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+File: bison.info, Node: Glossary, Next: Index, Prev: Table of Symbols, Up: Top
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+Glossary
+********
+
+Backus-Naur Form (BNF)
+ Formal method of specifying context-free grammars. BNF was first
+ used in the `ALGOL-60' report, 1963. *Note Languages and
+ Context-Free Grammars: Language and Grammar.
+
+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. *Note Languages and Context-Free
+ Grammars: Language and Grammar.
+
+Dynamic allocation
+ Allocation of memory that occurs during execution, rather than at
+ compile time or on entry to a function.
+
+Empty string
+ Analogous to the empty set in set theory, the empty string is a
+ character string of length zero.
+
+Finite-state stack machine
+ 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. *Note The Bison Parser Algorithm: Algorithm.
+
+Grouping
+ A language construct that is (in general) grammatically divisible;
+ for example, `expression' or `declaration' in C. *Note Languages
+ and Context-Free Grammars: Language and Grammar.
+
+Infix operator
+ An arithmetic operator that is placed between the operands on
+ which it performs some operation.
+
+Input stream
+ A continuous flow of data between devices or programs.
+
+Language construct
+ One of the typical usage schemas of the language. For example,
+ one of the constructs of the C language is the `if' statement.
+ *Note Languages and Context-Free Grammars: Language and Grammar.
+
+Left associativity
+ Operators having left associativity are analyzed from left to
+ right: `a+b+c' first computes `a+b' and then combines with `c'.
+ *Note Operator Precedence: Precedence.
+
+Left recursion
+ A rule whose result symbol is also its first component symbol; for
+ example, `expseq1 : expseq1 ',' exp;'. *Note Recursive Rules:
+ Recursion.
+
+Left-to-right parsing
+ Parsing a sentence of a language by analyzing it token by token
+ from left to right. *Note The Bison Parser Algorithm: Algorithm.
+
+Lexical analyzer (scanner)
+ A function that reads an input stream and returns tokens one by
+ one. *Note The Lexical Analyzer Function `yylex': Lexical.
+
+Lexical tie-in
+ A flag, set by actions in the grammar rules, which alters the way
+ tokens are parsed. *Note Lexical Tie-ins::.
+
+Literal string token
+ A token which consists of two or more fixed characters. *Note
+ Symbols::.
+
+Look-ahead token
+ A token already read but not yet shifted. *Note Look-Ahead
+ Tokens: Look-Ahead.
+
+LALR(1)
+ The class of context-free grammars that Bison (like most other
+ parser generators) can handle; a subset of LR(1). *Note
+ Mysterious Reduce/Reduce Conflicts: Mystery Conflicts.
+
+LR(1)
+ The class of context-free grammars in which at most one token of
+ look-ahead is needed to disambiguate the parsing of any piece of
+ input.
+
+Nonterminal symbol
+ 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. *Note Symbols::.
+
+Parse error
+ An error encountered during parsing of an input stream due to
+ invalid syntax. *Note Error Recovery::.
+
+Parser
+ 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.
+
+Postfix operator
+ An arithmetic operator that is placed after the operands upon
+ which it performs some operation.
+
+Reduction
+ Replacing a string of nonterminals and/or terminals with a single
+ nonterminal, according to a grammar rule. *Note The Bison Parser
+ Algorithm: Algorithm.
+
+Reentrant
+ A reentrant subprogram is a subprogram which can be in invoked any
+ number of times in parallel, without interference between the
+ various invocations. *Note A Pure (Reentrant) Parser: Pure Decl.
+
+Reverse polish notation
+ A language in which all operators are postfix operators.
+
+Right recursion
+ A rule whose result symbol is also its last component symbol; for
+ example, `expseq1: exp ',' expseq1;'. *Note Recursive Rules:
+ Recursion.
+
+Semantics
+ In computer languages, the semantics are specified by the actions
+ taken for each instance of the language, i.e., the meaning of each
+ statement. *Note Defining Language Semantics: Semantics.
+
+Shift
+ 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. *Note The Bison Parser Algorithm:
+ Algorithm.
+
+Single-character literal
+ A single character that is recognized and interpreted as is.
+ *Note From Formal Rules to Bison Input: Grammar in Bison.
+
+Start symbol
+ 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.
+ *Note The Start-Symbol: Start Decl.
+
+Symbol table
+ 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. *Note Multi-function
+ Calc::.
+
+Token
+ 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. *Note Symbols::.
+
+Terminal symbol
+ A grammar symbol that has no rules in the grammar and therefore is
+ grammatically indivisible. The piece of text it represents is a
+ token. *Note Languages and Context-Free Grammars: Language and
+ Grammar.
+
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