Unit SS, Part B: String Matching, Shift-Or

Preprocessing:

• Let pat= pattern, A=pattern alphabet
• Each entry "a" in A is represented by a |pat| bit string, indicating where "a" occurs in the pattern

Searching:

• Initial state = |pat| 1's
• Match=0 state: (state<<1)OR T[char]

Advantages:

• Easy to implement in hardware
• Only need to store 1 char. of text (no buffering or text storage)
• Can handle regular expressions: sets of chars, don't cares
• Extends to don't cares or errors in text