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The LALR parser and its alternatives, the SLR parser and the Canonical LR parser, have similar methods and parsing tables; their main difference is in the mathematical grammar analysis algorithm used by the parser generation tool. LALR generators accept more grammars than do SLR generators, but fewer grammars than full LR(1).
The LALR(1) parser is less powerful than the LR(1) parser, and more powerful than the SLR(1) parser, though they all use the same production rules. The simplification that the LALR parser introduces consists in merging rules that have identical kernel item sets, because during the LR(0) state-construction process the lookaheads are not known.
At least one parser generator has implemented LR(*) parsing (i.e. LRSTAR). The challenge is to make LR(*) efficient so that it does not impact the performance of the parser. As long as k (the number of look-aheads) is small, LR(*) parsing is efficient. — Preceding unsigned comment added by Paulbmann (talk • contribs) 10:28, May 23, 2019 (UTC)
The goal of this major revision was to make LR parsers better understood by programmers who are users of LR parser generators, and give an intuitive understanding of the generator's work and parser's work without going into the mathematical details and formalisms of a parsing theory textbook.
An LR(1) parser can handle many but not all common grammars. It is usually possible to manually modify a grammar so that it fits the limitations of LR(1) parsing and the generator tool. The grammar for an LR parser must be unambiguous itself, or must be augmented by tie-breaking precedence rules. This means there is only one correct way to ...
With many LR parser generators, resolving conflicts requires the analysis of the parser automaton, which demands some expertise from the user. To aid the user in understanding conflicts more intuitively, Bison can instead automatically generate counterexamples.
LR languages are strictly more powerful: every LL(1) grammar is LR(1). The converse is not true: grammars containing left recursion may be LR(1) but not LL(1). In short, LR(1) parsers are strictly more powerful, but more difficult to write. That's why parser-generators for LR(1) and related classes, are popular.
An extension of full LR, also I think from Spector although I can't find the reference, is LAR parsing. In an LR parser with a shift/reduce conflict the underlying state machine is searched from the conflict point to construct a sequence of terminal symbols from which a regular expression and consequently a finte state machine is constructed.