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A bottom-up parse discovers and processes that tree starting from the bottom left end, and incrementally works its way upwards and rightwards. [2] A parser may act on the structure hierarchy's low, mid, and highest levels without ever creating an actual data tree; the tree is then merely implicit in the parser's actions. Bottom-up parsing ...
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).
A canonical LR parser (also called a LR(1) parser) is a type of bottom-up parsing algorithm used in computer science to analyze and process programming languages.It is based on the LR parsing technique, which stands for "left-to-right, rightmost derivation in reverse."
In computer science, a Simple LR or SLR parser is a type of LR parser with small parse tables and a relatively simple parser generator algorithm. As with other types of LR(1) parser, an SLR parser is quite efficient at finding the single correct bottom-up parse in a single left-to-right scan over the input stream, without guesswork or backtracking.
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 ]
Another method [8] is to build the parse forest as you go, augmenting each Earley item with a pointer to a shared packed parse forest (SPPF) node labelled with a triple (s, i, j) where s is a symbol or an LR(0) item (production rule with dot), and i and j give the section of the input string derived by this node. A node's contents are either a ...
An LR(1) parser will create two different states (with non-conflicting lookaheads), neither of which is ambiguous. In an LALR parser this one state has conflicting actions (given lookahead c or d, reduce to E or F), a "reduce/reduce conflict"; the above grammar will be declared ambiguous by a LALR parser generator and conflicts will be reported.
File information Description Bottom-up parse tree for "A*2 + 1" with shift-reduce steps numbered. Used in LR Parser. Source Drawn by me on Google Docs Date 2012-05-12 Author DBSand. Permission (Reusing this file) See below.