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The most vexing parse is a counterintuitive form of syntactic ambiguity resolution in the C++ programming language. In certain situations, the C++ grammar cannot distinguish between the creation of an object parameter and specification of a function's type. In those situations, the compiler is required to interpret the line as a function type ...
In computer science, an ambiguous grammar is a context-free grammar for which there exists a string that can have more than one leftmost derivation or parse tree. [ 1 ] [ 2 ] Every non-empty context-free language admits an ambiguous grammar by introducing e.g. a duplicate rule.
In the C++ programming language, argument-dependent lookup (ADL), or argument-dependent name lookup, [1] applies to the lookup of an unqualified function name depending on the types of the arguments given to the function call. This behavior is also known as Koenig lookup, as it is often attributed to Andrew Koenig, though he is not its inventor ...
A derivation of a string for a grammar is a sequence of grammar rule applications that transform the start symbol into the string. A derivation proves that the string belongs to the grammar's language. A derivation is fully determined by giving, for each step: the rule applied in that step; the occurrence of its left-hand side to which it is ...
A parsing expression is a kind of pattern that each string may either match or not match.In case of a match, there is a unique prefix of the string (which may be the whole string, the empty string, or something in between) which has been consumed by the parsing expression; this prefix is what one would usually think of as having matched the expression.
The dangling else is a problem in programming of parser generators in which an optional else clause in an if–then(–else) statement can make nested conditional statements ambiguous. Formally, the reference context-free grammar of the language is ambiguous, meaning there is more than one correct parse tree.
Virtual inheritance is a C++ technique that ensures only one copy of a base class ' s member variables are inherited by grandchild derived classes. Without virtual inheritance, if two classes B and C inherit from a class A , and a class D inherits from both B and C , then D will contain two copies of A ' s member variables: one via B , and one ...
Expression templates allow users to approximate the syntax of extended Backus–Naur form (EBNF) completely in C++. Parser objects are composed through operator overloading and the result is a backtracking LL(∞) parser that is capable of parsing rather ambiguous grammars. Spirit can be used for both lexing and parsing, together or separately.