From 0f44e93680431e0fdbbff7ef76952eed89ed848f Mon Sep 17 00:00:00 2001
From: Nathan Bergey <nathan.bergey@gmail.com>
Date: Tue, 13 Sep 2022 21:58:58 -0400
Subject: [PATCH] Bm: Break out lookup table, and remove prints

---
 src/bm.py | 49 ++++++++++++++++---------------------------------
 1 file changed, 16 insertions(+), 33 deletions(-)

diff --git a/src/bm.py b/src/bm.py
index 8dce228..7763a58 100644
--- a/src/bm.py
+++ b/src/bm.py
@@ -2,8 +2,10 @@ from typing import Dict
 
 
 def make_km_table(pattern: str) -> Dict[str, int]:
-    table = dict()
-    raise Exception("TODO")
+    PATTERN_LENGTH = len(pattern)
+    table = {}
+    for index_from_left, char in enumerate(pattern[:-1]):
+        table[char] = PATTERN_LENGTH - index_from_left - 1
     return table
 
 
@@ -11,44 +13,25 @@ class Bm(object):
     def __init__(self, text: str, pattern: str):
         self.text = text
         self.pattern = pattern
-        # self.table = make_km_table(pattern)
+        self.table = make_km_table(pattern)
 
     def decide_slide_width(self, c: str) -> int:
-        assert len(c) == 1
-        raise Exception("TODO")
-        return -1
+        try:
+            return self.table[c]
+        except KeyError:
+            return len(self.pattern)
 
     def search(self) -> int:
         PATTERN_LENGTH = len(self.pattern)
-        TEXT_LENGTH = len(self.text)
-
-        END_OF_PATTERN = PATTERN_LENGTH - 1
-        LAST_CHAR_OF_PATTERN = self.pattern[-1]
-
-        offset = {c: PATTERN_LENGTH - i -1  for i, c in enumerate(self.pattern[:-1])}
-        print(offset)
-
-        matches = []
-        head = END_OF_PATTERN
-
-        while head < TEXT_LENGTH:
-            print(f'{" " * (head - PATTERN_LENGTH + 1)}{self.pattern}')
-            print(self.text[:head + 1])
-            print(f'{" " * head}^')
-
-            if self.text[head] == LAST_CHAR_OF_PATTERN:
-                for i, c in enumerate(reversed(self.pattern)):
-                    # print(text[head - i], c)
-                    if self.text[head - i] != c:
-                        head += offset[self.text[head]]
+        head = PATTERN_LENGTH - 1
+        while head < len(self.text):
+            if self.text[head] == self.pattern[-1]:
+                for index_from_right, char in enumerate(reversed(self.pattern)):
+                    if self.text[head - index_from_right] != char:
+                        head += self.decide_slide_width(self.text[head])
                         break
                 else:
-                    print("!!!")
                     return head - PATTERN_LENGTH + 1
             else:
-                try:
-                    head += offset[self.text[head]]
-                except KeyError:
-                    head += PATTERN_LENGTH
-            print('----------------------------------')
+                head += self.decide_slide_width(self.text[head])
         return -1