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Formal method of specifying context-free grammars originally proposed by John Backus, and slightly improved by Peter Naur in his 1960-01-02 committee document contributing to what became the Algol 60 report. See section Languages and Context-Free Grammars.
Grammars specified as rules that can be applied regardless of context. Thus, if there is a rule which says that an integer can be used as an expression, integers are allowed anywhere an expression is permitted. See section Languages and Context-Free Grammars.
Allocation of memory that occurs during execution, rather than at compile time or on entry to a function.
Analogous to the empty set in set theory, the empty string is a character string of length zero.
A "machine" that has discrete states in which it is said to exist at each instant in time. As input to the machine is processed, the machine moves from state to state as specified by the logic of the machine. In the case of the parser, the input is the language being parsed, and the states correspond to various stages in the grammar rules. See section The Bison Parser Algorithm.
A parsing algorithm that can handle all context-free grammars, including those that are not LALR(1). It resolves situations that Bison's usual LALR(1) algorithm cannot by effectively splitting off multiple parsers, trying all possible parsers, and discarding those that fail in the light of additional right context. See section Generalized LR Parsing.
A language construct that is (in general) grammatically divisible; for example, `expression' or `declaration' in C. See section Languages and Context-Free Grammars.
An arithmetic operator that is placed between the operands on which it performs some operation.
A continuous flow of data between devices or programs.
One of the typical usage schemas of the language. For example, one of
the constructs of the C language is the
See section Languages and Context-Free Grammars.
Operators having left associativity are analyzed from left to right: `a+b+c' first computes `a+b' and then combines with `c'. See section Operator Precedence.
A rule whose result symbol is also its first component symbol; for example, `expseq1 : expseq1 ',' exp;'. See section Recursive Rules.
Parsing a sentence of a language by analyzing it token by token from left to right. See section The Bison Parser Algorithm.
A function that reads an input stream and returns tokens one by one.
See section The Lexical Analyzer Function
A flag, set by actions in the grammar rules, which alters the way tokens are parsed. See section Lexical Tie-ins.
A token which consists of two or more fixed characters. See section Symbols, Terminal and Nonterminal.
A token already read but not yet shifted. See section Lookahead Tokens.
The class of context-free grammars that Bison (like most other parser generators) can handle; a subset of LR(1). See section Mysterious Reduce/Reduce Conflicts.
The class of context-free grammars in which at most one token of lookahead is needed to disambiguate the parsing of any piece of input.
A grammar symbol standing for a grammatical construct that can be expressed through rules in terms of smaller constructs; in other words, a construct that is not a token. See section Symbols, Terminal and Nonterminal.
A function that recognizes valid sentences of a language by analyzing the syntax structure of a set of tokens passed to it from a lexical analyzer.
An arithmetic operator that is placed after the operands upon which it performs some operation.
Replacing a string of nonterminals and/or terminals with a single nonterminal, according to a grammar rule. See section The Bison Parser Algorithm.
A reentrant subprogram is a subprogram which can be in invoked any number of times in parallel, without interference between the various invocations. See section A Pure (Reentrant) Parser.
A language in which all operators are postfix operators.
A rule whose result symbol is also its last component symbol; for example, `expseq1: exp ',' expseq1;'. See section Recursive Rules.
In computer languages, the semantics are specified by the actions taken for each instance of the language, i.e., the meaning of each statement. See section Defining Language Semantics.
A parser is said to shift when it makes the choice of analyzing further input from the stream rather than reducing immediately some already-recognized rule. See section The Bison Parser Algorithm.
A single character that is recognized and interpreted as is. See section From Formal Rules to Bison Input.
The nonterminal symbol that stands for a complete valid utterance in the language being parsed. The start symbol is usually listed as the first nonterminal symbol in a language specification. See section The Start-Symbol.
A data structure where symbol names and associated data are stored
during parsing to allow for recognition and use of existing
information in repeated uses of a symbol. See section Multi-Function Calculator:
An error encountered during parsing of an input stream due to invalid syntax. See section Error Recovery.
A basic, grammatically indivisible unit of a language. The symbol that describes a token in the grammar is a terminal symbol. The input of the Bison parser is a stream of tokens which comes from the lexical analyzer. See section Symbols, Terminal and Nonterminal.
A grammar symbol that has no rules in the grammar and therefore is grammatically indivisible. The piece of text it represents is a token. See section Languages and Context-Free Grammars.
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