(INPUT)
+
+        assert len(DECODED) == len(EXPECTED)
+
+        for encoded, expected in zip(DECODED, EXPECTED):
+            assert encoded == expected
+
+# Useful to debug weird cases
+if __name__ == "__main__":
+    TestBPE().test_bpe_decoding_simple()