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In computer science, an operator-precedence parser is a bottom-up parser that interprets an operator-precedence grammar. For example, most calculators use operator-precedence parsers to convert from the human-readable infix notation relying on order of operations to a format that is optimized for evaluation such as Reverse Polish notation (RPN).
In computer science, a compiler-compiler or compiler generator is a programming tool that creates a parser, interpreter, or compiler from some form of formal description of a programming language and machine. The most common type of compiler-compiler is called a parser generator. [1] It handles only syntactic analysis.
For compilers, the parsing itself can be done in one pass or multiple passes – see one-pass compiler and multi-pass compiler. The implied disadvantages of a one-pass compiler can largely be overcome by adding fix-ups , where provision is made for code relocation during the forward pass, and the fix-ups are applied backwards when the current ...
A predictive parser is a recursive descent parser that does not require backtracking. [3] Predictive parsing is possible only for the class of LL( k ) grammars, which are the context-free grammars for which there exists some positive integer k that allows a recursive descent parser to decide which production to use by examining only the next k ...
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.
An LR parser scans and parses the input text in one forward pass over the text. The parser builds up the parse tree incrementally, bottom up, and left to right, without guessing or backtracking. At every point in this pass, the parser has accumulated a list of subtrees or phrases of the input text that have been already parsed.
An operator precedence parser usually does not store the precedence table with the relations, which can get rather large. Instead, precedence functions f and g are defined. [ 7 ] They map terminal symbols to integers, and so the precedence relations between the symbols are implemented by numerical comparison: f ( a ) < g ( b ...
A shift-reduce parser is a class of efficient, table-driven bottom-up parsing methods for computer languages and other notations formally defined by a grammar. The parsing methods most commonly used for parsing programming languages , LR parsing and its variations, are shift-reduce methods. [ 1 ]