Formal Languages Questions Medium
LR(0) and LR(1) are both types of bottom-up parsing techniques used in formal language theory. The main difference between LR(0) and LR(1) parsing lies in the amount of lookahead used during the parsing process.
LR(0) parsing, also known as the LR(0) item set construction, uses zero lookahead symbols to determine the next action to take. It constructs a set of items for each state, where each item consists of a production rule with a dot indicating the current position in the rule. The LR(0) parser uses these item sets to build a parsing table, which is then used to parse the input string. However, since LR(0) parsing does not consider any lookahead symbols, it may lead to conflicts and ambiguity in certain grammars.
On the other hand, LR(1) parsing, also known as the LR(1) item set construction, uses one lookahead symbol to determine the next action to take. In addition to the production rule and the dot position, each LR(1) item also includes a lookahead symbol. This additional information allows the LR(1) parser to resolve conflicts and ambiguities that may arise in LR(0) parsing. By considering the next input symbol, LR(1) parsing can make more informed decisions during the parsing process.
In summary, the main difference between LR(0) and LR(1) parsing is the amount of lookahead used. LR(0) parsing uses zero lookahead symbols, while LR(1) parsing uses one lookahead symbol. This additional lookahead in LR(1) parsing helps to resolve conflicts and ambiguities that may occur in LR(0) parsing.